Electromagnetic Torque of Reluctance Machines with Star-Shaped Stator and Rotor in the Context of Polyharmonic Current in Winding

This study reviewed the structure of a reluctance machine with a star-shaped stator and rotor. The authors analyzed the electromagnetic torque of a machine when powering the stator winding with polyharmonic currents and determined a related formula. The equations for energy characteristics of reluctance and induction machines were established. It was found that in electric machines when inductor ripple is sinusoidal and phase winding is supplied with polyharmonic currents, DC component of electromagnetic torque is produced by harmonic components number 0.2 and 1. When inductor ripple in winding is sinusoidal, higher current harmonics in armature winding do not produce a DC component of electromagnetic torque when the rotor is spinning but cause it to ripple. It is stated that more than two phases are necessary to reduce electromagnetic torque ripple in reluctance machines and more than three phases are required for induction machines. It was found that the induction machines are more capable of achieving required energy characteristics compared with reluctance machines.