Abstract：The impact of the edge thickness of the quasi-trapezoidal permanent magnet on cogging torque of multiphase fractional-slot concentrated full-pitch winding permanent magnet machines is investigated.The quasi-trapezoidal permanent magnet is actually the combination of the sinusoidal magnet and the injected third and fifth harmonics.The amplitudes of the magnet harmonics are determined by the edge thickness.The complex permanence model is adopted to calculate the cogging torque for faster optimization and determination of the optimal permanent magnet edge thickness.Analytical calculations of a 20-slot 22-pole external-rotor five-phase machine show that the quasi-trapezoidal permanent magnet is efficient to reduce cogging torque and the ratio of the optimal permanent magnet edge thickness to the maximum permanent magnet thickness is 0.5.The finite element analysis and experimental measurement of the cogging torque show the effectiveness of the analytical analysis and the conclusions.
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2015, Vol. 30 
