| 摘要 |
PROBLEM TO BE SOLVED: To facilitate design and manufacture, and improve power conversion efficiency. SOLUTION: In a combined resonance type switching converter having a self-excited voltage resonance type converter as a basic structure; a detection winding NA, a driving winding NB of a self-excited oscillation driving circuit, and a control winding NC are wound around a driving transformer CDT. A circuit in which the control winding NC, a capacitor CB2, and a continuity control device Q2 are connected in series is provided on a secondary side. For stabilization, the current continuity amount of the continuity control device Q2 is changed to make changeable a base current level flowing through a base of a switching device Q1 from the self-excited oscillation driving circuit, thus variably controlling switching frequency. The voltage between the base and an emitter of the continuity control device Q2 is formed into a saw-toothed wave to decrease switching loss in the switching device Q1. A low-speed recovery type diode and a resistor are connected between the base and the emitter of the switching device, and the low-speed recovery type diode is connected with the capacitor in parallel. The continuity control device Q2 is connected with a high-speed recovery type diode in parallel.
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