Abstract: An electrical converter includes a main converter for generating a first output voltage and a converter cell for converting the first output voltage into a second output voltage. A method for operating an electrical converter includes: receiving a reference voltage for the electrical converter; pulse width modulating the reference voltage with a first modulation frequency for generating a first switching signal for the main converter; switching the main converter with the first switching signal to generate the first output voltage; estimating the first output voltage from the first switching signal; determining a voltage error by subtracting the estimated first output voltage from the reference voltage; pulse width modulating the voltage error with a second modulation frequency, which is higher than the first modulation frequency, for generating a further switching signal for the converter cell; and switching the converter cell with the further switching signal to generate the second output voltage.

Abstract: A grid forming vector current control system can be used for controlling a grid intertie. A first terminal is connected to a first power grid and a second terminal is connected to a second power grid. The terminals each include current control unit, a virtual admittance unit, and a phase locked loop (PLL) unit. The virtual admittance unit and the PLL unit are configured to emulate an inertia of a virtual synchronous machine (VSM) and a virtual current source is connected in parallel to the VSM. A controller is configured to use transient power consumed by the first VSM to generate a power-equivalent current reference to control the second virtual current source and to use transient power consumed by the second VSM to generate a power-equivalent current reference to control the first virtual current source.

Abstract: A grid forming vector current control system can be used for controlling a grid intertie. A first terminal is connected to a first power grid and a second terminal is connected to a second power grid. The terminals each include current control unit, a virtual admittance unit, and a phase locked loop (PLL) unit. The virtual admittance unit and the PLL unit are configured to emulate an inertia of a virtual synchronous machine (VSM) and a virtual current source is connected in parallel to the VSM. A controller is configured to use transient power consumed by the first VSM to generate a power-equivalent current reference to control the second virtual current source and to use transient power consumed by the second VSM to generate a power-equivalent current reference to control the first virtual current source.

Abstract: A system and method for compensating a faulty switch in a multi-level flying capacitor converter includes a converter capacitor arranged in parallel to an input, a first and second converter switches arranged respectively between first and second ends of the converter capacitor, first and second bypass switches respectively arranged in parallel to the first and second converter switches, wherein operation includes detecting a faulty converter level that includes at least one of the first and second converter switches, discharging all capacitors arranged in parallel to the input of the multi-level converter, wherein all capacitors comprise the converter capacitors and an input capacitor; closing the first and second bypass switches of the faulty converter level; adapting a modulation of the converter switches of the other converter levels; and restarting the multi-level converter.

Abstract: A modulator for a flying-capacitor type multilevel converter receives, at an input, a time-variant reference signal and provides, at an output, a sequence of target levels, to provide switching signals for switching between discrete output levels of the multilevel converter according to the shape of the reference signal. The modulator determines a critical level as an intermediate output level of the multilevel converter which is closest to the level of the reference signal; and outputs only target levels corresponding to output levels different from the critical level.

Abstract: Described herein is a method of operating a power electronic converter device for an electrical power conversion system. The power electronic converter device includes a converter circuit including an input side, an output side, a first converter, and at least one second converter. The second converter includes at least one floating cell with a DC intermediate circuit and semiconductor devices. The method includes: switching the semiconductor devices of the floating cell at switching instants determined with optimized pulse patterns or carrier-based pulse width modulation; determining a fundamental voltage component for the floating cell; and generating the fundamental voltage component in the actual voltage of the floating cell by modifying the switching instants, such that a voltage VC AF of the DC intermediate circuit is lying in a given reference voltage range for balancing the DC intermediate circuit of the floating cell.

Abstract: A protection circuit for a power converter with cascaded bipolar and/or unipolar semiconductors is provided. The protection circuit includes at least one comparator circuit which is adapted to monitor a voltage characteristic on a collector-emitter path of at least one semiconductor which is arranged in a polarity selection stage of the power converter and/or to monitor a voltage characteristic on at least one capacitor, which is arranged in the power converter. The at least one comparator circuit is further adapted to output an electrical signal, representing the voltage characteristic of the semiconductor and/or the at least one capacitor to at least one evaluation unit. The at least one evaluation unit is further adapted to evaluate the result from the at least one comparator circuit and to deactivate the semiconductors in case that the voltage characteristic of the semiconductors and/or the capacitors deviate from a predetermined threshold.

Abstract: The present disclosure provides a grid forming vector current control system configured to emulate a virtual synchronous machine (VSM). The disclosed system comprises a droop control unit, a current control unit, a virtual admittance unit and a phase locked loop (PLL) unit. The virtual admittance unit and the PLL unit are configured to emulate an inertia of the VSM. A virtual current source is connected in parallel to the VSM.

Abstract: A flying capacitor switching cell-system includes at least two flying capacitor switching cells, wherein each of the cells comprises an arrangement of at least one semiconductor system, and wherein the cells are in parallel in an electrical circuit.

Abstract: A converter system includes a rectifier, a DC link stage and an inverter connected in series. A control unit includes a slow reference frame angle determination unit that generates a slow reference frame angle ?r,slow representing an angle that is slowly following a grid phase deviation, and a fast Phase Locked Loop generating a fast reference frame angle ?r,fast representing an angle that is fast following a grid phase deviation. The control unit uses the slow reference frame angle ?r,slow and the fast reference frame angle ?r,fast to control the rectifier output current, and the fast reference frame angle ?r,fast to control the inverter output voltage and to synchronize the inverter output voltage with the grid voltage.

Abstract: An electrical converter (10) comprises a main converter (12) for generating a first output voltage (u1abc) and a converter cell (14a) for converting the first output voltage (u1abc) into a second output voltage (u2abc).

Abstract: A protection circuit for a power converter with cascaded bipolar and/or unipolar semiconductors is provided. The protection circuit includes at least one comparator circuit which is adapted to monitor a voltage characteristic on a collector-emitter path of at least one semiconductor which is arranged in a polarity selection stage of the power converter and/or to monitor a voltage characteristic on at least one capacitor, which is arranged in the power converter. The at least one comparator circuit is further adapted to output an electrical signal, representing the voltage characteristic of the semiconductor and/or the at least one capacitor to at least one evaluation unit. The at least one evaluation unit is further adapted to evaluate the result from the at least one comparator circuit and to deactivate the semiconductors in case that the voltage characteristic of the semiconductors and/or the capacitors deviate from a predetermined threshold.

Abstract: A method for controlling a converter system includes: determining, with a first controller stage, an output voltage reference for the converter system; generating, with the first controller stage, switching commands for a main converter based on the output voltage reference, such that the main converter converts an input voltage into an intermediate voltage provided at an output of the main converter and following the output voltage reference; and generating, with a second controller stage, switching commands for a floating converter cell connected to the output of the main converter, such that the floating converter cell converts the intermediate voltage into an output voltage provided at an output of the floating converter cell, wherein the floating converter cell comprises a cell capacitor and a semiconductor switch arrangement for connecting and disconnecting the cell capacitor between the output of the main converter and the output of the floating converter cell.

Abstract: An electrical machine includes a stator core and a plurality of windings subdivided into a plurality of multiphase motor cells, each multiphase motor cell having M windings associated therewith, and having a phase shift relative to other multiphase motor cells. The electrical machine may include N inverter cells coupled in series; wherein each inverter cell is a multiphase inverter; and wherein the voltage magnitude supplied to a corresponding multiphase motor cell is VDC/N. The electrical machine may include a sensor system in communication with the plurality of inverter cells and operative to commutate each inverter cell in a sequence.

Abstract: An inverter system for a photovoltaic panel includes: an inverter adapted for transforming a DC voltage from the photovoltaic panel into an AC voltage to be supplied to an electrical grid; a DC link interconnected with the inverter and providing a positive DC link output connectable to a positive pole of the photovoltaic panel and a negative DC link output connectable to a negative pole of the photovoltaic panel; a switch for disconnecting the negative pole of the photovoltaic panel from the DC link; and a controller for controlling the inverter and the switch; wherein the controller is adapted for opening the switch, such that the photovoltaic panel is solely supplyable by the positive DC link output.

Abstract: A method for controlling a converter system includes: determining, with a first controller stage, an output voltage reference for the converter system; generating, with the first controller stage, switching commands for a main converter based on the output voltage reference, such that the main converter converts an input voltage into an intermediate voltage provided at an output of the main converter and following the output voltage reference; and generating, with a second controller stage, switching commands for a floating converter cell connected to the output of the main converter, such that the floating converter cell converts the intermediate voltage into an output voltage provided at an output of the floating converter cell, wherein the floating converter cell comprises a cell capacitor and a semiconductor switch arrangement for connecting and disconnecting the cell capacitor between the output of the main converter and the output of the floating converter cell.

Abstract: The subject matter described herein includes a multiphase fractional slot concentrated winding machine. One such machine includes a machine module including a rotor and a stator. The stator includes a plurality of radially extending teeth. Each tooth is individually wound with a coil. The machine further includes a multiphase series converter circuit physically connected to an end of the machine module to energize the coils for multiphase operation.

Abstract: A bridge converter for a multi-phase electrical machine has a number of bridge cells connected in series. Each bridge cell has a controller. The bridge converter includes a sensor operative to provide a commutation signal to at least one controller. A multi-phase electrical machine has a plurality of stator windings and a bridge converter having a number of bridge cells connected in series. Each bridge cell has a controller. The bridge converter includes a sensor operative to provide a commutation signal to at least one controller.

Abstract: An electrical machine includes a stator core and a plurality of windings subdivided into a plurality of multiphase motor cells, each multiphase motor cell having M windings associated therewith, and having a phase shift relative to other multiphase motor cells. The electrical machine may include N inverter cells coupled in series; wherein each inverter cell is a multiphase inverter; and wherein the voltage magnitude supplied to a corresponding multiphase motor cell is VDC/N. The electrical machine may include a sensor system in communication with the plurality of inverter cells and operative to commutate each inverter cell in a sequence.

Abstract: A bridge converter for a multi-phase electrical machine has a number of bridge cells connected in series. Each bridge cell has a controller. The bridge converter includes a sensor operative to provide a commutation signal to at least one controller. A multi-phase electrical machine has a plurality of stator windings and a bridge converter having a number of bridge cells connected in series. Each bridge cell has a controller. The bridge converter includes a sensor operative to provide a commutation signal to at least one controller.