An Adjustable, Constant-Torque, Alternating-Current Motor

A single-phase, alternating current motor system is presented wherein the motor components form part of the control system to provide constant-torque regardless of speed changes and also provide a means for adjusting the magnitude of torque over a wide range of values--each adjustment resulting in a fixed torque for all of its associated speeds. This is accomplished by maintaining a constant field flux for all operating speeds and by maintaining an armature current having a component that is in time phase with the field flux. This component of the armature current is constant for each adjustment thereby providing a constant torque. The armature current is obtained by connecting one side of the armature circuit to a mid tap of the motor field winding and the other side to the junction of an inductor and a capacitor connected in series to the same voltage that supplies the field winding. Control of the torque of the motor is achieved by adjustment of the magnitude of the ohmic values, and the ratio of the capacitance reactance to the inductive reactance.