Slot ripples in alternator e.m.f. waves

Walker, J.H.

doi:10.1049/jiee-2.1949.0039

Cited by 8 publications

(6 citation statements)

References 0 publications

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“…An ac perturbation, I ac , in the field winding is caused by the change in permeance due to the variation in number of slots that are covered by the pole shoe and associated diverging field. This effect is well documented by [2], along with a design methodology to reduce it and consequently minimise slotting harmonics contained within the stator voltage. The finite element method is able to incorporate this by representing the field circuit with an external voltage source and series resistance.This is an expected effect the finite element correctly predicts, and is noticeable in both finite element methods.…”

Section: Comparison With Measurementmentioning

confidence: 94%

“…The total harmonic distortion of eight machines is calculated using equation 8and shown in Figure 9. The factory test results are compared with both FE simulation methods and an existing analytical design tool documented in [4], based upon work within [2]. Machines A -D are four pole 72 stator slot machines with ratings from 5 to 10 MVA whilst machines E -H are four pole 60 stator slot generators with ratings of 12 to 20 MVA.…”

Section: Comparison Of Total Harmonic Distortion (Thd)mentioning

confidence: 99%

“…The positioning of damper bars upon the rotor pole face can be used to attenuate or magnify THD harmonics. Walker's work [2], shows that for machines with an even number of stator slots the harmonics are attenuated when damper bars are offset by 0.25 of a stator slot pitch in the opposite direction on each pole. This will place any induced harmonics associated with the damper bars in antiphase so that the net harmonic effect of the damper bars is zero.…”

Section: The Effect Of Damper Bars Within Synchronous Machinesmentioning

confidence: 99%

“…These harmonics can be substantial and require a more complex computation. There have been a series of attempts to model this effect, ranging from the purely analytical methods of [2,3,4] through to hybrid finite element/analytical methods employed in [5,6,7]. Full transient solutions will provide the most accurate model, but have hitherto been avoided because, even in two dimensions, they are very slow and cumbersome.…”

Section: Introductionmentioning

confidence: 99%

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Open circuit voltage distortion in salient pole synchronous generators with damper windings

Hargreaves¹,

Mecrow²,

Hall³

2010

5th IET International Conference on Power Electronics, Machines and Drives (PEMD 2010)

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This paper examines efficient methods for the calculation of open circuit voltage distortion in salient pole synchronous generators with damper windings. It then proceeds to examine the role of damper bars in the level of distortion. The simplified finite element method employed is inclusive of eddy current effects, dynamic field current and full interaction of all MMF sources. It allows accurate total harmonic distortion values to be calculated approximately 25 to 30 times quicker than a fully rotating finite element simulation. Tests have been conducted on eight built machines and results compared to both analytical and alternative finite element methods. The proposed mehtod has an average reduction in error of 55%, compared to an existing analytical method. The presence of damper bars and their position within the pole face is examined, and shown to have a large influence over the level of total harmonic distortion produced.

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Section: Comparison With Measurementmentioning

confidence: 94%

Section: Comparison Of Total Harmonic Distortion (Thd)mentioning

confidence: 99%

Section: The Effect Of Damper Bars Within Synchronous Machinesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Open circuit voltage distortion in salient pole synchronous generators with damper windings

Hargreaves¹,

Mecrow²,

Hall³

2010

5th IET International Conference on Power Electronics, Machines and Drives (PEMD 2010)

View full text Add to dashboard Cite

show abstract

“…A mirror asymmetry in the air-gap permeability of two adjacent poles can be used to reduce slot harmonics and disturbances in motor start-ups. This is due to anti-phase effect [65] [92].…”

Section: Damper Winding Configuration For Torque Performancementioning

confidence: 99%