PURPOSE: To simultaneously adjust a bias current flowing in two control coils of a revolving shaft by differentially adding, subtracting and exciting through the addition and subtraction of one bias command voltage based on signals of a position sensor.
CONSTITUTION: Displacement signals of a position sensor 3 detecting shift in a rotor 2 are phase-compensated with a control circuit 4. A bias balance command voltage VO is added, and subtraction is made from a bias command voltage VB by No.1 differential type addition circuit 9a, and a control coil 6a is excited. The output of No.1 differential type addition circuit 9a is subtracted from a value twice the bias command voltage by No.2 differential type addition circuit 9b, then rectified and a control coil 6b is excited. Bias current flowing in two control coils can be adjusted simultaneously and easily by changing one bias command voltage, with the adoption of the device.
MATSUSHITA OSAMI
YONEYAMA MITSUO
SAITOU IKUHIRO
INOUE TOMOAKI
