Abstract: A method is shown to improve any forward topology operation to achieve efficient resonant transitions by actively shorting the magnetizing inductance and release the short at another time thus producing lower switching losses independent of frequency. In another embodiment of this invention the current from the output inductor is allowed to go negative before the freewheeling synchronous rectifier is turned off, pushing the current back into the primary to create a soft transition across the switching elements before they are turned on. In another embodiment of the invention a current source is used to inject a negative current through the freewheeling synchronous rectifier before is turned off with the purpose of transferring the current into the primary to discharge the parasitic capacitances of the primary switchers before are turned on. An optimized control method can be utilized to tailor the frequency to create the necessary conditions requested by the embodiments of the invention.

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.

Abstract: Meeting todays requirement in power supply technology demands significant technological advancement in optimizing circuit topology, components and materials, thermal and packaging designs. These requirements are being pushed mainly by continuously increasing power density and efficiency requirements. Ultimately, these trends will come to a point whereby limitations from the above mentioned technological advancements is dependent on one of the above, which is the packaging design. To realize this dependence, we need to look at the growing power systems for modern equipment out there. Let us enumerate some of the available AC adapters in terms of power densities of a 45 W adapter. Firstly, square type architecture introduced by Apple is about 7 W/in3, considering the packaging has a profile limitation whereby its AC plug is removable thus occupying relatively bigger chunk of the volume.

Abstract: A method is shown to improve the resonant transition controlled flyback converter presented in Ser. No. 14/274,598 (Exhibit A) by adding a clamp circuit that recycles the leakage energy. By utilizing the particular advantages of the resonant transition controlled flyback converter an optimized clamp capacitor can be used to increase the efficiency of the converter further.

Abstract: A method is shown to improve any forward topology operation to achieve efficient resonant transitions by actively shorting the magnetizing inductance and release the short at another time thus producing lower switching losses independent of frequency. In another embodiment of this invention the current from the output inductor is allowed to go negative before the freewheeling synchronous rectifier is turned off, pushing the current back into the primary to create a soft transition across the switching elements before they are turned on. In another embodiment of the invention a current source is used to inject a negative current through the freewheeling synchronous rectifier before is turned off with the purpose of transferring the current into the primary to discharge the parasitic capacitances of the primary switchers before are turned on. An optimized control method can be utilized to tailor the frequency to create the necessary conditions requested by the embodiments of the invention.