On the use of dimensioning equations for surface permanent magnet machines

Surface permanent magnet (SPM) machines are widely used in a vast variety of industrial, domestic and vehicular applications. In the engineering practice, it is useful to adopt dimensioning equations to quickly predict their size, weight and production cost based on few specification data. In this paper, a possible sizing equation is considered showing how it may bring to significantly different accuracy levels depending on how the no-load air-gap flux is modeled. A comparison is proposed of the results which can be obtained with different no-load flux models taking into account a high-speed SPM generator as a study case.