Reduction of cogging torque in interior-magnet brushless machines

Zhu, Z. Q.; Ruangsinchaiwanich, S.; Schofield, N.; Howe, D.

doi:10.1109/tmag.2003.816733

Cited by 99 publications

(25 citation statements)

References 7 publications

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“…In these two equations, if we consider the orthogonal property of trigonometric function, then, the equation (3) may be expressed by: (6) where N L is the least common multiple (LCM) of the number of slots and pair-poles. Finally the equation (2) may be expressed by: (7) In this way, the magnetic flux and stored energy vary with different rotor angle positions.…”

Section: Cogging Torque Theorymentioning

confidence: 99%

“…− The use of a fractional number of slots per pole per phase [1,13,14]; − The use of auxiliary slots or teeth [7]; − Magnet segmentation [6]; − The optimization of the sizes and pole-arc of magnets [2,5,8,12] − The optimization of the magnet displacement and shaping [3][4][5][6][7][8][9][10][11][12][13][14][15] − The skewing of stator slots or magnets [1,2,11]; − Changing the width of the opening stator slot [9,10], etc.…”

Section: Introductionmentioning

confidence: 99%

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Cogging Torque Reduction in Permanent-Magnet Brushless Generators for Small Wind Turbines

Chung¹,

You²

2015

Journal of Magnetics

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We present the design optimization of the magnetic pole and slot design options that minimize the cogging torque of permanent-magnet (PM) brushless generators for small wind turbine generators. Most small windturbines use direct-driven PM generators which have the characteristics of low speed and high efficiency. Small wind-turbines are usually self-starting and require very simple controls. The cogging torque is an inherent characteristic of PM generators, and is mainly caused by the generator's geometry. The inherent the cogging torque can cause problems during turbine start-up and cut-in in order to start softly and to run a power generator even when there is little wind power during turbine start-up. Thus, to improve the operation of small turbines, it is important to minimize the cogging torque. To determine the effects of the cogging torque reductions, we adjust the slot opening width, slot skewing, mounting method of magnets, magnet shape, and the opening and combinations of different numbers of slots per pole. Of these different methods, we combine the methods and optimized the design variables for the most significant design options affecting the cogging torque. Finally, we apply to the target design model and compare FEA simulation and measured results to validate the design optimization.

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Section: Cogging Torque Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cogging Torque Reduction in Permanent-Magnet Brushless Generators for Small Wind Turbines

Chung¹,

You²

2015

Journal of Magnetics

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“…While cogging torque generated by the interaction of rotor magnetic flux and angular variation in the stator magnetic reluctance, ripple torque is the result of the interaction of current magnetomotive forces(mmf's) with the rotor magnet flux distribution, which is the dominant part of the pulsating torque. There are a lot of methods to weaken the cogging torque [2]- [5]. To minimize the torque ripple, we usually use these ways, such as slot skewing, pole shape optimization and so on [6]- [7].…”

Section: Introductionmentioning

confidence: 99%

A practical method for reducing torque ripple of interior permanent magnet machine by optimizing rotor topology

Wang

Guo

Wang

2013

2013 International Conference on Electrical Machines and Systems (ICEMS)

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This paper discusses the reduction of torque ripple in interior permanent magnet (IPM) machine. We find that the torque ripple can be minimized by optimizing two key parameters of rotor based on the principle of virtual displacement. The effectiveness of the proposed method is proved by the analytical and finite element analysis(FEA) results. Finally, a prototype was built, and the test result was compared with predicted torque waveform as a mean of confirming the model accuracy.

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“…OMPARING to surface-mounted permanent magnet machines, the interior permanent magnet machines (IPM machines) have higher torque density due to the saliency torque component and require lower magnetic and iron materials [1]. Furthermore, since the permanent magnets are inserted into the rotor, the permanent magnets have higher demagnetization withstand capability.…”

Section: Introductionmentioning

confidence: 99%

Design of double salient interior permanent magnet machine based on mutually coupled reluctance machine for increasing the torque density and flux-weakening capability

Ojeda

Hoang

et al. 2010

2010 IEEE International Symposium on Industrial Electronics

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This paper presents a novel structure of double salient interior permanent magnet machine (DSIPM machine) based on mutually coupled switched reluctance machine (MCSRM). Due to its salient rotor structure, the DSIPM machine can have less magnetic and iron materials as well as higher dynamic response than conventional IPM machines. The comparison of electromagnetic performances in terms of self and mutual inductances, d-axis and q-axis inductances, cogging torque, reluctance torque, total torque, torque ripple coefficient and flux-weakening capability between the DSIPM machine 6/8 and the DSIPM machine 12/8 has been realized. The numerical results based on Finite Element 2D shows that due to its much lower cogging torque and higher reluctance torque, the DSIPM machine 12/8 can produce higher total average torque than the DSIPM 6/8 at all phase current range. Furthermore, at low phase currents, the torque ripple of the DSIPM machine 12/8 is lower than that of the DSIPM machine 6/8, while at high phase currents, the torque ripples of these two machines are similar. Comparing to MCSRM, the DSIPM machines can produce higher average torque with lower torque ripple. Moreover, due to their high d-axis inductances, the two DSIPM machines can have theoretically ''infinite'' flux-weakening capability with relatively lower short-circuit currents.

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Reduction of cogging torque in interior-magnet brushless machines

Cited by 99 publications

References 7 publications

Cogging Torque Reduction in Permanent-Magnet Brushless Generators for Small Wind Turbines

Cogging Torque Reduction in Permanent-Magnet Brushless Generators for Small Wind Turbines

A practical method for reducing torque ripple of interior permanent magnet machine by optimizing rotor topology

Design of double salient interior permanent magnet machine based on mutually coupled reluctance machine for increasing the torque density and flux-weakening capability

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