Analysis of a stand-alone permanent-magnet synchronous generator using a time-stepping coupled field-circuit method

The performance analysis of a stand-alone permanent-magnet synchronous generator with inset rotor using a coupled-circuit, time-stepping, two-dimensional finite-element method is described. The direct-coupled field-circuit method enables the instantaneous values of the field and circuit variables to be solved simultaneously, without having to evaluate the synchronous reactances and the load angle. Magnetic saturation is accounted for by considering the flux densities in the elements of the field solution region. Besides the load characteristics, the coupled field-circuit solution also yields other useful machine information including the flux plots, components of the air-gap flux density, and the waveforms of voltages and currents. The flux plots obtained clearly demonstrate the effect of armature current on the interpolar flux that helps to improve the voltage regulation. Good agreement between the computed and experimental results has been obtained on a 2.5 kVA prototype generator.