Driving apparatus for electric motor

A driving apparatus for driving an electric motor, such as a synchronous motor or an induction motor, and more particularly to a driving apparatus which performs a vector control based on an output current of an inverter. The driving apparatus of the present invention includes an inverter, a current detector configured to detect an output current of the inverter, and a vector controller configured to transform the output current, detected by the current detector, into a torque current and a magnetization current and to control the torque current and the magnetization current. The vector controller includes a target-output-voltage determination section configured to determine a target output voltage from the torque current, the magnetization current, an angular velocity of the rotor, and motor constants, and a target-magnetization-current determination section configured to determine a magnetization-current command value based on a deviation between the torque-voltage command value and the target output voltage.