Digital Control for Voltage Balancing under Switching Operations of Series Connection SiC-MOSFETs

Abstract

Recently, there has been research and development of SiC power devices, and 1,200V SiC-MOSFETs have become commercially available. SiC power devices are suitable for realizing higher voltage applications, and the power devices are connected in series for maintaining the voltage rating. However, the parasitic parameters of the devices are not the same, and it cannot be controlled the voltage sharing. This paper proposes a digital control method for the voltage balancing of series connection SiC-MOSFETs under turn-off operations. In order to compensate the voltage unbalance conditions, this paper presents a time-adjustment gate-drive circuit using an 8-bit programmable delay line. Its performance verified analytically, and experimental results using a buck chopper circuit rated at 1,200V SiC-MOSFETs are presented.