CONTROL DEVICE FOR MOTOR DRIVE SYSTEM AND VEHICLE HAVING SAME

A control device (200) for a motor drive system (100) including an AC motor (MG1) having a magnet in a rotor, a converter (120), and an inverter (130) generates a step-up command value for the converter (120) based on a torque command value for the AC motor (MG1). The control device (200) determines whether or not to carry out field-weakening control for increasing a current in a direction weakening force of a magnet that is supplied from the inverter (130) to the AC motor (MG1), based on the step-up command value and a state of drive of the AC motor (MG1). When field-weakening control should be carried out and when an absolute value of the torque command value is smaller than a threshold value, the control device (200) further increases the generated step-up command value. By doing so, an amount of a field-weakening current can be decreased and therefore efficiency of the motor drive system (100) can be improved.