Research On Starting Performance Of PMSM Based On Rotating High Frequency Signal Injection Method

Permanent magnet synchronous motor(PMSM)has been widely used in the field of servo transmission for the high efficiency and high power density.At present,the starting performance of permanent magnet synchronous motor with position sensorless control has caused extensive research.In order to realize the stable start of an interior PMSM with load,the effects of signal discretization,digital filter and cross-coupling effect are analyzed,based on the position detection principle of the traditional rotating high frequency signal injection method.And the corresponding compensation strategy is proposed to improve the running performance of the motor with sensorless control.Firstly,the mathematical model of PMSM excited by the rotating high frequency voltage signal is deduced.The digital filters are designed to obtain the negative-sequence current response.The position observer based on the heterodyne method can output rotor position and speed information in real time.The vector control simulation model of high frequency injection method is built by Matlab/Simulink,and the correctness of the position estimation algorithm was verified.The square wave voltage injection method is used to judge the magnetic pole,and the finite element simulation is used to select the amplitude and duration of square wave voltage,which effectively shortens the time consumption.In order to improve the estimation accuracy of the signal injection method,the influence of the signal discretization and digital filters on the phase of the current is analyzed.The relationship between the estimation error and the motor speed is fitted according to the phase frequency characteristic curve of the filter.Observing the cross-coupling effect of the motor with load operation,the effect of the inductance on the position estimation accuracy is analyzed.In the experiment,the estimation accuracy is improved by using the look-up table method.Finally,a hardware control platform for the sensorless control system of PMSM based on DSP is built.Experiments show that the signal injection method can accurately detect the initial position,and the magnetic pole judgment process is stable and takes less time.After the estimation compensation,the signal injection method can obtain a good accuracy,improve the robustness and dynamic response performance of the motor starting process.