Abstract: A planar multilayer transformer in a power converter wherein winding arrangements and placement of shields reduces common mode noise to a level wherein the common mode inductor in an input EMI filter can be reduced and even eliminated decreasing the power dissipation and increasing the power density. The methods presented herein can reduce the number of layers in the multilayer PCB by eliminating the layers used for the shields and still be in full compliance with EMI requirements.

Abstract: This specification presents a boost topology operating in discontinuous mode wherein the energy contained in the parasitic oscillations is harvested and used to obtain zero voltage switching in any operating conditions. This boost topology is further used in power factor correction application wherein the operation frequency can be maintained in a very narrow range of operation.

Abstract: A system for reducing common-mode noise includes a switch mode power supply having primary and secondary sides, primary and secondary side grounds, an input voltage source, a primary switch, a transformer, a core, and a power output. The primary and secondary sides each have a quiet termination. The transformer includes a primary winding, a secondary winding, and an active shield winding between the primary and secondary windings. The active shield winding has two terminations, is wound in a same direction as the secondary winding, and occupies a same axial position on the core as the secondary winding. One of the terminations of the active shield winding is connected to the quiet termination of the primary side, so that the terminations of the secondary winding and the active shield winding that are adjacent each other carry alternating voltages of a same polarity and a same amplitude.

Abstract: A half bridge switching cell includes two primary switching elements connected in totem pole, across an input voltage source, wherein a connection common to the primary switching elements is defined as a primary switching node. A transformer has a primary winding in series with a capacitor, connected between the primary switching node and the input voltage source, and two secondary windings, each having first and second ends. The cell includes two synchronized rectifiers, each corresponding to a respective one of the primary switching elements, such that each of the synchronized rectifiers conducts when the respective one of the corresponding primary switching elements is not conducting. The first end of each secondary winding is connected to the drain of a respective one of the two synchronous rectifiers, and the second ends of the secondary windings are connected to a common connection and to at least one controlled current source.

Abstract: Electronic circuitry and a method of operating the same to obtain zero voltage switching on both primary switches in a flyback derived single ended asymmetrical half bridge topology, in all the operating conditions, both in continuous and discontinuous mode operation. Zero voltage switching is accomplished through voltage injection and through a combination of the voltage injection and current injection.

Abstract: In an embodiment, the specification describes power converters using soft switching in phase shifted full bridge topology wherein a current injection method is used to obtain zero voltage switching on all the primary switchers in all the operating conditions, wherein the amplitude of current injection is substantially decreased by creating a very good coupling between the primary of the transformer and the current injection winding, while creating a leakage inductance in between the secondary winding and said primary winding the current injection winding. The current injection is activated when the energy contained in the leakage inductance between primary and secondary is not enough to create zero voltage switching conditions for the switching elements. Once activated, the current injection flows preferentially towards the primary winding, discharging the parasitic capacitance reflected across primary switching elements of the resonant leg.

Abstract: A two-transistor forward switching cell includes two primary switching elements connected between an input voltage source and a primary winding of a transformer. The switching elements are connected to the primary winding at opposite ends of the winding. Reset diodes are connected between one of the opposite ends of the primary winding and one termination of the voltage source, and between another of the opposite ends of the primary winding and another termination of the voltage source. The transformer has at least a secondary winding connected to drains of synchronous rectifiers. One of the rectifiers is on during at least a portion of a time when the switching elements are on. The other of the rectifiers is a freewheeling rectifier, is connected to at least one controlled current source, and is off when the switching elements are on. Both rectifiers are on for a common predetermined time.

Abstract: A switching power conversion apparatus for converting power from an input voltage source to a load includes first and second switches connected to a switching node. An inductive element has a magnetizing current connected to the node, and the inductive element is connected to deliver energy via the first and second switches from the input voltage to the load during a succession of power conversion cycles. A capacitance connected to the node resonates with the inductive element to cause parasitic oscillation. A clamp subcircuit across the inductive element contains an auxiliary switch to trap energy and prevent parasitic oscillation, wherein the auxiliary switch is complementary to the first switch. A controlled voltage source injects energy in the inductive element, when the auxiliary switch turns off to discharge the parasitic capacitance by using trapped energy in the inductive element in addition to injected energy from the controlled voltage source.

Abstract: A magnetic structure in a power converter includes at least two multilayer boards, such as a primary board containing the primary windings and some auxiliary windings, and a secondary board containing the secondary windings and some auxiliary windings. The primary and secondary boards are on top of each other. On the layer on the primary board adjacent to the secondary board, is a dual function shield to reduce the total common mode noise in the converter towards zero. The controlled dual function shield can be placed on the secondary board on the layer adjacent to the primary board, and in some embodiments can be placed on both primary and secondary board on the layers adjacent to the other board. The embodiments herein offer a very good solution for cost reduction of the planar transformers and offers an avenue for total elimination of the common mode noise in a power converter.

Abstract: A method of optimizing the efficiency of an AC-DC converter, wherein the energy extraction time from the AC line is increased and as result the size of the bulk capacitor can be decreased and in applications wherein the size of the bulk capacitor is maintained constant the ripple across the bulk capacitor is decreased. The methods presented also increase the power factor in AC-DC converters. Extending the energy extraction from the AC line also lowers the RMS current through the input bridge and the input bulk capacitor. The reduction of the ripple across the bulk capacitor also increases the efficiency of the DC-DC converter, increasing in this way the overall efficiency of the AC-DC converter.

Abstract: A method of optimizing the efficiency of an AC-DC converter, wherein the energy extraction time from the AC line is increased and as result the size of the bulk capacitor can be decreased and in applications wherein the size of the bulk capacitor is maintained constant the ripple across the bulk capacitor is decreased. The methods presented also increase the power factor in AC-DC converters. Extending the energy extraction from the AC line also lowers the RMS current through the input bridge and the input bulk capacitor. The reduction of the ripple across the bulk capacitor also increases the efficiency of the DC-DC converter, increasing in this way the overall efficiency of the AC-DC converter.

Abstract: A magnetic assembly formed by a custom magnetic core and its bobbin with interconnection pins is presented. This magnetic assembly leads to a higher power density of magnetic assembly and a better utilization of the volume inside a power converter, allowing a higher power density of the power converter and a higher efficiency through the minimization of the parasitic inductances.

Abstract: A switching power conversion apparatus for converting power from an input voltage source to a load includes first and second switches connected to a switching node. An inductive element has a magnetizing current connected to the node, and the inductive element is connected to deliver energy via the first and second switches from the input voltage to the load during a succession of power conversion cycles. A capacitance connected to the node resonates with the inductive element to cause parasitic oscillation. A clamp subcircuit across the inductive element contains an auxiliary switch to trap energy and prevent parasitic oscillation, wherein the auxiliary switch is complementary to the first switch. A controlled voltage source injects energy in the inductive element, when the auxiliary switch turns off to discharge the parasitic capacitance by using trapped energy in the inductive element in addition to injected energy from the controlled voltage source.

Abstract: A magnetic structure in a power converter includes at least two multilayer boards, such as a primary board containing the primary windings and some auxiliary windings, and a secondary board containing the secondary windings and some auxiliary windings. The primary and secondary boards are on top of each other. On the layer on the primary board adjacent to the secondary board, is a dual function shield to reduce the total common mode noise in the converter towards zero. The controlled dual function shield can be placed on the secondary board on the layer adjacent to the primary board, and in some embodiments can be placed on both primary and secondary board on the layers adjacent to the other board. The embodiments herein offer a very good solution for cost reduction of the planar transformers and offers an avenue for total elimination of the common mode noise in a power converter.

Abstract: A switching power conversion apparatus includes an input voltage source, an output load, a first switch connected to a switching node, and a second switch connected to the switching node. An inductive element has a magnetizing current connected to the switching node. The inductive element delivers energy via the first and second switches from the voltage source to the load during power conversion cycles. A capacitance connected to the switching node can resonate with the inductive element during a portion of the power conversion cycles to cause a parasitic oscillation. A first clamp subcircuit is across the inductive element and contains a unidirectional auxiliary switch to trap energy from the inductive element and store it into the storage capacitor and prevent parasitic oscillation. The auxiliary switch is complementary to the first switch. A current source discharges the storage capacitor and uses the energy in the switching power conversion apparatus.

Abstract: A switching power conversion apparatus for converting power from an input voltage source to a load includes first and second switches connected to a switching node. An inductive element has a magnetizing current connected to the node, and the inductive element is connected to deliver energy via the first and second switches from the input voltage to the load during a succession of power conversion cycles. A capacitance connected to the node resonates with the inductive element to cause parasitic oscillation. A clamp subcircuit across the inductive element contains an auxiliary switch to trap energy and prevent parasitic oscillation, wherein the auxiliary switch is complementary to the first switch. A controlled voltage source injects energy in the inductive element, when the auxiliary switch turns off to discharge the parasitic capacitance by using trapped energy in the inductive element in addition to injected energy from the controlled voltage source.

Abstract: A magnetic and electrical circuit element including magnetic-flux-conducting posts, and a multi-layer structure formed with an electrically-conductive material. The multi-layer structure includes multiple layers forming a stack of layers along a length of the posts, said multi-layer structure configured as primary and secondary windings of a transformer. The primary winding is embedded in the multi-layer structure and wound around the magnetic-flux-conducting posts in such a way that a magnetic field induced in each of the magnetic-flux-conducting posts has a magnetic field polarity opposite to a polarity of the respective magnetic field of the magnetic-flux-conducting post adjacent the respective magnetic-flux-conducting post. Around each of the magnetic-flux-conducting posts, there is a respective one of the secondary windings connected to a semiconductor device.

Abstract: A two-transistor forward switching cell includes two primary switching elements connected between an input voltage source and a primary winding of a transformer. The switching elements are connected to the primary winding at opposite ends of the winding. Reset diodes are connected between one of the opposite ends of the primary winding and one termination of the voltage source, and between another of the opposite ends of the primary winding and another termination of the voltage source. The transformer has at least a secondary winding connected to drains of synchronous rectifiers. One of the rectifiers is on during at least a portion of a time when the switching elements are on. The other of the rectifiers is a freewheeling rectifier, is connected to at least one controlled current source, and is off when the switching elements are on. Both rectifiers are on for a common predetermined time.

Abstract: This specification discusses the concept of energy injection in a resonant circuit with initial conditions which is part of almost all of the present topologies. It presents in detail several methods of energy injection in a resonant circuit with initial conditions and how it applies to different topologies. It patent presents also a simple and economical method of driving the clamp switch in a flyback topology operating in discontinuous mode and a bias circuit in a flyback topology wherein the output voltage varies over a large range.

Abstract: A magnetic assembly formed by a custom magnetic core and its bobbin with interconnection pins is presented. This magnetic assembly leads to a higher power density of magnetic assembly and a better utilization of the volume inside a power converter, allowing a higher power density of the power converter and a higher efficiency through the minimization of the parasitic inductances.