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US 6,856,100 B1Granted
Ballast with inverter startup circuit
AssigneeOsrom Sylvania, Inc.
InventorJohn G. Konopka
Life of this patent
Estimating the term…
Abstract
A ballast (20, 20′) includes a rectifier circuit (100), a boost converter (200, 200′), an inverter (300), an output circuit (400), and an inverter startup circuit (600). Inverter startup circuit (600) is coupled between boost converter (200) and inverter (300). During operation, inverter startup circuit (600) provides a delay period between startup of boost converter (200) and startup of inverter (300) so that startup of inverter (300) is delayed until at least such time as the DC rail voltage provided by boost converter (200) approaches its steady-state operating level. This ensures that the ballast (20,20′) provides an output voltage that is sufficiently high to ignite a lamp (40) in a preferred manner, with little or no glow current and a fast strike time.
Claims20
An electronic ballast, comprising:
- a rectifier circuit adapted to receive a source of alternating current (AC) line voltage, the AC line voltage having a magnitude;
- a boost converter coupled to the rectifier circuit and operable to provide a substantially direct current (DC) rail voltage having a steady-state operating level;
- an inverter coupled to the boost converter;
- an output circuit coupled to the inverter and operable to provide power to at least one gas discharge lamp;
- an inverter startup circuit coupled between the boost converter and the inverter, wherein the inverter startup circuit is operable to provide a delay period between startup of the boost converter and startup of the inverter such that startup of the inverter is delayed until at least such time as the DC rail voltage approaches its steady-state operating level.
2 more elements
An electronic ballast, comprising:
- a rectifier circuit adapted to receive a source of alternating current (AC) line voltage;
- a boost converter operable to provide a substantially direct current (DC) rail voltage having a steady-state operating level, the boost converter comprising:
- first and second input terminals coupled to the rectifier circuit;
- first and second output terminals, the second output terminal being coupled to second input terminal;
- a boost transistor having a first conduction terminal, a second conduction terminal, and a control terminal, wherein the second conduction terminal is coupled to the second input terminal;
- a boost control circuit coupled to the control terminal of the boost transistor and operable to commutate the boost transistor;
- a boost inductor having a primary winding coupled between the first input terminal and the first conduction terminal of the boost transistor;
- a boost rectifier having an anode and a cathode, wherein the anode is coupled to the first conduction terminal of the boost transistor and the cathode is coupled to the first output terminal;
- and
- a bulk capacitor coupled between the first and second output terminals;
- an inverter, comprising:
- first and second input terminals coupled to the first and second output terminals of the boost converter;
- an inverter output terminal coupled to the output circuit;
- an upper inverter transistor coupled between the first input terminal and the output terminal;
- a lower inverter transistor coupled between the output terminal and circuit ground;
- a drive circuit for the upper transistor;
- and
- a drive circuit for the lower transistor;
- an output circuit coupled to the inverter and operable to provide power to at least one gas discharge lamp;
- an inverter startup circuit operable to delay starting the inverter until at least such time as the boost converter begins to operate and the DC rail voltage approaches its steady-state operating level, the inverter startup circuit comprising:
- an input terminal coupled to the boost converter;
- a first output terminal coupled to the drive circuit for the lower transistor;
- and
- a second output terminal coupled to the inverter output terminal.
21 more elements
An electronic ballast, comprising:
- a rectifier circuit adapted to receive a source of alternating current (AC) line voltage;
- a boost converter, comprising:
- first and second input terminals coupled to the rectifier circuit;
- first and second output terminals, the second output terminal being coupled to the second input terminal;
- a boost transistor having a first conduction terminal, a second conduction terminal, and a control terminal, wherein the second conduction terminal is coupled to the second input terminal;
- a boost control circuit coupled to the control terminal of the boost transistor and operable to commutate the boost transistor;
- a boost inductor having a primary winding coupled between the first input terminal and the first conduction terminal of the boost transistor;
- a boost rectifier having an anode and a cathode, wherein the anode is coupled to the first conduction terminal of the boost transistor and the cathode is coupled to the first output terminal;
- and
- a bulk capacitor coupled between the first and second output terminals;
- an inverter, comprising:
- first and second input terminals coupled to the first and second output terminals of the boost converter;
- an inverter output terminal coupled to the output circuit;
- an upper inverter transistor coupled between the first input terminal and the output terminal;
- a lower inverter transistor coupled between the output terminal and circuit ground;
- a drive circuit for commutating the upper and lower inverter transistors in a substantially complementary manner;
- an output circuit coupled to the inverter and operable to provide power to at least one gas discharge lamp;
- and
- an inverter startup circuit, comprising:
- an input terminal coupled to the boost converter;
- a first output terminal coupled to the drive circuit of the inverter;
- a second output terminal coupled to the inverter output terminal;
- a first capacitor coupled between the input terminal and a first node;
- a resistor coupled between the first node and a second node;
- a first diode having an anode coupled to circuit ground and a cathode coupled to the second node;
- a second diode having an anode coupled to the second node and a cathode coupled to a third node;
- a second capacitor coupled between the third node and circuit ground;
- a diac coupled between the third node and the first output terminal;
- and
- a third diode having an anode coupled to the third node and a cathode coupled to the second output terminal.
27 more elements
Dependencies are inferred from the claim text.