Abstract: Power systems including converters that exhibit reduced common mode voltage emissions are described. In one example, a power converter system includes an input and an output, a multi-level switch bridge coupled between the input and the output, an input capacitor branch coupled across the input, an output capacitor branch coupled across the output, and a controller configured to generate switching control signals for the multi-level buck-boost switch bridge. The multi-level switch bridge also includes a plurality of inductors in one example. In one case, a quadrangular or quadrangle control mode can be relied upon to switch the multi-level switch bridge, to minimize the ripple in the inductors, achieve zero voltage switching, reduce common mode electromagnetic interference emission by the converter, and for other benefits.

Abstract: A processor device has a CPU cooperating with an input device and an output device, under control of stored instructions, and is arranged to receive service requests at the input device, assign service requests received in successive time periods to respective batches of requests; access stored service provider data to identify available service providers from among a pool of service providers; after completing the assignment of service requests to a batch, perform a matching process to endeavour to match each service request of the batch of requests to a service provider; and for each service provider to whom a match is made, output a notification of the respective potential match from the output device.

Abstract: Power converters including electronic-embedded transformers for current sharing and load-independent voltage gain are described. In one example, a power converter system includes an input, an output, a power converter between the input and output, and a controller. The converter includes a first bridge, a second bridge, and an electronic-embedded transformer (EET) between the first and second bridge. The EET includes a capacitor and a capacitance coupling switch bridge. The controller generates switching control signals for the first and second bridges and phasing drive control signals for the capacitance coupling switch bridge in the EET. The controller applies a phase shift to the phasing drive control signals for the EET as compared to the switching control signals for the first and second bridges, so that the voltage across the capacitor in the EET cancels the leakage inductance of the transformer windings in the EET, at any switching frequency.

Abstract: Various examples of a high frequency, inductor and transformer core loss characterization and measurement method and system for arbitrary waveforms are disclosed herein. A system and method for determining core loss of a magnetic core can include generating a waveform to excite a first test circuit which comprises an excitation circuit, a circuit under test (CUT) comprising the magnetic core, and an inductance circuit having an inductor connected in parallel to the CUT. The method includes measuring a first current, when the first test circuit is excited. The method includes disconnecting the CUT from the first test circuit to form a second test circuit. The method includes generating the waveform to excite the second test circuit, and measuring a second current, when the second test circuit is excited. The power loss for the magnetic core is calculated based on an input voltage and the first and second measured current.

Abstract: Aspects of bidirectional architectures with partial energy processing in resonant direct current (DC)-to-DC converters are described. In one embodiment, an alternating circuit (AC)-to-DC circuit generates an AC voltage from a DC voltage. A voltage of the AC voltage is transformed into a majority AC voltage of a majority power path and at least one minority AC voltage of the minority power paths. The majority AC voltage is rectified into a majority DC voltage and a minority AC voltage is rectified into a minority DC voltage. The majority power path and the minority power path are combined as a combined DC voltage.

Abstract: Aspects of bidirectional architectures with partial energy processing in resonant direct current (DC)-to-DC converters are described. In one embodiment, an alternating circuit (AC)-to-DC circuit generates an AC voltage from a DC voltage. A voltage of the AC voltage is transformed into a majority AC voltage of a majority power path and at least one minority AC voltage of the minority power paths. The majority AC voltage is rectified into a majority DC voltage and a minority AC voltage is rectified into a minority DC voltage. The majority power path and the minority power path are combined as a combined DC voltage.

Abstract: Various examples of a high frequency, inductor and transformer core loss characterization and measurement method and system for arbitrary waveforms are disclosed herein. A system and method for determining core loss of a magnetic core can include generating a waveform to excite a first test circuit which comprises an excitation circuit, a circuit under test (CUT) comprising the magnetic core, and an inductance circuit having an inductor connected in parallel to the CUT. The method includes measuring a first current, when the first test circuit is excited. The method includes disconnecting the CUT from the first test circuit to form a second test circuit. The method includes generating the waveform to excite the second test circuit, and measuring a second current, when the second test circuit is excited. The power loss for the magnetic core is calculated based on an input voltage and the first and second measured current.

Abstract: Composite materials containing sulfurized polymers and sulfur-containing particles can be used in lithium-sulfur energy storage devices as a positive electrode. The composite material exhibits relatively high capacity retention and high charge/discharge cycle stability. In one particular instance, the composite comprises a sulfurized polymer having chains that are cross-linked through sulfur bonds. The polymer provides a matrix in which sulfide and/or polysulfide intermediates formed during electrochemical charge-discharge processes of sulfur can be confined through chemical bonds and not mere physical confinement or sorption.

Abstract: A crystalline nanowire and method of making a crystalline nanowire are disclosed. The method includes dissolving a first nitrate salt and a second nitrate salt in an acrylic acid aqueous solution. An initiator is added to the solution, which is then heated to form polyacrylatyes. The polyacrylates are dried and calcined. The nanowires show high reversible capacity, enhanced cycleability, and promising rate capability for a battery or capacitor.

Abstract: A method of preparing a graphene-sulfur nanocomposite for a cathode in a rechargeable lithium-sulfur battery comprising thermally expanding graphite oxide to yield graphene layers, mixing the graphene layers with a first solution comprising sulfur and carbon disulfide, evaporating the carbon disulfide to yield a solid nanocomposite, and grinding the solid nanocomposite to yield the graphene-sulfur nanocomposite. Rechargeable-lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter of less than 50 nm.

Abstract: Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm.

Abstract: Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm.

Abstract: Particular functional nanocomposite materials can be employed as electrodes and/or as electrodes in energy storage systems to improve performance. In one example, the nanocomposite material is characterized by nanoparticles having a high-capacity active material, a core particle having a comminution material, and a thin electronically conductive coating having an electronically conductive material. The nanoparticles are fixed between the core particle and the conductive coating. The comminution material has a Mohs hardness that is greater than that of the active material. The core particle has a diameter less than 5000 nm and the nanoparticles have diameters less than 500 nm.

Abstract: Composite materials containing sulfurized polymers and sulfur-containing particles can be used in lithium-sulfur energy storage devices as a positive electrode. The composite material exhibits relatively high capacity retention and high charge/discharge cycle stability. In one particular instance, the composite comprises a sulfurized polymer having chains that are cross-linked through sulfur bonds. The polymer provides a matrix in which sulfide and/or polysulfide intermediates formed during electrochemical charge-discharge processes of sulfur can be confined through chemical bonds and not mere physical confinement or sorption.

Abstract: A crystalline nanowire and method of making a crystalline nanowire are disclosed. The method includes dissolving a first nitrate salt and a second nitrate salt in an acrylic acid aqueous solution. An initiator is added to the solution, which is then heated to form polyacrylatyes. The polyacrylates are dried and calcined. The nanowires show high reversible capacity, enhanced cycleability, and promising rate capability for a battery or capacitor.

Abstract: Rechargeable lithium-sulfur batteries having a cathode that includes a graphene-sulfur nanocomposite can exhibit improved characteristics. The graphene-sulfur nanocomposite can be characterized by graphene sheets with particles of sulfur adsorbed to the graphene sheets. The sulfur particles have an average diameter less than 50 nm.