Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 88 === Direct-driven wheel motor is one of the solutions to increase the efficiency of electric vehicles, especially, at low speed with required large torque. This paper aims to the design of the optimal current waveform for an axial-flux brushless permanent magnet motor, so that its output torque is maximized under prescribed constraints. First, the torque equation is derived by he energy method and modified according to the characteristics of the wheel motor. Second, the parameters that describe the relationship between torque and input current are introduced in the magnetic circuit model. Three different sets of constraints are then prescribed for various driving and winding structures. Finally, the optimal current waveform for independent winding with constrained copper loss is proved to be best in terms of maximum efficiency and output torque.
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