A Novel active voltage clamping circuit topology for series-connection of sic-mosfets

Series-connection of silicon carbide (SiC)-MOSFETs is an attractive method to achieve a high-voltage and fast-switching power semiconductor switch. In order to deal with the unequal voltage sharing problem in such series connection method, a novel active voltage clamping circuit topology is proposed in this letter. The maximum drain source voltages of the series-connected SiC-MOSFETs are clamped by individual clamping capacitors; therefore, high reliable switching of the power semiconductors is guaranteed. Besides, the accumulated energy in the clamping capacitors can be actively transferred back into the power supply through a simple gate drive signal adjustment algorithm; thus, the induced clamping circuit loss can be effectively suppressed. The proposed active clamping topology has been experimentally verified in a half-bridge inverter with four SiC-MOSFETs connected in series.