Deadbeat Direct Torque Control Of Permanent Magnet Synchronous Motor

With the growth of China’s social economy,the popularity of elevators has been increasing and elevators have become an indispensable part of people’s daily lives,especially in metropolis.The normal operation of elevators is closely related to the interests of many people and even personal safety.With the decrease in the price of permanent magnet materials and the development of power electronics technology,permanent magnet synchronous motors have been widely used in elevators.However,as an important part of elevators,the elevator door-motor system is still not perfect.There is serious torque ripple in traditional direct torque control system,which means that the demand of the the system’s stability can not be met,and the development of the elevator industry is seriously hampered.Therefore,this paper studies the torque ripple suppression of PMSM-DTC based on the deadbeat control algorithm.With the hidden pole permanent magnet synchronous motor as the research object,This paper established its mathematical model in the d-q rotating coordinate system and mainly studied the deadbeat direct torque control algorithm,to suppress motor torque ripple and optimize the performance of overall system.The main achievements are as follows:(1)Aiming at the problems existing in the traditional flux observer in PMSM-DTC,two improved flux observer based on the first-order inertial filter and the amplitude-limiting compensation integrator are proposed,whose principle is elaborated in detail.The model was built in simulink and its principle simulation was carried out.The results show that the flux observer based on the amplitude-limiting integrator performs better,and the stator flux can be accurately estimated in the full-speed operation range of the motor.It is of great reference value for the follow-up study of deadbeat direct torque control.(2)The deadbeat direct torque control strategy based on the hidden pole PMSM is adopted.Under the guidance of deadbeat control theory,the derivation of the voltage control law is completed,which can be used to design the deadbeat controller.Both traditional control strategy and the proposed control strategy are studied in simulation.The results show that in the deadbeat direct torque control strategy,torque and flux linkage ripple is reduced obviously,and the advantage of rapid torque dynamic response remains.So the feasibility and Superiority of the proposed strategy are verified by simulation results.(3)In the deadbeat direct torque control of permanent magnet synchronous motor,a traditional PI controller is used in the speed loop.Therefore,there is aphenomenon that the parameter is difficult to set,which increases the complexity of the system.To solve this problem,an improved control method based on back-stepping control algorithm is proposed.A novel speed-controller based on back-stepping control algorithm is designed to replace the PI controller.And the simulation results show that the improved scheme has excellent dynamic and static performance,which not only retains the ability of deadbeat direct torque control to suppress the torque and flux ripple effectively,improves the torque dynamic performance,reduces the sensitivity to stator resistance and inductance parameters,but also has the advantage of less adjustable parameters.The entire system has been simplified.