| Upscale electronic chips,large-scale integrated circuits,fine chemicals,pharmaceuticals,photovoltaic power generation and other fields require high-performance vacuum equipment,and the drive motor is the core power component of the vacuum pump.The axially segmented claw pole permanent magnet synchronous motor has the advantages of high torque density and high power density in terms of performance;In terms of cost,because of its special structure,the winding has no ends,which improves the utilization rate of copper,which is beneficial to reduce copper consumption and improve efficiency.In order to improve the sealing performance of the vacuum pump,the drive motor is moved into the vacuum pump to form a new pump-machine integrated structure;at the same time,some motor components,especially the rotor,are placed in a vacuum environment,and it is very difficult to dissipate heat.The heat dissipation effect of heat conduction and heat convection is sharply reduced,and heat radiation becomes the main or even the only way to dissipate heat.Reducing the rotor loss,that is,the heat source,is the key technical means to ensure the safety of the vacuum pump drive motor.The axially segmented claw pole permanent magnet synchronous motor has the characteristics of low rotor loss and is expected to become an upgraded version of the vacuum pump drive motor.For this purpose,three axially segmented claw pole permanent magnet synchronous motors for vacuum dry pumps with 1.5k W,9000r/min and different stator claw pole shapes were developed.Firstly,the vacuum pump driving motor and claw pole motor are introduced in detail.The structural characteristics and working principle of the axially segmented claw pole permanent magnet synchronous motor are analyzed.And the design methods and processes of the axially segmented claw pole motor are given.Secondly,three axially segmented claw pole permanent magnet synchronous motors with different knee structures are designed according to the performance index of a permanent magnet synchronous motor for driving a vacuum dry pump.The effects of root thickness,stator yoke thickness,claw tip length,claw tip thickness and claw pole angle on the motor torque and torque ripple are mainly studied.Based on this,the structure of the stator claw poles with three claw pole shapes: right-angled knee,rounded knee and obtuse-angled knee is optimized.The analysis results show that the increase of the thickness of the claw root can improve the motor torque;the length and thickness of the claw tip of the stator should be less than the maximum value,which is helpful to improve the motor torque and reduce the torque ripple;under the condition that the outer diameter of the stator remains unchanged,increasing the claw pole angle can increase the motor torque and reduce torque ripple,but an excessively high claw pole angle will increase the magnetic flux leakage between the claws,which will reduce the torque performance.And when the claw pole arc coefficient is equal to the permanent magnet pole arc coefficient,the motor torque value reaches maximum.Finally,the electromagnetic field and temperature field of the motors with three different knee structures are analyzed to verify the rationality of the motor design.The results show that the magnetic density distribution of the three motors is reasonable,and the air gap magnetic density of the three motors is similar;the rounded claw pole has the best torque performance,the right-angle claw pole has the highest no-load back EMF amplitude,and the obtuse claw pole has the smallest loss;the rotor temperature of the axially segmented claw pole permanent magnet motor is the lowest when it runs stably,and the rotor temperature meets the requirement of vacuum dry pump proves the feasibility of this motor as a drive motor for vacuum dry pump. |
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