A Dead-Time-Controlled Gate Driver Using Current-Sense FET Integrated in SiC MOSFET

Abstract

In comparison with silicon IGBT, silicon carbide (SiC) MOSFET is expected to reduce the switching loss and the conduction loss and to remove external freewheeling diodes (FWDs). However, its body diode has comparatively high forward voltage; therefore, the diode conduction loss generated during dead time increases. As a result, the loss reduction by the use of the SiC MOSFET can be weakened. This paper proposes a simple dead-time controller integrated in an isolated gate driver in order to reduce the diode conduction loss during the dead time. The proposed method has high speed and high robustness against switching noise by using of a current-sense FET with small parasitic capacitance. As a result, the diode conduction time can be shortened within 0.1 μs. In addition, the proposed dead-time control method can be achieved by existing components, including the current-sense FET, which is currently used for short-circuit current detection in hybrid vehicle applications. The proposed method was applied to a 10 kW boost converter with SiC MOSFET. The experimental results showed 1% higher efficiency of the converter with the proposed dead-time-controlled gate driver compared to that without dead-time control circuit, and the efficiency was the similar level as when a SiC Schottky barrier diode (SBD) was used as FWDs.