| Low-speed high-torque synchronous motor(LSHTSM)has a very broad application prospect in coal transmission,aerospace,oil mining,wind power generation,elevator traction and other fields,and it is one of the most key components of low-speed transmission systems.In order to make full use of the cavity space of the conventional LSHTSM and improve the torque density,the double-stator structure is the current development trend of LSHTSM.In addition,in order to effectively reduce motor costs while improving motor output performance and the material utilization ratio,the research on novel rotor structures is also one of the current research hotspots of low speed and high torque motors.In view of this,with the financial support of the National Natural Science Foundation of China,this paper takes the permanent magnet/reluctance hybrid rotor double-stator LSHTSM as the research object,a more in-depth and comprehensive research work has been carried out on its electromagnetic and structural design,temperature field analysis and cooling system design,optimization design method and experimental research.It lays a foundation for the application and popularization of this new structure motor.The main contents of this dissertation include the following aspects:(1)Due to the complex operating principle and structure of hybrid rotor double-stator LSHTSMs,the electromagnetic and structural design methods of conventional LSHTSMs are no longer applicable.Therefore,taking into account the different operating characteristics of the inner and outer unit motors and the influence of the multipole structure on the operating performance of the reluctance motor,the power distribution relationship between the inner and outer unit motors of this type of motor was derived.On the basis of the standard motor and related design requirements,the method of determining the main size of the motor is given,the influence of the main design parameters of the motor on the operation performance is explored,and the realization method of the output performance consistency of the inner and outer unit motor is studied.Based on the relevant research results,the electromagnetic design methods and principles of this new type of motor are summarized.In addition,based on the comparative analysis of the advantages and disadvantages of the commonly used double-stator motor topology,a double-end support topology which can ensure the safe and stable operation of the motor is proposed,and the mechanical structure and transmission system of the motor are designed.Based on the related design methods,a 46.7k W and 90r/min hybrid rotor double-stator LSHTSM is designed,and its electromagnetic characteristics and mechanical properties are analyzed.The results verify the correctness and effectiveness of the proposed electromagnetic and structural design methods.(2)In order to calculate the temperature of each part of the motor quickly and accurately,to better guide the design of the electromagnetism,structure and cooling system,an accurate thermal network temperature calculation model of the whole structure is established.The model for calculating the thermal resistance of each part of the motor considering various heat transfer modes is derived,and on this basis,the steady-state temperature of each part of the motor is calculated.Compared with the finite element calculation results,the effectiveness and feasibility of the proposed thermal network temperature calculation model are verified.In order to solve the problem of serious heating and difficult heat dissipation,based on the characteristics of temperature distribution,a cooling system with inner and outer water cooling is proposed.The influence of water channel structure,number of water channels(water pipes),cross-sectional parameters of water channels(water pipes),and cooling water flow rate on the cooling effect of the motor are revealed.On this basis,the design scheme of the cooling system is determined,and the cooling effect is simulated and analyzed.The results show that the proposed cooling system can effectively reduce the temperature and ensure the safe and reliable operation of the motor.(3)Aiming at the problem of multiple design parameters of hybrid rotor double-stator LSHTSMs with strong interaction effects,which increases the difficulty of optimal design,a multi-objective optimization design method based on surrogate model is proposed.In order to explore the mapping relationship between optimization variables and optimization objectives,the sensitivity of optimization variables is analyzed by the combination of Latin hypercube test design and analysis of variance,and based on the results of sensitivity analysis,a high-precision surrogate model of motor optimization objective is constructed by using dynamic modeling method.In addition,in order to improve the optimization accuracy and efficiency and shorten the optimization period,an optimization algorithm based on sequential subspace and pattern search algorithm is proposed,and the motor is optimized based on the surrogate model.The analysis results show that the optimized design scheme can effectively improve the motor output torque and reduce the torque ripple on the premise that the cost is basically unchanged.(4)To verify the correctness,effectiveness,and feasibility of theoretical analysis and research methods,an experimental prototype of a 46.7k W,90r/min permanent magnet/reluctance hybrid rotor double-stator LSHTSM is designed and developed.The experimental test platform of the prototype is set up,and the hardware design and software debugging of the controller of this kind of special motor are carried out,and the control strategies suitable for the different operation characteristics of the inner and outer unit motors are adopted.The performance of the prototype under different operating conditions is studied experimentally.Through the experimental study of no-load,load,temperature rise and so on,it is verified that the electromagnetic and structural design,temperature calculation,cooling system design and optimization design methods proposed in this paper for back-to-back permanent magnet/reluctance hybrid rotor double-stator LSHTSM are correct,effective and feasible. |
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