Abstract: A full bridge switching power supply is coupled to an ozonator load via a series resonant circuit having a resonant frequency above the switching frequency. Power output is controlled by varying the duration of the times when diagonal switches are conducting, and the output voltage has a longer rise time than fall time due to there being intervals between the conduction periods of diagonal switches during which one of the switches is turned on to permit resonant current flow. The driving voltages for attaining this action are symmetrical rectangular waves of identical shape having different phases that are derived from out of phase pulses where width is varied by the timing of their trailing edges.

Abstract: An ozonator power supply including a step-up transformer having one end of its primary winding connected to one side of an AC supply, its other end connected to the other side of the AC supply via a pair of switches connected in antiparallel, and a controller for providing switching pulses to said switches for making them conductive during variable portions of alternate half cycles of the AC voltage provided by said supply. An inductor is included in the circuit with the primary or secondary winding of the transformer that resonates with the capacitive impedance of an ozonator, for presenting a substantially non-reactive load to said AC supply.