| 摘要 |
PROBLEM TO BE SOLVED: To improve power conversion efficiency and to simplify the circuit by eliminating a current limiter resistor of a large capacity and a low resistance, at an AC input line or an efficiency improvement by forming a circuit for short-circuiting the resistor of an electromagnetic relay or a thyristor triac or the like. SOLUTION: A magnetically coupled transformer MCT is provided as a power factor improving circuit 10 of a composite resonant converter. The primary side switching output is power fed back to a rectified current path by the transformer MCT, to interrupt the rectified current by a fast recovering diode D1 to improve the power factor. Furthermore, a soft switching circuit 13 formed by using a transistor is provided at the front stage of the circuit 10, so as to limit a rush current to a filter circuit Ci, when the power supply is turned on.
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