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This paper presents a control method to balance, in average, the DC-link capacitor voltages while injecting power to the grid using an h-bridge neutral-point clamped five-level inverter grid-tied through an LCL filter. The method exploits the structure of a particular model representation of the system comprising a differential-mode part and a common-mode part, which turn out to be decoupled from one another. These decoupled representation enormously facilitates the control design as it can be performed as two independent processes as well. The first design process involves the differential-mode model part and focuses on the grid current injection, while the second design process focuses on the balance of the DC-link capacitors voltages, and is based on the common-mode model part. Out of this, two control components are derived, namely differential-mode and common-mode control components, which are later recombined to form the two control signals, one per inverter branch, required as references in a conventional modulation algorithm to generate the switching sequence. Numerical and experimental results are performed to evaluate the performance of the proposed controller for the h-bridge neutral-point clamped inverter subject to those interconnections.

The low energy storage quadratic boost converter (LES-QBC) was recently proposed as an advantageous topology in terms of reduced output voltage ripple and fast dynamic response, besides high power density and reduced energy storage. The topological configuration can be exploited mainly through a 180° phase shift between the controlled switch gate signals. Nevertheless, this feature imposes a relevant challenge in terms of modeling, since traditional averaging an ripple estimation techniques cannot provide an accurate approximation to the actual switching dynamics of the converter. Motivated by this issue, in this article, we provide a complete quantitative analysis of both the steady-state and dynamic behavior of the LES-QBC, giving a fine understanding of their operation in continuous conduction mode when a pulse width modulator is used. The voltage gain, ripple factor, and dynamic behavior are modeled considering parasitic resistances and a wide operation range for the input voltage and the load. The demonstrated performance corroborates the high value of the converter for several applications in the industry. Every theoretical prediction is fully validated via simulations and experimental results.