Control voltage of DC energy storage unit in universal power quality compensator based on ZVT-PWM

Supply power for DC energy storage unit by rectifier circuit produced harmonic and decreased power factor. Active power factor correction (APFC) resolved these problems, but this kind of hard switching circuit produced much consumption. It proposed a strategy that using soft switching power transformation technology to control switching devices. An improved scheme based on zero voltage transition (ZVT) PWM converter was presented and corresponding circuit was designed. The dynamic operation courses of circuit and switching states of power devices were researched. The strategy realized zero voltage transition by controlling power devices. Main switching device was conducted and turned off when voltage of resonance network was zero. The results have verified validity and feasibility of the strategy. It can decrease power consumption of switching devices, reduce harmonic, improve power factor and further perfect operation performance of universal power quality compensator.