Self-Oscillating Drive Circuit Using Cascode-Connected Normally-on Device and Normally-off Device for Self-Powered Active Bridges

Self-powered active bridges have the same number of external terminals as diode bridges, and they can improve the efficiency of conventional PFC boost rectifiers that come with a diode bridge for line rectification. However, bulk capacitors required for accumulating energy to drive rectification MOSFETs cause increase in the mounting area of drive circuits. This paper proposes a novel self-oscillating drive circuit, in which two pairs of cascode-connected a high-breakdown voltage normally-on device and a low-breakdown voltage normally-off device are used as the lower-arm rectification switches, to reduce the number of bulk capacitors. The operation of the proposed drive circuit was verified experimentally, and the efficiency of a 2.4 kW PFC boost rectifier that comes with the proposed drive circuit was measured.