Research On Sensorless Control Method Of Permanent Magnet Synchronous Motor At Full Speed Range

In recent years,with the comprehensive promotion of the"Made in China 2025"national strategy,China's new energy vehicles have been vigorously developed.Due to the advantages of simple structure,small size,light weight,and good dynamic performance,permanent magnet synchronous motor(PMSM)is widely used as driving motor in the field of new energy vehicles.When controlling a PMSM by vector control,it is necessary to accurately detect the real-time position and operating speed of the rotor.Usually,a mechanical sensor is installed on the shaft of the rotor.The disadvantage is that it would not only increase the cost of the entire system,but also reduce the working reliability of the system,which is affected by the complex driving environment of pure electric vehicles.Therefore,it is of great practical significance to study the sensorless control technology of PMSM.The concrete research contents of this paper are as follows:(1)As the basis of PMSM sensorless control technology,it is necessary to study the vector control of PMSM firstly.Therefore,this paper introduces how to deduce the mathematical model of PMSM in different motion coordinate systems and the theory of coordinate transformation between coordinate systems,and then introduces and analyzes the theoretical basis and design idea of vector control in PMSM in detail.Finally,the system modeling and simulation analysis of i_d=0 vector control system are carried out.(2)Based on the PMSM i_d=0 vector control system,a sensorless control system based on model reference adaptive is designed,which is suitable for medium and high speed range.And the basic principle is elaborated in detail.According to the theory of Popov hyperstability,the reference model and the adjustable model are constructed,and the appropriate adaptive law is derived.Finally,the stability of the system is proved.The model reference adaptive sensorless control method is modeled and simulated with Simulink.(3)In order to solve the problem that the accuracy of the sensorless control method based on fundamental wave model becomes worse or even invalid at low or zero speed,a sensorless control system based on salient pole model is designed,which is suitable for low speed range.Firstly,the mathematical model of PMSM in high frequency environment is deduced,and the basic principles of two high frequency voltage injection methods are elaborated in detail.Then,the principle analysis and detailed formula derivation of how to extract the rotor position estimation are given,and the two kinds of high frequency signal injection method of sensorless control system are modeled and simulated with Simulink.Finally,in order to realize sensorless control in full speed range,a composite control method based on weighted switching is adopted,and the full speed range of the sensorless composite control system is modeled and simulated,which verifies the feasibility and effectiveness of the sensorless control technology in the full speed range.It provides a theoretical basis for the application of the sensorless control technology of permanent magnet synchronous motor in the field of pure electric vehicle,and has a certain practical value.