Control device for detecting disconnection

A control device comprising:

• a power converter that converts input power and drives an AC motor by turning a switching element on and off;
• a current detector that detects a current that the power converter outputs to the AC motor;
• a voltage controller that generates voltage command values to use for control of the power converter, on the basis of a drive command that commands rotating operation of the AC motor, and the current detected by the current detector;
• a disconnection detector that acquires an angular velocity of the AC motor, and determines that a disconnection between the power converter and the AC motor has occurred if a state in which, during a period from when the AC motor starts up until an absolute value of a resultant vector of the voltage command values reaches a value determined according to a maximum value of voltage that the power converter is able to output, the absolute value is not in a predetermined range continues for a predetermined time or longer, the predetermined range being a function of the angular velocity, an upper limit value of the predetermined range being a value obtained by multiplying, with a predetermined value, the absolute value when the AC motor is driven while in a state in which a disconnection between the power converter and the AC motor has not occurred;
• and
• a gate controller that outputs a gate command for controlling the turning on and off of the switching element provided in the power converter, on the basis of the voltage command values and a determination by the disconnection detector that a disconnection between the power converter and the AC motor has occurred.