Research On Fault Tolerant Control Strategy Of Single-phase Bridge Arm Fault In Dual Three-phase Permanent Magnen Synchronous Motor Drive System

Compared with the traditional three-phase motor,multiphase motor has the advantages of high output power,strong fault tolerance and low torque ripple,especially in the field of electric traction,electric vehicles,ships and other fields,which has broad application prospects.Dual three-phase permanent magnet synchronous motor(PMSM)is taken as the research object in this thesis.Mathematical model,harmonic current suppression and fault-tolerant control strategy after single-phase bridge arm fault in the drive system are deeply studied.Firstly,the basic mathematical model of two-phase and three-phase PMSM is introduced,and the control principles of two-dimensional,four-dimensional current control and direct torque control strategy based on the vector space decoupling(VSD)theory are respectively described in this thesis.Secondly,a direct torque fault-tolerant control strategy based on virtual voltage vector is studied for single-phase bridge arm fault of dual three-phase PMSM drive system.The dimension of the system under fault is reduced,and then the virtual voltage vector after phase loss is modified and optimized to obtain the proportion of the virtual voltage vector and its basic vector corresponding to the maximum amplitude,the direct torque control strategy is used to control the system under phase missing.Furthermore,aiming at the problem that the copper consumption of the stator increases when the motor operates in fault-tolerant mode,the fault-tolerant control system of six groups of dual three-phase PMSM driven by five leg inverter is studied,and the AF common mode,CF common mode and BF common mode of the five leg system are deeply analyzed.The double zero sequence injection PWM strategy and the direct torque fault-tolerant control strategy based on virtual voltage vector are discussed.According to the theoretical analysis and the proposed control strategy,the simulation circuit model based on Matlab/Simulink software is built.The experimental prototype platform of dual three-phase PMSM drive system is built for experimental verification.Simulation and experimental results verify the rationality and feasibility of the fault-tolerant control strategy.