Patent ID: 7583048

Claim:
A controller for a motor adapted to control an operation of a permanent magnet field type rotary motor having a first rotor and a second rotor, which have a plurality of fields produced by permanent magnets and which are disposed around a rotating shaft, by carrying out field control as a result of changing a rotor phase difference, which is a phase difference between the first rotor and the second rotor, the controller comprising: a rotor position detecting means for detecting a position of the first rotor; an energization controlling means for carrying out energization control of the motor by converting the motor into an equivalent circuit based on a two-phase DC rotating coordinate system composed of a d-axis in the direction of a magnetic flux of a field of the motor and a q-axis, which is orthogonal to the d-axis, on the basis of a position of the first rotor, and by controlling the amount of energization of an armature on the d-axis and the amount of energization of an armature on the q-axis; a field weakening current command value determining means for determining a field weakening current command value, which indicates the amount of energization of the armature on the d-axis that is required for obtaining a predetermined field weakening effect; a rotor phase difference command value determining means for determining a command value of the rotor phase difference on the basis of the field weakening current command value; and a rotor phase difference changing means for changing the rotor phase difference on the basis of the rotor phase difference command value.