Abstract: An improved motor controller is intended for use with an induction motor and has a control loop which includes an auxiliary winding, a capacitor and a saturable reactor. The auxiliary winding is electro-magnetically coupled to the stator winding in a manner such that the capacitive reactance of the control loop is effectively in parallel with the magnetizing reactance and the rotor leakage reactance of the motor. The control loop is devoid of any direct electrical connection to the motor.By varying the magnitude of current in its D-C control winding, the inductance of the reactor is adjusted so that the capacitive reactance of the control loop, as electro-magnetically reflected into the motor, is generally in resonance with the parallel combination of the magnetizing reactance and the rotor leakage reactance.