System and method for uninterruptible power supply intelligent transfer
First Claim
1. A method for detecting and compensating for an under voltage fault condition which arises when a low impedance fault occurs on a bypass line of an uninterruptible power supply (UPS) as a result of a disruption of an AC output mains (Vout) signal present on the bypass line, which reduces the Vout signal below a nominal AC mains voltage output (Voutnominal), and wherein a component is disposed downstream of the UPS and receives power from the UPS as a changeover is made from a high efficiency mode of operation to a voltage/frequency independent (VFI) mode in which the UPS is supplying power to a load, and the component is upstream of the load but downstream of the UPS, the method comprising:
- performing successive voltage measurements at a plurality of points during a first half cycle of the Vout signal to integrate the Vout signal until a zero crossing of the Vout signal is detected;
using the successive voltage measurements to detect the disruption of the Vout signal and a percentage representing a missing voltage from the Vout signal during the disruption;
using the UPS to supply a compensation voltage (Vcomp) which is added to the Vout signal to restore the Vout signal to a level at least approximately equal to Voutnominal; and
further comprising determining when Vout cannot be restored to Voutnominal by adding a predetermined maximum level for Vcomp before a next zero crossing point will occur, and adding a first portion of Vcomp before said next zero crossing occurs, and a second portion of Vcomp after said next zero crossing has passed.
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Accused Products
Abstract
A method is disclosed which makes use of an intelligent transfer algorithm for a UPS when the UPS is required to switch from a high efficiency mode of operation (VFD or VI) to an independent mode of operation (VFI), as a result of an under voltage condition occurring on the bypass line of the UPS. The method involves performing successive voltage measurements at a plurality of points during a first half cycle of an AC mains (Vout) signal to integrate the Vout signal until a zero crossing of the Vout signal is detected. Successive voltage measurements are used to detect the disruption of the Vout signal and a percentage of missing voltage area from the Vout signal during the disruption. The UPS then supplies a compensation voltage (Vcomp) which is added to the Vout signal to restore the Vout signal to a level at least approximately equal to a nominal AC mains voltage output signal (Voutnominal).
21 Citations
17 Claims
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1. A method for detecting and compensating for an under voltage fault condition which arises when a low impedance fault occurs on a bypass line of an uninterruptible power supply (UPS) as a result of a disruption of an AC output mains (Vout) signal present on the bypass line, which reduces the Vout signal below a nominal AC mains voltage output (Voutnominal), and wherein a component is disposed downstream of the UPS and receives power from the UPS as a changeover is made from a high efficiency mode of operation to a voltage/frequency independent (VFI) mode in which the UPS is supplying power to a load, and the component is upstream of the load but downstream of the UPS, the method comprising:
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performing successive voltage measurements at a plurality of points during a first half cycle of the Vout signal to integrate the Vout signal until a zero crossing of the Vout signal is detected; using the successive voltage measurements to detect the disruption of the Vout signal and a percentage representing a missing voltage from the Vout signal during the disruption; using the UPS to supply a compensation voltage (Vcomp) which is added to the Vout signal to restore the Vout signal to a level at least approximately equal to Voutnominal; and further comprising determining when Vout cannot be restored to Voutnominal by adding a predetermined maximum level for Vcomp before a next zero crossing point will occur, and adding a first portion of Vcomp before said next zero crossing occurs, and a second portion of Vcomp after said next zero crossing has passed. - View Dependent Claims (2, 3, 4, 5)
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6. A method for detecting and compensating for an under voltage fault condition which arises when a low impedance fault occurs on a bypass line of an uninterruptible power supply (UPS) as a result of a disruption of an AC output mains (Vout) signal present on the bypass line, which reduces the Vout signal below a nominal AC mains voltage output (Voutnominal), and wherein a component is disposed downstream of the UPS and receives power from the UPS as a changeover is made from a high efficiency mode of operation to a voltage/frequency independent (VFI) mode in which the UPS is supplying power to a load, and the component is upstream of the load but downstream of the UPS, the method comprising:
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setting a predetermined percentage voltage compensation threshold relating to a percentage of voltage that is lost during the disruption of the Vout signal, and below which no action will be taken to compensate for the disruption; performing successive voltage measurements at a plurality of points during a first half cycle of the Vout signal to integrate the Vout signal until a zero crossing of the Vout signal is detected; using the successive voltage measurements to detect the disruption of the Vout signal and a percentage representing the missing voltage from the Vout signal during the disruption; determining if the percentage of missing voltage from the Vout signal during the disruption has resulted in a percentage of voltage lost from the Vout signal that exceeds the predetermined percentage voltage compensation threshold, and then; using the UPS to supply a compensation voltage (Vcomp) which is added to the Vout signal to the Vout signal to a level at least approximately equal to Voutnominal; and further comprising determining when Vout cannot be restored to Voutnominal by adding a predetermined maximum level for Vcomp before a next zero crossing point will occur, and adding a first portion of Vcomp before said next zero crossing occurs, and a second portion of Vcomp after said next zero crossing has passed. - View Dependent Claims (7, 8, 9, 10)
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11. A system having an intelligent transfer algorithm to detect and compensate for an under voltage fault condition which arises when a low impedance fault occurs on a bypass line of an uninterruptible power supply (UPS) as a result of a disruption of an AC output mains (Vout) signal present on the bypass line, which reduces the Vout signal below a nominal AC mains voltage output (Voutnominal), and wherein a component is disposed downstream of the UPS and receives power from the UPS as a changeover is made from a high efficiency mode of operation to a voltage/frequency independent (VFI) mode in which the UPS is supplying power to a load, and the component is upstream of the load but downstream of the UPS, the system comprising:
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a UPS on which the intelligent transfer algorithm is running, the UPS configured to; perform successive voltage measurements at a plurality of points during a first half cycle of the Vout signal to integrate the Vout signal until a zero crossing of the Vout signal is detected; use the successive voltage measurements to detect the disruption of the Vout signal and a percentage representing a missing voltage area from the Vout signal during the disruption; use the UPS to supply a compensation voltage (Vcomp) which is added to the Vout signal to restore the Vout signal to a level at least approximately equal to Voutnominal; and wherein the UPS is further configured to determine when Vout cannot be restored to Voutnominal by adding a full amount of Vcomp before a next zero crossing point will occur, and operates to add a first portion of Vcomp before said next zero crossing occurs, and a second portion of Vcomp after said next zero crossing has passed. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification