1、1 Semikron Hong Kong Norbert Pluschke 07.10.2005 IGBT Gate Driver Calculation Gate Driver Requirement 2 Semikron Hong Kong Norbert Pluschke 07.10.2005 What is the most important requirement for an IGBT driver?Gate Peak current 3 Semikron Hong Kong Norbert Pluschke 07.10.2005 Conditions for a safety
2、operation?Which gate driver is suitable for the module SKM 200 GB 128D?Design parameters:fsw=10 kHz Rg=?reverse recovery current Diode should be-1.5 x I diode by 80 degree case 130A x 1.5=195A Gate resistor in range of“test gate resistor”4 Semikron Hong Kong Norbert Pluschke 07.10.2005 How to find t
3、he right gate resistor?Rg=7 Ohm Two gate resistors are possible for turn on and turn off Ron=7 Ohm Roff=10 Ohm 195A max reverse recovery current 5 Semikron Hong Kong Norbert Pluschke 07.10.2005 Difference between Trench-and SPT Technology?Trench Technology needs a smaller Gate charge?Driver has to p
4、rovide a smaller Gate charge?SPT Technology needs more Gate charge compared to Trench Technology?Driver has to provide a higher Gate charge 6 Semikron Hong Kong Norbert Pluschke 07.10.2005 Driver performance different IGBT technologies needs different gate charge?Trench IGBT with same chip current G
5、ate charge is 2.3 uC 7 Semikron Hong Kong Norbert Pluschke 07.10.2005 Driver performance different IGBT technologies needs different gate charge?SPT IGBT with same chip current Gate charge is 3 uC 8 Semikron Hong Kong Norbert Pluschke 07.10.2005 Demands for the gate driver?The suitable gate driver m
6、ust provide the required?Gate charge(QG)power supply of the driver must provide the average power?Average current(IoutAV)power supply?Gate pulse current(Ig.pulse)most important?at the applied switching frequency(fsw)9 Semikron Hong Kong Norbert Pluschke 07.10.2005-8 15 1390 Determination of Gate Cha
7、rge?Gate charge(QG)can be determined from fig.6 of the SEMITRANS data sheet?QG=1390nC The typical turn-on and turn-off voltage of the gate driver is VGG+=+15V VGG-=-8V 10 Semikron Hong Kong Norbert Pluschke 07.10.2005 Calculation of the average current?Calculation of average current:?IoutAV=P/?U?V=+
8、Vg+-Vg?with P=E*fsw=QG*?V*fsw?IoutAV=QG*fsw =1390nC*10kHz=13.9mA Absolute value 11 Semikron Hong Kong Norbert Pluschke 07.10.2005 Power supply requirements?Gate charge?The power supply or the transformer must provide the energy(Semikron is using pulse transformer for the power supply,we must conside
9、r the transformed average power from the transformer)?Average current?Is related to the transformer 12 Semikron Hong Kong Norbert Pluschke 07.10.2005 Calculation of the peak gate current?Examination of the peak gate current with minimum gate resistance?E.g.RG.on=RG.off=7?Ig.puls?V/RG+Rint =23V/7?+1?
10、=2.9 A 13 Semikron Hong Kong Norbert Pluschke 07.10.2005 Pulse power rating of the gate resistor?P total Gate resistor?Ppulse Gate resistor =I out AV x?V?More information:The problem occurs when the user forgets about the peak power rating of the gate resistor.The peak power rating of many ordinary
11、SMD resistors is quite small.There are SMD resistors available with higher peak power ratings.For example,if you take an SKD driver apart,you will see that the gate resistors are in a different SMD package to all the other resistors(except one or two other places that also need high peak power).The
12、problem was less obvious with through hole components simply because the resistors were physically bigger.The Philips resistor data book has a good section on peak power ratings.14 Semikron Hong Kong Norbert Pluschke 07.10.2005 Choice of the suitable gate driver?The absolute maximum ratings of the s
13、uitable gate driver must be equal or higher than the applied and calculated values?Gate charge QG=1390nC?Average current IoutAV=13,9mA?Peak gate current Ig.pulse=2.9 A?Switching frequency fsw=10kHz?Collector Emitter voltage VCE=1200V?Number of driver channels:2(GB module)?dual driver 15 Semikron Hon
14、g Kong Norbert Pluschke 07.10.2005 Comparison with the parameters in the driver data sheet Calculated and applied values:?Ig.pulse=2.9 A Rg=7?+R int?IoutAV=13.9mA?fsw=10kHz?VCE=1200V?QG=1390nC?According to the applied and calculated values,the driver e.g.SKHI 22A is able to drive SKM200GB128D 17 Sem
15、ikron Hong Kong Norbert Pluschke 07.10.2005 Product overview(important parameters)18 Semikron Hong Kong Norbert Pluschke 07.10.2005 Driver core for IGBT modules?Simple?Adaptable?Expandable?Short time to market?Two versions?SKYPER?(standard version)?SKYPER?PRO(premium version)19 Semikron Hong Kong No
16、rbert Pluschke 07.10.2005 Assembly on SEMiXTM 3 Modular IPM?SKYPER?Driver board?SEMIX 3 IGBT half bridge with spring contacts 20 Semikron Hong Kong Norbert Pluschke 07.10.2005 SKYPER?more than a solution modular IPM using SEMiX?with adapter board solder directly in your main board take 3 for 6-packs
17、 21 Semikron Hong Kong Norbert Pluschke 07.10.2005 Selection of the right IGBT driver Advice 22 Semikron Hong Kong Norbert Pluschke 07.10.2005 Problem 1-Cross conduction Low impedance 23 Semikron Hong Kong Norbert Pluschke 07.10.2005 Cross conduction behavior vCE,T1(t)iC,T1(t)VCC IO 0 t vGE,T1(t)vGE
18、,T2(t)VGE,Io VGE(th)0 t VGG+VCC IO 0 t vCE,T2(t)=vF,D2(t)iF,D2(t),iC,T2(t)T1 D1 T2 D2 iv,T2?Why changes VGE,T2 when T1 switches on?24 Semikron Hong Kong Norbert Pluschke 07.10.2005 IGBT-Parasitic capacitances dtdvCiVCQv?When the outer voltage potential V changes,the load Q has to follow?This leads t
19、o a displacement current iV 25 Semikron Hong Kong Norbert Pluschke 07.10.2005 Switching:Detailed for T2 dtdvCiT2CE,T2GC,T2v,?iv,T2 T2GE,T2v,T2GE,Riv?vCE,T2 vGE,T2 iC,T2 RGE,T2 CGC,T2 vCE,T2(t)VCC 0 t 0 t iC,T2(t)iv,T2(t)vGE,T2(t)VGE(th)0 t VGG+?Diode D2 switches off and takes over the voltage?T2“see
20、s”the voltage over D2 as vCE,T2?With the changed voltage potential,the internal capacitances change their charge?The displacement current iv,T2 flows via CGC,T2,RGE,T2 and the driver?iv,T2 causes a voltage drop in RGE,T2 which is added to VGE,T2?If vGE,T2 VGE(th)then T2 turns on(Therefore SK recomme
21、nds:VGG-=-5-8-15 V)26 Semikron Hong Kong Norbert Pluschke 07.10.2005 Problem 2-gate protection Z 16-18 27 Semikron Hong Kong Norbert Pluschke 07.10.2005 Gate clamping-how?Z18 PCB design because no cable close to the IGBT 28 Semikron Hong Kong Norbert Pluschke 07.10.2005 Problem 3-booster for the gat
22、e current Use MOSFET for the booster For small IGBTs is ok 29 Semikron Hong Kong Norbert Pluschke 07.10.2005 Problem 4-Short circuit?Over voltage?1200V-is chip level-consider internal stray inductance?+/-20V-gate emitter voltage-consider switching behavior of freewheeling diode?Over current?Power di
23、ssipation of IGBT(short circuit current x time)?Chip temperature level 30 Semikron Hong Kong Norbert Pluschke 07.10.2005 Problem 5 dead time between top and bottom IGBT Turn on and turn off delay must be symetrical 31 Semikron Hong Kong Norbert Pluschke 07.10.2005 Dead time explanation 32 Semikron H
24、ong Kong Norbert Pluschke 07.10.2005 Dead time explanation?Example:?Dead time=3 us logic level?Turn on delay 1 us?Turn off delay 2.5 us Td toff delay+ton delay=real dead time Real dead time:3us (2.5us+1us)=1.5 us 33 Semikron Hong Kong Norbert Pluschke 07.10.2005 Our final recommendation?IGBT driver
25、must provide the peak Gate current?The stray inductance should be very small in the gate driver circuit?Gate/Emitter resistor and Gate/Emitter capacitor(like Ciss)very close to the IGBT?Turn off status must have a very low impedance?High frequency capacitors very close to the IGBT driver booster?Dont use bipolar transistors for the booster?Protect the Gate/Emitter distance against over voltage?Dont mix;?Peak current?Gate charge 34 Semikron Hong Kong Norbert Pluschke 07.10.2005
