Basic Study of Dead-Timeless Control Technology for SiC-MOSFET Applying Current Detection Circuit Using Wiring Inductance of Semiconductor Device

Abstract

MOSFETs generally have excellent switching characteristics, and their switching losses can be reduced by synchronous rectification. Furthermore, using the body diode of MOSFET, it is possible to remove any external freewheeling diodes. However, the body diode of a SiC-MOSFET has two major problems: the on-state voltage of the body diode is high, and a reverse recovery current occurs. These problems are appeared by the current flowing through the body diode during the dead time of synchronous rectification. To prevent these problems, we propose a synchronous rectification scheme with substantial zero dead time control. In this type of control, we apply a circuit to detect current by integrating the voltage generated in the wiring inductance of the semiconductor device. A short-circuit current flows by substantially eliminating the dead time, but it is limited by providing a period of suppressed gate voltage. In this paper, we present the principle of this scheme, measurement results of the loss when the MOSFET is turned-on/off, and control parameters. Using this scheme, it was confirmed that the loss when the MOSFET is turned-on/off could be reduced.