Abstract: Disclosed is a switching power supply which can realize the saving of space and low-cost manufacturing. On-off control of FET (3), intermittently applies D.C. input voltage V-IN to the primary windings (1A, 2A), of transformers (1,2). Current detection circuit (15) detects the voltage drop caused by the resistance of the secondary windings (1B,2B) to produce output current detection signals in proportion to the load current (1D). The resistance of the secondary windings (1B,2B) of transformers (1,2) can be employed as a current detector, whereby saving of space and low-cost manufacturing of power supplies can be realized.

Abstract: Disclosed is a power supply which can be optionally designed in accordance with the objects. Main parts constructing a power supply are divided into noise filter module 3, power factor and harmonic correction module 4, D.C./D.C.converter 5, back-up power supply module 7, and the like. Each module is optionally combined and connected to one another, thus a user can freely design a power supply depending upon the various specifications thereof.

Abstract: A boost converter having a plurality of boost converter units in parallel operation. Within each boost converter unit, current transformers 22,23 are connected in series respectively to switching element 7 and diode 8. The current transformers 22,23 permit detected current therefrom to output current detection signals from current detection circuits. Then, the current detection signals within one converter unit 3 will be compared with those within the other converter unit 3A in parallel operation by comparing circuit 33. On the basis of a result of such comparison, D.C. output voltage Vout can be controlled to be equal to each other in each converter unit 3,3A.

Abstract: A DC-DC convertor includes a transformer having a primary winding adapted to be connected in series with a DC power source and a secondary winding, a rectifier and smoothing circuit, a main switching device, adapted to be connected in series with the DC power source, for connecting the rectifier and smoothing circuit to the secondary winding of the transformer when the main switching device is in an on-state, an auxiliary switching circuit connected in parallel with the main switching device, and a signal generating circuit for providing a first control signal to the main switching device and a second control signal to the auxiliary switching circuit. The auxiliary switching circuit includes a first capacitor connected in parallel with a second capacitor that is connected in series with an auxiliary switching device.

Abstract: A DC-DC converter includes a transformer and a switching element. The primary winding of the transformer and the switching element are connecting in series with a DC power source. A DC output is extracted via a rectifier circuit connected to a secondary winding of the transformer. A capacitor is connected in parallel to the switching element, and a saturable reactor is connected between the secondary winding of the transformer and the rectifier.