Research And Design Of Digital Boost PFC Bridgeless Converter

Switching power supplies dominate the power supply field with their high efficiency and high power density.The switching power supply contains nonlinear components,which generate a large amount of harmonic current and reactive power in the power grid to cause pollution to the power grid.Since Power Factor Correction(PFC)technology has good correction effects,PFC technology has become an important method to solve harmonic currents.As the power increases,the power loss on the rectifier bridge will not be underestimated,which limits its efficiency.In response to this problem,this paper proposes a bridgeless PFC circuit using digital control.This paper first analyzes the EMI(Electromagnetic Interference)and current detection problems faced by basic bridgeless topologies.With the in-depth study of scholars,the bridgeless dual-diode bridgeless topology developed from the basic bridgeless topology has alleviated the basic bridgeless EMI problem to some extent,but the problem of complex current detection has not been solved.In this paper,an improved double-diode bridgeless topology is presented,which has the advantages of simple current detection and small EMI.The traditional digital algorithm is directly converted from the analog control strategy,and the analog control strategy directly samples the input voltage as the current loop reference,which may introduce the noise signal into the current loop,which leads to control error.For this reason,the current is in the current.The loop is given and optimized,and a digital control strategy based on phase-locked loop is designed.A simple phase-locked loop based on zero-crossing detection is designed for input voltage.The current loop reference is provided by the phase-locked loop and voltage loop product,thus avoiding problems caused by input voltage noise and grid fluctuations.In this paper,the component selection and hardware circuit design of the bridgeless PFC converter designed in this paper are described in detail.In this design,the control chip and the driver chip need to be powered.Therefore,a DC 12 V single-ended flyback power supply is designed as an auxiliary power source.The system is modeled by the state space averaging method.On this basis,the double closed loop design is carried out.The simulation model of 500 W improved double diode tube bridgeless topology was established by Matlab/Simulink,and the simulation research was carried out.Finally,a 500 W prototype was designed and verified by experiments.Both simulation and experimental results demonstrate the effectiveness of the control strategy.