Research Of Bridgeless PFC Converter

The bridgeless PFC converters have attracted attentions of people with its high efficiency and simple structure.But big electrolytic capacitors are usually needed to reduce the output voltage ripple in traditional bridgeless PFC converters,which increases the volume and decreases the reliability of the converter.The research related to bridgeless PFC converter was carried out to solve that problem.Firstly,the research status of the bridgeless PFC converter was introduced and the research status of power decoupling technology was summarized.The symmetrical half-bridge active power decoupling circuit was used to the bridgeless PFC converter with two diodes and the topology structure of bridgeless PFC converter with power decoupling was proposed.Besides,the operating principles of the bridgeless PFC converter with two diodes and the symmetrical half-bridge active power decoupling circuit were analyzed in detail.On the basis of that,the mathematical model of the bridgeless PFC converter with two diodes was built with the small signal analysis method.The double closed-loop control system was designed with the frequency-domain method.The modeling process of the symmetrical half-bridge active power decoupling circuit was introduced in this paper.The symmetrical half-bridge active power decoupling circuit can't function properly when the frequency of the input voltage of the converter is under fluctuation.A control strategy with PLL of the symmetrical half-bridge active power decoupling circuit was proposed in this paper to solve that problem.Finally,the theoretical analysis of the bridgeless PFC converter with power decoupling was proved by the simulation in PSIM.An experimental platform with the rated power of lkW was designed and built to provide experimental verification.The advantage of active power decoupling technology and the validity of the control strategy proposed were proved by the simulation and experimental results.