Electric motor control device

An electric motor control device mounted on a drive device including an electric motor, an inverter configured to drive the electric motor, and a power storage device configured to exchange power with the electric motor through the inverter, the electric motor control device comprising an electronic control unit configured to:

• perform switching control of a switching element of the inverter by switching between pulse width modulation control mode and square wave control mode according to a modulation degree, wherein the square wave control mode uses, when the number of revolutions of the electric motor is greater than or equal to a first predetermined number of revolutions which is greater than a first resonance region, a square wave pulse pattern in which a first half or a second half of one period becomes a square wave pulse, and uses, when the number of revolutions of the electric motor is less than the first predetermined number of revolutions which is greater than a first resonance region, a first switching pattern in which one or more slits are formed in a region where the square wave pulse is present and one or more short pulses, having the same width as the slits, are formed at the same time when the slits are formed, in a region where the square wave pulse is not present in the square wave pulse pattern, the first switching pattern curbing LC resonance in the first resonance region;
• and
• perform control of a first gradual variation in which widths of the slits and the short pulses of the first switching pattern gradually change to become small, when switching from the first switching pattern to the square wave pulse pattern.