Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Patent
1993-11-24
1995-05-16
Pascal, Robert J.
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
315219, 315291, 315307, 315308, 315247, 363 16, H05B 3702
Patent
active
054163870
ABSTRACT:
A gas discharge lamp ballast provides near unity power factor simultaneously with high-frequency lamp ballasting in a single switching power conversion stage resulting in efficiency improvements, reduction in size and weight and reduced component count and cost. The single conversion stage comprises a fast-recovery diode connecting in series the input inductor, energy transfer capacitor and the resonant matching network, and switching means alternately connecting the first junction between the input inductor and energy transfer capacitor, or the second junction between the matching network and the other side of said capacitor to the return current path. The switching means comprises two current bidirectional switches driven out of phase, thus producing a square-wave high frequency voltage source, which is in turn converted by the resonant matching network into a sine-wave ac current source required by the gas discharge lamp. The fast-recovery input diode in conjunction with the input inductance chosen to be less than the critical inductance value forces the input inductor current into a new discontinuous inductor current mode (DICM). The average input inductor current is shown to closely follow the rectified line voltage when the ballast is operated at the constant duty ratio and at the constant switching frequency either open-loop or with the slow feedback loop of conventional PWM control. Zero voltage switching for the two current bidirectional switches is achieved by introducing two transition intervals during which both switches are OFF and utilizing the negative value of the lagging current of the matching network above resonance.
REFERENCES:
patent: 4184197 (1980-01-01), Cuk et al.
E. E. Hammer, "Fluorescent Lamp Operating Characteristics at High Frequency", Journal of IES, Oct. 1984.
P. Wood, "High Frequency Discharge Lamp Ballasts Using Power MOSFETs, IGBT's and High Voltage Monolithic Drives", PCI Proceedings, pp. 307-324, 1989.
J. Spangler, et al., "Electronic Ballast Using a Power Factor Correction Techniques for Loads Greater Than 300 Watts", APEC 91, pp. 393-399, Mar. 1991.
S. D. Freeland, "Input Current Shaping for Single-Phase AC-DC Power Converters", Ph.D. Thesis, Part II, California Institute of Technology, 1988.
R. L. Steigerwald, "High Frequency Resonant Transistor DC-DC Converters", IEEE Trans. on IE, vol. IE-31, No. 2, May 1984.
Cuk Slobodan
Deng Er
California Institute of Technology
Fernandez Antonio M.
Pascal Robert J.
Ratliff Reginald A.
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