Research On Position Sensorless Hybrid Control Of PMSM In Full Speed Range

High performance vector control speed regulation system requires accurate rotor speed and position information.The traditional motor speed and position information are mainly obtained by mechanical sensors.The use of these mechanical sensors will increase the cost of the speed control system,occupy a certain space and be easily interfered by external factors.Therefore,the position sensorless technology has become a hot research topic in the field of motor speed regulation in recent years.In the full speed range,there is currently no single and mature position sensorless control strategy to accurately estimate rotor speed and position information of permanent magnet synchronous motors.Under this background,the sensorless vector control of permanent magnet synchronous motor in full speed range is studied in this academic dissertation.In the low speed range,aiming at the problem of bandwidth reduction caused by the use of filters in the acquisition of high frequency and fundamental current by traditional pulse high frequency voltage injection method,an improved high frequency square wave voltage injection sensorless control strategy is proposed.The control strategy uses mathematical operations to separate the fundamental and high frequency current signals,avoiding the use of filters in the process of acquiring fundamental and high frequency current.The acquisition process of the rotor position error signal of the proposed sensorless control strategy is deduced.Luenberger observer is used to estimate the rotor speed and position information.The simulation results show that the control strategy can obtain the rotor speed and position information of the permanent magnet synchronous motor more accurately than the traditional position sensorless control strategy and has good dynamic performance.In the range of medium and high speed,the state model of error system is established based on the principle of MRAS.On the premise of satisfying the stability of the system,the linear compensator matrix for salient pole permanent magnet synchronous motor is given,and the strict positive real property of the linear forward channel transfer function is proved.The adaptive law is designed based on the Popov super stability theorem,and the rotor speed and position estimation process of permanent magnet synchronous motor is deduced.The simulation results show that the rotor speed and position of PMSM can be accurately estimated in the middle and high speed range,but there is still a big error between the estimated speed and position and the actual value in the low speed range.To solve this problem,a new sensorless hybrid control strategy is proposed,which combines improved high frequency square wave voltage injection for low-speed and model reference adaptive control for medium and high-speed sensorless vector control strategies.In order to ensure the smooth transition between the two sensorless strategies in the switching interval,a weighted transition strategy with variable weights is proposed.Through simulation and comparison,it is verified that the proposed hybrid control strategy has better rotor position and speed estimation ability in the full speed range.