Noninductive Control of Permanent Magnet Synchronous Motor Based on Improved Synovial Observer

In the non-inductive control of permanent magnet synchronous motor, the rotor position information of the motor is usually estimated by the synovial film observer. Synovial observer has the advantages of simple control structure and short response time. The switch function of the control process of the synovial observer is usually the sign function. The back electromotive force signal is extracted by the filter, and then the rotor position information is estimated by the inverse tangent method. However, the traditional switching process of sign function contains a large number of high order harmonics, which will cause the problems of phase difference and amplitude attenuation after the signal is filtered by the filter, and the estimation error of arctangent method is large. Based on the above problems, the traditional switching function is improved in this paper. Continuous sigmoid function is used as the switching function, which can effectively solve the problem of excessive vibration during the operation of the motor. In addition, phase-locked loop technology is introduced to replace the traditional inverse tangential method for rotor position estimation, which further improves the estimation accuracy of the system.