【作者】 高鹏；

【导师】 王晓远；

【作者基本信息】 天津大学 ， 电机与电器， 2015， 博士

【摘要】 电动汽车是人类社会新时代中具备清洁环保、能量可高效利用、能源可再生和可持续的交通工具。电动汽车作为一种道路交通工具,主要依靠电力系统驱动,涉及多学科多方面的技术知识,内容广泛且复杂。现阶段电动汽车驱动系统发展的关键技术主要为能源技术和驱动技术,在电动汽车能源技术发展遇到瓶颈的时期,开发高性能的驱动系统尤其重要。随着国内外电动汽车驱动系统技术的不断发展,采用轮毂式电动机直驱的驱动系统受到了广泛关注。轮毂电机直接驱动系统具备机械结构简单、传动效率高、控制灵活、便于一体化设计等优点,成为电动汽车驱动系统技术发展的必然趋势。本文着重对轮毂电机驱动系统中的轮毂式电动机进行研究和分析。在轮毂电机驱动系统的一体化设计中,轮毂电机直接安装于车轮内部,势必会增大汽车的簧下质量,影响汽车的运行平顺性。所以,在轮毂电机的设计过程中,除了要考虑电动汽车驱动技术的一般需求,轮毂电机还应具有高功率密度和高转矩密度等特点。本文根据一般家用轿车乘用车的结构和运行性能需求,设计出了额定功率8.5kW,峰值功率20kW的轮毂电机样机。为了提高电机的力能指标和材料利用率,同时也为了提高电机的功率密度,样机设计为外转子式结构。由于汽车车轮内部空间有限,样机采用分数槽绕组结构。基于磁路法对电机的性能参数进行了计算,根据计算结果对样机进行了优化设计。提出了将进化策略应用于轮毂电机永磁体结构的优化设计,以电机永磁体的尺寸参数为优化变量,电机的性能参数为优化目标。基于建立的轮毂电机有限元分析模型,将电机结构参数的优化算法与有限元分析相结合,对永磁电机永磁体尺寸参数进行寻优计算,实现永磁电机多变量多目标的优化设计。引进了Halbach永磁体阵列结构。通过进化策略和有限元分析相结合的方式,实现了对Halbach永磁体阵列结构的优化设计,通过实验验证了有限元模型的正确性、进化策略的有效性和实用性。分别采用热网络法和有限元法对轮毂电机稳态温升进行计算,验证了外转子内定子结构轮毂电机存在的内部热量散热困难的问题。对轮毂电机温度场进行了分析,提出了油内冷轮毂电机冷却方案。基于传热学理论和有限元理论,分别建立了轮毂电机电磁场和温度场有限元分析模型,对采用自然冷却和油内冷冷却方式的轮毂电机进行三维磁热耦合仿真分析。磁热耦合分析结果和实验测量数据表明,油内冷冷却方式有利于降低轮毂电机的温升、减小轮毂电机内部各部件的温差;扩大轮毂电机的高效运行区域、提高最大运行效率;提高轮毂电机的转矩密度,同时功率密度也相应提高。更多还原

【Abstract】 Electric vehicle(EV) is the road vehicle in the new century. Compared to the traditional vehicle, electric vehicle has many advantages, including clean and green, energy-efficient, renewable and sustainable development. As the new type road vehicle with electric propulsion, it involves many subjects and a wide range of technical knowledge. At this stage energy technology and drive technology are the key issues of drive system development of EV. It is particularly important to develop high-performance drive system when there is a bottleneck in the development of energy technology. Along with the development of drive technology both in C hina and abroad, the direct drive system with in- wheel motor gets wide attention. It has the advantages of simple mechanical structure, high transmission efficiency, high control flexibility and easily integrate design. It is an inevitable trend of development. The in-wheel motor of drive system used in EV has been studied and analyzed emphatically in this paper.The in-wheel motor will be mounted inside the wheel. It increases the unsprung mass and hence deteriorates ride comfort and reduces the road holding capability of the automobile. In addition to meets the general need of the drive technology of EV, the in-wheel motor also need to meet high power density and high torque density.According to the structure size of automobile wheel hub and the running performance of automobile, an in-wheel motor is designed in this paper. The rated power of the in- wheel motor is 8.5 kW, the peak power is 20 kW. In order to improve the force index of the motor and the material utilization. The exterior rotor structure is chose. The stator winding is designed as fractional-slot concentrated winding to satisfy the space limitation of the wheel.The performance parameters of the motor prototype are calculated based on the magnetic circuit method. O n the basis of calculation results, the optimization design of the motor is carried out. The evolutionary strategy(ES) is proposed to optimize the permanent magnet shape. The structure parameter of the permanent magnet is set as the optimal variables and the performance parameters of the motor as the optimal objective during the optimization process. The finite element analysis(FEA) model of the in-wheel motor is also established in this paper. The optimal design of in- wheel motor with multivariable and multiobjective is achieved by ES and finite element method(FEM). It is also applied to optimize the in-wheel motor with Halbach permanent magnet array successfully.The accurate thermal analysis of in- wheel motor is quite important to its safety operation and performance improvement. The equivalent thermal network method and the FEM are used to calculate temperature rise of the in-wheel motor. The heat dissipation problem of in- wheel motor with exterior rotor and inner stator is validated. The calculate results also show that the two methods are adaptable and compatible to calculate the temperature field of motor. According to the structure of in-wheel motor used in EV, the inner-oil cooling method is proposed. The 3-D finite element analysis models were established for the in-wheel motor with natural cooling and inner-oil cooling. By comparing the calculation results with measurement results, the correctness of the FEA and the validity of inner-oil cooling method were verified. This is conducive to reduce temperature rise, improve running efficiency, improve the power density and the torque density of the in-wheel motor.更多还原