IGBT driving aspectZhou Yizheng
Copyright © Infineon Technologies 2009. All rights reserved.
IGBT driving
Driving voltage level
Effect of turn on/off
¬ Rge, Cge, Lg
¬ Driving capability
Isolation
Thermal
Protection
¬ Parasitic turn on
¬ Over voltage
¬ Short circuit/over current
Copyright © Infineon Technologies 2009. All rights reserved.
Driving voltage level
Effect to Vcesat
Vge , Vcesat
Tvj=125C
Tvj=125C
Effect to short cicuit
Vge , Isc ( tsc)
note : max. allowed Vge is 20V
Positive voltage
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Driving voltage level
Miller capability effect
Negative voltage
¬ To guarantee safety off state, avoid parasitic miller turn on
¬ Turn on delay increase (dead time)
¬ Slightly reduce tf and Eoff
¬ Increase driving power
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Effect of turn on/off
Rgon
Control of dv/dt and di/dt with gate resistor
Turn-on with nominal gate resistor (datasheet value):
dv/dt = 0.9kV/µsdi/dt = 6.4kA/µsICpeak = 2.4kAEon = 816mWs
Turn-on with smaller than nominal gate resistor:
dv/dt = 1.4kV/µsdi/dt = 8.7kA/µsICpeak = 2.7kAEon = 544mWs
Turn-on with larger than nominal gate resistor:
dv/dt = 0.3kV/µsdi/dt = 3.0kA/µsICpeak = 1.8kAEon = 2558mWs
Copyright © Infineon Technologies 2009. All rights reserved.
Effect of turn on/off
Rgoff
Control of dv/dt and di/dt with gate resistor
•dv/dt is controllable with gate resistor. A larger resistor will result in a smaller dv/dt.•di/dt is only controllable if the gate voltage doesn’t drop below the Miller Plateau level before IC starts to decrease. This is in general the case for a gate resistor value close to the datasheet value. With larger resistors a control of di/dt starts to work.
Copyright © Infineon Technologies 2009. All rights reserved.
Effect of turn on/off
Range Determined by
Condition Influenced by Influence on
1 VGE < VGEth Ciss = const RG, CGE tdon
2 VGEth < VGE < VGEM Ciss = const RG, CGEdi/dt
3 VGE = VGEM VGE = const RG, CGCdv/dt
Cge
Independently control of dv/dt and di/dt
Copyright © Infineon Technologies 2009. All rights reserved.
For similar Eon, we can:
Rge Cge Eon Di/dt Ipeak tdon Vge_p
4.6ohm 0nf 650mJ 3283kA/us
1.487kA 1.76us 13.6V
1.7ohm 200nf 635mJ 2492kA/us
1.386kA 1.67us 13.7V
4.6ohm0nF 1.7ohm200nF
Copyright © Infineon Technologies 2009. All rights reserved.
For similar di/dt, we can:
Rge Cge Eon Di/dt Ipeak tdon Vge_p
2.6ohm 0nf 437mJ 4270kA/us
1.639kA 1.29us 14.0V
1.7ohm 46nf 386mJ 4324kA/us
1.635kA 1.23us 15.0V
2.6ohm0nF 1.7ohm46nF
Copyright © Infineon Technologies 2009. All rights reserved.
Rge vs. Cge
Using Cge shows better Eon*di/dt coefficient
Using Cge can significantly increase driving power
P=∆U*(Qge+Cge*∆U)*f
Using Cge can significantly increase driving peak current, require more powerful driver (output peak current capability)
The tolerance of Cge should be taken care when used in IGBT paralleling application
Using Cge may cause gate current oscillation, which leads to higher gate peak voltage.
Copyright © Infineon Technologies 2009. All rights reserved.
Cable length influence
With short cable With long cable
Calbe Rge Cge Eon Di/dt Ipeak tdon Vge_p
Short 0.9ohm 0nf 196mJ 6128kA/us
1.978kA
0.92us 14.7V
Long 0.9ohm 0nf 87mJ 6920kA/us
2.220kA
0.92us 18.3V
Copyright © Infineon Technologies 2009. All rights reserved.
For similar Eon, we can:
With fixed Cge
With fixed Rge
Calbe Rge Cge Eon Di/dt Ipeak tdon Vge_p
Short 0.9ohm 22nf 210mJ 5882kA/us
1.908kA
0.92us 17.0V
Long 1.7ohm 22nf 231mJ 5587kA/us
1.874kA
1.21us 17.5V
Calbe Rge Cge Eon Di/dt Ipeak tdon Vge_p
Short 1.7ohm 22nf 351mJ 4717kA/us
1.711kA
1.17us 15.8V
Long 1.7ohm 91nf 347mJ 4065kA/us
1.673kA
1.39us 15.6V
Copyright © Infineon Technologies 2009. All rights reserved.
Cable length influence
Cable length (Lg) shows similar Eon*di/dt coefficient as Rge, This mainly due to Lg effect both during di/dt period and dv/dt period (same as Rge)
Long cable significantly induce the turn on delay time
Long cable is a EMI receiver, which can cause Vge spike and unstable.
Loosing gate cable inductance will significantly increase Eon, which should especially paid attention in active adaptor design.
Adaptor board Rge Cge Eon Di/dt Ipeak
Active 1.0ohm 0nf 332mJ 5650kA/us 1.708kA
Passive(8mm) 1.0ohm 0nf 187mJ 7700kA/us 1.895kA
Long cable should be avoid to be used. But loosing gate inductance should also be paid attention
Copyright © Infineon Technologies 2009. All rights reserved.
Effect of turn on/off
Driving capability
¬ Peak current capability
¬ Power capability
Maximum driver peak current
U = 30V @ 15V switching
Driver power
internGexternGG(min)Gmax RR
ΔU
R
ΔUI
2issGate
Gate
GateDrivertot
ΔUC3...5fPor
ΔUQfP
PPP
Slow down turn on/off speed
Driver losses
Vge goes down
Power supply losses
Copyright © Infineon Technologies 2009. All rights reserved.
Effect of turn on/off
Turn on/off criteria
Redundant information on di/dt and dv/dt
2000
1000
0
1000
2000
3000
time [400ns/div]
VR
[5
00
V/d
iv]
IR
[5
00
A/d
iv]
1
23
!
0
0 1000 2000 30000
1000
2000
VR(t) [V]
IR(t
) [A
]
locus iR(t)*vR(t)
1
2
3
!
0
Diode SOA
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Isolation
+ -Optocoupler
Optical Fiber
High isolation capability Aging of electrical characteristic
Reduced reliability due to aging
No energy transmission
MonolithicLevel Shifter
Cost effective
Integration of logic suitable
No galvanic isolation
EMI sensitivity
No energy transmission
DiscreteTransformer
Very high isolation Capability
Energy transmission possible
Expensive
Device Volume
CorelessTransformer (CLT)
High isolation capability
Very cost effective
Easy integration of logic function
No energy transmission
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Isolation
Isolation transformer
¬ Isolation test
¬ Partial discharge test
¬ Parasitic capacitor (Primary - secondary)
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Thermal
Influenced parameters
Module case temperature
Driving power (switching frequency, Qg)
Driving peak current
Sensitive parts
Gate resistor
Booster
Power supply
Fiber
Copyright © Infineon Technologies 2009. All rights reserved.
Thermal
If system internal ambient temperature is known.
From delt Tca, we can check temperature rise due to module itself heating
Adding temperature rise due to driving signal, real driver board temperature can be gotten.
System cooling can significant improve driver cooling condition
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
UVLO
Interlock / generating deadtime
Vge over voltage
Parasitic turn on
Short circuit protection
Over voltage protection (for short circuit off)
¬ Active Clamping
¬ DVRC (Dynamik Voltage Raise Control)
¬ di/dt-Feedback
¬ Soft-Shut-Down
¬ Two-Level Turn-off
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
UVLO
¬ Avoid driving IGBT with low voltage causing thermal issue
¬ Avoid series break down
Interlock / generating deadtime
¬ Avoid short through by software mistake
¬ Hardware deadtime should be shorter than software deadtime
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
¬ Limitation of increase of gate voltage due to positive feedback over CGC and due to di/dt
¬ Limitation of short circuit currents
Methode 1Gate-Supply Clamping
Methode 2Gate-Emitter Clamping
Vge over voltage
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
Parasitic turn on
¬ minus voltage off
¬ separate gate resistors, using small Rgoff and big Rgon
¬ Additional gate emitter capacitor to shunt the Miller current
¬ Active Miller clamping
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Protection
Short circuit protection
Desaturation detect
Ic Vce
OC SC II
Vce
Ic
SC I
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Protection
Short circuit protection
Desaturation detect
Based on fixed reference voltage Based on variable reference voltage
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
Short circuit protection
Desaturation detect
Over current protection?
– Noise immunity is poor
– Blanking time hard to set for fixed reference voltage concept, especially for high voltage module
– Current protect point hard to be accurate
¬ Directly detect collector current
¬ Digital controller to detect di/dt
¬ By system current sensor
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
Over voltage protection
¬ Active clamping
Copyright © Infineon Technologies 2009. All rights reserved.
Protection
Over voltage protection
¬ DVRC (Dynamic Voltage Raise Control)
uGE(t)
iC(t)
uCE(t)
dic/dt=11kA/µs@ Tj=25°C
RG=3.6EOFF=0.9J
uGE(t)
iC(t)
uCE(t)
dic/dt=3.4kA/µs@ Tj=25°C
RG=13EOFF=1.95J
+16V
-16V
PWM
IRFD 120
UF4007
UF4007
100pF
RG=1.5
FZ2400R17KE3
47R
15R
ZPD16
RMO
S
56
BYD77
BYD77
44H11
45H11
MFP-D
MFN-D
3xSM6T220A
RAC=15
4xSM6T220A
UAC
URAC
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Protection
Over voltage protection
¬ di/dt protection
Detect & comparison
Gate boost
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Protection
Over voltage protection
¬ Soft shut down
Rg
Rssd
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Protection
Over voltage protection
¬ Two level turn off
VGEDriver Out
VCEIC
VGEDriver Out
VCEIC
Without Two-Level Turn-OffVCE reaches 1000V
With Two-Level Turn-OffVCE reduced to 640V
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