Patent ID: 8738208

Claim:
A propulsion control apparatus comprising: a converter for converting AC into DC to output; an inverter for converting the DC outputted from the converter into AC to supply to a motor, by using a VVVF control method when vehicle speed is not higher than a VVVF limited speed and a CVVF control method when the vehicle speed is higher than the VVVF limited speed; a filter capacitor provided at an intermediate link connection between the converter and the inverter; an auxiliary power supply, connected to the intermediate link connection, cooled by a self ventilation system; and a converter control unit, into which information of vehicle speed is inputted, for decreasing, based on the information, voltage at the intermediate link connection to a value at which temperature increase of the auxiliary power supply is within a limit, when vehicle speed indicated by the information of the vehicle speed is not higher than a predetermined speed which is lower than the VVVF limited speed and lower than a lower limit of a vehicle-speed range where input current into the converter is constant.