CONTROL DEVICE FOR RAILWAY VEHICLES AND DISCONNECTION DETERMINATION METHOD

A control device includes a changing rate calculator, a first threshold calculator, and a separation determiner. The control device determines whether a current collector is separate from a power line, in a power conversion system in which a power converter converts power supplied from the current collector to the primary side of the power converter into alternating-current (AC) power and supplies the AC power to a motor connected to the secondary side of the power converter. The changing rate calculator calculates a changing rate of the voltage at the primary side of the power converter. The first threshold calculator calculates a first threshold having the absolute value positively correlated with an output power from the power converter. The separation determiner compares the changing rate with the first threshold and determines whether the current collector is separate from the power line.