Active current surge limiters with inrush current anticipation
First Claim
1. A method for reducing inrush current to an electrical load in response to anticipation of the inrush current due to detection of a disturbance occurring within a quarter to one half cycle in an input AC power supply coupled to the electrical load, comprising the steps of:
- at the initial application of power from the input AC power supply at start-up, limiting the current to the electrical load by connecting a current limiting impedance between the input AC power supply and the electrical load;
coupling the input AC power supply to the electrical load after startup by removing the current limiting impedance;
monitoring the voltage of the input AC power supply at a node between the current limiting impedance and the electrical load to detect a disturbance in the input AC power supply occurring within a quarter cycle to one half cycle of the AC power;
detecting a disturbance in the input AC power supply that would cause an inrush current to the electrical load after the disturbance has ended;
in response to detection of the beginning of a disturbance in the input AC power supply, connecting the current limiting impedance between the input AC power supply and the electrical load;
repeatedly monitoring the voltage of the input AC power supply at a node prior to the current limiting impedance to detect the end of the disturbance in the input AC power supply, while maintaining the current limiting impedance; and
in response to detection that the disturbance in the input AC power supply has ended by return of the voltage to a normal level, coupling the input AC power supply to the electrical load by removing the current limiting impedance,whereby inrush current to the load is impeded at start-up and in response to detection of a disturbance in the input AC power supply.
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Abstract
Active current surge limiters and methods of use are disclosed. One exemplary system, among others, comprises a current limiter, including an interface configured to be connected between a power supply and a load; a disturbance sensor, configured to monitor the power supply for a disturbance during operation of the load; and an activator, configured to receive a control signal from the disturbance sensor and to activate the current limiter based on the control signal.
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Citations
38 Claims
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1. A method for reducing inrush current to an electrical load in response to anticipation of the inrush current due to detection of a disturbance occurring within a quarter to one half cycle in an input AC power supply coupled to the electrical load, comprising the steps of:
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at the initial application of power from the input AC power supply at start-up, limiting the current to the electrical load by connecting a current limiting impedance between the input AC power supply and the electrical load; coupling the input AC power supply to the electrical load after startup by removing the current limiting impedance; monitoring the voltage of the input AC power supply at a node between the current limiting impedance and the electrical load to detect a disturbance in the input AC power supply occurring within a quarter cycle to one half cycle of the AC power; detecting a disturbance in the input AC power supply that would cause an inrush current to the electrical load after the disturbance has ended; in response to detection of the beginning of a disturbance in the input AC power supply, connecting the current limiting impedance between the input AC power supply and the electrical load; repeatedly monitoring the voltage of the input AC power supply at a node prior to the current limiting impedance to detect the end of the disturbance in the input AC power supply, while maintaining the current limiting impedance; and in response to detection that the disturbance in the input AC power supply has ended by return of the voltage to a normal level, coupling the input AC power supply to the electrical load by removing the current limiting impedance, whereby inrush current to the load is impeded at start-up and in response to detection of a disturbance in the input AC power supply. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus for reducing inrush current to an electrical load in response to anticipation of the inrush current due to detection of a disturbance on an input AC power supply, comprising:
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a selectively actuatable current-limiting impedance coupled between an input AC power supply and the electrical load, the current-limiting impedance comprising (a) an impedance, and (b) a relay in parallel with the impedance and having contacts that are in an open position to couple the input AC power supply to the electrical load through the impedance and close in response to a control signal to couple the input AC power supply to the electrical load and bypass the impedance; and a control circuit that provides the control signal to open and close the relay, the control circuit operative to continuously monitor the voltage of the input AC power supply at a node between the current-limiting impedance and the electrical load occurring within a quarter cycle to one half cycle of the AC power so as to detect a disturbance; the control circuit operative at the initial application of power from the input AC power supply at start-up to limit the current to the electrical load by connecting the current-limiting impedance between the input AC power supply and the electrical load; the control circuit operative to couple the input AC power supply to the electrical load after startup by removing the current-limiting impedance; the control circuit operative in response to detection of a disturbance in the input AC power supply to connect the current-limiting impedance between the input AC power supply and the electrical load; the control circuit further operative to monitor the voltage of the input AC power supply at a node prior to the current limiting impedance to detect the end of the disturbance in the input AC power supply, while maintaining the current-limiting impedance; and the control circuit further operative in response to detection that the disturbance in the input AC power supply has ended by return of the input voltage to a normal level, to couple the input AC power supply to the electrical load by removing the current-limiting impedance, whereby inrush current to the load is impeded at start-up and in response to detection of a disturbance in the input AC power supply. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification