基于桥式电路的氮化镓开关损耗测试

Test of Gallium Nitride Switching Loss Based on Bridge Circuit

与传统硅基器件相比,氮化镓GaN(gallium nitride)功率器件具有更快的开关速度,更小的开关损耗并且无反向恢复损耗,这使得氮化镓器件在高频和高功率密度应用场合具有突出优势。高频工况下高精度测试方法是目前研究的热点,其中双脉冲测试DPT(double pulse test)电路是器件动态性能测量的常用方法。然而,该方法必须采用漏极电流探头进行采样,而同轴分流器电流探头极大地增加了回路寄生电感,这与氮化镓实际工况差距非常大,将影响开关特性和损耗测试的准确性。提出了一种适用于桥式氮化镓电路的新颖测试方法,该方法无需采用无感电阻即可测量氮化镓器件的开关损耗。搭建了基于氮化镓的降压变换器进行实验,验证了该方法的有效性。

Compared with the traditional silicon-based devices,gallium nitride(GaN)power devices have a faster switching speed,smaller switching loss and no reverse recovery loss,showing obvious advantages in high-frequency and highpower density application scenarios.At present,the high-precision test method under high-frequency conditions is a research hotspot,in which the double pulse test(DPT)circuit is a common method for measuring the dynamic performance of devices.However,the drain current probe must be used for sampling when using this method,while the coaxial shunt current probe greatly increases the loop parasitic inductance.This is quite different from the actual working condition of GaN,and will affect the switching characteristics and the accuracy of loss test.A novel test method for bridge GaN circuits is proposed,which can be used to measure the loss of GaN devices in a practical circuit without non-inductive resistance.A GaN-based buck converter was built,and experimental results verified the effectiveness of the proposed method.