A method of clamping an output current of a three-phase power converter is provided. The three-phase power converter includes three switching bridge arms and provides a three-phase output voltage command, and each switching bridge arm has an upper switch and a lower switch connected in series. The method includes steps of: determining that the output current is greater than a first current threshold to activate a current clamping control procedure, comparing a carrier signal with the three-phase output voltage command to turn on the lower switches by a first zero vector when the carrier signal is rising and turn on the upper switches by a second zero vector when the carrier signal is falling, determining that the output current is greater than a second current threshold to activate an overcurrent protection procedure, wherein the second current threshold is greater than the first current threshold.

A method of clamping an output current of a three-phase power converter is provided. The three-phase power converter includes three switching bridge arms and provides a three-phase output voltage command, and each switching bridge arm has an upper switch and a lower switch connected in series. The method includes steps of: determining that the output current is greater than a first current threshold to activate a current clamping control procedure, comparing a carrier signal with the three-phase output voltage command to turn on the lower switches by a first zero vector when the carrier signal is rising and turn on the upper switches by a second zero vector when the carrier signal is falling, determining that the output current is greater than a second current threshold to activate an overcurrent protection procedure, wherein the second current threshold is greater than the first current threshold.

A bridge circuit includes a first leg and a second leg arranged in parallel between the first node and the third node. A clamp circuit includes a third leg including a first bidirectional switch disposed between a fourth node that is a midpoint of the first leg and a fifth node that is a midpoint of the second leg. A first reactor is connected with the fourth node and a sixth node, and a second reactor is connected with a fifth node and a seventh node. A fourth leg includes a second bidirectional switch disposed between the second node and the fourth node or the fifth node.

A bridge circuit includes a first leg and a second leg arranged in parallel between the first node and the third node. A clamp circuit includes a third leg including a first bidirectional switch disposed between a fourth node that is a midpoint of the first leg and a fifth node that is a midpoint of the second leg. A first reactor is connected with the fourth node and a sixth node, and a second reactor is connected with a fifth node and a seventh node. A fourth leg includes a second bidirectional switch disposed between the second node and the fourth node or the fifth node.

In order to protect an inverter from prohibited switching states, a monitor including monitoring inputs and monitoring outputs is provided. The monitoring inputs are connected to the control outputs in order to receive the switching patterns, and the monitoring outputs are connected to the power switches. The monitor is designed to compare a transition from a first switching pattern to a second switching pattern with a number of prohibited transitions and/or with a number of permitted transitions and block the second switching pattern in the event of a match with one of the prohibited transitions and/or in the event of a deviation from the number of permitted transitions and to output the second switching pattern to the power switches via the monitoring outputs in the event of a deviation from the number of prohibited transitions and/or in the event of a match with one of the permitted transitions.

In order to protect an inverter from prohibited switching states, a monitor including monitoring inputs and monitoring outputs is provided. The monitoring inputs are connected to the control outputs in order to receive the switching patterns, and the monitoring outputs are connected to the power switches. The monitor is designed to compare a transition from a first switching pattern to a second switching pattern with a number of prohibited transitions and/or with a number of permitted transitions and block the second switching pattern in the event of a match with one of the prohibited transitions and/or in the event of a deviation from the number of permitted transitions and to output the second switching pattern to the power switches via the monitoring outputs in the event of a deviation from the number of prohibited transitions and/or in the event of a match with one of the permitted transitions.

Power converter for converting between a DC voltage and a AC voltage. The power converter may include: a DC link with a series of three capacitors, the outer nodes of the series forming an upper and a lower DC terminal and connection points between the capacitors forming an upper and a lower intermediate voltage node; and one or more phase legs. Each phase leg includes: an upper switch series between the upper DC terminal and the lower intermediate voltage node, with two semiconductor switches; a lower switch series between the lower DC terminal and the upper intermediate voltage node, with two semiconductor switches; and an inner switch series between the midpoints of the upper and the lower switch series, the inner switch series comprising two semiconductor switches, the midpoint forming an AC terminal of the power converter, wherein the semiconductor switches of the inner switch series are bidirectional semiconductor switches.

Power converter for converting between a DC voltage and a AC voltage. The power converter may include: a DC link with a series of three capacitors, the outer nodes of the series forming an upper and a lower DC terminal and connection points between the capacitors forming an upper and a lower intermediate voltage node; and one or more phase legs. Each phase leg includes: an upper switch series between the upper DC terminal and the lower intermediate voltage node, with two semiconductor switches; a lower switch series between the lower DC terminal and the upper intermediate voltage node, with two semiconductor switches; and an inner switch series between the midpoints of the upper and the lower switch series, the inner switch series comprising two semiconductor switches, the midpoint forming an AC terminal of the power converter, wherein the semiconductor switches of the inner switch series are bidirectional semiconductor switches.

A submodule for a modular multilevel converter has nine semiconductor switches that can be switched off, four capacitors, six network nodes, and two terminals. The components are mounted such that different voltages are generated between the terminals of the submodule by controlling the semiconductor switches. This arrangement of components substantially improves the behavior of the converter and of the submodule in the event of a fault.

A power conversion device is provided between a power supply and a load, and converts power from the power supply and supplies the converted power to the load. The power conversion device includes a plurality of switching elements composed of semiconductor elements, and a control device which generates drive signals for controlling the plurality of switching elements. Voltages are respectively applied to the plurality of semiconductor elements, on the basis of the drive signals generated by the control device. The plurality of semiconductor elements have equivalent failure probabilities due to neutron beams. Thus, a failure of the power conversion device due to neutron beams is prevented, and size increase thereof is suppressed.