FAIL-SAFE SPEED MONITORING OF A DRIVE

The invention relates to fail-safe monitoring of the speed of a drive, which has at least a converter, a motor, and a rotational speed sensor, wherein a target rotational speed is specified to the drive and an actual rotational speed is sensed by means of the speed sensor. In order to achieve a high...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: MEINARDUS MARTIN, RASENACK WOLF-MARTIN, CZERNY WERNER, VLAIC IULIU
Format: Patent
Sprache:chi ; eng
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Beschreibung
Zusammenfassung:The invention relates to fail-safe monitoring of the speed of a drive, which has at least a converter, a motor, and a rotational speed sensor, wherein a target rotational speed is specified to the drive and an actual rotational speed is sensed by means of the speed sensor. In order to achieve a high safety integrity level while avoiding the disadvantages of the known solutions, according to the invention, a substitute rotational speed is calculated and three plausibility checks are performed in a safety program of a safety CPU, wherein in each case two of the following three values are checked: target rotational speed, actual rotational speed, and substitute rotational speed. Because the calculated substitute rotational speed is independent of the sensor, even sensor errors that are difficult or impossible to detect by means of prior hardware solutions can be detected. The substitute rotational speed can be determined, for example, from the initial frequency of a converter or from thequotient of EMF and magne