FEA-based calculation of load characteristics of stand-alone PM generators with inner or outer rotor constructions

This paper deals with the field-circuit method developed for quick computation of load characteristics of stand-alone permanent magnet synchronous generators (PMSGs) with different rotor structures. The method is based on the so-called loading method, used widely for calculation of electromechanical characteristics of permanent magnet synchronous motors. In the developed calculation algorithm, the circuit equations of PM synchronous machine are adopted so to represent the stand-alone generative mode of operation with the assumption that the load is purely of R or R-L type. The iterative procedure is used to find the correct magnitude of output current phasor and then magnitude and phase angle of output voltage phasor for a given load conditions. It is assumed in the algorithm that the load power factor cosφ is known in advance and the load characteristics are calculated for in advance given range of phase angles of output current phasor. The results of load characteristic calculations are compared to the laboratory test results. The field-circuit method described in the paper can be used for prediction of load characteristics of PMSGs with surface mounted, inset or interior mounted permanent magnets and with inner or outer rotors.