Digital Active Power Factor Correction Technology Suitable For DCM Boost Converter And Its FPGA Implementation

Active power factor correction technology has been widely used worldwide as an important means to improve power factor and reduce harmonic pollution in electrical equipment.Boost PFC based on DCM mode has low cost and simple structure,so it is widely used in small and medium power scenarios.This paper is devoted to the research of digital active power factor correction technology based on Boost PFC in DCM mode.The author deduces and compares different digital control strategies,and conducts experimental verification based on FPGA digital control technology.In this paper,the different working mode of DCM Boost PFC is analyzed,and an experimental prototype with 85 ～ 265 V input voltage and 120 W output power is designed according to the experimental requirements.In the light of the principle of the traditional voltage loop control method,the expression of power factor is derived,and the relationship between the power factor and the voltage regulation ratio is revealed.In order to solve the defects in traditional voltage loop control,it is proposed to improve by adding a current inner loop.However,the voltage and current dual-loop control method requires an additional current sampling device,and has a problem of sampling delay.Therefore,based on the idea of analog control,this paper proposes an FPGA-based sensorless average current mode(SACM)digital control method to clarify the relationship between the required duty cycle and the input voltage along with the output voltage.Subsequently,the above derivation was simulated and verified based on MATLAB/ Simulink platform.This new digital control technology optimizes the power factor at high voltage regulation ratios,while avoiding the problem of current loop delay under dual-loop control,and effectively reduces current harmonics over a wide input range.This article also describes the implementation of the PFC control platform based on the Cyclone Ⅳ E series EP4CE22F17C6 development board。A digital control framework based on FPGA is constructed,and three different control methods are implemented on this basis.The experimental results show that the FPGA-based SACM digital control method performs single-cycle control at a frequency of 50 KHz.In the full range,the power factor can reach more than 0.995,the peak value is 0.9983,and the total harmonic distortion of the input current is less than 6.9%,which is significantly better than the other two control methods in a wide input range and the power range.Based on the same set of experimental platforms,the experiments also revealed the problems and disadvantages of traditional voltage loop control and dual-loop control.The results prove that the power factor correction effect of the proposed control method on DCM Boost PFC has significant advantages.