Model Predictive control design for switched inductor quasi-Z-source inverter in comparison with the traditional two-stage inverter based on Photovoltaic.

全球矿物燃料的短缺和环境问题的增加引起了人们对发现可再生能源的极大兴趣。光伏发电系统已显示出成为全球主要发电来源的潜力，其增长势头强劲且持续。为了向公用电网提供交流电源，已经采用了几种电力电子变换器。电力电子系统的成本占总安装成本的很大一部分。随着太阳能电池技术的发展，太阳能组件的价格大幅下降。然而，电力转换器的价格几乎保持不变。降低电源变流器的成本已成为并网光伏系统亟待解决的问题。电压源逆变器（VSI）已广泛用于直流/交流功率转换，但由于其局限性，z源逆变器（ZSI）被引入。ZSI有一个额外的零矢量，穿透开关状态，这在传统的VSI中是禁止的。新的ZSI有利地利用穿透状态通过打开相腿的上下开关来提高直流母线电压。因此，ZSI可以提高电压并产生所需的输出电压，该输出电压大于可用的直流母线电压。此外，逆变器的可靠性大大提高，因为由误传或电磁干扰引起的通射不再会破坏逆变器。从而为降压升压功率转换提供了一种可靠、高效的单级结构。然而，ZSI从直流电源中提取不连续电流，因此它不适合光伏应用。准z源逆变器（qZSI）是传统z源逆变器的改进版本，提出用相同的有限升压因数来取代它。但是光伏系统的输出电压范围很宽，这也需要一个高的逆变器升压范围。为了提高升压因数和利用qZSI的优势，本项目将qZSI开关电感器设计为单级逆变器，用于光伏系统与公用电网和交流负载的接口。本课题的主要目标是实现基于PV系统的新型开关电感qZSI的模型预测控制。本文将从逆变器的效率、对无源器件的要求以及对电源开关的电压和电流压力等方面与传统的两级逆变器进行比较。为了公平比较，将使用相同的组件设计两个3kw逆变器，并在相同的条件下进行评估。此外，MPC将在瞬态和稳态运行期间与传统PI控制器进行比较。最后，一种潜在的、更便宜的、更简单的、强大的单级逆变器有望用于光伏应用。这些新技术将有助于以更有效和经济的方式增加太阳能。

The shortage in the global fossil fuels and the increase in environmental concern have initiated a major interest for discovering renewable energy sources. PV generation systems have shown the potential to become a main source of electrical power generation for the whole world with powerful and persistent increase. Several power electronic converters have been employed in order to provide AC power to the utility grid. The cost of power electronic systems represents a substantial portion of the overall installation costs. With the development of solar cell technology, the price of solar modules has dropped dramatically. However, the prices for the power converters almost remain the same. Lowering the cost of the power converters has become a very urgent issue for grid connected PV systems.Voltage source inverters (VSI) have been widely used for DC/AC power conversion but due to their limitations, the Z-source inverter (ZSI) was introduced. ZSI has an additional zero vector, shoot-through switching state, which is forbidden in the traditional VSI. The new ZSI advantageously utilizes the shoot through states to boost the DC bus voltage by turning on both upper and lower switches of a phase leg. Therefore, the ZSI can boost the voltage and produce a desired output voltage which is greater than the available DC bus voltage. In addition, the reliability of the inverter is greatly improved because the shoot-through due to misgating or EMI can no longer destroy the inverter. Thus it provides a reliable and efficient single stage structure for buck-boost power conversion. However the ZSI draws a discontinuous current from the DC source, thus it is not suitable for PV applications. Quasi Z-source inverter (qZSI) is an improved version of the classical ZSI which is proposed to replace it with the same limited boost factor. But PV systems have a wide range of output voltage which needs also a high inverter boost range. To increase the boost factor and utilize the advantages of qZSI, the switched inductor qZSI will be designed in this project as a single-stage inverter to interface PV system with the utility grid and the AC loads.The main objective of this project is to realize the model predictive control (MPC) of the new switched inductor qZSI based on PV system. The proposed inverter will be compared with the traditional two-stage inverter in light of inverter efficiency, the requirement of the passive components and voltage and current stress on the power switches. For a fair comparison, two 3 kW inverters will be designed using the same components and evaluated under the same conditions. Moreover, the MPC will be assessed in comparison with the conventional PI controller during the transient and the steady-state operation. At the end a potential, cheaper, simpler, and robust single-stage inverter for PV applications is expected. These new technologies will help increase the solar power in a more efficient and economical way.