PURPOSE: To maintain the output voltage of a current transformer constant, regardless of the magnitude of input voltage, and to maintain the operating point of an overcurrent protective circuit constant thus stabilizing the operation thereof by detecting a load current through a single current transformer having a primary winding provided with a center tap.
CONSTITUTION: In an overcurrent protective circuit 27, current flowing through the secondary winding of a power conversion transformer 5 is detected through the secondary winding 16 of a current transformer 13, and thus detected current is converted through a resistor 17 connected in parallel with the secondary winding 16 into a voltage, which is then rectified and applied on the base of a transistor 26. When the output on the secondary of the power converter 5 is higher, the transistor 26 in the overcurrent protective circuit 27 is turned ON and a conduction angle controlling transistor 14 is operated to control reset currents for saturable reactors 6a, 6b thus obtaining a drooping characteristic. In other words, the push-pull converter is constituted to detect current through a single current transformer 13 having primary winding 28 provided with a center tap 28.
MAMIZU TOSHIYUKI
MEGURO TAKESHI
