Research On Sensorless Control Technology Of Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)has a wide range of applications in many high-performance AC drive fields due to its high power density,high power factor,wide speed range and fast dynamic response.High-performance control methods for PMSM require more accurate rotor position information.Nowadays,because of the limitations of traditional mechanical encoders,accurate and efficient position sensorless control methods have become a hot topic in the field.In this paper,PMSM position sensorless control method is taken as the main research content,and a position sensorless hybrid control method is proposed to achieve stable operation in the full speed range of PMSM.The hybrid control method proposed in this paper adopts the double closed-loop current-frequency(I-f)control method in the zero-low speed range,and adopts the improved sliding mode observer control method in the medium-high speed range.The switching between the two methods uses hysteresis control.The innovation of the double closed-loop I-f control method is mainly to apply the improved high-frequency pulse-voltage inj ection method to the traditional open-loop I-f.On the one hand,the closed loop control of the given current amplitude and electrical angular velocity in the I-f control method is realized to improve the disadvantages of the motor being easy to lose steps and low current utilization in the conventional method.On the other hand,the rotor position estimator in the basic high-frequency pulse voltage injection method is removed to avoid the phase lag or parameter dependence.The main work of the improved sliding mode observer control method is to take a series of measures to slow the chattering of the traditional sliding mode observer and improve the rotor position estimation accuracy.By adopting the hysteresis control method,the two methods are switched,and the purpose of low torque ripple,low current fluctuation,simple switching and fast speed in the switching process is achieved.A detailed analysis of principle,complete derivation of theoretical,and specific implementation are given in this paper.The feasibility of the method is verified by MATLAB/Simulink building the corresponding simulation model.The PMSM sensorless control experiment platform is used to test the performance,including zero-low speed,medium-high speed and full speed range,such as light and heavy load starting,speed change and load torque change.Both simulation verification and experimental analysis show that the double closed-loop I-f control method can make the PMSM operate at the state of torque angle of 90°,and the machine has high current utilization and strong anti-load interference capability in the zero-low speed range.The rotor position of the motor is accurately observed and the static and dynamic performance is excellent by the improved sliding mode observer control method in the medium and high speed range.In addition,the switching state is smooth and stable.