基于不连续PWM调制的储能逆变器研究

发布时间：2018-04-27 05:27

本文选题：空间矢量脉宽调制 + 不连续脉宽调制　；参考：《电子科技大学》2014年硕士论文

【摘要】：随着全球性能源危机的不断加剧,基于新能源的分布式发电系统受到广泛关注和快速发展。由于太阳能、风能的随机性特点,导致在用电高峰期不能提供足够电能,在用电低峰时发出过剩电能的问题。电池通过储能逆变器与分布式电网的能量双向流动达到为分布式发电消峰平谷的作用,有效解决了以上不平衡问题。储能逆变器作为分布式发电中的一个重要组成部分,其变换效率的提高成为众多学者研究的热点。本文以储能逆变器为研究对象,围绕其调制策略、主电路参数设计等问题展开深入研究。首先,分析三相储能逆变器的数学模型与控制系统。在主电路拓扑结构和基本工作原理分析基础之上,建立系统abc、αβ、dq坐标下的数学模型,揭示了网侧电流与交流侧电压之间的数学关系。同时介绍了三相储能逆变器系统控制结构,分析了PWM调制在储能逆变器中的作用。其次,研究了不连续脉宽调制(DPWM)策略。首先介绍了PWM调制类型。然后,推导了4种DPWM调制策略的开关损耗与功率因数角之间的对应关系。论文以调制电压和输出电流大小为依据获得了零序电压表达式,根据零序电压与对应DPWM调制策略的关系,给出了损耗最小的调制信号实现方法。最后,通过一个周期PWM波形的傅里叶展开,得到了DPWM调制输出相电压的频谱分布,为后续LCL参数的优化设计提供基础。然后,针对DPWM调制输出谐波增大的问题,提出了一种新的LCL滤波器设计方法。通过LCL数学模型,分析了LCL型滤波器的滤波特性以及各个参数对其滤波效果的影响,给出了一种基于DPWM调制策略的LCL参数设计方法。根据以上对PWM调制输出相电压频谱分析结果,重新计算了DPWM调制和连续脉宽调制(CPWM)产生谐波电流值,并算出一组实验平台参数。最后,对以上的DPWM调制实现方法和新的LCL滤波器设计方法的正确性进行仿真和实验验证。通过对仿真和实验所得储能逆变器输出相电压的傅里叶分解,验证了谐波计算方法的正确性。实验结果表明储能逆变器效率得到了有效提高,同时输出电流谐波符合设计要求。这充分证明了本文所采用调制方法的有效性和LCL滤波器参数设计的正确性。
[Abstract]:With the aggravation of the global energy crisis, the distributed generation system based on new energy has received extensive attention and rapid development. Due to the randomness of solar and wind energy, it is difficult to provide enough power during the peak period and emit excess power at low peak. The energy bidirectional flow between the energy storage inverter and the distributed power grid can achieve the function of eliminating the peak and the valley of the distributed generation, which effectively solves the above imbalance problem. As an important part of distributed generation, the efficiency of energy storage inverter has become the focus of many scholars. In this paper, the energy storage inverter is studied, including its modulation strategy and the design of main circuit parameters. Firstly, the mathematical model and control system of three-phase energy storage inverter are analyzed. Based on the analysis of the topology and the basic working principle of the main circuit, the mathematical model of the system abc, 伪尾 -dq is established, and the mathematical relationship between the current on the grid side and the voltage on the AC side is revealed. At the same time, the control structure of three-phase energy storage inverter is introduced, and the function of PWM modulation in energy storage inverter is analyzed. Secondly, the discontinuous pulse width modulation (DPWM) strategy is studied. First, the PWM modulation type is introduced. Then, the relationship between switching loss and power factor angle of four DPWM modulation strategies is deduced. According to the magnitude of modulation voltage and output current, the expression of zero-sequence voltage is obtained. According to the relation between zero-sequence voltage and corresponding DPWM modulation strategy, the realization method of modulation signal with minimum loss is given. Finally, by Fourier expansion of a periodic PWM waveform, the spectrum distribution of the output phase voltage of DPWM modulation is obtained, which provides a basis for the optimization design of the subsequent LCL parameters. Then, a new design method of LCL filter is proposed to solve the problem of harmonic increase of DPWM modulation output. Based on the LCL mathematical model, the filtering characteristics of LCL filter and the influence of various parameters on its filtering effect are analyzed. A LCL parameter design method based on DPWM modulation strategy is presented. Based on the analysis of the output voltage spectrum of PWM modulation, the harmonic current generated by DPWM modulation and continuous pulse width modulation is re-calculated, and a set of experimental platform parameters are calculated. Finally, the correctness of the above DPWM modulation realization method and the new LCL filter design method are simulated and verified by experiments. The harmonic calculation method is verified by Fourier decomposition of the output phase voltage of the energy storage inverter obtained by simulation and experiment. The experimental results show that the efficiency of the energy storage inverter is improved effectively and the output current harmonics meet the design requirements. This fully proves the validity of the modulation method used in this paper and the correctness of the LCL filter parameter design.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

【参考文献】