Switched capacitor multilevel inverter topologies are attractive among industrial power electronics researchers due to their applicability in sustainable energy systems such as renewable energy source (RES) applications. In this paper, a new switched capacitor (SC)-based grid-tied seven-level inverter is proposed for renewable energy sources (RES) applications. The proposed inverter can generate a seven-level output voltage waveform with voltage boosting ability and a gain factor of 3. Also, the proposed topology can provide the self voltage balancing for capacitors. The most important challenge of the SC-based topologies, i.e., the capacitor charging spike current, is solved by applying a soft charging circuit in the charging loop of the capacitors. The soft charging circuit consists of an inductor and a power diode in the capacitor charging path. Using a small size inductor in the soft charging circuit, the proposed inverter can limit the input current spikes. Comprehensive experiment results and comparisons are presented to verify the accurate performance of the proposed inverter.@en

Quasi-Z source (qZS) multilevel inverters have become popular in sustainable energy systems, particularly in photovoltaic (PV) systems. This study proposes a qZS five-level nested neutral point clamped (5L-NNPC) inverter, benefiting from continuous input current, high voltage gain, and insignificant voltage stress across semiconductors. The proposed topology provides a common ground between the input sources and the inverter's DC link, thus entirely eliminating leakage current, making it a suitable candidate for PV applications. Moreover, model predictive control (MPC) is employed to regulate the voltages of flying capacitors and the output current of the 5L-NNPC inverter. The study also includes analyses of steady-state performance, circuit design, efficiency, and control considerations. Finally, experimental results are presented to validate the converter's performance.@en

This article presents a new high step-up quasi-Z-source-based dc-dc converter with switched boost techniques and voltage multiplier cells. Compared with the conventional Z-source-based converters, this converter not only can achieve high voltage gain but also has good efficiency at high output voltage and higher output power conditions. Most of the Z-source-based converters suffer from high current stress across the power mosfets and the operation in lower power. However, the other important advantages include very low input current ripple, low voltage and current stress across the power switches, no duty ratio limitation, and leakage current elimination by providing the common grounded feature. So, in this topology, the null of the output is connected to the negative terminal of the input dc source directly. Therefore, the leakage current can be eliminated completely. As a result, the proposed converter is suitable for renewable energy sources (RESs)' applications, such as photovoltaic (PV) systems. The mathematical analysis, operating principle for the proposed converter, and comparison with other converters are evaluated. Finally, in order to verify the accurate performance of the proposed converter and confirm the mentioned features of the proposed converter, a 1-kW laboratory prototype is built and tested.

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