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Chaotic nature of renewable energy sources connected with nonlinear loads may cause serious problems to the utility grid, e.g. voltage and frequency disturbances, harmonic pollution. Due to that, many European governments have set strict regulations to the grid energy injection. As a result, the power quality has become one of the major obstacles for nearly zero energy buildings to be connected with...
This paper presents a selective harmonics reduction for a 3(n+1) shared switch inverter topology utilizing optimal arrangement of the n-modulated signal. Under different modulation indices and operating power frequencies the purpose of the proposed procedure is to select an optimal load connection and/or modulation offsetting based on the desired objective function. Three performance indices are studied...
The star-configured modular multilevel converter is a promising topology for grid-connected storage as well as power-quality applications and motor drives. During operation, the ac output power generates substantial current pulsation at twice the output frequency in the modules, which causes additional loss and requires an increase of the module capacitance. This paper presents a common-mode voltage...
A hybrid modulation approach is proposed in this work, which allows to modulate the switches of the five level neutral point clamped inverter (5LANPC) with different switching frequencies. Some of the switches are controlled with a low switching frequency using six-step modulation and Optimized Pulse Patterns (OPPs), whereas the rest are modulated with a high switching frequency using Carrier-Based...
This paper proposes an induction motor drive scheme generating multilevel twenty-four sided voltage space vector structure using single DC source. The topology consists of basic units with DC-source fed main three-level flying-capacitor (FC) inverter cascaded with two low-voltage floating-capacitor fed H-Bridge cells (CHB). The generated space vector structure has six concentric 24-sided polygons...
This work introduces a novel surface registration method based on foliation. A foliation decomposes the surface into a family of closed loops, such that the decomposition has local tensor product structure. By projecting each loop to a point, the surface is collapsed into a graph. Two homeomorphic surfaces with consistent foliations can be registered by first matching their foliation graphs, then...
This paper presents a case study of different control approaches for a single phase Dual Active Bridge (DAB) based MVDC Shipboard power system (SPS). The Line Regulating Converters (LRCs) are based on DAB topology and the load side converters or Point of Load Converters (POLs) are based on buck topology. The tightly controlled POLs exhibit a constant power load (CPL) behaviour, which has a destabilising...
The paper presents a comprehensive Power Quality (PQ) solution to improve grid current harmonics and light intensity flickers in large scale LED lighting networks. Low cost and low power LED lamps exhibit current harmonic contents due to their nonlinear characteristics. A large scale lighting network requires tens to hundreds LED lamps installation, the resultant harmonic currents pollute the grid...
Battery energy storage systems play a vital role in renewable energy based electric power grids. Inverters are essential to integrate DC energy storage devices such as batteries to AC power grids. In this paper, a cascaded boost inverter topology based single-phase grid-connected battery energy storage system is presented. A current feedback ripple reduction method is used to mitigate the second-order...
A control strategy to manage the circulating current content in a Modular Multilevel Converter in direct AC-AC topology is proposed in this article. The converter is connected in three-phase YDY configuration which forms a closed delta path for free current circulation while keeping outsider waveforms with low THD content. Circulating current correction becomes necessary face to any kind of unbalance...
In this paper, a new 11-level topology of symmetrical Multilevel Inverters (MLIs) is proposed. The proposed topology offers reduced number of components as compared with conventional and recently published topologies. The Selective Harmonic Elimination (SHE) is adapted for switching modulation that removes undesired harmonics. A comparative analysis of proposed topology with other proposed topologies...
This paper proposes a space vector modulation algorithm for an asymmetrical six-phase open-end winding permanent magnet synchronous motor (OEWPMSM) supplied by two two-level six-phase voltage source inverters(VSIs) with common mode voltage suppression. The VSIs are fed from two equal and isolated DC voltages. A six-phase open-end winding PMSM model is developed based on the vector space decomposition...
The modular multilevel converter (MMC) is considered to be the state of the art in medium- and high-voltage application. The nearest level modulation (NLM) method is one of the most popular modulations, however, when applied to MMC with small number of sub-modular (SM), the output waveforms contain large harmonic components. This paper proposes a modified NLM method. By changing the traditional rounding...
This paper provides conclusions on design and laboratory tests of a hybrid rectifier prototype which employs the newest generation of SiC transistors and diodes. For the presented hardware prototype the AC-DC efficiency is about 98%. Based on simulation analysis and the practical realization pros and cons of this topology were identified. It should be noted that hybrid rectifiers importance is growing...
One of the major drawbacks of Finite Control Set — Model Predictive Control (FCS — MPC), is the high switching frequency, besides a spread harmonic spectrum. Despite of this, the FCS — MPC provides excellent speed to changes of references and disturbances. In this work we present a control strategy based on FCS — MPC that allows a reduction of the switching frequency in steady state, increasing the...
This work analyzes some possible converter switching strategies so as to achieve higher efficiency and better current waveforms in a high power and low cost three-phase and three-level active AC-DC conversion.
Compression and pumping applications represent a majority of all rotating machinery in modern industrial plants. Increasingly in the past two decades, electric motors are replacing turbines as the prime mover of choice for large rotating equipment. The use of electrically driven equipment is now widespread even for critical applications. As semiconductor technology evolves, adjustable speed drives...
This paper presents both analysis and experimental verification of applying Selective Harmonic Elimination (SHE) technique for cascaded half-bridge multilevel inverters. The inverter units are fed from PV modules throughout step-down dc-to-dc converters to regulate the inverter input voltage. The inverter has to be asymmetric which allows more possibility to connect PV modules to get maximum possible...
This paper presents an improved single phase seven-level active rectifier architecture controlled by finite control set model predictive control (FCS-MPC). The FCS-MPC is designed to enable power conversion with a unity power factor and generate seven level voltage waveform at the input. The proposed active rectifier architecture reduces harmonic contents of the rectifier input current by producing...
Increased switching speed of semiconductors are reducing losses, but increasing emissions. EMC compliance becomes increasingly difficult in power electronics. A reactive attitude is unwanted, often due to the possible increased costs of solutions. Converter topologies that can inherently reduce emissions are preferred This paper demonstrates that harmonic cancellation is possible in a novel topology...
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