Analysis of the steady-state components in a balanced single-phase synchronous reluctance motor with a running capacitor

Torque pulsations arising from rotor saliency and stator winding imbalance degrade the performance of single-phase reluctance motors. This paper examines different components of torque produced by such a motor and studies their individual dependencies on machine operational indices in the steady state. The torque expressions are derived in component parts by d-q harmonic balance as functions of load angle and auxiliary winding capacitor value from which performance is assessed. By adjusting the capacitor value using established conditions for balance, improved drive performance as a 2-phase motor is realized. Simple test results were used to assess the validity of the harmonic balance model and a good agreement is observed. Torque pulsations due to stator winding imbalance were reduced while that due to rotor saliency remained unaffected as expected. The improvement in efficiency under balanced conditions, permit the motor to support a higher load torque than rated.