Abstract: A pulse voltage generator calculates a corrected pulse voltage application time. The pulse voltage generator also outputs, for the duration of the corrected pulse voltage application time, a voltage vector closest to a rotor phase from among twelve voltage vectors as a voltage vector command. A current detector detects three-phase output currents of a power converter, which are obtained when first to sixth switching elements of the power converter are turned on or off on the basis of the voltage vector command. A three-phase/two-phase converter converts the three-phase output currents to two-phase output currents to output d-axis current. When the d-axis current after the corrected pulse voltage application time has elapsed becomes less than or equal to a demagnetization determination threshold value, a demagnetization determiner determines that demagnetization occurs in a permanent magnet of a rotor of a motor.

Abstract: A pulse voltage generator calculates a corrected pulse voltage application time. The pulse voltage generator also outputs, for the duration of the corrected pulse voltage application time, a voltage vector closest to a rotor phase from among twelve voltage vectors as a voltage vector command. A current detector detects three-phase output currents of a power converter, which are obtained when first to sixth switching elements of the power converter are turned on or off on the basis of the voltage vector command. A three-phase/two-phase converter converts the three-phase output currents to two-phase output currents to output d-axis current. When the d-axis current after the corrected pulse voltage application time has elapsed becomes less than or equal to a demagnetization determination threshold value, a demagnetization determiner determines that demagnetization occurs in a permanent magnet of a rotor of a motor.