Abstract
This thesis presents the development of a digital signal processor (DSP) based position sensorless switched reluctance motor (SRM) drive with buck-boost switch-mode rectifier (SMR) front-end. First, for comprehending the key issues in making the SRM driving control, a standard SRM drive is designed, implemented and evaluated. Satisfactory operating characteristics are obtained via properly treating its power circuit, sensing scheme, current controlled PWM switching scheme and dynamic control. Next, to let the developed SRM drive fed from mains have improved operating performance, a buck-boost SMR front-end is employed to establish boostable and well-regulated DC-link voltage with good AC input power quality. The SMRs under both discontinuous conduction mode (DCM) and continuous conduction mode (CCM) operations are comparatively evaluated their performances. The SRM drive and SMR front-end are realized in a common DSP to achieve the miniaturization of control environment. Finally, a novel SRM position sensorless control approach based on narrow pulse voltage injection is developed. The voltage pulses with suited frequency and duration are injected into the unenergized phase winding via the embedded DSP PWM channel. The resulted amplitude modulated winding currents are sensed and signal processed to yield an observed Hall signal. In sensorless control operation, the motor is initially started in stepping motor mode. As the speed is established to a reasonably high value, the operation is changed to switched-reluctance motor mode using the observed Hall signal. And the speed feedback control is conducted using the observed speed, which is obtained from the sensed four winding currents. Moreover, the commutation advanced shift is applied to yield the improved torque generating capability, i.e., the enhanced torque-per-ampere characteristics. The experimental evaluation shows that the developed position sensorless controlled SRM drive possesses good driving performance under a reasonably wide speed range.