Systems and methods for voltage SAG compensation
First Claim
1. A voltage sag compensation device, comprising:
- a first capacitor having a first peak voltage and a second capacitor having a second peak voltage, the second peak voltage being lower than the first peak voltage, the first capacitor and the second capacitor being configured to be charged via an AC rectifier when the voltage sag compensation device is connected to a power line;
a first voltage sag detector configured to detect on the power line a voltage sag of a first predetermined value, and a second voltage sag detector configured to detect on the power line a voltage sag of a second predetermined value, the second predetermined value being greater than the first predetermined value;
an inverter arranged to transform DC power supplied by at least one of the first or second capacitors into AC power; and
control switching, responsive to the first voltage sag detector and to the second voltage sag detector, configured to, upon detection of a voltage sag of the first predetermined value, disconnect the power line from the AC rectifier, disconnect the power line from a load being serviced by the power line, and cause the power line to drive a gating circuit associated with the inverter such that the inverter generates AC voltage that is substantially in phase with AC voltage present on the power line which inverter generated voltage is arranged to be supplied to the load in series with the power line voltage, and further configured to, upon detection of a voltage sag of the second predetermined value, cause the inverter to receive power directly from the first capacitor.
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Accused Products
Abstract
A voltage sag compensation system includes a capacitor charging and discharging module connected to an AC rectifier and to an inverter, a two stage voltage detector configured to detect a degree of voltage sag that is present on a power line, and an inverter gating module selectively connectable to the power line in response to the two stage voltage detector and configured to provide gating signals to the inverter. The system further includes a low DC bus switch out module configured to monitor an output voltage of the capacitor charging and discharging module and to disable the inverter gating module from providing the gating signals to the inverter when voltage associated with the capacitor charging and discharging module falls below a predetermined value.
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Citations
25 Claims
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1. A voltage sag compensation device, comprising:
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a first capacitor having a first peak voltage and a second capacitor having a second peak voltage, the second peak voltage being lower than the first peak voltage, the first capacitor and the second capacitor being configured to be charged via an AC rectifier when the voltage sag compensation device is connected to a power line; a first voltage sag detector configured to detect on the power line a voltage sag of a first predetermined value, and a second voltage sag detector configured to detect on the power line a voltage sag of a second predetermined value, the second predetermined value being greater than the first predetermined value; an inverter arranged to transform DC power supplied by at least one of the first or second capacitors into AC power; and control switching, responsive to the first voltage sag detector and to the second voltage sag detector, configured to, upon detection of a voltage sag of the first predetermined value, disconnect the power line from the AC rectifier, disconnect the power line from a load being serviced by the power line, and cause the power line to drive a gating circuit associated with the inverter such that the inverter generates AC voltage that is substantially in phase with AC voltage present on the power line which inverter generated voltage is arranged to be supplied to the load in series with the power line voltage, and further configured to, upon detection of a voltage sag of the second predetermined value, cause the inverter to receive power directly from the first capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A voltage sag compensation system, comprising:
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a capacitor charging and discharging module connected to an AC rectifier and to an inverter; a two stage voltage detector configured to detect a degree of voltage sag that is present on a power line; an inverter gating module selectively connectable to the power line in response to the two stage voltage detector and configured to provide gating signals to the inverter; and a low DC bus switch out module configured to monitor an output voltage of the capacitor charging and discharging module and to disable the inverter gating module from providing the gating signals to the inverter when voltage associated with the capacitor charging and discharging module falls below a predetermined value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of compensating for voltage sag on a power line comprising:
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charging a first capacitor and a second capacitor using an AC rectifier connected to a power line; detecting, on the power line, a voltage sag of a predetermined amount; disconnecting the power line from the AC rectifier and connecting the power line in such a way as to drive a gating circuit for a DC-AC inverter; inverting DC voltage supplied by at least one of the first capacitor or the second capacitor and applying resulting AC voltage to the power line in series therewith; and monitoring a voltage level of the DC voltage and disconnecting the power line from driving the gating circuit when the DC voltage falls below a predetermined value. - View Dependent Claims (22, 23, 24, 25)
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Specification