Patent ID: 7710066

Claim:
A motor control device, wherein the motor control device controls a motor built with a rotor having a permanent magnet and a stator having an armature winding, wherein, let an axis parallel to a magnetic flux produced by the permanent magnet be called a d-axis, then the motor control device comprises: a magnetic flux controller that derives, as a specified excitation current value, a specified current value corresponding to a d-axis component of a current passing through the armature winding; and a current controller that controls, based on the specified excitation current value, the current passing through the armature winding, the magnetic flux controller makes the specified excitation current value vary periodically, based on an estimated or detected rotor position, in a current range in which the magnetic flux is weakened, and changes the specified excitation current value according to a rotation speed of the rotor, wherein the specified excitation current value is varied at a speed k 1 times of the rotation speed of the rotor, and wherein k 1 is a natural number.