Wide-speed sliding-mode observer of sensorless brushless direct-current motor

Abstract

The invention discloses a wide-speed sliding-mode observer of sensorless brushless direct-current motor. Speed application range of the sliding mode observer can be enlarged by the aid of the wide-speed sliding-mode observer, estimation in wide-speed range is realized, and speed control on a wider range is realized. Reference input speed of the brushless direct-current motor is divided into three speed intervals of low speed, medium speed and high speed, and boundary layer thickness is adjusted according to the different reference input speed of the direct-current motor; the boundary layer thickness is increased in low speed, and chattering is effectively suppressed; the boundary layer thickness is reduced in high speed, and response speed of the observer is increased, error of estimation is reduced, observation range and estimation precision of the sliding-mode observer are accurately improved as a whole, and better estimation effect and wider range of speed control are acquired; meanwhile, sinusoidal saturation function is taken as sliding-mode surface function, effective chattering suppression can be achieved without using a low-pass filter, and the sliding-mode observer is fast in convergence and high in estimation precision.

Description

technical field [0001] The invention relates to the technical field of electromechanical control, and relates to a position sensorless control system of a brushless DC motor, in particular to a wide-speed sliding mode observer of a brushless DC motor without a position sensor. Background technique [0002] The brushless DC motor (Brushless DC Motor, BLDCM) can realize the electrical connection between the stator and the rotor of the motor without brushes. It combines the characteristics of DC motors and AC motors, and has simple control methods, high torque characteristics, and dynamic response. The advantages of fast speed, good speed regulation performance and simple manufacturing process are especially suitable for occasions with high requirements on space size. [0003] In order to ensure the normal and continuous operation of the brushless DC motor, it is necessary to obtain the position information of the rotor through the position sensor for commutation. However, the...

AI Technical Summary

Problems solved by technology

The extended Kalman filter has complex algorithms and structures, which limits its promotion in practical engineering

In order to obtain good results for system parameter identification, artificial neural network often adopts online identification method, which introduces the disadvantages of time-consuming and low real-time performance.

The model reference adaptive method is too sensitive to parameters. If the reference model is not selected correctly, the system may diverge, so the stability is poor

Different from the above three methods, many scholars have proposed a simple and easy-to-implement sliding mode observer method, which is robust to internal parameters and external disturbances, but the robustness still needs to be strengthened. There is inherent chatter that cannot be eliminated

In addition, most of the currently commonly used sliding mode observers are only suitable for a specific speed range, and there is a disadvantage of large estimation error when the speed is too low or too high

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