Pulse control drive system for power transistors

Claim 1

In a drive system for a power device supplying a load from a source of operating current the combination of: an oscillator circuit including a pair of devices, and transformer means operatively coupling said pair of devices in such a manner to alternatively drive one device into full conduction and the other out of conduction, each of said pair of devices connected in a Darlington circuit arrangement with said power device to supply continuous drive current thereto when respectively conductive, said power device comprises a power transistor including base, collector and emitter electrodes, said pair of devices comprises a pair of transistors each including base, collector and emitter electrodes, said emitter electrodes of said pair of transistors are commonly connected to the base electrode of said power transistor, said transformer means comprises a saturable transformer including a first and second winding, said first and second windings being so wound with respect to one another that when one of said pair of devices is rendered conductive a signal of such a polarity is provided to drive it quickly into full conduction, which is maintained until said saturable transformer saturates, thereby removing drive current from the conductive of said pair of devices and supplying drive current to the previous non-conductive of said pair of devices and driving it into full conduction in the same manner as the previously conductive of said pair of devices, said first winding is operatively connected between said collector electrodes of said pair of transistors so that base drive current is supplied through the collector-emitter circuit of the conductive one of said pair of transistors to the baseemitter circuit of said power transistor, and said second winding is operatively connected between said base electrodes of said pair of transistors for supplying base drive current respectively thereto, said first winding supplied with current from said source via said load, and said base drive current supplied to said power transistor being proportional to the load current, said first winding includes first and second winding sections, and said second winding includes first and second winding sections, said first winding sections of said first and second windings and said second sections of said first and second windings are respectively wound with respect to one another so that one of said pair of transistors is alternately driven into full conduction and the other out of conduction, said first winding is supplied with current from said source via said load at a point between said first and second winding sections thereof.