Study Of Double Stator Permanent Magnet Brushless DC Motor For Deepwater Propulsion

As human exploration of deep sea environment and resources accelerating, thehigh-performance underwater robot and manned submersible underwater equipmentrequirements is becoming increasingly important. As these devices in deep-seaenvironment mainly driven by electric source with deep-sea propulsion motor, whichdirectly affect the flexibility and handling of these equipments and plays a vital role in theunderwater task. In recent years, high-performance underwater propeller mainly usepermanent magnet brushless dc motors because its simple structure, high power density,etc. As double stator permanent magnet motor not only has the advantages of the commonsingle stator permanent magnet motor, but also has low rotor inertia, good dynamicperformance and can fulfill the technical requirements of deep-sea propulsion motor. Onthe basis of the characteristics of the underwater motor, the key problems ofelectromagnetic design of underwater double stator permanent magnet brushless dc motorare studied, and choosing the proper design scheme by comparing motor weight andvolume in different design scheme.According to the operation principle of the permanent magnet brushless dc motor,combined with double stator permanent magnet brushless dc motor magnetic circuitstructure, the electromagnetic relation and so on, this paper briefly analyzed of theoperation principle of double stator permanent magnet brushless dc motor and the spatialdistribution law of inner and outer stator winding, analyzed the of winding’s influence toback EMF and deduced calculation method of winding coefficient. Considering the deepsea working environment, according to the general design characteristics of the underwatermotor, the key design problems of underwater double stator permanent magnet brushlessdc motor are illustrated, such as the calculation method of main dimensions, the selectionof electromagnetic load and the structure characters of stator and rotor. Adopt the methodof "field and circuit", using the circuit program to complete the motor electromagneticdesign firstly and come out with electromagnetic design parameters, then built finite element models of double stator permanent magnet motor simulation software Ansoft withthese parameters, fixed the correlation coefficient of circuit program according to theresults of simulation, analyzed and simulated the motor’s performances such as coggingtorque and unload performance and so on.The correctness of the design method is verified by the analysis of a variety of designscheme, error within the acceptable range. According to the design, some important datasuch as electromagnetic load, the length to diameter ratio was summarized, to which isimportant for the follow-up work.