Digital active gate drive of SiC MOSFETs for controlling switching behavior -- Preparation toward universal digitization of power switching

Abstract

In this paper, a digital active gate driver for SiC power MOSFETs is proposed. High-frequency switching with SiC power MOSFETs can realize an integrated power circuit with higher power density. However, the large surge voltage and ringing caused by the fast switching will lose the reliability of the device and increase electromagnetic interference (EMI) problems. To achieve high-frequency switching without these drawbacks, an active gate driver based on the architecture of a digital-to-analog converter has been designed. The gate-source voltage waveform of the MOSFET is generated directly and flexibly by a multibit gate signal sequence, considering the device characteristics and a variety of circuit conditions. Effective gate signal sequences are investigated by focusing on the switching trajectory on the state space of the device, which is discretely controlled through successive transitions between operating points. Experimental and simulated results confirm that the proposed gate driver effectively suppresses and regulates the surge voltage and ringing during turn-off.