Electronically power-factor-corrected ballast

Details Electronically power-factor-corrected ballast Electronically power-factor-corrected ballast

1990-08-20

1992-05-19

LaRoche, Eugene R.

Electric lamp and discharge devices: systems

Pulsating or a.c. supply

With power factor control device

315906, 315272, H05B 4124

Patent

active

051153475

ABSTRACT:
A fluorescent lamp is connected in parallel with the tank capacitor of a resonant L-C circuit series-excited by a 30 kHz voltage from a self-oscillating inverter. The inverter's DC supply voltage is at certain times obtained directly from unfiltered full-wave-rectified 120 Volt/60 Hz power line voltage and at certain other times from an energy-storing capacitor kept charged to a given voltage level by up-conversion from the unfiltered full-wave-rectified rectified power line voltage. The up-conversion is accomplished via a FET transistor switched at 30 kHz with a gate-drive derived from the L-C circuit. Whenever the magnitude of the DC supply voltage exceeds a predetermined level, the gate-drive voltage ceases to be provided and the up-conversion process ceases. Whenever up-conversion does take place, the magnitude of the current drawn from the power line is proportional to the instantaneous magnitude of the power line voltage. To maximize overall efficiency, while maintaining high power factor, low total harmonic distortion and low lamp current crest factor, the inverter's DC supply voltage is supplied directly from the power line whenever the instantaneous magnitude of the power line voltage exceeds about 120 Volt and via the up-converter in combination with the energy-storing capacitor whenever the instantaneous magnitude of the power line voltage is below 120 Volt.

REFERENCES:
patent: 4251752 (1981-02-01), Stolz
patent: 4277726 (1981-07-01), Burke
patent: 4277728 (1981-07-01), Stevens
patent: 4388561 (1983-06-01), Koshimura et al.
patent: 4538095 (1985-08-01), Nilssen

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