Research On Passive PFC Converter With Wide Input Voltage Range

With the rapid development of switching power supply,people generally require to improve power quality and reduce the harmonic pollution of equipment to the power grid.Power factor correction(PFC)is widely used in switching power converters.Compared with active power factor correction converter,passive power factor correction converter has the advantages of simple structure and low circuit cost,but it generally has the problems of low power factor and narrow working range.Among them,the current source charge pump(CSCP)resonant PFC converter not only has the advantages of low cost and simple control,but also solves the low pf problem of passive power factor correction converter.However,its narrow operating range limits the application of this passive PFC converter.Firstly,this paper analyzes the working state of the traditional CS-CP resonant PFC converter,deduces the conditions for the CS-CP resonant PFC converter to realize the PFC function,and points out the reasons for limiting the working range of the converter: the high PF value cannot be realized in a wide range,the bus voltage is too high at high voltage input,and the circuit gain is insufficient at low voltage input.A variable turn ratio CS-CP resonant PFC converter is proposed.By adding switching devices on the secondary side of the transformer,the transformation ratio of the transformer is adjusted when the input voltage changes,so that the circuit can realize the PFC function.The relationship between the turn ratio and the realization of PFC function of the converter is deduced,the parameter design of the converter is analyzed,the different transformation ratios of the converter are determined,and the circuit is verified by the simulation software.At the same time,a 40 W principle prototype is made.The experimental results show that the variable turn ratio CS-CP resonant PFC converter can work in the range of 100～242VAC input voltage and has a high PF value.A variable turn ratio CS-CP resonant PFC converter is proposed.By adding switching devices on the secondary side of the transformer,the transformation ratio of the transformer is adjusted when the input voltage changes,so that the circuit can realize the PFC function.The relationship between the turn ratio and the realization of PFC function of the converter is deduced,the parameter design of the converter is analyzed,the different transformation ratios of the converter are determined,and the circuit is verified by the simulation software.At the same time,a 40 W principle prototype is made.The experimental results show that the variable turn ratio CS-CP resonant PFC converter can work in the range of 100～242VAC input voltage and has a high PF value.