Development Facility More Electric Aircraft Power System ...

MEA Power System Development Facility

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More Electric Aircraft Power System Development Facility Introduction Over the past decade, the aircraft industry has converged on a shared vision for the future of aircraft

power systems. This vision represents a dramatic shift away from various types of power found in

traditional aircraft and offers a wide range of benefits for tomorrow’s commercial and military aircraft.

The non-propulsive power systems in traditional aircraft are typically driven by a combination of

different secondary power types including: hydraulic, pneumatic, electrical and mechanical power [1-6].

All power is extracted from the aircraft engines. Hydraulic power is provided using hydraulic pumps

driven by mechanical rotation sourced from the engine gearbox and is distributed to power various

aircraft systems including flight control actuators, aircraft braking, landing gear extension/retraction,

and door closure. Pneumatic power is extracted from the engine, using software controlled bleed

valves, and is used to power the aircraft Environmental Control System (ECS) and wing anti-icing.

Mechanical power from the engine gearbox also drives lubrication and fuel pumps. While electrical

power contributes to the capability of nearly every aircraft system in modern aircraft that make

increasing use of airborne software controlled electronic systems.

The market demand for more energy efficient aircraft is driven by many stakeholders including airline

operators, legislators, and public opinion. In the meantime, power electronics technology has made

tremendous breakthroughs over the past decade in areas including electromechanical actuators (EMA),

electro-hydrostatic actuators (EHA), fault-tolerant electric motor/generators, and power converters.

This forward-leap of technology creates a viable path, fueled by economic gain, for replacing many and

potentially all of the hydraulic, pneumatic, a mechanically powered non-propulsive systems with

electrically powered systems [1-25] to design a More Electric Aircraft (MEA).

The Challenge Industry has recently achieved general agreement on key elements of the MEA. For example, industry is

now focusing on technology based on a high-voltage DC power distribution architectures with 270VDC

distribution emerging as the most popular approach. However, optimizing aircraft power systems

technology to support a 270VDC distribution system, including generation, distribution topology, power

conversion, and the design of specific MEA systems, is a complex effort. There is a high-level of

dependency and interaction between the various systems in a given MEA design with complex and fast

dynamics. There is a wide range of technology that must be refined and optimized within the context of

a single aircraft design in order to achieve the cost reduction goals for the MEA. These challenges give

rise to a capability requirement; a requirement for a flexible MEA development platform that can

accelerate the pace of development of MEA technology.

The Solution The proposed solution relies on Model Based Systems Engineering (MBSE) methodologies and

technology that have evolved rapidly over the past two decades and draws on MBSE technology in the

area of power systems and power electronics. This whitepaper proposes a Power-Hardware-in-the-Loop



development and test facility that enables MEA technology to be combined with simulated flight and

simulated power system behavior: The MEA Power System Development Facility. The MEA Power

System Development Facility enables technology concepts and prototypes to be tested as pure

simulation in closed-loop with real aircraft power systems, operating with representative electrical

behavior, and evaluated through normal and failure mode flight conditions. The MEA Power System

Development facility is based on Applied Dynamics technology development and contribution to the

current state-of-the-art in the aircraft industry’s drive towards the MEA vision.

More Electric Aircraft Power Systems Development Facility The More Electric Aircraft Power Systems (MEAPS) Development Facility is a high-performance, real-

time, power-hardware-in-the-loop developing and testing capability that: allows high-fidelity aircraft

simulation to be combined with real and/or simulated aircraft power system devices; enables the



configuration of the MEA power network to be changed and evaluated; allows real and emulated

generators to be connected to the MEA power network; provides high-fidelity active load emulation to

evaluate the effects and performance of electromechanical and electrohydrostatic actuators; and

includes high-speed data acquisition throughout the facility for the characterization of each element of

the system. Components of the MEAPS Development Facility include:

Active load emulation system

Active load Hyperfast real-time simulator

Generator emulation system

Distributed real-time simulator platform

MEA power network

Flight and aircraft system simulation models

Simulation framework software platform

Active Load Emulation System The active load emulation system is a power hardware system that provides bidirectional energy

transfer for DC sources or loads. The active load system generates a dynamic DC load and feed the

resulting power back into the facilities 3-phase AC. The DC voltage is controlled by a setpoint input for

each output channel. The figure below shows a schematic of a 3-channel active load emulation system.

The active load emulation system is used in the MEAPS Development Facility to draw DC current off the

HVDC MEA power network with behavior controlled by simulation of dynamics loads. For example, the



active load Hyperfast real-time simulator is used to run high-fidelity electromechanical or

electrohydrostatic simulation models, the value of this current draw is sent from the Hyperfast real-time

simulator to the active load system which behaves accordingly. The figure below shows the dynamics

DC current behavior generated by the active load emulation system when a flight control position step

change command is sent to an electromechanical flight control actuator simulation and drive the active

load system.

Active Load Hyperfast Real-Time Simulator The active load Hyperfast real-time simulator is a real-time simulation computer system dedicated to

providing control of the active load emulation system. This real-time system is a multi-core,

deterministic simulator capable of running simulation with sub-10us step time. Simulation models (ex:

Simulink, C code, etc.) are locked to a processor core with direct access to analog and/or digital interface

channels. This real-time simulator uses the ADvantage Framework software for system configuration,

operation, and data acquisition. The active load real-time simulator interfaces with the other real-time

simulation computers in the MEAPS Development Facility using the ADvNET distributed real-time

simulation toolbox.



The figure above illustrates an electromechanical actuator simulation that is executed on the active load

Hyperfast real-time simulator. The position controller, speed controller, current controller, motor, and

gearbox/ballscrew are modelled. The figure below shows this nested closed-loop control simulation

implemented in Simulink. The value of DC current, Iload, becomes the setpoint to the active load

emulation system.

The MEAPS Development Facility allows multiple EMA and EHA actuators to be simulated and allows

their electrical behavior and interaction with the MEA power network to be replicated in real-time. This

allow all the actuators for a single aircraft to be simulated and electrically emulated.

The position and load command sent to the active load Hyperfast real-time simulator is generated by

the real-time flight simulation (ex: 6DOF, aerodynamics, flight control system, etc.) executed in the

distributed real-time simulation platform. This enables the MEA power network, and all real power

systems included in a test to interact with power system dynamics that are highly representative of any

desired flight conditions.

Generator Emulation System The generator emulation system is a power module that provides bidirectional transfer of energy

between AC source and DC loads. In the case of the MEAPS Development Facility, the MEA power

network acts as the DC load and the generator emulation system acts as a DC voltage generator with

programmable, dynamics voltage setpoint and programmable current limit. The generator emulation

system provides behavior that matches a real engine driven generator with AC-DC converter behavior by

executing real-time simulation models of the gas turbine engine, the generator, the converter, and the

generator/converter control unit. These simulation models are executed on the distributed real-time

simulator platform send voltage setpoints to the generator emulation system, and receive voltage and

current measurement feedback from the generator link to the aircraft power network. This real-time

simulation results in converter output voltage and current characteristics that are sent to the generator

emulation system and performed. The figure below shows a schematic of the generator emulation

power module.





Distributed real-time simulator platform The real-time simulator platform provides the ability to execute high fidelity flight simulation, simulation

of aircraft systems, and simulation of power system dynamics with real aircraft systems in-the-loop.

This enables the MEAPS Development Facility to incorporate real electrical loads, connected to the MEA

power network, stimulated to behave as they do during flight. The MEAPS Development Facility uses a

distributed real-time simulation system with multiple simulator nodes, each with multicore processors.

The figure above illustrates the distributed real-time simulator platform. The multiple simulator nodes

communicate with one another across a high-speed distributed communication interface. The

ADvantage Framework software platform allows these systems to be configured and operated as though

they were a single simulation system. A distributed, IRIG-B common clock triggers the time scheduling

of each system and maintain synchronized execution of simulation and I/O scheduling.

Signal interfaces included in the distributed real-time simulator platform put each aircraft system under-

test into closed-loop operation with simulation models and/or other aircraft systems providing realistic

and accurate behavior. The real-time simulator platform interface signals can be divided into four main

types. The table below lists these interface signal types.



Signal Type Example

Sensor Emulation Thermocouple, Resistive Temperature Device, Linear Variable Displacement Transducer (LVDT), Digital Encoder, etc.

Actuator Measurement Torque Motor, Solenoid, Igniter, etc.

Serial and Databus ARINC-664, ARINC-429, CAN, RS232/422/485, MIL-STD-1553, IEEE1394, etc.

Data Acquisition Channels Analog, Digital

MEA power network The MEA power network is a ‘ring main’ type distribution system offering flexibility for isolating loads,

for re-routing power during faults at various locations throughout the network, and providing the ability

to share power between generating sources. Protective functionality is provided with switchgear that

also provides the ability to insert electrical faults. Fault management, ring configuration and re-routing,

and load management are controlled using a real-time controller.

Load Emulation Three types of load emulation may be included in the MEAPS Development Facility to represent

different aircraft system load characteristics. These include:

Resistive loads – This provides a constant load on the DC network in order to replicate

“background” loads found in the aircraft such as avionics systems. A variable resistive load

allows the load level to be increased in steps up to 50kW.

Continuous switching power electronic load – This represents a power electronics interface to

drive a number of continuously running loads, such as the aircraft environmental control

system, electric fuel pump, and radar communications system. This type of load emulation is

provided by the active load emulation system described earlier in this paper.

Dynamics switching power electronic load – This represents the “pulse” loads associated with

electromechanically actuated flight controls. This type of load emulation is provided by the

active load emulation system described earlier in this paper.

Flight and Aircraft System Simulation Models Applied Dynamics offers the iAircraft Simulink aircraft model library providing real-time simulation of

flight and aircraft systems. iAircraft is a comprehensive set of aircraft simulation capability used in the

aircraft industry for a wide range of applications. The iAircraft library is an open architecture set of

models enabling users to parameterize, reconfigure, and replace Simulink subsystems as needed. The

iAircraft library includes the following:

High fidelity 6-degree-of-freedom flight dynamics model with rotating spherical earth &

configurable aerodynamics

Configurable landing gear with nose wheel steering as a function of rudder pedal and tiller

travel, high-fidelity tire model, and dynamics gear suspension

Comprehensive autopilot modules including intercept & track, heading hold, bank angle hold,

and more

Aircraft ‘trim’ module for initializing flight at a selected stable flight condition



Scriptable ILS landing capability

High fidelity gas turbine engine model for testing application that include an EEC or low fidelity

model engine pressure ration based model for simpler development and testing applications

High fidelity Environmental Control System (ECS) blockset

Out-The-Window (OTW) visuals interface

The figure below shows the iAircraft library within the Simulink browser.

The iAircraft flight controls library components can be used to simulation hydraulic, electromechanical,

or electrohydrostatic flight control actuators and can be put in closed-loop with the dynamics load

system.

The iAircraft landing gear library components include high-fidelity runway interaction with high-fidelity

lateral and longitudinal tire model for steering and antiskid braking. The landing gear model provides

the fidelity and detail required to drive the dynamic load system with antiskid braking power behavior.

The figure below shows an example iAircraft braking and steering configuration.



Power System Simulation Aircraft power system simulation models are required to provide accurate dynamics behavior of all

emulated power system components. These power system models include:

Generator and generator control unit models – switch level model including exciter, rotating

rectifier, and diode bridge/inverter output stage

Electrical distribution unit model – feeder electrical dynamics between the generator inverter

converter controller (ICC), the actuator loads, and generic loads

DC-DC converter models – RMS current models and average current models for boost and buck

mode converter operation

EMA and EHA actuator models – segment level actuator models including input EMI filters,

active switching, and rotating machine

All aircraft power system simulation models are developed in Simulink using the SimPowerSystems

toolbox. The accuracy and detail of component blocks within SimPowerSystems are ideally suited for

modeling complex electrical behavior. However, the real-time performance of these models can be

problematic in terms of the computational efficiency of the generated code and the ability to execute

these models at a frequency sufficient to represent fast dynamics. Applied Dynamics has been

successful in solving this problem by systematically replacing some of the inefficient generated code

with highly optimized code[40]. The figure below shows a Simulink SimPowerSystems model of the MAE

electrical distribution unit.



Simulation framework software platform Software to rapidly configure and operate the MEAPS Development Facility is provided using the

ADvantage Framework MBSE software platform. ADvantage provides real-time simulation and analysis

capability for advanced aircraft development projects throughout the world and at leading aerospace

and defense companies including: Boeing, Gulfstream, Rolls-Royce, Crane Aerospace, Parker Aerospace,

COMAC, BAE Systems, Mitsubishi Heavy Industries, and General Dynamics.

ADvantage includes desktop tools and run-time services software. Tools include:

ADvantageDE – Development environment used to configure the MEAPS facility, add Simulink

models, connect real and simulated equipment, compile and package projects

ADvantageVI – Operator environment used to control the facility through interactive or

automated tests

SIMplotter – Data acquisition, plotting and analysis of distributed real-time streaming data

ADvantageDB – Configuration of analysis of serial and databus networks

ADvantageFC – Electrical fault insertion macro definition and control



The ADvantage run-time services software provides the high-performance software capabilities within

each real-time simulator in the MEAPS facility including: logical device engine, serial communications

handler, assembly containers probe engine, data acquisition engine, real-time scripting engine,

supervisory schedule, and Ethernet connected control adapter.

Generator-in-the-Loop In addition to generator emulation, the MEAPS Development Facility also allows real generators to be

put in-the-loop for the development of generator control units, to evaluate performance, fault

tolerance, etc. The figure below shows a real generator incorporated into the MEAPS Development

Facility.

In order to add a real generator to the facility, a dynamometer is used to provide mechanical drive that

is controlled in closed-loop with the gas turbine engine simulation. A control loop is incorporated within

the real-time simulator to set speed commands to the dynamometer AC drive, measure shaft load, and

turn the real generator with behavior matching the generator operating during simulated flight.



Testing Aircraft Electrical Network Protection HVDC aircraft power networks represent significant challenges for electrical network protection. The

high levels of stored energy and low impedance interconnections between systems can lead to the

creation of high peak fault current magnitudes and rapidly propagating fault effects. Therefore, very

fast acting protection schemes must be developed to

achieve the desired levels of protection to minimize

disruption to the remainder of the electrical network.

Furthermore, the electronic converters required by this

type of HVDC network worsen the protection challenge.

The MEAPS facility is the ideal development and test

platform for developing protection strategies and testing

prototype fault protection equipment. Significant work is

on-going across the industry to develop fast acting solid-

state circuit breakers such as the Emitter Turn Off (ETO)

based DC circuit breaker shown below.

Test and Evaluation of Advanced Power Electronics A critical component of the MEA HVDC architecture is high-efficiency DC-DC converter used to convert

from 270VDC distributed power to low voltage

power used by aircraft systems. Significant

innovation is happening across the industry for

a range of MAE power electronics technologies.

The figure below shows an advanced Dual

Active Bridge (DAB) DC-DC converter designed

for MEA applications and tested at the IEPNEF

facility in the UK.



References [1] I. Moir and A. Seabridge, “Aircraft systems : mechanical, electrical, and avionics subsystems

integration”. London, 2001.

[2] M. J. J. Cronin, "The all-electric aircraft," IEE Review, Vol. 36,1990, pp. 309-311.

[3] R. I. Jones, "The More Electric Aircraft: the past and the future?," in IEE Colloquium on Electrical

Machines and Systems for the More Electric Aircraft, , 1999, pp. 1/1-1/4.

[4] R. E. J. Quigley, "More Electric Aircraft," Proceedings of 8th the Applied Power Electronics Conference

and Exposition, APEC '93., 1993, pp. 906-911.

[5] I. Moir, "More-electric aircraft-system considerations," IEE Colloquium on Electrical Machines and

Systems for the More Electric Aircraft , 1999, pp. 10/1-10/9.

[6] I. Moir, "The all-electric aircraft-major challenges" IEE Colloquium on All Electric Aircraft, , 1998, pp.

2/1-2/6.

[7] M. Howse, "All electric aircraft," Power Engineer Vol. 17, 2003, pp. 35-37.

[8] J. A. Rosero, J. A. Ortega, E. Aldabas, and L. Romeral, "Moving towards a more electric aircraft," IEEE

Aerospace and Electronic Systems Magazine, Vol. 22, 2007, pp. 3-9.

[9] S. J. Cutts, "A collaborative approach to the More Electric Aircraft," The processing of International

Conference on Power Electronics, Machines and Drives, PEMD 2002., 2002, pp. 223-228.

[10] J. A. Weimer, "Electrical power technology for the more electric aircraft," The processing of 12th

AIAA/IEEE Digital Avionics Systems Conference, DASC 1993., 1993, pp. 445-450.

[11] M. A. Maldonado and G. J. Korba, "Power management and distribution system for a more-electric

aircraft (MADMEL)," IEEE Aerospace and Electronic Systems Magazine, Vol. 14, pp. 3-8, 1999.

[12] M. A. Maldonado, N. M. Shah, K. J. Cleek, P. S. Walia, and G. J. Korba, "Power Management and

Distribution System for a More-Electric Aircraft (MADMEL)- program status," Proceedings of the 32nd

Intersociety Energy Conversion Engineering Conference, IECEC-97., 1997, pp. 274-279 Vol.1.

[13] M. A. Maldonado, N. M. Shah, K. J. Cleek, P. S. Walia, and G. Korba, "Power management and

distribution system for a more-electric aircraft (MADMEL)-program status," Proceedings of the 31st

Intersociety, Energy Conversion Engineering Conference, IECEC 96. 1996, pp. 148-153 Vol.1.

[14] W. Pearson, "The more electric/all electric aircraft-a military fast jet perspective," IEE Colloquium

on All Electric Aircraft 1998, pp. 5/1-5/7.

[15] L. Andrade and C. Tenning, "Design of Boeing 777 electric system," IEEE Aerospace and Electronic

Systems Magazine, Vol. 7, pp. 4-11, 1992.

[16] A. Ponton and e. al, "Rolls-Royce Market Outlook 1998-2017," Rolls-Royce Publication No TS22388.

[17] K. Emadi and M. Ehsani, "Aircraft power systems: technology, state of the art, and future trends,"

Aerospace and Electronic Systems Magazine, IEEE, Vol. 15, pp. 28-32, 2000.



[18] J. S. Cloyd, "A status of the United States Air Force's More Electric Aircraft initiative," Proceedings of

the 32nd Intersociety Energy Conversion Engineering Conference, IECEC-97., 1997, pp. 681-686 Vol.1.

[19] K. C. Reinhardt and M. A. Marciniak, "Wide-band gap power electronics for the More Electric

Aircraft," Proceedings of the 31st Intersociety Energy Conversion Engineering Conference, IECEC 96.,

1996, pp. 127 - 132.

[20] L. J. Feiner, "Power electronics transforms aircraft systems," Proceedings of the WESCON/94.

'Idea/Microelectronics'. Conference 1994, pp. 166-171.

[21] T. F. Glennon, "Fault-tolerant generating and distribution system architecture," IEE Colloquium on

All Electric Aircraft, 1998, pp. 4/1-4/4.

[22] T. L. Ho, R. A. Bayles, and E. R. Sieger, "Aircraft VSCF generator expert system,"IEEE Aerospace and

Electronic Systems Magazine, Vol. 3, pp. 6-13, 1988.

[23] A. C. Hoffman, I. G. Hansen, R. F. Beach, R. M. Plencner, R. P. Dengler, K. S. Jefferies, and R. J. Frye,

"Advanced secondary power system for transport aircraft," 1985.

[24] G. M. Raimondi, T. Sawata, M. Holme, A. Barton, G. White, J. Coles, P. H. Mellor, and N. Sidell,

"Aircraft embedded generation systems," Proceedings of the International Conference on Power

Electronics, Machines and Drives, 2002, PEMD 2002., pp. 217-222.

[25] C. Cossar and T. Sawata, "Microprocessor controlled DC power supply for the generator control unit

of a future aircraft generator with a wide operating speed range," Proceedings of the International

Conference on Power Electronics, Machines and Drives, 2004, PEMD 2004, Vol.2 pp. 458-463.

[26] S. Ying Shing and C. E. Lin, "A prototype induction generator VSCF system for aircraft," Proceedings

of the International IEEE/IAS Conference on Industrial Automation and Control: Emerging Technologies,

1995, pp. 148-155.

[27] R. C. Bansal, "Three-phase self-excited induction generators: an overview," IEEE Transaction on

Energy Conversion, 2005. Vol. 20, pp. 292-299.

[28] R. C. Bansal, T. S. Bhatti, and D. P. Kothari, "Bibliography on the application of induction generators

in nonconventional energy systems," IEEE Transaction on Energy Conversion, 2003. Vol. 18, pp. 433-439.

[29] F. Khatounian, E. Monmasson, F. Berthereau, E. Delaleau, and J. P. Louis, "Control of a doubly fed

induction generator for aircraft application," Proceedings of the 29th Annual IEEE Conference on Industrial

Electronics Society, 2003. IECON '03. 2003, Vol.3 pp. 2711-2716.

[30] M. E. Elbuluk and M. D. Kankam, "Potential starter/generator technologies for future aerospace

applications," IEEE Aerospace and Electronic Systems Magazine, Vol. 12, pp. 24-31, 1997.

[31] T. L. Skvarenina, O. Wasynczuk, P. C. Krause, C. Won Zon, R. J. Thibodeaux, and J. Weimer,

"Simulation and analysis of a switched reluctance generator/More Electric Aircraft power system,"

Proceedings of the 31st Intersociety Energy Conversion Engineering Conference, 1996. IECEC 96. Vol. 1.

pp. 143-147.

[32] E. Richter and C. Ferreira, "Performance evaluation of a 250 kW switched reluctance starter

generator," Proceedings of the 13th IEEE Industry Applications Conference, 1995. Vol. 1. pp. 434-440.



[33] Cross, A.M. et al., "Electrical System Evaluation Platform for Uninhabited Autonomous Vehicles",

SAE Power Systems Conference. Nov. 2006, New Orleans US.

[34] Powell, D. et al., "An Integrated Starter-Generator for a Large Civil Aero-Engine", AIAA 2005-5550.

[35] Pimentel, J., Tirat-Gefen, Y, "Real-Time Hardware in the Loop Simulation of Aerospace Power

Systems", AIAA 2007-4716.

[36] Stranjak, P. et al., "Agent-based Control of Autonomous Power Management on Unmanned

Platforms", 4th SEAS DTC Technical Conference, Edinburgh 2009.

[37] Fletcher, S. et al., "Impact of Converter Interface Type on the Protection Requirements for DC

Aircraft Power Systems", AIAA 2007-4716.

[38] Fletcher, S. et al., "Modeling and Simulation Enabled UAV Electrical Power System Design", SAE

2001-01-2645.

[39] Naayagi, R.T., Forsyth, A., "High-Power Bidirectional DC-DC Converter for Aerospace Applications",

IEEE Transactions on Power Electronics, Vol. 27, No. 11, Nov. 2012.

[40] Roscoe, A.J., Blair, S.M., Burt, G.M., “Benchmarking and optimization of Simulink code using Real-

Time Workshop and Embedded Coder for inverter and microgrid control applications”. Proc. Univ.

Power Eng. Conf. (UPEC), 2009.

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