CONTROLLER FOR AC ELECTRIC TRAIN

In a controller for an AC electric train capable of power running and regenerative running, and capable of detecting a power failure in an AC overhead wire for supplying AC electric power, a power failure in the AC overhead wire is swiftly and reliably detected. A power failure detector 14 provided in an electric-train control unit 8 includes a specific-frequency-signal calculating unit 16 that extracts a current component corresponding to a specific-frequency set value 26 from a main-transformer output-current detection signal 7 and outputs an extracted signal as a specific-frequency current signal 18, a subtracter 19 that subtracts the main-transformer output-current detection signal 7 from the specific-frequency current signal 18 and outputs a result of the subtraction as a current deviation 20, and a power-failure detecting unit 23 that compares the current deviation 20 with a predetermined power-failure-detection set value 22, and outputs a power-failure detection signal 15 when the current deviation 20 is greater than the power-failure-detection set value 22.