Research On High Power Factor High Efficiency Interleaved DCM Boost PFC Converter

With the development of power electronic technology,power electronic equipment such as AC-DC converters is widely used.A large number of non-linear loads distort the grid-side current and cause current harmonic pollution.Active power factor correction(APFC)technology can reduce the total harmonic distortion(THD)of the grid-side current,improve the grid-side power factor(PF),and solve the problem of harmonic pollution.Among many PFC converters,the inductance of Boost PFC converter is connected in series at the input end,which has a significant effect on suppressing the high-order current harmonics.However,with the increase in the power level and power density of PFC converters,single-channel Boost PFC converters have been unable to meet the needs of use.To solve this problem,this paper studies a multi-channel interleaved DCM Boost PFC converter with high power factor and high efficiency.In this paper,based on the analysis of the working principle and operating characteristics of the multi-channel interleaved DCM Boost converter,the time averaging equivalent circuit modeling method is used to establish the time averaging equivalent circuit model of the multi-channel interleaved DCM Boost converter.The character of DC steady state is analyzed by the time averaging equivalent circuit model,the relationship between the inductance value and its equivalent series resistance(ESR)of the converter and the current sharing between channels is further studied and verified by simulation.The inductance value of each channel of the DCM Boost converter affects the current sharing between channels,that is,the better the consistency of the inductance of each channel,the better the current distribution effect between channels.Based on the constant duty cycle control technology of the traditional DCM Boost PFC converter,this paper discusses the constant duty cycle control principle of the multi-channel interleaved DCM Boost PFC converter,and analyzes the factors that affect the power factor and cause the input current distortion.In response to this problem,based on the constant duty cycle control,the formula of the number of interleaved parallel channels and the duty cycle change function are derived,the relationship between the number of interleaved parallel channels and the duty cycle is revealed.The variable duty cycle control technology of the multi-channel interleaved DCM Boost PFC converter is studied,and the advantages of variable duty cycle control are pointed out.The variable duty cycle control improves the power factor,reduces the peak value of the inductor current,and reduces the output voltage double-line-frequency ripple compared with constant duty cycle control.This paper analyzes the voltage stress and current stress of power devices with variable duty cycle control of multi-channel interleaved DCM Boost PFC converter,the design criteria of PFC inductor and output capacitor are derived in detail.The losses of each part of power devices and passive devices are analyzed in detail,and a loss calculation model is formed.Based on the loss calculation model,by analyzing the relationship between the number of interleaved parallel channels and converter losses,an improved variable duty cycle control technique to improve the efficiency of multi-channel interleaved DCM Boost PFC converter is studied.The improved variable duty cycle control improves the efficiency of the converter and can achieve a higher power factor compared with constant duty cycle control.Finally,according to the voltage and current stress analysis results of the power device,and the design criteria of the PFC inductor and output capacitor,the circuit parameters and device selection were determined,and an 800 W experimental prototype is built.The experiment verified the correctness of the theory analysis.