MTPA Based Sensorless Control of a Half-Wave Rectified Rotor Excited Synchronous Motor

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Addis Ababa University


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



Electric Vehicle (EV), Maximum Torque Per Ampere (MTPA) Control, Sensorless