Development of SRM for spindle motor system

This paper presents the design and characteristics of a switched reluctance motor (SRM) for high-speed spindle drive applications. The SRM is highly feasible for a high speed (15000 RPM) spindle drive because of its simple rotor construction. For compatibility with conventional AC induction motor drives, the main dimensions of the SRM should be identical with those of the induction motor and a general purpose V/f inverter drive should be used. The analysis shows that the motor should have a sinusoidal inductance distribution profile with respect to the rotor position in order to produce a ripple-free torque when the motor is operated with a general purpose V/f inverter. The FEM-based design procedure of an SRM with a sinusoidal inductance distribution is described in the paper. It is also explained that, for specified main dimensions of the motor, the pole arc can be designed suitably to produce maximum torque for a sinusiodal current drive. The SRM drive is found to be more energy efficient than conventional induction motor drives normally used for this application. Satisfactory operating characteristics of the SRM for this application are also presented.