US 6,634,463 B2Granted

Switch over from the mains supply to a frequency converter by a phase correction process for an escalator drive

AssigneeOtiscelecator Company

InventorsStefan Spannhake, Michael Mann, Gunter Blechschmidt, Peter Walden, Robert Oesterle, Michael B. Kocur

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Abstract

Method for controlling the drive of a conveyor device (10), especially in the form of an escalator or moving sidewalk, switchable between load operation and no-load operation, having a drive motor (26) and a frequency changer (42) controllable at least with respect to frequency and phase position of its output voltage, in which the drive motor (26) in load operation is fed with a line voltage with essentially constant line frequency and in no-load operation with the frequency changer output voltage, the phase difference between the phase position of the line voltage and the phase position of the frequency changer output voltage is determined, the phase position of the frequency changer output voltage is corrected according to the determined phase difference and therefore essentially brought into agreement with the phase position of the line voltage and switching is produced as soon as this agreement is reached.

Claims19

Dependent claims

Method for controlling the drive of a conveyor device (10), especially in the form of an escalator or moving sidewalk, switching between load operation and no-load operation, having a drive motor (26) and a frequency changer (42) controllable at least with respect to frequency and phase position of its output voltage, in which:

the drive motor (26) in load operation is fed with a line voltage with essentially constant line frequency and in no-load operation with the frequency changer output voltage;
the phase difference between the phase position of the line voltage and the phase position of the frequency changer output voltage is determined;
the phase position of the frequency changer output voltage is corrected according to the determined phase difference and therefore brought essentially into agreement with the phase position of the line voltage;
switching is produced as soon as this agreement is reached;
and wherein to determine the phase difference the time occurrence of comparable events on the voltage trend of the line voltage and frequency changer output voltage are recorded and the phase difference between the phase positions of the line frequency and the frequency changer output voltage is derived from the time difference of occurrence of these events.

2 more elements

Electrical control device to control the drive of a conveyor device (10), especially in the form of an escalator or a moving sidewalk, switchable between load operation and no-load operation, having a line voltage connection to supply a line voltage with essentially constant line frequency and a drive motor (26), having:

a frequency changer (42) controllable at least with respect to the frequency and phase position of its output voltage;
a controllable switching device (K1, K2) with a load operation switching state in which the drive motor (26) is connected to the line voltage connection and a no-load operation switching state in which the drive motor (26) is connected to the frequency changer (42), so that the drive motor (26) in load operation is fed with a line voltage with essentially constant line frequency and in no-load operation with the output voltage of the frequency changer (42);
a phase difference determination device (30), comprising a Schmitt trigger device by means of which, before switching from load operation to no-load operation, the difference between the phase position of the line voltage and the phase position of the output voltage of the frequency changer (42) can be determined;
and a phase control device (48, 50), by means of which the phase position of the output voltage of the frequency changer (42) can be controlled as a function of the determined phase difference essentially in agreement with the phase position of the line voltage;
in which switching of the switching device (K1, K2) is controllable as a function of achievement of such phase agreement.

2 more elements

Dependencies are inferred from the claim text.