A DC power transmission system interconnects a plurality of AC systems via a DC line. A plurality of power conversion devices are connected between the plurality of AC systems and the DC line. One of the plurality of power conversion devices controls the voltage on the DC line, while the remaining power conversion device controls a current input and output to and from the DC line. In a restart which resumes power conversion from a stopped state for controlling a DC current on the DC line, the power conversion device performing current control monitors the voltage on the DC line and starts a restart operation without transmitting or receiving information to or from the other power conversion device.

An electrical circuit for charging a DC voltage source from an AC voltage network. The circuit includes an input that is able to receive an AC voltage from the voltage network, and a first output able to be connected to the DC voltage source. An insulating stage formed using a plurality of capacitors is arranged so as to electrically insulate the input from the first output of the circuit. A frequency-raising stage is arranged between the input of the circuit and the insulating stage so that the capacitors of the insulating stage are in a circuit portion that has flowing through it an AC current at a frequency that is greater than that of the AC network.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

Embodiments of the invention provide a 3-phase rectifying circuit that may produce a DC voltage with much less ripple compared to a single-phase rectifying circuit. In one aspect, the circuit or switch of embodiments of the invention may provide a filtered DC voltage to drive a LED string formed by multiple LED units.

A converter module for a multi-stage converter includes an energy storage device connected in parallel with a series circuit of a first and a second semiconductor switching unit. At least one of the semiconductor switching units has a bidirectional switch. A switch-on unit is connected in parallel with the bidirectional switch. With the switch-on unit there can be produced a switch-on voltage for switching on the bidirectional switch from a voltage dropping across the bidirectional switch. There is also disclosed a multi-stage converter having the novel converter module and a method for operating the converter module.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

A converter module for a multi-stage converter includes an energy storage device connected in parallel with a series circuit of a first and a second semiconductor switching unit. At least one of the semiconductor switching units has a bidirectional switch. A switch-on unit is connected in parallel with the bidirectional switch. With the switch-on unit there can be produced a switch-on voltage for switching on the bidirectional switch from a voltage dropping across the bidirectional switch. There is also disclosed a multi-stage converter having the novel converter module and a method for operating the converter module.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.