Research On PID-type Iterative Learning Control For Permanent Magnet Synchronous Servo System

Permanent magnet synchronous motor(PMSM)is a nonlinear and strongly coupled multivariable system.PMSM is the control object of permanent magnet synchronous servo system,in order to achieve high-speed and high-precision control of the servo system,higher control methods are required.In this paper,the speed and position PID control strategy of permanent magnet synchronous servo system is studied based on iterative learning control.Firstly,the control structure of PMSM servo system is introduced.According to the coordinate transformation theory,the mathematical model and state space model of PMSM dq rotation coordinate system are established.Then it analyzes the the reasons for the periodic speed fluctuations and introduces the id=0 vector control method and voltage space vector pulse width modulation(SVPWM)technology.Then,the principle and application conditions of iterative learning control are described and PID-type iterative learning control algorithm is studied.Cogging torque,flux harmonics and other factors cause speed fluctuated largely.PI controller in parallel with P-type iterative learning controller to form a compound control to reduce the steady speed fluctuation in the speed loop.To improve the position tracking accuracy of the permanent magnet synchronous servo system,the position loop adopts P controller in parallel with PD-type iterative learning controller to form a compound control.Iterative learning control improves the position tracking accuracy in repeated operation of the system.As for the design of iterative learning controller,P-type iterative learning controller is used in the speed loop.According to the mechanical equation of PMSM and the convergence condition of iterative learning control.The learning gain is determined.The frequency domain method is used to analyze convergence condition.In the design of position loop control,the iterative learning convergence condition is derived in the frequency domain.According to the bode diagram,convergence conditions is verified.The Satisfy convergence of the frequency band is analyzed to determine the learning gain.The simulation models of two closed-loop speed control and three closed-loop position control are builted on Matlab.In the simulation,the performance of the iterative learning controller is verified.Finally,related iterative learning control experiments of PMSM servo system are completed on the experimental platform.Compared with the PI speed controller,the P-type iterative learning controller is added into the two closed-loop speed control experiment,which reduces speed fluctuation.Compared with the P controller,the PD-type iterative learning controller is added into the position control experiment of the three closed-loop servo system,which improves the position tracking accuracy.