The present invention proposes a hybrid converter branch operating mode for a Modular Multilevel power Converter MMC with MMC cells in distinct subsets operating according to a “pulse blocked” cell operation mode with DC cell voltage increase or according to a “bypass” cell operation mode without DC cell voltage increase. Repeated cell subset assignment and corresponding alternation of cell operating mode allows to reduce or at least manage a mean deviation of the cell capacitor DC voltages of the converter cells. The invention also reduces no-load losses of the MMC in standby mode and a charging voltage in an MMC charging mode.

The present invention proposes a hybrid converter branch operating mode for a Modular Multilevel power Converter MMC with MMC cells in distinct subsets operating according to a “pulse blocked” cell operation mode with DC cell voltage increase or according to a “bypass” cell operation mode without DC cell voltage increase. Repeated cell subset assignment and corresponding alternation of cell operating mode allows to reduce or at least manage a mean deviation of the cell capacitor DC voltages of the converter cells. The invention also reduces no-load losses of the MMC in standby mode and a charging voltage in an MMC charging mode.

The invention generally relates to methods and circuits for controlling switching of parallel coupled power semiconductor switching devices (3), for example for use in a power converter. In an example, there is provided a circuit for controlling switching of parallel coupled power semiconductor switching devices (3), the circuit comprising: a plurality of drive modules (2), each said module for controlling a said power semiconductor switching device (3); control circuitry to transmit switch command signals to the modules, each said switch command signal to trigger a said drive module to control a said power semiconductor switching device to switch state; and voltage isolation between the drive modules and the control circuitry, wherein each said drive module for controlling a said device comprises: timing circuitry (22) to compare a switching delay of the device and a reference delay, wherein said switching delay is a time interval between detecting a said switching command signal at the drive module and switching of the device in accordance with the detected switching command signal; and delay circuitry (21) to provide a controllable delay to delay a said triggering by a said switching command signal received at the module subsequent to the detected switching command signal, the delay circuitry configured to control the controllable delay according to a result of said comparison of said switching delay of the device, to thereby reduce a time difference between the reference delay and a said switching delay of the device switching in accordance with the subsequent switching command signal.

The present disclosure relates to a method for controlling a converter, in particular power converter of a wind power installation. The converter has a plurality of, preferably parallel, converter modules. The method includes the following steps: driving a first converter module, such that the converter module generates a first electrical AC current in a first switch position, driving a second converter module, such that the converter module generates a second electrical AC current in a second switch position, superposing the first electrical AC current and the second electrical AC current to form a total current, detecting the total current of the converter, determining a virtual current depending on the first and second switch positions, and changing the first switch position of the first converter module and/or the second switch position of the second converter module depending on the total current and the virtual current.

A three-phase power supply system includes three phase branches forming a delta connection. Each of the phase branches includes at least one power conversion cell of at least two stages. The at least one power conversion cell of each of the phase branches is connected in parallel to the at least one power conversion cell of the respective other two phase branches. When one of the phase branches stops operating, the other two phase branches keep operating, and three phase current of the three-phase power supply system can be balanced by regulating active powers and reactive powers of the other two phase branches. Through the invention, when one of the phase branches stops operating, the other two phase branches may keep operating, and three phase current of the three-phase power supply system are balanced.

A three-phase power supply system includes three phase branches forming a delta connection. Each of the phase branches includes at least one power conversion cell of at least two stages. The at least one power conversion cell of each of the phase branches is connected in parallel to the at least one power conversion cell of the respective other two phase branches. When one of the phase branches stops operating, the other two phase branches keep operating, and three phase current of the three-phase power supply system can be balanced by regulating active powers and reactive powers of the other two phase branches. Through the invention, when one of the phase branches stops operating, the other two phase branches may keep operating, and three phase current of the three-phase power supply system are balanced.

The present disclosure relates to a high voltage inverter system and a method for synchronizing the size and a phase of a high voltage inverter using same, and particularly to a high voltage inverter system which synchronizes the size and a phase of power output from a high voltage inverter with commercial power during a static transfer, and a method for synchronizing the size and a phase of the high voltage inverter using same. The high voltage inverter system according to the present disclosure synchronizes the size and a phase of voltage output from the high voltage inverter with commercial power, and thus may minimize electric shock during a static transfer from high voltage inverter power to commercial power.

A power system with communication function applied to a solid state transformer structure includes a plurality of conversion units, a bus path, a plurality of coupling units, and a control module. The conversion units are coupled to the bus path and the coupling units, and the coupling units are coupled to the control module. Each coupling unit is correspondingly coupled to a control unit of each conversion unit. A first-connected coupling unit of the coupling units is coupled to the control module.

A power system with communication function applied to a solid state transformer structure includes a plurality of conversion units, a bus path, a plurality of coupling units, and a control module. The conversion units are coupled to the bus path and the coupling units, and the coupling units are coupled to the control module. Each coupling unit is correspondingly coupled to a control unit of each conversion unit. A first-connected coupling unit of the coupling units is coupled to the control module.

In a system and method for operating a system having a rectifier which is suppliable from an electric AC-voltage supply network, an inverter which feeds an electric motor, and a DC/DC converter which is connected to an energy accumulator, the DC-voltage side connection of the inverter is connected to the DC-voltage side connection of the rectifier, in particular, the electric motor is supplied from the AC-voltage side connection of the inverter, a first DC-voltage side connection of the DC/DC converter is connected to the DC-voltage side connection of the rectifier, in particular, the DC-voltage side connection of the inverter and the first DC-voltage side connection of the DC/DC converter are connected in parallel, the DC/DC converter has a housing in which a device for current acquisition is situated, which acquires either the current, in particular network phase currents, flowing into the rectifier at the AC-voltage side connection of the rectifier, or the current emerging from the rectifier at the DC-voltage side connection of the rectifier, and the acquired value is forwarded to a signal electronics situated in the housing of the DC/DC converter, which generates control signals for semiconductor switches of the DC/DC converter.