Design And Analysis Of High Speed Permanent Magnet Synchronous Motor

High-speed motors have many advantages.The most promint features are high speed,high power density and relatively small volume,etc.And it can be directly connected to the load,eliminating the connection device and reducing costs.It can also reduce noise and improve the efficiency of transmission system.It is because of these characteristics,make them be suitable for high-speed metal cutting machines,machine tool spindle motors,some refrigeration systems,etc.Therefore,this paper mainly studies a high-speed permanent magnet synchronous motor with a rated power of 24 kW and a rated speed of 20000r/min,the main analysis includes electromagnetic design,rotor strength analysis,loss and temperature field calculation.The main research contents are as follows:Firstly,according to the characteristics of high-speed motor itself,the design of the stator and rotor is carried out,including the selection of the rotor structure,the selection of the inner and outer diameter of the stator,the selection of the length of the rotor core,the selection of the air gap length and the thickness of the sheath,and the matching of the slot,the choice,as well as the selection of materials for each component.The high-speed permanent magnet motor of 24 kW and 20000r/min is analyzed and studied by finite element software.The electromagnetic design of synchronous motor is carried out to determine the size each part of the motor,and the no-load characteristics and load characteristics of the motor are analyzed by finite element method to prove the accuracy of motor design.Secondly,the design of the rotor strength is analyzed for the motor.Due to the high speed of the high-speed motor itself,the rotor will bear considerable tensile stress during high speed operation.In order to ensure the safe and stable operation of high-speed permanent magnet motor,a kind of sheath should be adopted to protect the permanent magnet,and interference fit between the permanent magnet and the sheath is adopted.Most of the sheaths are made of carbon fibers or non-magnetic alloys,so that the permanent magnet will not be damaged when the motor is running,thus ensuring the stable operation of permanent magnet motor.Based on the theory of elastic mechanics and finite element contact theory,the three-dimensional model of the rotor of the motor is established.Then the finite element analysis of the rotor of high-speed permanentmagnet motor is carried out by ANSYS Workbench.The influences of different static interference,thickness of alloy sheath and temperature character on rotor strength are compared.Meanwhile,the strength of the model sheath and permanent magnet are calibrated,and the mechanical design rules of high speed permanent magnet motor rotor are summarized.The calculation method of rotor structure and strength has been applied to the prototype design of high-speed permanent magnet motor.In addition,the stator core loss of the motor is calculated by finite element method;the stator copper loss of the high-speed motor is calculated by formula method;at the same time,the three-dimensional model of the motor is established.and the eddy current loss of the permanent magnet and sheath of the high-speed motor is calculated by Ansoft finite element software.Finally,the motor is cooled by the water cooling method of the casing,and in this case,the temperature of each part of the motor is simulated by finite element method to ensure that the temperature values are within the ideal range.