Patent ID: 7960940

Claim:
A motor control device for controlling a d-axis current and a q-axis current on dq coordinates to control a motor, comprising: a q-axis current command value setting unit which sets a q-axis current command value; an upper limit/lower limit setting unit which sets an upper limit and a lower limit of the q-axis current; a comparing unit which compares the q-axis current command value set by the q-axis current command value setting unit and the upper limit and the lower limit set by the upper limit/lower limit setting unit; a q-axis current command value limiting unit which puts a limit on the q-axis current command value in accordance with a comparison result by the comparing unit; and a d-axis current command value setting unit which sets a d-axis current command value, on the basis of the q-axis current command value which is limited by the q-axis current command value limiting unit, wherein the upper limit/lower limit setting unit sets the upper limit and the lower limit in accordance with a rotational angular velocity of the motor, wherein the upper limit/lower limit setting unit determines the upper limit so as to satisfy the following Expression (A), and determines the lower limit so as to satisfy the following Expression (B); wherein: i qa_up ⁢ ⁢ lim ≤ - E - E 2 - DF D ( A ) i qa_down ⁢ ⁢ lim = - E + E 2 - DF D ⁢ ⁢ D = R 2 ⁡ ( L d - L q ) 2 ⁢ ω 2 - ( R 2 + L d 2 ⁢ ω 2 ) ⁢ ( R 2 + L q 2 ⁢ ω 2 ) , ⁢ E = R ⁡ ( L d - L q ) ⁢ L d ⁢ φω 3 - ( R 2 + L d 2 ⁢ ω 2 ) ⁢ R ⁢ ⁢ φω , ⁢ and ⁢ ⁢ F = - R 2 ⁢ φ 2 ⁢ ω 2 + ( R 2 + L d 2 ⁢ ω 2 ) ⁢ V lim 2 , ( B ) i qa — uplim is a q-axis current upper limit, i qa — downlim is a q-axis current lower limit, R is a stator winding resistance of the motor, φ is a magnetic flux on dq coordinates calculated from the interlinking magnetic flux of a stator caused by a field, ω is the rotational angular velocity at an electric angle of the motor, L d is d-axis inductance, L q is q-axis inductance, and V lim is a limit voltage in the dq coordinates where sinusoidal driving is allowed.