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© Copyright Ned Mohan 2008 1
First Course onPower ElectronicsModule 1: Introduction
Reference Textbook:First Course on Power Electronics by Ned Mohan, www.mnpere.com
ByNed Mohan
Professor of ECEUniversity of Minnesota
© Copyright Ned Mohan 2008 2
Chapter 1 Power Electronics: An Enabling Technology
1-1 Introduction to Power Electronics 1-2 Applications and the Role of Power Electronics 1-3 Energy and the Environment 1-4 Need for High Efficiency and High Power Density 1-5 Structure of Power Electronics Interface 1-6 Voltage-Link Structure 1-7 Recent and Potential Advancements
References Problems
Module 1: Introduction to Power Electronics
© Copyright Ned Mohan 2008 3
Role of Power Electronics
Figure 1-1 Power electronics interface between the source and the load.
Converter
Controller
Source Load
Power ElectronicsInterface
Converter
Controller
Source Load
Power ElectronicsInterface
The power electronics interface facilitates the transfer of power from the source to the load by converting voltages and currents from one form to another, in which it is possible for the source and load to reverse roles. The controller shown in Fig. 1-1 allows management of the power transfer process in which the conversion of voltages and currents should be achieved with as high energy-efficiency and high power density as possible.
© Copyright Ned Mohan 2008 4
Powering the Information Technology
Figure 1-2 Regulated low-voltage dc power supplies.
Power Converter
Controller
oV
,o refV
inV Utility
24 V (dc) 5 V (dc)
3.3 V (dc)
0.5 V (dc)
(a) (b)
Power Converter
Controller
oV
,o refV
inV Power Converter
Controller
oV
,o refV
inV Utility
24 V (dc) 5 V (dc)
3.3 V (dc)
0.5 V (dc)
Utility
24 V (dc) 5 V (dc)
3.3 V (dc)
0.5 V (dc)
(a) (b)
© Copyright Ned Mohan 2008 5
Boost Converter
Figure 1-3 Boost dc-dc converter needed in cell operated equipment.
BatteryCell (1.5 V) 9 V (dc)BatteryCell (1.5 V) 9 V (dc)
© Copyright Ned Mohan 2008 6
Adjustable Speed Drives
Figure 1-4 Block diagram of adjustable speed drives.
Power Processing Unit (PPU)fixed
form
measured speed/ position
speed /position
Motor
Electric Drive
Load
input command (speed / position)
PowerSignal
adjustable form
Electric Source(utility)
Sensors
Controller
© Copyright Ned Mohan 2008 7
Induction Heating
Figure 1-5 Power electronics interface required for induction heating.
HighFrequencyAC
PowerElectronicsInterface
Utility
HighFrequencyAC
PowerElectronicsInterface
Utility
© Copyright Ned Mohan 2008 8
Electric Welding
Figure 1-6 Power electronics interface required for electric welding.
DCPowerElectronicsInterface
Utility
DCPowerElectronicsInterface
Utility
© Copyright Ned Mohan 2008 9
Energy and the Environment: The Percentage Energy Consumption
Figure 1-7 Percentage use of electricity in various sectors in the U.S.
Motors 51%HVAC 16%
IT 14%
Lighting 19%
Motors 51%HVAC 16%
IT 14%
Lighting 19%
Motors 51%HVAC 16%
IT 14%
Lighting 19%
© Copyright Ned Mohan 2008 10
Figure 1-8 Role of adjustable speed drives in pump-driven systems.
AdjustableSpeed Drive
(ASD)Inlet
Outlet
Pumputility
AdjustableSpeed Drive
(ASD)Inlet
Outlet
Pumputility
Role of adjustable speed drives in pump-driven systems
© Copyright Ned Mohan 2008 11
Compact Fluorescent Lamps
Figure 1-9 Power electronics interface required for CFL.
CFLPowerElectronicsInterface
Utility
CFLPowerElectronicsInterface
Utility
© Copyright Ned Mohan 2008 12
• Hybrid electric vehicles with much higher gas mileage
• light rail, fly-by-wire planes
• all-electric ships
• drive-by-wire automobiles.
Transportation
Figure 1-10 Hybrid electric vehicles with much higher gas mileage.
© Copyright Ned Mohan 2008 13
Renewable EnergyPhotovoltaic Systems
Figure 1-11 Photovoltaic Systems. (a)
PowerElectronicsInterface
Utility
DC Input
(b)
(a)
PowerElectronicsInterface
Utility
DC Input
(b)
PowerElectronicsInterface
Utility
DC Input PowerElectronicsInterface
Utility
DC Input
(b)
© Copyright Ned Mohan 2008 14
Wind-Electric Systems
Figure 1-12 Wind-electric systems.
Utility
GeneratorandPower Electronics
Utility
GeneratorandPower Electronics
Utility
GeneratorandPower Electronics
© Copyright Ned Mohan 2008 15
Uninterruptible Power Supplies
Figure 1-13 Uninterruptible power supply (UPS) system.
Utility CriticalLoad
UninterruptiblePower Supply
Utility CriticalLoad
UninterruptiblePower Supply
© Copyright Ned Mohan 2008 16
Applications in Power Systems
© Copyright Ned Mohan 2008 17
Strategic Space and Defense Applications
Electric WarshipMore Electric Aircraft
Source: James Soeder, NASA and Terry Ericsen, ONR.
© Copyright Ned Mohan 2008 18
NEED FOR HIGH EFFICIENCY AND HIGH POWER DENSITY
o
o loss
PP P
η =+ 1o lossP Pη
η=
−
Figure 1-14 Power output capability as a function of efficiency.
inP oP
lossP( )a
Power ElectronicsEquipment
0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.960
50
100
150
200
250
300
350
400
450
500
Efficiency
Pow
er R
atin
g
( )b
oP20lossP W=
10lossP W=
η
inP oP
lossP( )a
Power ElectronicsEquipment
0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.960
50
100
150
200
250
300
350
400
450
500
Efficiency
Pow
er R
atin
g
( )b
oP20lossP W=
10lossP W=
η
© Copyright Ned Mohan 2008 19
Summarizing the Role of Power Electronics
Output to Load- Adjustable DC- Sinusoidal AC- High-frequency AC
utility
PowerElectronicsInterface
Output to Load- Adjustable DC- Sinusoidal AC- High-frequency AC
utility
PowerElectronicsInterface
Figure 1-15 Block diagram of power electronic interface.
Output to Load- Adjustable DC- Sinusoidal AC- High-frequency AC
utility
PowerElectronicsInterface
Output to Load- Adjustable DC- Sinusoidal AC- High-frequency AC
utility
PowerElectronicsInterface
Figure 1-15 Block diagram of power electronic interface.
© Copyright Ned Mohan 2008 20
STRUCTURE OF POWER ELECTRONICS INTERFACE
Voltage-link structure of power electronics interface• Unipolar voltage handling transistors used
• Decoupling of two converters
• Immunity from momentary power interruptions
Figure 1-16 Voltage-link structure of power electronics interface.
conv1 conv2
controller
utility Load
conv1 conv2
controller
utility Load
© Copyright Ned Mohan 2008 21
• Current-Link Systems
• Matrix Converters
© Copyright Ned Mohan 2008 22
Figure 1-17 Current-link structure of power electronics interface.
AC1 AC2AC1 AC2AC1 AC2AC1 AC2
Current-Link Systems
© Copyright Ned Mohan 2008 23
Figure 1-18 Matrix converter structure of power electronics interface [13].
vCvBvA
vc
vb
va
ia
daA
dbA
dcA
daB daC
dbB dbC
dcB dcC
vCvBvA
vc
vb
va
ia
daA
dbA
dcA
daB daC
dbB dbC
dcB dcC
Matrix Converters
© Copyright Ned Mohan 2008 24
Figure 1-19 Load-side converter in a voltage-source structure.
conv1 conv2
controller
utility Load
conv1 conv2
controller
utility Load
Voltage-link System
© Copyright Ned Mohan 2008 25
SWITCH-MODE LOAD-SIDE CONVERTER
• Group 1 Adjustable dc or a low-frequency sinusoidal ac output in - dc and ac motor drives - uninterruptible power supplies - regulated dc power supplies without electrical isolation
• Group 2 High-frequency ac in - compact fluorescent lamps - induction heating - regulated dc power supplies where the dc output voltage needs to be
electrically isolated from the input, and the load-side converter internally produces high-frequency ac, which is passed through ahigh-frequency transformer and then rectified into dc.
© Copyright Ned Mohan 2008 26
Switch-Mode Conversion: Switching Power-Pole as the Building Block
Figure 1-20 Switching power-pole as the building block in converters.
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
(b)
Av
0t
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
inV
+
-
(a)
+
-Av
Aq
inVAv
0
1Aq =
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
(b)
Av
0t
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
inV
+
-
(a)
+
-Av
Aq
inVAv
0
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
(b)
Av
0t
(b)
Av
0t
inV
+
-
(a)
+
-Av
Aq
inV
+
-
(a)
+
-Av
Aq
inVAv
0
1Aq =
© Copyright Ned Mohan 2008 27
Pulse-Width Modulation (PWM) of the Switching Power-Pole
upA in A in
s
Tv V d V
T= = 0 1Ad≤ ≤
( / )A up sd T T=
Figure 1-21 PWM of the switching power-pole.
(a) (b)
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
(a) (b)
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
Ad
(a) (b)
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
(a) (b)
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
AvinV
+
-
+
-
Ai
1or 0Aq =
A sd T
dAi
upTsT
Aq
Av
0
0t
t
1
inV
Av
Ad
© Copyright Ned Mohan 2008 28
Switching Power-Pole in a Buck DC-DC Converter: An Example
o A A inV v d V= = 0 o inV V≤ ≤
Figure 1-22 Switching power-pole in a Buck converter.
inV
+
−
Aq
+
−Av
+
−
oV
ini
Li
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
(a)
(b)
inV
+
−
Aq
+
−Av
+
−
oV
ini
Li
inV
+
−
Aq
+
−Av
+
−
oV
ini
Li
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
(a)
(b)
AvinV
+
−
Aq
+
−Av
+
−
oV
ini
Li
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
(a)
(b)
inV
+
−
Aq
+
−Av
+
−
oV
ini
Li
inV
+
−
Aq
+
−Av
+
−
oV
ini
Li
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
A sd T
sT
Aq
Av
Li
ini
0
0
0
0 t
inV
t
t
t
1
(a)
(b)
Av
© Copyright Ned Mohan 2008 29
Figure 1-23 Waveforms in the converter of Example 1-2.
Aq
Av
20inV V=
12oV V=
0
1
3 sμ5 sμ
t
t0
Aq
Av
20inV V=
12oV V=
0
1
3 sμ5 sμ
t
t
Aq
Av
20inV V=
12oV V=
0
1
3 sμ5 sμ
t
t0
Example 1-2 In the converter of Fig. 1-22a, the input voltage 20inV V= . The
output voltage 12oV V= . Calculate the duty-ratio Ad and the pulse
width upT , if the switching frequency 200sf kHz= .
Solution 12A ov V V= = . Using Eq. 1-4,12 0.620
oA
in
VdV
= = = and 1 5s
s
T sf
μ= = .
Therefore, as shown in Fig. 1-23, 0.6 5 3up A sT d T s sμ μ= = × = .
© Copyright Ned Mohan 2008 30
Simulations using PSpice
SwitchingWaveform.Sch
© Copyright Ned Mohan 2008 31
Simulation Results
Time
450us 460us 470us 480us 490us 500usV(vA) V(vo)
0V
2.0V
4.0V
6.0V
8.0VAv
o ov V
© Copyright Ned Mohan 2008 32
Fourier AnalysisFOURIER COMPONENTS OF TRANSIENT RESPONSE V(vA) DC COMPONENT = 6.080000E+00 HARMONIC FREQUENCY FOURIER NORMALIZED PHASE NORMALIZED NO (HZ) COMPONENT COMPONENT (DEG) PHASE (DEG) 1 1.000E+05 3.487E+00 1.000E+00 -4.860E+01 0.000E+00 2 2.000E+05 2.543E+00 7.293E-01 -7.200E+00 9.000E+01 3 3.000E+05 1.310E+00 3.757E-01 3.420E+01 1.800E+02 4 4.000E+05 1.600E-01 4.589E-02 7.560E+01 2.700E+02 5 5.000E+05 6.012E-01 1.724E-01 -6.300E+01 1.800E+02 6 6.000E+05 8.387E-01 2.405E-01 -2.160E+01 2.700E+02 7 7.000E+05 6.193E-01 1.776E-01 1.980E+01 3.600E+02 8 8.000E+05 1.600E-01 4.589E-02 6.120E+01 4.500E+02 9 9.000E+05 2.763E-01 7.923E-02 -7.740E+01 3.600E+02 10 1.000E+06 4.924E-01 1.412E-01 -3.600E+01 4.500E+02
© Copyright Ned Mohan 2008 33
FOURIER COMPONENTS OF TRANSIENT RESPONSE V(vo) DC COMPONENT = 6.083044E+00 HARMONIC FREQUENCY FOURIER NORMALIZED PHASE NORMALIZED NO (HZ) COMPONENT COMPONENT (DEG) PHASE (DEG) 1 1.000E+05 1.795E-02 1.000E+00 1.343E+02 0.000E+00 2 2.000E+05 3.400E-03 1.894E-01 1.746E+02 -9.403E+01 3 3.000E+05 8.465E-04 4.715E-02 -1.489E+02 -5.518E+02 4 4.000E+05 1.226E-04 6.826E-03 -1.492E+02 -6.865E+02 5 5.000E+05 1.602E-04 8.922E-03 1.447E+02 -5.269E+02 6 6.000E+05 1.718E-04 9.570E-03 1.707E+02 -6.352E+02 7 7.000E+05 1.158E-04 6.448E-03 -1.626E+02 -1.103E+03 8 8.000E+05 5.644E-05 3.143E-03 -1.560E+02 -1.231E+03 9 9.000E+05 4.483E-05 2.497E-03 1.751E+02 -1.034E+03 10 1.000E+06 5.570E-05 3.102E-03 1.789E+02 -1.164E+03
© Copyright Ned Mohan 2008 34
Currents
Time
450us 455us 460us 465us 470us 475us 480us 485us 490us 495us 500usI(L) I(C) I(R)
0A
10A
-4A
16A
RiLi
Ci
© Copyright Ned Mohan 2008 35
Frequency Analysis
SwitchingWaveform_AC-Analysis.Sch
© Copyright Ned Mohan 2008 36
Simulation Results
Frequency
100Hz 1.0KHz 10KHz 100KHz 1.0MHzDB(V(vo)/V(VA))
-100
-50
0
50
(100.000K,-45.867)
© Copyright Ned Mohan 2008 37
Transistor and diode forming a switching power-pole in a Buck converter
Figure 1-24 Transistor and diode forming a switching power-pole in a Buck converter. (b) (c)
(a)
inV
−
+Li
Li Li
1Aq = 0Aq =
+
−oV
+
−oV
+
−oV
inV
−
+
inV
−
+
(b) (c)(c)
(a)
inV
−
+Li
Li Li
1Aq = 0Aq =
+
−oV
+
−oV
+
−oV
inV
−
+
inV
−
+
© Copyright Ned Mohan 2008 38
Hardware Lab: very low-costSwitching Power - Pole Board
Magnetics Plug - In Board
Feedback Control Plug - In Board
Experiments:- Buck, Boost, Buck-Boost- Feedback Control: Voltage-
Mode, Peak-Current-Mode- Flyback, Forward
USERS MANUAL
www.ece.umn.edu/groups/power
© Copyright Ned Mohan 2008 39
RECENT AND POTENTIAL ADVANCEMENTS
• Devices that can handle voltages in kVs and currents in kAs
• ASICs
• DSPs
• Micro-controllers
• FPGA
• Integrated and intelligent power modules
• Packaging
• SiC-based solid-state devices
• High energy density capacitors
© Copyright Ned Mohan 2008 40
CONCEPT OF PEBB
It has numerous benefits such as technology insertion and upgrade via standard interfaces, reduced maintenance via plug and play modules, reduced cost via increased product development efficiency, reduced time to market, reduced commissioning cost, reduced design and development risk, a n d i n c r e a s e d c o m p e t i t i o n i n c r i t i c a l t e c h n o l o g i e s [ 1 4 ] .
Power Electronics Building Block (PEBB) [15] is a broad concept that incorporates the progressive integration of power devices, gate drives, and other components into building blocks, with clearly defined functionality that provides interface capabilities able to serve multiple applications. This building block approach results in reduced cost, losses, weight, size, and engineering effort for the application and maintenance of power electronics systems. Based on the functional specifications of PEBB and the performance requirements of the intended applications, the PEBB designer addresses the details of device stresses, stray inductances, switching speed, losses, thermal management, protection, measurements of required variables, control interfaces, and potential integration issues at all levels.
© Copyright Ned Mohan 2008 41
SummaryPower Electronics an Enabling TechnologyApplicationsNeed for High Efficiency and High Power DensityStructure of Power Electronic ConvertersSwitching Power-Pole as the Building BlockPotential for Advancements