Common-mode voltage limits for the transformerless design of MV drives to prevent bearing current issues

Mechlinski, Marius; Schröder, S.; Shen, Jie; Doncker, Rik W. De

doi:10.1109/ecce.2016.7854928

Cited by 7 publications

(9 citation statements)

References 12 publications

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“…Thus, for minimal alteration of φ HB , and consequently minimal additional SMC AC voltage amplitude required to synthesize required branchlevel voltage (refer to V p of Fig. 5), the maximal value of vHBAC /V HBDC = 1 − k res = 1 should be selected ( 17), (19), which proves the validity of choices ( 18)- (19). For the purpose of control voltage reserve, this ratio should be kept below unity, as aforementioned.…”

Section: Smc Insertion Voltage Determinationmentioning

confidence: 82%

“…Since there are four equations and six variables, two among them are to be chosen freely. The selection is made to set V HBDC (18) and vHBAC (19) voltage amplitudes in a way to maximally utilize insertion voltage potential of installed HB SMs, respecting (electrical) SM voltage constraints ( 12)- (13). This leads to the design with the minimal number of lossier and more expensive FB SMs, in favor of more efficient and cheaper HB units.…”

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

“…This leads to the design with the minimal number of lossier and more expensive FB SMs, in favor of more efficient and cheaper HB units. As certain control voltage reserve must be accounted for, AC voltage component of HB SMC should not exceed (19), where k res determines AC voltage control reserve. Factor k res is defined as a fraction of maximal available AC voltage, and is taken as 5 % in this work, i.e.…”

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

“…Finally, four equations with four variables are left, and the system can be solved. HB displacement angle is calculated from ( 17) and (19).…”

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

“…One possible solution to the problem relies on Common Mode (CM)-voltage injection [16], [17]. While such Variable Speed Drives (VSDs) are in use [18], the additional CM voltage-imposed stress, ranging up to rated winding voltage, may prove prohibitively high when retrofitting PHSPs machines originally designed for sine-wave grid supply [19], [20]. Reduction of average SM voltage at lower-than-rated frequency, thus allowing for higher capacitor voltage ripple, has been proposed in [21], enabling CM-voltage-free operation down to 30 % of rated frequency.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Modular Multilevel Converter Design and Control for Variable Speed Pumped Hydro Storage Plants

Basic¹,

Utvić

Dujić

2021

IEEE Access

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Hybrid modular multilevel converter control and design for pumped hydro storage plants is presented, addressing application-specific shortcoming of conventional back-to-back half-bridge modular multilevel converter: high common-mode-voltage machine stress. Common-mode-voltage-free operation in the entire or partial frequency range is enabled by variable DC link voltage control, through introduction of minimal full-bridge submodule share in hybrid active front-end converter stage. The developed generalized converter design approach for arbitrary DC link voltage range operation and additional internal energy balancing control layers enable down-to-zero DC voltage control. The results are verified through highfidelity switched-model simulations of 6 kV converter, with 10/6 ratio of full-bridge to half-bridge submodules in active front-end. The analyzed hybrid active front-end stage benefits from lower converter losses for equal machine operation flexibility compared to full-bridge design, while trade-off between gridside power factor range and full-bridge submodule share is offered within the design stage. Compared to the state-of-the-art, zero-to-rated DC link voltage operation is possible at lower full-bridge submodule share (62 % against 75 %), at the penalty of reduced grid-side power factor. Alternatively, operation at higher fullbridge submodule share (62 % against 50 % existing solution) enables grid-side reactive power support over wide speed range, without branch current overload.INDEX TERMS Hydroelectric power generation, modular multilevel converter, retrofit.

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Section: Smc Insertion Voltage Determinationmentioning

confidence: 82%

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

“…Finally, four equations with four variables are left, and the system can be solved. HB displacement angle is calculated from ( 17) and (19).…”

Section: Smc Insertion Voltage Determinationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hybrid Modular Multilevel Converter Design and Control for Variable Speed Pumped Hydro Storage Plants

Basic¹,

Utvić

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IEEE Access

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A Review of Modeling and Mitigation Techniques for Bearing Currents in Electrical Machines With Variable-Frequency Drives

et al. 2022

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The converter switching in variable-frequency drives can generate high frequency common mode voltage between the machine winding and the converter ground, leading to high frequency parasitic currents which can flow through the machine bearings unless precautions are taken in design and installation. These parasitic and unintended currents in the bearings cause deterioration of the lubrication film and surface damage to the rolling elements of the bearings. These problems will be exacerbated as wide-bandgap semiconductors with faster switching rise times start becoming more widespread in variable-frequency drives. This paper reviews the modelling and mitigation techniques of high frequency bearing currents in inverter fed AC drives. It aims to provide a solid base for the research community to further understanding the bearing currents phenomenon and helping to find novel improved technique for their mitigation and measurement.

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System-Level Conducted EMI Model for SiC Powertrain of Electric Vehicles

Jia

Dong

et al. 2020

2020 IEEE Applied Power Electronics Conference and Exposition (APEC)

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Common-mode voltage limits for the transformerless design of MV drives to prevent bearing current issues

Cited by 7 publications

References 12 publications

Hybrid Modular Multilevel Converter Design and Control for Variable Speed Pumped Hydro Storage Plants

Hybrid Modular Multilevel Converter Design and Control for Variable Speed Pumped Hydro Storage Plants

A Review of Modeling and Mitigation Techniques for Bearing Currents in Electrical Machines With Variable-Frequency Drives

System-Level Conducted EMI Model for SiC Powertrain of Electric Vehicles

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