【作者】 李东；

【导师】 王卫；

【作者基本信息】 哈尔滨工业大学 ， 电气工程， 2009， 硕士

【摘要】 随着太阳能、风能等分布式发电的开发与利用,逆变器的应用日益广泛。传统的电压源型全桥逆变器和电流源型全桥逆变器在理论上存在着一些缺陷,电压源型全桥逆变器是一个降压式逆变器,要得到更高的电压,就必须增加一级升压电路,这样会增加成本,降低效率,且同一桥臂的上下器件不能同时导通;电流源型全桥逆变器是一个升压型逆变器,要得到较低的电压,就需要增加一级降压电路,这同样会增加成本,降低效率,且任何瞬间,至少应有上面的一个器件和下面的一个器件被触发且维持导通状态。新型Z源逆变器可以解决这些缺陷,具有输出电压范围宽,同一桥臂的上下器件可以直通,电源既可以是电压源也可以是电流源等优点。此外,在光伏并网发电系统中采用Z源型逆变器还可以充分适应光伏阵列输出电压大范围波动的特点,并且并网电流没有死区,谐波更小,可靠性更高。本文比较深入的分析了Z源型逆变器的拓扑及工作原理,研究了Z源型逆变器的控制策略。着重分析了电网电压前馈的作用和电流型并网控制策略,并说明了直通占空比和正弦占空比的制约关系。基于光伏电池的数学模型,从工程应用的角度建立了光伏电池的仿真模型,分析了光伏电池的外特性,说明温度和光照强度对光伏电池输出特性的影响;详细的研究了扰动观测法。对Z源逆变器的硬件和软件分别进行了设计。在硬件方面,给出了Z源电容、Z源电感,以及采样电路的设计过程。在软件方面,阐述了整个控制程序的思路,给出了算法分析和软件设计流程图。以MATLAB/Simulink为仿真平台,搭建了Z源逆变器的模型,仿真波形和部分实验波形证明了Z源结构的合理性和可行性。更多还原

【Abstract】 With the development and utilization of distributed power generation, such as solar energy and wind energy, inverter is used widely. There are some defects in traditional voltage source inverter(VSI) and current source inverter(CSI)theoretically. The VSI is a buck inverter. To get a higher voltage, an additional boost converter is needed to obtain a desired output. The additional power converter stage increases system cost and lowers efficiency. The upper and lower devices of each phase leg can not be gated on simultaneously. The CSI is a boost inverter. To get a lower voltage, an additional buck converter is needed. The additional power conversion stage also increases system cost and lowers efficiency. At least one of the upper devices and one of the lower devices have to be gated on and maintained on at any time.To overcome the above problems of the traditional VSI and CSI, the new Z-source inverter is introduced. It can boost-buck voltage, minimize component count, increase efficiency and reduce cost. The upper and lower devices of each phase leg can be gated on simultaneously and need no dead-time. The source is either voltage source or current source. In addition, Z-source inverter can be fully adapted to wide range output voltage fluctuations in PV system. No dead-time ensures the harmonic of the grid-connected current smaller, more reliable.The paper analyses the Z-source topology and operating principle, studies the control strategies. The paper stresses the importance of grid voltage feed-forward, analyses grid current control strategies and explains the relationship between short through duty cycle and sinusoidal duty cycle.Based on the math model of PV cells, the simulation model is built to explain the characteristics of PV cells from the perspective of engineering applications. The case that temperature and irradiation has an effect on PV cells can be expedient simulated. The perturbation and observation method is discussed deeply.The hardware and software of Z-source inverter are designed in this paper. In terms of hardware, the design process of Z-source capacity, Z-source inductance and sampling circuit is given. In terms of software, the paper describes the control procedure in the whole and gives the algorithm and software design flow chart. The simulation model of Z-source inverter is built based on MATLAB/Simulink. The simulation and experimental results prove the rationality and feasibility of Z-source.更多还原