A control unit is configured to generate a first switching signal based on a voltage command value and a first carrier and a second switching signal based on the voltage command value and a second different carrier, and a characteristic calculation unit estimates and calculates at least one of a resistance value of an electric motor and a dead time error, which is the difference between an effective value of a dead time and a set value of the dead time, based on a first operating characteristic of a power conversion unit obtained when switching elements are driven with the first switching signal and a second operating characteristic of the power conversion unit obtained when the switching elements are driven with the second switching signal. The resistance value of the electric motor and the dead time error can be quickly calculated and estimated by a common structure.