Abstract: A novel resonant DC-to-DC converter has a source of direct current which is switched through a primary inductor, or the primary winding of a transformer in a primary circuit, to provide energy to an LC tank circuit. The sinusoidal, AC tank voltage is impressed upon an output winding that feeds an output smoothing inductor through a full wave rectifier. The resultant direct current output is made availabe to a load. A unidirectional switch operates in response to a switch control to perform the switching in the primary circuit at near zero current conditions. The switch control opens the unidirectional switch to end the current pulse. The length of the current pulse is proportional to the magnitude of the load.

Abstract: A resonant power converter is disclosed which is constructed on an integrated magnetic core, with primary, secondary and tertiary windings occupying separate legs of the core. The tertiary winding is connected in a resonant circuit and induces a flux in the primary leg that causes the primary winding current to assume the shape of a series of generally sinusoidal pulses. Primary winding switching can thus occur at zero primary current between pulses, thereby eliminating prior interference problems. Furthermore, the converter can be operated in a pulse width modulated mode to accommodate for varying output load levels without the problems of low frequency operation encountered by prior frequency modulated resonant converters.