Rare-earth-less motor with field poles excited by space harmonics

This paper describes a synchronous motor in which space harmonics power is utilized for field magnetization instead of permanent magnets. The stator has a concentrated winding structure, and the rotor has two sorts of windings, i.e., an induction pole (I-pole) winding that retrieves mainly the third space harmonics and an excitation pole (E-pole) winding for the field magnetization. The both coils are connected via a diode rectifying circuit. By utilizing the E-pole torque magnetized with self-excitation, permanent magnet volume of the proposed motor is reduced by 81.4 %, compared with the benchmark IPM motor.