Drive system

Electromagnetic noises that accompany the operation of a converter device are decreased in the case where a railroad vehicle runs in the vicinity of a stopping station. If the speed of the vehicle becomes equal to or less than a first reference speed, the carrier frequency of the converter device is changed from a first reference frequency to a second reference frequency, and if the speed of the vehicle becomes equal to or larger than a second reference speed, the carrier frequency of the converter device is changed from the second reference frequency to the first reference frequency.