| 摘要 |
<p>A condensed power supply circuit for powering a gas discharge lamp (300) with bi-directional current reduces duty cycle by increasing dead time. The circuit comprises an arrangement for supplying d.c. power from an a.c. voltage, a series half bridge converter, a boost converter, a resistor-capacitor delay circuit (372,374) associated with a gate to control dead time, and a snubber capacitance (370) for facilitating zero voltage switching to fill the entire dead time. The series half-bridge converter alternately impresses a d.c. bus voltage from a bus conductor across a load circuit first with one polarity and then with an opposite polarity. The series half-bridge converter includes a first switch (S1), a second switch (S2), and a switching control circuit (332) for alternately switching on the first and second switches. The boost converter comprises a boost capacitor (CS1,CS2), a boost inductor (LB), and means for periodically connecting a load end of the boost inductor through a low impedance path to the ground conductor, thereby charging the boost inductor. The present invention reduces duty cycle via an increase in dead time. The resistor-capacitor delay circuit, associated with a gate, is used to control dead time. The snubber capacitance (370), which facilitates zero voltage switching to fill the entire dead time range, has a value set by the resistor-capacitor delay circuit. <IMAGE></p> |
