Peak Temperature Reduction Method of SiC-MOSFETs Employed in the Initial Charge for the DC Capacitor Using Leg Short-Circuits

Abstract

This paper proposes an improved initial-charge method for the de-capacitor in voltage source power converters. The proposed method makes multiple short-circuits in each leg by using power devices in the converter, which discharges the dc capacitor and suppresses its overvoltage due to the initial charge. Short time periods of short-circuit occur several times in each leg for reducing the power consumption in and peak junction temperature of power devices. The experimental verification using a 200-V, 5-kVA three-phase converter shows that the proposed method can reduce the power consumption by 6% and suppress the estimated peak temperature by 200 ° C. The experimental results exhibit a good overvoltage suppression capability of the proposed method without SiC-MOSFET degradation. As a result, the proposed method makes it possible to remove the initial charge circuit resulting in reduction in the size and cost of power converters.