RESET CURRENT DRIVE CIRCUIT OF MAGNETIC AMPLIFIER AND SWITCHING POWER SUPPLY CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a small-size reset current drive circuit of a magnetic amplifier in the simplified structure which assures easier wiring layout on a printed circuit board and less amount of load of an auxiliary power supply. ;SOLUTION: This reset current drive circuit comprises a circuit 240 for controlling a reset current flowing through a saturable reactor 201 based on a DC voltage value from a rectified output circuit, and an over-current protection circuit 250 for applying the reset current to the saturable reactor 201 to protect a core of the saturable reactor 201 from the saturation, when an output current of the rectified output circuit is in the over-current condition. The over- current protection circuit includes a current control element 252 connected between an output side terminal of the saturable reactor and the ground terminal, and an over-current detection circuit for detecting the over-current condition. When the over-current condition is detected, the current control element 252 is controlled with a control signal from the over-current detection circuit, and the rest current is applied to the saturable reactor 201 from the ground terminal side.;COPYRIGHT: (C)2003,JPO