Patent ID: 8183874
Filing Date: 2012-05-22
Classification: G01R,H02M

Abstract:
1. A device for converting an electrical current, the device comprising: at least one phase module each 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; each said at least one phase module branch having a series circuit including submodules each having a capacitor and at least one power semiconductor; and a capacitor diagnosis device for a time-dependent determination of a capacitance of said capacitor of each of said submodules; said capacitor diagnosis device including, for each said at least one phase module, a branch current sensor for detecting a phase module branch current flowing in a respective phase module, a submodule sensor for each of said submodules for detecting a capacitor voltage dropped across said capacitor of a respective submodule, a device for detecting switching states of said at least one power semiconductor of said respective submodule, and an evaluation unit determining said capacitance of said capacitors of each said at least one phase module in a manner dependent on a respectively measured branch current, said switching states of said at least one power semiconductor and a respective capacitor voltage.