The switched reluctance (SR) motor is a new form of brushless DC motor without permanent magnets, capable of low cost manufacture and a wide speed range. Because of its simplicity, ruggedness and wide speed range, it is a candidate for a broad range of applications from domestic appliances to aerospace and automotive actuators. In this thesis, two original aspects of the SR motor drive are explored. First, the application of the SR motor to a domestic food processor is explored by designing, building and testing two prototype drives. This project provided experience on the entire system design. In particular, it permitted an evaluation of the SR drive at high speed with respect to its efficiency, thermal characteristics, power density and noise level in comparison with a conventional AC series commutator motor with triac control. The second aspect of this thesis is an original investigation into the use of flux screens to improve the specific torque (torque per unit volume) of 'the switched reluctance motor. The torque of the SR motor is determined by the variation of self-inductance of the phase windings as the rotor rotates. Under dynamic operating conditions this variation can, in principle, be increased by dynamically decreasing the minimum selfinductance through the use of eddy current screens. Several configurations of screens are postulated, analyzed by finite-element techniques and tested in an experimental motor. Although the experimental results are inconclusive, this investigation introduces some interesting possibilities for future motors. The work described in this thesis was entirely sponsored by industry, and particular acknowledgement is made to Kenwood Ltd. (food processor project); Lucas (disk motor project); and the SPEED consortium (flux screen project)
