Research On Control Strategy Of Dual-PWM High Frequency Power Supply

The electric equipment in many particular places such as bank computer rooms,hospitals,special process,communication stations,etc,have high requirements for the voltage quality of the power supply,which has a range of the best within 5 percent.However,the normal three-phase voltage,which would fluctuate because of impact load nearby,would drop because of long distance power transmission,and would have much harmonic because of the using of a lot of power electronic load,cannot satisfy the requirement.This thesis has a research on circuit topology,mathematics modeling,vector analysis,conversion of reference frame,phase-locked loop,the voltage and current control of PWM rectifier,output voltage of PWM inverter,aiming at the control strategy of dual-PWM three-phase AC power supply.Adopt double second order generalized integrator software phase-locked loop to realize precise phase locking in the harsh environment where voltage fluctuation and three-phase unbalance may occur.Apply a method to produce SVPWM based on unified voltage modulation rather than vector composing in order to reduce the consumption of CPU resource.Sampling the three-phase output voltage of the PWM inverter to achieve closed loop control so as to decrease the effect of dead time,switching voltage drops,filter voltage drops.Moreover,the voltage and current loop control of the PWM rectifier and the voltage feed-back control of the PWM inverter also be discussed.The system is simulated by matlab/Simulink platform,that gives a verification for the algorithm of several technical link such as phase-locked loop,PWM recitifier and PWM inverter.Finally,experiment is operated on low power experiment platform,which proves the feasible of the control strategy.