Lighting ballast having boost converter with on/off control and method of ballast operation
First Claim
1. An electronic ballast for driving a gas discharge lamp, comprising:
- a rectifier stage for receiving an alternating current (AC) input voltage from an AC supply to produce a rectified voltage having a peak voltage amplitude;
a boost converter stage for receiving the rectified voltage and for providing a direct current (DC) bus voltage having a DC magnitude;
the boost converter stage having an on state, in which the DC magnitude of the DC bus voltage is greater than the peak voltage amplitude of the rectified voltage, and an off state, in which the DC magnitude of the DC bus voltage is substantially equal to the peak voltage amplitude of the rectified voltage;
an inverter output stage for converting the DC bus voltage to a high-frequency AC output voltage to drive the lamp;
further comprising;
a control stage for receiving a desired light level signal representative of a desired light level of the lamp and for providing an output control signal to said boost converter stage;
wherein the boost converter stage changes between the on state and the off state dependent on the desired light level signal.
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Accused Products
Abstract
A ballast for driving a gas discharge lamp comprising a rectifier stage having an alternating current (AC) input and providing a rectified output voltage, a boost converter stage receiving the rectified output voltage as an input and providing a boosted direct current (DC) output voltage across a DC bus, an inverter output stage for converting the DC bus voltage to a high-frequency AC output voltage to drive the lamp, further comprising a control stage receiving a desired light level signal controlling the desired light level of the lamp and providing an output control signal for turning the boost converter stage on or off in dependency on the desired light level signal. The ballast thereby has reduced power consumption at low light levels for greater energy efficiency.
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Citations
43 Claims
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1. An electronic ballast for driving a gas discharge lamp, comprising:
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a rectifier stage for receiving an alternating current (AC) input voltage from an AC supply to produce a rectified voltage having a peak voltage amplitude; a boost converter stage for receiving the rectified voltage and for providing a direct current (DC) bus voltage having a DC magnitude;
the boost converter stage having an on state, in which the DC magnitude of the DC bus voltage is greater than the peak voltage amplitude of the rectified voltage, and an off state, in which the DC magnitude of the DC bus voltage is substantially equal to the peak voltage amplitude of the rectified voltage;an inverter output stage for converting the DC bus voltage to a high-frequency AC output voltage to drive the lamp; further comprising; a control stage for receiving a desired light level signal representative of a desired light level of the lamp and for providing an output control signal to said boost converter stage; wherein the boost converter stage changes between the on state and the off state dependent on the desired light level signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A ballast for driving a gas discharge lamp, comprising:
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an input stage operable to receive an alternating current (AC) input voltage having a peak voltage level and to provide a direct current (DC) bus voltage having a boosted voltage level that is greater than the peak voltage level of the AC input voltage; an output stage for converting the DC bus voltage into a high-frequency AC output voltage for driving the lamp; further wherein the input stage has a control input;
further comprising;a control stage responsive to a desired light level signal and having an output coupled to the control input of the input stage for sending an input stage control signal representative of a desired input stage mode of operation; wherein the input stage changes the DC bus voltage between the boosted voltage level and a reduced voltage level based on the input stage control signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method for reducing the power consumption of a ballast for driving a gas discharge lamp comprising the steps of:
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receiving an alternating current input voltage having a peak voltage level and providing a direct current output voltage having a boosted voltage level that is greater than the peak voltage level; converting the direct current output voltage into a high-frequency alternating current voltage in an output stage for driving the lamp; receiving a desired light level signal corresponding to a desired light level of the lamp and controlling the light level of the lamp based on the desired light level; and reducing the direct current output voltage from the boosted voltage level to a reduced voltage level when the desired light level signal is below a first predetermined desired light level. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification