Research On Fault-Tolerant Control Of Permanent Magnet Brushless Motors And Design Of Drive System

Permanent magnet brushless motors are widely used in AC servo drive systems due to their high power density,excellent performance and high reliability.In the ideal permanent magnet brushless DC motor drive system,it is assumed that the Hall position sensor is installed at the absolute position of the phase winding axis of the motor,and the rotor position signal with the 60° electrical angle position resolution makes the motor commutate precisely.However,in the actual drive system,,the Hall sensor may be faulty when the motor is in a strong magnetic field environment or the voltage shock in the drive system is large,which will affect the normal running state and performance of the motor.Therefore,it is of great practical engineering significance to study the Hall position sensor fault diagnosis and compensation of permanent magnet brushless DC motor.In this thesis,the advantages and disadvantages of existing Hall fault diagnosis techniques were summarized by reviewing the literatures for single Hall and double Hall fault types that may occur with Hall sensors,and a fault detection method based on Hall vector phase is proposed.This method diagnoses 18 fault types by detecting changes in the vector phase obtained by Hall state vector conversion at the edge of the Hall transition.At the same time,the influence of various fault types on rotor position estimation accuracy is analyzed.And the existing fault-tolerant control algorithm and rotor position estimation algorithm are summarized.Two fault-tolerant control strategies are proposed: improved hybrid observer compensation method and improved interpolation fault-tolerant control algorithm.Considering the problem of the Hall sensor installation error and the speed response delay of the interpolation algorithm,the estimation accuracy of the average speed is improved from the viewpoint of the average speed calculation,so that the estimation accuracy of the rotor position is improved.Finally,Altium Designer software is used to design the motor driver,including the power supply circuit,the inverter circuit,the drive circuit(including two schemes: directly composed of the driver chip and built with discrete components),current and voltage sampling circuit and design of peripheral circuit of main control chip.Finally,the software programming design of the proposed Hall fault diagnosis and fault-tolerant control strategy is carried out based on the TMS320F2812 DSP at the built motor control test platform.The effectiveness and reliability of the proposed algorithm was verified by simulating the failure of the Hall sensor in steady-state operation and dynamic operation(including acceleration transient and variable load).The experimental results which include the output of the Hall signal,the motor winding line voltage,the phase current output,the rotational speed output,and the rotor position waveform,are analyzed and compared with the theoretical part of the proposed strategy.It can be seen that the Hall fault can be quickly diagnosed.And the proposed fault-tolerant control algorithm has good steady-state performance and dynamic performance.