基于单相多级联逆变器的特性研究
发布时间：2018-11-17 07:02
【摘要】：随着电力电子交流技术的不断发展,各种先进的控制技术层出不穷。由于受电力电子器件电压容量的限制,传统的两电平变频器通常采用“高-低-高”方式经变压器降压和升压来获得高压大功率,或采用多个小容量逆变单元经多绕组变压器多重化来实现,这使得系统效率和可靠性下降。因而,人们希望实现直接的高压逆变技术,而多电平功率变换技术因其在高压大功率应用场合的广阔前景,就成为了电力电子领域的研究热点。围绕多电平变换器,新型电路拓扑及相关调制策略层出不穷,级联型多电平逆变器由于其具有开关应力小,输出波形优,易于封装和扩展等优点,越来越多地被应用于中高压频率调速、柔性交流输电和高压直流输电等高压大功率场合。本文首先介绍了多电平逆变器的产生背景及其发展现状,对它的几种拓扑结构进行了详细介绍,并对各自的特点和适用场合进行了比较分析,从而引出H桥级联型多电平逆变器的优越性能和广阔应用前景,接下来,对H桥级联逆变器的结构和工作机理进行了重点介绍,并在此基础上,引出了级联逆变器的PWM调制方法,在对各种方法的分析比较下,引出了载波相移正弦脉宽调制(C P S-S P WM)策略,并对它进行了深入剖析研究。另一方面,在载波相移控制下的级联逆变器在调制过程中,是通过载波对正弦信号进行调制的,这会产生和载波有关的谐波分量,而这些输出谐波频率和幅值已成为衡量PWM多级联逆变电路的重要指标之一,因此也必须对CPS-SPWM调制策略的谐波进行准确分析并给予有效地抑制。本文最后也重点研究了单相级联型多电平逆变器在CPS-SPWM调制下的的输出特性,重点是谐波的变化规律:随着H桥单元个数的增加,输出波形会越来越接近正弦波,谐波含量也会越小;同时随着调制度和载波频率等参数的变化,输出波形谐波情况也发生相应变化。最终,应用MATLAB进行了仿真分析,并且结合实际电路完成了实验分析,验证了逆变器的输出规律,达到了预期效果。
[Abstract]:With the continuous development of power electronic AC technology, various advanced control technologies emerge in endlessly. Because of the limitation of the voltage capacity of the power electronic devices, the traditional two-level inverter usually adopts the "high-low-high" mode to obtain high voltage and high power through the transformer voltage reduction and boost voltage. Or multiple small capacity inverters are realized by multi-winding transformers, which reduces the efficiency and reliability of the system. Therefore, people want to realize direct high-voltage inverter technology, and multilevel power conversion technology has become a research hotspot in the field of power electronics because of its broad prospect in high-voltage and high-power applications. Around multilevel converters, new circuit topologies and related modulation strategies emerge endlessly. Cascaded multilevel inverters have the advantages of low switching stress, excellent output waveform, easy encapsulation and expansion, etc. More and more applications are used in high voltage and high power applications, such as medium and high voltage frequency regulation, flexible AC transmission and high voltage direct current transmission. In this paper, the background and development of multilevel inverter are introduced, and several kinds of topology are introduced in detail, and their characteristics and applications are compared and analyzed. Thus, the superior performance and broad application prospect of H-bridge cascaded multilevel inverter are introduced. Then, the structure and working mechanism of H-bridge cascaded inverter are introduced emphatically, and on this basis, The PWM modulation method of cascaded inverter is introduced. Under the analysis and comparison of various methods, the (C P S-S P WM) strategy of carrier phase shift sinusoidal pulse width modulation is introduced, and it is deeply analyzed and studied. On the other hand, in the process of modulation, the cascaded inverter controlled by carrier phase shift modulates the sinusoidal signal through the carrier, which will produce the harmonics associated with the carrier. These output harmonic frequencies and amplitudes have become one of the important indexes to measure PWM multi-cascade inverter circuits. Therefore, the harmonic of CPS-SPWM modulation strategy must be accurately analyzed and effectively suppressed. In the end of this paper, the output characteristics of single-phase cascaded multilevel inverter under CPS-SPWM modulation are also studied. The emphasis is on the law of harmonic variation: with the increase of the number of H-bridge units, the output waveform will be more and more close to sine wave. The harmonic content will be smaller; At the same time, with the change of modulation and carrier frequency, the harmonic of output waveform also changes. Finally, the simulation analysis is carried out by using MATLAB, and the experimental analysis is completed in combination with the actual circuit. The output rule of the inverter is verified and the expected effect is achieved.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464
本文编号：2336887
[Abstract]:With the continuous development of power electronic AC technology, various advanced control technologies emerge in endlessly. Because of the limitation of the voltage capacity of the power electronic devices, the traditional two-level inverter usually adopts the "high-low-high" mode to obtain high voltage and high power through the transformer voltage reduction and boost voltage. Or multiple small capacity inverters are realized by multi-winding transformers, which reduces the efficiency and reliability of the system. Therefore, people want to realize direct high-voltage inverter technology, and multilevel power conversion technology has become a research hotspot in the field of power electronics because of its broad prospect in high-voltage and high-power applications. Around multilevel converters, new circuit topologies and related modulation strategies emerge endlessly. Cascaded multilevel inverters have the advantages of low switching stress, excellent output waveform, easy encapsulation and expansion, etc. More and more applications are used in high voltage and high power applications, such as medium and high voltage frequency regulation, flexible AC transmission and high voltage direct current transmission. In this paper, the background and development of multilevel inverter are introduced, and several kinds of topology are introduced in detail, and their characteristics and applications are compared and analyzed. Thus, the superior performance and broad application prospect of H-bridge cascaded multilevel inverter are introduced. Then, the structure and working mechanism of H-bridge cascaded inverter are introduced emphatically, and on this basis, The PWM modulation method of cascaded inverter is introduced. Under the analysis and comparison of various methods, the (C P S-S P WM) strategy of carrier phase shift sinusoidal pulse width modulation is introduced, and it is deeply analyzed and studied. On the other hand, in the process of modulation, the cascaded inverter controlled by carrier phase shift modulates the sinusoidal signal through the carrier, which will produce the harmonics associated with the carrier. These output harmonic frequencies and amplitudes have become one of the important indexes to measure PWM multi-cascade inverter circuits. Therefore, the harmonic of CPS-SPWM modulation strategy must be accurately analyzed and effectively suppressed. In the end of this paper, the output characteristics of single-phase cascaded multilevel inverter under CPS-SPWM modulation are also studied. The emphasis is on the law of harmonic variation: with the increase of the number of H-bridge units, the output waveform will be more and more close to sine wave. The harmonic content will be smaller; At the same time, with the change of modulation and carrier frequency, the harmonic of output waveform also changes. Finally, the simulation analysis is carried out by using MATLAB, and the experimental analysis is completed in combination with the actual circuit. The output rule of the inverter is verified and the expected effect is achieved.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464
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相关硕士学位论文 前1条
1 吴智超;混合多电平逆变器调制方法及输出波形解析[D];华中科技大学;2005年
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