Getting Started: An Inductor Design Example

PExprt®

Getting Started: An Inductor Design Example

September 2004

NoticeThe information contained in this document is subject to change without notice.Ansoft makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. Ansoft shall not be liable for errors contained herein or for incidental or consequential damages in connection with the fur-nishing, performance, or use of this material.This document contains proprietary information which is protected by copyright. All rights are reserved.

Ansoft Corporation225 West Station Square Drive Suite 200 Pittsburgh, PA 15219 (412) 261 - 3200

PExprt, PEmag, Maxwell, Maxwell SPICE, SIMPLORER, Equivalent Circuit Extractor, and RMx-prt are registered trademarks or trademarks of Ansoft Corporation. All other trademarks are the property of their respective owners.© 2004 Ansoft Corporation. All rights reserved.

New editions of this manual include material updated since the previous edition. The manual print-ing date, indicating the manual’s current edition, changes when a new edition is printed. Minor cor-rections and updates incorporated at reprint do not cause the date to change.Update packages may be issued between editions and contain additional and/or replacement pages to be merged into the manual by the user. Pages which are rearranged because of changes on a pre-vious page are not considered to be revised.

Edition Date Software Revision

1 September 2002 5.0

2 September 2004 6.0


Conventions Used in this Guide

Getting HelpFor more information on PExprt commands and features, refer to the PExprt online help. To start PExprt, you must first access the Maxwell Control Panel. For more detailed information on the Maxwell Control Panel commands, refer to the Maxwell Control Panel’s online help system.To contact Ansoft technical support staff in your geographical area, please log on to the Ansoft cor-porate website, http://www.ansoft.com, click the Contact button, and then click Support. You will find phone numbers and e-mail addresses for the technical support staff. Your Ansoft account man-ager may also be contacted in order to obtain this information.All Ansoft software files are ASCII text and can be sent conveniently by e-mail. When reporting difficulties, it is extremely helpful to include specific information about what steps were taken or what stages the simulation reached. This allows more rapid and effective debugging.

Field Names Bold type is used for on-screen prompts, field names, and messages.

Keyboard Entries Bold type is used for entries that must be entered as specified. Example: Type 0.005 in the Nonlinear Residual field.

Menu Commands Bold type is used to display menu commands selected to perform a specific task. Menu levels are separated by the “>” symbol.For example, the instruction “Click File>Open” means to select the Open command on the File menu.

Variable Names Italic type is used for keyboard entries when a name or variable must be typed in place of the words in italics. For example, the instruction “copy filename” means to type the word copy, to type a space, and then to type the name of a file, such as file1.

Emphasis and Titles

Italic type is used for emphasis and for the titles of manuals and other publications.

Keyboard Keys Bold type, in a different font, is used for labeled keys on the computer keyboard. For example, the instruction “Press Return” means to press the key on the computer that is labeled Return.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1General Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3Sample Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4Results to Expect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

2. Creating a PExprt Project . . . . . . . . . . . . . . . . . . . . . . . 2-1Access the Maxwell Control Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2Start the Project Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3Create a Project Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4Create a Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Enter Project Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-63. Accessing the Software . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Open the New Project and Run PExprt . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2PExprt Working Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Input/Output Data Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4Elements Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Libraries Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

Preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6Specify Program Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7Specify Modeling Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8Specify Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-8

Units of Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10

Contents-1


4. PExprt Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1Types of Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

Working with Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3Opening Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3Creating New Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Saving Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Closing Stock Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4Saving the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Closing the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Modifying Elements in the Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5

Library Element Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5Creating New Library Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9Copying Elements in the Libraries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

5. Selecting the Design Library . . . . . . . . . . . . . . . . . . . . 5-1Design Library Role . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

Selecting the Design Library . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2Selecting Elements in the Design Library . . . . . . . . . . . . . . . . . . . . . . . . 5-3Auto-Select Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5

6. Converter Input Data . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1Waveforms Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4

7. Design Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1Design Inputs Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

Design Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

8. Modeling Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1Modeling Options Tab of Input/Output Data Area . . . . . . . . . . . . . . . . . . 8-2

Modeling Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6

9. List of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1Starting the Design Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2Using the List of Results Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4Graphical Information Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-6

Contents-2


10. Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . 10-1Selecting a Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-2Exploring the Performance Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10-4

11. Constructive Results . . . . . . . . . . . . . . . . . . . . . . . . . 11-1Exploring the Constructive Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11-2

12. Generating Models . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-1Defining the Modeling Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-3Generating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4

Generate the Analytical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-4View the Model Netlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-5Generate the FEA-based Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-6View the Model Netlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-9

Recalculating Winding Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-10Using the Models to Recalculate Winding Loss . . . . . . . . . . . . . . . . . . 12-10Using the FEA Solver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-11

13. Linking with Maxwell . . . . . . . . . . . . . . . . . . . . . . . . . . 13-1Linking with Maxwell Eddy Current Solver . . . . . . . . . . . . . . . . . . . . . . 13-2Linking with Maxwell Electrostatic Solver . . . . . . . . . . . . . . . . . . . . . . . 13-4Linking with Maxwell Transient Solver . . . . . . . . . . . . . . . . . . . . . . . . . 13-6Linking with Maxwell Thermal Solver . . . . . . . . . . . . . . . . . . . . . . . . . . 13-8

14. Analysis Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-1Selecting Analysis Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14-2

15. Using PExprt with the Modeling Module . . . . . . . . . . 15-1Invoking the Modeling Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-2Generating a Model with the Modeling Module . . . . . . . . . . . . . . . . . . . 15-3Using Models from the Modeling Module in PExprt . . . . . . . . . . . . . . . 15-5Summary of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15-8

16. Linking with SIMPLORER . . . . . . . . . . . . . . . . . . . . . . 16-1Defining the SIMPLORER Model Language . . . . . . . . . . . . . . . . . . . . . 16-2Generating the Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16-3Using a PExprt Model in SIMPLORER . . . . . . . . . . . . . . . . . . . . . . . . . 16-4

17. Planar Magnetic Component Designs . . . . . . . . . . . . 17-1Setting Up the Planar Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-2

Contents-3


18. Toroidal Component Designs . . . . . . . . . . . . . . . . . . 18-1Setting Up the Toroidal Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18-2

Contents-4

1Introduction

Power Electronics Expert (PExprt®) is an interactive, PC-based design tool that uses analytical expressions to design magnetic components such as transformers and inductors. For example, you can use PExprt to design both complex planar components and multi-winding flyback transformers.PExprt produces an optimal magnetic component design based on the waveform or electrical parameters you enter for the power converter and based on the cores, wires, and materials you select from a database. You only need to enter the numerical values, and PExprt automatically com-putes design alternatives.Rather than resulting in a single design alternative, PExprt’s output consists of a complete series of valid designs meeting your specified design objectives. These results can then be evaluated in terms of several criteria, including power loss and temperature rise.PExprt also includes the Modeling module (PEmag), a powerful magnetic analysis module based on finite element analysis (FEA). This module conducts a detailed analysis of geometry, frequency, and material effects not considered by PExprt. The Modeling module also generates behavioral models for use in electrical simulators such as SIMPLORER®, PSPICE®, or Saber®. Using PExprt, you can:• Design inductors, multi-winding transformers, coupled inductors, and flyback type compo-

nents.• Introduce waveform or converter data.• Consider boost, buck, boost-buck, forward, push-pull, half-bridge, full-bridge, and flyback

converters.• Optimize constructive parameters, such as core size, core material, number of turns, air gap

length, wire gage, and number of parallel turns.• Calculate performance parameters, such as winding losses, core losses, flux density, DC and

AC resistance, Irms currents, magnetizing inductance, leakage inductance, and temperature rise.

Introduction 1-1


• Consider complex effects, such as skin and proximity effects, fringing flux near the air-gap for energy calculations, and incremental permeability as a function of the field strength.

• Generate model netlists for Maxwell SPICE®, PSpice®, SIMPLORER®, and Saber® electrical simulators.

• Analyze the entire power electronics application of the resulting model, using an additional electrical simulator (PSpice®, SIMPLORER®, or Saber®).

In this guide, you will use PExprt to model an inductor for a buck converter. This example intro-duces you to the basic functions of PExprt.

The goals for this chapter are to:• Understand the general procedure for creating an inductor design in PExprt.• Review the sample problem and the procedure you will use to generate the design and obtain

results.

1-2 Introduction


General ProcedureTo design a magnetic component in PExprt, follow this general procedure:1. Select a design library from the list of stock libraries.2. Optionally, select cores, wires, and core materials from the design library. Only the selected

elements are considered in the design process.3. Introduce the converter specifications.4. Optionally, specify design inputs, such as gap position, geometry, thermal constraints, wire

spacing, maximum flux density, and maximum number of parallel turns.5. Optionally, select modeling inputs, such as winding losses and optimization criteria.6. Generate a list of possible designs that meet your specifications.7. Select a design, and explore one or more performance results, such as core losses, winding

losses, or temperature rise.8. Select a design, and explore one or more constructive results, such as core size, core material,

wire gauge, gap length, or number of turns.9. Use the Modeler menu to do the following:

• Obtain a SIMPLORER, PSpice, Maxwell SPICE, or Saber subcircuit model of your selected design.

• Link with the Modeling module to:• Optimize the design by generating a new model using another winding strategy.• Compare different winding strategies in order to reduce parasitics (leakage induc-

tance, AC resistance, and capacitances).• Quantify the effect of manufacturing tolerances or material tolerances.• Perform sensitivity analyses.• Analyze the impact of your design within the behavior of the entire circuit (voltage

spikes, efficiency, and ringing).10. Optionally, you can link with SIMPLORER to simulate the entire circuit.

Introduction 1-3


Sample ProblemIn this guide, you will design, model, and simulate an inductor for a buck converter, using both wires and planar conductors.You will use the following specifications in your design:• Input Voltage: 42 V• Output Voltage: 12 V• Switching Frequency: 200 kHz• Output Power: 300 W• Current Ripple: 4.3 A (17 %)

This getting started guide takes you through the setup, design, and modeling of this magnetic com-ponent. You will cover the following steps:1. Designing a low losses inductor from the converter specifications.2. Modeling the inductor using both an analytical-based and a FEA-based model, in order to ana-

lyze the impact of the fringing flux on the power losses.3. Simulating the entire converter, including the FEA-based model, with SIMPLORER.4. Designing a planar version of the inductor.5. Designing a toroidal version of the inductor.

After setting up the problem and generating the solutions, you will do the following:• Select and optimize constructive parameters, including:

• Core size, Core material, Number of turns, Air gap length, Wire gauge, Number of parallel turns.

• Calculate performance parameters, including:• Winding losses, Core losses, Flux density, DC and AC resistance, Irms currents, Magne-

tizing inductance, Leakage inductance, Temperature rise.• Consider complex effects, including:

• Skin and proximity effects, Fringing flux nearby the air-gap for energy calculations, Incre-mental permeability as a function of the field strength, Generate model netlists for the SIMPLORER electrical simulator.

• Analyze the entire power electronics application of the resulting model, using SIMPLORER.

1-4 Introduction


Results to ExpectThe following figures show the type of results you can obtain using PExprt:

Input Data Constructive Results

Performance Results List of Results

Introduction 1-5


Time The total time needed to complete this getting started guide is approximately 3 hours.

BH Magnetic Material Curve Core data

AC Resistance FFT of the current

1-6 Introduction

2Creating a PExprt Project

This guide assumes that the following products have already been installed as described in the Ansoft installation guide:• PExprt, including the Modeling module.• SIMPLORER.Please see the Ansoft PC Installation Guide if you need to install or set up the software.The goals for this chapter are to:• Create a project directory in which to save the sample problems.• Create a new project in that directory in which to save the buck inductor problem.

Time This chapter should take approximately 15 minutes to work through.

Creating a PExprt Project 2-1


Access the Maxwell Control PanelTo access PExprt, you must first access the Maxwell Control Panel, which allows you to create and open projects for all Ansoft products.To start the Maxwell Control Panel, double-click the Maxwell icon. The Maxwell Control Panel appears.

See the Maxwell Control Panel online documentation for detailed descriptions of other options in the Maxwell Control Panel. If the Maxwell Control Panel does not appear, refer to the Ansoft PC Installation Guide for possible reasons.Next you will create a new project directory in which to store the projects for the PExprt getting started guides.

2-2 Creating a PExprt Project


Start the Project ManagerYou can use the Project Manager to create, rename, or delete project files. The Project Manager also allows you to access projects created with other Ansoft products.To access the Project Manager, click PROJECTS in the Maxwell Control Panel.The Maxwell Projects window (the Project Manager) appears, listing the current path and any existing projects.



Create a Project DirectoryThe first step in using PExprt to model a magnetic component is to create a project directory and a project in which to save all the data associated with the problem.Project directories contain specific sets of projects created with Ansoft software, categorized in useful ways. For example, you might want to store all projects related to a particular feature or application in one project directory. The Project Manager should still be on the screen. You will now add the getstPExprt directory, which will contain the PExprt project you create using this getting started guide.

To create the project directory:1. Click Add from the Project Directories list at the bottom left of the Project Manager window.

The Add a new project directory window appears, listing available directories and subdirec-tories.

2. Double-click the sub-directory names until the current directory (at the top of the window) is the one where you want to locate the project.

3. Type getstPExprt in the Alias field. An alias is a project directory name that refers to the cur-rent directory. You can use aliases to refer to project directories located in different computer directories, or across network drive locations.

4. Click the Make New Directory radio button.5. Click OK.

The new getstPExprt project directory is created in the Project Directories list under the cur-rent default project directory.

Note If you have already created a project directory while working through another PExprt getting started guide, skip to “Create a Project” on page 2-5.



Create a ProjectNow that you have created the project directory, create a new project named BuckInductor.The Project Manager should still be on the screen, and the empty getstPExprt project directory should still be selected.To create a new project in the getstPExprt project directory:1. With the getstPExprt directory selected, click New from the Projects list.

The Enter project name and select project type window appears.

2. Type BuckInductor in the Name field.3. Select Maxwell PExprt Version 6 from the Type pull-down list.

The rest of the list displays other Ansoft products for which you have licenses.4. Type your name or user ID in the Created By field.

• If you are using Microsoft Windows NT, 2000, or XP, your login name is automatically entered here.

• If you are using another version of Windows, you may enter your user name or leave the field as is.

5. Deselect the Open project upon creation check box, allowing you to create the new project without immediately launching the software. This allows you to enter project notes before opening the project.

6. Click OK to create the new project. The project name appears in the list of projects in the getstart project directory. Because you created the project, the Status is set to Writable, indicating that you have access to the project.



Enter Project NotesIt is generally a good idea to save notes about the new project so that the next time you use PExprt you can view information about a project without opening it. To enter a description for this project:1. Leave Notes selected. This radio button is selected by default, and the Model option is dis-

abled for PExprt projects, which are only analytical and do not involve a physical model.2. Click in the Notes area (its border is highlighted). 3. Type the following in the Notes area:

This is a design of a Buck Converter Inductor using PExprt and the Inductor Design Example Getting Started Guide.

4. Click Save Notes.

You are now ready to open the new PExprt project and run PExprt.

Note Grayed-out text on commands or buttons means that the command or button is temporarily unavailable. The Save Notes button is grayed out unless there are changes to be saved in the Notes area.


3Accessing the Software

In the last chapter, you created the getstPExprt project directory and created the BuckInductor project within that directory. Now you will open that project in PExprt and start using the software.The goals for this chapter are to:• Open the project you just created and run PExprt.• Learn about the PExprt working window.• Specify your preferences — modeling language, stock libraries, and units.


Accessing the Software 3-1


Open the New Project and Run PExprtThe newly created BuckInductor project should still be highlighted in the Project Manager Projects list. If it is not, click to select it.To open the new project in PExprt:1. Click Open under the Notes area.

PExprt opens, and the Selection of Magnetic Component Type window appears.

2. Click the + symbol in front of Converter Based to expand the Inductor/Converter Based tree.

3-2 Accessing the Software


Three different types of converters appear in the tree: Buck, Boost, and Buck-Boost.

3. Select the Buck converter type, and click OK. The PExprt working window appears.



PExprt Working WindowThe PExprt working window is divided into four sections: the Input/Output Data area, the Ele-ments Information area, the Libraries area, and the Graphical Information area.

Input/Output Data AreaThe Input/Output Data area contains different tabs, depending on the design status. The following three tabs initially appear:• Waveforms: Use this tab to define the converter specifications and waveform inputs.• Design Inputs: Use this tab to define the design inputs.• Modeling Options: Use this tab to define the modeling options.Use this area to define inputs and other specifications. When you change parameters in the Input/Output Data area, the values for related parameters in that window are automatically updated. The graph is also automatically updated in the Graphical Information area.

ElementsInformation area

Libraries area

Input/Output Data area

Graphical Information area



Elements Information AreaThe Elements Information area contains information about each element included in the libraries. When you click an element in the library tree, its information is displayed in this area.

Libraries AreaThe Libraries area contains a tree with the stock and design libraries used in PExprt. Each library contains cores, bobbins, wires, insulators, and core materials. To view the elements included in each library, click the + symbol to expand the tree.

Graphical Information AreaThe Graphical Information area displays different type of graphical information, depending on the design status and which tab is selected in the Input/Output Data area.



PreferencesThere are several options you can specify before working with PExprt. When you click Options>Preferences, the Preferences window appears.

This window has three tabs:• Program Paths: Use this tan to specify the location of Maxwell 2D solver executable.• Modeling Language: Use this tab to specify the model language (Maxwell SPICE, PSpice,

Saber, or SIMPLORER) to be used to write the model netlists.• Stock Libraries: Use this tab to specify the libraries that you want to be opened with any new

design.These tabs are explained in the following sections.



Specify Program PathsPExprt generates magnetic component models that can be based on FEA calculations.To specify the path to the Maxwell 2D solver executable:1. Click Options>Preferences.

The Preferences window appears.2. Click the Program Paths tab.

3. Click the Maxwell 2D name to select it.4. Click Modify.

The Browse M2dfs Executable window appears.5. Find and select the m2dfs.exe executable, and then click Open to return to the Preferences

window.6. Click OK.



Specify Modeling LanguagePExprt generates magnetic component models to be used in four different electrical simulators: Maxwell SPICE, PSpice, SIMPLORER, and Saber.To specify the default modeling language:1. Click Options>Preferences.

The Preferences window appears.2. Click the Modeling Language tab

3. Click the Simplorer button to select SIMPLORER as the modeling language.4. Click OK.

Specify Stock LibrariesPExprt package includes different libraries in order to make easier you design process. Although you can open, close and save libraries during the magnetic component design, you can also select which libraries you want to be loaded with any new design.See Chapter 4, “PExprt Libraries,” for a detailed description of PExprt libraries.

Note The first time you use PExprt, all the libraries included with PExprt are loaded. If you make any changes, they apply the next time you open a new document.



To specify the default libraries:1. Click Options>Preferences.

The Preferences window appears.2. Click the Stock Libraries tab.

3. To load a new stock library:a. Click Add New.

The Browse Libraries window appears.b. Find and select the library you want to add, and click Open.

The new library appears in the list.4. To remove a library from the list:

a. Select a library from the Libraries to be loaded as “Stock” list.b. Click Remove.

The library is removed from the list. The next time you open a PExprt design, the removed library does not appear in the Stock Library tree.

5. Click OK.

Note In this example project, you do not need to add or remove any libraries in the Preferences window.



Units of MeasurementYou can also specify the unit of length you want to use in PExprt. For this example, you want to use millimeters.To specify millimeters as the unit of length:1. Click Options>Units.

The Units window appears.

2. Select Millimeters, and click OK.


4PExprt Libraries

PExprt works with libraries in order to select elements (for example, cores, wires, core materials) that you want to be considered during the design process. The goals for this chapter are to:• Learn about the types of libraries available in PExprt.• Work with PExprt libraries.


PExprt Libraries 4-1


Types of LibrariesPExprt libraries contain the cores, bobbins, wires, and core materials needed to design magnetic components. Two different types of libraries are available in PExprt: stock libraries and design libraries. They are displayed in the Libraries area, in the lower-left portion of the PExprt working window.

Stock LibrariesThese libraries are included with PExprt and are saved in the /PExprt_Install/Lib/PExprt direc-tory, where PExprt_Install is the location where you installed PExprt. Seven libraries are provided with the PExprt installation: • Ferroxcube (former Philips).• Epcos (former Siemens).• TDK.• Magnetics.• AVX.• Micrometals.• Steward.Stock libraries are locked, and you cannot modify them. Once you drag a stock library into the design library folder, the new copy is editable, but the original stock library remains locked.

User's Stock LibrariesYou can create your own stock libraries in order to introduce elements you commonly employ in your applications. These libraries can be composed of custom elements, as well as any of the ele-ments contained in the stock libraries. You can name, save, modify, and lock/unlock user stock libraries.

Design LibraryA project’s design library is the only library that is considered during the design process. All or part of the elements in this library are included during the design process. You specify a design library for your project by dragging a library from the stock library tree in the Libraries area of the PExprt working window.

Stock Libraries

User’s Stock LibraryDesign Libraries

4-2 PExprt Libraries


Working with LibrariesBefore designing a magnetic component, you first need to load stock libraries so that they appear in the Libraries area of the PExprt working window.

Opening Stock LibrariesThe first time you run PExprt, all libraries included with PExprt are loaded with any new project. You can change this using the Stock Libraries feature via the Options>Preferences menu, as explained in “Specify Stock Libraries” on page 3-8.To load additional stock libraries:1. Click the Libraries>Stock Libraries>Load Stock Library menu.

The Load Stock Library window appears.2. Select the library you want. PExprt libraries are typically located in .../pexprt6/Lib/PExprt.3. Click Open.

After you load a new stock library, that library appears under the Stock Libraries tree in the Libraries area.



Creating New Stock LibrariesTo create your own stock library, click Libraries>Stock Libraries>New Stock Library. A new library named User Library appears under the Stock Libraries tree.

Saving Stock LibrariesTo save a stock library:1. Click Libraries>Stock Libraries>Save Stock Library or Library>Stock Libraries>Save

Stock Library As. The Select Library window appears. Only user-created libraries appear in the list of possible libraries to be saved.

2. Select the library you want to save from the list, and click OK. The Save “User Library” As window appears.

3. Type a library name in the File name box, and click Save.

Closing Stock LibrariesTo close any of the stock libraries:1. Click Libraries>Stock Libraries>Close Stock Library.

The Select Library window appears.2. Select the library you want to close from the list, and click OK.



Saving the Design LibraryTo save the design library:1. Click Libraries>Design Library>Save Design Library or Library>Design Library>Save

Design Library As. The Select Library window appears.

2. Select the library you want to save from the list, and click OK.

Closing the Design LibraryTo close the current design library:1. Click Libraries>Design Library>Close Design Library.

The Select Library window appears.2. Select the library you want to close from the list, and click OK.

Modifying Elements in the LibrariesYou can modify elements contained in any unlocked library, allowing you to create your own ele-ments and customize your own libraries. To edit an element, double-click it. The Properties window for that element appears.

Library Element ParametersYou can modify the following library element parameters:1. Cores: When you double-click a core element (for example RM type), the properties window

appears.

• Click the Core Properties tab of this window to modify the effective values.• Click the Dimensions tab to modify the dimensions of this particular core.

Note You can drag-and-drop libraries from the Stock Libraries tree to the Design Library tree.



2. Bobbins: When you double-click a bobbin, the properties window appears.

• Use this window to modify the dimensions, the thermal conductivity, and the thermal emissivity for the selected bobbin.

3. Wires: When you double-click a wire (for example a ROUND one), a properties window for that element appears:

• Use this window to modify the dimensions, the thermal conductivity, and the thermal emissivity for the selected wire.



4. Material: When you double-click a core materials, a properties window appears for that ele-ment:

• Click the Electrical Properties tab of this window to modify the electrical parameters.• Click the Additional Parameters tab to introduce the losses parameters, the typical fre-

quency application range, dependency of the permeability with the magnetic field strength, the thermal conductivity and the thermal emissivity, as shown below:



• Click the Simplorer Non Linear Parameters tab to introduce the hysteresis curve defini-tion points and generate the Simplorer non linear core model parameters, as shown below:

• Click the Jiles Atherton Hysteresis Curve tab to visualize the hysteresis curve that is cal-culated with the current Jiles Atherton model parameters, as shown below:

Note If the PSpice modeling language is selected using Options>Preferences, the PSpice Non Linear Parameters tab appears instead of the Simplorer Non Linear Parameters tab.



• Click the Graphical Information tab to graphically represent the incremental permeabil-ity, core losses and the B-H curve, as shown below:

Creating New Library ElementsUse the Add New command on the shortcut menu to create a new element in an unlocked library.To create a new element:1. Right-click the element type. For example, to create a new PQ core, right-click the PQ label.

A shortcut menu appears.2. Select Add New from the shortcut menu.



A new PQ core, named New Core, appears at the end of the PQ cores list.

Copying Elements in the LibrariesYou can drag and drop elements from any stock library to the design library.

Note Elements are copied element by element; you cannot copy an entire type of elements. For example, it is not possible to copy all ETD cores from one of the stock libraries by drag-ging the ETD label. You must copy each individual ETD core.


5Selecting the Design Library

In Chapter 3 you opened the BuckInductor project, explored the PExprt working window, and reviewed the general procedure for creating a magnetic component design with PExprt. In Chapter 4 you learned how to work with PExprt libraries. You are now ready to start defining the project for the buck inductor design; the first step is to define the design library.The goals for this chapter are to:• Understand the role of the design library in the design process.• Define the design library for the buck inductor sample project.


Selecting the Design Library 5-1


Design Library RoleThe PExprt design engine calculates the power losses of all possible combinations of cores, wires, and cores materials that are selected using the specified design library. Using the design library, you can do the following:• Define design constraints by selecting part or only one of the cores, wires, and core materials

contained in the design library.• Consider multiple combinations of the various cores, wires, and core materials contained in the

design library.The design library contains the elements considered for the final design. Any element not included the design library is ignored during the design process.You can select the elements you want to include in the design library or allow PExprt to automati-cally select the elements for you, based on encoded design criteria described later. See “Auto-Select Feature” on page 5-5 for more information on how PExprt selects elements for you.

Selecting the Design LibraryYou select the design library by dragging one of the loaded stock libraries and dropping it onto the Design Library tree folder in the Libraries area of the PExprt working window. In this example, you are going to use the Ferroxcube library as the design library.To specify the design library, drag the Ferroxcube library from the Stock Library tree folder, and drop it onto the Design Library tree folder.A copy of Ferroxcube library, named Ferroxcube_Design, appears under the Design Library tree.

Note The stock libraries included with PExprt are locked and cannot be modified. Any library created by the user can be modified. Once you copy a stock library, into the design library folder, you can then modify the copied version.

5-2 Selecting the Design Library


Selecting Elements in the Design LibraryOnce you have specified a design library, you can identify constraints for your design by selecting particular elements to be considered in your design. If you skip this step, PExprt automatically selects these elements for you using the Auto-Select feature.This example guides you through selecting the core geometry yourself but allows PExprt to select the other elements (wires and core materials) using Auto-Select.To select elements for the core geometries:1. Expand the Ferroxcube_Design library tree by clicking the + symbol in front of its name.

2. Right-click the RM label. A shortcut menu appears.

3. Select Select All from the shortcut menu.



The RM icon turns green, indicating that part or all the RM sizes have been selected.

4. Expand the POT folder by clicking its + symbol.5. Right-click to individually select each of the following elements under POT:

• P26/16• P30/19• P36/22• P42/29

A tool icon appears next to each element that has been selected.

You can repeat steps 4 and 5 to select wires and core materials from the design library. In this example, we will allow PExprt to use the Auto-Select feature to specify those elements.

Note The bobbins are automatically selected once you have selected the cores. Only the bobbins with the same name as the cores are selected.



Auto-Select FeatureIf you do not select elements on your own from the design library, PExprt can do so for you using its Auto-Select feature. The Auto-Select feature is applied just before starting the design procedure, immediately after you click Calculations>Start Design Process.PExprt’s Auto-Select feature applies the following default selection criteria when selecting ele-ments:• Core Shapes:

• Inductors and Coupled Inductors: POT, RM, EE, and EP.• Transformers and Flyback: RM, EE, and ETD.• Planar components: RM, EE, and EI.• Toroidal components: Toroids.

• Core Sizes:• PExprt selects the size of the cores based on the power handled by the component.

• Wire Type:• PExprt selects solid cylindrical wires for concentric and toroidal designs, and selects toroi-

dal designs and planar conductors for planar designs.• Wire Area:

• PExprt selects one out of every three wires so that different diameters may be considered. • Core Materials:

• PExprt selects a maximum of three core materials, based on the frequency and amplitude of the first harmonic of the current waveform and its DC level.

Note If the current design library does not contain bobbins for the selected cores, the core shapes and sizes are selected according to the bobbin shapes and sizes of the design library.




6Converter Input Data

After you have selected the design library and the elements to be considered during the design pro-cess, you need to introduce the converter specifications. Converter specifications include input and output voltage, switching frequency, and current ripple.The goal for this chapter is to:• Enter converter specifications.


Converter Input Data 6-1


Waveforms TabTo enter converter specifications:1. Click the Waveforms tab in the Input/Output Data area of the PExprt working window.

The Waveforms tab appears.

2. Type 42 in the Input Voltage field, and select V as the units.3. Type 200 in the Switching Frequency field, and select kHz as the units.4. Type 12 in the Voltage field under Output Values, and select V as the units.5. Type 300 in the Power field under Output Values, and select W as the units.6. Type 4.29 in the Ripple Value field under Inductor Current Ripple, and select A as the

units.7. Click File>Save to save the project. Accept the default location for the project file, and then

click Save.

6-2 Converter Input Data


The window now contains the following values:

Note The current ripple can be introduced either by the absolute value or by the percentage with respect to the average current. When you introduce the value using one of these approaches, the other value is automatically updated when you refocus.

Note Fields that cannot be updated (non-editable) are updated each time you enter a value in an editable box and refocus.

Converter Input Data 6-3


Graphical Information AreaThe Graphical Information area is used to represent the converter topology and the current and voltage waveforms applied to the inductor under design.

• Converter Topology: This is a static bitmap representing the topology of the converter with the inductor (blue box) under design.

• Waveforms: The waveform shape and values are updated each time you introduce a value in the edit boxes and refocus.

After you have introduced the values for this example, the waveforms appear as shown below:

PExprt is designed to automatically switch between continuous and discontinuous conduction mode as a function of the converter specifications. For example, if you introduce 20 W as the value for the output power in the previous example, the waveforms change to discontinuous conduction mode.

If you try this, remember to change the output power back to 300 W in order to continue with this example.

6-4 Converter Input Data

7Design Inputs

After you have selected the design library and introduced the specifications for the converter, as described in Chapter 6, “Converter Input Data,” you are ready to design the component and can go on to Chapter 9, “List of Results.” However, before you do so, you may want to customize your design by introducing several optional design inputs.The goal for this chapter is to:• Learn how design parameters impact the final design.


Design Inputs 7-1


Design Inputs TabTo enter design inputs:1. Click the Design Inputs tab in the Input/Output Data area of the PExprt working window.

The Design Inputs tab appears.

2. For this example, keep the default values.

7-2 Design Inputs


Design ParametersThe Design Inputs tab is shown below with the default values:

These parameters impact the final PExprt design as explained below:

Parameter Available Options Design ImpactGap Position Central Leg

Both LegsNone

Since the fringing energy of the gap can be considered during the design process, the position of the gap determines the value of the gap length. When you select None, PExprt tries to meet the specifications with no gap inclusion.

Geometry Concentric ComponentPlanar ComponentToroidal Component

The selected geometry type is applied for the design.

Permeability Permeability as a function of H When you select this option, PExprt considers the permeability constant or a function of the magnetic field strength. You can set the permeability to depend or not depend on H through the Core Material elements of the design library.

Bobbin Include If this option is not selected, PExprt presents designs with no bobbin. By default, concentric components include a bobbin, while planar components do not. Toroidal components never include a bobbin.

Gap Consider Fringing Gap Energy If this check box is selected, PExprt considers the energy around the air gap region (fringing energy) for the air gap length calculation. If the design has no air gap, this parameter is irrelevant.

Design Inputs 7-3


Fixed Value If this check box is selected, PExprt only looks for designs with this particular gap value. Therefore the gap is not a degree of freedom, and the resulting designs might not present exactly the value of inductance specified in the Waveforms tab.

Winding Setup

2D Winding Setup1D "Completely-Full"1D "Partially-Full"

This parameter determines the most feasible winding strategy in order to create the setup you specify (i.e., to create a 1D analytical-based model or a 2D FEA-based model). The following types of models are available:• 2D Winding Strategy: PExprt allows more

than one winding in the same layer. For example, two parallel windings may be placed in the same layer.

• 1D “Completely-Full”: PExprt fills the layers with turns, filling the entire window height.

• 1D “Partially-Full”: PExprt allows layers partially filled with turns.

Thermal Parameters

Ventilation:• Low• Normal• High

This value determines the film coefficient for the radiation of temperature. Low means close environment, while High means forced ventilation. When you select Low, you obtain a higher temperature rise than when you select High for the same specifications.

Radiation & Convection If this option is selected, PExprt calculates the temperature value taking into account the radiation and convection effects in the core window.

Ambient Temperature PExprt presents solutions assuming that the ambient temperature is the option specified in this field.

7-4 Design Inputs


Winding Efficiency

Awire/Awinding (Wire area/Winding area)Spacing

The parameter determines how to modify the wire spacing. The smaller the winding spacing, the fewer number of wires that fit in the window.

Limit Values • Maximum Temperature • Bsat/Bmax: This value is

specified as a percentage of the saturation flux density. (PExprt is not designed to provide components working above saturation value of the flux density.)

• Maximum Gap: This value is specified as a percentage of the window height.

• Maximum Parallel Turns

• Maximum Number of Layers: This value is particularly useful in the design of planar components, where the cost of the components depends strongly on the number of layers.

• PExprt presents solutions with a temperature rise below the Maximum Temperature value.

• Bsat/Bmax is the maximum value of flux density PExprt considers for the calculations.

• PExprt presents solutions with a gap length below the Maximum Gap value.

• PExprt uses the Maximum Parallel Turns value for the maximum number of parallel windings to be considered during the design process.

• PExprt uses the Maximum Number of Layers value for the maximum number of layers to be considered during the design process.

Margin Tapes

% Window Height% Window Width

PExprt presents solutions with the specified top and central margin tape percentages, as shown below:

Top Margin Tape

Central Margin

Design Inputs 7-5


Graphical Information AreaThis area of the PExprt working window is used to represent the waveform of the voltage and cur-rent applied to the inductor under design. These waveforms are the same as the ones on the Wave-forms tab but are represented using two separate graphs.See “PExprt Working Window” on page 3-4 for a description of the working window.

7-6 Design Inputs

8Modeling Inputs

After you have selected the design library and introduced the specifications of the converter, as described in Chapter 6, “Converter Input Data,” you are ready to design the component and can go on to Chapter 9, “List of Results.” However, before you do so, you may want to introduce several optional modeling options, in order to improve the accuracy of the results.The goal for this chapter is to:• Learn how modeling options impact the final design.


Modeling Inputs 8-1


Modeling Options Tab of Input/Output Data AreaTo enter modeling options:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow. The Modeling Options tab appears.

2. For this example, use the default values.

8-2 Modeling Inputs


Modeling ParametersThe Modeling Options tab is shown below with the default values:

These parameters impact the final PExprt design as explained below:

Parameter Available Options Design ImpactWinding Losses Calculation

Irms and DC ResistanceHarmonics and AC Resistance (Skin)Harmonics and AC Resistance (Dowell)Number of harmonics:

If you account for the Harmonics in the losses calculation, you can specify how many harmonics you want to be considered during the design process. You can introduce this information specifying the number of harmonics or by means of the relative influence of one harmonic with respect to the previous one.

During the design process, there are three possible ways to calculate the losses in the conductors:• Irms and DC Resistance: Winding losses are

calculated as:P = I2rms * RDC

• Harmonics and AC Resistance (Skin): Winding losses are calculated as:P = I2DC * RDC + I

2rms_1 * RAC_1 +

I2rms_2 * RAC_2 + I2rms_3* RAC_3 + ...

(where Irms_i is the rms value of the harmonic i, and RAC_i is the resistance at the frequency of the harmonic i calculated with the effective area, accounting for the skin effect at each frequency).

• Harmonics and AC Resistance (Dowell): Winding losses are calculated as:P = I2DC * RDC + I

2rms_1 * RAC_1 +

I2rms_2 * RAC_2 + I2rms_3 * RAC_3 +

...(where Irms_i is the rms value of the harmonic i, and RAC_i is the resistance at the frequency of the harmonic i, calculated with the Dowell equations).

Modeling Inputs 8-3


Core Losses Calculation

SteinmetzJiles Atherton (Hysteresis)Jiles Atherton (Hysteresis) + Eddy

During the design process, there are three possible ways to calculate the losses in the conductors:• Steinmetz: Core losses are calculated as:

Pcore = fα * Bβ ∗ Vol

• Jiles Atherton (Hysteresis): Core losses are calculated using Jiles Atherton model. Therefore, only hysteresis losses are considered.

• Jiles Atherton (Hysteresis) + Eddy: Hysteresis core losses are calculated using Jiles Atherton model. Eddy current losses in the core are calculated as:PEddy_core = (U

2rms*leff)/(8*π ∗ ρ ∗ N2)

Optimize number of turns for minimum losses

No OptimizationApply Optimization (for Mode 1 or Mode 2)

If you select No Optimization, PExprt does not iterate to find the lower losses solution for each combination of core/wire/material. If you select Apply Optimization, PExprt optimizes using two possible approaches (Mode 1 or Mode 2). Click More Info to learn more about the two approaches.

8-4 Modeling Inputs


List of Results

Show all solutionsSelection

PExprt calculates all solutions meeting the initial specifications, but you can configure which ones to present. If you select Show all solutions, PExprt shows all meeting specifications. If you select Selection, only those that meet the selection criteria are included on the List of Results tab.To modify the default selection criteria, click the Select Solutions button. In the window that appears, you can specify how the results will be classified (by loss, temperature rise, volume, height, or footprint) and the number of solutions to be shown.

Selection of elements from the Design Library

Apply RestrictionsNo Restriction (all possible configurations)

If you want to use all the elements you have selected in the design library for the design process, select No Restrictions. However, if you have selected many elements in the design library, and you do not know how many of them make sense to be considered in the design, select Apply Restrictions to allow PExprt to select the appropriate elements for your design. You can configure how restrictive the criteria are for the selection by clicking the Configure button. In the window that appears, use the Design Constraints tab to set the restriction level for the selections.To learn more about how PExprt applies restrictions, click the Information tab.

Modeling Inputs 8-5


Graphical Information AreaThis area of the PExprt working window is used to represent the waveform of the voltage and cur-rent applied to the inductor under design. These waveforms are the same as the ones on the Wave-forms tab but are represented using two separate graphs.See “PExprt Working Window” on page 3-4 for a description of the working window.

8-6 Modeling Inputs

9List of Results

You are now ready to generate designs and explore the solution results.The goals for this chapter are to:• Generate the design alternatives.• Classify the designs using the List of Results tab in the Input/Output Data area of the PExprt

working window.


List of Results 9-1


Starting the Design ProcessDo the following to start the design process:1. Click Calculations>Start Design Process.

The Auto-Select feature is applied for any elements you did not previously select in the design library.

2. Click Yes when you are asked if you want to auto-select wires and core materials. The Designing Magnetic Component progress window appears.

When the design process is complete, a design report message appears, telling you how many valid designs were obtained from the total number of analyzed designs. In this particular case, PExprt tells you it has obtained 169 valid results out of 1139 analyzed designs. Since you selected Solution Selection on the Modeling Options tab, only the 10 best solutions, in terms of losses, are shown.

3. Click OK to close this window.

9-2 List of Results


The list of results appears on the List of Results tab of the Input/Output Data area:

List of Results 9-3


Using the List of Results TabThe List of Results tab, in the Input/Output Data area, displays the results of the design process.

The meaning of the icons in front of each design is as follows:

To configure the List of Results tab:1. Click on the header of one of the columns to do one of the following:

• Classify that column in ascending or descending order.• Select that particular column to be graphically represented in the Graphical Information

area.

Note The columns containing alphanumerical values will not be graphically represented.

This design presents a 2D winding strategy


The losses of this design have been recalculated using FEA calculations

The losses of this design have been recalculated using PEmag 1D model

All specifications have not been fulfilled (for example magnetizing inductance value). This design presents a 2D winding strategy




The losses of this design have been recalculated using FEA calculations

The losses of this design have been recalculated using PEmag 1D model



9-4 List of Results


2. Double-click any of the designs in the list. The Customize List of Results window appears.

Using this window, you can do the following:• Show or hide columns.• Specify the range of values to represent elements in each column.

3. To present solutions with a gap larger than 0.75 mm, type 0.75 in the Gap field in the Mini-mum column.

4. Click OK to apply the criteria to the List of Results tab.The List of Results tab presents only solutions with a gap larger than 0.75 mm, as can be seen below.

List of Results 9-5


Graphical Information AreaThis area of the PExprt working window is used to graphically represent the information for one of the columns from the List of Results tab in the Input/Output Data area. Initially, the power losses are represented for all the design solutions included on the List of Results tab.

See “PExprt Working Window” on page 3-4 for a description of the working window.

9-6 List of Results

10Performance Results

After generating various designs for this particular example, you are now ready to explore the results that PExprt provides for each design on the List of Results tab.The goal for this chapter is to:• Explore the Performance Results tab.


Performance Results 10-1


Selecting a DesignAll the design alternatives on the List of Results tab meet your specifications. Now you need to select one of them, so that you can explore its performance results.To explore performance results for a specific design:1. Click the List of Results tab.2. Click on the header for the Power Losses column to classify the list by power loss.

3. Select the lowest loss design.

Note To reverse the order (ascending/descending), click on the column header again.

10-2 Performance Results


4. Click the Performance Results tab.

Note The results presented on the Performance Results tab correspond only to the design cur-rently selected on the List of Results tab.



Exploring the Performance ResultsYou are now ready to explore the performance results of the currently selected design.This window contains the following sections:• Input/Output Data area: Used to show the numerical values of the performance results.

• Graphical Information area: Used to graphically represent the following parameters:• Power Losses distribution: The ratio between core losses and wire losses. • Window Filling: The ratio between the total wire area in the window and the total air area

in the window.• Window Rate: The ratio between the total winding area (area of the window where the

winding is placed, included the air among turns) and the area of the window where there is no winding.



The following performance results parameters are shown on the Performance Results tab in the Input/Output Data area of the PExprt working window:1. Losses considering selected model:

• Core: The losses in the core of the magnetic component under the defined working condi-tions. To explore the core losses in more detail, click the Core value display button. When you click this button, the Core Losses window appears, describing how the core losses are calculated (using the Steinmetz equation).

• Winding: The losses in the winding, applying the model that you selected on the Model-ing Options tab. In this example, you are considering the skin effect of each harmonic. To explore the winding losses in more detail, click the Winding value button. The Winding AC Information window appears, displaying a plot of the winding resistance as a func-



tion of the frequency.

You can change the frequency range of the plot using the Min Freq. and Max Freq. fields.Click the AC Losses tab to plot the contribution of each harmonic to the total winding losses.



Click the Current FFT tab to plot the Fast Fourier Transformation of the current waveform. This information represents the harmonic content of the current waveform.

• Total: The total of the core and winding losses added together.2. Winding losses (with DC Resistance):

• DC Resistance: The DC resistance of the winding. To explore the DC resistance in more detail, click the DC Resistance value or the DC Losses value. The Winding DC Infor-



mation window appears.

• Irms: The root medium square (rms) value of the current waveform.• DC Losses: The DC losses in the windings under the defined current waveform. To learn

about how this value is calculated, click the DC Losses value. The Winding DC Infor-mation window appears, listing a detailed explanation about the DC losses calculation.

3. Window Occupancy:

• Window Filling: The ratio between the total wire area in the window and the total air area in the window.

• Window Rate: The ratio between the total winding area (area of the window where the winding is placed, including the air among turns) and the area of the window where there is no winding.

4. Additional Parameters:

• Current Density: Current density in the winding (rms current value divided by the cross section area of the wire). Parallel wires are taken into account.

• Inductance: The inductance of the final design. PExprt tries to fit this value to the speci-fied one.



5. Temperature:

• Max Temperature: The maximum temperature (the hottest point) in degrees centigrade taking into account the ambient temperature.

• Core Temperature: The maximum temperature in the core (the hottest core point) in degrees centigrade taking into account the ambient temperature.

6. Flux Density:

• Variation of B: The variation of the flux density in mT (teslas * 10-3).• Maximum B: The maximum value of the flux density in mT (teslas * 10-3).

7. Incremental Permeability:

• Havg: The average value of the Magnetic Field Strength in Amperes/meter.

Note PExprt is not designed to provide designs above saturation flux density. Therefore, the maximum B value always presents a value below the saturation B value.



• Permeability: The value of the permeability that has been used in the current design.Initial The initial value of the relative permeability defined in the Core Material

library for this particular core material.

Actual The actual value of the relative permeability used in the design process, which accounts for the DC flux level. Since in this example you have not considered the DC flux level in the permeability value, this value is the same as the initial permeability.

Note To account for the DC flux level in the permeability calculation, you need to select the Permeability as a function of H check box on the Design Inputs tab.


11Constructive Results

By now you have generated the designs for this particular example, and you have explored the Per-formance Results tab in the Input/Output Data area of the PExprt working window. You are now ready to explore the Constructive Results tab, which PExprt provides for each design on the List of Results tab.The goal for this chapter is to:• Explore the Constructive Results tab.


Constructive Results 11-1


Exploring the Constructive ResultsTo view the constructive results:• Click the Constructive Results tab in the Input/Output Data area of the PExprt working

window. The following window appears, displaying the Constructive Results tab in the Input/Output Data area and the cross-section of the current design in the Graphical Information area:

Note The results presented on the Constructive Results tab correspond to only one design — the design that is currently selected on the List of Results tab.

11-2 Constructive Results


The following constructive results parameters are shown on the Constructive Results tab in the Input/Output Data area of the PExprt working window:1. Component:

• Core Size: The core size and name for the selected design.• Bobbin: The bobbin size and name for the selected design.• Core Material: The core material name for the selected design.• Wire: The wire gauge (AWG) and name for the selected design.• Library: The name of the library that has been used as the design library for the selected

design.

Note You can explore the constructive elements by clicking on the element button. For example, to explore the core, click the P42/29 button.

Constructive Results 11-3


2. Parameters:

• Gap: The air gap length for the selected design.• Number of Turns: The number of turns for the selected design.• Parallel Turns: The number of parallel turns for the selected design.

11-4 Constructive Results

12Generating Models

PExprt includes an advanced modeling package that enables you to create accurate models of the generated designs. The Modeling module allows you to generate analytical-based or finite element-based models. You can link directly between the design module (PExprt) and the modeling module, as described in Chapter 15, “Using PExprt with the Modeling Module.”Alternatively, if you want to quickly generate a design model without opening the Modeling mod-ule, you can use the modeling feature of PExprt, which uses the same modeling generation engine.In this chapter you will learn how to generate both, analytical and FEA-based models.The modeling strategy used to generate analytical models is based on analytical expressions. This approach can be applied only to magnetic component designs that present a one-dimensional (1D) field distribution. This feature is only enabled if the selected design presents a 1D field distribution.The modeling strategy based on FEA calculations can be applied to all obtained designs.

Note Magnetic components with a single conductive sublayer in each layer can be modeled using an analytical-based model. If the magnetic component contains more than one con-ductive sublayer per layer, only FEA-based modeling can be used through the Modeling module. If the modeling feature is grayed-out, then the selected design cannot be modeled using analytical expressions.

Note The influence of the fringing flux in components with an air gap is a clear 2D effect. Although the analytical-based model accounts for the energy around the air gap, the influ-ence of this effect on the resistance is not considered in the analytical model approach.

Generating Models 12-1


the

Since the selected design in this example presents a 1D field distribution, you can generate the ana-lytical model from PExprt without forcing PExprt to do so.The goals for this chapter are to:• Define the model language (Maxwell SPICE, PSpice, Saber, or SIMPLORER).• Generate the analytical-based model.• Generate the FEA-based model.

Note You can force PExprt to provide 1D designs using the Winding Setup parameter onDesign Inputs tab.


12-2 Generating Models


Defining the Modeling LanguageTo define the modeling language:1. Click Options>Preferences.

The Preferences window appears.2. Select the Modeling Language tab.

3. Click Simplorer to select it as the as modeling language.4. Click OK to apply the selection and close the window.



Generating the ModelThis section explains how to generate both model types, analytical and FEA-based.

Generate the Analytical ModelDo the following to generate the analytical model:1. Select the first design from the List of Results tab.

2. Click the Modeler>Generate Model menu option. The Model Generation window appears.

3. Select Generate Analytical Model in order to generate the analytical model of the selected design.

4. Click OK to generate the model. A message appears, telling you that the 1D model has been successfully generated.

5. Click OK to close this message. A message appears, telling you the path to the 1D model netlist.

6. Click OK to close this message.You can now use this model in SIMPLORER as any other circuit element. See Chapter 16, “Link-ing with SIMPLORER,” for additional information.



View the Model NetlistTo explore the model netlist:1. Click Modeler>View Analytical Model Netlist>Simplorer.

Windows Notepad opens, displaying the SIMPLORER netlist description.

2. After viewing the netlist description, click File>Exit to exit Notepad.



Generate the FEA-based ModelTo generate the FEA-based model:1. Select the second design from the List of Results tab.

2. Click Modeler>Generate Model.The Model Generation window appears.

3. Select Generate FEA based Model (without capacitive effects) in order to generate the FEA-based model of the selected design.

4. Click the OK button to generate the model. A message appears, telling you that the magnetic component contains windings connected in parallel.

5. Click OK to close this message.



The UPM FEA Modeler window appears.

6. Click the Start button to start the FEA-based model generation. The model generation should take approximately 2 minutes. After the FEA-based model generation procedure finishes, a message appears telling you that the parameter extraction is completed.

7. Click OK to close this message. A second message appears telling you the path to the 2D model netlist.

8. Click OK to close this message. The UPM Mgen window appears.

9. Explore the results in order to check the accuracy of the curve fitting process. Select each impedance in the View Impedance list box.



10. Click Exit in the UPM Mgen window to close it.

11. Click Exit in the UPM FEA Modeler window to close it.

You can now use this model in SIMPLORER as any other circuit element. See Chapter 16, “Link-ing with SIMPLORER,” for additional information.



View the Model NetlistTo explore the model netlist:1. Click Modeler>View FEA based Model Netlist>Simplorer.

Windows Notepad opens, displaying the SIMPLORER netlist description.

2. After viewing the netlist description, click File>Exit to exit Notepad.



Recalculating Winding LossesYou can recalculate winding losses in two ways:• Using the models for both designs included in the list of results.• Using the FEA solver solution.

Using the Models to Recalculate Winding LossSince you generated the model for two of the designs included in the list of results, you can use those models to recalculate the winding losses. Since the models you generated are more accurate than the analytical loss models used by PExprt during the design process, the results you obtain recalculating the losses with the model information should be more accurate.To display the Customize List of Results window:1. Set the Minimum Gap to 0.2. Select the ID # check box. 3. Click OK.

The following ten results appear:

To recalculate the winding losses using the models:• Click Calculations>Recalculate Winding Losses.

A message window appears asking you whether you want to use the FEA solver to recalculate the losses. Since you want to use the previously generated models to recalculate the losses click No to continue.The list of results is updated with the new losses calculation.The losses calculation using the models is more accurate; therefore, the two designs with the losses recalculated are now at a different position. The meanings of the icons are explained in chapter 9.



Using the FEA SolverThe second way to recalculate winding losses is by using the FEA solver solution. If you want to recalculate the winding losses of the entire list of results using the FEA solver, you can use this approach. To reduce the time for this example, you will remove some designs from the list of results before calculating the losses.To recalculate the winding losses using the FEA solver:1. Click the Window Filling column header to sort the list.2. Remove the last six designs by clicking each row and pressing the Delete key. Click OK when

asked if you are sure you want to remove a design from the list.

The list of results should now contain the following four designs:

3. Click Calculations>Recalculate Winding Losses. A message window appears asking if you want to use the FEA solver to recalculate the losses.

4. Click Yes to continue.

Note The six designs to remove have the following power losses:• 0.4986• 0.5689• 0.5758• 0.6070• 0.7019• 0.7183



The UPM FEALossesCalc window appears.

5. Click Start to start the losses calculation. The total process should take approximately 7 min-utes to complete. When the process complete, click Exit to close the window.

The list of results is updated with the new losses calculation. Click the Temperature column header in the table to make sure the lowest temperature design is in the top row.


13Linking with Maxwell

All PExprt designs can be analyzed using Ansoft’s FEA solver, Maxwell 2D.The PExprt package includes licenses for the Maxwell 2D Eddy Current solver and the Maxwell Electrostatic solver. If Transient and Thermal licenses are purchased, PExprt can also link with them.The combination of PExprt, the Modeling module, and Maxwell 2D provides a unique, powerful way to design and analyze magnetic components.The goal for this chapter is to:• Use Maxwell 2D solver to analyze the designs.

Note Refer to the Maxwell 2D online help and getting started guides to learn how to use the software in detail.

Note Licenses for the Maxwell Eddy Current and Electrostatic solvers are included in the PExprt package. Therefore, you do not need to purchase additional licenses to link with them.However, licenses for the Maxwell Transient and Thermal solvers are not included in PExprt package. A separate license must be purchased to be able to link with these two solvers.


Linking with Maxwell 13-1


Linking with Maxwell Eddy Current SolverTo link with the Maxwell eddy current solver:1. Select the first design from the List of Results tab.

2. Select FEA Link>Eddy Current. The FEA Eddy Current Link window appears.

3. Click Solve Maxwell 2D Eddy Current Project (at highest frequency), and click OK to solve the project.

13-2 Linking with Maxwell


4. To explore the solution, click FEA Link>Eddy Current again.

5. Click Show Flux Distribution Map, and click OK to continue.The Maxwell 2D Post Processor appears with the flux distribution map.

6. Click File>Exit, and click Yes to close the Maxwell 2D Post Processor.



Linking with Maxwell Electrostatic SolverTo link with the Maxwell electrostatic solver:1. Select the first design from the List of Results tab.

2. Click FEA Link>Electrostatic. The FEA Electrostatic Link window appears.

3. Select Solve Maxwell 2D Electrostatic Project, and click OK to solve the project.4. To explore the solution, click FEA Link>Electrostatic again.



5. Select Show Energy Distribution Map, and click OK to continue.

The Maxwell 2D Post Processor appears with the energy distribution map.

6. Select File>Exit to close the Maxwell 2D Post Processor.



Linking with Maxwell Transient Solver

To link with the Maxwell transient solver:1. Select the first design from the List of Results tab.

2. Click FEA Link>Transient. The FEA Transient Link window appears.

3. Click Solve Maxwell 2D Transient Project, and click OK to solve the project.

Note The Maxwell Transient solver license is not included in the PExprt package. A separate license must be purchased to be able to link with it.



4. To explore the solution, click FEA Link>Transient again.

5. Click Plot Power Loss vs Time, and click OK to continue.Ansoft PlotData appears with the power losses vs time plot.

6. Click File>Exit to close Ansoft PlotData.



Linking with Maxwell Thermal Solver

To link with the Maxwell thermal solver:1. Select the first design from the List of Results tab.

2. Click FEA Link>Thermal. The FEA Thermal Link window appears.

3. Click Solve Maxwell 2D Thermal Project, and click OK to solve the project.

Note The Maxwell Thermal solver license is not included in the PExprt package. A separate license must be purchased to be able to link with it.



4. To explore the solution, click FEA Link>Thermal again.

5. Click Show Temperature Distribution Map, and click OK to continue.The Maxwell 2D Post Processor appears with the temperature distribution map.

6. Click File>Exit to close the Maxwell 2D Post Processor.




14Analysis Mode

So far you have been working with PExprt in Design Mode. An alternative way to work with PEx-prt is called Analysis Mode. Analysis Mode works with only a single design, which you select from the List of Results tab. After selecting a design, you may want to change a particular parameter of this design and then evaluate the impact of this change on the performance results. This can be done using Analysis Mode. You can also use Analysis Mode to evaluate previous designs with PExprt. In other words, if you have previously designed a magnetic component and you want to evaluate the losses, tempera-ture rise, and other factors of this design, you can use Analysis Mode to introduce this design and then obtain its performance results.The goal for this chapter is to:• Select and work with Analysis Mode.


Analysis Mode 14-1


Selecting Analysis ModeAnalysis Mode works with the design you have previously selected from the List of Results tab. Make sure that you have selected the lowest temperature design from the List of Results tab before continuing with the example.

To select Analysis Mode:1. Click Calculations>Analy7sis Mode.

Since you have previously recalculated the losses using the FEA solver, a message appears telling you that information will be deleted.

2. Click Yes to continue. The Constructive Results tab appears, showing the cross-section of the selected design. You can edit several values on the Constructive Results tab: the gap length, the number of turns, and the number of parallel turns.

To modify one of the constructive results values in order to evaluate its impact on the design:1. Change the Gap to 0.5 mm (instead of the current 0.43 mm in the gap length box).

2. Click Calculations>Analyze Component to evaluate the results. The Performance Results tab appears, showing the results for the modified design.

Note There is no design library when working in Analysis Mode. Therefore, the Design Library folder in the library tree is hidden while you are working in this mode.

14-2 Analysis Mode


Increasing the gap length from 0.43 mm to 0.5 mm has modified the inductance from 10 µH in the original design to 8.94 µH in the modified design. You can modify all of the constructive parameters by working in Analysis Mode.

To modify the remaining of the constructive parameters:1. Click the Constructive Results tab.2. Click the Cores tab in the Libraries area.

3. Expand the Ferroxcube library.4. Expand the POT core type.5. Drag the P30/19 core, and drop it on the area where the cross-section of the magnetic compo-

nent is represented (in the Graphical Information area). The new core is represented as shown below:

6. Click the Bobbins tab in the Libraries area.7. Expand the Ferroxcube library.8. Expand the POT bobbin type.9. Drag the P30/19 bobbin, and drop it on the area where the cross-section of the magnetic

Analysis Mode 14-3


component is represented. The new cross-section is represented as shown below:

10. Click the Wires tab in the Libraries area.11. Expand the Ferroxcube library, and then expand the ROUND wire type.12. Drag the AWG12 wire, and drop it on the area where the cross-section of the magnetic compo-

nent is represented. The new cross-section is represented as shown below:

After modifying the constructive parameters, save the project and evaluate the results.To save the project, click File>Save.To evaluate the results, click Calculations>Analyze Component. The Performance Results tab appears, showing the results for the modified design.

Note If you save the project while working in Analysis Mode, the project is saved in this mode, along with any design modifications you have applied to the selected design.

14-4 Analysis Mode

15Using PExprt with the Modeling Module

As already mentioned, the PExprt package includes a powerful Modeling module (PEmag), which allows you to generate models of the designs created using PExprt. The Modeling module allows you to modify the winding setup of the current design in order to evaluate the impact of different constructive parameters. Using the Modeling module you can:• Optimize the design by generating a new model using another winding strategy.• Compare different winding strategies in order to reduce parasitics (leakage inductance, AC

resistance, and capacitances).• Quantify the effect of the manufacturing tolerances.• Quantify the effect of the material tolerances.• Perform sensitivity analyses.• Analyze the impact of your design on the behavior of the entire circuit (voltage spikes, effi-

ciency, and ringing).You can work with the Modeling module as an additional add-on module within PExprt or as a standalone application.The goals for this chapter are to:• Link PExprt with the Modeling module.• Extract information from the model generated with the Modeling module.


Using PExprt with the Modeling Module 15-1


Invoking the Modeling ModuleYou can only invoke the Modeling module after you have selected a design or if you are working in analysis mode.To invoke the Modeling module:1. Click Modeler>Generate Model.

The Model Generation window appears.

2. Since the default option is Open PExprt Modeler (PEmag), click OK to continue. Since you are working in Analysis Mode, the Modeling module opens the current design that you previously modified, as shown below:

15-2 Using PExprt with the Modeling Module


Generating a Model with the Modeling ModuleTo evaluate the impact of the gap in your PExprt design, you are going to generate the FEA-based (2D) model of the current design in the Modeling module.You can invoke the Modeling module to obtain an accurate model and then use that model as feed-back for PExprt to recalculate the losses.You will learn how to generate the FEA-based model (2D) for two variations of the same PExprt design:• Windings close to the gap (initial PExprt design).• Windings far away from the gap (modified design).The impact of the gap on the converter losses can be explored and quantified using PExprt, without any manufacturing or measuring iteration.First, generate the FEA-based model of the current design. To generate the FEA-based model using the Modeling module:1. From within the Modeling module, click Modeler>FEA based Modeler (2D)>Start 2D

model generation. The UPM FEA Modeler window appears.

2. Click Start to start the FEA-based model generation. The model generation should take approximately 2 minutes. After the FEA-based model generation procedure finishes, a message appears telling you that the parameter extraction is complete.

3. Click OK to close this message. A second message appears telling you the path to the 2D model netlist.

4. Click OK to close this message. The UPM Mgen window appears.



5. Click Exit in the UPM Mgen window to close it.

6. Click Exit in the UPM FEA Modeler window to close it.

Select File>Exit to close the Modeling module and return to PExprt.You have generated the model of the current design using the Modeling module’s FEA-based model engine. This model accounts for frequency effects (skin and proximity) more accurately than PExprt models.



Using Models from the Modeling Module in PExprtIn Chapter 12, “Generating Models,” you learned how to recalculate the winding losses directly in PExprt using models generated from the Modeling module. In this section you will learn how to do the same thing working in Analysis Mode.After you have generated the FEA-based model with the Modeling module, you can use this model to calculate the losses in PExprt.To use the Modeling module’s FEA-based model for the losses calculation in PExprt:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow.

2. Select PEmag FEA based Model from the Winding Losses Calculation section.

3. Click OK to close this window. The Performance Results tab appears, showing the results. If you select Harmonics and AC Resistance (Skin) on the Modeling Options tab for this design, you obtain the losses shown below:

However, if you select PEmag FEA based Model on the Modeling Options tab for this design, you obtain the losses shown below:

Note The PEmag Analytical Model and PEmag FEA based Model options are disabled if the model from the Modeling module has not been previously generated.



Since the PExprt package includes the Modeling module, you can modify the winding strategy in order to evaluate the impact on your design.

Return to the Modeling module to modify the winding strategy.To modify the winding strategy in the Modeling module:1. Select Modeler>Generate Model, select Open PExprt Modeler (PEmag), and click OK.

Select No to overwrite the existing project.2. Select the Windings tab in the library tree area of the Modeling module3. Expand the Component Library element.

4. Double-click the Winding Setup element.

Note In the Modeling module (PEmag), avoid the following:• Changing the number of windings.• Adding or removing the bobbin.• Assigning a wire type of Twisted.If you change these settings, incorrect results will be returned to PExprt. If you do not plan to evaluate the results with PExprt after modifying the design in the Modeling module, then you can change any settings in the Modeling module.



5. Type 2.5 in the Central Margin Tape box.

6. Click OK to close the window. The new winding strategy appears.

7. Select File>Save, and remove the previous 2D model files.

You are now ready to generate the analytical model again with the Modeling module.1. In the Modeling module, click Modeler>FEA based Modeler (2D)>Start 2D Model Gener-

ation. The UPM FEA Modeler window appears.

2. Click Start to perform the simulation.Repeat the steps described in the previous section in order to generate the FEA-based model with the Modeling module. When done, select File>Exit to return to PExprt.Compare the results using this winding strategy with the ones previously obtained.As shown previously, to use an FEA-based model from the Modeling module for the losses calcula-tion in PExprt, do the following:1. Click the Modeling Options tab in the Input/Output Data area of the PExprt working win-

dow.2. Select PEmag FEA based Model from the Winding Losses Calculation section



3. Click Calculations>Analyze Component to evaluate the results. An information window appears.

4. Click OK to close this window. The Performance Results tab appears, showing the results.

Summary of ResultsThe results are explained below, for the three different situations: • PExprt analytical. Winding close to the gap.

• Modeling module FEA-based. Winding close to the gap.

• Modeling module FEA-based. Winding far from the gap.

It can be seen that the results obtained with PExprt analytical (no fringing flux consideration) are close to the ones obtained with the FEA-based model if the winding is far from the gap (no fringing flux influence).Since the gap is not very large in this design (0.5 mm), the impact on the losses is minimal while enabling you to quantify the gap effect without manufacturing iterations and measurements pro-cesses.


16Linking with SIMPLORER

The analytical-based and FEA-based models generated using PExprt and the Modeling module can be linked to different electrical simulators in order to simulate the behavior of the entire circuit.Ansoft SIMPLORER is one electrical simulator that can be used as part of an entire design pack-age. The combination of PExprt, the Modeling module, and SIMPLORER provides a unique, pow-erful way to design, model, and simulate electromagnetic systems.The goal for this chapter is to:• Use SIMPLORER to simulate the behavior of the entire circuit.

Note Refer to the SIMPLORER documentation to learn how to use the software in detail.


Linking with SIMPLORER 16-1


Defining the SIMPLORER Model LanguageIf you have not already done so in Chapter 11, “Constructive Results,” do the following to define the model language:1. Click Options>Preferences.

The Preferences window appears.2. Select the Modeling Language tab.

3. Click Simplorer to select it as the modeling language. 4. Click OK to apply the selection and close the window.

16-2 Linking with SIMPLORER


Generating the ModelTo generate the model:1. Click Modeler>Generate Model.

The Model Generation window appears.

2. Select Generate Analytical Model in order to generate the analytical model of the selected design.

3. Click OK to generate the model. If you have previously generated the model, a message appears, telling you whether you want to overwrite the previous model.

4. Click Yes to continue. A message appears, telling you that the 1D model has been successfully generated.

5. Click OK to close this message. A message appears, telling you the path to the 1D model netlist.

6. Click OK to close this message.You are now ready to open SIMPLORER and use the generated model as part of your circuit.



Using a PExprt Model in SIMPLORERTo use a PExprt model in SIMPLORER:1. Open the SIMPLORER application.2. Click the toolbar button to start the SIMPLORER Schematic.3. Click File>New on the SIMPLORER menu to create an empty schematic.4. Select the Add Ons tab in the ModelTree area.

5. Click the interface6 element.6. Drag the PExprt element from the ModelTree area, and drop it in the schematic area.



The PExprt element appears in the schematic area as shown below.

7. Double-click the PExprt element in the schematic area. The Properties window appears.

8. Click the Load Model button and use the browser to find the model netlist file (in the



BuckInductor_PEmagModels directory).

9. Click Open to load the model netlist file.10. Click OK to close the Properties window.

The symbol of the model is created in the schematic area.

Note If you want to show the pin names, double-click the model symbol and select Output/Display tab in order to define the visible pins.

Note To use the FEA-based model in SIMPLORER, selecting it instead of the analytical one.


17Planar Magnetic Component Designs

More designs are beginning to use planar magnetic components, and PExprt has been designed to work with planar designs using the same philosophy as wire components.The goal for this chapter is to:• Repeat the design of the buck inductor, this time using planar technology.


Planar Magnetic Component Designs 17-1


Setting Up the Planar DesignYou first need to change back to Design Mode to proceed with the design process.To set up the planar design:1. Click Calculations>Design Mode.

Since you previously generated the analytical model for the current project, a message appears asking if you want to remove that model.

2. Click Yes to remove the previously generated model.3. Click the Design Inputs tab in the Input/Output Data area of the PExprt working window.4. Select Planar Component as the Geometry.

5. To change the Spacing to reasonable values for a planar design, type 150 µm in the Intra-layer field and 200 µm in the Inter-layer field.

6. Increase the Maximum Parallel Turns value from 3 to 10.

17-2 Planar Magnetic Component Designs


To select appropriate core shapes for a planar design:1. Click the Cores tab in the Libraries area, and expand the Ferroxcube_Design library.

2. Right-click on the POT type, and select Unselect All from the shortcut menu. The POT label now appears in gray, indicating there are no cores selected for that type.

3. Right-click on the RM type, and select Unselect All from the shortcut menu. The RM label now appears in gray, indicating there are no cores selected for that type.

4. Right-click on the EI type, and select Select All from the shortcut menu. The EI label now appears in green, indicating there are cores selected for that type.

5. Click File>Save to save the project.



To start the design process for this planar component:1. Click Calculations>Start Design Process. The Auto-Select feature is applied for the planar

wires parameter. A message appears, asking if you want to allow PExprt to auto-select the wires.

2. Click Yes. The design process begins. When the design process has completed, a design report message appears, telling you how many valid designs have been obtained from the total number of designs analyzed. In this particular case, PExprt tells you it has obtained 469 valid results out of 889 analyzed designs. Since you specified Solution Selection on the Modeling Options tab, only the best 10 solutions, in terms of losses, are shown.

3. Click OK to close this window. The List of Results tab appears.

You can now explore the performance and constructive results, as explained in Chapter 10, “Performance Results,” and Chapter 11, “Constructive Results.”



For example, if you select the first design from the List of Results tab, and then click the Constructive Results tab, you obtain the cross-section of the planar inductor, as shown below:




18Toroidal Component Designs

PExprt has been designed to work with toroidal designs using the same philosophy as concentric components.The goal for this chapter is to:• Repeat the design of the buck inductor, this time using a toroidal core.


Toroidal Component Designs 18-1


Setting Up the Toroidal DesignTo remove current list of results:1. Select Calculations>Remove List of Results in order to remove the current list of results.

A message appears asking if you want to delete all designs in the current list of results.2. Click Yes.To set up a toroidal design:1. Click Design Inputs tab in the Input/Output Data area of the PExprt working window.2. Select Toroidal Component as the Geometry.

3. To change the Spacing to reasonable values for a toroidal design, select Spacing, and type 10 in both the Intra-layer and Inter-layer fields.

To select appropriate core materials for a toroidal component (no air gap):1. Click the Material tab in the Libraries area, and expand the Ferroxcube_Design library.

2. Right-click on the FERRITE type, and select Unselect All from the shortcut menu. The FERRITE label now appears in gray, indicating there is no core material selected.

18-2 Toroidal Component Designs


3. Expand the IRON POWDER library. Right-click on to select 2P40. A "tool" icon appears in front of each selected core, as shown below:

4. Click File>Save to save the project.

To start the design process for this toroidal component:1. Click Calculations>Start Design Process. The Auto-Select feature is applied for the toroidal

cores and the wires selection. Since the switching frequency (200 kHz) is out of the typical frequency range of the 2P40 material, a window appears, asking if you want to unselect this material.

2. Click No to continue. A window appears, asking if you want to auto-select the cores and wires.

3. Click Yes to have PExprt automatically select the cores and wires. The design process begins.

When the design process has completed, a design report message appears, telling you how many valid designs have been obtained from the total number of designs analyzed. In this particular case, PExprt tells you it has obtained 79 valid results out of 423 analyzed designs. Since you specified Solution Selection on the Modeling Options tab, only the best 10 solutions, in terms of losses, are shown.

Toroidal Component Designs 18-3


4. Click OK to close this window. The List of Results tab appears.

You can now explore the performance and constructive results, as explained in Chapter 10, “Performance Results,” and Chapter 11, “Constructive Results.”

For example, if you select the first design from the List of Results tab, and then click the Con-structive Results tab, you obtain the top view of the toroidal inductor, as shown below:

Note The meaning of the icons that appear in front of each design of the list of results is explained in Chapter 9.

18-4 Toroidal Component Designs

Index

Numerics1D analytical model 12-4

Aalias 2-4Analysis Mode 14-1analytical-based model 16-3Ansoft SIMPLORER 13-1, 16-1automatically select design elements 5-5Auto-Select feature 5-5

Bbobbin 7-3buck inverter

sample problem 1-4

Cclassifying the list of results 10-2component 11-3constructive results parameters 11-3Constructive Results tab 11-1Control Panel

about 2-2

buttons 2-2starting 2-2

creatingproject directory 2-4projects 2-1, 2-5

criteria for Auto-Select 5-5current density 10-8, 10-9

Ddefaults for Auto-Select 5-5defining modeling language 12-3Design Inputs tab 7-2, 7-3design library

role 5-2selecting 5-2selecting elements 5-3

Design Mode 14-1design parameters 7-3design process

starting 9-2designing magnetic components

general procedure 1-3designs

generating 9-1directory

alias 2-4project 2-4

Index-1


dragging stock library to design library 5-2

Eelectrical simulators 13-1, 16-1Elements Information area 3-5English units 3-10

Fflux density 10-9fringing gap energy 7-3

Ggap 7-3general procedure

PExprt 1-3generating designs 9-1geometry 7-3Graphical Information area 3-5grayed-out (text and buttons) 2-6

Iincremental permeability 10-9inductance 10-8Input/Output Data area 3-4

Constructive Results tab 11-1Design Inputs tab 7-2List of Results tab 9-4Modeling Options tab 8-2Performance Results tab 10-1Waveforms tab 6-2

introductionPExprt 1-1

invoking the Modeling module 15-2

Llibraries

stock 3-6Libraries area 3-5

limit values 7-5linking to PEmag (the Modeling module) 15-1linking to the Modeling module (PEmag) 15-1list of results settings 8-5List of Results tab 9-4losses 10-5

Mmargin tapes 7-5Maxwell SPICE 3-6metric units 3-10model

generating analytical model 16-3model language

defining SIMPLORER 13-2, 13-4, 13-6, 13-8, 16-2

modelinggenerating a 1D analytical model 12-4

modeling language 3-6defining 12-3

Modeling moduleusing models in PExprt 15-5

Modeling module (PEmag) 15-1Modeling Options tab 8-2, 8-3modeling parameters 8-3modes in PExprt 14-1

Nnew project 2-5

Oobjects

drawing 3-1opening projects 3-2optimizing number of turns for minimum losses 8-4Options/Preferences 3-6

Pparameters

Index-2


constructive results 11-3performance results 10-5

PEmaginvoking the Modeling module 15-2

PEmag (the Modeling module) 15-1performance results parameters 10-5Performance Results tab 10-1permeability 7-3, 10-9PExprt

general procedure for designing magnetic compo-nents 1-3

results to expect 1-5sample problem, buck inverter 1-4starting 3-2

PExprt working window 3-4planar magnetic components 17-1Post Processor

starting 7-6, 15-8, 17-5, 18-4Power Electronics Expert (PExprt)

introduction 1-1preferences 3-6

modeling language 3-6stock library settings 3-6units 3-10

projectadd 2-4creating 2-1, 2-5directory 2-4new 2-5notes 2-6opening 3-2

Project Managerstarting 2-3window 2-2

PSpice 3-6

Rresults 9-1results to expect 1-5results, viewing 7-6, 15-8, 17-5, 18-4role of design library 5-2

Ssample problem

buck inverter 1-4selecting a design library 5-2selecting elements from the design library 8-5selecting library elements 5-3SIMPLORER 3-6, 12-3, 13-1, 16-1

using a PExprt model 16-4solution results 9-1solutions, generating 5-1specifications for sample problem 1-4starting

Control Panel 2-2PExprt 3-2Post Processor 7-6, 15-8, 17-5, 18-4Project Manager 2-3

starting the design process 9-2stock libraries 3-6

Ttemperature rise 10-9toroidal component designs 18-1

Uunits of measurement 3-10using models from the Modeling module in PExprt 15-

5

Vventilation type 7-4viewing

results 7-6, 15-8, 17-5, 18-4

WWaveforms tab 6-2winding DC losses 10-7winding efficiency 7-5winding losses calculation 8-3

Index-3


winding setup 7-4window

Project Manager 2-2window occupancy 10-8working window 3-4

Index-4

Date post:	02-Oct-2021
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Getting Started: An Inductor Design Example

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