一种IGBT串联功率模块的设计

Design of Series-connected IGBT Power Module

均压控制技术是IGBT串联应用的关键。提出将IGBT的均压过程分为开通动态过程、关断动态过程、拖尾电流阶段和稳态过程均压4个阶段。动态过程采用了门极补偿电容网络;针对拖尾电流衰减时间常数不一致的特点,给出了RC均压回路中吸收电容的计算公式;稳态阶段采用了并联均压电阻。在此基础上设计了一种IGBT串联功率模块,进行了高压大电流下2个IGBT串联的均压试验。试验结果表明:当串联母线总电压为2 k V(单个IGBT最大峰值电压1.85 k V)、回路电流为2 k A时,所设计的IGBT串联功率模块能够实现开通关断周期的全过程均压,动态和稳态的电压不均衡度均小于5%。

Voltage-balancingmethodisthekeytotheapplicationofseries-connectedIGBTs.Thevoltage-balancing process was divided into 4 stages:dynamic turning-on process,dynamic turning-off process,the tail current state and steady state,whose voltage-balancing methods were then proposed respectively:gate compensation capacitor network for dynamic process;RC voltage-balancing circuit designed for tail current state with the capacitance givenby a formula;and parallel-connected voltage-balancing resistance for the steady state. Based on the work above,power module of two series-connected IGBTs was designed and tested under high voltage and high current condition.The result shows that under the series total voltage 2 kV(1.85 kV maximum peak voltage for each IGBT)and 2 kAcurrent,the power module balances the voltage of the whole period of and turning on and off process,and both of the voltage-unbalance-rate of dynamic and steady state are less than 5%.