Fault protection system and method for fluorescent lamp ballasts
AssigneeGeneral Electric Company
InventorsGang YAO, James Domenic MIESKOSKI
Life of this patent
Estimating the term…
Abstract
Provided is a lighting ballast system and method for fluorescent lamps. The system and method utilize a lamp current control loop to control the light level of a fluorescent lamp. The ballast includes an open loop detector that recognizes an open current control loop as an indication of a fault or hazard condition, and causes the ballast to output a safe lamp voltage or no voltage. The fault or hazard condition may be, for example, a very high voltage at the lamp or very low current across the lamp. The ballast also includes a disable circuit that prevents the open loop detector from triggering at times when the loop is expected to be open such as during ignition and maintenance restarting of the lamp.
Claims20
A lighting system, comprising:
- a ballast inverter having a frequency controller, the ballast inverter providing a voltage to a lamp;
- a summing junction in communication with a current detector and a current command interface, the summing junction determining an error between a first output and a second output and providing a third output to the frequency controller;
- a current detector in communication with the lamp and the summing junction, the current detector determining a current across the lamp and providing a first output to the summing junction;
- a current command interface in communication with the summing junction, the current command interface providing a second output to the summing junction;
- and
- an open loop detector in communication with the summing junction and the frequency controller, the open loop detector receiving the third output from the summing junction and determining whether a fault condition exists.
A lighting system, comprising:
- a lamp current control loop configured to regulate the current applied to a lamp, the lamp current control loop comprising:
- a ballast inverter in communication with a frequency controller and a lamp, the ballast inverter being configured to provide a voltage to the lamp;
- the frequency controller in communication with the ballast inverter, the frequency controller being configured to adjust the frequency of the ballast inverter;
- a current detector in communication with the lamp and an amplifier, the current detector being configured to determine a current through the lamp and provide a current feedback to the amplifier;
- a dimming command interface in communication with the amplifier, the dimming command interface being configured to control the level of brightness of the lamp;
- and
- the amplifier receiving a first input from the current detector and a second input from the dimming command interface, the amplifier being configured to detect an error between the first input and the second input;
- and
- an open loop detector in communication with the amplifier and the frequency controller, the open loop detector being configured to receive a third output from the amplifier and determine whether a fault condition exists based on the third output.
The lighting method, comprising:
- providing a voltage to a lamp, the lamp comprising fluorescent lamps;
- determining a current across the lamp;
- providing an output based on the current across the lamp;
- providing an output based on a light setting, wherein the light setting may indicate a desired light level of the lamp;
- determining the difference between the current across the lamp and the desired light level of the lamp;
- determining whether a fault or hazard condition exists based on the difference between the current across the lamp and the desired light level;
- controlling, when a fault or hazard condition is determined, the current across the lamp to go to a safe level or to be cut off;
- and
- controlling, when no fault or hazard condition is determined, a voltage frequency applied to the lamp based on the determined difference between the current across the lamp and the desired current level.
Dependencies are inferred from the claim text.