Implementation of a Sensorless Control System with a Flying-Start Feature for an Asynchronous Machine as a Ship Shaft Generator.

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Title: Implementation of a Sensorless Control System with a Flying-Start Feature for an Asynchronous Machine as a Ship Shaft Generator.
Authors: Kozak, Maciej1 (AUTHOR) m.kozak@pm.szczecin.pl, Olszański, Kacper1 (AUTHOR), Kozak, Marcin1 (AUTHOR)
Source: Energies (19961073). Feb2026, Vol. 19 Issue 3, p776. 19p.
Subject Terms: *Sensorless control systems, *Induction generators, *Speed measurements, *Marine engineering, *Squirrel cage motors, *Voltage
Abstract: Squirrel-cage induction generators often perform better without a mechanical speed sensor. Eliminating an encoder or resolver removes one of the most fragile and failure-prone components, while modern control algorithms can estimate speed with sufficient accuracy. Shaft-mounted sensors are vulnerable to heat, vibration, dust, moisture, and electrical noise; they require precise mounting and additional cabling and typically fail long before the machine itself. In many industrial and marine applications, unplanned shutdowns are more often caused by damaged sensors or cables than by the generator. Unlike sensorless speed-detection methods developed for motoring operation, the proposed approach targets the generator mode, where both phase currents and the DC-link voltage are measured. It uses two indicators: the magnitude and sign of the active current, and the instantaneous rise in DC-link voltage when the converter output frequency matches the machine's shaft speed. Because active current remains negative over a wide frequency range during start-up, its sign change alone cannot uniquely identify the synchronization point. In generator operation, however, the DC-link capacitor voltage provides an additional criterion: the speed at which power reverses sign, indicated by a change in the sign of the DC-voltage derivative. As the inverter frequency approaches the machine rotational frequency from below, the DC voltage increases, reaches a maximum at maximum slip, and then decreases once the inverter frequency exceeds the machine speed. The article demonstrates how these signals can be used in practice to identify the rotational speed of a squirrel-cage generator. [ABSTRACT FROM AUTHOR]
Database: Energy & Power Source
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Header DbId: enr
DbLabel: Energy & Power Source
An: 191587255
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  Label: Title
  Group: Ti
  Data: Implementation of a Sensorless Control System with a Flying-Start Feature for an Asynchronous Machine as a Ship Shaft Generator.
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  Label: Authors
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  Data: <searchLink fieldCode="AR" term="%22Kozak%2C+Maciej%22">Kozak, Maciej</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> m.kozak@pm.szczecin.pl</i><br /><searchLink fieldCode="AR" term="%22Olszański%2C+Kacper%22">Olszański, Kacper</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kozak%2C+Marcin%22">Kozak, Marcin</searchLink><relatesTo>1</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Energies+%2819961073%29%22">Energies (19961073)</searchLink>. Feb2026, Vol. 19 Issue 3, p776. 19p.
– Name: Subject
  Label: Subject Terms
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  Data: *<searchLink fieldCode="DE" term="%22Sensorless+control+systems%22">Sensorless control systems</searchLink><br />*<searchLink fieldCode="DE" term="%22Induction+generators%22">Induction generators</searchLink><br />*<searchLink fieldCode="DE" term="%22Speed+measurements%22">Speed measurements</searchLink><br />*<searchLink fieldCode="DE" term="%22Marine+engineering%22">Marine engineering</searchLink><br />*<searchLink fieldCode="DE" term="%22Squirrel+cage+motors%22">Squirrel cage motors</searchLink><br />*<searchLink fieldCode="DE" term="%22Voltage%22">Voltage</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Squirrel-cage induction generators often perform better without a mechanical speed sensor. Eliminating an encoder or resolver removes one of the most fragile and failure-prone components, while modern control algorithms can estimate speed with sufficient accuracy. Shaft-mounted sensors are vulnerable to heat, vibration, dust, moisture, and electrical noise; they require precise mounting and additional cabling and typically fail long before the machine itself. In many industrial and marine applications, unplanned shutdowns are more often caused by damaged sensors or cables than by the generator. Unlike sensorless speed-detection methods developed for motoring operation, the proposed approach targets the generator mode, where both phase currents and the DC-link voltage are measured. It uses two indicators: the magnitude and sign of the active current, and the instantaneous rise in DC-link voltage when the converter output frequency matches the machine's shaft speed. Because active current remains negative over a wide frequency range during start-up, its sign change alone cannot uniquely identify the synchronization point. In generator operation, however, the DC-link capacitor voltage provides an additional criterion: the speed at which power reverses sign, indicated by a change in the sign of the DC-voltage derivative. As the inverter frequency approaches the machine rotational frequency from below, the DC voltage increases, reaches a maximum at maximum slip, and then decreases once the inverter frequency exceeds the machine speed. The article demonstrates how these signals can be used in practice to identify the rotational speed of a squirrel-cage generator. [ABSTRACT FROM AUTHOR]
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RecordInfo BibRecord:
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    Identifiers:
      – Type: doi
        Value: 10.3390/en19030776
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 19
        StartPage: 776
    Subjects:
      – SubjectFull: Sensorless control systems
        Type: general
      – SubjectFull: Induction generators
        Type: general
      – SubjectFull: Speed measurements
        Type: general
      – SubjectFull: Marine engineering
        Type: general
      – SubjectFull: Squirrel cage motors
        Type: general
      – SubjectFull: Voltage
        Type: general
    Titles:
      – TitleFull: Implementation of a Sensorless Control System with a Flying-Start Feature for an Asynchronous Machine as a Ship Shaft Generator.
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            NameFull: Kozak, Maciej
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            NameFull: Olszański, Kacper
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            NameFull: Kozak, Marcin
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          Dates:
            – D: 01
              M: 02
              Text: Feb2026
              Type: published
              Y: 2026
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              Value: 19961073
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              Value: 19
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            – TitleFull: Energies (19961073)
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