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

全球化石燃料的短缺和环境问题的加剧引发了人们对发现可再生能源的极大兴趣。光伏发电系统已经显示出成为全球主要发电来源的潜力，并具有强大和持续的增长。为了向公用电网提供AC电力，已经采用了若干电力电子转换器。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，太阳能电池组件的价格大幅下降。然而，电源转换器的价格几乎保持不变。降低功率变换器的成本已成为光伏并网发电系统中一个非常紧迫的问题，电压源逆变器（VSI）已被广泛应用于DC/AC功率变换，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，直通开关状态，这是禁止在传统的VSI。新的ZSI有利地利用直通状态来通过接通相脚的上开关和下开关两者来提升DC总线电压。因此，ZSI可以提升电压并产生大于可用DC总线电压的期望输出电压。此外，逆变器的可靠性大大提高，因为误选通或EMI导致的击穿不再会损坏逆变器。因此，它提供了一个可靠的和有效的单级结构的降压-升压功率转换。然而，ZSI从DC源汲取不连续的电流，因此它不适合PV应用。准Z源逆变器（qZSI）是对经典ZSI的一种改进，它的提出是为了用同样有限的升压因子来代替经典ZSI。但是光伏系统具有宽范围的输出电压，这也需要高的逆变器升压范围。为了提高升压因数，利用开关电感qZSI的优点，本课题将开关电感qZSI设计为单级逆变器，用于光伏系统与电网和交流负载的接口，主要目的是实现基于光伏系统的新型开关电感qZSI的模型预测控制（MPC）。将建议的逆变器与传统的两级逆变器的逆变器效率，无源元件的要求和功率开关管上的电压和电流应力进行比较。为了进行公平的比较，将使用相同的组件设计两个3 kW逆变器，并在相同的条件下进行评估。此外，MPC将在瞬态和稳态操作期间与常规PI控制器进行比较来评估。最后，一个潜在的，更便宜，更简单，和强大的单级逆变器的光伏应用。这些新技术将有助于以更有效和更经济的方式增加太阳能发电。

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.