Abstract: A three-phase power factor control system for an AC induction motor (10) monitors the power factor of a first-phase motor winding and produces a rectangular-wave pulse power-factor signal (f) which is used to directly control the duration of "on" time of each cycle of input power to the first-phase winding and to indirectly control the "on" time of each cycle of input power to second- and third-phase windings. To provide a signal for controlling the power to second- and third-phase windings the power-factor pulse signal is synchronized with a square-wave oscillator (30) whose frequency is three times that the power-factor pulse signal. Each second and third positive pulse (38 and 40) of the square-wave oscillator (30) is used to control the "on" time of each cycle of input power to the second- and third-phase windings.