Research On Full Speed Control Strategy Of Permanent Magnet Synchronous Motor Without Position Sensor

Permanent Magnet Synchronous Motor(PMSM)has been widely used in many working conditions because of its advantages of high power density,high efficiency and small size.Due to the strong coupling and nonlinear characteristics of PMSM,the performance of traditional PMSM double closed loop vector control system is easily affected by the change of external parameters,and this method needs to install accurate position sensors on PMSM.For some special working conditions,the installation of position sensors will affect the robustness of the control system,and the use of sensorless position sensor technology can improve the above problems to a certain extent.Therefore,this paper takes the surface mount PMSM as the research object,and researches the control strategy of the full speed domain without position sensor of permanent magnet synchronous motor.Firstly,to solve the problem of poor robustness of speed loop PI controller in traditional PMSM double closed loop vector control,a new exponential reaching law was proposed by introducing fal(s,α,δ)function,and its feasibility was verified and analyzed.Based on the reaching law,a speed loop sliding mode controller and sliding mode observer were designed.It is compared with traditional exponential reaching law and fast exponential reaching law.The simulation results show that the controller and observer designed based on the new approach law have a good estimation effect in the medium and high speed domain.Secondly,in order to improve the estimation accuracy of speed and rotor position in the low speed domain,the high frequency signal injection method in the low speed domain is introduced,and the pulse vibration high frequency signal injection method is selected as the low speed domain control method according to the characteristics of surface mount PMSM.Aiming at the phase shift problem of the low-pass filter used in this method,the Second Order Generalized Integrator(SOGI)is introduced to eliminate the phase shift problem of the low-pass filter to a certain extent,and the SOGI is improved on this basis.By introducing high-order Butterworth low-pass filter,the attenuation ability of SOGI to high-frequency harmonics is further improved,and the comparison between SOGI and low-pass filter is made.The simulation results show that the improved SOGI based pulse vibration high frequency signal injection method can estimate the speed and rotor position in low speed domain with high accuracy.Finally,in order to improve the compound control effect of low speed domain and medium speed domain control methods,a weighted switching algorithm is introduced as a transition between low speed domain and medium speed domain,and the upper and lower limits of the weighted switching algorithm are determined by linear input,and the composite control simulation of the full speed domain is carried out.The simulation results show that the estimation effect of the composite control strategy has a good performance in the steady state process and the dynamic process.