一种改进型抑制SiC MOSFET桥臂串扰的门极驱动设计

Improved Gate Drive Design to Suppress Crosstalk of SiC MOSFET Bridge Arm

针对传统驱动中SiC MOSFET在高开关频率下其寄生参数造成的桥臂串扰更加严重,而现有抑制串扰驱动电路多以增加开关损耗、增长开关延时和增加控制复杂度为代价的问题,根据降低串扰产生过程中驱动回路阻抗的思路,提出1种在栅源极间增加PNP三极管串联二极管和电容的新型有源米勒钳位门极驱动设计,分析其工作原理,并对改进驱动电路并联电容参数进行计算设计;搭建直流母线电压为300 V的同步Buck变换器双脉冲测试实验平台,分别与传统串扰抑制电路、典型串扰抑制电路的正负向串扰电压尖峰抑制效果和开通关断速度进行对比分析。实验结果表明,所提串扰抑制驱动电路正负向电压尖峰分别比传统和典型串扰抑制电路降低了80%和40%,同时减少了32%的器件开关延时。

In the case of high switching frequency,the bridge arm crosstalk caused by the parasitic parameters of SiC MOSFET in the traditional drive are more serious.However,most of the existing crosstalk suppression drive circuits suppress the crosstalk at the expense of increasing the switching loss,prolonging the switching delay and adding the control complexity.Therefore,based on the idea of reducing the impedance of the drive loop in the process of crosstalk generation,a novel active Miller clamp gate drive design is proposed by adding PNP triodes connected in series with diodes and capacitors between the gate and source,and its working principle is analyzed.The parallel capacitance parameters of the improved drive circuit are also calculated and designed.Finally,an experimental platform of doublepulse test for a synchronous Buck converter with DC bus voltage of 300 V was built,and the novel crosstalk suppression drive circuit was compared with the traditional and typical crosstalk suppression circuits in terms of the positive and negative crosstalk voltage spike suppression effects and the turn-on and turn-off speeds.Experimental results show that compared with those of the traditional and typical crosstalk suppression circuits,the positive and negative voltage spikes of the proposed crosstalk suppression drive circuit were reduced by 80%and 40%,respectively,and the switching delay of the device was reduced by 32%in the meantime.