Simulation Study On The Decoupling Control Of Permanent Magnet Synchronous Motor

The Permanent Magnet Synchronous Motor(PMSM)is a type of electric machine which has stator like an induction motor and the rotor with permanent magnets.In PMSM,air gap magnetic flux is generated by using the permanent magnet placed on the rotor.This structure makes the PMSMs possible to reach higher efficiency than the traditional induction motor.Moreover,PMSM has many key features,such as high reliability,low EMI,high transient performance,sensorless speed control possible,smooth rotation without torque ripple,appropriate for position control.At present,as for the PMSMs,the most popular control strategy is the field oriented control algorithm.In control algorithm,with the coordinate transformation theory,the mathematical model of the PMSM in three-phase static coordinate system can be transformed to the mathematical model in dq axis rotating coordinate system,and this will greatly simplifying the complexity of the motor's model.On this basis,by using the PI controller(Proportional Integral Controller,PI Controller),the rotor flux and electromagnetic torque can be controlled respectively.Traditional field oriented control algorithm uses the differential equations about the flux and voltage in dq rotating coordinate system as a mathematical model.With the addition of the PI controller,the entire control strategy can be designed and realized with simple control structure and high accuracy steady-state operating conditions.However,due to the mathematical model of PMSMs inherent coupling structure,while PI controller cannot decouple the mathematical model,the transient performance of the traditional control algorithms will be affected,and the tuning process of the controller's parameters will be complicated.In this paper,the traditional field-oriented control algorithms based on PI controllers is improved by adding the control structure of the cross-decoupling algorithm.The corresponding analyzes and studies of the impact of cross-decoupling algorithm on PMSM control system are taken.On this basis,with the simulation environment MATLAB / SIMULINK,the simulation model of the PMSM control system is built.Simulation results show that,compared to the traditional PI control strategy,the cross decoupling algorithm for PMSM control system has a faster response speed of the dq-axis currents,while the algorithm is simple and easy to implement.In the simulation of the load mutation,the electromagnetic torque and motor speed dynamic adjustment time is also significantly reduced.