Title:
SWITCHING POWER SUPPLY EQUIPMENT WITH SNUBBER CIRCUIT OF SMALL LOSS
Document Type and Number:
Japanese Patent JP3728575
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To make it possible to reduce surge voltage and noise without power loss by making the polarities of the capacitor-side terminals of a primary winding of a transformer and a reset winding agree with each other and allowing a diode to conduct when the flyback voltage of the reset winding becomes higher than the input voltage.
SOLUTION: When a switching device 4 is turned on, the voltage induced in a reset winding 1C becomes equal to the input voltage and the voltage at the switching device 4 side terminal of a capacitor 3 becomes nearly zero and the voltage at the opposite terminal becomes equal to the negative input voltage. When the switching device 4 is turned off, the voltage at the switching device side terminal of the capacitor 3 becomes the sum of the input voltage and flyback voltage and the voltage at the opposite terminal becomes equal to the flyback voltage and the voltage across the capacitor 3 becomes equal to the input voltage. The gradient of the fall current of a primary winding 1A at the time of turn-off of the switching device 4 is determined by the capacitance and the leakage inductance of the capacitor 3. Therefore, the bigger capacitance the capacitor has, the gentler the gradient becomes and thereby noise can be reduced.
Inventors:
Morio Sato
Application Number:
JP30141697A
Publication Date:
December 21, 2005
Filing Date:
September 25, 1997
Export Citation:
Assignee:
Ohira Electronics Co., Ltd.
International Classes:
H02M3/28; H02M1/00; (IPC1-7): H02M3/28; H02M1/00
Domestic Patent References:
| JP61157264A | ||||
| JP8251917A | ||||
| JP6296366A |