High frequency transformerless electronics ballast using double inductor ...

United States Patent m

Lai

US0O5426350A

[11] Patent Number: [45] Date of Patent:

5,426,350 Jun. 20, 1995

[54] HIGH FREQUENCY TRANSFORMERLESS ELECTRONICS BALLAST USING DOUBLE INDUCTOR-CAPACITOR RESONANT POWER CONVERSION FOR GAS DISCHARGE LAMPS

[75] Inventor: Jih-Sheng Lai, Knoxville, Tenn.

[73] Assignee: Electric Power Research Institute, Inc., Palo Alto, Calif.

[21] Appl. No.: 154,762

[22] Filed: Not. 18,1993

[51] Int. Cl.« H05B 37/00

[52] U.S. CI 315/244; 315/291;

315/307; 315/308; 315/209 R; 315/DIG. 2;

315/227 R

[58] Field of Search 315/291, 219, 209 R,

315/244, 227, 307, 308, DIG. 2

[56] References Cited

U.S. PATENT DOCUMENTS

3,619,716 11/1971 Spira et al 315/244

4,572,991 2/1986 Cote 315/240

4,818,918 4/1989 Murphy 315/244

4,859,914 8/1989 Summa 315/354

4,933,605 6/1990 Quazi 315/224

4,958,108 9/1990 Jorgensen 315/307

4,999,547 3/1991 Ottenstein 315/307

5,028,846 7/1991 Lesea 315/219

5,049,789 9/1991 Kumar et al 315/289

5,051,665 9/1991 Garrison 315/287

5,057,752 10/1991 Grabner et al 315/289

A novel high frequency LCLC double resonant electronic ballast has been developed for gas discharge lamp applications. The ballast consists of a half-bridge inverter which switches at zero voltage crossing and an LCLC resonant circuit which converts a low ac voltage to a high ac voltage. The LCLC resonant circuit has two LC stages. The first LC stage produces a high voltage before the lamp is ignited. The second LC stage limits lamp current with the circuit inductance after the lamp is ignited. In another embodiment a filament power supply is provided for soft start up and for dimming the lamp. The filament power supply is a secondary of the second resonant inductor.

14 Claims, 13 Drawing Sheets

MAGNITUDE

Vout/Vin

9.00 8.00 7.00 6.00 5.00 4.00 3.00 2.00 1.00 0.001

1.00e+04

1.00e+05

1.00e+06