Soft-Switched High Step-Up DC-DC Converter with Coupled Inductor of Resonance

A soft-switched high step-up converter with coupled inductor is proposed in this paper. By replacing the output diode of conventional Boost converter with an active switch, zero-voltage-switched turn-on of power switches and zero-current-switched turn-off of diodes can be achieved, which reduce switching loss and alleviate reverse-recovery problem of diodes. Owing to the output-series of three units, the proposed converter can achieve high voltage gain without extreme high duty cycle and high voltage stress. Thus low-voltage-rated MOSFETs can be utilized to improve the efficiency. By designing the resonance between the leakage inductor of coupled inductor and multi-voltage capacitor, the current of switches can be decreased when they are turned off, which can reduce switching loss. The steady-state operating characteristics and the requirement of the ZVS of the proposed converter are analyzed in detail. Experimental results of a 160W prototype verify the theoretical analysis. © 2019, Electrical Technology Press Co. Ltd. All right reserved.