| Summary: | 碩士 === 國立中央大學 === 電機工程學系 === 104 === The purpose of this research is to improve the drawbacks of classical direct torque control (Classical-DTC) in the switching table scheme. The approach is based on torque angle control, which is based on the relationship between the stator flux and rotor flux space vectors of the intuition control system. Classical-DTC control uses six valid vectors and two useless vectors on a switching table. However, a feature of this table is that it is either fully open or fully closed in one sampling frequency and achieves fast torque response, which can cause high torque ripple and noise. It is important that the switching frequency be related to system responses. In order to reduce stator flux ripple and torque ripple, the space-vector pulse width modulation (SVPWM) generates different switching states for each sampling time and adapts to overcome the aforementioned problems, especially flux ripple and torque ripple. In the proposed techniques, stator flux amplitude and angle are decoupled from the estimated flux vector. By controlling the reference flux amplitude and angle, torque angle control can be realized. The reference flux is kept constant in this paper. A fuzzy controller is used to compensate for reference flux in order to lessen errors from the transient state response. Speed error is the input of fuzzy controller and the defuzzified value is used to compensate for the reference flux. To demonstrate this method, it was installed on a permanent magnet synchronous motor (PMSM) controller. The simulation result is verified by a PSIM simulator. Finally, the control system is implemented by a digital signal processor TMS320F28335 to achieve a high speed and accurate control system.
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