Research On Open Phase Fault Diagnosis And Fault Tolerant Control Strategy Of Seven-phase Induction Motor Based On Vector Control

In recent years,due to the increasing demand of modern industry,in the electrification industries such as new energy vehicles,ship electric propulsion systems,high-speed traction rail transit,etc.,in order to obtain greater power and torque,multi-phase induction motor and its drive system,a power drive system that has the advantages of higher degree of freedom,high reliability,low voltage and high power compared with the three-phase motor and its drive system,have begun to be widely concerned and developed.This article will take the seven-phase induction motor as the research object to study its open-phase fault diagnosis and fault-tolerant control strategy.The main contents of the article are as follows:First of all,this article introduces the research advantages of multi-phase motor drive systems in modern industrial applications,and gives a detailed introduction to the research part of multiphase induction motor open-phase fault detection and fault-tolerant control.The necessity and importance of the research of these two modules for the application environment of multiphase motors are be explained.Secondly,the winding function is used as the starting point to analyze the time and space harmonic magnetomotive force distribution of the multi-phase induction motor,and the relationship and essence of the multi-plane operation of the multi-phase induction motor are explained.And by expanding the Clarke coordinate transformation matrix of the three-phase induction motor,the multi-phase Clarke coordinate transformation matrix is derived,and the mathematical model of the multi-phase motor in the synchronous rotating coordinate system is obtained,so as to realize the decoupling control of multiple planes.The principle and structure of the vector decoupling control based on the rotor field orientation of the multi-phase motor are introduced,and the mathematical foundation and control strategy foundation are consolidated for the subsequent research and verification.Thirdly,in order to ensure the reliable operation of the motor while reducing the loss caused by the fault,the seven-phase induction motor is taken as the research object,and its open-phase fault diagnosis strategy is studied.By analyzing the relationship between the plane currents of the seven-phase motor after the phase is broken,in order to realize the rapid detection after the fault,a fault diagnosis method based on the transformation of the proportional relationship between the fundamental wave and the harmonic plane current is proposed,and providing information for the next step into the fault-tolerant control link and system maintenance work.Finally,in order to keep the magnetomotive force unchanged before and after the fault as the control purpose for the problems such as the open phase fault caused by the harsh or special operating environment,consider the recalculation and construction of the remaining phase current after the fault.A fault-tolerant control strategy based on vector decoupling transformation of positive and negative sequence currents is proposed.The multi-plane characteristic of the motor realizes the control of the reference value of the harmonic plane current,realizes the disturbance-free operation of the motor after the fault,and improves the operation stability and safety of the motor control system.And the reliability and effectiveness of this fault-tolerant strategy are verified through experiments.