Abstract: A method for power conversion includes coupling a first string to a second string via a first connecting node and a second connecting node to form at least one leg of a power converter. The first string is operatively coupled across a first bus and a second bus and comprises a first branch and a second branch coupled via a third connecting node. The first branch and the second branch include a plurality of controllable semiconductor switches. Furthermore, the second string comprises a first chain link and a second chain link coupled via an alternating current phase bus and includes a plurality of switching units. The first chain link and/or the second chain link are controlled to generate a negative voltage across at least one of the plurality of controllable semiconductor switches during a switch turn off process.

Abstract: A method for power conversion includes coupling a first string to a second string via a first connecting node and a second connecting node to form at least one leg of a power converter. The first string is operatively coupled across a first bus and a second bus and comprises a first branch and a second branch coupled via a third connecting node. The first branch and the second branch include a plurality of controllable semiconductor switches. Furthermore, the second string comprises a first chain link and a second chain link coupled via an alternating current phase bus and includes a plurality of switching units. The first chain link and/or the second chain link are controlled to generate a negative voltage across at least one of the plurality of controllable semiconductor switches during a switch turn off process.

Abstract: A power converter including one or more converter legs is provided. Each converter leg includes a first string including a plurality of switches coupled to each other in series. The one or more converter legs also include a second string operatively coupled to the first string at a first node and a second node in a parallel configuration, where the second string includes a plurality of switching units, and where a second string of one converter leg of the one or more converter legs is operatively coupled to second strings corresponding to other converter legs in the one or more converter legs.

Abstract: A power converter includes at least one leg having a first string operatively coupled to a second string via a first connecting node and a second connecting node. The first string includes a first branch and a second branch operatively coupled via a third connecting node. Each of the branches has a plurality of switching units, a controllable semiconductor switch and the first connecting node and the second connecting node. The first string is operatively coupled across a first bus and a second bus. Furthermore, the second string includes a plurality of controllable semiconductor switches.

Abstract: A modular embedded multi-level converter (MEMC) includes a first phase portion and a second phase portion. The first phase portion includes a first switch stack operable to couple a first phase branch between a positive DC bus and a midpoint node. The second phase portion includes a second switch stack operable to couple a second phase branch between the midpoint node and a negative DC bus. A DC voltage between the positive DC bus and the negative DC bus is distributable among switching units disposed in the first phase branch and the second phase branch. A distribution of the DC voltage is controlled by regulating a DC voltage at the midpoint node to balance energy among the switching units.

Abstract: A power converter is provided. The power converter includes at least one leg. The at least one leg of the power converter includes a plurality of switching units. The switching units are coupled with each other in a serial fashion. Further, in the power converter, the switching units are selected such that at least two switching units in the power converter have different operating voltages.

Abstract: A power converter includes at least one leg with a first string including a plurality of controllable semiconductor switches, a first connecting node, and a second connecting node, wherein the first string is operatively coupled across a first bus and a second bus. The at least one leg also includes a second string operatively coupled to the first string via the first connecting node and the second connecting node, wherein the second string includes a plurality of switching units. The first string includes a first branch and a second branch, wherein the second branch is operatively coupled to the first branch via a third connecting node and the third connecting node is coupled to a ground connection.

Abstract: A modular embedded multi-level converter (MEMC) includes a first phase portion and a second phase portion. The first phase portion includes a first switch stack operable to couple a first phase branch between a positive DC bus and a midpoint node. The second phase portion includes a second switch stack operable to couple a second phase branch between the midpoint node and a negative DC bus. A DC voltage between the positive DC bus and the negative DC bus is distributable among switching units disposed in the first phase branch and the second phase branch. A distribution of the DC voltage is controlled by regulating a DC voltage at the midpoint node to balance energy among the switching units.

Abstract: A system for driving an electric machine is provided. The system includes a power converter coupled to an input source and the electric machine. The power converter includes a leg that includes a first and second string. The first string includes plurality of controllable semiconductor switches, a first and second connecting node. The first string is operatively coupled across a first and second bus. The second string is operatively coupled to the first string via the first and second connecting node. The second string comprises plurality of switching modules. The switching modules include fully controllable semiconductor switches and energy storage devices. The system further includes a system controller configured to provide activation commands to the controllable semiconductor switches and the switching modules such that energy stored in the energy storage device is provided to the electric machine when the machine is switched on for operation.

Abstract: A power converter includes at least one leg having a first string operatively coupled to a second string via a first connecting node and a second connecting node. The first string includes a first branch and a second branch operatively coupled via a third connecting node. Each of the branches has a plurality of switching units, a controllable semiconductor switch and the first connecting node and the second connecting node. The first string is operatively coupled across a first bus and a second bus. Furthermore, the second string includes a plurality of controllable semiconductor switches.

Abstract: A power converter includes at least one leg including a first string that includes controllable semiconductor switches, a first connecting node, and a second connecting node and that is operatively coupled across a first bus and a second bus. A second string is operatively coupled to the first string via the first connecting node and the second connecting node. The second string includes a plurality of switching modules wherein each of the plurality of switching modules includes a plurality of fully controllable semiconductor switches and at least one energy storage device. The power converter includes a system controller to control activation of the controllable semiconductor switches and switching modules such that a controlled electrical variable is maintained at a first predetermined reference voltage value and the average internal stored energy of the energy storage devices is maintained at a second predetermined reference value.

Abstract: A power converter including one or more converter legs is provided. Each converter leg includes a first string including a plurality of switches coupled to each other in series. The one or more converter legs also include a second string operatively coupled to the first string at a first node and a second node in a parallel configuration, where the second string includes a plurality of switching units, and where a second string of one converter leg of the one or more converter legs is operatively coupled to second strings corresponding to other converter legs in the one or more converter legs.

Abstract: A system includes a generator unit coupleable to a hydro turbine. The generator unit includes a casing having a first stationary support coupleable to a base disposed within water and a superconducting generator disposed within the casing. The superconducting generator includes an annular armature and an annular field winding including a plurality of superconducting magnets disposed coaxial with the annular armature and separated by a gap. One of the annular armature and the annular field winding is rotatable by the hydro turbine and other of the annular armature and the annular field winding is stationary.

Abstract: A system for driving an electric machine is provided. The system includes a power converter coupled to an input source and the electric machine. The power converter includes a leg that includes a first and second string. The first string includes plurality of controllable semiconductor switches, a first and second connecting node. The first string is operatively coupled across a first and second bus. The second string is operatively coupled to the first string via the first and second connecting node. The second string comprises plurality of switching modules. The switching modules include fully controllable semiconductor switches and energy storage devices. The system further includes a system controller configured to provide activation commands to the controllable semiconductor switches and the switching modules such that energy stored in the energy storage device is provided to the electric machine when the machine is switched on for operation.

Abstract: A power converter includes at least one leg including a first string that includes controllable semiconductor switches, a first connecting node, and a second connecting node and that is operatively coupled across a first bus and a second bus. A second string is operatively coupled to the first string via the first connecting node and the second connecting node. The second string includes a plurality of switching modules wherein each of the plurality of switching modules includes a plurality of fully controllable semiconductor switches and at least one energy storage device. The power converter includes a system controller to control activation of the controllable semiconductor switches and switching modules such that a controlled electrical variable is maintained at a first predetermined reference voltage value and the average internal stored energy of the energy storage devices is maintained at a second predetermined reference value.

Abstract: A power converter is provided. The power converter includes at least one leg. The at least one leg of the power converter includes a plurality of switching units. The switching units are coupled with each other in a serial fashion. Further, in the power converter, the switching units are selected such that at least two switching units in the power converter have different operating voltages.

Abstract: A power converter module is provided. The power converter module includes a first converter leg and a second converter leg. The first converter leg includes a first switching unit and a second switching unit coupled in series. The second switching unit is disposed in a reverse orientation with respect to an orientation of the first switching unit. The second converter leg includes a third switching unit and a diode coupled in series. The third switching unit is disposed in a reverse orientation with respect to the orientation of the first switching unit. The power converter also includes a first energy storage device operatively coupled between the first converter leg and the second converter leg. The power converter module further includes a second energy storage device operatively coupled between the first converter leg and the second converter leg.

Abstract: A power converter includes at least one leg with a first string including a plurality of controllable semiconductor switches, a first connecting node, and a second connecting node, wherein the first string is operatively coupled across a first bus and a second bus. The at least one leg also includes a second string operatively coupled to the first string via the first connecting node and the second connecting node, wherein the second string includes a plurality of switching units. The first string includes a first branch and a second branch, wherein the second branch is operatively coupled to the first branch via a third connecting node and the third connecting node is coupled to a ground connection.