US 6,782,989 B2 · Process for switching between mains supply and a frequency inverter and vice versa

Abstract

Process and device for controlling the drive of a conveyor system (10), specifically in the form of an escalator or passenger conveyor, which can be switched from load to no-load operation, comprising a drive motor (26) and a variable frequency converter (42), which is at least controllable with respect to the frequency of its output voltage, wherein, under load, the drive motor (26) is supplied with a line voltage with an essentially constant line frequency and, at no-load, is supplied the output voltage of the variable frequency converter's (42), wherein, prior to a changeover from no-load to load operation, the output frequency of the variable frequency converter (42) is essentially brought with phase accuracy to the line frequency by means of a PLL device (30), and wherein this changeover is brought about as soon as this phase conformance has been realized.

Claims25

Dependent claims

Process for controlling a drive means of a conveyor system (10), specifically, in a form of an escalator or a passenger conveyor, which can be switched between a load and a no-load operation, the drive means including a drive motor (26) and a variable frequency converter (42), wherein the frequency converter is at least controllable in terms of an output frequency of an output voltage, the process comprising the steps of:

supplying, the drive motor (26) with a line voltage with an essentially constant line frequency in the load operation;
supplying the drive motor (26), with the output voltage of the variable frequency converter (42) in the no-load operation;
wherein prior to a changeover from the no-load to the load operation or vice versa, essentially bringing the output frequency of the variable frequency converter (42) to the line frequency and determining that a phase of the line voltage is essentially in conformance with a phase of the output voltage of the variable frequency converter by means of a PLL device (30).

Electric control device for controlling a drive means of a conveyor system (10), specifically in a form of an escalator or passenger conveyor, the conveyor system comprising a line voltage input with an essentially constant line frequency and a drive motor (26), the control device comprising:

a variable frequency converter (42), which at least is controllable in terms of a frequency of its output voltage;
a controllable changeover system for switching between a load operation and a no-load operation wherein during the load operation, the drive motor (26) is supplied with the line voltage, and in the no-load operation is supplied with the output voltage of the variable frequency converter (42);
and
a PLL device (30) wherein, prior to a changeover from the no-load to the load operation or vice versa, the output frequency of the variable frequency converter (42) is, essentially regulated to the frequency and phase of the line voltage.

1 more element

Dependencies are inferred from the claim text.

Process for switching between mains supply and a frequency inverter and vice versa

Life of this patent

Process for switching between mains supply and a frequency inverter and vice versa

Life of this patent

Abstract

Claims25