Patent ID: 7078839

Claim:
A self-bearing step motor system, comprising: a self-bearing step motor including a rotor having a plurality of rotor teeth, a stator having a plurality of stator teeth, a plurality of separate windings wound respectively around the plurality of stator teeth, and a plurality of sensors for measuring geometrical deviation of the rotor, the plurality of sensors includes a horizontal sensor for measuring a horizontal deviation of the rotor and a vertical sensor for measuring a vertical deviation of the rotor; and a controller which transforms a torque current for causing the rotor to rotate and control currents for performing a bearing function of supporting the rotor into predetermined supply currents capable of generating magnetic force for allowing the rotor to be supported while causing the rotor to rotate in accordance with outputs of the sensors which are fed back to the controller and position angles of the plurality of windings, and simultaneously distributes the supply currents among the plurality of windings grouped so that same phase currents can be supplied thereto, the controller comprising: a motor controller for outputting the predetermined torque current: a plurality of bearing controllers for outputting the control currents based on the outputs of the plurality of sensors fed back thereto, the plurality of bearing controllers include a horizontal bearing controller for outputting a horizontal control current based on an output of the horizontal sensor which is fed back to the horizontal bearing controller and a vertical bearing controller for outputting a vertical control current based on an output of the vertical bearing sensor which is fed back to the vertical bearing controller; and a current regulator for generating the supply currents by adding up the predetermined torque current and the control currents adjusted in accordance with the position angles of the respective windings and for distributing the supply currents among the plurality of the windings grouped so that the same phase currents can be supplied thereto, the supply currents obtained by multiplying the horizontal control current by a cosine value of the position angle of each winding, multiplying the vertical control current by a sine value of the position angle of each winding, and adding the two multiplied values to the output of the motor controller.