Analysis and prototyping of a low-speed small scale permanent magnet generator for wind power applications

Many companies engaged in wind generator development are investigating permanent magnet generators (PMG) mainly because of higher efficiency over a broad range of wind speed and reduced costs of maintenance. One important parameter of PM generators is the primary magnetic flux that has certain influence to no load voltage of the machine. Thus, needs for efficient calculation methods for primary magnetic field is required. Finite element method is one of the most common and efficient way to analyze the magnetic flux of the machine. But on the other hand it is relatively complicated calculation method and it might be incomprehensible. Analytic calculation or calculations based on reluctance network are comprehensive and suitable for engineers-designers. This paper deals with the primary magnetic field analysis and basic winding calculations by an example of 54 slots and 20 poles PM synchronous generator. Modeling of the primary magnetic field distribution by the finite element method in software FEMM is described. Results from the analytic calculations and the finite element method are compared with experimental data of PM prototype generator study.