【作者】 王成智；

【导师】 邹云屏；

【作者基本信息】 华中科技大学 ， 电力电子与电力传动， 2005， 硕士

【摘要】 随着光伏发电等分布式发电系统的发展,多电平技术已经从传统的高压、大功率向中、低压功率的应用方面渗透,其目的在于利用多电平逆变器输出电压谐波少,电磁干扰小的优势提高电源质量,缩减电源体积和成本。本文引入一种新型单相五电平逆变电路,对其工作原理和调制方法进行分析,通过与其它五电平逆变器拓扑结构的比较,该电路使用的开关器件最少,适用于中低功率场合的应用要求。为充分发挥新型五电平逆变器的优势并探讨多电平技术与波形控制技术的融合问题,本文将重复控制技术应用在新型五电平逆变器的控制上,获得了良好的效果。本文首先分析了重复控制器优化波形的原理,并就其对扰动响应慢的缺点,引入状态反馈极点配置+重复控制结构,增设电容电流反馈内环,提高整个系统的响应速度,同时也改善了逆变器的控制特性。为缩减系统成本,本文使用降维状态观测器替代电容电流采样回路,通过仿真与实验验证:观测器可以准确地预测电容电流变化,满足内环控制需要。本文通过绘制系统Nyquist曲线分析重复控制器各部分对控制对象的稳定性的影响,通过绘制系统Bode 图的方法分析重复控制器各部分对受控对象的响应速度和谐波抑制能力的影响,并得出了相关的结论; 同时给出了从控制对象模型测定->重复内模滤波器->重复控制增益->二阶滤波器->相位补偿环节设计的重复控制器设计方法。论文还分析了逆变器的极点配置方法与其对控制对象的特性影响,并给出了电容电流的数字化降维观测器的设计方法和设计通式。为验证设计系统,搭建了基于F240 控制器的整个实验电路,实验结果说明了经典的波形控制技术能够应用于多电平逆变器,整个系统具有良好的动态与稳态性能。更多还原

【Abstract】 In recently years, multilevel converts have received a wide attention and becomes the hot point on power electronics research. Following the distributed generation system such as solar electrical energy generation, the multilevel technology has used in the inverters with medium or low voltage, due to the multilevel inverters have many advantages as: the output voltage of them have low distortion, the inverters can use the smaller filter and hence the level of the electromagnetic interface(EMI). The costs and the volume of the inverter will decrease. A novel single-phase five-level inverter is presented, and then the topology and its derivation, modulation methods and operation states are analyzed. It is the inverter that uses the least power switches in the single-phase five-level inverters, so it is suitable to applications with the medium and the low voltage. Technology of the output waveform is another hot point on power electronics research, it ensures the whole system with the well steady-state and dynamic-state characteristic. To exert the advantages of the novel inverter and study the feasibility of using the multilevel technology and the technology of output waveform, a repetitive controller is added to the system and the results are excellent. The paper reviews the process of the repetitive control, and analyzes the theory of improving the output waveform when a repetitive controller is employed in. The repetitive technology can keep the controlled plant with perfect steady-state characteristic, but its dynamic response is very slow. It can not ensure the qualities of the power supply used alone. The feedback of the capacitor current can quicken the dynamic response and improve the characteristics of the controlled plant. In order to expediently observe the capacitor current and reduce the costs, a digital dimensionality reduction observer is designed to replace the unnecessary sampling circuits. The simulation and experiment results show that the observer can effectively forecast the capacitor current. The paper give a design step of the repetitive controller, considered from the influences to the stability, error convergence speed and harmonic rejection capability of the system. First is the frequency characteristic mensuration of the inverter, second is the filter in the repetitive generator, third is the 2nd order filter, then the phase compensator is ensured and the last one is the design of the repetitive gain. The influence of the stability can be analyzed from the Nyquist curve of the system and the ones of the error convergence speed and harmonic rejection capability can be achieved from the Bode maps. And the influence of the pole assignment to system is analyzed, and the design process of the digital dimensionality reduction observer is also given. A platform based on DSP is constructed to verify the feasibility of the controller and the topology, the experiment results indicate that the system holds an excellent steady-state and dynamic-state characteristics. It is proved that the traditional technology of the output waveform can be transplanted to the multilevel inverters.更多还原