Optimum design of shaded-pole motors by means of 2-phase symmetrical components

By application of the 2-phase symmetrical components to the shaded-pole motor, which is regarded as an asymmetrical induction motor, equations for calculation of principal characteristics, such as steady-state torque and double-frequency alternating torque, are derived. Based on these equations, the speed characteristics of the double-frequency alternating torque, effects of the parameters on steady-state torque curves and maximum efficiency are discussed. Parameters for many examples of machines are investigated, and it is shown that their parameter ratios are within certain ranges. Optimum values of parameter ratios are obtained by taking into account efficiency, steady-state torque, alternating torque etc. The limit of the shaded-pole motor, i.e. the best possible performance, is discussed. Experimental confirmation of the theory is given.