【作者】 刘陵顺；

【导师】 胡育文；

【作者基本信息】 南京航空航天大学 ， 电力电子与电力传动， 2007， 博士

【摘要】 定子双绕组感应发电机是为了适应变速范围较宽的风力发电以及航空、战车等电源系统的新发展而提出的。它的定子设有两套绕组,一套为功率绕组,输出端接有励磁电容、整流器、滤波电容,输出变频交流电或整流直流电压;另一套为控制绕组,接有静止的励磁变换器,可以为发电机连续地提供励磁,解决了感应发电机在转速和负载都大范围变化时,所需要的大范围变化的励磁电流调节问题。通过系统参数的优化设计和一定的控制策略,在宽变速范围和变负载条件下,可以以小容量的励磁变换器有效地控制大容量的电能输出,或者以小电流的励磁变换器有效地控制大电流的电能输出,保持输出电压的幅值恒定,有效地减小系统的成本、体积和重量。两套定子绕组在电气上没有直接连接,只是通过磁耦合,容易达到控制的高性能。本文系统地推导了定子双绕组感应发电机系统在abc和dq坐标下的数学模型和等效电路以及带整流桥负载时的动态数学模型。对电机内部运行的物理过程进行了分析和描述,揭示了通过控制绕组励磁变换器调节发电机无功使功率绕组输出电压稳定的运行机理。给出了电磁转矩方程、运动方程以及基本性能计算式等。采用解析法系统地研究了不同绕组结构形式下如双重单层联接、三层联接以及四层联接等定子双绕组感应电机槽漏抗及谐波互漏抗的计算问题,归纳总结了一套统一的槽漏抗与不同节距系数之间的数学计算公式,并可以推广到m相电机的计算中;研究了实现两套绕组dq轴互漏抗解耦的条件。所得结论为定子双绕组感应电机设计中绕组分布及参数计算提供了理论依据。研究了变速系统的定子双绕组感应发电机的运动规律。对控制绕组电流变化规律与电机参数、负载大小、转速及变比、功率绕组励磁电容的大小等参数之间的关系进行了详细地探索,提出了通过功率绕组励磁电容的选择来降低控制绕组励磁变换器容量的优化方法。研究了用小容量变换器控制大容量电能输出的优化策略,即电机设计和系统设计同一优化的概念,为了使励磁变换器的容量最小,电机的参数和功率侧的励磁电容容量同时优化。根据电机设计的基本原则,以磁路、电路设计为核心得到了设计计算的公式及设计步骤及性能校核方法。采用一种动态全域映射收缩算子的复合形法编制出相应的计算机辅助设计系统。对一台应用于18kW的270V高压直流输出电压的样机进行了优化设计,分析了主要参数对性能的影响规律,并对其进行了有限元电磁场的分析。利用具有全局优化搜索能力的改进遗传算法对系统参数的优化结果进行了验证。优化结果表明,该优化方法可以在1:2.5的转速变化范围内,负载从空载到额定负载变化,控制绕组与输出功率的容量比可以降到1/3左右,效率可达90%以上,这对于降低控制绕组的容量和铜耗,提高效率,降低系统运行的成本及体积、重量是很有意义的,对于风力发电、航空、战车等变速范围较大的场合有一定的工程应用价值。研究了低压大电流发电系统的特殊设计方法。充分利用定子双绕组感应发电机系统有两个定子绕组的特点,提高控制绕组与功率绕组的匝数比来提高控制绕组的电压,使控制绕组励磁变换器的电流降低。同时省去功率侧的励磁电容器和控制侧的滤波电感,构成高电压小电流的新型励磁控制系统,降低了系统的成本、体积和重量。建立了定子双绕组感应发电机的系统仿真模型,研究了1:2.5的宽变速运行的励磁变换器自励建压问题,对整流型负载下的稳态特性、动态特性、变速运行特性以及纯阻性负载下的变速运行进行了系统地仿真研究,对两种负载的运行性质进行了对比总结,系统仿真结果与样机计算结果吻合。建立了基于dSPACE试验平台的定子双绕组感应发电机系统的实时试验模型;对优化设计的18KW、270V高压直流输出的样机系统进行了1:2变速比范围的试验研究,对额定转速下系统的变载运行规律以及励磁电容改变时的变速运行规律进行了试验研究,得到了与仿真结果及理论设计结果相吻合的结果,验证了所发现的控制绕组电流变化规律的正确性以及所提优化策略的正确性。更多还原

【Abstract】 Wind generating system and high voltage DC stand-alone supply system of aviation and tank have presented new demands for induction generator. The dual stator-winding induction generator is presented for these demands. Two sets of three-phase windings are embedded in the stator slots, the one referred as power winding with excited capacitors C, supplies power to DC load via a bridge rectifier. The other termed the control winding, is connected PWM excited converter, which supplies only the reactive power and none of active power to control the output voltage stable. Solving the problem of large varying excited current adjusting of induction generator with variable load and speed. By the optimal design of machines parameters and excited capacitor and proper control strategy, the minimal capacity converter can be used to control large power output or the minimal current of converter can be used to control large current output under wide speed range and load, which reduces the cost,volumes and weight of system .Both the two sets of windings have none of electrical connection but magnetic coupling exiting, so the harmonic from the converter of control winding has little disturbance on the load, and the electromagnetic compatibility and efficiency have been improved more.The general mathematic model and equivalent circuit under axis of dq and abc reference of dual stator-winding induction machine with rectifier load are derived. The physical process inside machine is proposed. The operational mechanism of the system is revealed. Electromagnetic torque and motional equation and basic characteristic expression are given.The analytical calculations of slot and harmonious leakage reactance of dual stator-winding induction machine with different winding structure, such as double single-layer and three-layer and four-layer, are presented systematically, the relevant formulas with different pitch are derived, and generalized to m-phase machines. The decouple of dq axes leakage reactance between of the two sets of windings is studied. These conclusions will provide theoretical guidance to the winding distributing and parameters calculating.The operational laws of this system under variable speed are studied firstly. The capacity ratio between control winding and power winding is proposed. The relation between reactive capacity and parameters of machine, load, rotating speed, speed ratio and exciting capacitors is analyzed. The distribution of reactive power with variable speed and laws of winding’s currents are given. The determination of excited capacitors to minimize the reactive power of control winding under variable load and speed is given. The optimal strategy of minimal capacity converter can be used to control large power output is studied. The simultaneously optimal design concept of dual stator-winding induction generator and excited capacitor with wide speed range is researched, which the machines parameters and excited capacitor are simultaneously optimized to make the minimizing to reactive power of excited converter. The designing features of high voltage DC induction generator are given. The design formulae and processes and collating means based circuit and magnetic path are presented. The CAD are designed by complex method with dynamic full reflection and retraction operator. A prototype of 18kW and 270V high voltage DC is designed, The parameters effects on the capacity of control winding is analysised, and finite element method is given.The improved real-coded genetic algorithm is used to test the designed results theoretically. The results show this scheme has prominent effect to reduce reactive power of control winding, and the capacity of converter can be reduced to 1/3 of output rated power, which makes the cost, dimension of inverter much smaller.The special design strategy of minimal current converter can be used to control large current output is studied. When the output voltage of power winding is very low and the output current very high,the winding turns ratio between the two winding is choosed to reduced the current of control winding.The excited capacitor can be canceled.These can reduce the cost and volume of the system.The universal simulation model of dual stator-winding induction generator system is established by MATLAB/SIMULINK. The starting-up process by the PWM excitation converter is resolved. And the performances of steady and dynamic operation with variable speed are simulated based direct flux stator control of control winding. The performances under resistor load and bridge rectifier are compared.The Real-time experimental model based dSPACE is setup, and the experiment is done with a 18 kW and 270V rectified DC output prototype. The experiments are done under different load and different capacitors and 1:2 speed ratio. The experimental results are anastomose with those of simulating, which validates the control winding current laws and the optimal strategy. The operational laws of the system with variable load are experimented.更多还原