【作者】 林晃；

【导师】 陈道炼；

【作者基本信息】 福州大学 ， 电力电子与电力传动， 2018， 硕士

【摘要】 准Z源逆变器具有单级升降压、桥臂可直通、开关管无死区以及输出波形质量高等优点。但是由于准Z源逆变器的升压因子受到调制比的制约,使得准Z源逆变器不适用于新能源发电低输入电压或宽范围输入电压的场合。因此在传统准Z源逆变器研究的基础上,提高其升压能力,具有重大的研究价值,是新能源发电领域的一个前沿课题。为提升准Z源逆变器的升压能力、功率密度以及系统性能等,本文研究分析了众多具有强升压能力的改进型准Z源逆变器,并提出了一种新颖的强升压能力的准Z源逆变器。对该逆变器的工作原理、调制方案、控制策略、磁集成设计方案以及关键电路参数等进行研究与设计,最后通过仿真与实验得到了重要的结论。新颖的单级单相电压型准Z源光伏并网逆变器,主要由磁集成阻抗网络、单相逆变桥、LCL滤波器等串联而成。根据逆变器的直通和非直通工作状态,推导得各储能电容电压、电感电流以及电压增益等表达式。并通过与其它准Z源逆变器的对比,可知所提出的准Z源逆变器升压能力强、功率开关器件与储能电容电压应力较小;分析了多种调制策略优缺点,并在采用简单升压SPWM调制策略的基础上,分析了高频开关过程的各个工作模态;对磁集成电感的交直流磁通进行分析,得到各磁阻表达式,并在此基础上对各绕组不同匝数选取下的等效电感以及电流纹波进行深入的研究,最后获得了实现储能电感电流零纹波的理论依据;对磁集成阻抗网络进行小信号模型建立,研究分析各参数变化对系统性能的影响,并通过仿真验证其分析的正确性。同时获得系统传递函数,在此基础上研究了储能电容电压外环、输出电流内环的控制策略以及光伏电池MPPT电压环的控制策略;为满足逆变器的各项性能指标,研究并推导出了储能电容、磁集成电感、功率开关器件以及LCL滤波器等元器件的设计准则。进行1kW80-110VDC/220V50HzAC新颖的单级单相电压型准Z源并网逆变器的PSIM仿真与实验,通过仿真与实验结果可知所提出的逆变器具有升压能力强、可靠性高,功率密度高以及输出波形质量好等优点,验证了电路拓扑和控制策略的正确性和可行性。更多还原

【Abstract】 Quasi-Z-source inverter can perform buck-boost conversion ability,bridge arm switches can be short and have no dead zones,and the AC output waveforms are of high quality.However,the boost factor of quasi-Z-source inverter is limited by modulation,it is not suitable for low input voltage and wide range of input voltage applications in new energy generation.Therefore,on the basis of the research of the traditional quasi-Z-source inverter,it is of great research value to improve its boost capacity.It is a frontier topic in the field of new energy generation.In order to improve the boost ability,power density and system performance of quasi-Z-source inverters.Based on the study of a large number of modified quasi-Z-source inverters with strong boost ability,an novel quasi-Z-source inverter with strong boost capacity is proposed.The working principle,modulation scheme,control strategy,magnetic integration design and key circuit parameters of the inverter are studied and designed.Finally,the important conclusions are obtained by simulation and experiment.A novel single-stage single-phase voltage-fed quasi-Z-source photovoltaic grid-connected inverter is composed of a magnetic integrated impedance network,a single phase inverter bridge and a LCL filter.According to the shoot-through state and nonshoot-through state of inverter,the expressions of capacitor voltage,inductance current and voltage gain are derived.Compared with other quasi-Z-source inverters,the proposed inverter has the advantages of strong boost ability,voltage stress of energy storage capacitor and power switch device are small.The advantages and disadvantages of various modulation strategies are analyzed,and the working modes of the high frequency switching process are analyzed.This paper analyzes the AC and DC magnetic flux of the magnetic integrated device and obtains the expressions of each magnetoresistance.On these basis,the magnetic integrated equivalent inductance and inductance current under different turns are studied deeply.Last the theoretical basis for the realization of energy storage inductor current zero-ripple wave is obtained.Based on the small signal model of a magnetic integrated strong boost ability impedance network,the influence of each parameter variation on the system performance is studied,and the correctness of the analysis is verified by simulation.The system transfer function is obtained and on this basis,the research analyzes the energy storage capacitor voltage outer loop,the output current inner ring control strategy and MPPT of photovoltaic cell voltage loop control strategy.To meet the performance indexes of the inverter,the design criterion of energy storage capacitance,magnetic integrated inductance,power switch device and LCL filter are derived.The 1kW 80-110VDC/220V50HzAC PSIM simulation and experiment of a novel single-stage single-phase voltage-fed quasi-Z-source photovoltaic grid-connected inverter have been completed.The results of PSIM simulation and the experimental results show that the proposed inverter has the advantages of strong boost ability,high reliability,high power density and good output waveform,and has verified the correctness and feasibility of the proposed circuit topology and control strategy.更多还原