Motor control device, electric power steering device, and vehicle

A motor control device, comprising:

• a motor electric angle initial value estimation unit that, when a motor electric angle detection unit, that detects a motor electric angle of a multi-phase electric motor that generates a steering assist force, is diagnosed as being abnormal in an initial diagnosis after a system restart, estimates an initial value of the motor electric angle on a basis of a response output of the multi-phase electric motor in response to input of a motor drive signal to the multi-phase electric motor;
• a motor electric angle estimation unit that calculates a motor electric angle estimation value θme according to a formula (1):
• θme=θos×RGr×P+θoff, wherein θos is an output shaft rotational angle detection value which is a steering angle detected by a steering angle detection unit, RGr is a deceleration ratio, P is a number of pole pairs, and θoff is an offset amount between an origin of the motor electric angle and a reference value of an output shaft rotation angle;
• a motor drive control unit that, when the motor electric angle detection unit is normal, drive-controls the multi-phase electric motor on a basis of the motor electric angle detected by the motor electric angle detection unit, and when the motor electric angle detection unit is diagnosed as being abnormal in the initial diagnosis after the system restart, drive-controls the multi-phase electric motor on a basis of the motor electric angle estimation value estimated by the motor electric angle estimation unit;
• wherein the motor electric angle initial value estimation unit estimates the initial value of the motor electric angle on a basis of a current;
• response at a time when a harmonic or pulse wave energization has been applied to the multi-phase electric motor;
• and
• a motor electric angle initial value correction unit that corrects the initial value of the motor electric angle on a basis of a current response at a time when a harmonic or pulse wave energization at such a level that magnetic saturation occurs has been applied to the multi-phase electric motor.