Design Of High Power Three-Phase Active Power Factor Correction System Based On DSP

With the development of power electronic technology,the widespread use of a variety of high power nonlinear power electronic devices and rectifier devices easily leads to a large number of harmonics into the power net,the input power factor of AC side power equipment power is reduced,the harmonic distortion of the input current is large,and power factor correction(Power Factor,Correction,PFC)system dynamic response and its effect is not ideal,which seriously affects the power net environment and reduces the power quality.Combined with the newly established harmonic limit standards and continuously improving industry indicators,the trend of digital development of industrial control is synchronized.The three-phase high-power active power factor correction technology based on DSP is a research hotspot in the field of power electronics technology.This thesis,which mainly focuses on the high power load,the dynamic response speed of active power factor correction system of power electronic equipment is not timely,and the power factor correction effect is not ideal,researches and improves the digital control method,which makes the power electronic equipment achieve ideal power factor correction effect at the high power load.Specifically,the contents of this thesis are as follows:Firstly,the research background,purpose,significance,development situation and concept of power factor are introduced.The trend and advantages of digital control of three-phase high-power active power factor correction technology are pointed out.Based on this,this thesis analyzes the three-phase four-wire six-switch Boost type APFC circuit operating principle,working mode,input current and input power factor calculation,SPWM duty cycle control signal generation principle,three-phase six-switch Boost type APFC circuit topology 24 working modes,summarizes and compares two types of control methods for three-phase Boost APFC technology,input boost inductor current interruption and continuous mode,and optimizes the control method of high-power three-phase APFC system.Secondly,the overall design of the digital control of the three-phase six switch high-power Boost APFC system is given in detail.The defects of the current high-power APFC digital method are compared and analyzed.The double closed loop APFC digital control method with voltage feedforward is proposed and the transfer function of the control system is calculated,meanwhile,and based on the system transfer function,the small signal control model of the three-phase power factor corrector was designed.Applying MATLAB/SIMULINK simulation software to verify and analyze the stability and abrupt changes of the AC input voltage when the system model is working,the experimental results show that the input voltage feed forward part can effectively improve the dynamic response speed of the high-power three-phase APFC system and improve the power factor correctioneffect.In addition,the hardware and software system of the three-phase active power factor corrector was designed,including the performance index of the three phase active power factor corrector,overall hardware system,and control circuit submodules of the three-phase active power factor corrector,the system main program software,interrupt service program software and task assignment are realized on the CCS3.3 software development platform.Finally,a prototype of a high-power three-phase active power factor correction system based on DSP was built.The test results indicate that the three-phase input voltage and current waveforms of the AC input side of the system follow the ideal,the three-phase input PF values were all greater than 0.999 and the three-phase input current THD Values were all less than 5%.The DC output voltage values of 370 V and 400 V for the DC output side with and without load,respectively.The test results except for the peak value of the DC output voltage are all ideal values,which basically reaches the expected design goals.