Motor control device and electric power steering device provided with same

A motor control device applied to a motor drive system in which power from a DC power supply is converted into three-phase AC power by an inverter and supplied to a brushless motor for calculating a voltage command output to the inverter by vector control, the motor control device comprising:

• a torque command/current command converter configured to convert an input torque command into a d-axis current command value and a q-axis current command value;
• a field-weakening controller configured to determine a d-axis current command correction value in a field-weakening control according to a modulation factor that correlates with a ratio of a voltage amplitude applied to an inverter to a voltage of a DC power supply;
• a d-axis current final value calculator configured to output a d-axis current command final value calculated using the d-axis current command value and the d-axis current command correction value;
• a current controller configured to perform a feedback control of the d-axis current command final value and the q-axis current command value;
• and
• a d-axis current adjuster configured to adjust the d-axis current command final value based on the q-axis current command value so as to suppress an influence of a frequency component of the q-axis current command value in a specific frequency band for which at least a lower limit frequency is determined.