共直流母线双三电平逆变器开绕组异步电机调速系统研究

发布时间：2019-03-31 00:17

【摘要】：近年来,多电平逆变器凭借其输出电压谐波含量低、开关损耗小、对功率器件的开关应力低等特点,在中、高压大功率的场合得到了越来越广泛的应用。多电平逆变器拓扑经过多年来长期的研究和发展,现如今已形成了几种比较典型的结构,其中尤以二极管钳位型三电平逆变器的研究和应用最为广泛。为此,本文对以二极管钳位型三电平逆变器为功率单元的共直流母线双三电平逆变器拓扑进行了分析和研究,并建立了相应的开关模型,根据建立的开关模型绘制出了共直流母线双三电平逆变器的空间电压矢量图,将该空间电压矢量图与二极管钳位型五电平逆变器的空间电压矢量图进行对比分析可发现这两者基本相同,由此可说明共直流母线双三电平逆变器亦属于五电平逆变器的范畴。针对共直流母线双三电平逆变器拓扑介绍了空间电压矢量180°解耦调制方法的基本原理,然后利用平行四边形法则对空间电压矢量180°解耦调制方法进行改进,由此得到了空间电压矢量120°解耦调制方法,并对这两种不同空间电压矢量解耦调制方法分别从系统零序电压消除、逆变器直流侧电容电压平衡控制、最大线性调制范围以及逆变器输出谐波含量等几个方面进行了对比分析。发现不管是从对共直流母线双三电平逆变器系统零序电压消除方面还是从逆变器直流侧电容电压平衡恢复能力方面来看,空间电压矢量120°解耦调制方法明显优于空间电压矢量180°解耦调制方法。然后根据文中介绍的电压谐波总畸变率THD计算方法,绘制出了两种不同解耦调制方法下共直流母线双三电平逆变器输出相电压THD随基波频率f的变化曲线,并对这两种不同解耦调制方法所产生的逆变器输出相电压谐波含量进行了FFT对比分析,由此发现这两种不同解耦调制方法下逆变器输出相电压的谐波分布情况并不相同。本文分别在三相静止、两相静止、两相旋转这三种坐标系下分析和建立了开绕组异步电机相应的数学模型,然后在建立相应数学模型的基础上,采用了基于转子磁链定向的矢量控制方法实现了开绕组异步电机的闭环控制,以提高开绕组异步电机的调速性能。最后,在共直流母线双三电平逆变器开绕组异步电机调速系统的仿真平台和实验平台上,验证了两种不同的空间电压矢量解耦调制方法以及基于转子磁链定向的开绕组异步电机矢量控制方法。仿真和实验结果有效的验证了本文理论研究内容的正确性和有效性。
[Abstract]:In recent years, multilevel inverter has been more and more widely used in medium, high voltage and high power because of its low harmonic content of output voltage, low switching loss and low switching stress of power devices. After many years of long-term research and development, the topology of multi-level inverter has formed several typical structures, especially the diode-clamped three-level inverter is the most widely used. In this paper, the topology of common DC bus dual three-level inverter with diode clamp three-level inverter as power unit is analyzed and studied, and the corresponding switching model is established. According to the established switching model, the space voltage vector diagram of the dual three-level inverter with common DC bus is plotted. By comparing the space voltage vector diagram with that of diode-clamped five-level inverter, it is found that the space voltage vector diagram is basically the same as that of diode-clamped five-level inverter, which indicates that the dual three-level inverter with common DC bus also belongs to the category of five-level inverter. The basic principle of 180 掳decoupling modulation method of space voltage vector is introduced for the topology of common DC bus dual three level inverter, and then the 180 掳decoupling modulation method of space voltage vector is improved by using parallelogram rule. Thus, the 120 掳decoupling modulation method of space voltage vector is obtained, and the two different space voltage vector decoupling modulation methods are eliminated from the zero sequence voltage of the system, and the DC side capacitor voltage balance of the inverter is controlled. The maximum linear modulation range and the output harmonic content of the inverter are compared and analyzed. It is found that both the zero sequence voltage elimination of the common DC bus dual three level inverter system and the recovery ability of capacitor voltage balance on the DC side of the inverter are considered. The space voltage vector 120 掳decoupling modulation method is obviously superior to the space voltage vector 180 掳decoupling modulation method. Then according to the THD calculation method of total voltage harmonic distortion rate introduced in this paper, the curves of output phase voltage THD of common DC bus double three-level inverter with fundamental frequency f under two different decoupling modulation methods are plotted. The harmonic content of the inverter output phase voltage produced by the two different decoupling modulation methods is analyzed by FFT. It is found that the harmonic distribution of the output phase voltage of the inverter is not the same under the two different decoupled modulation methods. In this paper, the corresponding mathematical models of open winding asynchronous motor are analyzed and established in the three coordinate systems of three-phase static and two-phase rotation respectively, and then on the basis of establishing corresponding mathematical models, The vector control method based on rotor flux orientation is used to realize the closed loop control of open winding induction motor in order to improve the speed regulation performance of open winding induction motor. Finally, on the simulation platform and the experiment platform of the open winding asynchronous motor speed regulation system of the common DC bus double three-level inverter, Two different methods of space voltage vector decoupling modulation and vector control method of open winding induction motor based on rotor flux orientation are verified. The results of simulation and experiment verify the correctness and validity of the theoretical research in this paper.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM343

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