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Scheme design decides about 70% – 80% of the product design cost, and is critical importance to the success of product design. In this paper, a theory of fuzzy comprehensive evaluation was proposed for the selection of several options based on value engineering and fuzzy mathematics. The index system for value evaluation of the product design scheme was constructed with the function analysis method. Then based on the fuzzy control concept, the fuzzy sets including the uniform index factors, the evaluation language and so on were established, and the memberships between the factor sets and the remark sets were described with the fuzzy triangle membership functions. The fuzzy relation matrixes of the function evaluation and value evaluation were established for the products at different layers from scheme layer to goal layer, then the vectors of fuzzy evaluations were solved for defuzzification and getting the sequence of the evaluation on multiple design schemes. The fuzzy comprehensive evaluation of the project value was carried out for the 4 examples: single screw pump, double suction twin screw pump, single suction twin screw pump, and variable lead twin screw pumps. The evaluation result could give the best selection of screw pump design schemes.

The friction and abrasion of the traditional single degree of freedom motor have an impact on the dynamic response of the system. This paper presents bearingless permanent magnet motor structure based on permanent magnetic bearing radial bearing and axial magnetic bearing, the overall structure of the motor is also introduced in the paper. Bearingless motor with permanent magnet bearing radial bearing and bearing axial electromagnetic bearing is designed and analyzed. Then set parameters of magnetic bearing structure according to the related data, and calculate related dimensions of magnetic bearing through theoretical calculation. Using ANSYS software to calculate the magnetic bearing part of the motor, and then do some structural optimization designs by analyzing the distribution of magnetic field, magnetic flux density and air gap magnetic field.

Magnetic levitation (no bearings) motor by using magnetic force to make rotor suspend and drive realize its high or ultra-high speed rotating. The stator’s structure of traditional no bearing magnetic levitation motor is double winding which is polar logarithmic difference 1 of 2 sets of winding (torque winding and suspension winding) and embedded in the stator. Using two inverter respectively for the two sets of winding to go into the same frequency current in order to realize the suspension of the rotor and motor’s driven, small carrying capacity of motor’s structure, controlling complex system. This paper based on the traditional motor technology puts forward a kind of arc principle and respectively decorates two arc motors in horizontal and vertical direction symmetric to rotor according to the electromagnetic bearing suspension technology that is constituted the arc magnetic levitation induction motor. Establishing air-gap transformation regular between rotor and stator (air-gap length) motor is under the effect of interference. Based on the electromagnetic theory establishing distribution regular of the air-gap magnetic induction intensity. Virtual displacement principle is used to establish electromagnetism mathematical model and motor electromagnetism levitation. By the finite element analysis carrying on simulation research to the magnetic induction intensity, electric magnetic levitation force and distribution features of electromagnetic torque and so on.