We present an analytical method for the calculation of cogging torque in surface permanent-magnet (PM) motors. The cogging torque is calculated by integrating the Maxwell stress tensor inside the air gap. The stator design techniques are applied to reduce the cogging to More
We present an analytical method for the calculation of cogging torque in surface permanent-magnet (PM) motors. The cogging torque is calculated by integrating the Maxwell stress tensor inside the air gap. The stator design techniques are applied to reduce the cogging torque in SPM motors. The used techniques are stator dummy slots, teeth pairing and stator slot skewing. The direct search method is used to find the optimum geometry in the mentioned methods. Finally, the validity of the proposed model and the obtained results are verified with Finite Element Analysis.
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In the presented work an analytical model is developed for the pole-shifting method in the surface-mounted PM machine at no-load condition. The machine cogging torque and the harmonic spectrum of the air gap flux density are most no-load indexes of the machine performan More
In the presented work an analytical model is developed for the pole-shifting method in the surface-mounted PM machine at no-load condition. The machine cogging torque and the harmonic spectrum of the air gap flux density are most no-load indexes of the machine performance. It is shown that, although, the pole-shifting reduces the machine cogging torque; it destroyed the half-odd symmetry in the PMs and produces even harmonics in the air gap flux density. The even harmonics of the air gap flux density, results in undesired torque pulsations. Using the developed analytical model and the direct search method a multi-objective optimization is carried out for the machine cogging torque and the total harmonic distortion of the air gap flux density. Since, the considered variables are not in a same unite; a normalized technique is applied. Finally, the developed model and the obtained results are verified by finite element analysis.
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