Design of a Homopolar Inductor Alternator Based on a 2-D Equivalent Model

Homopolar inductor alternator (HIA) has wide range of applications in the field of flywheel energy storage system with the merits of solid rotor structure, brushless exciting and low idling losses. While the design progress of HIA is complex and time consuming due to its three-denominational (3-D) magnetic circuit structure. To solve the above-mentioned problem, a new method to design HIA and the corresponding optimized measures are implemented. At the beginning, the method and principle of superposing the air-gap flux density are introduced. Based on it, the HIA can be equivalent to a wound-field salient pole alternator (WSPA) with two-denominational (2-D) magnetic circuit structure. The HIA is designed according to the design method of WSPA. Meanwhile, the saturation of stator shell and rotor shaft of HIA is considered in the design progress. To facilitate the design, an automatic design program using Monte Carlo search method is developed. Finally, both the effectiveness of this equivalent method and the correctness of automatic design program are validated by finite-element analysis (FEA) and corresponding experiments. The results show that the proposed method would be helpful for the design of HIA.