Research On The Influence Of Parameter Changes On Sensorless Control For Permanent Magnet Synchronous Motor And The Improved Algorithm

Permanent magnet synchronous motors are widely used in industry due to their superior performance.In order to achieve high performance vector control of permanent magnet synchronous machine(PMSM),feedback of the position and speed of the motor is essential.Installing traditional mechanical sensors can increase the size and cost of the system and reduce the reliability of the system.Sensorless control algorithm extracts the position and speed information of the motor by detecting the voltage and current signals of the motor and sensorless control is one of major development trends of the permanent magnet synchronous motor control.This paper firstly introduces the current research status of sensorless control algorithms for permanent magnet synchronous motors under medium and high speed operating conditions.By adding a low-pass filter and using a saturation function instead of the switching function,the chattering of traditional sliding mode observers is improved.Two sets of back-EMF feedback are used to reduce the sliding mode gain,improve chattering,and accelerate the convergence of the system.In this paper,an additional phase-locked loop is used to obtain the speed and position signals,which are input to the model reference adaptive system as feedforward.It not only accelerates the dynamic response of the system,but also avoids the disturbance caused by the speed feedback.This paper tests the performance of the two algorithms with inaccurate motor parameters and analyzes the sensitivity of the two algorithms to motor parameters.It proves that the sliding mode observer has better performance with inaccurate motor parameters.An improved algorithm with higher fault tolerance is proposed for the actual operating conditions of permanent magnet motors with asymmetric inductance.This paper presents an improved phase-locked loop control algorithm based on the sliding mode observer to improve the stability and estimation accuracy of the sensorless control in the case of inductance asymmetry.The additional resonant controller is used to compensate for the second harmonic error to increase system stability.At the same time,the second harmonic error is used to identify asymmetric self-inductance and correct the inductance parameter in the sliding mode observer to improve the position estimation accuracy.The experimental results obtained from a 400 W SPMSM verify the effectiveness of the proposed method.