Application of permanent-magnet reluctance to minimise torque pulsation in single-phase synchronous motors

A theory of applying permanent-magnet reluctance torque to suppress pulsating torque in single-phase synchronous motors is described. Solution sets exist for eliminating pulsating torque at all nominal loads which are equal to, or less than, the amplitude of the reluctance torque. A selfstarting experimental motor having closed slots is described, and is shown to implement this theory effectively. Load testing shows that torque pulsation reduces to a minimum as the load moves to the nominal value. Application of these constant-torque solution sets to this closed-slot topology is described, showing characteristics. Selected solutions allow a sufficiently high ratio of pullout to nominal power for operation from the AC mains. Applications, and means for starting and controlling the closed-slot motor, and other topologies are described.