Abstract: According to an aspect of this disclosure, a circuit includes a voltage source and an output load, first and second resonant modules disposed between the voltage source and the output load, and first and second transformers. The circuit is further arranged such that the first transformer is disposed between the first resonant module and the output load, and the second transformer is disposed between the second resonant module and the output load. The circuit also includes a plurality of half-bridges coupled between the first and second resonant modules and the voltage source. The circuit further includes a voltage divider disposed between the voltage source and the plurality of half-bridges.

Abstract: A converter system includes a DC bus for each phase of an input AC power signal; a first switching cell for each phase, including first two active switches coupled in series across the DC bus and forming a first switching cell AC pole therebetween, the first switching cell AC pole being coupled to a respective phase; and a second switching cell for each phase, including second two active switches coupled in series across the DC bus and forming a second switching cell AC pole therebetween. The second switching cell AC poles are coupled to each other to form a flying neutral. One of the first switching cell and the second switching cell switches at a frequency at least an order of magnitude greater than the line frequency. The other of the first switching cell and the second switching cell switches at a frequency approximately equal to the line frequency.

Abstract: Unique systems, methods, techniques and apparatuses of photovoltaic (PV) string power systems are disclosed. One exemplary embodiment is a PV power system comprising a plurality of PV strings and a floating DC-DC optimizer. The floating DC-DC optimizer comprises a first DC bus rail, a second DC bus rail, a plurality of input legs, each leg being coupled across the first DC bus rail and second DC bus rail, including two input leg semiconductor switches coupled at an input terminal, each input terminal being structured to receive an input current from an end of one PV string of the plurality of PV strings, and an output leg including two output leg semiconductor devices coupled at an output terminal.

Abstract: According to an aspect of this disclosure, a circuit includes a voltage source and an output load, first and second resonant modules disposed between the voltage source and the output load, and first and second transformers. The circuit is further arranged such that the first transformer is disposed between the first resonant module and the output load, and the second transformer is disposed between the second resonant module and the output load. The circuit also includes a plurality of half-bridges coupled between the first and second resonant modules and the voltage source. The circuit further includes a voltage divider disposed between the voltage source and the plurality of half-bridges.

Abstract: According to an aspect of this disclosure, a circuit includes a voltage source and an output load, first and second resonant modules disposed between the voltage source and the output load, and first and second transformers. The circuit is further arranged such that the first transformer is disposed between the first resonant module and the output load, and the second transformer is disposed between the second resonant module and the output load. The circuit also includes a plurality of half-bridges coupled between the first and second resonant modules and the voltage source. The circuit further includes a voltage divider disposed between the voltage source and the plurality of half-bridges.

Abstract: In at least one illustrative embodiment, a three-stage power converter comprises a rectifier having an input to receive three-phase alternating-current (AC) and an output coupled to a first direct-current (DC) bus, a buck converter having an input coupled to the first DC bus and an output coupled to a second DC bus, and an LLC resonant converter having an input coupled to the second DC bus and an output to provide a DC charging current to a battery. The buck converter may be operable across a range of duty cycles to adjust a voltage level supplied to the second DC bus, and the LLC resonant converter may be operable in a plurality of modes to provide a plurality of discrete gain levels.

Abstract: In at least one illustrative embodiment, a three-stage power converter includes a rectifier having an input to receive three-phase alternating-current (AC) and an output coupled to a first direct-current (DC) bus, a buck converter having an input coupled to the first DC bus and an output coupled to a second DC bus, and an LLC resonant converter having an input coupled to the second DC bus and an output to provide a DC charging current to a battery. The buck converter may be operable across a range of duty cycles to adjust a voltage level supplied to the second DC bus, and the LLC resonant converter may be operable in a plurality of modes to provide a plurality of discrete gain levels.

Abstract: Unique systems, methods, techniques and apparatuses of an exemplary power converter are disclosed. One exemplary embodiment is a power converter comprising a power cell and a transformer. The power cell including a first and second DC input terminal, a first leg including a first and second switching device coupled and a first AC output terminal, a second leg including a third and fourth switching device and a second AC output terminal. The first and second AC output terminals are coupled to the AC power source and structured to receive an AC power from the AC power source. The transformer includes a primary winding, the primary winding being coupled across the first AC output terminal and the second AC output terminal.

Abstract: A converter system includes a DC bus for each phase of an input AC power signal; a first switching cell for each phase, including first two active switches coupled in series across the DC bus and forming a first switching cell AC pole therebetween, the first switching cell AC pole being coupled to a respective phase; and a second switching cell for each phase, including second two active switches coupled in series across the DC bus and forming a second switching cell AC pole therebetween. The second switching cell AC poles are coupled to each other to form a flying neutral. One of the first switching cell and the second switching cell switches at a frequency at least an order of magnitude greater than the line frequency. The other of the first switching cell and the second switching cell switches at a frequency approximately equal to the line frequency.

Abstract: Unique systems, methods, techniques and apparatuses of photovoltaic (PV) string power systems are disclosed. One exemplary embodiment is a PV power system comprising a plurality of PV strings and a floating DC-DC optimizer. The floating DC-DC optimizer comprises a first DC bus rail, a second DC bus rail, a plurality of input legs, each leg being coupled across the first DC bus rail and second DC bus rail, including two input leg semiconductor switches coupled at an input terminal, each input terminal being structured to receive an input current from an end of one PV string of the plurality of PV strings, and an output leg including two output leg semiconductor devices coupled at an output terminal.

Abstract: Unique systems, methods, techniques and apparatuses of a modular power transformer are disclosed. One exemplary embodiment is a matrix power transformer including a plurality of block assemblies each including a plurality of transformer modules, each transformer module including a primary winding coupled to an input and a secondary winding coupled to an output, the inputs of each transformer module in one block assembly being coupled together and the outputs of each transformer block being coupled together. One of the secondary windings includes a plurality of taps structured to be selectively coupled to the output of the associated transformer module assembly or another secondary winding of the associated module assembly.

Abstract: Unique systems, methods, techniques and apparatuses of an exemplary power converter are disclosed. One exemplary embodiment is a power converter comprising a power cell and a transformer. The power cell including a first and second DC input terminal, a first leg including a first and second switching device coupled and a first AC output terminal, a second leg including a third and fourth switching device and a second AC output terminal. The first and second AC output terminals are coupled to the AC power source and structured to receive an AC power from the AC power source. The transformer includes a primary winding, the primary winding being coupled across the first AC output terminal and the second AC output terminal.

Abstract: Unique systems, methods, techniques and apparatuses of a modular power transformer are disclosed. One exemplary embodiment is a matrix power transformer including a plurality of block assemblies each including a plurality of transformer modules, each transformer module including a primary winding coupled to an input and a secondary winding coupled to an output, the inputs of each transformer module in one block assembly being coupled together and the outputs of each transformer block being coupled together. One of the secondary windings includes a plurality of taps structured to be selectively coupled to the output of the associated transformer module assembly or another secondary winding of the associated module assembly.

Abstract: Unique systems, methods, techniques and apparatuses of a gate drive system are disclosed. One exemplary embodiment is a drive circuit electrically coupled to a main switching device including a first inverter, a first inverter controller, an air core transformer, at least one rectifier, at least two smoothing capacitors, a current buffer stage, and a detection circuit. The first inverter controller is structured to operate the first inverter in a first mode and a second mode. The air core transformer is structured to receive the converted AC power from the first inverter. The detection circuit is structured to detect a first mode of the first inverter and a second mode of the first inverter, and operate the current buffer stage based on a detected first mode of the inverter and a detected second mode of the first inverter.

Abstract: Among other things, a distribution transformer and a technique for regulating voltage are provided for herein. The distribution transformer comprises at least three windings and at least two ferromagnetic cores. The distribution transformer may also comprise a power electronic AC-AC converter operable to maintain the input voltage and current of the distribution transformer substantially in phase and/or to reduce fluctuation in the output voltage of the distribution transformer in the event of an increase or decrease in the input voltage, for example.

Abstract: Unique systems, methods, techniques and apparatuses of a gate drive system are disclosed. One exemplary embodiment is a drive circuit electrically coupled to a main switching device comprising a first inverter, a first inverter controller, an air core transformer, at least one rectifier, at least two smoothing capacitors, a current buffer stage, and a detection circuit. The first inverter controller is structured to operate the first inverter in a first mode and a second mode. The air core transformer is structured to receive the converted AC power from the first inverter. The detection circuit is structured to detect a first mode of the first inverter and a second mode of the first inverter, and operate the current buffer stage based on a detected first mode of the inverter and a detected second mode of the first inverter.

Abstract: A DC connection system for renewable power generators includes a first monopole DC collection network, a second monopole DC collection network and a first bipole transmission system. The first monopole DC collection network aggregates positive-valued DC voltage outputs of a first cluster of renewable power generators onto a positive terminal of the first monopole DC collection network. The second monopole DC collection network aggregates negative-valued DC voltage outputs of a second cluster of renewable power generators onto a negative terminal of the second monopole DC collection network. The first bipole transmission system is coupled to the positive and negative terminals of the monopole DC collection networks, for transferring the aggregated power to a power grid substation.

Abstract: A hybrid transformer is provided that includes an electromagnetic transformer and an AC-AC converter with a DC bridge. The AC-AC converter is operable to keep the input voltage and current of the hybrid transformer substantially in phase and to reduce fluctuation in the output voltage of the hybrid transformer in the event of an increase or decrease in the input voltage.

Abstract: A converter system for coupling to an ac power source includes a rectifier and a bi-directional converter. The rectifier has a first set of terminals inductively coupled to an ac power source and a second set of terminals coupled in series with a series dc bus, and is operable to convert ac power at the first set of terminals to dc power at the second set of terminals. The bi-directional converter has a first set of terminals coupled to the ac power source and a second set of terminals coupled to a parallel bus, and is operable to transfer power from the ac source to the parallel bus in a first operating mode and transfer power from the parallel bus to the series dc bus via the rectifier in a second operating mode. A corresponding power generation network and power transmission method are also provided.

Abstract: Power conversion apparatus for controllably converting alternating current (AC) to direct current (DC). An example apparatus includes multiple AC sources, galvanically isolated from one another, and multiple bridge rectifier circuits, including one or more controllable bridge rectifier circuits, where each bridge rectifier circuit has respective AC-side terminals and DC-side terminals and each bridge rectifier circuit is connected to a corresponding one of the AC sources via its AC-side terminals. The DC-side terminals are connected so that the outputs of the bridge rectifier circuits are combined in series.