Research On Vector Control Technology Of Sensorless Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM)have the advantages of energy saving,high efficiency,small size and easy speed adjustment.These characteristics make it have unlimited development space in the fields of industry,household appliances and new energy vehicles.In the PMSM control system,the rotor position is usually obtained by sensors.But sensors have requirements for the workplace and the price of different sensors will affect the cost of the system.Therefore,using algorithm to replace the position sensor is a major topic of research discussion.This paper takes the surface-mounted permanent magnet synchronous motor as the research object.Aiming at the problem system chattering caused by the sliding mode observer and the problem of reducing the system bandwidth by high frequency injection method,the following studies have been done:First,according to coordinate transformation,the mathematical model of the motor and space vector pulse width modulation technology,a current and speed double closed-loop vector control system is constructed,which which provides a mathematical model and framework for the sensor-less permanent magnet synchronous motor vector control.Secondly,this paper designs an adaptive sliding mode observer to reduce the chattering problem of the traditional sliding mode observer observing the back EMF.Compared with the traditional sliding mode observer,the adaptive sliding mode observer designed in this paper replaces the sign function with a new control function,replaces the filter link with the back-EMF adaptive link,and uses the phase-locked loop module to improve the accuracy of the position estimation module.The simulation results show that the steady state error between the estimated value and the actual value of the position within 0.15rad,the adaptive sliding mode observer can reduce chattering in the high-speed stage,more effective to estimate the position of the rotor.Then,the pulsating high-frequency square wave voltage injection method is used to observe the position and speed of the rotor in the low-speed stages.The pulsating high frequency square wave voltage injection method can reduce the use of filters and improve the stability of the system.In the traditional pulse voltage injection system,a large number of filters are needed to extract the corresponding high-frequency current signal and low-frequency current signal,which reduces the bandwidth of the system and also increases the complexity of the software algorithm.The simulation results show that the pulsating high-frequency square wave voltage injection method can effectively estimate the position of the rotor and track the speed of the rotor without using a filter in the low-speed range.In order to make the pulse vibration high frequency square wave voltage injection method and the adaptive sliding mode observer realize the smooth switching of the speed,a weighted switching method is used to establish a composite observer.The simulation results show that the compound observer can realize the full speed range position estimation of PMSM.Finally,the corresponding hardware circuit of the sensorless permanent magnet synchronous motor vector control system is designed,and the functions of the main modules are analyzed.On the experimental platform,the upper computer performs a position estimation experiment on a 200W PMSM at 900rpm and 150rpm.Experiments show that the difference between the estimated value and the actual position is within 0.1rad and 0.15rad,which verifies that the algorithm in this paper can realize the position estimation and speed estimation in the high-speed and low-speed domains.