Induced voltage harmonic reduction of PM cylindrical machines

In a previous paper, the authors (1989) introduced a simple graphical method that allows the designer to refine a given design by modifying the magnet shape and dimensions to minimize key harmonic components that exist in that design. In this work, a more precise two-dimensional model of the magnetic circuit, which has been analytically and experimentally validated, is used in conjunction with this method. In addition to improving accuracy, the model makes it possible to explore the impact of other design factors, such as the number of poles and the direction of magnetization (parallel versus radial), on harmonic content and utilize them, as added degrees of freedom, in optimizing the machine design. A brief description of the model and of the mathematical approach used is given, together with the final expressions for the flux density waveform at the stator surface for both parallel and radial magnetization. The results are compared with those obtained by finite element analysis.<>