SWITCHING POWER SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce power loss while suppressing surge voltage.SOLUTION: A switching power supply 1 includes: a full-bridge circuit 10; a control circuit 20 which drives the full-bridge circuit by a phase control system; an isolation transformer 30 which includes a first coil 31 connected to the full-bridge circuit 10 and a second coil 32 magnetically coupled with the first coil 31; a rectifier circuit 40 connected to the second coil 32; a first reactor 50 which has a first end connected to the positive side output end of the rectifier circuit 40; a first capacitor 60 connected between a second end of the first reactor 50 and the negative output end of the rectifier circuit 40; and a snubber circuit 70 connected in parallel with the first reactor 50. The snubber circuit 70 includes: a first diode 71 which has an anode connected to the first end of the first reactor 50; and a CR circuit (72, 73) connected between the cathode of the first diode 71 and a second end of the first reactor 50. The first diode 71 is a step recovery diode.SELECTED DRAWING: Figure 1