Research On Model Predictive Direct Power Control For Three-phase Voltage-type PWM Rectifiers

With the development of science and technology,power electronics converter device is becoming wider in all fields.Traditional converter device usually use diode rectifier,its configuration is simple,low cost,but it contains a large number of low order harmonics and cause serious harmonic pollution to power grid.Based on the shortage of diode rectifier,PWM rectifier have some advantages,including energy bi-directional flow,controllable input power factor,low harmonic of grid side and adjustable dc voltage,make it get widely used in many converter device.This paper take three-phase voltage source PWM rectifier as the research object,and have a discussion about model predictive direct power control strategy.Firstly,according to the principle of three-phase voltage source PWM rectifier built its mathematical model of three-phase static coordinate system,two-phase static coordinate system and two-phase rotating coordinate system and the calculation method of instantaneous power,respectively.In addition,there have introduced principle and simulation experiment on voltage oriented vector control,direct power control based on switching table and direct power control based on space vector modulation.Secondly,consideration the deficiency of three kinds of commonly control strategies for three-phase voltage source PWM rectifier,conbining the principle of model predictive control,proposed the research on model predictive direct power control for three-phase voltage source PWM rectifier.There are one problems in model predictive direct power control that it cannot accurately track the power,therefore this paper introduced repetitive control to improve the control system,proposed the improved model predictive direct power control.According to the simulation results,it verified the improved model predictive direct power control have successfully realized the power of astatic tracking.Thirdly,to leave out the ac voltage sensors of control system,and save the hardware cost and improve the reliability of control system,combining flux observer with saturable feedback loop,proposed the improved model predictive direct power control based on virtual flux,and do some research on the robustness of the control strategy.Through the simulation verify the correctness and feasibility of this control strategy.Finally,according to the simulation model is set up corresponding experimental platform,design a part of the hardware and software,the experimental results verify the feasibility of this control strategy.