Analysis of half-wave rectified brushless synchronous motor with permanent magnets

A theoretical study of a half-wave rectified brushless synchronous motor is described. The field of the new type of brushless synchronous motor is excited not only by the field current obtained by rectifying the EMF in the field winding with a diode, but also by permanent magnets. The EMF is induced by the MMF which rotates at synchronous speed and pulsates at bias frequency. The characteristic equations are derived, and the effects of modulation function waveform and excitation method on the performance characteristics are investigated. The calculated results of the performance characteristics agree well with experimental results. It is confirmed from the theoretical study that the triangular wave is most advantageous for the modulation function and that the use of permanent magnet excitation improves the power factor.<>