A novel DC-biased current dual PM vernier machine

In this paper, a novel electric machine having permanent magnets (PMs) in both stator and rotor parts, and fed with DC biased phase current is proposed. The innovative characteristic of the proposed machine is that it contains multiple field excitation sources including stator PM, rotor PM. and DC component in the phase current. Thus, the exciting field can be greatly strengthened. What is more, the exciting field is flexible and adjustable thanks to the variable DC component. Therefore, the proposed machine is expected to exhibit high torque density, wide constant power operation range. This paper firstly illustrates the basic operation principle, slot/pole combination equation, and the topology taking two proposed machines as an example. Then, effects of several key design parameters on machine performance are researched theoretically and by finite-element method (FEM). Finally, the electromagnetic performance including flux density, back electromotive force (EMF), torque quality of an optimized machine is analyzed.