Patent ID: 8390223

Claim:
A control device that controls an electric motor drive device, which controls a DC/AC conversion section that converts a DC voltage into an AC voltage to supply the AC voltage to an AC electric motor using a vector control method, the control device comprising: a voltage control section that generates three-phase voltage command values from two-phase voltage command values and that generates a switching control signal configured to drive the AC electric motor, wherein a first voltage control section that derives a modulation rate representing a ratio of an effective value of the two-phase voltage command values to an actual DC voltage supplied to the DC/AC conversion section and a voltage command phase which is a phase angle between voltage vectors represented by the two-phase voltage command values, a second voltage control section that generates the three-phase voltage command values based on the modulation rate, the voltage command phase, and a magnetic pole position detecting a rotational angle of a rotator of the AC electric motor and that generates the switching control signal configured to drive the AC electric motor based on the three-phase voltage command values, and a computation cycle of the first voltage control section is set to be longer than a computation cycle of the second voltage control section.