| 摘要 |
PURPOSE:To reduce the power loss by providing an overcurrent detecting resistor at the secondary side of a current feeding back transformer, and controlling an overcurrent control transistor on the basis of the overcurrent. CONSTITUTION:The primary winding 18 of a current transformer 1 is connected in series with the collector of a switching transistor 3, and the secondary winding 19 of a current transformer 17 is connected between the base and the emitter of the transistor 3 through a reverse blocking rectifying diode 20. An overcurrent detecting resistor 22 is provided at the secondary side of the transformer 17, and an overcurrent control transistor 21 is controlled on the basis of the resistor 22. The base currents supplied from the secondary winding 19 of the transformer 17 and the tertiary winding 6 of the transformer 2 are branched to the transistor 21, thereby limiting the collector current of the transistor 3. |
