A ZVT Auxiliary Circuit for High Step-Up Multi-Input Converters with Diode-Capacitor Multiplier

Abstract

In this paper, a Zero-Voltage Transition (ZVT) non-isolated high step-up multi-input DC-DC converters is proposed which employs an auxiliary cell and diode-capacitor multiplier. The auxiliary cell has only one switch and is suitable for high step converters with diode-capacitor multiplier. In the proposed converter, all semiconductor devices operate under fully soft switching condition. The main switches turn on and turn off under Zero Voltage Switching (ZVS) condition whereas the auxiliary switch turns on under Zero Current Switching (ZCS) condition and turns off under zero Voltage and Zero Current Switching (ZVZCS) condition. Also, ZCS condition at turn-off is provided for all diodes to eliminate reverse recovery issue. The structure of the proposed converter includes two boost cells, one diode-capacitor multiplier cell, and one ZVT auxiliary circuit. Soft switching conditions for all main switches are provided by only one auxiliary circuit. The proposed converter has high step-up conversion gain without any coupled inductor. Soft switching conditions, continuous current of input sources, high efficiency, expansion capability of input sources, returning the energy of the auxiliary circuit to the diode-capacitor multiplier and low-voltage stress on switches are the main advantages of the proposed converter. The steady-state analysis of the converter and operation modes are discussed. A 160-W prototype of the proposed converter is designed and implemented. Experimental results confirm that the theoretical and the efficiency of the proposed converter reaches 96.4% at the nominal load.