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US 7,923,941 B2Granted
Low cost compact size single stage high power factor circuit for discharge lamps
AssigneeGeneral Electric Company
InventorsTimothy Chen, Virgil A. Chichernea, James K. Skully
Life of this patent
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Abstract
The present application claims a compact low cost topology solution of a ballast for a discharge lamp that can provide both high power factor and low total harmonic distortion with fewer components than prior art. The topology provides the feature of a low crest factor and quick start that increase both the lamp life and the number of starts for the product. By using Bipolar Junction Transistor instead of Field Effect Transistor as the main switches and also a lower value electrolytic, the cost and size are considerably reduced.
Claims20
A ballast circuit or driving a discharge lamp, comprising:
- a power input operative to receive an AC input signal;
- a rectifier comprising a rectifier input including first and second rectifier input terminals coupled with the power input, a rectifier output coupled to first and second terminals of a DC bus, and at least one rectifier diode coupled between the rectifier input and the rectifier output and operative to convert AC power at the rectifier input to provide DC power to the DC bus;
- an inverter including first and second Bipolar Junction Transistors (BJTs) coupled in series between the first and second DC bus terminals, the first and second BJTs connected to one another at an inverter central node;
- a transformer with a primary winding coupled between the inverter central node and a first lamp connection, and first and second secondary windings;
- a driver circuit including the first and second secondary windings of the transformer, the first secondary winding of the transformer being coupled with a base terminal of the first BJT, and the second secondary winding of the transformer being coupled with a base terminal of the second BJT, the driver circuit operative to drive the first and second BJTs in alternating fashion to provide a high frequency AC inverter output signal at the inverter central node;
- a first capacitance coupled in series between the first lamp connection and the first rectifier input terminal;
- and
- a second capacitance coupled in series between a second lamp connection and the second rectifier input terminal.
5 more elements
A ballast circuit for driving a discharge lamp, comprising:
- a power input operative to receive an AC input signal;
- a rectifier comprising a rectifier input including first and second rectifier input terminals coupled with the power input, a rectifier output coupled to first and second terminals of a DC bus, and at least one rectifier diode coupled between the rectifier input and the rectifier output and operative to convert AC power at the rectifier input to provide DC power to the DC bus;
- an inverter including first and second Bipolar Junction Transistors (BJTs) coupled in series between the first and second DC bus terminals, the first and second BJTs connected to one another at an inverter central node;
- an inductance coupled between the inverter central node and a first lamp connection;
- a transformer with a primary winding coupled between second and third lamp connections, and first and second secondary windings;
- a driver circuit including the first and second secondary windings of the transformer, the first secondary winding of the transformer being coupled with a base terminal of the first BJT, and the second secondary winding of the transformer being coupled with a base terminal of the second BJT, the driver circuit operative to drive the first and second BJTs in alternating fashion to provide a high frequency AC inverter output signal at the inverter central node;
- a first capacitance coupled in series between the first lamp connection and the first rectifier input terminal;
- and
- a second capacitance coupled in series between a fourth lamp connection and the second rectifier input terminal.
6 more elements
A ballast circuit for driving a discharge lamp, comprising:
- a power input operative to receive an AC input signal;
- a rectifier comprising a rectifier input including first and second rectifier input terminals coupled with the power input, a rectifier output coupled to first and second terminals of a DC bus, and at least one rectifier diode coupled between the rectifier input and the rectifier output and operative to convert AC power at the rectifier input to provide DC power to the DC bus;
- an inverter including first and second Bipolar Junction Transistors (BJTs) coupled in series between the first and second DC bus terminals, the first and second BJTs connected to one another at an inverter central node, the inverter central node coupled with a first lamp connection;
- a driver circuit operative to drive the first and second BJT's in alternating fashion to provide a high frequency AC inverter output signal at the inverter central node;
- a first capacitance directly connected in series between the first lamp connection and the first rectifier input terminal;
- and
- a second capacitance directly connected in series between a fourth lamp connection and the second rectifier input terminal.
4 more elements
Dependencies are inferred from the claim text.