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多电平逆变器毕业设计论文

摘要近年来在运动控制领域多电平中压变频器的开发研究得到了广泛关注,多电平逆变器使得电压型逆变器的大容量化、高性能化成为可能,具有降低开关管耐压值,减小开关管电压应力,改善输出波形质量,提高系统的电压和功率等级等优点,研究和开发多电平逆变器,无论在技术上还是在实际应用上都有十分重要的意义。

所以多电平技术由于越来越广泛的应用于高压大功率领域。

目前,在高压大功率领域中,二极管箝位型三电平变换器是研究最多,应用最广的一种多电平拓扑结构。

[1]本文主要对二极管箝位型三电平逆变器进行研究,以此拟作为今后进一步研究的基础。

论文首先详细地介绍了三电平逆变器的工作原理,并在此基础上详细分析了其特性,综合比较了多电平逆变电路三种典型拓扑结构的优缺点。

然后,研究了三电平逆变器空间电压矢量调制技术的基本原理,分析了空间电压矢量调制算法相对于其它方法的优点。

详细分析了空间电压矢量调制算法,并给出PWM波的计算公式和开关动作次序。

对开关矢量的作用顺序作了有利于中点电压控制的优化,使仿真和实现都比较容易。

最后,分析了三电平逆变器直流侧电容电压不平衡问题的产生。

介绍了一种实现中点电压平衡的理论。

提出了一种基于MATLAB的建模方法,并通过MATLAB/SIMULINK仿真结果验证了该方法的正确性。

采用MATLAB/SIMULINK仿真软件对所推导的三电平逆变器SVPWM调制算法进行了仿真分析,证明了该调制算法的正确性。

并与两电平SVPWM调制算法的仿真进行了比较,进一步证明了三电平SVPWM调制算法在谐波抑制和减小器件开关损耗方面的优越性。

关键词:多电平逆变器;空间矢量脉宽调制;中点平衡;MATLAB/SIMULINK仿真ABSTRACTRecently, with the fast development of power Electronics, micro electronic technique, computer technology and modern control theory, The multilevel inverters have got large attention in power electronic industry and the applications of the high powered A.C motors’ motion control.Multilevel technology has become all effective and practical solution for high-voltage high-power application field. As described in many literatures, using multilevel technology, the voltage stress on switches will be reduced, the shape of output waveform will be improved and the rate of voltage and power can be increased too. Diode-clamped three-level inverter is the most widely used and investigated topology at present.As the basis of further researches, the paper mainly focuses on the control system of diode-clamped three-level inverter.First, the principle of two-1evel inverter is detailed to introduced,and based on it, the paper deeply analyzes fundamental principle,performance and development of three-level inverter,and compares the advantages and disadvantages of three kinds of typical multilevel circuit.Then, the principle of the voltage vector modulating technique is studied,the advantage of the voltage vector modulating calculation is analyzed comparing with other means. The next in order,the three-1evel space voltage vector control method is analyzed in detail.The formulas about PWM pulse and the order of switches action are also presented.The order of switches action is also optimized in this text,which call be propitious to the control of midpoints voltage.At the same time,the simulating and implement can also be easier.At last, the production of capacitance voltage’s imbalance belongs to direct current sides of three.1evel inverter is analyzed in this text.Then, A theory which can realize the balance of midpoint’s voltage is introduced;At the same time,a modeling method found on MATLAB is hereby brought forward.and then this method’s correctness is validated by emulation results. The SVPWM modulating means of three.1evel inverters is simulated by MATLAB,and the correction of modulating means is proved.Comparing with the SVPWM modulating results of two-level inverters,The superiority is further proved,which belongs to the SVPWM modulating means ofthree-level inverters at the aspects of restraining harmonic and minishing switching wastage.Keywords:Multi-level ,Inverter,SVPWM,Neutral point palanceMATLAB/SIMULINK,Simulation目录第一章绪论 (1)1.1 多电平逆变器产生的背景及现状 (1)1.2多电平逆变技术的概述 (2)1.2.1多电平逆变器分类 (2)1.2.2多电平逆变技术的概述 (2)1.2.3不同拓扑结构多电平逆变器的优缺点 (4)1.3本文的意义及主要工作 (5)第二章多电平逆变器的基本工作原理 (7)2.1 多电平逆变器的主电路 (7)2.2 三电平逆变器的基本工作原理 (8)2.2.1多电平逆变器基本结构分析 (8)2.2.2多电平逆变器串并联拓扑分析 (10)2.3 三电平逆变器的特性 (11)第三章多电平逆变器空间矢量脉宽调制策略 (13)3.1多电平逆变器的SVPWM调制策略 (13)3.1.1空间合成矢量定义 (13)3.1.2多电平电压空间矢量脉宽调制(sⅦwM)策略 (14)3.2一种减小开关损耗的SVPWM方法 (23)3.3本章小结 (24)第四章MATLAB 仿真及分析 (25)4.1 MATLAB和SIMULINK简介 (25)4.2三电平逆变器系统仿真模型 (25)4.2.1 参考电压矢量仿真模块 (26)4.2.2小三角形区域判断的仿真 (26)4.2.3扇区判断的仿真 (27)4.2.4时间计算仿真 (28)4.3仿真结果 (29)4.4三电平逆变器中点电位平衡的仿真 (30)第五章硬件电路设计 (32)5.1 逆变器控制系统的硬件总体结构 (32)5.2 TMS320LF2407DSP控制芯片 (32)5.3 IGBT驱动 (33)5.4 上电缓冲延时电路 (34)5.5电压电流采样电路 (35)5.6 PWM信号输出电路 (36)第六章结论 (37)6.1 论文总结 (37)6.2 感想 (37)致谢 (39)参考文献 (40)附录A:英文资料 (41)附录B:英文资料翻译 (53)第一章绪论1.1多电平逆变器产生的背景及现状[2] [3] [4]近年来,多电平逆变器在高压大功率场合的应用受到越来越多的关注,各种电路拓扑结构及控制方法纷纷被提出和研究。

所谓的多电平逆变器(MultilevelinverteO的桥臂上有4个或更多的电力半导体器件,它通过对直流侧的分压和开关动作的不同组合,实现多电平阶梯波输出电压,可以使波形更加接近正弦波。

其拓扑结构种类较多,大致可以分为:二极管钳位型、飞跃电容型和独立直流电源级联多电平三种拓扑结构,其中二极管钳位型多电平拓扑结构运用最广泛。

它能有效地提高换流系统的耐压、降低输出电压谐波和开关损耗,在电力系统的大功率应用中受到普遍的重视。

多电平逆变器是在1981年由Nabae等人提出的“中点钳位PWM逆变器(Neutral-Point-Clamped PWM Inverter,NPC-PWM逆变器)”的基础上发展起来的,其后在高压大功率变频调速器方面得到了广泛的应用。

尽管Nabae未明确提出多电平逆变器的概念,但该逆交器本身就是二极管钳位多电平逆变器的雏形。

多电平逆变器的一般结构是有几个电平台阶成阶梯波以逼近正弦输出电压。

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