| 摘要 |
PROBLEM TO BE SOLVED: To provide a soft switching flyback DC-DC converting circuit which materialized downsizing by reducing the conduction loss and enhancing the conversion efficiency. SOLUTION: A flyback transformer 20 is coupled closely with the circuit, and a reactor 50 for resonance is connected to the secondary low current side of the flyback transformer 20, whereby it becomes possible to enhance the conversion efficiency by reducing the conduction loss and core loss of the flyback transformer 20 and the reactor 50 for resonance. Consequently, it becomes easy to downsize the frame and secure the mounting space. Moreover, since the reactor 50 for resonance is a saturable reactor, it is possible to make the switching frequency constant without depending upon load condition by reducing the inductance value of the reactor 50 for resonance using a saturation region at high load, and increasing the switching frequency to the same level as that at the low load. Accordingly, it is possible to downsize the device easily by increasing the switching frequency.
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