Abstract: The power converter of this invention accomplishes zero voltage switching at both turn on and turn off transitions of all primary switches. A pair of coupled inductors serve as both energy storage devices and isolation mechanisms. The placement of a small inductor in series with the coupled inductors enables the invariance of primary current direction throughout the switching transition which provides for zero voltage switching for all switches for all transitions. The power converter behaves as a pair of interleaved coupled inductor buck converters with oppositely directed magnetizing currents. During a first half cycle, while one inductor is coupled to the output, the other uncoupled inductor behaves as a current source, setting the primary winding currents for both inductors equal to the magnetizing current of the uncoupled inductor. The inductor which is coupled to the output appears as an output filter capacitor or voltage source to the uncoupled inductor during the first half cycle.

Abstract: A DC to DC converter circuit which accomplishes both non-pulsating input and output currents using a single simple coupled inductor is revealed. The DC to DC converter accomplishes either buck or boost conversion using a simple circuit requiring only two switches, one of which may be a simple diode rectifier, a capacitor, and two inductors, which may be colocated on a single common magnetic core. These converters are, in some ways, similar to the Cuk converter, but they do not provide inverted outputs. Zero voltage switching versions of these converters are revealed. Also revealed are techniques and methodology for reducing both input and output current ripple to near zero levels. The buck version of the circuit accomplishes DC to DC conversion without inversion and with no right half plane zero in its control to output transfer function. The boost version is also non-inverting.

Abstract: A generalized active reset switching network using a small choke, a pair of switches, and a capacitor is revealed. The application of the generalized active reset switching network to any of a wide variety of hard switching power converter topologies yields equivalent power converters with zero voltage switching properties, without the requirement that the magnetizing current in the main power choke be reversed during each switching cycle. In the subject invention the energy required to drive the critical zero voltage switching transition is provided by the small choke that forms part of the generalized active reset switching network. The application of the generalized active reset switching network to buck, boost, buck boost, Cuk, and SEPIC converters is shown. A variation of the generalized active reset switching network which adds a single diode to clamp ringing associated with the parasitic capacitance of off switches is also revealed.

Abstract: A DC transformer circuit which accomplishes zero voltage switching for all switches for all transitions is revealed. The DC transformer is also self clamping so that clamping can be accomplished without compromising tight magnetic coupling and without using valuable window area for a clamp winding. The wave forms generated at the secondary windings are suitable for synchronous rectifier self drive. The combination of lossless switching, tight coupling, synchronous rectifier self drive, and maximum window utilization results in a DC transformer circuit which is suitable for high frequency, high efficiency operation. The DC transformer circuit uses two independent transformers with primary windings activated in anti-synchronization. The primary windings of the transformers are driven by a half bridge, a full bridge, or a push pull switching network.

Abstract: The power converter of this invention accomplishes zero voltage switching at both turn on and turn off transitions of four primary switches (220, 224, 228, and 232). A pair of coupled inductors (242 and 244) serve as both energy storage devices and isolation mechanisms. The stored energy in the coupled inductors (242 and 244) is used to drive the resonant transitions. The availability of stored energy in a coupled inductor for driving a switching transition is dependent on the timing of secondary switches (250 and 252) whereby the turn off of the secondary switches is delayed until the transition of the primary switches is complete. The power converter behaves as a pair of interleaved coupled inductor buck converters with oppositely directed magnetizing currents. During a first half cycle, while one inductor is coupled to the output, the other uncoupled inductor behaves as a current source, setting the primary winding currents for both inductors equal to the magnetizing current of the uncoupled inductor.

Abstract: The magnetic circuit element structure of this invention comprises a minimum four layer stacked layer sandwich construction in which layers of printed wiring board are alternately interleaved with layers of magnetic core material. Pins or wires form a part of the structure and are provided to electrically connect printed wiring board layers to form winding turns. Specifically, the pins or wires connect the copper foil patterns on layer 1 to the copper foil patterns on layer 3. Legs made of a magnetic core material also form a part of the structure and are provided to magnetically connect the core layers 2 and 4 in order to provide a closed path for magnetic flux. In the minimal structure a first layer consisting of a printed wiring board contains half turns of copper foil in one or more printed wiring board layers. The second layer is formed of ferrite or some other ferromagnetic core material.

Abstract: The power converter of this invention accomplishes zero voltage switching at both turn on and turn off transitions of a primary switch (206). A transformer (218) serves as both energy storage device and isolation mechanism. Inductance (216) placed in series with transformer (218) provides energy to drive the turn on resonant switching transition of switch (206). Additional energy storage is provided by a required primary side filter capacitor (220) and an output filter capacitor (224). During a first operational state in which switch (206) conducts, energy is transferred from power source (202) to transformer (218) and capacitor (220). During the first state, capacitor (224) supports a load (226). During a second operational state, a second primary switch (212) and a secondary switch (234) conduct and energy is transferred from capacitor (220) and transformer (218) to series inductance (216), capacitor (224) and load (226).