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Grid-connected AC/DC power converters play a crucial role in integrating renewable energies, smart grids, and motor drives. Consequently, high-performance control techniques have constantly attracted the interest of researchers. Predictive direct power control (P-DPC) strategies are promising control techniques for these converters, due to their fast transient response. However, standard P-DPC strategies cannot effectively compensate for steady-state errors when the switching frequency is reduced, due to model inaccuracies. This work proposes a new optimal switching sequence direct power control (OSS-DPC) strategy, which enhances the converter discrete-time model by estimating the grid currents and voltages at each commutation instant within a sampling period. As a result, the proposed OSS-DPC provides a fast dynamic response with reduced overshoot and improved steady-state performance, outperforming the standard P-DPC strategies.

Transfomerless grid-connected inverters with common-grounded circuit architectures and single-stage dy-namic voltage boosting gain are promising candidates for PV energy conversion applications. In this work, a new five-level (5L) variant of this category of inverters is introduced. Key features of the presented inverter are the reduced current stress profile, modularity, uniform peak voltage stress across the switches, higher power handling capability, and bi-directional power flow operation. The proposed topology is comprised of two input inductors, two capacitors, and ten power switches. Through a modular design with a phase-shifted SPWM technique, the injected grid current can be shared among the modules, while the size of the grid-interface filters can be reduced. The working principle of the converter is discussed, and some simulation and experimental results are presented to validate its feasibility.

Single-stage grid-connected PV inverters with a transformerless (TL) concept have been a hot spot research topic in both the academia and industry in the latest years. Dynamic voltage boosting feature through the adjustment of de duty cycle, reduced value of the current and voltage stress across the switches, common-ground (CG)-based circuit architecture and capability of larger number of output voltage levels generation can make these types of inverters an attractive option for an efficient and compact design. In this paper, a novel seven-level (7L)-CG-based TL inverter is proposed, which possesses all the above-mentioned features for a compact design. The working principle and modulation strategy are discussed. Some simulation results are presented to attest a proper performance of the converter.

This article proposes a novel three-port converter with a fault-tolerant (FT) capability to reconFigure automatically under different switching fault conditions, i.e., open circuit fault (OCF) or short circuit fault (SCF) of the power transistors, and to continue achieving different control objectives such as effective battery charging, maximum power point tracking (MPPT) and output voltage regulation. The proposed fault-tolerant design with a one-level redundancy structure enhances the reliability of traditional three port converters (TPCs), but it also addresses the component failure while different modes of operations using fewer components by incorporating dual-input single-inductor structure into the converter design. Simulation results are presented to explain the performance of the proposed converter during different fault conditions and the reconfiguration mechanism during these conditions.

Dynamic voltage boosting feature in photovoltaic (PV) grid-integrated application is a necessity to achieve the maximum power point of PV arrays as well as boost the input voltage to the necessary dc-link voltage requirement. Such feature is usually achieved by incorporating a front-end boost or buck-boost dc-dc converter tendem with a conventional two or three-level inverter. However, such an integration cannot efficiently meet many IEEE strict grid codes from the power quality, ground leakage current, and the overall efficiency per power density aspects. The aim of this paper is to present a new five-level (5L) inverter with an integrated single-stage dynamic voltage-boosting concept and a common-grounded (CG) feature. As a result, the concern of ground leakage current is addressed through the provided CG feature, whilst both the power quality and overall efficiency of the system are improved with a 5L single-stage boosted output voltage waveform. To confirm the effectiveness of the proposal, apart from the circuit description, some experimental results are also presented.

Single-source inverters with integrated switched-boost (SB) module and single-stage energy power conversion architecture have become a popular solution in many power electronics applications. This paper presents a novel topology of such types of inverters, which offers a modular design with a dynamic voltage boosting feature over a wide range of input voltages. The basic configuration of the proposed topology is able to generate three output voltage levels. It is comprised of an integrated SB module and a Quasi-H-Bridge (QHB) cell. The QHB cell consists of a self-balanced floating capacitor and four power switches, and the SB cell consists of a boost inductor and a single power switch. A five-level boosted output voltage can be achieved through the differential connection of two identical QHB cells utilizing a single SB module. The circuit description of the proposed topology, a comparative study, and the simulation and measurement results are given to verify the feasibility of this proposal.

Multilevel inverters (MLIs) based on the flying capacitor (FC) concept are beneficial in many renewable energy-based applications due to their compactness, low current stress on semiconductor devices, and reasonable thermal behavior for high-power applications. However, the recently developed FC-based topologies suffer from half dc-link voltage utilization and a variable high-frequency common-mode voltage (HF-CMV). The aim of this paper is to propose an FC-based family of MLIs with a five-level (5L) output voltage, full dc-link voltage utilization, and low HF-CMV. Using redundant states and the phase-shifted sinusoidal PWM technique, the value of the flying capacitor has been reduced significantly. The performance of the converter has been verified using Gallium Nitride (GaN) power switches. Circuit description and a brief comparative study with existing MLIs are given to justify the suitability of the topology.