IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0230319
(2011-09-12)
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등록번호 |
US-8488285
(2013-07-16)
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발명자
/ 주소 |
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출원인 / 주소 |
- Georgia Tech Research Corporation
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대리인 / 주소 |
Morris, Manning & Martin, LLP
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인용정보 |
피인용 횟수 :
1 인용 특허 :
60 |
초록
▼
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
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.
대표청구항
▼
1. An active current surge limiting apparatus for reduction of inrush current to an electrical load in response to detection of a disturbance in an input AC power supply coupled to the electrical load, comprising: a current-limiting circuit coupled between the input power supply and the electrical l
1. An active current surge limiting apparatus for reduction of inrush current to an electrical load in response to detection of a disturbance in an input AC power supply coupled to the electrical load, comprising: a current-limiting circuit coupled between the input power supply and the electrical load, the current-limiting circuit comprising a parallel arrangement of (a) current limiter and (b) a relay having contacts that are in a normally-open position at start-up and a closed position in response to a relay control signal that couples the input power supply to the electrical load and bypasses the current limiter;an AC voltage peak detector circuit for providing a control signal when the value of the input AC power exceeds a predetermined voltage level; anda retriggerable pulse circuit responsive to the control signal from the AC voltage peak detector circuit for providing the relay control signal having a predetermined nominal duration, such that the relay is maintained in the closed position so long as the input AC power exceeds the predetermined voltage level on each cycle of a predetermined number of AC cycles,whereby the current limiter provides an impedance for reduction of inrush current to the electrical load upon startup and upon opening of the relay in response to expiration of the relay control signal and is bypassed upon closing of the relay. 2. The apparatus of claim 1, wherein the current limiter comprises a negative temperature coefficient (NTC) component. 3. The apparatus of claim 1, further discloses wherein the AC voltage peak detector comprises an isolator. 4. The apparatus of claim 3, wherein the isolator comprises an optocoupler. 5. The apparatus of claim 1, wherein the peak detector circuit comprises a resistor-capacitor (RC) circuit that charges when the input AC power exceeds the predetermined voltage level and discharges when the input AC power is less than the predetermined voltage level, and wherein the control signal is a pulse that begins when the capacitor is charged to a first predetermined level and ends when the capacitor discharges to a second predetermined level. 6. The apparatus of claim 5, wherein the predetermined voltage level of the input AC power is selected to a value that maintains the charge on the capacitor of the RC circuit for a duration that exceeds the duration of the relay control signal. 7. The apparatus of claim 5, wherein the values of the RC circuit are selected to provide a time constant that is similar to the time constant of the RC characteristics of the electrical load. 8. The apparatus of claim 1, wherein the control signal comprises a pulse having a duration that begins when the input AC power voltage exceeds the predetermined voltage level and ends when the AC power voltage is less than the predetermined voltage level. 9. The apparatus of claim 1, wherein the AC voltage peak detector circuit comprises: a diode bridge for rectifying the input AC power and providing a rectified power signal; anda resistor-capacitor (RC) circuit operative to charge when the rectified power signal exceeds the predetermined voltage level and discharge when the rectified power signal is less than the predetermined voltage level, thereby providing a charging current pulse; andan optoisolator for isolating the charging current pulse and providing the control signal. 10. The apparatus of claim 9, further comprising a line impedance simulator circuit coupled to the diode bridge, whereby the line impedance simulator circuit and the RC circuit simulate the electrical characteristics of the electrical load. 11. The apparatus of claim 9, wherein the control signal is a pulse that begins when the capacitor is charged to a first predetermined level and ends when the capacitor discharges to a second predetermined level. 12. The apparatus of claim 1, further comprising line impedance simulator circuit coupled to the AC voltage peak detector circuit. 13. The apparatus of claim 1, wherein the retriggerable pulse circuit comprises a retriggerable monostable multivibrator. 14. The apparatus of claim 1, wherein the relay control signal comprises a pulse of nominal duration of about 8.33 mS, and wherein the relay control signal is maintained at a value that keeps the relay in the closed position so long as the AC voltage peak detector circuit provides the control signal. 15. The apparatus of claim 1, further comprising a semiconductor switch that is turned on by the relay control signal so as to maintain the relay in the closed position so long as the relay control signal is maintained. 16. The apparatus of claim 1, wherein the retriggerable pulse circuit controls activation of the coil of the relay by maintaining the contacts in the closed position during provision of the control signal from the AC voltage peak detector, and wherein the control signal from the AC voltage peak detector comprises signal pulses that correspond to the cycles of AC power from the input power supply, the signal pulses operative to retrigger the retriggerable pulse circuit during normal conditions on the input power supply and maintain the relay contacts closed,whereby the relay contacts open if the signal pulses are not provided to retrigger the retriggerable pulse circuit. 17. The apparatus of claim 1, wherein the apparatus is coupled to a reactive load, and wherein the circuit maintains the relay in an open position during an initial startup condition of power being provided from the input power supply, and further comprising a timer circuit operative to place the relay in the closed position after expiration of a predetermined time period after the startup condition. 18. The apparatus of claim 17, wherein the timer circuit comprises an inductor and resistor for simulating the startup characteristics of the electrical load and an resistor-capacitor (RC) circuit. 19. The apparatus of claim 1, wherein the disturbance is a voltage sag that results in the AC voltage peak detector not providing the control signal due to the input AC power not reaching the predetermined voltage level for a period of time. 20. The apparatus of claim 1, wherein the disturbance comprises sufficient variations in the voltage or current of the input AC power supply. 21. A method for reducing inrush current to an electrical load in response to detection of a disturbance in an input AC power supply coupled to the electrical load, comprising the steps of: providing a current-limiting circuit coupled between the input power supply and the electrical load, the current-limiting circuit comprising a parallel arrangement of (a) current limiter and (b) a relay having contacts that are in a normally-open position at start-up and a closed position in response to a relay control signal that couples the input power supply to the electrical load and bypasses the current limiter;providing a control signal when the value of the input AC power exceeds a predetermined voltage level; andrepeatedly generating the relay control signal with a predetermined nominal duration in response to each occurrence of the control signal such that the relay is maintained in the closed position so long as the input AC power exceeds the predetermined voltage level,whereby the current limiter provides an impedance for reduction of inrush current to the electrical load upon startup and upon opening of the relay in response to expiration of the relay control signal and is bypassed upon closing of the relay. 22. The method of claim 21, wherein the current limiter comprises a negative temperature coefficient (NTC) component. 23. The method of claim 21, wherein the relay control signal is provided by a retriggerable pulse circuit. 24. The method of claim 23, wherein the retriggerable pulse circuit comprises a retriggerable monostable multivibrator. 25. The method of claim 23, further comprising the step of isolating the control signal from the retriggerable pulse circuit with an optoisolator. 26. The method of claim 21, wherein the control signal is provided from a peak detector circuit comprising a resistor-capacitor (RC) circuit that charges when the input AC power exceeds the predetermined voltage level and discharges when the input AC power is less than the predetermined voltage level, and wherein the control signal is a pulse that begins when the capacitor is charged to a first predetermined level and ends when the capacitor discharges to a second predetermined level. 27. The method of claim 26, wherein the predetermined voltage level of the input AC power is selected to a value that maintains the charge on the capacitor of the RC circuit for a duration that exceeds the duration of the relay control signal. 28. The method of claim 26, wherein the values of the RC circuit are selected to provide a time constant that is similar to the time constant of the RC characteristics of the electrical load. 29. The method of claim 21, wherein the control signal comprises a pulse having a duration that begins when the input AC power voltage exceeds the predetermined voltage level and ends when the AC power voltage is less than the predetermined voltage level. 30. The method of claim 21, further comprising the steps of: rectifying the input AC power to providing a rectified power signal; andcharging a capacitor of a resistor-capacitor (RC) circuit when the rectified power signal exceeds the predetermined voltage leveldischarging the capacitor of the RC circuit when the rectified power signal is less than the predetermined voltage level, thereby providing a charging current pulse; andisolating the charging current pulse to provide the control signal. 31. The method of claim 30, further comprising the step of simulating the line impedance with a line impedance simulator circuit coupled to the diode bridge, whereby the line impedance simulator circuit and the RC circuit simulate the electrical characteristics of the electrical load. 32. The method of claim 30, wherein the control signal is a pulse that begins when the capacitor is charged to a first predetermined level and ends when the capacitor discharges to a second predetermined level. 33. The method of claim 21, wherein the relay control signal comprises a pulse of nominal duration of about 8.33 mS, and wherein the relay control signal is maintained at a value that keeps the relay in the closed position so long as the AC voltage peak detector circuit provides the control signal. 34. The method of claim 21, further comprising the step of maintaining the relay in the closed position so long as the relay control signal is maintained in a predetermined state. 35. The method of claim 21, wherein the relay is actuated by a semiconductor switch that is turned on by the relay control signal so as to maintain the relay in the closed position so long as the relay control signal is maintained. 36. The method of claim 21, wherein the control signal comprises signal pulses that correspond to the cycles of AC power from the input power supply, the signal pulses operative to retrigger a retriggerable pulse circuit during normal conditions on the input power supply, and further comprising the step of: maintaining the contacts in the closed position during provision of the control signal, whereby the relay contacts open if the signal pulses are not provided to retrigger the retriggerable pulse circuit. 37. The method of claim 21, wherein the method is carried out in a circuit coupled prior to a reactive load, and further comprising the steps of: maintaining the relay in an open position during an initial startup condition of power being provided from the input power supply, and placing the relay in the closed position after expiration of a predetermined time period after the startup condition. 38. The method of claim 37, further comprising the step of timing the predetermined time period after the startup condition with a timer circuit. 39. The method of claim 38, wherein the timer circuit comprises an inductor and resistor for simulating the startup characteristics of the electrical load and an resistor-capacitor (RC) circuit.
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