Energy management/dimming system and control
First Claim
1. A method for operating a dimming system connected to a fluorescent lighting system, said fluorescent lighting system including a ballast, fluorescent lamps and an AC source, said dimming system including a switch connected in series with said ballast and a dimming control circuit for controlling said switch, said dimming control circuit adapted to turn on and off said switch at a high frequency during a notch period within each half-cycle of current supplied to said ballast by said AC source and adapted to turn on said switch during the portions of each half-cycle outside of said notch period, the location and duration of said notch period being controlled by said dimming control circuit to provide a variable light output from said lighting system in response to a level command, said method comprising the steps of:
- (1) taking a plurality of current measurements, each measurement representing at least a portion of the current flowing to said ballast during a predetermined time period;
(2) averaging said plurality of measurements;
(3) calculating the error between said average and a command current reference corresponding to said level command; and
(4) altering said notch period to reduce said error.
1 Assignment
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Accused Products
Abstract
A fluorescent lamp dimming system which can be used in a retrofit manner with existing fluorescent lamp ballasts achieves a greater degree of energy management than has been previously possible. A dimming control having closed-loop feedback uses integrals of current as a measure of light output from the fluorescent lamps. The electronic control circuit implements complex control methods in a minimal space and at a minimal cost.
40 Citations
39 Claims
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1. A method for operating a dimming system connected to a fluorescent lighting system, said fluorescent lighting system including a ballast, fluorescent lamps and an AC source, said dimming system including a switch connected in series with said ballast and a dimming control circuit for controlling said switch, said dimming control circuit adapted to turn on and off said switch at a high frequency during a notch period within each half-cycle of current supplied to said ballast by said AC source and adapted to turn on said switch during the portions of each half-cycle outside of said notch period, the location and duration of said notch period being controlled by said dimming control circuit to provide a variable light output from said lighting system in response to a level command, said method comprising the steps of:
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(1) taking a plurality of current measurements, each measurement representing at least a portion of the current flowing to said ballast during a predetermined time period; (2) averaging said plurality of measurements; (3) calculating the error between said average and a command current reference corresponding to said level command; and (4) altering said notch period to reduce said error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A dimming control circuit in a fluorescent lamp dimming system, said dimming system being adapted to be connected to a fluorescent lighting system including a ballast, fluorescent lamps and an AC source, said dimming system including a switch for connecting in series with said ballast, said switch adapted to turn on and off at a high frequency during a notch period within each half-cycle of current supplied to said ballast by said AC source and adapted to turn on during the portions of each half-cycle outside of said notch period, said dimming control circuit comprising:
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signal processing means for coupling to said switch, said signal processing means providing a first output signal proportional to the instantaneous current flowing through said switch from said AC source to said ballast and a second output signal for indicating zero crossings of said instantaneous current; integrating means coupled to said signal processing means for integrating said first output signal to provide a current integral, the timing of the integration being provided according to said second output signal; comparing means coupled to said integrating means for comparing said current integral to a command current reference and providing an error value; timing means coupled to said signal processing means for receiving said second output signal and adapted to be coupled to said switch, said timing means for establishing said notch period and the high frequency switching of said switch during said notch period; and logic means coupled to said signal processing means, said comparing means and said timing means, said logic means adapted to receive a light level command signal, said logic means providing said command current reference to said comparison means based on said light level command signal, and said logic means providing counting values to said timing means based on said command current reference and said error value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A fluorescent lamp dimming system for connecting to a fluorescent lighting system, said lighting system including a ballast, fluorescent lamps and an AC source, said timming system comprising:
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a switch for connecting in series with said ballast, said switch adapted to turn on and off at a high frequency during a notch period within each half-cycle of current supplied to said ballast by said AC source and adapted to turn on during the portions of each half-cycle outside of said notch period; signal processing means coupled to said switch, said signal processing means providing a first output signal proportional to the instantaneous current flowing through said switch from said AC source to said ballast and a second output signal for indicating zero crossings of said instantaneous current; integrating means coupled to said signal processing means for integrating said first output signal to provide a current integral, the timing of the integration being provided according to said second output signal; comparing means coupled to said integrating means for comparing said current integral to a command current reference and providing an error value; timing means coupled to said signal processing means for receiving said second output signal and adapted to be coupled to said switch, said timing means including digital counters for establishing said notch period and the high frequency switching of said switch during said notch period; and logic means coupled to said signal processing means, said comparing means and said timing means, said logic means adapted to receive a light level command signal, said logic means providing said command current reference to said comparison means based on said light level command signal, and said logic means providing counting values to said digital counters based on said command current reference and said error value. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. A fluorescent lamp dimming system for connecting to a fluorescent lighting system, said lighting system including a ballast, fluorescent lamps and an AC source, said dimming system comprising:
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microprocessor means for controlling the operation of said dimming system, said microprocessor means including a clock, a stored program and data memory, said microprocessor means being responsive to an interrupt; a data bus connected to said microprocessor means; an address bus connected to said microprocessor means; a timing controller connected to said data bus and to said address bus, and coupled to said microprocessor means, said timing controller including a notch digital counter and a pulse digital counter, said notch digital counter adapted to generate a notch period, the output of said notch digital counter having a first output state during said notch period and having a second output state outside of said notch period, said pulse digital counter adapted to generate high frequency pulses during said notch period, the counting values of said notch and pulse digital counters being loaded by said microprocessor means via said data bus and said address bus; and interface means connected to said microprocessor means for receiving an externally supplied light level command and for providing said command to said microprocessor means. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36)
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37. A fluorescent lamp dimming system for connecting to a fluorescent lighting system, said lighting system including a ballast, fluorescent lamps and an AC source, said dimming system comprising:
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a switch for connecting in series with said ballast, said switch adapted to turn on and off at a high frequency during a notch period within each half-cycle of current supplied to said ballast by said AC source and adapted to turn on during the portions of each half-cycle outside of said notch period; a high voltage integrated circuit connected to said switch including a driver circuit for connecting to the control electrode of said switch, detector means for generating current zero signals, and current means for generating a current signal having a magnitude proportional to the instantaneous current flowing in said switch; a matrix chip connected to said high voltage integrated circuit including integrating means for integrating said current signal, notch timing means for generating said notch period, pulse means for generating pulses at said high frequency during said notch period, and logic gate means for combining the outputs of said notch timing means and said pulse means to generate a gate signal for coupling to said drive circuit; and a microprocessor connected to said matrix chip for controlling said matrix chip in accordance with a desired light level of said fluorescent lamps. - View Dependent Claims (38, 39)
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Specification