Abstract
This thesis goes into the development of switched-reluctance motor (SRM) drives powered by different kinds of AC/DC front-ends and making their experimental comparative evaluation. To begin with, the key affairs concerning SRM drive and comparative features of some commonly employed AC/DC converters are explored. Then a three-phase diode rectifier powered SRM drive is established. The asymmetric bridge converter is adopted to construct the SRM drive owing to its high PWM switching control flexibility. Through applying the proposed commutation shifting, current and speed control approaches, better driving characteristics, including acceleration/ deceleration, reversing rotation, regenerative brake and high-speed driving are achieved. Under higher speeds, the current tracking performance will be gradually deteriorated due to the limited field-weakening effect via commutation advanced shift. The DC-link boosting must be applied instead. To accomplish this goal, some power factor corrected (PFC) AC/DC converters, or called switched-mode rectifiers (SMRs), are established and evaluated. A standard full-bridge boost SMR is first built as the active front-end of the SRM drive. With the help of this four-quadrant SMR, the boostable and well-regulated motor DC-link voltage can be established from the mains with PFC. Conversely, the stored kinetic energy can be recovered to the mains during regenerative braking operation. Next, for some specific applications without regenerative braking, a simple three-phase single-switch boost SMR is designed and implemented. Only one full-rated switch is subject to having lower line drawn power quality and slightly larger derating. Finally, an active front-end with active power filter (APF) assisted three-phase single-switch boost SMR is developed. Thanks to the inherent ability possessed by APF, good line drawn power quality is achieved. Moreover, the regenerative braking can also be accomplished. The three-phase inverter with lower rating compared to those of H-bridge SMR can be used for constructing the APF.