Stator/rotor slot and winding pole pair combinations of DC biased sinusoidal vernier reluctance machines

The recent novel DC biased sinusoidal current reluctance machines (DC-biased VRMs) are similar to switched reluctance machines (SRMs) in terms of structure, as they both adopt the doubly salient structure and concentrated windings. However, the special characteristic of DC-biased VRMs is that their phase currents have both DC current and AC current. Therefore, it can be inferred that the vibration and noise can be much smaller than SRMs as the phase current waveform is smooth. Besides, compared with variable flux reluctance machines with specialized field windings, DC-biased VRMs exhibit better performance such as fewer copper loss and higher torque density. In this paper, the stator/rotor slot combinations and armature winding configurations with different pole pairs of the DC-biased VRMs are deeply investigated. Firstly, relationships among stator/rotor slots and armature winding pole pairs are given based on the working principles. Then, several feasible stator/rotor slot combinations are obtained, and the electromagnetic performances are compared by the finite element analysis (FEA). The results show that the 8-rotor-slot, 5 armature pole pair machine exhibits highest torque in rated load, but with highest torque density, the 10-rotor-slot, 4-armature pole pair machine shows highest torque in over load condition, and the 12/11 and 12/13 machine presents the minimum pulsation torque.