Study Of Asynchronous Motor Speed Regulation System Based On MPC

As people pay more and more attention to energy crisis and environmental protection,energy saving and emission reduction has become an effective way to protect the natural environment and face the energy crisis effectively in electric drive system.Asynchronous motor with double PWM variable frequency speed regulation system is the key technology in electric drive system,therefore,The research of high performance variable frequency speed regulation technology is of great significance to improve the efficiency of electric drive system and save energy.Based on this,this paper studies double PWM variable frequency speed regulation system of three-phase asynchronous motor based on MPC,and the main content of the specific research methods are as follows:(1)The three-phase voltage source PWM rectifier is chosen as the grid side converter.First of all,based on a brief analysis of three-phase voltage type PWM rectifier on the mathematical model,grid side rectifier voltage and current double closed-loop control strategy is studied;at the same time,in order to choose the better method to generate PWM wave,a comparative analysis of SPWM and SVPWM two kinds of modulation method of PWM wave.Then,in order to make the DC side of the converter have a better response speed to the load change,the current compensation circuit is adopted in the current loop.Fina lly,the simulation results show that the control performance of SVPWM rectifier is better to the rectifier based on SPWM;at the same time,voltage and current double closed-loop control based on current compensation has better response speed and stabilizing voltage effect for the change of load.(2)Vector control strategy of inverter based on MPC is studied.Firstly,the paper analyzes the mathematical model and the FOC-VC strategy easily.Then the vector control of induction motor based on MPC is studied in detail;at the same time,aiming at the existing MPC calculation is large and complex,resulting in model predictive optimal control algorithm of low precision and large hardware consumption,after the equivalent transformation of the value function,this paper presents two kinds of improved model predictive control scheme:(a)scheme one,firstly the space vector plane is divided into 6 regions by base the angular bisector of the voltage vector,the reference voltage forecast value and the concept of the region where the reference voltage are obtained by the deadbeat control theory and longitudinal compression transform.Finally the optimal voltage vector and the optimal switching sequence is obtained by logical judgment;(b)scheme two,deadbeat theory and transverse compression transform theory are drawed to obtain a prediction reference voltage and the sector,The vector on the dividing of the regional new coordinates is transformed by the longitudinal compression,which can exactly judge the reference voltage and determine the optimal switching sequence.The two improved MPC scheme not only reduces the computational complexity and complexity of the control algorithm,but also ensures a good speed regulation performance and better electromagnetic tracking effect.(3)Build AC-DC-AC variable frequency speed control system model which a grid side PWM rectifier with the three-phase AC power supply and machine side voltage type PWM inverter with three-phase induction motor,the feasibility of the theory is verified to applied to the system.