Development of converter cooperative control for buck-boost mode multi-level AC/DC converter

A new control method for multi-level PFC converters is proposed in this paper. Multi-level AC/DC comprises a PFC reactor, sub converter, and main converter. With cooperative control, the sub converter and the main converter switch each other, and they cooperate to control input current and output voltage. The proposed control can reduce the capacity of the sub converter capacitor to 1/200 of the conventional control. As a result, high power factor and constant voltage controls in the buck-boost modes are verified experimentally with a 3-kW prototype using film capacitors. Moreover, the same efficiency as that of a conventional one is achieved. © 2019 The Institute of Electrical Engineers of Japan.