紧凑型高效高压感应电机起动过程电磁热耦合研究

发布时间：2018-09-06 07:28

【摘要】：随着电机领域相关技术的提高，高效高功率密度电机成为发展趋势。YJKK系列紧凑型高压电机是我国电机行业的新生产品，比原YKK系列电机中心高平均降低两个等级，体积的减小使表面散热面积减小，同时功率密度和电压等级的增加，使得人们对其起动特性及温升情况尤为关心。电机负载起动时，起动时间长，起动电流会使绕组温度迅速升高，较大负载可能导致电机不能正常起动。而起动过程定、转子阻抗及起动电流是判断绕组温升的重要依据；起动特性(电流-转速、转矩-转速)是衡量感应电机起动运行性能、判断电机能否正常起动的重要指标；用户需要根据电机起动阻抗及起动特性来选择合理的起动设备，减少起动过程故障的发生。对于高压电机，试验方法测取起动过程动态参数及起动特性不易实现，需要一种切实可行的方法进行仿真计算。本文根据国内外对感应电机起动特性、阻抗及温升的研究现状，分析总结目前计算方法中的优缺点，深入研究电机起动过程电、磁、热之间的关系，提出电机动态参数、起动特性及动态温升的计算方法。本文对起动过程电机内的饱和效应和集肤效应进行研究。根据动态过程电机内磁通的分布情况，采用磁网络法对电机内饱和漏磁通进行计算。紧凑型高压电机，少极数时定子轭部较长，且磁通密度较高，轭部饱和严重；另外，，为改善磁密分布，紧凑型高压电机常采用磁性槽楔。因此，建立磁网络模型时，需要考虑电机轭部饱和及磁性槽楔的影响。为提高计算的准确性，建立了电机齿槽相对和齿齿相对两种位置下的磁网络模型，根据磁路的定律对漏磁通进行计算。建立了分层法模型模拟集肤效应，对槽高进行离散，给出了集肤系数的计算方法。电机起动属于瞬态过程，需要用动态理论来分析电机起动特性。为减少计算量，根据坐标变换和矢量变换的理论推导出感应电机在两相坐标系下的状态方程。结合转动系的运动方程，给出了起动电流、电磁转矩、起动时间的计算方法，公式简单、计算方便、可节省计算时间。建立并求解电机风阻网络模型，得到电机内部冷却气体流量的分布，结合电机动态特性曲线对电机发热和散热进行计算，得到起动过程电机绕组平均温升的变化曲线。根据绕组温升限值对电机起动过程发生堵转时的安全运行时间进行计算，分析了不同负载对电机温升的影响。考虑起动过程电机阻抗、电流及温升之间的相互影响关系，对其进行耦合计算，提高了电机起动过程计算的准确性，通过实验验证了本文所提出计算方法的准确性。论文的研究成果为新系列电机的设计和保障其安全运行提供了参考，具有较高的实用价值。
[Abstract]:With the improvement of related technology in motor field, high efficiency and high power density motor becomes the developing trend. YJKK series compact high voltage motor is a new product of motor industry in our country, which is two grades lower than the center of YKK series motor on average. The decrease of volume makes the surface heat dissipation area decrease, and the power density and voltage level increase, which makes people pay more attention to its starting characteristics and temperature rise. When the load starts, the starting time is long, the starting current will make the winding temperature rise rapidly, and the large load may lead to the motor not starting normally. In the starting process, rotor impedance and starting current are the important basis for judging the winding temperature rise, and the starting characteristics (current-rotational speed, torque and rotational speed) are the important indexes to evaluate the starting performance of induction motor and to judge whether the motor can start normally. The user needs to select reasonable starting equipment according to the starting impedance and characteristics of the motor, so as to reduce the occurrence of the fault in the starting process. For the high voltage motor, it is difficult to realize the dynamic parameters and the starting characteristics of the starting process by the test method, so a practical method is needed to carry out the simulation calculation. According to the research status of induction motor starting characteristics, impedance and temperature rise at home and abroad, this paper analyzes and summarizes the advantages and disadvantages of the current calculation methods, deeply studies the relationship among electric, magnetic and heat during motor starting, and puts forward the dynamic parameters of the motor. The calculation method of starting characteristic and dynamic temperature rise. In this paper, the saturation effect and skin effect in starting motor are studied. According to the distribution of magnetic flux in the dynamic process of the motor, the magnetic network method is used to calculate the saturated flux leakage in the motor. For compact high voltage motor, the stator yoke is longer, the flux density is higher, and the yoke is saturated seriously. In addition, in order to improve magnetic density distribution, magnetic slot wedge is often used in compact high voltage motor. Therefore, the influence of the saturation of the yoke and the magnetic slot wedge should be taken into account in the establishment of the magnetic network model. In order to improve the accuracy of the calculation, a magnetic network model is established under the two positions of the relative tooth slot and the tooth, and the leakage flux is calculated according to the law of magnetic circuit. A stratified model is established to simulate the skin effect, and the height of the groove is discretized, and the calculation method of the skin collecting coefficient is given. Motor starting is a transient process, which needs to be analyzed by dynamic theory. According to the theory of coordinate transformation and vector transformation, the state equation of induction motor in two-phase coordinate system is derived. Combined with the motion equation of rotation system, the calculation methods of starting current, electromagnetic torque and starting time are given. The formula is simple, the calculation is convenient and the calculation time can be saved. The wind resistance network model of the motor is established and solved, and the distribution of the cooling gas flow inside the motor is obtained. Combined with the dynamic characteristic curve of the motor, the heat and heat dissipation of the motor are calculated, and the variation curve of the average temperature rise of the motor winding during the starting process is obtained. According to the limit value of winding temperature rise, the safe running time of motor during starting process is calculated, and the influence of different load on motor temperature rise is analyzed. Considering the interaction among the impedance, current and temperature rise of the motor during the starting process, the coupling calculation is carried out to improve the accuracy of the calculation of the starting process of the motor. The accuracy of the proposed calculation method is verified by experiments. The research results of this paper provide a reference for the design of new series motors and ensure their safe operation, and have high practical value.
【学位授予单位】：哈尔滨理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM346

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