Abstract: A switching power supply includes an output transformer including a primary winding and a secondary winding. The primary winding is coupled to a switching transistor. Of importance, a diode is coupled across the switching transistor. During the time period before the switching transistor turns on, the output transformer draws magnetizing current through the diode, and thus before the transistor turns on, the voltage across the transistor is limited to one diode voltage drop. Thus, the switching losses incurred when the transistor turns on are minimized. In one embodiment, the power supply is a full bridge converter including first and second transistors coupled to one lead of the primary winding, and third and fourth transistors coupled to a second lead of the primary winding. The output voltage of the converter is regulated by regulator circuit which modulates the switching phase of the first and second transistors relative to the third and fourth transistors.

Abstract: A switching power supply includes an output transformer including a primary winding and a secondary winding. The primary winding is coupled to a switching transistor. Of importance, a diode is coupled across the switching transistor. During the time period before the switching transistor turns on, the output transformer draws magnetizing current through the diode, and thus before the transistor turns on, the voltage across the transistor is limited to one diode voltage drop. Thus, the switching losses incurred when the transistor turns on are minimized. In one embodiment, the power supply is a full bridge converter including first and second transistors coupled to one lead of the primary winding, and third and fourth transistors coupled to a second lead of the primary winding. The output voltage of the converter is regulated by modulating the switching phase of the first and second transistors relative to the third and fourth transistors.

Abstract: A transformer for use in a power converter includes first and second primary windings tightly coupled to a first secondary winding, and third and fourth primary windings tightly coupled to a second secondary winding. Of importance, the first and second primary windings are only loosely coupled to the third and fourth primary windings. In one embodiment of the invention, the transformer includes a plurality of legs. The first and second primary windings and the first secondry winding are wound around one half of one of the legs but not a secnd half of the one leg. The third and fourth primary windings and the second secondary winding are wound around the second half of the one leg but not the first half. In another embodiment of the invention, the transformer includes a U core. The first and second primary windings and the first secondary winding are wound around a first leg of the U core while the third and fourth primary windings and the second secondary winding are wound around a second leg of the U core.

Abstract: A control circuit is provided for controlling the on-time of a pair of switching transistors in a half bridge converter. The control circuit includes a first comparator for comparing the converter output voltage with a reference voltage. The control circuit also includes a circuit which generates a first signal indicative of the current through the primary winding of the converter output transformer. Also included is a circuit which generates a second signal indicative of the on-time of one of the switching transistors exceeding the on-time of the other switching transistor. The first and second signals are averaged and compared with the output voltage of the first comparator by a second comparator. The second comparator controls the on-time of the switching transistors. In this way, any imbalance in the on-time of the switching transistors is corrected by the control circuit.

Abstract: A power supply uses first and second saturable reactor means connected to receive complementary first and second input voltages. The first saturable reactor means is disconnected from the first input voltage when the second saturable reactor means is connected to the second input voltage and vice versa. The power supply includes structure for sensing a variation in the power supply output voltage from a desired value and for producing a control signal in response thereto. A signal representative of volt-seconds, generated in a feedback path, is passed through both first and second saturable reactor means to adjust the flux in the particular saturable reactor means not connected to its input signal. This sets the initial flux in that saturable reactor means the next time it is connected to its input voltage. A change in the power to be supplied by the power supply causes a change in the time necessary to saturate each of the two saturable reactors.

Abstract: A high current, low voltage, regulated D.C. power supply incorporating a parallel pair of bridges connected across a D.C. supply and each having alternately switched opposite legs for producing across its output a relatively high frequency A.C. to a stepdown transformer. Each of the bridges is switched out of phase with the other to minimize output ripple in the combined D.C. produced from rectifiers at the secondary of the stepdown transformers. Regulation of the supply is provided by a current sensor at the secondary of each transformer which produces a signal that is compared with a signal representing D.C. output level to alter the duty cycle in the switching circuitry to the parallel bridges. The novel feature is that the regulation control circuits of two or more identical supplies may be coupled to produce master-slave power supply combinations capable of greatly increasing the output power capabilities.