Design And Optimization On Slotless High-speed Permanent Magnet Brushless DC Motor

High-speed permanent magnet brushless DC motors have the advantages of high power density,high speed,small size,and short starting time,therefore,the application field is becoming more wide.However,low efficiency and high manufacturing cost are the key factors limiting its application scope in high-speed and small power permanent magnet brushless DC motor.Slotless permanent magnet motor not only has the characteristics of ordinary permanent magnet motor,such as good speed regulation performance,high reliability and no commutating spark,but also has the advantages of high efficiency,small torque ripple,low loss,convenient winding production,small volume,low cost,etc.,which can well solve the problems of high-speed medium and small permanent magnet brushless DC motor.Therefore,it is of great significance and value to study the slotless high speed permanent magnet brushless DC motor.Firstly,according to the given parameters,the body design of the slotless high-speed permanent magnet brushless DC motor was carried out.On the basis of determining the main size of the motor,the stator structure,rotor structure,permanent magnet structure and other parts of the motor were designed.In addition,the effects of different pole-slot fits and different magnetization methods of permanent magnets on the slotless high-speed permanent magnet motor were analyzed in this paper.Secondly,the electromagnetic performance of the designed motor was analyzed by finite element simulation.The rationality of the designed motor is verified by the simulation results of no-load and load conditions.At the same time,the core loss and torque fluctuation of slotless high speed permanent magnet brushless DC motor and ordinary high speed permanent magnet brushless DC motor were compared.Finally,in view of the shortcomings of long air gap,large flux leakage and low output torque of slot-less permanent magnet motor,a method to reduce the flux leakage and improve the torque of the motor via adding axially magnetized permanent magnets at both ends of the rotor permanent magnet was proposed.Based on the analysis of the characteristics of magnetic flux leakage at the end of the designed motor,the effects of reducing magnetic flux leakage at the end of the motor and improving the output torque of two different magnetizing methods of permanent magnets were compared through simulation.At the same time,in order to achieve the purpose of optimization,the model simulation of 6 groups of permanent magnets with different lengths was carried out.