Method and Apparatus for Measuring Operating Characteristics in a Load Control Device
First Claim
1. A load control device for controlling the power delivered from an AC power source to an electrical load, the load control device comprising:
- a power converter for generating a DC bus voltage, the power converter comprising an inductor and a power switching device coupled to the inductor, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive, the power switching device controlled to be conducive for an on time;
a load control circuit receiving the bus voltage and adapted to be coupled to the electrical load for controlling the power delivered to load; and
a control circuit operatively coupled to the load control circuit for controlling the power delivered to the lamp, the control circuit receiving a control signal representative of an instantaneous magnitude of an AC line voltage of the AC power source, the control circuit operatively coupled to the power switching device of the power converter for controlling the length of the on time;
wherein the control circuit is operable to calculate an average input power of the load control device using the on time, the instantaneous magnitude of the AC line voltage, and an inductance of the inductor of the power converter.
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Accused Products
Abstract
A load control device, such as an electronic ballast, for controlling the power delivered from an AC power source to an electrical load, such as one or more fluorescent lamps, comprises a power converter having an inductor and a power switching device coupled to the inductor, a load control circuit adapted to be coupled to the electrical load, and a control circuit operable to calculate an average input power of the load control device. The control circuit may be operable to calculate a cumulative output power of the power converter while the ballast is preheating filaments of the lamps, and to subsequently determine a fault condition in the lamps in response to the calculated cumulative output power of the power converter. Further, the control circuit may be operable to transmit a digital message including the calculated average input power of the load control device.
57 Citations
26 Claims
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1. A load control device for controlling the power delivered from an AC power source to an electrical load, the load control device comprising:
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a power converter for generating a DC bus voltage, the power converter comprising an inductor and a power switching device coupled to the inductor, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive, the power switching device controlled to be conducive for an on time; a load control circuit receiving the bus voltage and adapted to be coupled to the electrical load for controlling the power delivered to load; and a control circuit operatively coupled to the load control circuit for controlling the power delivered to the lamp, the control circuit receiving a control signal representative of an instantaneous magnitude of an AC line voltage of the AC power source, the control circuit operatively coupled to the power switching device of the power converter for controlling the length of the on time; wherein the control circuit is operable to calculate an average input power of the load control device using the on time, the instantaneous magnitude of the AC line voltage, and an inductance of the inductor of the power converter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An electronic ballast for driving one or more gas discharge lamps from an AC power source, the ballast comprising:
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a boost converter for generating a DC bus voltage, the boost converter comprising an inductor and a power switching device coupled to the inductor, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive, the power switching device controlled to be conducive for an on time; an inverter circuit for converting the bus voltage to a high-frequency AC voltage; a resonant tank for coupling the high-frequency AC voltage to the lamps; a control circuit operatively coupled to the load control circuit for controlling the power delivered to the lamps, the control circuit receiving a control signal representative of an instantaneous magnitude of an AC line voltage of the AC power source, the control circuit operatively coupled to the power switching device of the boost converter for controlling the length of the on time; wherein the control circuit is operable to calculate a cumulative output power of the boost converter while the ballast is preheating filaments of the lamps using the on time, the instantaneous magnitude of the AC line voltage, and an inductance of the inductor of the boost converter, the control circuit operable to determine a fault condition in the lamps in response to the cumulative output power calculated while the ballast circuit is preheating filaments of the lamps. - View Dependent Claims (21, 22, 23, 24, 25)
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19. An electronic ballast for driving a gas discharge lamp from an AC power source, the ballast comprising:
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a boost converter for generating a DC bus voltage, the boost converter comprising an inductor and a power switching device coupled to the inductor, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive, the power switching device controlled to be conducive for an on time; an inverter circuit for converting the bus voltage to a high-frequency AC voltage; a resonant tank for coupling the high-frequency AC voltage to the lamp; a control circuit operatively coupled to the load control circuit for controlling the power delivered to the lamp, the control circuit receiving a control signal representative of an instantaneous magnitude of an AC line voltage of the AC power source, the control circuit operatively coupled to the power switching device of the boost converter for controlling the length of the on time; and a communication circuit coupled to the control circuit for transmitting and receiving digital message; wherein the control circuit is operable to calculate an average input power of the ballast using the on time, the instantaneous magnitude of the AC line voltage, and an inductance of the inductor of the boost converter, the control circuit operable to transmit a digital message including the calculated average input power of the ballast via the communication circuit.
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20. A method of detecting a fault condition in one or more gas discharge lamps driven by an electronic ballast, the ballast comprising a boost converter having an inductor and a power switching device coupled to the inductor, the method comprising:
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selectively rendering the power switching device conductive and non-conductive to generate a DC bus voltage, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive; adjusting the length of an on time for which the power switching device is conductive; converting the bus voltage to a high-frequency AC voltage; coupling the high-frequency AC voltage to the lamps; preheating filaments of the lamps prior to attempting to strike the lamps; calculating a cumulative output power of the boost converter while preheating filaments of the lamps by using the on time, an instantaneous magnitude of an AC line voltage of the AC power source, and an inductance of the inductor of the boost converter; and detecting the fault condition in the lamps in response to the cumulative output power calculated while preheating filaments of the lamps.
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26. A method of transmitting a digital message from a load control device for controlling the power delivered from an AC power source to an electrical load, the load control device comprising a power converter having an inductor and a power switching device coupled to the inductor, the method comprising:
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selectively rendering the power switching device conductive and non-conductive to generate a DC bus voltage, such that the inductor is operable to charge when the power switching device is conductive and to discharge when the power switching device is non-conductive; adjusting the length of an on time for which the power switching device is conductive; converting the bus voltage to a high-frequency AC voltage; coupling the high-frequency AC voltage to the lamps; calculating an input power of the boost converter using the on time, an instantaneous magnitude of an AC line voltage of the AC power source, and an inductance of the inductor of the boost converter; and transmitting a digital message including the calculated average input power of the load control device.
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Specification