Sensorless Control System Of Permanent Magnet Synchronous Motor With Double Sliding Mode

Permanent magnet synchronous motors(PMSM)are widely used in electric vehicles,metro transport and household appliances due to their small size,high efficiency and high power factor.In this thesis,the dynamic response time,jitter and estimation accuracy of the PMSM control system are investigated by improving the sliding mode controller and sliding mode observer.Firstly,based on the coordinate transformation rule,the control strategy with i_d=0is selected and the SVPWM modulation method is used to establish the PMSM vector control system.To address the problems of slow convergence and discontinuous switching functions of the sliding mode control algorithm,a composite convergence law combining a variable power convergence law and a continuous segmented exponential function is designed,and the advantages of the composite convergence law in terms of convergence time and smoothness of the convergence response curve are verified by using the analytical method and simulation comparison analysis.Secondly,to address the problem that PI controllers are susceptible to changes in system parameters and slow to respond to sudden changes in operating conditions,an improved sliding mode controller(ISMC)is designed based on a mathematical model in the PMSM two-phase rotating coordinate system,using the advantage that the integral sliding mode surface can weaken the steady-state error of the system,and combining the composite convergence law with the integral sliding mode surface.The ISMC algorithm is compared with the PI algorithm through simulation,and it is demonstrated that the introduction of the ISMC algorithm can speed up the dynamic response of the system,reduce the amount of overshoot and enhance the anti-interference capability.Thirdly,to address the problems of low observation accuracy and long convergence time of the traditional sliding mode observer(SMO),a non-singular fast terminal sliding mode surface is proposed and verified to be able to converge quickly by the analytical method;together with the composite convergence law,a non-singular fast terminal sliding mode observer(NFTSMO)is designed.The SMO is combined with the ISMC to form a double sliding mode control(DSMC)algorithm,and the NFTSMO is combined with the ISMC to form an improved double sliding mode control(IDSMC)algorithm.Simulations are also carried out to compare the two algorithms.The results show that the IDSMC algorithm can make the estimated motor speed and rotor position closer to the actual values,significantly weaken the system jitter,rapidly converge the system state error,and improve the dynamic performance when the system operation state changes.Finally,using TMS320F28335 as the core,the hardware circuit is designed and the algorithm program is written to build an experimental platform for the PMSM sensorless control system,and the experimental analysis is carried out for different operating conditions.The results show that the IDSMC algorithm can improve the estimation accuracy,accelerate the dynamic response time and reduce the system jitter.The experimental results are consistent with the simulation results,further verifying the feasibility and correctness of the proposed algorithm.