寄生电感对SiC MOSFET开关损耗测量的影响

The Influence of Parasitic Inductance on SiC MOSFET Switching Loss Measurement

双脉冲测试是评估器件动态特性的重要手段。测试电路的寄生参数将对测试结果产生直接影响。基于双脉冲测试平台,研究并评估寄生电感对碳化硅(SiC)金属氧化物半导体场效应管(MOSFET)开关损耗测量的影响。首先,用低感电阻替换测试电路中的续流二极管,通过对母线电容放电状态下的电压和电流波形进行高阶多项式拟合,计算得到双脉冲测试电路主回路的寄生参数。其次,通过调整主回路跳线接口处的空心小电感感值,获得不同主回路寄生电感值的双脉冲测试电路。最后,对比分析了不同电压电流测试条件下寄生电感对开关损耗测量的影响。研究结果表明:随着主回路寄生电感的增大,在开通阶段漏源电压下降变快,开通损耗随之减小;而在关断阶段漏源电压过冲增大,关断损耗随之增大,总开关损耗几乎不变。

Double pulse test is usually used to evaluate the dynamic performance of power devices.The parasitic parameters existed in the test circuit will affect the test results directly.The influence of parasitic inductance on the switching loss measurement of silicon carbide(SiC)metal-oxide-semiconductor field-effect transistor(MOSFET)is studied and evaluated.First,replace the freewheeling diode in the test circuit with a low-inductance resistance with same package,and calculate the parasitic parameters of the main circuit of the double-pulse test circuit through polynomial fitting of the voltage and current waveforms under the discharge state of the bus capacitor.Secondly,by adjusting the small hollow inductance value at the jumper interface of the main loop,a double pulse test circuit with different parasitic inductance values of the main loop is obtained.Then,the influence of parasitic inductance on switching loss measurement under different voltage and current test conditions is compared and analyzed.The research results show that as the parasitic inductance of the main circuit increases,the drain-source voltage drops faster during the turn-on phase,and the turn-on loss decreases,while the drain-source voltage overshoot increases during the turn-off phase,and the turn-off loss increases accordingly.The total switching loss is almost unchanged.