Shielding the end windings to reduce bearing currents

Vostrov, Konstantin; Pyrhönen, Juha; Ahola, Jero

doi:10.1109/icem49940.2020.9270673

Cited by 11 publications

(5 citation statements)

References 26 publications

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“…Figure 5 shows the 15-kW machine in which the extended electrode concept is applied. Extended grounded electrodes create an effect of a shielding structure for the end-winding parts, similar to that proposed in [9]. At the same time, they are not a separately mounted structure and represent a single whole with the core-mounted shielding system.…”

Section: Laboratory Experimentsmentioning

confidence: 98%

“…There are four types in total. All the types are described in detail both in our papers [9] - [11] and in the publications of other authors [12] - [15]. A summary table of the given types of parasitic currents is given in Table I.…”

Section: Introductionmentioning

confidence: 99%

“…A summary table of the given types of parasitic currents is given in Table I. We see no reason to give a detailed description of these types of parasitic currents or show the current paths since an exhaustive description has been given and illustrated many times, for example, in [9], or in IEC technical specification [16]. In short, those types are the following.…”

Section: Introductionmentioning

confidence: 99%

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On the Application of Extended Grounded Slot Electrodes to Reduce Noncirculating Bearing Currents

Vostrov

Pyrhönen

Niemelä

et al. 2023

IEEE Trans. Ind. Electron.

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Power-electronic-converter-induced motor bearing currents are a widespread problem in the field of electrical drives. Parasitic capacitances between the electrical machine's parts provide a path for leakage currents, which finally harm metallic ball bearings. Remembering that end-windings have a significant contribution in building up stray capacitances, a countermeasure affecting both the lamination stack and end winding areas is needed. This paper focuses on a countermeasure against the non-circulating bearing currents in the cluster of solutions at the motor side. Electrostatic shielding approach, which is a known principle to reduce capacitive couplings, is applied in electrical machines every now and then. In this work, the principle of slot-embedded grounded electrodes is extended to cover also the end-windings. Thus, the electrodes provide a better shaft-to-ground voltage mitigating effect compared to the case where electrodes are applied only in the lamination stack area. The feasibility and effectiveness of such a countermeasure are investigated. Different options in terms of scaling of both the machine size and diameter of the electrodes were analyzed and corresponding conclusions were pointed out.

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Section: Laboratory Experimentsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the Application of Extended Grounded Slot Electrodes to Reduce Noncirculating Bearing Currents

Vostrov

Pyrhönen

Niemelä

et al. 2023

IEEE Trans. Ind. Electron.

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“…As suggested in [23], the utilization of electrostatic shields, which affect both the core area and the end windings, provides an opportunity to reduce the bearing voltage by 100%. Special end windings shields, such as [47], used in parallel with the method presented here, are expected to give the maximum possible bearing voltage reduction.…”

Section: ) Verification With the Bearing Voltage To The Commonmode Voltage Ratiomentioning

confidence: 99%

Mitigation of Inverter-Induced Noncirculating Bearing Currents by Introducing Grounded Electrodes into Stator Slot Openings

Vostrov

Pyrhönen

Lindh

et al. 2021

IEEE Trans. Ind. Electron.

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Modern converter-supplied AC motors are exposed to bearing currents. Despite extensive research and development, the industry still does not have a final solution with acceptable cost and high efficiency. This paper focuses on capacitive bearing currents. After a brief explanation of the phenomenon, an unconventional approach for effective mitigation of the capacitive bearing currents is proposed. The approach suggests using grounded electrodes in the slot openings to reduce the stator-winding-to-rotor-core capacitance and thereby the bearing currents. Different electrode diameters are considered and evaluated by a FEM analysis. The results are verified by laboratory tests. The bearing voltage ratios of the original and modified induction motor are compared. Index Terms-Ball bearings, electrical discharge machining bearing currents, electrical machines, finite element analysis, induction machines, variable speed drives.

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“…One of them is to increase the distance between the stator windings located in the slots and the rotor surface [30]. Solutions based on the introduction of a grounded shield into the slot opening space [31,32] and around the stator end-winding [33][34][35] are highly effective. These shields are implemented in the form of, among other things, tapes of conductive material or copper wires.…”

mentioning

confidence: 99%

Influence of the Shielding Winding on the Bearing Voltage in a Permanent Magnet Synchronous Machine

2022

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This article presents selected methods of limiting the bearing voltages of synchronous machines with permanent magnets supplied from power electronic converters. The authors analyzed methods based on the use of various shielding windings placed in slot wedges and mounted in the stator end-winding region. The values of the parasitic capacitances of the machine, on which the levels of bearing voltages depend, were determined using the finite element method. Three-dimensional simulation models were used for the calculations. The analysis of the influence of the shielding windings on the bearing voltage waveforms was conducted on the basis of circuit models with two- and three-level converters. The obtained calculation results indicate a high potential in limiting bearing voltages.

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Shielding the end windings to reduce bearing currents

Cited by 11 publications

References 26 publications

On the Application of Extended Grounded Slot Electrodes to Reduce Noncirculating Bearing Currents

On the Application of Extended Grounded Slot Electrodes to Reduce Noncirculating Bearing Currents

Mitigation of Inverter-Induced Noncirculating Bearing Currents by Introducing Grounded Electrodes into Stator Slot Openings

Influence of the Shielding Winding on the Bearing Voltage in a Permanent Magnet Synchronous Machine

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