Cogging torque prediction by superposition of torque due to pole transition over slot

Theoretically, the layout of fractional pitch permanent magnet motors should ensure the cancellation of most cogging torque harmonics. In reality, manufacturing errors lead to incomplete cancellation and higher than expected cogging torque. Two potential manufacturing errors are the variation in angle between successive magnets and the strength of the magnets.To determine the sensitivity of cogging torque to magnet strength and placement, a superposition technique is used. This technique is validated by first demonstrating that the total cogging torque can be reconstructed by summing offset versions of the torque from experimentally determined single-magnet/singleslot interactions.Following this validation, Monte Carlo simulations are conducted to statistically determine the sensitivity of cogging torque to magnet placement and strength errors. It is demonstrated that the mean RMS cogging torque increases by 4 % for every degree increase in magnet placement standard deviation and by 0.06% for every 1% increase in magnet strength standard deviation.

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“…One way of ensuring that two magnets are used is to determine the torque due to one pole pair as is done in [10].…”

Section: B Superpositon Techniquesmentioning

confidence: 99%

Superposition techniques for analyzing cogging torque sensitivity to manufacturing errors in fractional pitch PMSM

Heins

Thiele

2011

IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society

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“…Fig. 8 presents the tangential and radial non-zero order vibrations, where the rotor exhibits the balanced and higher order elliptical modes for (l s , n)¼ (3,5) because parameters are satisfied with l s N s À n¼ q 1 N m and l s N s þna q 2 N m , translational and bending modes for (1, 1) because l s N s Àn aq 1 N m and l s N s þn ¼q 2 N m , and again the balanced and higher order elliptical modes for (8,16) due to l s N s Àn ¼q 1 N m and l s N s þn ¼q 2 N m . According to the analytical predictions, the forward traveling, backward traveling, and combined vibrations can be excited respectively for the three cases.…”

Section: Relative Position Effectmentioning

confidence: 99%

“…6 presents the tangential and radial vibrations for non-zero order vibration, including three cases: (l s , n)¼ (3,5), (1,1), and (8,16). Their vibrations are respectively satisfied with: (1) l s N s À n¼q 1 N m and l s N s þnaq 2 N m ; (2) l s N s Ànaq 1 N m and l s N s þn¼ q 2 N m , and (3) l s N s Àn¼ q 1 N m and l s N s þn¼q 2 N m .…”

Section: Non-zero Order Vibrationmentioning

confidence: 99%

Magnetically induced rotor vibration in dual-stator permanent magnet motors

Xie

Wang

et al. 2015

Journal of Sound and Vibration

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“…Besides, other scholars analysed the cogging torque by the coenergy method [14][15][16]. In [17,18], Liu et al and Zhu et al apply the superposition and synthesis methods to calculate cogging torque. The basic principle is that the resultant cogging torque can be obtained through superposition or synthesis of the cogging torque generated by a single slot or by a single pole transition model.…”

Section: Introductionmentioning

confidence: 99%

Cogging torque minimisation in FSPM machines by right‐angle‐based tooth chamfering technique

Zhu

Wang

2018

IET Electric Power Applications

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Cogging torque in flux-switching permanent magnet (FSPM) machines dominates the whole torque ripples due to its special doubly salient structure and high air-gap PM flux density. In this study, the chamfering method of right angles is utilised in both stator and rotor sides of FSPM machines to suppress the cogging torque. First, an analytical expression of cogging torque, taking the influence of the introduced right angles into consideration, is derived. On the basis of the derived model, the optimal dimensions of right angles are obtained and verified by both finite element analysis and experiments. Besides, the impacts of the proposed technique on phase electro-motive force and electromagnetic torque are also evaluated. The predicted results indicate that the proposed technique can significantly reduce cogging torque in FSPM machines with negligible reduction of average torque.

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Cogging torque prediction by superposition of torque due to pole transition over slot

Cited by 15 publications

References 6 publications

Superposition techniques for analyzing cogging torque sensitivity to manufacturing errors in fractional pitch PMSM

Superposition techniques for analyzing cogging torque sensitivity to manufacturing errors in fractional pitch PMSM

Magnetically induced rotor vibration in dual-stator permanent magnet motors

Cogging torque minimisation in FSPM machines by right‐angle‐based tooth chamfering technique

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