The present disclosure relates to a voltage source converter (VSC) (300) comprising: a first MOSFET switching element (302) including a first body diode (306); a second MOSFET switching element (304) including a second body diode (308), the second MOSFET switching element (304) being connected in series with the first MOSFET switching element (302); a protection device (318) connected in parallel with the second MOSFET switching element (304); and a controller (312), wherein the controller (312) is configured, on detection of an overcurrent event, to: switch off the first MOSFET switching element (302); and switch off the second MOSFET switching element (304), thereby forcing current flowing in the VSC (300) following the overcurrent event to flow through the second body diode (308) rather than through conducting channels of the first and second MOSFET switching elements (302, 304).

The present disclosure relates to a voltage source converter (VSC) (300) comprising: a first MOSFET switching element (302) including a first body diode (306); a second MOSFET switching element (304) including a second body diode (308), the second MOSFET switching element (304) being connected in series with the first MOSFET switching element (302); a protection device (318) connected in parallel with the second MOSFET switching element (304); and a controller (312), wherein the controller (312) is configured, on detection of an overcurrent event, to: switch off the first MOSFET switching element (302); and switch off the second MOSFET switching element (304), thereby forcing current flowing in the VSC (300) following the overcurrent event to flow through the second body diode (308) rather than through conducting channels of the first and second MOSFET switching elements (302, 304).

A power conversion system includes: a first power converter to perform power conversion between a first AC system and a DC circuit; and a second power converter to perform power conversion between a second AC system and the DC circuit. Each of the first power converter and the second power converter includes a plurality of submodules connected in series. Each of the plurality of submodules includes a plurality of switching elements and a capacitor. A first fundamental frequency of the first AC system is greater than a second fundamental frequency of the second AC system. A first average voltage value of a capacitor in a first submodule included in the first power converter is larger than a second average voltage value of a capacitor in a second submodule included in the second power converter.

A utility-scale energy storage and conversion system can operate two or more inverter groups such that their reactive power commands are proportional to their available reactive power range. The control system can therefore distribute the reactive power commands in proportion to the available Q range, thereby ensuring that all inverters in the utility-scale energy storage and conversion system 100 operate with the same Q “headroom”. In addition, the utility-scale energy storage and conversion system can use an on-load tap changer (LTC) to adjust a terminal voltage associated with a first group of inverters and a second group of inverters. The first group of inverters can be associated with a first rating and the second group of inverters can be associated with a second rating that is greater than the first rating.

A utility-scale energy storage and conversion system can operate two or more inverter groups such that their reactive power commands are proportional to their available reactive power range. The control system can therefore distribute the reactive power commands in proportion to the available Q range, thereby ensuring that all inverters in the utility-scale energy storage and conversion system 100 operate with the same Q “headroom”. In addition, the utility-scale energy storage and conversion system can use an on-load tap changer (LTC) to adjust a terminal voltage associated with a first group of inverters and a second group of inverters. The first group of inverters can be associated with a first rating and the second group of inverters can be associated with a second rating that is greater than the first rating.

A semiconductor switch drive device (3) includes a drive unit (10), a power supply unit (20), a switch (39), and a control unit (50). The drive unit (10) supplies a control signal to a semiconductor switch (Q) of a main circuit (2) and drives the semiconductor switch (Q). The power supply unit (20) supplies electric power to the drive unit (10). The switch (39) cuts off supply of electric power to the power supply unit (20) by detecting or controlling an overvoltage state on a primary side of the power supply unit (20). The control unit (50) switches a conductive state of the switch (39) on the basis of a voltage of a control terminal of the semiconductor switch (Q).

A semiconductor switch drive device (3) includes a drive unit (10), a power supply unit (20), a switch (39), and a control unit (50). The drive unit (10) supplies a control signal to a semiconductor switch (Q) of a main circuit (2) and drives the semiconductor switch (Q). The power supply unit (20) supplies electric power to the drive unit (10). The switch (39) cuts off supply of electric power to the power supply unit (20) by detecting or controlling an overvoltage state on a primary side of the power supply unit (20). The control unit (50) switches a conductive state of the switch (39) on the basis of a voltage of a control terminal of the semiconductor switch (Q).

To provide a multi-phase power conversion device control circuit capable of preventing switching elements and driver circuits of a multi-phase power conversion device from being damaged even when arm short circuits have occurred to a plurality of phases simultaneously. The control circuit includes: a current detection unit configured to detect a current flowing through the switching element as a voltage value; an overcurrent detection unit configured to, when a voltage value detected by the current detection unit is higher than a first reference voltage, output an individual overcurrent detection signal Scu; and an overcurrent state control unit configured to, when overcurrent state is detected at the current detection unit of each of two or more phases, output a multi-phase overcurrent signal and short-circuit the control terminal of the switching element to an emitter terminal thereof.

To provide a multi-phase power conversion device control circuit capable of preventing switching elements and driver circuits of a multi-phase power conversion device from being damaged even when arm short circuits have occurred to a plurality of phases simultaneously. The control circuit includes: a current detection unit configured to detect a current flowing through the switching element as a voltage value; an overcurrent detection unit configured to, when a voltage value detected by the current detection unit is higher than a first reference voltage, output an individual overcurrent detection signal Scu; and an overcurrent state control unit configured to, when overcurrent state is detected at the current detection unit of each of two or more phases, output a multi-phase overcurrent signal and short-circuit the control terminal of the switching element to an emitter terminal thereof.

A high-voltage waveform generator comprising a power source, a transformer unit comprising a magnetic core, attached to the power source, a plurality of power switch cards, each having an aperture that allows said magnetic core to pass therethrough, one or more control switches located on each power card, and a control means for actuating the control switches, a power output; wherein the power switch cards are connected in series, wherein each of the apertures in the power switch cards is surrounded by conductive windings, whereby when the power source is activated, the magnetic core induces a current in each of the conductive windings, and wherein the control means activates the control switches simultaneously in under 100 nanoseconds to generate a pulse.