Grid-connected inverters with a multilevel output voltage and an integrated dynamic voltage boosting feature are promising to achieve higher overall efficiency/power density, reduced output filter size, and better power quality. However, the input current of such a single-stage system might be pulsating with low- and high-frequency ripple contents in a single-phase grid-connected application. To tackle this challenge, active power decoupling (APD) can be used to keep the input current flat and reduce the current stress of the devices with an efficient performance. On the other hand, the grid voltage is usually nonideal in practice, polluted with the harmonics. This causes additional complexity in the closed-loop control system to maintain the injected power quality. The aim of this article is to apply a tailored closed-loop APD control on a recently proposed single-source single-stage switched-boost (SB) five-level converter leading to further enhancing its overall efficiency without adding any extra circuit components. A distinctive feature of the proposed solution is using a single proportional–resonant controller with a filtered feedforward term to achieve APD, even under a distorted grid voltage condition. This solution can also be applied to other single-stage SB-based converters as long as their input current before integration of the APD control contains a low-frequency ripple content. A 2-kW SiC-based prototype is built to validate the feasibility and accurate performance of the proposed method via experiments when connected to a grid with harmonic pollution.

中文翻译：

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电网污染电压条件下集成有功功率解耦的单级开关升压并网五电平变换器

具有多级输出电压和集成动态升压功能的并网逆变器有望实现更高的整体效率/功率密度、更小的输出滤波器尺寸和更好的电能质量。然而，在单相并网应用中，此类单级系统的输入电流可能会产生低频和高频脉动内容的脉动。为了应对这一挑战，可以使用有源功率去耦（APD）来保持输入电流平坦，并以高效的性能降低器件的电流应力。另一方面，实际中电网电压通常不理想，受到谐波污染。这导致闭环控制系统保持注入电能质量的额外复杂性。本文的目的是在最近提出的单源单级开关升压 (SB) 五电平转换器上应用定制的闭环 APD 控制，从而进一步提高其整体效率，而无需添加任何额外的电路组件。该解决方案的一个显着特点是使用具有滤波前馈项的单个比例谐振控制器来实现 APD，即使在电网电压失真的情况下也是如此。该解决方案还可以应用于其他基于 SB 的单级转换器，只要它们在集成 APD 控制之前的输入电流包含低频纹波内容即可。搭建了一个 2 kW SiC 原型机，通过实验验证了该方法在连接到有谐波污染的电网时的可行性和准确性能。