A novel quasi-two-stage multifunctional inverter (QMFI) for photovoltaic (PV) applications is proposed in this article. With the help of the quasi-two-stage architecture, part of active power can be directly transferred from PV arrays to the grid or load within a single power conversion stage and hence improve the efficiency. In addition to active power transfer, both the realization of maximum power point tracking (MPPT) and compensation of nonactive current (i.e., reactive, harmonic, or unbalanced current) of the QMFI are considered. A mathematical model of the QMFI is presented to guide the control parameter design. Meanwhile, an analysis model based on the rotating frame is proposed to derive the space vector pulsewidth modulation strategy of the QMFI, and also, offer straightforward insight into the influence of nonactive current compensation on quasi-two-stage active power flow. Compared with traditional solutions, the QMFI can realize active power delivery with higher efficiency and also keep functions of achieving MPPT and enhancing power quality. The feasibility and effectiveness of the proposed solution are verified with a 3-kVA prototype.

中文翻译：

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具有电能质量控制和增强转换效率的准两级多功能光伏逆变器

本文提出了一种用于光伏 (PV) 应用的新型准两级多功能逆变器 (QMFI)。借助准两级架构，部分有功功率可以在单个功率转换级内直接从光伏阵列传输到电网或负载，从而提高效率。除了有功功率传输之外，QMFI 的最大功率点跟踪（MPPT）的实现和无功电流（即无功、谐波或不平衡电流）的补偿都被考虑在内。提出了 QMFI 的数学模型来指导控制参数设计。同时，提出了基于旋转坐标系的分析模型，推导出QMFI的空间矢量脉宽调制策略，直接了解无功电流补偿对准两级有功潮流的影响。与传统解决方案相比，QMFI可以实现更高效率的有源电力输送，同时还保留了实现MPPT和提高电能质量的功能。所提出的解决方案的可行性和有效性通过 3-kVA 原型验证。