Methods to reduce cogging torque of permanent magnet synchronous generator used in wind power plants

Ose-Zala, Baiba; Pugachov, Vladislav

doi:10.5755/j01.eie.23.1.12714

Cited by 9 publications

(6 citation statements)

References 18 publications

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“…Increasing interest in the efficiency of electric machinery and reducing maintenance costs is making the use of permanent magnet synchronous generators (PMSGs) more common. PMSGs combine high efficiency with low maintenance and a high power density [1], factors that make them extremely attractive for use in renewable energy applications are, such as wind [2], wave power [3], and tidal power [4], or electrical mobility applications [5] and, in general, in uses where they must act as a motor or generator. Furthermore, in renewable energy applications, PMSGs allow direct-drive configurations, making the use of a gearbox unnecessary or reducing the number of gearbox stages, which decreases the overall generator volume and improves its efficiency [6].…”

Section: Introductionmentioning

confidence: 99%

“…There are several methods to reduce cogging torque in the PMSG design phase. The most used is skewing, which consists of preventing the stator teeth and the magnets from becoming aligned by either turning the stator teeth [6,12] or the rotor's permanent magnets [1,2,13]. The required skew angle to largely cancel out the effect of the interactions between the PMs and the slots depends on how many slots and poles the machine has.…”

Section: Introductionmentioning

confidence: 99%

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Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

García-Gracia

Romero

Ciudad³

et al. 2018

Energies

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Cogging torque is a pulsating, parasitic, and undesired torque ripple intrinsic of the design of a permanent magnet synchronous generator (PMSG), which should be minimized due to its adverse effects: vibration and noise. In addition, as aerodynamic power is low during start-up at low wind speeds in small wind energy systems, the cogging torque must be as low as possible to achieve a low cut-in speed. A novel mitigation technique using compound pre-slotting, based on a combination of magnetic and non-magnetic materials, is investigated. The finite element technique is used to calculate the cogging torque of a real PMSG design for a small wind turbine, with and without using compound pre-slotting. The results show that cogging torque can be reduced by a factor of 48% with this technique, while avoiding the main drawback of the conventional closed slot technique: the reduction of induced voltage due to leakage flux between stator teeth. Furthermore, through a combination of pre-slotting and other cogging torque optimization techniques, cogging torque can be reduced by 84% for a given design.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

García-Gracia

Romero

Ciudad³

et al. 2018

Energies

View full text Add to dashboard Cite

show abstract

“…Increasing interest in the efficiency of electric machinery and reducing maintenance costs is making the use of permanent magnet synchronous generators (PMSGs) more common. PMSGs combine high efficiency with low maintenance and a high power density [1], factors that make them extremely attractive for use in renewable energy applications, such as wind [2], wave power [3] and tidal power [4], or electrical mobility applications [5] and, in general, in uses where they must act as a motor or generator. Furthermore, in renewable energy applications, PMSGs allow direct-drive configurations, making the use of gearbox unnecessary or reducing the number of gearbox stages, which decreases the overall generator volume and improves its efficiency [6].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

García-Gracia¹,

Romero²,

Ciudad³

et al. 2018

Preprint

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Cogging torque is a pulsating, parasitic and undesired torque ripple intrinsic of the design of a permanent magnet synchronous generator (PMSG), which should be minimized due to its adverse effects: vibration and noise. In addition, as aerodynamic power is low during start-up at low wind speeds in small wind energy systems, the cogging torque must be as low as possible to achieve a low cut-in speed. A novel mitigation technique using compound pre-slotting, based on a combination of magnetic and non-magnetic materials, is investigated. The finite element technique is used to calculate the cogging torque of a real PMSG design for a small wind turbine, with and without using compound pre-slotting. The results show that cogging torque can be reduced by a factor of 48% with this technique, while avoiding the main drawback of the conventional pre-slotting technique: the reduction of induced voltage due to leakage flux between stator teeth. Furthermore, through a combination of pre-slotting and other cogging torque optimization techniques, 84%, cogging torque can be eliminated for a given design.

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“…They have shown that force ripple is reduced by 60.65%, 80%, and 90% in 4-pole, 6-pole, and 8-pole motors, respectively. 6 Ose-Zala and Pugachov 7 have investigated the effects of PM shifting technique and number of PM on the cogging torque of a permanent magnet synchronous generator (PMSG). In addition, the optimum values of PM shifting angle and number of PM have been determined.…”

mentioning

confidence: 99%

Magnet shifting for back EMF improvement and torque ripple reduction of a TORUS‐type nonslotted axial flux permanent magnet machine

Mirzahosseini

Darabi

Assili

2019

Int Trans Electr Energ Syst

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Summary Permanent magnet (PM) shifting method is one of the ways to improve performance characteristics of PM machines. In this paper, PM shifting method is employed to reduce total harmonic distortion (THD) of the back EMF and torque ripple of a TORUS type nonslotted axial flux permanent magnet (TORUS NS‐AFPM) machine. To fulfill this goal, a formula for calculating back EMF waveform of the machine with shifted PMs is proposed. A 3.7 kW, 1400 rpm TORUS NS‐AFPM machine is selected as case study machine and the accuracy of the proposed formula is confirmed with the help of three‐dimensional finite element method (3‐D FEM). Then by using proposed formula, the effect of PM shifting angle on the back EMF waveform of the machine is investigated. In addition, the case study machine is fabricated and back EMF waveform of the machine with different value of PM shifting angle is analyzed using experimental results. With the help of proposed formula and 3‐D FEM the effect of PM shifting angle on the torque ripple of the machine is studied. In addition, a procedure for calculating optimum value of PM shifting angle is proposed. The obtained results show the effectiveness of the PM shifting method on improving machine back EMF waveform and torque ripple.

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Methods to reduce cogging torque of permanent magnet synchronous generator used in wind power plants

Cited by 9 publications

References 18 publications

Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

Cogging Torque Reduction Based on a New Pre-Slot Technique for a Small Wind Generator

Magnet shifting for back EMF improvement and torque ripple reduction of a TORUS‐type nonslotted axial flux permanent magnet machine

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