| Summary: | 博士 === 國立臺灣科技大學 === 電機工程系 === 104 === This dissertation proposes a dual-permanent-magnect-synchronous- motor drive system to increase its efficiency and to extend its constant-torque operation speed range. The proposed drive system can be separately operated at a low-speed operation mode and a high-speed operation mode. In the low-speed operation mode, the output torque is shared by the dual motors. A maximum efficiency control is proposed by suitably adjusting the distribution ratio between the two motors, so a maximum efficiency of the whole drive system can be achieved. In the high-speed operation mode, one motor is maintained at standstill and its stator windings are used as inductances of a boost converter to increase the dc-bus voltage. As a result, the second motor can extend its constant-torque high speed operation range. In addition, the energy recovery is investigated to charge the batteries and to reduce charging current ripple during a braking action.
A predictive speed-loop controller and a predictive current-loop controller are designed to improve the fast transient responses, load regulation responses, and tracking responses. Finally, a fault tolerant control method is investigated. When a power device of the inverter is short circuited or open circuited, a simple method is proposed to make the output torque keep near a constant; therefore, the reliability of the drive system can be improved.
A digital signal processor, TMS-320-F-2808, is used as a control conter to realize the proposed control methods. Experimental results can validate the correctness and feasibility of the proposed method. The proposed method can be applied in electric vehicle because of its simplicity.
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