| 摘要 |
PROBLEM TO BE SOLVED: To provide an insulated DC-DC converter that does not need to use a switching element of large voltage resistance as an auxiliary switch constituting an active clamp circuit by preventing a transformer from reaching magnetic saturation even if the DC-DC converter is restarted by soft start. SOLUTION: The insulated DC-DC converter includes an active clamp circuit where a serial circuit of an auxiliary switch Q2 and a clamp capacitor 13 is connected with a primary coil 11 of a transformer 10. When operated, the main switch Q1 and the auxiliary switch Q2 are alternately controlled ON and OFF. A controller 20 controls the main switch Q1 and the auxiliary switch Q2 to repeat ON/OFF of the auxiliary switch Q2 until the voltage of a clamp capacitor 13 becomes less than the voltage to cause the magnetic saturation of the transformer 10 at the time of restart by soft start in the condition with the main switch Q1 kept OFF between the stop time and the restart time of the DC-DC converter. COPYRIGHT: (C)2011,JPO&INPIT
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