Modular multi-stage inverter comprising surge arrester
View Patent ↗Electric power is transferred between an AC voltage grid and a DC voltage grid in the high-voltage range. Phase modules have at least one common DC voltage connection and separate AC voltage connections. A phase module branch between the DC voltage connection and each AC voltage connection has a series circuit of two-pole sub-modules, each with an energy storage device and a power semiconductor circuit in parallel with the energy storage device. The power semiconductor circuit is driven to generate either the voltage drop across the energy storage device or else a zero voltage at the two sub-module connection terminals. A converter transformer has a primary side on an AC voltage grid and a secondary side connected to the AC voltage connections. Improved protection against overloading is provided by at least one surge arrester between the or one of the common DC voltage connections and the inverter neutral point.
1. A device for transferring electrical power between an AC voltage network and a DC voltage network in a high-voltage range, the device comprising:
a plurality of phase modules each having two shared DC voltage terminals and each having a separate AC voltage terminal;
a respective phase module branch extending between each said DC voltage terminal and each said AC voltage terminal, said phase module branch including a series circuit with two-pole sub-modules each having two sub-module connection terminals;
each said two-pole sub-module having an energy storage device and a power semiconductor circuit connected in parallel with said energy storage device, and wherein, depending on a control of said power semiconductor circuit either the voltage dropping across said energy storage device or a zero voltage is generated at said two sub-module connection terminals;
a converter transformer having a primary side connected or connectable to an AC voltage network, said converter transformer having a secondary side connected or connectable to each said AC voltage terminal, and a converter neutral point on said secondary side; and
two surge arresters respectively connected between one of said DC voltage terminals or a potential point having a comparable potential and said converter neutral point.
2. The device according to claim 1 , wherein said sub-modules at least partially form a half-bridge circuit.
3. The device according to claim 1 , wherein said sub-modules at least partially form a full-bridge circuit.
4. The device according to claim 1 , wherein said converter transformer has primary windings connected at a grounded neutral point.