STABLE VARIABLE SPEED A.C. MOTOR DRIVE

摘要

For use with an adjustable speed a-c electric motor having a stator adapted to be coupled to a source of variable frequency excitation and a rotor in which torque is developed when the motor is excited, the strength of said torque being dependent on interacting current and flux in the motor, a scheme is provided that comprises means for deriving an angle feedback signal representative of the actual phase angle between the aforesaid current and flux and means responsive to said angle feedback signal for controlling the source of variable frequency excitation so as to control the frequency of stator excitation as a function of the angle feedback signal.