High intensity discharge lamp ballast
First Claim
1. A high intensity discharge lamp ballast circuit comprising:
- first and second lamp terminals operable to receive a high intensity discharge lamp between the first and second lamp terminals;
a first inductor connected with the first lamp terminal;
a first capacitor connected with the first inductor and the second lamp terminal;
a second capacitor connected with the first lamp terminal; and
second and third inductors connected with the first inductor and the first capacitor.
1 Assignment
0 Petitions
Accused Products
Abstract
A low current loss ballast operates a high intensity discharge lamp with or without radioactive krypton. A by-pass capacitor in conjunction with a resonant strike circuit limits high frequency ripple applied to a lamp during continuing operation. Different resistor combinations are connected to drive dual buck converters of the ballast. One combination is used for high frequency operation for striking. Another combination is used during low frequency operation to limit current loss. In a strike mode of operation, combinations of signals at a resonant frequency for striking and subharmonic frequencies are applied to a resonant circuit. The signals at the subharmonic have less than a 50% duty cycle.
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Citations
29 Claims
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1. A high intensity discharge lamp ballast circuit comprising:
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first and second lamp terminals operable to receive a high intensity discharge lamp between the first and second lamp terminals; a first inductor connected with the first lamp terminal; a first capacitor connected with the first inductor and the second lamp terminal; a second capacitor connected with the first lamp terminal; and second and third inductors connected with the first inductor and the first capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of powering a high intensity discharge lamp connected between first and second lamp terminals of a lamp ballast circuit, the method comprising the steps of:
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in a first mode, operating first and second switches alternately at a first switching frequency so as to cause resonance in first, second and third inductors and a first capacitor, the resonance operable to generate a strike voltage between the first and second lamp terminals; and subsequently, in a second mode, while the lamp continues to conduct, operating the first and second switches alternately at a second switching frequency that is lower than the first frequency so as not to cause resonance, and using a second capacitor to divert high frequency ripple current away from the lamp. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method of striking a high intensity discharge lamp, the method comprising the steps of:
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supplying a first alternating signal to lamp terminals at a first subharmonic of a first resonant frequency and with a less than 50% duty cycle; and supplying a second alternating signal to the lamp terminals at the first resonant frequency. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. A high intensity discharge lamp ballast circuit comprising:
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first and second performance switches; first and second main switches; first and second lower value resistors connected between the first and second performance switches and the first and second main switches, respectively; first and second higher value resistors connected with the first and second main switches, respectively; and a controller operable to cause the first and second main switches to operate at lower and higher frequencies, to cause the first and second performance switches to connect the first and second lower value resistors in parallel with the first and second higher value resistors, respectively, at the higher frequencies, and to cause the first and second performance switches to disconnect the lower value resistors at the lower frequencies. - View Dependent Claims (27, 28)
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29. A high intensity discharge lamp ballast circuit comprising:
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dual buck converters operable in a first mode as substantially zero current switches and operable in a second mode with a higher frequency; a resonant strike circuit connected with a first lamp terminal and the dual buck converters; and a by-pass capacitor connected between the dual buck converters and a second lamp terminal.
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Specification