Direct Torque Control Of Fault Tolerantpermanent Magnet Motor Based On Three-phase Four-leg Inverter

Among the key drive control systems of the more electric aircraft, electromechanical actuators have been seen everywhere.Therefore, design of a motor control system with high reliability is realistically urgent and valuable. Fault-tolerant technology can ensure the system continue to run safely after multiphase break down. Compared to redundant technology, fault tolerant technology has the advantage of high power density and is the advanced stage of reliability technology.This paper concludes the advantages and disadvantages of direct torque control(DTC)based on independent H bridge topology, then proposes the direct toruque control of fault tolerant permanent magnet motor(FTPMM) based on three phase four bridge. It gives the inverter and motor winding fault identification method, and analyzes the control strategy of the normal state and fault state independently. In the normal state, the control system uses direct torque control based on voltage space vector modulation method driven by three-phase full bridge and selects the current model of the stator flux estimation. Also, the stator flux linkage amplitude given is optimized. In the failure state, when a single power tube or a phase winding failure occurs, the fourth bridge arm is controlled according to the specific situation to guarantee that the space voltage vector of fault is unchanged, so the direct torque fault tolerance control is realized. Simulation model is built by Matlab/Simulink to verify the theory above.Based on the hardware platform, software design is given for the direct torque control system of FTPMM,including the DSP control part and the CPLD faulttreatment part. On this basis, experimental results verify effectiveness of the direct fault-tolerant control algorithms in normal and fault state.