Agence Spatiale Europeenne

Organisation Europeenne De Recherches Spatiales

Alan H Weinberg

Dermot M O'Sullivan

A switching current converter is connected in parallel with each controlled power switch in an electric circuit so that it is allowed to operate from the input voltage and transfer energy from input to output during the turn-on periods of the controlled power switch, whereby each power switch is allowed to be turned ON when a near-to-zero voltage is present across it. The switching converter serves as an active power switch stress relieving means, resulting in minimizing the switching loss in the power switch while providing the energy for operation of the power switch in a very efficient way.

Method for minimizing the switching loss in a power switch

A quasi-resonant DC to DC converter having zero-current and zero-voltage switching includes a transformer with primary and secondary windings, and periodic switching means connected in series with the primary winding. The converter further includes an input capacitor parallel to the transformer's primary winding and an output capacitor parallel to the secondary winding. The topology of the converter is determined by selecting an input capacitor having a capacitance much lower than the output capacitor, by selecting the resonance period of a circuit including the input capacitor and the overall series inductance of the transformer to be shorter than the ON period of the periodic switching means, and by selecting the resonance period of a circuit including the overall parasitic capacitance, referred to the primary side of the transformer and the periodic switching means, and the magnetizing inductance of the transformer to be shorter than the OFF period of the periodic switching means.

DC to DC converter using quasi-resonance

Two switching circuits are connected between the gate and the source electrode of a field effect transistor, each of said circuits comprising a controlled switch and a secondary winding of a pulse transformer. A first pulse generator produces at a predetermined rate a pulse having a first logic state for driving the controlled switch of a first of said switching circuits, said pulse being applied to a transformer primary winding, and a second pulse generator produces at a predetermined rate a pulse having a second logic state which is complementary to the logic state of the pulse produced by the first pulse generator, for driving the controlled switch of the second switching circuit, each primary winding being magnetically coupled with a secondary winding.

Drive circuit for a power field effect transistor

A current sensing regulator operates in a switching mode of regulation between two sensed current levels in a free-running operation, or between one of the current levels and an intermediate level in a fixed-frequency synchronization operation. The sensed current levels at which switching occurs are set through a command signal, and a comparator controls switching at the set current levels or at the occurrence of synchronization pulses.

Current sensing regulator

A low dissipation shunt or series regulator apparatus is described comprising dump switching means coupled in parallel to each power source, which dump switching means is arranged for being responsive to a control signal produced by comparator means arranged for comparing the level of the error signal with a respective reference level. Each power source has its output connected to the reference level input of the corresponding comparator through feedback circuit means in order to set two operation thresholds for the comparator, thereby allowing each dump switching means to switch cyclically between two states, a first state serving to short the corresponding power source and a second state serving to allow the power source to provide current to the load.

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Sassenheim, Netherlands

Alan H Weinberg