Abstract: Electronic circuitry and method of operating the same to shape and reduce the circulating current through the active clamp in a flyback converter and to harvest most of the leakage inductance energy to provide the bias power. Methodologies for minimizing the circulating energy in the clamp circuit in order to improve efficiency of operation of the same. A method for using a portion of the leakage inductance energy in order to create zero voltage switching conditions at the main primary switch.

Abstract: A method is shown to create soft transition in selected topologies by controlling and designing a current pulse injection in front of the output choke to overwhelm the output current at a certain point in the switching cycle.

Abstract: In this invention we introduce the concept of a fundamental switching cell with complimentary switchers s and a controlled dead time which is one of the embodiments of this invention. This fundamental switching cell can be used in isolated DC-DC Converter applications and also used for totem pole bridgeless power factor correction applications. One of the main embodiments of this invention describes a circuit wherein such a fundamental switching cell is used to transfer the power across a transformer towards secondary while providing power factor correction for the input line current while extracting the energy from the line and steering the low frequency ripple of the input current towards the bulk capacitor and regulating the voltage in the secondary of the transformer.

Abstract: Ideal switch bridgeless PFC topologies are presented with the purpose of increasing the efficiency in power factor correction circuits and inverter applications. The topology also leverages the new GaN switches that are available. This patent offers also a very good solution for the Zero crossing distortion problem improving greatly the THD both in power factor correction and inverter applications.

Abstract: A method is shown to create soft transition in selected topologies by controlling and designing the magnetizing current in the main transformer to exceed the output current at a certain point in the switching cycle.

Abstract: A method for operation of a single-ended forward converter to achieve “true soft switching” The method includes injecting, with a current source and in transformer winding, a narrow pulse of current via an injection winding of the transformer to add such pulse to the magnetizing current to exceed the current level of current passing through freewheeling rectifier to reduce that current to zero time when the freewheeling rectifier is turns off at zero current conditions. Further, the sum of the magnetizing current and the injected current provide the current required by the output inductor during the transition time. The amplitude of injected current is defined such that the sum is greater than the minimum current through the output inductor (at least by an amount that reflects into the primary winding). The amount of current reflected in the primary is chosen to be sufficiently large to discharge parasitic capacitances reflected across the primary main switch to zero during the transition time.

Abstract: A method is shown to create soft transition in selected topologies by preserving the leakage inductance energy during the dead time and using several techniques to supplement the energy require to discharge the parasitic capacitance of the primary switchers and obtain zero voltage switching. One technique consists in a current pulse injection across the synchronous rectifiers during the dead time and prior the turn off of the synchronous rectifiers. A second technique consist in tailoring the magnetizing current through frequency modulation to increase the energy in the leakage inductance and use that energy to discharge the parasitic capacitance of the primary switchers and at lighter load to have a magnetizing current which exceeds the current through the output inductor at the end of the dead time. The third technique is interleaving two converters and sharing a couple inductance in a way to lower the current through each output inductor under the level of the magnetizing current at its lowest amplitude.