Reduction of Switching Loss and Input Voltage/Current Ripples of DC-DC converter for Photovoltaic Systems

Abstract

This dissertation describes a boost half-bridge DC-DC converter that reduces the input voltage and current ripples by using a 1:1 transformer and an auxiliary capacitor. The 1:1 transformer replaces the boost inductor of a previous boost half-bridge converter. The auxiliary capacitor is connected in series with the secondary coil of the 1:1 transformer and resonates with the leakage inductance of the 1:1 transformer. Then, the input voltage and current ripples are reduced by setting the switching frequency equal to the resonance frequency between the auxiliary capacitor and the leakage inductance, and by coupling the resonance current to the primary coil of the 1:1 transformer. In addition, a storage capacitor of the proposed converter reduces the peak voltages of switches by reducing the voltage ripples of switches, thereby reducing the switching loss of switch. Compared to the previous converter, the proposed converter has higher power-conversion efficiency and lower input voltage and current ripples, which increase the efficiency of electric power generation of photovoltaic systems.