| CPC H02M 7/487 (2013.01) [H02M 1/32 (2013.01)] | 17 Claims |
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1. A computer-implemented method for operating a multi-level bridge power converter of an electrical power system connected to a power grid, the power converter comprising a first converter and a second converter coupled via a DC link, the method comprising:
arranging a plurality of switching devices having at least four inner switching devices and at least two outer switching devices in an active neutral point clamped topology, wherein the plurality of switching devices comprises, at least, a plurality of insulated gate bipolar transistors (IGBTs), the plurality of IGBTs comprising a first IGBT, a second IGBT, a third IGBT, a fourth IGBT, a fifth IGBT, and a sixth IGBT, and wherein the second IGBT, the third IGBT, the fifth IGBT, and the sixth IGBT are the at least four inner switching devices, and the first IGBT and the fourth IGBT are the at least two outer switching devices;
determining whether any of the plurality of switching devices is experiencing a failure condition by implementing a failure detection algorithm, the failure detection algorithm comprising:
generating a blocking state logic signal by comparing a switching device voltage and a threshold reference voltage for each of the plurality of switching devices;
determining an expected voltage blocking state for each of the plurality of switching devices based on gate drive signals of the plurality of switching devices and an output current direction; and
detecting whether a failure condition is present in any of the plurality of switching devices based on the blocking state logic signals and the expected voltage blocking states of the plurality of switching devices,
wherein the failure detection algorithm detects the failure condition in the first IGBT when an expected output voltage is not positive and the blocking state logic signal for the first IGBT is low.
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