Abstract: A brushless motor-generator has a stator with armature windings for polyphase operation and a rotor having at least one pair of permanent magnet poles. A controller varies the magnitude of the alternating-current voltage applied to the armature windings for controlling the operating motor power factor to permit the rotor magnetic field to operate at the optimum or at least at an improved torque angle with respect to the stator magnetic field in the motoring mode, with little or no torque pulsations at substantially all or at least most conditions of motor load.