| With the rapid development of science and technology and the industry,all walks of life put forward more stringent requirements for motors.Power density has become an important index in motor design.High power density motor has attracted more and more attention from researchers and manufacturers because of its small size,light weight and high efficiency.However,by summarizing the research of high power density motors,it can be seen that there are still some problems in the development of high power density motors:(1)High power density motors are generally realized by high voltage or high speed methods,and there are few studies on low voltage and low speed high power density motors;(2)At present,the research mainly focuses on how to improve the power density of the motor,while the research on the influence of the method of improving the power density on the working performance of the motor is rarely involved.(3)In addition,the cooling mode of high power density motors is mostly liquid cooling mode,while the air cooling mode of high power density motors and the internal fluid of motors are seldom studied.Therefore,aiming at the above problems of high power density motors,in order to effectively improve the power density of conventional motors and expand their application scope in some special occasions,this thesis studies the related problems of improving the power density of conventional induction motors.Firstly,according to the complex coupling characteristics of electromagnetic parameters of high power density induction motor,the equivalent magnetic circuit method is used to compare and analyze the influences of the number of rotor slots,axial length of stator and rotor,air gap length,rotor bar material,rotor end ring material and motor heat dissipation mode on the electromagnetic performance,starting performance and torque output capability of the motor,and the selection principle of the above design parameters is determined.According to the determined design parameters,the two-dimensional finite element calculation model of induction motor is established.Based on the electromagnetic field theory,the performance of the motor is calculated by finite element software.The calculation results are compared with those calculated by the equivalent magnetic circuit method,which confirms the accuracy of the calculation and provides an effective reference for the design of high power density induction motor.Secondly,according to the running characteristics of the induction motor,the loss characteristics of the induction motor are analyzed,and the loss of each part of the induction motor is obtained.The stator core loss is studied by using the stator core layered model.Compared with the results calculated by the equivalent magnetic circuit method,it can be seen that the core loss calculated by using the stator layered model is more accurate.In addition,according to the loss calculation results,based on the theory of equivalent thermal network method,the motor thermal calculation model is established by using Motor-CAD software,and the temperature distribution law of high power density induction motor is obtained by considering the assembly clearance and other parameters,and the relationship between the heat dissipation parameters of motor housing and the motor temperature distribution is determined,which is helpful to guide the design of the cooling system of high power density induction motor.Finally,based on computational fluid dynamics,the cooling system of high power density induction motor is designed and studied.The relationship between axial ventilation holes in stator and rotor cores and electromagnetic performance and loss characteristics of motor is revealed.The influence laws of different aperture,hole’s spacing and hole’s number on electromagnetic field,fluid field and temperature field of motor are summarized.The rationality of the design of high power density induction motor is verified. |
