Semiconductor protection elements for controlling short circuits at the DC end of voltage source converters

摘要

A device for converting an electric current includes at least one phase module having an AC terminal and at least one DC terminal. Phase module branches, each of which is equipped with serially connected submodules, are respectively provided between each DC terminal and each AC terminal. Each submodule is provided with at least one power semiconductor. Semiconductor protecting means are connected in parallel or in series to at least one of the power semiconductors to enable the device to withstand even high short-circuit currents for a sufficient period of time. A method for protecting the power semiconductors of the device, is also provided.

主权项

1. A device for converting an electric current, the device comprising:
at least one phase module having an AC voltage connection, at least one DC voltage connection, and at least one phase module branch respectively disposed between each said at least one DC voltage connection and said AC voltage connection; said at least one phase module branch each including a series circuit of submodules, each submodule including at least one turn-off power semiconductor and a freewheeling diode reverse connected in parallel with said at least one turn-off power semiconductor; said at least one semiconductor protection device including a freewheeling diode or thyristor connected in parallel with said freewheeling diode reverse connected in parallel with said at least one turn-off power semiconductor; each of said submodules additionally including a first connection terminal, a second connection terminal, an energy storage device and a power semiconductor branch connected in parallel with said energy storage device, said energy storage device connected to said power semiconductor branch in both directions by low resistant and low inductive current path; said at least one turn-off power semiconductor including first and second series-connected turn-off power semiconductors of said power semiconductor branch each having an emitter; freewheeling diodes each reverse connected in parallel with a respective one of said turn-off power semiconductors and each having an anode; a junction point of said emitter of said first turn-off power semiconductor of said power semiconductor branch and said anode of said freewheeling diode assigned to said first turn-off power semiconductor, forms said first connection terminal; and a junction point of said turn-off power semiconductors of said power semiconductor branch and said freewheeling diodes forms said second connection terminal.