Examination of an axial-gap generator with ferrite permanent magnets realizing miniaturization and high output power of engine generators

In general engine generators, the engine and generator are separate units connected by a mechanical coupling. This tends to increase the package size of general engine generators. In this paper, we are able to achieve miniaturization and high output power of the generator by adopting an axial-gap structure through using ferrite permanent magnets. At the same time, the package size is reduced dramatically by integrating the axial-gap generator into the engine. This paper also discusses methods for reducing the eddy current losses that occur in the windings due to the open-slot structure of the stator core and occur in the rotor support component. By using results from three-dimensional finite element analysis, we show that the eddy current loss that occurs in the windings is reduced by using appropriate methods to wind the coils with rectangular wires. In addition, the eddy current loss that occurs in the rotor support component is decreased by appropriately selecting the material and changing the shape of the component. Experimental results show that the studied structure is effective for realizing miniaturization and high output power of the generator, as well as for decreasing the package size of the engine generator.