| 摘要 |
An inverter is powered from a DC voltage whose instantaneous absolute magnitude is equal to that of the AC power line voltage except for being prevented from falling below a level equal to half the peak of the power line voltage. The inverter's output is loaded via a series-tuned high-Q LC circuit. Two fluorescent lamps are loading the secondary winding of a transformer whose primary winding is connected across the capacitor of the LC circuit. The magnitude of the voltage present across the capacitor is normally limited by the loading of the fluorescent lamps. However, with the lamps removed, if not expressly prevented from doing so, the magnitude of the voltage across the capacitor will increase to a destructive level due to Q-multiplication. To prevent this, an auxiliary winding on the transformer is used for limiting the magnitude for the voltage across the capacitor by rectifying the output from the auxiliary winding and feeding the resulting DC to the inverter's input; whereby the magnitude of the voltage across the capacitor will be limited to a level determined by the instantaneous magnitude of the DC voltage; which level is set such as to result in acceptable lamp starting while at the same time preventing any voltage-limiting from taking place at any time as long as the lamps are operating.
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