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Abstract-Grid connected power converters play a key role in several applications such as integration of renewable energy sources and motor drives. For this reason, the development of high performance control strategies for this particular class of power converters has increasingly attracted the interest of both academic and industry researchers. This paper presents the predictive Optimal Switching Sequence Direct Power Control (OSS-DPC) algorithm for grid connected converters. The OSS-DPC method belongs to the predictive direct power control (P-DPC) family and provides the desired power references by calculating globally optimal switching sequences. To address computational and implementation issues, an efficient control algorithm, named reduced OSS-DPC (ROSS-DPC) is introduced. The implementation of the proposed control strategy in a standard DSP is evaluated on a two-level power converter prototype working as a STATCOM. Experimental results show algorithm's potential to provide high performance during both transient and steady states.

In this paper, a model predictive control (MPC) based on optimal switching sequences (OSSs) for a singlephase grid-connected full-bridge neutral-point-clampled (NPC) power converter is presented. The predictive control algorithm is formulated in terms of OSSs, which was originally proposed to govern three-phase power converters. In this work, the OSS concept is extended to control singlephase power converters. The proposed MPC algorithm belongs to the continuous control set MPC (CCS-MPC) and is able to provide fixed switching frequency while handling system constraints. The proposed algorithm has been experimentally tested in an NPC power converter prototype. Experimental results show the desired fixed switching behavior in the steady state condition and the intrinsic fast dynamic provided by MPC during transients. Furthermore, the test outcomes demonstrate the robustness of the proposed controller under large system parameter deviations.

Solar systems have become very competitive solutions for residential, commercial and industrial applications for both stand-alone and grid connected operations. This paper presents an overview of the current status and future perspectives of solar energy (mainly photovoltaic) technology and the required conversion systems. The focus in the paper is put on the current technology, installations challenges, and future expectations. Various aspects related to the global solar market, the PV modules cost and technology, and the power electronics converter systems are addressed. Research trends and recommendations for each of the PV system sectors are also discussed.

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Cascaded H-bridge multilevel converters are usually applied for high-power systems with independent dc sources. It can be used as PV inverter or to operate independent battery stacks. In these cases, as each dc source can be working at different operational points, conventional modulators lead to high distorted output waveforms degrading the converter performance. In this paper, a modulation method as a modified version of conventional phase-shifted PWM is presented when the CHB converter has a large number of power cells. This method is an extension of a previous technique only suitable for CHB converters with three power cells per phase. Simulation results show the good performance of the proposal with higher number of cells.