Design And Research On Noise Analysis Of Permanent Magnet Brushless DC Motor

Permanent magnet brushless dc motor (PMBLDCM) with electronic commutating device take the place of mechanical commutation which solve the problem of noise and using life that brought with by brush and commutator. Retaining the broad and smooth speed regulating performance of the ordinary dc motor, PMBLDCM has the merits such as small volume, light weight, simple structure, reliable operation, high efficiency, high power density, flexible shapes and demensions, etc. The excellent speed regulating performance of PMBLDCM can make it obtain higher efficiency in larger speed range. Based on analyzing the trait of the fan and pump loads, this paper bring in the PMBLDCM system. Main content of this paper includes the following points:Firstly, according to the working trait of the PMBLDCM, the electromagnetic noise of PMBLDCM is calculated and analyzed by ANSYS software, and the accuracy and feasibility of the calculation method is verified by testing results. The effect of structure parameters on the electromagnetic noise of PMBLDCM is analyzed. The parameters include different pole-slot matches, pole arc coefficient, the magnetizing direction length of permanent magnet, the shape of permanent magnet, the width of stator rabbet, the height of stator rabbet and the angle of stator slot shoulder.Secondly, after analyzing the trait of PMBLDCM and factors affecting properties, a PMBLDCM, whose power rating is 5.5kW, rated speed is 3000r/min, main working speed are 3000r/min, 2400r/min and 1800r/min is developed and designed. According to the working trait of this type motor, the basic parameters of motor design are chosen, the design of the motor with high efficiency is studied from the following aspects, pole-slot matches, the ratio of stator inner and outer diameter, the length of air gap and stator slot area. Through comparison and optimization of the schemes, the final design scheme of the prototype is obtained.Finally, the prototype satisfied the requirements is manufactured, the efficiency and noise experiments with fan and pump loads are carried out on the prototype, which examined and verified the feasibility of the design scheme. Compare the efficiency of prototype system with that of variable frequency adjustable speed system with asynchronous motor, and the efficiency of motor ontology in each system is contrasted.