| 摘要 |
In a power-line-operated current-fed parallel-tuned electronic ballast, power-factor-correction and harmonics-reduction are attained by placing a high-frequency inductor as well as a high-frequeny voltage source in series with the DC output of a bridge rectifier connected with the power line voltage. The DC output is then supplied to a filter capacitor through a high-speed diode, thereby to provide a DC voltage of substantially constant magnitude to the ballast's inverter while at the same time drawing power from the power line with a power factor well over 90% and with a total harmonics content well under 20%. The AC voltage provided from the high-frequency voltage source, which has a peak-to-peak magnitude essentially equal to that of the power line voltage, is represented by a simple auxiliary winding on the ballast's main output transformer. The inductance of the high-frequency inductor is determined by the frequency of the ballast's AC output voltage as well as by the amount of power drawn from the power line.
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