To enable the continuation or stop of operation without damage to an element of a converter by suppressing overcurrent when instantaneous interruption occurs in AC power supply and it is then recovered.

The converter control device 10 operates on a case-by-case basis. When an instantaneous interruption detection circuit 11 detects an occurrence of instantaneous interruption and a bus voltage 100% detection circuit 12 detects a bus voltage not higher than a threshold voltage, it turns off a main contactor 3 to stop the operation of a converter 5. When the instantaneous interruption detection circuit 11 detects the recovery of instantaneous interruption, it causes an auxiliary precharge circuit 40 to carry out precharging before it turns on the main contactor 3. When a bus voltage 90% detection circuit 13 detects a bus voltage not lower than the threshold voltage, it causes precharging to be completed, turns on the main contactor 3 to bring the converter 5 into operating state, and brings an inverter 7 into operating state.

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