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US 6,856,096 B1Granted
Ballast with load-adaptable fault detection circuit
AssigneeOsram Sylvania Inc.
InventorAyan Kumar Choudhury
Life of this patent
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Abstract
A ballast (10) for powering a gas discharge lamp load (30) comprises an inverter (100), an output circuit (200), and a fault detection circuit (300). During operation, fault detection circuit (300) monitors a first signal and a second signal within output circuit (300) and sets a fault threshold in dependence on the second signal. The second signal is indicative of the type of lamps in the load (30). In response to the first signal exceeding the fault threshold, fault detection circuit (300) issues a shutdown command directing the inverter (100) to cease operation.
Claims15
A ballast, comprising:
- an inverter, comprising:
- first and second input terminals adapted to receive a source of substantially direct current (DC) voltage;
- an inverter output terminal;
- an output circuit coupled to the inverter output terminal, the output circuit comprising first and second output connections for coupling to a lamp load comprising at least one gas discharge lamp;
- a fault detection circuit coupled between the output circuit and the inverter, wherein the fault detection circuit is operable:
- (i) to monitor a first signal and a second signal within the output circuit;
- (ii) to set a fault threshold in dependence on the second signal;
- and
- (iii) in response to the first signal exceeding the fault threshold, to issue a shutdown command directing the inverter to cease operation.
6 more elements
A ballast, comprising:
- an inverter, comprising:
- first and second input terminals adapted to receive a source of substantially direct current (DC) voltage;
- an inverter output terminal;
- upper and lower inverter transistors;
- and
- an inverter driver circuit coupled to the upper and lower inverter transistors and operable to commutate the inverter transistors in a substantially complementary manner, the inverter driver circuit having a shutdown input wherein the inverter driver circuit is operable, in response to receipt of a shutdown command at the shutdown input, to cease commutating the inverter transistors;
- a fault detection circuit, comprising:
- first and second inputs;
- an output coupled to the shutdown input of the inverter driver circuit;
- an output circuit, comprising:
- first and second output connections for coupling to a lamp load comprising at least one gas discharge lamp;
- a resonant inductor coupled between the inverter output terminal and the first output connection, the first output connection being coupled to the first input of the fault detection circuit;
- and
- a resonant capacitor coupled between the first output connection and the second input of the fault detection circuit, the resonant capacitor having a resonant capacitor voltage and a resonant capacitor current;
- and
- wherein the fault detection circuit is operable:
- (i) to monitor the resonant capacitor voltage and the resonant capacitor current;
- (ii) to set a fault threshold in dependence on the resonant capacitor current;
- and
- (iii) in response to the resonant capacitor voltage exceeding the fault threshold, to send the shutdown command to the inverter driver circuit.
17 more elements
Dependencies are inferred from the claim text.