| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 87 === This thesis presents a high-performance torque control system applied to brushless motors for electric vehicles, with the aim of achieving output characteristics similar to that of Continuously Variable Transmissions. Three compensated methods are used in the proposed torque controller, the first of these methods is the phase advance control, which controls the stator phase currents to in-phase the back EMF. The second method is back EMF compensation, which can avoid the disturbance of the back EMF. The third method uses current loop gain compensation, which varies the control gain based on motor speed and is used because of the nonlinear characteristics of the system. Then, the brushless motors applied to the electric vehicles requiring wide-speed operation. In this thesis, the phase advance control technique is adopted to get more torque output in the low speed range, and a field weaken control which uses more phase shift to weaken the magnetic flux of the motor in order to achieve wide rang of motor speeds. Finally, a fully digital control scheme is proposed to improve overall performance and to verify the experimental results correspond to the theoretical analysis.
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