mater and c manuf represent the effective material cost and the fabricating cost of the high efficient energy saving multiphase asynchronous motor respectively the effective material cost consist of the cost of iron copper or aluminum and insulating materials etc the fabricating cost is the other cost except the effective material cost during the motor production the proportional relation between effective material dosage and fabricating cost can be adjusted according to the actual situation 4 designating the level number and the corresponding values of the design variables for optimization building the controllable factor level table selecting an appropriate orthogonal table according to the number of the optimization variables and the level number of each variable building an inner orthogonal table for inner design 5 taking the effect of the motor 39 s production and processing level assembly technology working condition and environment internal structure degradation and operation wear into consideration the parameter errors resulting from the above factors are taken as the noise factors designating the level number of each noise factor and the corresponding value of each level building the noise factor level table selecting an appropriate orthogonal table according to the number of the noise factors and the level number of each factor building an outer orthogonal table for outer design 6 treating each output characteristic as u201c the small the better u201d characteristic respectively the noise factor is listed in the outer orthogonal table corresponding to each combination of the inner.