桥式电路中不同封装SiC MOSFET串扰问题分析及低栅极关断阻抗的驱动电路

由于SiC MOSFET开关速度较快,使得桥式电路中串扰问题更加严重,这样不仅限制了SiC MOSFET开关速度的提升,也会降低电力电子装置的可靠性。针对SiC MOSFET的非开尔文结构封装和开尔文结构封装的串扰问题分别进行分析,栅漏极结电容的充放电电流和共源寄生电感电压均会引起处于关断状态开关管的栅源极电压变化。提出一种用于抑制串扰问题的驱动电路,该驱动电路具有栅极关断阻抗低、结构简单、易于控制的特点。分析该驱动电路的工作原理,提供主要参数的计算方法。最后通过实验测试了两种结构封装SiC MOSFET的串扰问题,并且对提出的驱动电路进行了实验,验证了其正确性以及对串扰问题的抑制效果。

Analysis for Crosstalk of SiC MOSFET with Different Packages in a Phase-Leg Configuration and a Low Gate Turn-Off Impedance Driver

Because of higher switching speed of SiC MOSFET, crosstalk in a phase-leg configuration will be more serious. It will hinder the increase of switching frequency and reduce the reliability of power electronic equipment. This paper analyzes the crosstalk mechanisms of non-Kelvin package and Kelvin package, respectively. During the turn-on transition and turn-off transition of a switch, the displacement current of the gate-drain capacitor and the drop voltages on the common source inductors can induce the gate-source voltage variation of the off-state switch. Then, this paper proposes a new gate driver for suppressing crosstalk, which creates the low turn-off gate impedance. The operating principle and the parameters design are also analyzed. Finally, the crosstalk problems in non-Kelvin package and Kelvin package are tested by experiments. The experimental results of the proposed driver prove the effect of crosstalk suppression.