Research On Position Sensorless Control For SPMSM Based On Pulse High-Frequency Voltage Injection Method

The vector control of permanent magnet synchronous motors requires real-time rotor position.Traditional mechanical position sensors have high costs,and they are prone to damage when working in complex environments,reducing the service life of the motor system and increasing maintenance costs,which to some extent limits their application.Therefore,sensorless control is a hot topic in the application research of permanent magnet synchronous motors.This article studies the non-inductive control of surface mounted permanent magnet synchronous motors based on the pulse high-frequency voltage injection method.Firstly,the structure and classification of permanent magnet synchronous motors were introduced,decoupling thinking was introduced,and the mathematical model and coordinate transformation principle of permanent magnet synchronous motors were analyzed.Combined with vector control block diagrams,modules such as SVPWM and PI were explained.The vector control method with i_d=0 was used to achieve dual closed-loop control of the motor control system.Secondly,this article analyzes the principle of pulse oscillation high-frequency voltage injection method.A voltage pulse injection based motor rotor polarity judgment method is proposed to address the issue of traditional high-frequency voltage injection methods that can accurately estimate the initial position of the rotor,but cannot identify rotor polarity.However,existing rotor polarity judgment methods have problems such as long initial position detection execution time,complex sampling and implementation process,dependence on motor parameters,and polarity misjudgment.This method applies positive and negative voltage pulses on the d-axis,and correctly judges the rotor polarity based on the peak response current of the corresponding pulse.Applying the initial position detection of the rotor to the pulse high-frequency voltage injection method,by combining the initial estimated value of the rotor position with the polarity judgment result,accurate initial position of the rotor can be obtained,solving the problem of rotor polarity judgment.The experimental results show that this method can accurately determine the polarity of the rotor,with a fast convergence speed.The average position error after convergence is 6.7°,and the detection time is 0.23 seconds.This enables the pulse high-frequency injection method to accurately and quickly estimate the initial position of the rotor.In response to the problem of instantaneous current impact on the control circuit and motor at the initial moment caused by traditional signal injection methods that inject voltage signals with large amplitudes before the rotational speed is unstable,this paper proposes slow voltage injection.This method changes the sine wave signal with a fixed amplitude to a sine wave signal with an amplitude gradually increasing from 0 to a given amplitude.In order to further optimize the performance of the pulse oscillation high-frequency voltage injection method,this article analyzes the filter parameter setting method and the injection signal frequency and amplitude setting method of the pulse oscillation high-frequency voltage injection method.To address the issue of the inability of the pulse high-frequency voltage injection method to observe position and velocity information in the medium to high speed stage,a weighted hysteresis method is adopted to combine the pulse high-frequency voltage injection method with a sliding mode observer to achieve composite control.The experimental results show that a slow voltage injection time step of 0.15s and an injection voltage amplitude of 6V can effectively reduce the impact.The injection voltage amplitude is 6V,the frequency is500Hz,and the estimated position accuracy is high.The average position error during low-speed operation is 5.7°.Weighted hysteresis switching can achieve smooth switching between the two algorithms,with minimal sudden changes in speed.Finally,this article designed and implemented a motor controller with STMS32F446RCT6 as the main control chip,and programmed algorithms such as vector control,high-frequency injection method,and rotor polarity judgment method.The experimental results verify the feasibility of the proposed method in this paper.