Abstract: A motor control system for a plastic forming machine such as an injection molding machine is disclosed including an interface circuit and a phase inverter for sensing the individual operation steps of the molding machine, producing a time stream of voltage levels, each of which are representative of the least amount of power required by the molding machine to perform machine functions during such operation steps, and for varying the speed of the motor in response to such voltage levels during each of such operation steps so as to reduce the amount of electrical power required by such machine during its cycle period.