| 摘要 |
An air gapped inductance and a capacitance form a series resonance that is itself in series with a flourescent tube. The resulting series resonant network is permanently connected to one (+) side of the DC supply, while the other end is switched between that (+) side of the DC supply and the other (-) side of the DC supply. Switching occurs in synchronism with the different polarities of the half-cycles for the current circulating in the resonant circuit. In series with the current in the resonant circuit is the primary of a phase splitter driver transformer having separate secondaries phased to control FET switches to do the aforementioned switching, and whose turns ratios are selected to determine the duty cycles with which the resonant circuit is switched. The switched end is connected to the one (+) end of the DC supply for its entire associated half cycle. For significantly less than the remaining half cycle it is switched to the other (-) side of the DC supply to restore energy to the circuit and replace that which has been dissipated in the flourescent lamp. During the remaining balance of that remaining half cycle neither FET switch is closed, and current flows through a diode that bypasses the FET that is connected to the + side of the DC supply.
|
