Abstract
This thesis is mainly concerned with the development of a switched-reluctance motor (SRM) drive powered from utility grid via a single-phase bridgeless switch-mode rectifier (SMR) frond-end. And some performance enhancement control approaches are proposed and evaluated experimentally. First, a three-phase SRM drive with suited current and speed controls is designed and implemented. For the developed current control scheme, the current feedback controller (CFBC) is augmented with an observed back electromotive force (EMF) current feedforward controller (CFFC). Moreover, a dynamic commutation shift controller (DCSC) using sensed winding current is proposed to further counteract the back-EMF effects automatically. Having well-designed current control loop, good speed control performance is achieved by the designed control scheme. Under higher speeds and/or heavier loads, the effectiveness of commutation advanced shift is limited, and DC-link voltage boosting becomes the sole means. To achieve this goal, a single-phase bridgeless boost SMR is then developed to establish the boostable and well-regulated DC-link voltage for the followed SRM drive. Compared to the traditional boost SMR, the bridgeless schematic leads to the increased efficiency. As to the proposed control scheme, the proportional-plus-integral (PI) feedback controllers are augmented with simple robust cancellation controllers to enhance the current and voltage control dynamic responses. Finally, the effects of commutation on the DC-link current ripple and the stator vibration characteristics are explored experimentally. Then accordingly, a DCSC based on sensed DC-link current is devised for achieving the DC-link current ripple minimization automatically. The effectiveness of the developed control approach is verified by some measured results.