power electronics chapter 9 practical application issues of power semiconductor devices
TRANSCRIPT
Power ElectronicsPower Electronics
Chapter 9 Practical Application Issues
of Power Semiconductor Devices
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OutlineOutline9.1 Gate drive circuit 9.1 Gate drive circuit
9.2 Protection of power semiconductor devices9.2 Protection of power semiconductor devices
9.3 Series and parallel connections of power 9.3 Series and parallel connections of power semiconductor devicessemiconductor devices
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9.1 Gate drive circuit9.1 Gate drive circuitBasic function of gate drive circuit:Basic function of gate drive circuit: Generate gate signals to turn-on or turn-off power Generate gate signals to turn-on or turn-off power
semiconductor device according to the commanding semiconductor device according to the commanding signals from the control circuit.signals from the control circuit.
Other functions of gate drive circuit:Other functions of gate drive circuit:
Reduce switching time (including turn-on time and turn-Reduce switching time (including turn-on time and turn-off time)off time)Reduce switching loss (including turn-on loss and turn-Reduce switching loss (including turn-on loss and turn-off loss) and improve efficiencyoff loss) and improve efficiencyImprove protection and safety of the converterImprove protection and safety of the converter
Gate drive circuits provided by power semiconductorGate drive circuits provided by power semiconductormanufacturers and Integrated gate drive chips aremanufacturers and Integrated gate drive chips aremore and more widely used.more and more widely used.
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Electrical isolation in the gate drive circuitElectrical isolation in the gate drive circuit
Gate drive circuit usually pGate drive circuit usually provides the electrical isolatirovides the electrical isolation between control circuit on between control circuit and power stage. and power stage.
Two ways to provide electrTwo ways to provide electrical isolationical isolation– OpticalOptical
• Optocoupler, fiber opticsOptocoupler, fiber optics
• TransformerTransformer
– MagneticMagnetic
E
RUin
Uout
R1
ICID
LED
Phototransistor
Schematic of an optocoupler
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Thyristor gate current pulse requirmentsThyristor gate current pulse requirments
Shape of gate current Shape of gate current pulse waveform:pulse waveform:– Enhanced leading partEnhanced leading part
Magnitude requirement Magnitude requirement (for the enhanced leading (for the enhanced leading part and the other part)part and the other part)
Width requirement (for the Width requirement (for the enhanced leading part and enhanced leading part and the whole pulse)the whole pulse)
Power of the triggering Power of the triggering signal must be within the signal must be within the SOA of the gate I-V SOA of the gate I-V characteristicscharacteristics
I
t
IM
t1 t2 t3 t4
Ideal gate current pulse waveform for thyristors
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Typical thyristor gate triggering circuitTypical thyristor gate triggering circuit
T M
R 1
R 2
R 3
V 1
V 2
VD
1
VD
3
V D 2 R 4+ E 1 + E 2
In p u t fro mc o n tro l c irc u it
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Typical gate signal and gate drive circuit Typical gate signal and gate drive circuit for GTOfor GTO
O t
tO
u G
iG
5 0 k H z5 0 V
G T O
N 1
N 2
N 3
C 1 C 3
C 4
C 2 R 1
R 2
R 3
R 4
V 1
V 3
V 2
LV D 1
VD
2
V D 3
V D 4
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A typical gate drive circuit for IGBT based on A typical gate drive circuit for IGBT based on an integrated driver chipan integrated driver chip
13Error
indicating
Sensing
VCC
Interfacecircuit
Turn-offcircuit
Timer andreset circuit
Detectioncircuit
4
1
5
8
6
14
13
uo
VEE
81
5
4
6-10V
+15V
30V+5V
M57962L
14
ui1
Fast recovery diodetrr¡Ü0.2s
4.7k
3.1
100F
100F
M57962L integrated driver chipM57962L integrated driver chip
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9.2 Protection of power semiconductor 9.2 Protection of power semiconductor devicesdevices
Protection circuitsProtection circuits
Overvoltage protectionOvervoltage protection
Overcurrent protectionOvercurrent protection
Snubber circuits—specific protection circuits that Snubber circuits—specific protection circuits that can limit du/dt or di/dtcan limit du/dt or di/dt
Turn-on snubberTurn-on snubber
Turn-off snubberTurn-off snubber
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Causes of overvoltage on power Causes of overvoltage on power semiconductor devicessemiconductor devices
External reasonsExternal reasons
Overvoltage caused by operation of mechanic switOvervoltage caused by operation of mechanic switheshes
Overvoltage caused by thunder lighteningOvervoltage caused by thunder lightening
Internal reasonsInternal reasons
Overvoltage caused by the reverse recovery of dioOvervoltage caused by the reverse recovery of diode or thyristorde or thyristor
Overvoltage caused by the turning-off of fully-contrOvervoltage caused by the turning-off of fully-controlled devicesolled devices
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Measures to protect power semiconductor Measures to protect power semiconductor devices from overvoltagedevices from overvoltage
Lightening arrestorLightening arrestor
RC or RCD snubbers (will be discussed later)RC or RCD snubbers (will be discussed later)
Zener diode, Metal Oxide Varistor (MOV), Break Over Zener diode, Metal Oxide Varistor (MOV), Break Over
Diode (BOD)Diode (BOD)
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Measures to protect power semiconductor devicMeasures to protect power semiconductor devices from overcurrentes from overcurrent
Fuse Fuse
Circuit breakerCircuit breaker
Protection with current feedback control in the control cProtection with current feedback control in the control c
ircuitircuit
Protection with overcurrent detection in the gate drive cProtection with overcurrent detection in the gate drive c
ircuit—the fastest measureircuit—the fastest measure
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Functions and classifications of snubbersFunctions and classifications of snubbers
FunctionsFunctionsLimiting voltages applied to devices during turn-off transientsLimiting voltages applied to devices during turn-off transientsLimiting device currents during turn-on transientsLimiting device currents during turn-on transientsLimiting device current rising rate (di/dt) at device turn-onLimiting device current rising rate (di/dt) at device turn-onLimiting the rate of rise (du/dt) of voltages across devices duriLimiting the rate of rise (du/dt) of voltages across devices during device turn-offng device turn-offShaping the switching trajectory of the deviceShaping the switching trajectory of the device
ClassificationsClassificationsAccording to different switching transientsAccording to different switching transients– Turn-off snubber (sometimes just called snubber)Turn-off snubber (sometimes just called snubber)– Turn-on snubber Turn-on snubber
According to the treatment of energy According to the treatment of energy – Power dissipating snubberPower dissipating snubber– Lossless snubberLossless snubber
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Operation principle of typical snubbersOperation principle of typical snubbers
Circuit configurationCircuit configuration
R i
V D
L
V
T u rn -o nsn u b b e r
T u rn -o ffsn u b b e r
L iV D i
R s
C s
VD
st
uCEiC
O
without turn-on snubber
with turn-on snubber
with turn-offsnubber
without turn-off snubber
uCE
iC
Switching trajectory
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Other turn-off snubbersOther turn-off snubbers
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9.3 Series and parallel connections of 9.3 Series and parallel connections of power semiconductor devices power semiconductor devices
ObjectObject
To increase the capability to deal with voltage or currentTo increase the capability to deal with voltage or current
Issues and solutionsIssues and solutions
Series connectionSeries connection– Issue: even voltage sharingIssue: even voltage sharing
– Solutions: Solutions: • Selection of devices that are closer to each other in the characteristicsSelection of devices that are closer to each other in the characteristics• Voltage sharing circuitVoltage sharing circuit
Parallel connectionParallel connection– Issue: even current sharingIssue: even current sharing
– Solutions: Solutions: • Selection of devices that are closer to each other in the characteristicsSelection of devices that are closer to each other in the characteristics• Current sharing circuit and symmetrical circuit layoutCurrent sharing circuit and symmetrical circuit layout
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Series Connection of thyristorsSeries Connection of thyristors
Voltage sharing circuitVoltage sharing circuit– Steady-state voltage sharing circuitSteady-state voltage sharing circuit
– Dynamic voltage sharing circuitDynamic voltage sharing circuit
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Parallel Connection of Power MOSFETsParallel Connection of Power MOSFETs
Easy to realize because of the positive temperature of their on-Easy to realize because of the positive temperature of their on-
state resistancestate resistance
Need a small damping resistor in series with the individual gate Need a small damping resistor in series with the individual gate
connectionsconnections
Still need to select devices that are closer to each other in the Still need to select devices that are closer to each other in the
characteristicscharacteristics
Circuit layout should be symmetricalCircuit layout should be symmetrical