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. |
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| 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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