【作者】 程如岐；

【导师】 赵庚申；

【作者基本信息】 南开大学 ， 微电子学与固体电子学， 2010， 博士

【摘要】 近年来,随着国民经济的飞速发展能源问题日益突出,发展和利用新能源是当前的重中之重。太阳能是新能源中最有发展前途的形式,利用太阳能进行发电对于缓解能源问题正在起着越来越重要的作用。全文从光伏并网系统的概况进行分析,详细分析了单级电压源型并网逆变器、带Boost电路的电压源型逆变器和Z源型逆变器的工作原理,总结并比较了它们的优缺点。论文在对Z源型逆变器的拓扑结构、工作原理、波形特性进行分析的基础上,以状态空间平均法对Z源逆变器分部分进行了建模和统一,并在模型的基础上针对于其不足提出了统一建模方案。同时论文详细介绍了SPWM和SVPWM的调制原理以及直通零矢量的控制方法,并介绍了基于本文DSP+FPGA硬件平台的单相SVPWM结合直通分段控制的调制原理与实现方法。并以建模结果和SVPWM为基础,设计了多环的控制系统结构。并对电流内环加入了重复控制的环节,有效的减少了并网电流谐波失真,取得了良好的控制效果。最终,以基于DSP+FPGA控制核心的电压模式Z源型并网逆变器实验平台进行实验,取得了良好的实验结果。主要研究内容包括：1.分析了光伏并网系统的组成及其各部分的作用。介绍了作为光伏并网系统核心的逆变器主要拓扑及其应用,详细分析了常用的三种电压型逆变器的拓扑结构、工作原理与特点。重点分析了Z源型逆变器的母线电压的二次谐波干扰问题的产生原因、危害以及抑制方法。针对这三种电压型逆变器从开关器件的功率(SDP)、直流侧无源器件大小、太阳能电池阵列输出电压和逆变器有源器件电压等级、系统效率等方面对它们进行了全面的比较分析,最后总结了Z源型逆变器的优缺点。2.对电力电子的常用的建模方法进行简单的介绍与总结。重点介绍了应用状态空间平均法对Z源型逆变器分为Z源升压子电路和逆变桥两部分分别进行建模的方法和建模结果。在分析此种方法不足的基础上,提出了一种统一建模的分析方法,并给出具体的建模模型和建模的结果。3.介绍了应用于逆变器的两种主要调制方法SPWM和SVPWM的原理及其生成方法。详细分析了针对于Z源型逆变器的SPWM和SVPWM的直通零矢量的几种控制方法,分析了几种控制方法的优缺点。最后,针对于采用传统的SPWM调制由于直通零矢量加入所带来的开关频率加倍问题,介绍了本文所采用的单相SVPWM的生成原理以及直通分段的直通零矢量控制方法并且详细介绍了通过FPGA生成单相SVPWM的方法。4.分析了电压型Z源型逆变器应用于光伏并网发电系统的控制策略。通过电路结构和控制目标将整个控制系统分为三个闭环结构：并网交流电流内环、母线电压外环、MPPT直通零矢量环。在对电流内环控制原理分析的基础上,针对于Z源型逆变器母线电压二次谐波的干扰问题,提出了针对于Z源逆变器的结合重复控制的电流内环控制方案,以抑制二次谐波的干扰。对于母线电压外环采用检测Z源电容电压与在线计算直通零矢量相结合的方式直接对母线电压进行闭环控制,从而提高了系统控制的精确度。5.分析了Z源型并网逆变器的硬件系统设计、DSP+FPGA硬件平台设计及其协调控制策略和仿真系统设计。硬件系统设计中包括基于DSP+FPGA的控制系统组成与设计、Z源型逆变器的主参数设计原则与方法。DSP+FPGA硬件平台设计中包括DSP与FPGA的协调控制策略、DSP与FPGA的功能框图。仿真系统设计主要包括Z源型逆变器中各个部分的仿真模型建立结构与实际的仿真模型。6.以基于DSP+FPGA硬件平台的Z源型并网逆变器实验平台和南开大学示范电站作为基础,对仿真结果与实验结果进行了分析对比,仿真结果与实验结果相互吻合,验证了系统设计的合理性与有效性。更多还原

【Abstract】 The problem of energy has become more serious as the social economy develops rapidly in recent years. As the most promising energy method, the use of solar energy is taking a more important role in generating electricity than before. The research and development of solar energy would have an active impact on the social economy. From the overview of photovoltaic on grid system, this paper made a detailed analysis of the principle of single-level voltage source inverter, voltage source inverter with Boost circuit and Z source inverter, summarized and compared their advantages and disadvantages, ultimately chose the Z source inverter circuit with more excellent performance. After analyzing the topology, operation principle and waveform of Z source inverter, this paper build model for each part of the system, based on state space average method, then combine them together. Against the shortcomings of the model, a unified model was proposed. This paper also introduced the modulation principle of SPWM and SVPWM as well as injection method of shoot-through zero vector. This article introduced principle and realization of single-phase SVPWM modulation combined with shoot-through segment injection based on DSP+FPGA hardware platform. Based on modeling results and SVPWM, a multi-loop control system was designed. And the current inner loop was improved by adding a repeated control link, effectively reducing the grid current harmonic distortion, achieved good control effect. Finally, experiments were conducted on voltage source Z Source on grid Inverter platform, which is controlled by DSP+ FPGA, ideal results were gained. The main contents include:1. Make an analysis of the composition and function of parts in the photovoltaic system. Introduce the topologies of inverter, which is the core of a photovoltaic on grid system, and their applications, a detailed analysis of topology, working principle and characteristics of three common-used inverters was also conducted. Focus on the causes, hazards, and suppression method of second harmonic interference of Z source inverter bus voltage. Against the three inverter, from the aspects of the switching devices power (SDP), the size of DC side components, photovoltaic module or fuel battery and inverter capacity and system efficiency, a full comparison and analysis were conducted. Finally, according to the comparison results and the actual design requirements of this article, Z source inverter was selected. And the advantages and disadvantages of Z source inverter were summarized.2. Modeling methods commonly used in power electronics were briefly introduced and concluded. The modeling results and state space averaging method used in Z source inverter were introduced in emphases. Z source inverter was divided into Z sources boost sub-circuit and the inverter bridge to model the two parts respectively. After analyzing the shortage of this method, a unified modeling approach was proposed and specific modeling models and modeling results were given.3. Introduce principle and generation of two main modulation methods-SPWM and SVPWM applied to inverter. Several injection methods of SPWM and SVPWM shoot-through zero vector in the Z source inverter were analyzed and the advantages and disadvantages of several control methods were summarized. Finally, against the switching frequency doubling problem caused by bringing in shoot-through zero vectors in the traditional SPWM modulation, principle of single-phase SVPWM as well as the shoot-through segment control methods used in this paper were introduced. And the method of generating the single-phase SVPWM by FPGA was given.4. Analyze the control strategy of Z source inverter in photovoltaic power generation system. In terms of circuit structure and control objectives, the entire control system consists of three closed-loop structure:the inner grid AC current loop, the outer bus voltage loop, MPPT shoot-through zero vector loop. Based on the analysis of control principle of inner current loop, for the problem of bus voltage second harmonic interference in Z source inverter, the repetitive control theory was proposed to improve the performance of inner loop. The method of testing Z source capacitor voltage and calculating shoot-through zero vectors on line was used to control the bus voltage directly to improve the control accuracy of the system.5. Analyze the design of Z Source Inverter hardware system, DSP+FPGA hardware platform and simulation system. Hardware system design includes control system based on DSP+FPGA and design of main parameters of Z source inverter. DSP+ FPGA hardware platform design includes coordinated control strategy between DSP and FPGA and the function structure of DSP and FPGA, Simulation system design includes the modeling of each part in Z source inverter.6. Based on experimental platform of Z source inverter, in which DSP+FPGA is controlling core and demonstration power station of NanKai University as a basis, the simulation and experimental results were analyzed and compared, the simulation results and experimental results agree with each other, the rationality and effectiveness of the system was verified.更多还原