A Single-Stage Isolated Charging/Discharging DC-AC Converter With Second Harmonic Current Suppression in Distributed Generation Systems

摘要

In this paper, the circuit topology of single-stage isolated charging/discharging DC-AC converter with second harmonic current suppression is proposed. Based on which an analogous-rectifying unipolar phase-shifted control strategy with constant charging/discharging current is also proposed, which rectifies the Sinusoidal Pulse Width and Position Modulation (SPWPM) wave of high-frequency (HF) transformer to positive/negative half line cycle Sinusoidal Pulse Width Modulation (SPWM) wave through the bi-directional rectification circuit, and realizes constant charging/discharging current of the battery at the same time. Aiming to suppress the input second harmonic current, an L_r-C_r parallel-resonant circuit which is connected in series between the battery and input filter capacitor is introduced. Experimental results of the designed prototype show that the proposed converter has excellent performances such as HF galvanic isolation, single-stage bi-directional charge/discharge, high conversion efficiency and small ripple of input current, which provides a new methodology for battery charge/discharge in distributed generation systems.