【作者】 郭磊；

【导师】 游江； 赵建伟；

【作者基本信息】 哈尔滨工程大学 ， 控制工程（专业学位）， 2024， 硕士

【摘要】 随着经济的快速发展,电力系统所需要提供的电能日益增加,尤其是对高质量电能的需求不断增长。逆变器作为电力系统中关键的电力电子设备,其输出的电能质量和稳定性会直接影响到负载的稳定运行。传统的三相三桥臂逆变器虽然可以满足基本的生活电力需求,但由于负载种类的多样化,尤其是非线性与不平衡负载的普遍存在,三相三桥臂逆变器输出的电压会产生三相电压畸变以及输出电压不平衡的问题,导致输出电能的质量较低。因此本文选取三相四桥臂拓扑结构作为研究对象,针对非线性与不平衡负载引起的输出电压波形质量问题,重点从调制方法以及控制策略展开研究。首先,本文对三相四桥臂拓扑结构进行数学分析,结合非线性负载与不平衡负载的电压电流关系,将静止坐标系和同步旋转坐标系下的数学模型进行综合对比,选取在同步旋转坐标系建立逆变器的平均值模型。然后采用傅里叶分解法和对称分量法,分析了非线性与不平衡负载的电流谐波以及谐波对逆变器输出电压的影响,找出逆变器输出电压质量低的原因。由于三维空间矢量脉宽调制算法的计算复杂程度高以及正弦脉宽调制算法直流侧电压利用率低,本文依据三相四桥臂拓扑结构设计了一种改进的快速脉宽调制方法并给出了其原理。该方法结合了两种调制算法的优点,有效简化了逆变器的调制过程。在逆变器的控制策略上,首先对非线性与不平衡负载产生的扰动信号进行分析,采用重复控制器将扰动信号的内模引入控制器内,设计了一套基于改进重复控制算法的双闭环控制系统。然后,针对控制器响应速度较慢的缺点,本文对控制器的内模进行优化,设计了1/6周期的重复控制器,有效提高了系统对非线性负载扰动信号的响应速度。由于改变内模后的重复控制器对不平衡负载产生的扰动信号抑制能力不足,本文设计准比例谐振控制器对不平衡负载产生的扰动信号进行抑制,提高了逆变器对不平衡负载的带载能力。最后,基于STM32H743芯片搭建了一台三相四桥臂逆变器的实验样机,对系统的电路参数进行设计,对本文所设计的控制方法和调制原理进行了闭环实验,验证了本文提出的调制策略和控制方法的有效性。实验结果表明,本文所设计的三相四桥臂逆变器对非线性与不平衡负载的适应性较好,输出电压波形的质量显著提高。更多还原

【Abstract】 With the rapid development of economy,the electric energy required by the power system is increasing day by day,especially the demand for high-quality electric energy is growing.As the key power electronic equipment in power system,the output power quality and stability of inverter will directly affect the stable operation of load.Although the traditional three-phase three-leg inverter can meet the basic needs of domestic power,due to the diversification of load types,especially the widespread existence of nonlinear and unbalanced loads,the output voltage of three-phase three-leg inverter will produce three-phase voltage distortion and output voltage imbalance,resulting in low output power quality.Therefore,this paper chooses the topology of three-phase four-leg inverter as the research object,aiming at the quality problem of output voltage waveform caused by nonlinear and unbalanced loads,focusing on the modulation method and control strategy.First of all,this paper made a mathematical analysis of the topology of the three-phase four-leg inverter,combined the voltage and current relationship between the nonlinear load and the unbalanced load,made a comprehensive comparison between the mathematical models in the stationary coordinate system and the synchronous rotating coordinate system,and chose the synchronous rotating coordinate system to establish the average value model of the inverter.Then Fourier decomposition method and symmetric component method were used to analyze the current harmonics of nonlinear and unbalanced loads and the influence of harmonics on the output voltage of the inverter,and found out the reason for the low output voltage quality of the inverter.Due to the high computational complexity of the three-dimensional space vector pulse width modulation algorithm and the low voltage utilization of the sinusoidal pulse width modulation algorithm,an improved fast pulse width modulation method based on the topology of the three-phase four-leg inverter was designed and its principle was given.This method combined the advantages of the two modulation algorithms and simplifies the modulation process of the inverter effectively.In the control strategy of inverter,the disturbance signal generated by nonlinear and unbalanced load was analyzed first,and the internal mode of disturbance signal was introduced into the controller by a repetitive controller.Then,aiming at the shortcoming of slow response of the controller,this paper optimized the internal model of the repeating controller,and designed a repeating controller of 1/6 period,which effectively improved the response speed of the system to the nonlinear load disturbance signal.Because the repetitive controller after changing the internal mode was insufficient to suppress the disturbance signal generated by the unbalanced load,the quasi-proportional resonant controller was designed in this paper to suppress the disturbance signal generated by the unbalanced load,and improved the carrying capacity of the inverter to the unbalanced load.Finally,an experimental prototype of three-phase four-leg inverter based on STM32H743 chip was built,the circuit parameters of the system were designed,and the control method and modulation principle designed in this paper were tested by closed-loop experiments,which verified the effectiveness of the modulation strategy and controlled method proposed in this paper.The experimental results show that the three-phase four-leg inverter designed in this paper has good adaptability to nonlinear and unbalanced loads,and the quality of output voltage waveform was significantly improved.更多还原