Motor controller and power steering device

A motor control system for driving a motor including three or more phases n, the motor control system comprising:

• an inverter that drives the motor;
• an operation controller that controls the inverter according to a current command value;
• and
• a torque ripple compensation generator that adds a compensation value to compensate for a torque ripple in the motor to the current command value;
• wherein
• the operation controller uses, as the current command value, a q-axis current command value indicating a q-axis current in a rotational coordinate system of the motor, and also uses, as the current command value, at least temporarily a d-axis current command value indicating a d-axis current in the rotational coordinate system;
• and
• the torque ripple compensation generator calculates a phase difference of the compensation value with respect to the q-axis current command value according to an equation using the q-axis current command value and the d-axis current command value as variables.