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Analysis of Cogging Torque in Surface-Mounted Permanent Magnet Machines with Shaped Magnets

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Third Harmonic Utilization in Permanent Magnet Machines

Abstract

The third harmonic can be injected into the Sinusoidal shaped permanent magnets (PM) to improve the average torque in three-phase surface-mounted PM (SPM) machines without deteriorating the torque ripple caused by back-EMFs harmonics. However, the influence of the injected third harmonic on the cogging torque is uncertain. The aim of this chapter is to analytically derive the cogging torque in SPM machines equipped with Sinusoidal shaped (Sine-shaped) and Sinusoidal shaped with third harmonic injected (Sine+3rd-shaped) PMs, which are optimized to obtain sinusoidal and sinusoidal with third harmonic airgap flux density distributions, respectively. It is found that the cogging torque of the SPM machines with Sine-shaped PMs is negligibly small. The Sine+3rd-shaped PM can increase the amplitude of the cogging torque for the specific three-phase SPM machines with the number of slots per pole per phase (spp) equal to 0.25, 0.5 and 1. Finite element analyses are carried out on 6-slot/8-pole (spp = 0.25), 12-slot/8-pole (spp = 0.5), 24-slot/8-pole (spp = 1) and 12-slot/10-pole (spp = 0.4) SPM machines with shaped PMs to verify the analyses. A SPM machine with Sine+3rd-shaped PMs is prototyped and tested for validation.

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Correspondence to Kai Wang .

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Wang, K., Zhu, ZQ. (2019). Analysis of Cogging Torque in Surface-Mounted Permanent Magnet Machines with Shaped Magnets. In: Third Harmonic Utilization in Permanent Magnet Machines. Springer, Singapore. https://doi.org/10.1007/978-981-13-0629-7_7

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  • DOI: https://doi.org/10.1007/978-981-13-0629-7_7

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  • Publisher Name: Springer, Singapore

  • Print ISBN: 978-981-13-0628-0

  • Online ISBN: 978-981-13-0629-7

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