1、1Semikron Hong KongNorbert Pluschke 07.10.2005IGBT Gate Driver CalculationGate Driver Requirement2Semikron Hong KongNorbert Pluschke 07.10.2005What is the most important requirement for an IGBT driver?Gate Peak current3Semikron Hong KongNorbert Pluschke 07.10.2005Conditions for a safety operationnWh
2、ich gate driver is suitable for the module SKM 200 GB 128D?Design parameters:fsw=10 kHzRg=?reverse recovery current Diode should be-1.5 x I diode by 80 degree case 130A x 1.5=195AGate resistor in range of“test gate resistor”4Semikron Hong KongNorbert Pluschke 07.10.2005How to find the right gate res
3、istor?Rg=7 OhmTwo gate resistors are possible for turn on and turn offRon=7 OhmRoff=10 Ohm195A max reverse recovery current5Semikron Hong KongNorbert Pluschke 07.10.2005Difference between Trench-and SPT Technologyn Trench Technology needs a smaller Gate chargeu Driver has to provide a smaller Gate c
4、hargen SPT Technology needs more Gate charge compared to Trench Technologyu Driver has to provide a higher Gate charge6Semikron Hong KongNorbert Pluschke 07.10.2005Driver performance different IGBT technologies needs different gate chargen Trench IGBT with same chip currentGate charge is 2.3 uC7Semi
5、kron Hong KongNorbert Pluschke 07.10.2005Driver performance different IGBT technologies needs different gate chargen SPT IGBT with same chip currentGate charge is 3 uC8Semikron Hong KongNorbert Pluschke 07.10.2005Demands for the gate driver nThe suitable gate driver must provide the requiredGate cha
6、rge(QG)power supply of the driver must provide the average power Average current(IoutAV)power supplyGate pulse current(Ig.pulse)most important nat the applied switching frequency(fsw)9Semikron Hong KongNorbert Pluschke 07.10.2005-8 151390Determination of Gate Charge nGate charge(QG)can be determined
7、 from fig.6 of the SEMITRANS data sheet QG=1390nCThe typical turn-on and turn-off voltage of the gate driver isVGG+=+15VVGG-=-8V10Semikron Hong KongNorbert Pluschke 07.10.2005Calculation of the average currentnCalculation of average current:nIoutAV=P/U V=+Vg+-Vgnwith P=E*fsw=QG*V*fswn IoutAV=QG*fsw
8、=1390nC*10kHz=13.9mAAbsolute value11Semikron Hong KongNorbert Pluschke 07.10.2005Power supply requirementsn Gate chargeu The power supply or the transformer must provide the energy(Semikron is using pulse transformer for the power supply,we must consider the transformed average power from the transf
9、ormer)n Average currentu Is related to the transformer12Semikron Hong KongNorbert Pluschke 07.10.2005Calculation of the peak gate current nExamination of the peak gate current with minimum gate resistanceE.g.RG.on=RG.off=7Ig.puls V/RG+Rint =23V/7+1=2.9 A13Semikron Hong KongNorbert Pluschke 07.10.200
10、5Pulse power rating of the gate resistorn P total Gate resistoru Ppulse Gate resistor =I out AV x V u More information:The problem occurs when the user forgets about the peak power ratingof the gate resistor.The peak power rating of many ordinary SMD resistors is quite small.There are SMD resistors
11、available with higher peak powerratings.For example,if you take an SKD driver apart,you will seethat the gate resistors are in a different SMD package to all the otherresistors(except one or two other places that also need high peak power).Theproblem was less obvious with through hole components sim
12、ply because theresistors were physically bigger.The Philips resistor data book has a good section on peak power ratings.14Semikron Hong KongNorbert Pluschke 07.10.2005Choice of the suitable gate drivernThe absolute maximum ratings of the suitable gate driver must be equal or higher than the applied
13、and calculated valuesGate charge QG=1390nCAverage current IoutAV=13,9mAPeak gate current Ig.pulse=2.9 ASwitching frequency fsw=10kHzCollector Emitter voltage VCE=1200VNumber of driver channels:2(GB module)dual driver15Semikron Hong KongNorbert Pluschke 07.10.2005Comparison with the parameters in the
14、 driver data sheetCalculated and applied values:nIg.pulse=2.9 A Rg=7+R intnIoutAV=13.9mAnfsw=10kHznVCE=1200VnQG=1390nCnAccording to the applied and calculated values,the driver e.g.SKHI 22A is able to drive SKM200GB128D16Semikron Hong KongNorbert Pluschke 07.10.2005nPCB Driver and PCB mountable Driv
15、er for single,half bridge,six pack modulesnintegrated potential-free power supplynswitching frequency up to 100kHznoutput peak current up to 30AnGate charge up to 30Cndv/dt capability up to 75kV/snhigh EMI immunitynTTL-an CMOS-compatible inputs and outputs with potential isolation via opto coupler o
16、r transformer(isolation up to 4kVAC)nprotection(interlock,short pulse suppression,short circuit protection via VCE-monitoring,under voltage monitoring,error memory and error feedback)SEMIDRIVER17Semikron Hong KongNorbert Pluschke 07.10.2005Product overview(important parameters)18Semikron Hong KongNo
17、rbert Pluschke 07.10.2005Driver core for IGBT modules Simple Adaptable Expandable Short time to market Two versionsSKYPER(standard version)SKYPER PRO(premium version)19Semikron Hong KongNorbert Pluschke 07.10.2005Assembly on SEMiXTM 3 Modular IPM n SKYPER n Driver boardn SEMIX 3 IGBT half bridgewith
18、 spring contacts20Semikron Hong KongNorbert Pluschke 07.10.2005SKYPER more than a solutionmodular IPM using SEMiXwith adapter boardsolder directly in your main boardtake 3 for 6-packs21Semikron Hong KongNorbert Pluschke 07.10.2005 Selection of the right IGBT driverAdvice22Semikron Hong KongNorbert P
19、luschke 07.10.2005Problem 1-Cross conductionLow impedance23Semikron Hong KongNorbert Pluschke 07.10.2005Cross conduction behaviorvCE,T1(t)iC,T1(t)VCCIO0tvGE,T1(t)vGE,T2(t)VGE,IoVGE(th)0tVGG+VCCIO0tvCE,T2(t)=vF,D2(t)iF,D2(t),iC,T2(t)T1D1T2D2iv,T2n Why changes VGE,T2 when T1 switches on?24Semikron Hon
20、g KongNorbert Pluschke 07.10.2005IGBT-Parasitic capacitancesdtdvCiVCQvn When the outer voltage potential V changes,the load Q has to follow n This leads to a displacement current iV25Semikron Hong KongNorbert Pluschke 07.10.2005Switching:Detailed for T2dtdvCiT2CE,T2GC,T2v,iv,T2T2GE,T2v,T2GE,RivvCE,T
21、2vGE,T2iC,T2RGE,T2CGC,T2vCE,T2(t)VCC0t0tiC,T2(t)iv,T2(t)vGE,T2(t)VGE(th)0tVGG+u Diode D2 switches off and takes over the voltage u T2“sees”the voltage over D2 as vCE,T2u With the changed voltage potential,the internal capacitances change their chargeu The displacement current iv,T2 flows via CGC,T2,
22、RGE,T2 and the driveru iv,T2 causes a voltage drop in RGE,T2 which is added to VGE,T2u If vGE,T2 VGE(th)then T2 turns on(Therefore SK recommends:VGG-=-5-8-15 V)26Semikron Hong KongNorbert Pluschke 07.10.2005Problem 2-gate protectionZ 16-1827Semikron Hong KongNorbert Pluschke 07.10.2005Gate clamping-
23、how?Z18PCB design because no cable close to the IGBT28Semikron Hong KongNorbert Pluschke 07.10.2005Problem 3-booster for the gate currentUse MOSFET for the boosterFor small IGBTs is ok29Semikron Hong KongNorbert Pluschke 07.10.2005Problem 4-Short circuitn Over voltageu 1200V-is chip level-consider i
24、nternal stray inductanceu+/-20V-gate emitter voltage-consider switching behavior of freewheeling dioden Over currentu Power dissipation of IGBT(short circuit current x time)u Chip temperature level30Semikron Hong KongNorbert Pluschke 07.10.2005Problem 5 dead time between top and bottom IGBTTurn on a
25、nd turn off delay must besymetrical31Semikron Hong KongNorbert Pluschke 07.10.2005Dead time explanation32Semikron Hong KongNorbert Pluschke 07.10.2005Dead time explanationn Example:u Dead time=3 us logic levellTurn on delay 1 uslTurn off delay 2.5 us Td toff delay+ton delay=real dead time Real dead
26、time:3us (2.5us+1us)=1.5 us33Semikron Hong KongNorbert Pluschke 07.10.2005Our final recommendationn IGBT driver must provide the peak Gate currentn The stray inductance should be very small in the gate driver circuitn Gate/Emitter resistor and Gate/Emitter capacitor(like Ciss)very close to the IGBTn Turn off status must have a very low impedancen High frequency capacitors very close to the IGBT driver boostern Dont use bipolar transistors for the boostern Protect the Gate/Emitter distance against over voltagen Dont mix;u Peak currentu Gate charge34Semikron Hong KongNorbert Pluschke 07.10.2005
