A new soft-switching technique for buck, boost, and buck-boost converters

A new soft-switching technique for buck, boost, and buck-boost converters using coupled inductors is proposed in this paper. The principles of operation of these converters are analyzed in detail. An additional winding is added on the same core of the main inductor for the purpose of commutation. By using hysteresis current control, zero-voltage switching conditions are ensured over a wide load range. The main inductor current is kept in continuous conduction mode with small ripple, which allows high output power and small filter parameters. Also, the switching frequency can be kept constant when the load changes. Prototypes of buck, boost, and buck-boost converters have been built to verify the proposed concept. The experimental results are presented and they verify the analysis.