PWM Rectifier System Design Based On Predictive Direct Power Control Algorithm

The development of society requires lots of energy,research about new energy area and how to improve the efficiency of energy use become more and more popular.Wind power and solar power generation transform other form energy to electric energy,it need technique of PWM rectifier.While the methods to improve energy utilization such as frequency control,phase control are also based on PWM rectifier technique.In such background,the paper chooses PWM rectifier control as the main research point.The traditional direct power control strategies have simple algorithm and quick response to power decoupling control.This paper built the modulation of direct power control strategy based on virtual flux,and deficiency is its fluctuate switching frequency make it hard to design filter.Virtual flux direct power control based on PI strategy overcome the frequency problem,but due to the fact that it is hard to choose PI parameters as well as its decline in respond,it's can't meet high demand.Predictive direct power control strategy can overcome the above deficiency.This article mainly discusses the PWM converter and its improved predictive direct power control strategy.Predictive direct power control strategy is an advanced method which can well apply to PWM converter.But it can not apply to the situation when current and active power is high while switching frequency is insufficient,the performance is not so precise in transient and steady state.The improved predictive direct power control strategy has two changes.First of all,the predictive model accurate algorithm by improve the estimation of the active power/reactive power and use newton interpolation to estimate the reference voltage.Secondly,the strategy add feedback correction section which eliminate the error between the predictive power value and true power value,it predict the next predictive power value as well.Through the above measures,not only increase the precision of the control algorithm,but also make it can be used in the situation that high power and low sampling frequency.The method is tested by simulation studies on a three phase PWM converter,using Matlab/Simulink.There are lots of contrast between the previous method and the new method.Obvious improvement can be found in results.Simulation results further verify the feasibility of the proposed control strategy...