Comparative study of new axial field permanent magnet hybrid excitation machines

Abstract

Hybrid excitation synchronous machines (HESMs) are permanent magnet machines which allow the control of the air-gap flux density. In this study, three new axial field HESM structures, each having two rotors and one stator, are proposed. The operation principles of these machines, considering weakening or supporting the air-gap flux density, are described. The magnetostatic and transient analyses of the proposed models have been carried out by using finite element method. To have reliable analysis results, the stator length and input and output diameters of the models have been chosen to be identical. Results are compared in terms of efficiency, power density and range of flux control between each other and another axial field HESM in the literature. In conclusion, the proposed HESM models demonstrate satisfactory performance for the generator mode and they are suitable for wind energy applications. Furthermore, because of their field weakening operation ability they can be used as motors in the vehicle industry.