High frequency electronic ballast for multiple lamp independent operation
US6326740A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1998 |
| Grant date | Dec 4, 2001 |
| Priority date | — |
| Expiry date | Dec 22, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S315/07
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An electronic ballast with a voltage-fed, LC or LLC resonant inverter for multiple gas discharge lamp independent operation which maintains a substantially constant voltage to a lamp or lamps connected to the ballast even during a transition period when a lamp or lamps is ignited, extinguished, added or removed. The ballast includes a feedback loop that maintains a substantially constant phase angle between the voltage and the current in an LC or LLC tank circuit, which has the effect of the ballast providing the substantially constant voltage output. The feedback loop obtains a current feedback signal and a voltage feedback signal from the tank circuit, and provides a phase shifted signal as a feedback correction signal which is the current feedback signal phase shifted by the voltage feedback signal that tracks phase angle changes with one, some or all of the lamps of a set thereof connected to the ballast, and during the transition period. The feedback loop includes a phase-shift circuit which includes at least one differential amplifier stage that receives the current feedback signal at both inputs and the voltage feedback signal at one input so as to phase shift the current fe…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.