Impact of inverter drives employing fast-switching devices on form-wound AC machine stator coil stress grading

Espino-Cortés, Fermín P.; Ea, Cherney; Jayaram, S.

doi:10.1109/mei.2007.288451

Cited by 69 publications

(38 citation statements)

References 13 publications

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“…bushings or machine stators) [28], [31]. Different methods can be used to shape the electric field distribution and can be classified as follows [17], [19], [32].…”

Section: A Shielding Methodsmentioning

confidence: 99%

“…Resistive gradings (particularly with non-linear materials) are difficult to design for a wide frequency range [28], [34].…”

Section: A Shielding Methodsmentioning

confidence: 99%

“…This is critical for the grading methods using metallic electrodes (geometric, capacitive) [30]. Furthermore, the displacement current flowing in a resistive material used for field grading can also produce losses at MF [28], [33].…”

Section: A Shielding Methodsmentioning

confidence: 99%

“…The triple points, i.e. the locations at the interfaces between the insulation, the core, and the air, are particularly sensitive [19], [28], [29]. Moreover, the MF and HF (due to the switching transients) harmonics applied to the insulation further reduce the lifetime of the transformer in the presence of discharges [10], [28], [29].…”

Section: Magnetic/electric Field Analysismentioning

confidence: 99%

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Electrical shielding of MV/MF transformers subjected to high dv/dt PWM voltages

Guillod

Krismer

Kolar

2017

2017 IEEE Applied Power Electronics Conference and Exposition (APEC)

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Abstract-The introduction of Medium-Voltage (MV) SiliconCarbide (SiC) devices enables the usage of higher power converter operating voltages, switching frequencies, and commutation speeds. This implies that Medium-Frequency (MF) and High-Frequency (HF) transients are applied to passive components, and particularly to inductors and transformers. Together with the operation at medium voltage, this leads to challenging situations with respect to Common-Mode (CM) currents, parasitic resonances, insulation coordination, and EMI. The electrical field is the key parameter for the aforementioned effects. Therefore, this paper analyzes the electric field distribution (in the insulation, at the surface, and in the air) for a ±3.5 kV/±400 V, 50 kHz, 25 kW MV/MF transformer employed in a Solid-State Transformer (SST) demonstrator. For reducing the field, a suitable shield is designed. It is found that the shield drastically reduces the field at the surface of the transformer and in the air without increasing the losses.

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“…bushings or machine stators) [28], [31]. Different methods can be used to shape the electric field distribution and can be classified as follows [17], [19], [32].…”

Section: A Shielding Methodsmentioning

confidence: 99%

“…Resistive gradings (particularly with non-linear materials) are difficult to design for a wide frequency range [28], [34].…”

Section: A Shielding Methodsmentioning

confidence: 99%

Section: A Shielding Methodsmentioning

confidence: 99%

Section: Magnetic/electric Field Analysismentioning

confidence: 99%

See 2 more Smart Citations

Electrical shielding of MV/MF transformers subjected to high dv/dt PWM voltages

Guillod

Krismer

Kolar

2017

2017 IEEE Applied Power Electronics Conference and Exposition (APEC)

View full text Add to dashboard Cite

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“…It works efficiently under operations of commercial frequency, therefore erosion of the insulation by partial discharges and heat generation is relieved. [3] However, in recent studies it has become clear that the stress grading system is less effective as PWM voltage waveforms contain high frequency components. Espino-Cortes et al have reported measured results of temperature distribution under repetitive impulse voltage, [4] and Sharifi et al have reported simulated results of voltage distribution under repetitive impulse voltage.…”

Section: Introductionmentioning

confidence: 99%

Potential distribution on stress grading of inverter-fed rotating machines under DC biased voltage

Nakamura

Kumada

Ikeda

et al. 2016

Journal of International Council on Electrical Engineering

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The erosion of the stress grading system of converter-fed rotating machines may occur by partial discharges and heat generation. There remain unclear issues in the formation of the potential and temperature distributions along the stress grading system of coils. In this paper, the potential distributions on the stress grading system of the model coil bar are measured under the application of 1 kHz square wave voltages of 10 kV in peak to peak value with/without 5 kV DC biased voltage. It turns out that DC bias voltage has little effect on potential distribution on a coil surface.

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Automated technique for building high‐frequency equivalent circuits of motors based on electromagnetic field analysis

Maki

2022

Electrical Engineering Japan

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To estimate in advance the high‐frequency impedance of a motor, and its internal voltage distribution when an inverter surge is applied, a technique to derive the circuit constants of various parts of a motor based on electromagnetic field analysis and build its high‐frequency equivalent circuit, where each turn of the coils is separately modeled, has been developed. By switching between 2D and 3D analyses and between 1‐slot and 1‐pole models to accelerate the calculation method and by automating them in parallel, the developed technique even enables non‐experts to build an accurate high‐frequency equivalent circuit of a motor. Based on the accuracy verification, the shared voltage of coils can be estimated with an error of 20% or less by considering the frequency characteristics of the resistance and inductance of each turn of the coils and modeling a lead wire in the measurement setup.

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Impact of inverter drives employing fast-switching devices on form-wound AC machine stator coil stress grading

Cited by 69 publications

References 13 publications

Electrical shielding of MV/MF transformers subjected to high dv/dt PWM voltages

Electrical shielding of MV/MF transformers subjected to high dv/dt PWM voltages

Potential distribution on stress grading of inverter-fed rotating machines under DC biased voltage

Automated technique for building high‐frequency equivalent circuits of motors based on electromagnetic field analysis

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