Welcome to
EJ2300 Power Electronics
Basics
DC/DC converters
DC-motor
Diode and thyristor converters
Power semiconductors (web-based)
Inverters
Switching DC power supplies
Copyright © 2003
by John Wiley & Sons, Inc.
1-1
Power Electronic Systems
• Block diagram
• Role of Power Electronics
• Reasons for growth (power semiconductors, digital
electronics, renewables, electric vehicles)
HPN 2012-09-03
1-2
Linear Power Supply
• Series transistor as an adjustable resistor
• Low Efficiency
• Heavy and bulky
Copyright © 2003
by John Wiley & Sons, Inc.
1-3
Basic Principle of Switch-Mode Synthesis
• Constant switching frequency
• pulse width controls the average
• L-C filters the ripple
Copyright © 2003
by John Wiley & Sons, Inc.
1-4
Switch-Mode Power Supply
• Transistor as a switch
• High Efficiency
• High-Frequency Transformer
Copyright © 2003
by John Wiley & Sons, Inc.
1-5
AC Motor Drive
• Converter 1 rectifies line-frequency ac into dc
• Capacitor acts as a filter; stores energy; decouples
• Converter 2 synthesizes low-frequency ac to motor
• Polarity of dc-bus voltage remains unchanged
– ideally suited for transistors of converter 2
Copyright © 2003
by John Wiley & Sons, Inc.
1-6
Applications
• Controlled DC power supplies
• Motor drives for various applications
(industry, transport)
• Grid applications (HVDC, SVC, StatCom,
TCSC)
• Windpower
• Photovoltaics
Copyright © 2003
by John Wiley & Sons, Inc.
1-7
Honda Insight
HPN 2012-09-03
1-8
Thyristor valve for HVDC
500 kV, 1500 MW
Source: ABB
1-9
Thyristor Controlled Series Compensator
400 kV,
394 Mvar fixed, 71 Mvar controlled
Source: ABB
1-10
Power oscillation damping with
TCSC
500 kV, 2000 MW line
a)
Source: ABB
b)
1-11
IGBT press-pack modules
Source: ABB
1-12
IGBT stacks
Source: ABB
1-13
Valve assembly
Source: ABB
1-14
Cooling system
Source: ABB
1-15
High-voltage PEX cable
Source: ABB
1-16
Electrostatic precipitator
HPN 2012-09-03
1-17
Diodes
• On and off states controlled by the power circuit
Copyright © 2003
by John Wiley & Sons, Inc.
1-18
Thyristor
Anode
Gate
Cathode
Copyright © 2003
by John Wiley & Sons, Inc.
1-19
Generic Switch Symbol
• Idealized switch symbol
• When on, current can flow only in the direction of the arrow
• Instantaneous switching from one state to the other
• Zero voltage drop in on-state
• Infinite voltage and current handling capabilities
Copyright © 2003
by John Wiley & Sons, Inc.
1-20
Switching Characteristics (linearized)
Switching Power Loss is
proportional to:
• switching frequency
• turn-on and turn-off times
Copyright © 2003
by John Wiley & Sons, Inc.
1-21
Switching speed
• Why do we want to switch fast?
Low switching losses
Well defined voltage waveform
• Why do we want to switch slowly?
Voltage sharing
EMI
Electric stress on insulation systems
HPN 2012-09-03
1-22
MOSFETs
• Easy to control by the gate
• Optimal for low-voltage operation at high switching frequencies
• On-state resistance a concern at higher voltage ratings
Copyright © 2003
by John Wiley & Sons, Inc.
1-23
IGBT
Copyright © 2003
by John Wiley & Sons, Inc.
1-24
IGBT module
Source: Semikron
1-25
IGBT Datasheet
Source: Semikron
1-26
Bond wire lift-off
HPN 2012-09-03
1-27
Soldering delamination
HPN 2012-09-03
1-28
Source: ABB
1-29
Approximation of voltage drop
[V]
2
1.945
1.5
ut
i
Ui
1
i
UV
t0
u
u
rt 
i
0.5
0
0
0
0
HPN 2012-09-03
5
10
iIt i
15
20
[A]
20
1-30
Voltage drop
Von
MOSFET
IGBT
Diode
Ion
HPN 2012-09-03
1-31
Review of basics
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•
•
•
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Steady state
Mean value, RMS-value
Phasor representation
Active, reactive, and complex power
Three-phase circuits
Inductor
Capacitor
Copyright © 2003
by John Wiley & Sons, Inc.
1-32
Block Diagram of DC-DC Converters
• Functional block diagram
Copyright © 2003
by John Wiley & Sons, Inc.
1-33
DC-DC converter types
HPN 2012-09-03
1-34
Stepping Down a DC Voltage
Copyright © 2003
by John Wiley & Sons, Inc.
1-35
Step-Down DC-DC Converter
• Pulsating input to
the low-pass filter
Copyright © 2003
by John Wiley & Sons, Inc.
1-36
Step-Down DC-DC Converter: Waveforms
• Steady state; inductor current flows continuously
Copyright © 2003
by John Wiley & Sons, Inc.
1-37