High frequency operating circuit with in-rush current protection for operation of discharge lamps
US5719473A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 24, 1996 |
| Grant date | Feb 17, 1998 |
| Priority date | — |
| Expiry date | Oct 24, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H9/001
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An auxiliary or ballast circuit for high-frequency operation of discharge mps (E), for example sodium high pressure discharge lamps, provides for controlled inrush or "ON current" by including a thyristor (TH1) or pair of thyristors (TH2, TH3) in the current supply path to the discharge lamp (E) integrated into a combination active filter-voltage step-up circuit. The gate of the thyristor (TH1) or a pair of thyristors (TH2, TH3) is, or are, controlled over a resistance (R2, R3, R4) connected to the output capacitor (C2) of the filter-voltage step-up circuit to fire the thyristor when input voltage goes through null, and the output capacitor (C2) has a predetermined voltage level above the input voltage. The output capacitor (C2), before firing, is charged by a charge control resistor (R1) connected in parallel across the anode-cathode path of the thyristor or thyristors. Thus, a maximum controlled inrush current is provided independent of ambient temperature or temperature of a NTC resistor and not requiring a relay.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.