IGBT驱动电路分析.ppt

IGBT Gate Driver Calculation,Gate Driver Requirement,What is the most important requirement for an IGBT driver ?,Gate Peak current,Conditions for a safety 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”,How to find the 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,Difference between Trench- and SPT Technology,Trench Technology needs a smaller Gate charge Driver has to provide a smaller Gate charge SPT Technology needs more Gate charge compared to Trench Technology Driver has to provide a higher Gate charge,Driver performance different IGBT technologies needs different gate charge,Trench IGBT with same chip current,Gate charge is 2.3 uC,Driver performance different IGBT technologies needs different gate charge,SPT IGBT with same chip current,Gate charge is 3 uC,Demands for the gate driver,The suitable gate driver must 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),-8,15,1390,Determination of Gate Charge,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,Calculation of the average current,Calculation of average current: IoutAV = P / U V = +Vg + -Vg with P = E * fsw = QG * V * fsw IoutAV = QG * fsw = 1390nC * 10kHz = 13.9mA,Absolute value,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 consider the transformed average power from the transformer) Average current Is related to the transformer,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 = 2.9 A,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“ 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 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.,Choice of the suitable gate driver,The absolute maximum ratings of the suitable 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,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,PCB Driver and PCB mountable Driver for single, half bridge, six pack modules integrated potential-free power supply switching frequency up to 100kHz output peak current up to 30A Gate charge up to 30C dv/dt capability up to 75kV/s high EMI immunity TTL- an CMOS-compatible inputs and outputs with potential isolation via opto coupler or transformer (isolation up to 4kVAC) protection (interlock, short pulse suppression, short circuit protection via VCE -monitoring, under voltage monitoring, error memory and error feedback),SEMIDRIVER,Product overview (important parameters),Driver core for IGBT modules,Simple Adaptable Expandable Short time to market Two versions SKYPER (standard version) SKYPER PRO (premium version),Assembly on SEMiXTM 3 Modular IPM,SKYPER Driver board SEMIX 3 IGBT half bridge with spring contacts,SKYPER more than a solution,modular IPM using SEMiX,with adapter board,solder directly in your main board,take 3 for 6-packs,Selection of the right IGBT driver,Advice,Problem 1- Cross conduction,Low impedance,Cross conduction behavior,vCE,T1(t) iC,T1(t),VCC,IO,0,t,vGE,T1(t) vGE,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?,IGBT - Parasitic capacitances,When the outer voltage potential V changes, the load Q has to follow This leads to a displacement current iV,Switching: Detailed for T2,iv,T2,vCE,T2,vGE,T2,iC,T2,RGE,T2,CGC,T2,Diode D2 switches off and takes over the voltage T2 “sees” 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 recommends: VGG- = -5-8-15 V),Problem 2 - gate protection,Z 16 -18,Gate clamping - how ?,Z18,PCB design because no cable close to the IGBT,Problem 3 -booster for the gate current,Use MOSFET for the booster,For small IGBTs is ok,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 dissipation of IGBT (short circuit current x time) Chip temperature level,Problem 5 dead time between top and bottom IGBT,Turn on and turn off delay must be symetrical,Dead time explanati