| 摘要 |
A ballast circuit for a single or multiple lamp parallel operation where at each lamp a condition may be controlled such that the amplitude of a resonant inductor current and an output voltage are almost constant in the steady state. The circuit consists of a half-bridge of a DC storage capacitor, a DC blocking capacitor, power transistors which alternately switch on and off and have a 50% duty ratio, and an LLC resonant converter having a resonant inductor and one or more resonant capacitors. The circuit also includes an output transformer providing galvanic isolation for a double path type power feedback scheme. The output transformer produces magnetizing inductance utilized for power feedback circuit optimization and is connected right after the resonant inductor of the half-bridge circuit.
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