| 摘要 |
In an electronic ballast for powering three series-connected fluorescent lamps with a 30 kHz lamp current, a half-bridge series-resonance-type inverter circuit is powered from a substantially constant-magnitude DC supply voltage derived from ordinary 60 Hz power line voltage by way of a bridge rectifier and a single-transistor DC-to-DC converter using an energy-storing inductor with an isolated secondary winding from which the DC supply voltage is derived. Thus, the DC supply voltage is electrically isolated from the power line, as is also the inverter circuit itself as well as the ballast's output terminals. Lamp dimming is accomplished via a dimming control directly connected with the inverter circuit.
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