Rotor Position and Velocity Estimation Method for Permanent Magnet Synchronous Motor Based on Sliding Mode Observer

Abstract

The invention discloses a method for estimating the rotor position and speed of a permanent magnet synchronous motor based on a sliding mode observer. The sliding mode observer is a sliding mode observer based on a boundary layer self-adjusting arcsine saturation function, and the sliding mode observer includes a current state Observer, current comparator, boundary layer self-adjusting arcsine saturation function module, extended Kalman filter and software phase-locked loop. The present invention replaces the sign function in the existing sliding mode observer with a self-adjusting arcsine function based on the boundary layer, and simultaneously uses the extended Kalman filter to extract the extended back electromotive force, and removes the low-pass filter in the existing sliding mode observer, And the extracted extended back electromotive force is fed back to the current state observer for amplitude compensation. Compared with the existing sliding mode controller, the sliding mode observer based on the boundary layer self-adjusting arcsine function provided by the present invention can effectively suppress the torque ripple, improve the steady-state performance of the system, and improve the tracking accuracy of the rotor position and rotational speed.

Description

technical field [0001] The invention relates to the field of electromechanical control, in particular to a method for estimating the rotor position and speed of a permanent magnet synchronous motor based on a sliding mode observer. Background technique [0002] The position sensorless control technology samples the relevant electrical signals in the motor to estimate the rotor position and speed information, and removes the mechanical position sensor, thereby reducing the system volume and weight, reducing the cost and hardware complexity, and improving the system performance. [0003] The position sensorless control methods of permanent magnet synchronous motor mainly include high frequency injection method and observer method, and observer methods include extended Kalman filter, model reference adaptive and sliding mode observer, etc. Among them, the sliding mode observer is a nonlinear control method, which has a simple structure, low modeling accuracy requirements, and s...

AI Technical Summary

Problems solved by technology

Among them, the sliding mode observer is a nonlinear control method, which has a simple structure, low modeling accuracy requirements, and strong robustness, but it also has the problems of large system chattering, delayed position angle and phase, and poor steady-state performance.

[0004] The traditional sliding mode observer uses the sign function as the control function of the sliding mode surface, which leads to serious chattering of the system. There are a large number of harmonics in the observed back EMF, which affects the speed estimation accuracy, and the torque ripple is large. Using the saturation function instead of the sign function can effectively reduce the Small system chattering, but the boundary layer thickness of the saturation function is often fixed at a constant value, which can cause poor steady-state performance at certain speeds or under certain load conditions

Using a low-pass filter can effectively filter out high-frequency harmonics, but it will cause a decrease in the amplitude of the back electromotive force and a delay in the position angle phase, requiring additional position compensation

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