Analytic calculation of the magnetic field in PM machines

The aim of the research project this paper arises from, is the development of a high-speed, high-efficiency generator system for use in series-hybrid vehicles. This paper describes an analytic method for the two-dimensional calculation of the magnetic field in the cylindrical air gap of the permanent-magnet generator. Further, it introduces a method to visualize this field, namely by plotting the lines of constant magnetic vector potential. To show that the calculated magnetic field may form the basis of a machine model, the voltage equations are derived. The proposed analytic method gives insight into the relations between dimensions and parameters of the machine, which is important when optimizing the design.