Converters

Abstract

A high frequency converter of push-pull form comprises a center tapped D.C. input supply 16, 17, 18, two solid state switching devices (20, 21) connected in series across the D.C. input terminals, a load circuit including a supersonic frequency transformer 30 and an output rectifier 35, and an oscillatory circuit including at least one capacitor 40 and a parallel inductor 34 connected in parallel with the primary winding 37 of the transformer between the center tapping 19 of the supply and the junction 25 of the switching devices. The switching devices are synchronized to the oscillation of the oscillatory circuit to allow the circuit to oscillate freely for part of a cycle to transfer energy from the inductor 34 to the capacitor 40 to charge the latter to a certain condition in which the voltage across the parallel inductor is substantial and that across the switching device is negligible and only then connect the parallel inductor across the D.C. input terminals whereupon the parallel inductor receives and stores energy from the said supply. Means such as a saturable reactor 33 are connected in series in the load circuit to restrict load current to a low value during a part of the cycle in which the capacitor receives energy from the parallel inductor and until the capacitor is charged to the said condition and the switching means has connected the load circuit across the supply.