Permanent Magnet Machines: Asychronous Operation

The permanent magnet motor operating at subsynchronous speeds, as during run-up, is treated with particular emphasis placed on the role that magnet excitation plays. The torque, during run-up, is separated into components called the "cage torque", the "magnet torque" and pulsating components of double-slip-frequency and single-slip-frequency. Equations for calculation of these torques are derived and a comparision of the relative magnitude is given.