The Research On Improved Fault-tolerant Control Strategy For Multi-phase Induction Motor Running Without Phase

Multi-phase motors are continuously gaining more and more attention and research of motors due to their high reliability,flexibility,and ability to achieve high power output at low voltage and suppress torque ripple.Increase and gradually apply to some special occasions.This disertation mainly analyzes and researches the mathematical model of multi-phase induction motor and allow-error manipulate strategy in the absence of phase.This disertation first introduces and analyzes the body structure and magnetomotive force distribution of the multi-phiaes induction motor,deduces and establishes the mathematical model of the motor under the standard basis,and then uses the space vector decoupling transformation theory to decompose the complex physical quantities in the m-dimensional space To several harmonic subspaces perpendicular to each other,the mathematical model of the multi-phase motor under the harmonic basis is established,which paves the way for the subsequent specific analysis.Taking a six-phase induction motor as an example,a mathematical model of a six-phase motor is established and a simulation model is built in Matlab / Simulink software for simulation waveform analysis.Then the performance characteristics of the six-phase induction motor after phase loss are analyzed and studied.The six-phase motors lack one-phase and two-phase faults are classified and discussed respectively,the space vector decoupling transformation matrix of the motor lacking one phase and two phases missing in different situations is derived,and the six-phase induction motor is carried out by using Matlab/Simulink The simulation analysis of the lack of phase operation shows that the amplitude of the residual phase current will increase after the phase loss of the motor,and at the same time,the speed and electromagnetic torque of the motor will pulsate.In order to effectively use the remaining phases to maintain the continuous operation of the motor after the phase loss of the motor and realize the fault-tolerant control of the multi-phase motor,this paper studies and analyzes the fault-tolerant control of the multi-phase induction motor from three aspects.Among them,the control strategy of optimal current injection based on the constant stator magnetomotive force can calculate the phase and amplitude of the effective phase current after the missing phase of the motor according to different optimization goals according to the principle that the total stator magnetomotive force of the motor is unchanged.Based on the d-axis rotor magnetic field orientation control method,according to the mathematical model of the harmonic basis after the phase loss,through the modified rotation transformation,the excitation component and torque component of the current are truly decoupled,thereby realizing the multi-phase electrical machineField-oriented control after phase loss.In the analysis of the fault-tolerant control method based on direct torque control,the space voltage vector of the motor after the single-phase phase loss is analyzed,and the stator flux linkage and Dynamic control of torque.Finally,on the premise of analyzing the advantages and disadvantages of the two optimization goals of maximum torque and minimum copper consumption in the control strategy based on the optimal current injection with constant stator magnetomotive force,a fault tolerance based on variable current injection is proposed Control strategy,by setting the plane current reference value,setting the y-axis current reference value to a variable current,switching between ML mode and MT mode according to the actual situation of the motor electromagnetic torque,so that the six-phase motor will lose copper The smallest,which greatly improves the efficiency of the motor.