To provide a motor drive control device that improves the resolution of current detection without using an external A-D converter and that increases output torque by reducing a current peak value at the time of a high load, and a motor-driven power steering device using the motor drive control device.
The motor drive control device is configured to calculate a current command value of sine-wave drive to a command value by a current command value calculation portion, to drive a motor by vector control to the current command value, to detect rotation angle and angular velocity of the motor and input them into the current command value calculation portion, and to feedback an actual current of the motor with a digital value. In this device, a superposition judgment portion, which outputs a superposition command signal when a load output of the motor exceeds a prescribed value, a third harmonic generation portion, which generates third harmonic when the superposition command signal is output, and a current command value correction portion, which superposes the third harmonic on the current command value to correct the current command value, are provided.
Sadayoshi Igarashi
Susumu Kitano