| 摘要 |
A half-bridge inverter is powered from a constant-magnitude DC supply voltage and provides at the inverter's output a first AC output voltage that is describable as a modified squarewave voltage. This first AC voltage is applied across a series-combination of a tank inductor and a tank capacitor, the junction between which is clamped to the DC supply voltage. As a result, a second AC voltage gets established across the tank capacitor; which second AC voltage is also describable as a modified squarewave voltage. However, the phasing of the second AC voltage is delayed by roughly 90 DEG degrees with respect to the first AC voltage; which results in the voltage across the tank inductor being of approximately sinusoidal waveform. A first and a second fluorescent lamp is connected in series with a first and a second ballast capacitor, respectively; and the two lamp-capacitor series-combinations are parallel-connected across the inductor, thereby resulting in an approximately sinusoidal current being provided to the lamps. To provide for enhanced instant-start lamp ignition, an auxiliary capacitor is connected across the tank capacitor for the initial 100 milli-seconds; which has the effect of providing more power to the lamps during the brief ignition period.
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