| 摘要 |
A ballast circuit for an electrodeless lamp designed to use a phase dimmer signal to control output of the electrodeless lamp. Dimming ballast circuit includes a rectifier circuit for rectifying an input voltage from a phase dimmer source to generate a pulsed d.c. voltage on a d.c. bus. Ballast circuit further includes a converter control circuit coupled to the rectifier circuit for inducing an r.f. a.c. load current at approximately 2.5 MHz. The converter circuit includes first and second complementary converter switches serially connected between the bus and a reference node. The switches are connected together at a common node through which the a.c. load current flows. A driving inductor is connected at one end to the common node and operatively connected at the remaining end to the control node. A load circuit includes a resonant inductor connected at one end to the common node, with the resonant inductor mutually coupled to the driving inductor. An r.f. inductor is connected at one end to the remaining end of the resonant inductor for generating an r.f. field for powering the electrodeless lamp. A resonant capacitor is serially connected between the remaining end of the r.f. inductor and an intermediate node. All capacitors are dry-type capacitors. The pulsed d.c. voltage causes the lamp to restart at twice the power line frequency.
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