Abstract
The thesis is mainly concerned with the development of a DSP-based synchronous reluctance motor (SynRM) drive and the exploration of its position sensorless control. First, some key affairs of a SynRM are explored, including motor structures, governing equations, parameter estimation, rotor position sensing and commutation instant setting, etc. Then, a standard SynRM drive is established and evaluated. Good driving performance is preserved thanks to the proposed adaptive commutation shift approach. Considering the effects of iron loss and magnetic saturation, the commutation angle is automatically set to pursue the maximum efficiency, and thus the maximum torque per ampere (MTPA). In addition, a field-weakening commutation method is also developed to enhance the motor operating characteristics in higher speed region. Second, the grid-connected SynRM drive is developed. A three-phase six-switch four-quadrant SMR is developed and used to power the motor drive from the mains. The boosted and well-regulated DC-link voltage is established to improve the motor driving performance with good line drawn power quality. Moreover, the regenerative braking with energy being recovered to the utility grid is successfully achieved. Third, the position sensorless controlled SynRM drives based on different high-frequency injected (HFI) signals are developed and comparatively assessed. The HFI sensorless drive using sinusoidal injected signal is first established. After exploring the slotted harmonic effects, the HFI scheme with changed frequencies is proposed to yield the improved driving performance in wide speed range. Next, the position sensorless control scheme of SynRM using high-frequency square wave injection is developed. The simplified estimation procedure and faster speed response compared to the first one can be obtained.