Control system for electric motor

A control system for current supplied to an electric motor having a stationary member, a movable member and no mechanical commutator, so as to produce a desired torque at minimum motor excitation current, comprising:

• a. detector means coupled to the movable member for determining a position and velocity of that member relative to the stationary member and furnishing signals related thereto respectively:
• b. command means connected to receive the signals from the detector means, and providing a motor command signal therefrom, the command means including:
• (i) phase shift means which receive the position and velocity signals and a torque direction signal and determine a spatial relationship between the movable member and a resultant stationary member field that permits the motor to produce the desired torque with a minimum motor excitation current, and provides an orientation command signal;
• and
• (ii) commutator means coupled to the phase shift means and receiving the orientation command signal and a torque error signal, and producing therefrom the torque direction signal and a motor command signal;
• and
• c. generator means connected to the command means to receive the motor command signal, and connected to the stationary member of the motor to supply excitation current thereto in response to the motor command signal.