Mtpa Based Sensorless Control Of A Half-wave Rectified Rotor Excited Synchronous Motor

In this thesis, Maximum Torque Per Ampere (MTPA) based sensorless Field-Oriented Controlrn(FOC) of the Half-wave Rectified Rotor Excited Synchronous Motor (HRreSM) for Electric Vehiclern(EV) traction drive application is presented. The traction motors in EVs are responsible torndeliver the maximum possible torque for the vehicle’s propulsion and the motor should have a fluxrnweakening capability for the high speed range drive of the vehicle. HRreSM has simple, robustrnand maintenance free mechanical structure with brushless means of field excitation. Variable fieldrnflux and torque control capability of HRreSM can be supported by the proper control strategiesrnto increase the efficiency of the motor drive system. Two consecutive control strategies, MTPArnand Flux Weakening (FW), with in the FOC are implemented to study and verify the performancernof the controlled motor drive system for the proposed EV application. Since the position of thernrotor flux is crucial in a FOC system, a sensorless rotor position information extraction methodrnbased on the bias frequency component of the stator current is implemented. The proposed drivernis demonstrated by simulation on linked MATLAB/ Simulink and Ansys Electronics/ Simplorerrnenvironments.Simulation results show that, the extracted (estimated) rotor position perfectly tracks the actualrn(sensed) position in the whole speed range of the motor. The extracted rotor position of the motorrnis compared with the actual rotor position for validation. And The MTPA control performance hasrnbeen compared to the constant irncontrol strategy, and 52.78% more torque generation is registeredrnby the MTPA control model. The performance study of the FW control strategy is made by makingrna comparison between MTPA based model (for the whole speed range) and MTPA and FWrnbased model (FW applied after the base speed of the motor). And 21.97% speed extension beyondrnthe speed limit of the MTPA based model is obtained by implementing MTPA and FW controlrnstrategies consecutively. Therefore, the developed sensorless drive model, with good torque performancernand speed range extension beyond the base speed of the motor, is verified to be efficientrnfor EV traction drive applications.

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