| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系電力電子產業碩士專班 === 106 === The sensorless control strategies for PMSM drives mainly include high frequency (HF) injection and position observer based on motor model. The information of rotor position depends on the inductance difference between q axis and d axis for low speed. Due to the saliency ratio of SPM is relatively small, it’s hard to estimate the rotor position by the characteristics of inductance. A sensorless speed control is proposed in this thesis. The phenomenon of current rise caused by the saturation of inductance, when the rotor magnet is approaching to the stator coil, is utilized as the detection basis at standstill. To identify the state of the six current vectors and their magnitudes under 180 degree conduction, thereby the rotor position is estimated at standstill. Then, the 120 degree commutation is applied for low speed operation. The magnetic saturation occurs when the rotor magnet is close to the excitation stator windings, therefore the open phase winding will yields an electromotive force due to the change of magnetic flux. The current commutation of six-switches is according to detect the open phase voltage within six switch states.
Finally, a DSP-based(TMS320F28035) motor drive is built to verify the effectiveness of
the proposed strategy with a 350W/6000rpm SPM.
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