Patent ID: 7728536

Claim:
A current control method for a servomotor, the servomotor comprising: an armature having armature windings of multiple phases; and a field, the servomotor having such a structure that: armature currents are supplied to the armature windings having the respective multiple phases to generate armature magnetic flux; and the armature and the field are relatively rotated with each other based on an interaction between the armature magnetic flux and field flux produced by the field to generate rotation force, the current control method comprising: supplying a negative d-axis current Id to the armature to which a dq conversion has been performed while a d-axis direction is a direction of the field flux to prevent an occurrence of a voltage saturation in the servomotor, wherein under a condition that a relative rotational speed of the armature and the field is constant, the d-axis current Id in a negative direction is related to a magnitude |Iq| of the q-axis current.