CONTROLLER FOR PERMANENT MAGNET SYNCHRONOUS MOTOR

摘要

PURPOSE:To prevent demagnetization of a permanent magnet by supplying a current to an armature coil corresponding to a rotational position so that the direction of induced magnetic field may be approximately perpendicular to that of magnetic field within the permanent magnet. CONSTITUTION:Pulses generated by a pulse generator 10 as it rotates by a unit angle are input into a pulse counter 11 and a vector oscillator 16. The pulse counter 11 outputs a signal NM proportional to the rotational speed of a permanent magnet 1 on the basis of the pulses. On the other hand, the angle of rotation from a predetermined reference position of the permanent magnet 1 is always measured by the vector oscillator 16 and multiplied by a deviated vector IIS by a vector multiplier 17. From the result of the multiplication, the direction of magnetic field generated in a permanent magnet synchronous motor M is so controlled to be approximately perpendicular to the direction of magnetic field within the permanent magnet 1.