Reduction of inrush current due to voltage sags by impedance removal timing
First Claim
1. A method for the reduction of inrush current to an electrical load due to voltage sags on an input power AC voltage, comprising the steps of:
- providing a current limiting circuit comprising an selectively removable impedance coupled between the input power AC voltage and the load,providing a sag detector coupled to receive the input power AC voltage, the sag detector operative to provide a signal corresponding to (i) a beginning of a sag, and (ii) an en of a sag in the input power AC voltage during steady state operation of the load;
providing an impedance removal timing circuit coupled to receive the input power AC voltage and a load voltage as measured across the load, the impedance removal timing circuit operative to provide an impedance removal signal in response to detection that the input power AC voltage is less than the load voltage;
applying the input power AC voltage to the load through the current limiting circuit,detecting a sag in the input power AC voltage during steady-state operation of the electrical load;
in response to the signal from the sag detector indicating a beginning of a sag, actuating the current limiting circuit to add the impedance between the input power AC voltage and the load;
detecting the end of a sag with the sag detector;
subsequent to the signal from the sag detector indicating an end of a sag, receiving the impedance removal signal from the impedance removal timing circuit; and
in response to the impedance removal signal, reconnecting the input power AC voltage to the load through the current limiting circuit at any point on the power voltage cycle of the input AC power voltage.
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Accused Products
Abstract
Various systems and methods are provided for minimizing an inrush current to a load after a voltage sag in a power voltage. In one embodiment, a method is provided comprising the steps of applying a power voltage to a load, and detecting a sag in the power voltage during steady-state operation of the load. The method includes the steps of adding an impedance to the load upon detection of the sag in the power voltage, and removing the impedance from the load when the power voltage has reached a predefined point in the power voltage cycle after the power voltage has returned to a nominal voltage.
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Citations
51 Claims
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1. A method for the reduction of inrush current to an electrical load due to voltage sags on an input power AC voltage, comprising the steps of:
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providing a current limiting circuit comprising an selectively removable impedance coupled between the input power AC voltage and the load, providing a sag detector coupled to receive the input power AC voltage, the sag detector operative to provide a signal corresponding to (i) a beginning of a sag, and (ii) an en of a sag in the input power AC voltage during steady state operation of the load; providing an impedance removal timing circuit coupled to receive the input power AC voltage and a load voltage as measured across the load, the impedance removal timing circuit operative to provide an impedance removal signal in response to detection that the input power AC voltage is less than the load voltage; applying the input power AC voltage to the load through the current limiting circuit, detecting a sag in the input power AC voltage during steady-state operation of the electrical load; in response to the signal from the sag detector indicating a beginning of a sag, actuating the current limiting circuit to add the impedance between the input power AC voltage and the load; detecting the end of a sag with the sag detector; subsequent to the signal from the sag detector indicating an end of a sag, receiving the impedance removal signal from the impedance removal timing circuit; and in response to the impedance removal signal, reconnecting the input power AC voltage to the load through the current limiting circuit at any point on the power voltage cycle of the input AC power voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. An apparatus for the reduction of inrush current to an electrical load due to voltage sags on an input power AC voltage, comprising:
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a current limiting circuit including a selectively removable impedance coupled between the input power AC voltage and the electrical load; a sag detector coupled to receive the input power AC voltage, the sag detector operative to provide a signal indicating a (i) a beginning of a sag, and (ii) an end of a sag; an impedance removal timing circuit coupled to receive the input power AC voltage and a load voltage as measured across the load, the impedance removal timing circuit operative to provide an impedance removal signal in response to detection that the input power AC voltage is less than the load voltage; the current limiting circuit being operative, in response to the signal from the sag detector indicating that a sag has begun, to disconnect the input power AC, voltage from the load; and the current limiting circuit being operative, in response to the signal from the sag detector indicating that a sag has ended and to the impedance removal signal, to reconnect the input power AC voltage to the load through the current limiting circuit at a predefined point on a power voltage cycle of the input power AC voltage. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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Specification