Comparison of stator DC-excited vernier reluctance machines with synchronous reluctance machines

Stator DC-excited vernier reluctance machines (DC-VRMs) are vernier reluctance machines equiped with additional DC field winding in stator to generate the exciting field, a rotating field similar to synchronous reluctance machines (SynRMs). This paper compares the electromagnetic performance of two non-PM reluctacne machines including DC-VRMs and SynRMs. First, the basic operation principle of DC-VRMs and SynRMs are briefly reviewed. Then, four machine models, two DC-VRMs and two SynRMs are designed and optimized for comparison. For a fair comparison, the phase current, current density, slot fill factor and dimensions including the stator outer diameter, air gap and stack length are designed the same. The electromagnetic performance including flux density, torque quality, overload capacity, power factor and losses are compared in detail.