Realization Of Direct Torque Control Technique For A Three-phase Fault-tolerant Permanent Magnet Motor

More and more safety and reliability are needed in modern electric propulsion system and this high reliable electric propulsion system should have the capability of fault-tolerance. That is the performance of whole system will not be affected when the part of the system or its subsystem broken down. In the electric propulsion system, improving motor’s fault tolerant reliability is an important way to improve the system’s performance. The state winding in each phase of a brushless fault tolerant permanent magnet (FTPM) motor is not overlapped; therefore the windings are physical isolation. Thus the motor has both of the advantage of high efficiency, low noise, and the ability of fault-tolerance.The essence of controlling motor is controlling the magnetic torque. In order to obtain high static, dynamic torque characteristics, a DTC method for a three-phase FTPM motor is proposed in this thesis. Firstly, the structure of a three-phase FTPM motor is analyzed and the mathematical models for this motor drive are established. Secondly, based on the coordinate transformation theory, the mathematical models are decoupled. Then, connecting with the transform circuit of the FTPM motor drive, the specific control strategy is determined. In order to validate the correctness of the control strategy, the model of a three-phase FTPM motor and the simulation models to realize the DTC for this motor drive through calculating sector position and controlling flux linkage and torque in MATLAB/Simulink environment are eastablised. The simulation results have shown that the satisfactory waveforms of flux linkage, speed and torque can be achieved.To further verify the feasibility of the control strategy, the experimental setup based on TMS320F2812 is built. The hardware of this setup includes power transform circuit module, drive and isolation module and detection module. The software is written and debugged in CCS3.3 environment. The experimental results have shown that the experimental setup is able to realize the direct torque control of FTPM motor.