Amplified OFF State Voltage Stress across SiC MOSFETs of 4-Quadrant Switch

SiC MOSFET is a high-speed switching and a lowloss device preferred over Si IGBT in 4-quadrant switches for applications like AC-AC motor drives. These switches allow bidirectional current and block bipolar voltage. Circuit parasitics affect the converter’s performance in high-speed switching power electronic converters. Power electronic devices’ parasitic capacitances reduce the switching speed, causing more switching loss. Moreover, gate-driving circuitry is also required to drive MOSFETs and IGBTs. Parasitic inductances cause voltage overshoot and oscillations across the devices. These undesirable effects of circuit parasitics are well-reported in the literature. However, in case of a 4-quadrant switch, another undesirable effect of parasitics is shown in this paper, which is missing in the literature. Circuit parasitics also cause amplification of steady-state voltage during the OFF state of the devices of the 4 -quadrant switch. The amplified steady-state voltages cause increased switching times and loss, which are undesirable due to reduced efficiency and switching frequency. The paper explains the amplification of steady-state voltage during the OFF state of the devices of the 4 -quadrant switch with the help of theoretical analysis and experimental results.