Low harmonics high efficiency permanent magnet synchronous machines based on non-uniform magnet slot

This paper proposed a novel magnet circuit to improve flux density waveform of air gap and efficiency. The sencond air gap length is variable when non-uniform magnet slot and uniform magnets are used in permanent magnet synchronous machines(PMSM), so magnetomotive force and flux density in first air gap are not flat wave. The flux density wavform of air gap will be improved when size of non-uniform magnet slot changed.This paper analyzed harmonics components of no-load flux density of air gap on a PMSM sample of 1.5kW, 4P based on Ansoft. Simulation results showed that the Total Harmonic Distortion (THD) of no-load flux density of air gap of PMSM reduced distinctly based on non-uniform magnet slot. Test results verified validity of non-uniform magnet slot. When non-uniform magnet slot is used in PMSM, the THD of no-load flux density of air gap of sample reduced by about 18.93%, and efficiency of sample improved by about 1%.