Sensing and balancing currents in a ballast dimming circuit
AssigneeTridonic-USA, Inc.
InventorsHubertus Notohamiprodjo, Thomas Marinelli
Life of this patent
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Abstract
The present invention is directed to accurately sensing and regulating lamp current, and thus lamp output, over a range of lamp outputs, down to and below 10% of total lamp output. Exemplary embodiments can be used with a single set of power elements to drive multiple lamps in either an isolated or a non-isolated condition.
Claims20
Apparatus for controlling a ballast circuit comprising:
- means for sensing current at each of multiple outputs of a ballast circuit which is configured to receive current of each lamp to be driven, wherein first and second outputs from the ballast circuit are provided for connecting to a first lamp and third and fourth outputs from the ballast circuit are provided for connecting to a second lamp;
- and
- means for balancing current among each of the multiple outputs, using at least one magnetically coupled winding to balance current among each of said multiple outputs, wherein said magnetically coupled winding is formed in a transformer having at least first and second transformer windings.
A ballast circuit comprising:
- first and second outputs from the ballast circuit for connecting to a first lamp;
- third and fourth outputs from the ballast circuit for connecting to a second lamp;
- a first winding within a first current path for the first and second output;
- a second winding within a second current path for the third and fourth output;
- and
- wherein the first and second windings are magnetically coupled for balancing currents of the first and second current paths.
The ballast circuit according to claim, 14, wherein the ballast circuit is a six wire ballast.
Method for controlling a ballast, wherein first and second outputs from the ballast circuit are provided for connecting to a first lamp and third and fourth outputs from the ballast circuit are provided for connecting to a second lamp, the method comprising the steps of:
- sensing current at each of multiple outputs of a ballast circuit which is configured to receive current of each lamp to be driven;
- and
- balancing current among each of said multiple outputs, using at least one magnetically coupled winding to balance current among each of said multiple outputs, wherein said magnetically coupled winding is formed in a transformer having at least first and second transformer windings.
Dependencies are inferred from the claim text.