Series Capacitance Gate Driver to Suppress Voltage Oscillation of SiC MOSFET

Abstract

The severe voltage oscillation of SiC MOSFET in switching transient affects the safety of devices and EMI. In this article, a series capacitance gate driver (SCGD) is proposed to solve this problem. The series capacitance is charged or discharged in switching transient so that the equivalent driving resistance is gradually increased compared with that of conventional gate driver (CGD), and the voltage oscillation is suppressed. Under the same voltage oscillation level, the average equivalent driving resistance of SCGD is smaller than that of CGD through reasonable parameters design. This means that the optimization of both voltage oscillation and switching loss is realized. Although active gate driver (AGD) has good performance in this respect, the effect may be affected by the delay and control accuracy due to very short switching transient time of SiC MOSFET. Compared with AGD, the proposed SCGD only adds passive components without any control and has a simple structure. The experimental results verify the effectiveness of SCGD.

Keywords

• voltage oscillation
• safety and EMI
• switching loss