Research On Sensorless Control Of Permanent Magnet Synchronous Motor Based On Disturbance Compensation

With the advantages of simple structure,small size,light weight,lower loss and higher efficiency,Permanent Magnet Synchronous Motor(PMSM)is widely used in home appliances,medical,transportation,aerospace and other fields.As the most widely used control method for Permanent Magnet Synchronous Motor,Field-Oriented Control(FOC)can achieve high control accuracy and wide speed range.However,this control method requires accurate information about the positon of the motor rotor,which is usually obtained using mechanical sensors such as hall sensors and photoelectric encoders,but it also brings many disadvantages,such as inconvenient installation,susceptibility to interference in specific operating environments,and increased costs.Therefore,the research of sensorless technology has important practical significance.Meanwhile,in the sensorless control system of permanent magnet synchronous motor,the change of load torque will have a large impact on the control system,and it is especially important to reduce the impact of load torque disturbance on the control system.The specific work of this paper mainly includes the following aspects:(1)The mathematical model of PMSM and Field-Oriented Control technology are introduced.In order to improve the motor dynamic performance and system robustness,the sliding mode control method is selected instead of the traditional PI control.The basic principle of sliding-mode variable structure control is described,and the causes of jitter generated by sliding-mode variable structure control and the methods of suppression are analyzed.A sliding mode speed controller based on the improved exponential convergence rate is designed,and the simulation model is built in MATLAB/Simulink platform for analysis and verification.(2)Based on the principle of sliding-mode variable structure control,a PMSM sensorless control model using the traditional sliding mode observer is built.For its low estimation accuracy and serious jitter phenomenon,the traditional sliding mode observer is improved by using the quasi-sliding mode method,and an adaptive sliding mode observer based on a new saturation function is designed.A PMSM zero-speed starting method is proposed to solve the problem of large observation error of the observer at the early stage of motor starting.Finally,a simulation model is built in MATLAB/Simulink platform to verify that the designed new sliding mode observer can effectively weaken the jitter and make the system have better dynamic performance.(3)In order to observe the variation of load perturbation of PMSM,two conventional observers are first designed to observe the load torque.Then,based on the Super-Twisting algorithm,a modified third-order super spiral sliding mode observer is designed to observe the load torque and compensate the current loop with the observed load torque.Finally,a simulation model is built in MATLAB/Simulink platform to verify that the designed improved third-order Super-Twisting sliding mode observer has better speed and stability.(4)The experimental platform of PMSM was built with Digital Signal Processor(DSP)as the core,and the related software and hardware design was completed.The correctness and feasibility of the designed speed sensorless control algorithm and load torque observer are verified by experiments.