Research On A Zero-Current Soft Switching For PFC Converter

With the development of electronic technology, more and more power electronic equipment are widely applied to the grid system. It brings convenience to people, but also leads to low power factor and harmonic interference problem. Meanwhile, with the increasing power level, the power loss of the switching device is increasing. Therefore, higher power factor, lower switching loss and higher capacity have gradually become the focus of the study in the power electronics industry. A 1kW power factor correction circuit prototype is implemented,which implements zero-current soft switching and reduces power dissipation.The power factor of the input side is close to 1.In this paper, the present situation of soft switching power factor correction circuit across the world is discussed. Then various kinds of main circuit topology are shown and their advantages and disadvantages are also proposed. Then, with the combination of main and auxiliary switch, the boost circuit is chosen as the main circuit topology, applying the average current control scheme.This paper describes in detail the operating principle of the zero current soft switching PFC circuit and the various stages of L,C resonant circuit during the resonant process, and then analyzes the waveform of the key points and the formation principle of zero current switching, and then presents the time requirements and design ideas of the main, auxiliary switch trigger signal.Based on the design parameters of each device in the main and auxiliary switch circuit,the appropriate device are selected for making prototype. Applying the UC3854 chip, the inner and outer loops are designed and the appropriate L,C resonant circuit parameters are selected to build the experimental platform.The results verify that the main switch effectively realizes turning off at the zero current condition, greatly reducing the switch losses and improving power transmission efficiency of the entire circuit. Meanwhile, the main circuit maintains a constant output voltage, and at the input side the voltage and current are in phase, so its power factor is close to 1. Experimental work is included to verify the analysis.