Abstract: A device to control the transfer of energy via resonant circuits from a D.C. source of electric energy to a load. The device confines the resonant currents to near the magnitude needed to accomplish this controlled transfer within prescribed limits, independent of variations of the source voltage or of the load. The voltage stresses imposed on the individual circuit components are contained accordingly. An electronic control system governs the electronic power switches to conform to a pattern of operation which confines the average currents in the resonant circuits to preset levels and therewith confines the series capacitor voltage amplitude to predictible and restricted magnitudes. The rms content of the resonant current is restricted to predictible and moderate deviations from a design norm for specified conditions of system operation.