Efficiency-optimal operating conditions for single-phase induction motors

The double-revolving field model is used to determine theoretically efficiencyoptimal operating conditions for single-phase induction motors equipped with an auxiliary winding. The algorithm developed determines the optimal values of main winding current, auxiliary winding current and stator frequency for any desired combination of torque and rotor speed within the motor's ratings. Computer simulations are presented to validate theoretical results and relate optimal terminal voltages to computed winding currents. Experimental measurements made on a 2 pole, 1 hp, 230V submersible motor are compared with computer simulations. These measurements reveal that while it is most important to control core losses by matching the V/Hz ratio to the load, it is possible to make further efficiency improvements by exciting the auxiliary winding.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat