An apparatus includes a DC-to-AC converter comprising a first output terminal and a second output terminal. The apparatus also includes a DC-to-DC converter comprising a third output. The DC-to-AC converter is configured to receive a DC input voltage from a DC power source, and to produce a first alternating output voltage at the first output terminal, and a second alternating output voltage at the second output terminal. The DC-to-DC converter is configured receive a DC input voltage from the DC power source, and to step down the DC input voltage at the third output.

One aspect of the disclosure includes a submodule topology for a modular multilevel converter. The submodule topology includes two electronic switches connected together with a first series connection terminal connecting the electronic switches in series, the series connected switches being connected in parallel with two capacitors connected together with a second series connection terminal connecting the capacitors in series. A bidirectional electronic switch connects the first series connection terminal with the second series connected terminal. An output voltage is obtained across the first series connected terminal and a common terminal formed by the parallel connection of the series connected switches with the series connected capacitors.

Apparatuses, systems, and methods for managing power utilizing synchronous common coupling. An apparatus comprises a synchronous common coupling, a plurality of ports, and a plurality of stacks connected through the synchronous common coupling. Each stack comprises at least one stage, with each stage comprising at least one source/load bridge, at least one flux bridge, and a DC bus. The at least one source/load bridge of one stage of each stack is connected to a source or load through one of the plurality of ports, the at least one flux bridge of each stage is connected to an electrically isolated winding in the synchronous common coupling, and the at least one flux bridge of each stage is connected to the at least one source/load bridge of the stage through the DC bus. The synchronous common coupling is configured to exchange power between each of the plurality of stacks.

A wind power generation system including a doubly fed induction generator (DFIG) of a wind turbine is presented. The DFIG includes a rotor and a stator, a rotor-side conversion unit coupled to the rotor, a direct current (DC) link, and at least one line-side conversion unit coupled to the rotor-side conversion unit via the DC link and coupled to the stator of the DFIG. The at least one line-side conversion unit includes exactly one first converter, high frequency transformers, and second converters, where each of the second converters is coupled to the first converter via a respective high frequency transformer, and inverters, where each of the inverters is coupled to a respective second converter and includes an alternative current (AC) phase terminal.

A power converter circuit includes a plurality of first converter cells, a plurality of second converter cells, and a plurality of DC link capacitors. Each of the plurality of first converter cells is coupled to a corresponding one of the plurality of DC link capacitors. Each of the plurality of second converter cells is coupled to a corresponding one of the plurality of DC link capacitors. At least one of the plurality of second converter cells is configured to, during start-up of the power converter, internally dissipate power received from the corresponding DC link capacitor while a cell output power of the at least one of the plurality of second converter cells is substantially zero.

A single-phase AC/DC electric power conversion apparatus includes an indirect matrix converter having an input interface to receive a first alternating current (AC) signal and an output interface to produce a second AC signal, where the first AC signal has a grid frequency. A transformer has a primary winding and an electrically isolated and magnetically coupled secondary winding. A coupling inductor is connected in series between the output interface of the indirect matrix converter and the primary winding. An H-bridge switching arrangement is connected to the secondary winding and produces an output signal having a DC component and at least one AC component. The at least one AC component has a second order harmonic of the grid frequency. An active filter reduces the second order harmonic AC component. A modular conversion apparatus for three-phase power replicates the single-phase apparatus as a module for each phase and omits the active filter.

In one embodiment, a power cell module includes: a high frequency line converter (HFLC) to receive a phase of input power from a utility source, the HFLC including a first silicon carbide (SiC) stage and a second SiC stage; a transformer having a primary coil coupled to the HFLC and a secondary coil coupled to a high frequency motor converter (HFMC); the HFMC to output a phase of output power to a load, the HFMC including a third SiC stage and a fourth SiC stage; and a two-phase cooling system having conduits that are adapted to provide a flow of cooling media through the HFLC, the transformer and the HFMC.

Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and/or phases, then the energy is transferred out of the inductor to one or more output portals and/or phases, with said parallel capacitor facilitating soft turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor/capacitor cycle, thereby maximizing inductor/capacitor utilization as well as providing for optimum converter operation with high input/output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

A single-phase AC/DC electric power conversion apparatus includes an indirect matrix converter having an input interface to receive a first alternating current (AC) signal and an output interface to produce a second AC signal, where the first AC signal has a grid frequency. A transformer has a primary winding and an electrically isolated and magnetically coupled secondary winding. A coupling inductor is connected in series between the output interface of the indirect matrix converter and the primary winding. An H-bridge switching arrangement is connected to the secondary winding and produces an output signal having a DC component and at least one AC component. The at least one AC component has a second order harmonic of the grid frequency. An active filter reduces the second order harmonic AC component. A modular conversion apparatus for three-phase power replicates the single-phase apparatus as a module for each phase and omits the active filter.

We disclose herein a power coupler for connecting AC or DC electrical circuits having different voltages, current or impedance levels. The power coupler comprise a first switching device; a second switching device coupled with the first switching device; a power transformer comprising a first core winding and a second core winding; a first capacitance coupled between the terminals of the first core winding; a second capacitance coupled between the terminals of the second core winding; and a third capacitance coupled between the first and second cores windings. The power transformer is coupled with the first and second switching devices. The power coupler is configured to reduce switching power loss using an adiabatic technique and by selecting appropriate switching time of the switching devices.