<abstract xmlns="http://www.w3.org/1999/xhtml"> The flying-capacitor (FC) topology is one of the more well-established ideas of multilevel conversion, typically applied as an inverter. One of the biggest advantages of the FC converter is the ability to naturally balance capacitor voltage. When natural balancing occurs neither measurements, nor additional control is needed to maintain required capacitors voltage sharing. However, in order to achieve natural voltage balancing suitable conditions must be achieved such as the topology, number of levels, modulation strategy as well as impedance of the output circuitry. Nevertheless this method is effectively applied in various classes of the converter such as inverters, multicell DC-DC, switch-mode DC-DC, AC-AC, as well as rectifiers. The next important issue related to the natural balancing process is its dynamics. Furthermore, in order to reinforce the balancing mechanism an auxiliary resonant balancing circuit is utilized in the converter which can also be critical in the AC-AC converters or switch mode DC-DC converters. This paper also presents an issue of choosing modulation strategy for the FC converter due to the fact that the natural balancing process is well-established for phase shifted PWM whilst other types of modulation can be more favorable for the power quality.</abstract>

NATURAL CAPACITOR VOLTAGE BALANCE IN MULTILEVEL FLYING CAPACITOR CONVERTRS. A REVIEW OF RESEARCH ACHIEVEMENTS

<abstract xmlns="http://www.w3.org/1999/xhtml"> This paper presents the research results of a multilevel switched capacitor DC-DC converter (MLSCC). The converter, for power electronic applications, can operate in ZCS mode by utilizing resonant circuits for recharging the switched capacitors. The main focus of this article is an in-depth original analysis of the waveforms and the converter voltage ratio. The concept of the converter is verified by simulation results of the circuit in MATLAB/Simulink Sim Power Systems. The formulas given in the mathematical analysis are evaluated for example parameters of the components with the use of numerical approach in MATLAB software. Plot sets are presented in order to judge the influence of the parameters on converter performance. All non-expected relations are explained based on mathematical analysis. The possibilities of the design optimization are identified and presented based on the anticipated results. The present analysis is important for the converter design process and can be used for numerical multi-object optimization to further improve the converter design.</abstract>

A MULTILEVEL SWITCHED CAPACITOR DC-DC CONVERTER. AN ANALYSIS OF RESONANT OPERATION CONDITIONS

<abstract xmlns="http://www.w3.org/1999/xhtml"> The aim of the paper is to present a concept of implementation of a space vector modulation (SVM) algorithm, which is used to create alternating current waveforms of changing amplitude and frequency in power inverters. The main goal of the method is to decrease the number of state changes in power transistors. It is realized by utilizing a prediction algorithm and sequences of transistors, which are not common in use. The method requires measurement of inverter output current flow. The prediction algorithm analyzes possible sequences of transistors’ states and choose those which offers smaller switch count. A decrease of about 20% was obtained for the cases tested. This paper presents simulation result for selected driving scenario. The described method decreases the number of state changes in power transistors and therefore it is a potentially good method to considerably decrease energy losses of multilevel inverter-powered drive.</abstract>

A METHOD OF REDUCING SWITCHING LOSSES IN THREE-LEVEL NPC INVERTER

<abstract xmlns="http://www.w3.org/1999/xhtml">The paper presents a linear-quadratic current controller with damped oscillatory terms designed for three-phase grid-tie voltage source converters used in SMES systems and operated under distorted grid voltage conditions. Special emphasis is placed on a synthesis of an anti-windup mechanism to prevent wind-up derived from the oscillatory terms by the use of a new active damping loop based on a simple moving average method. As a consequence, the current feedback gain may be increased without unwanted overshoot and overruns, and performance of the system can be improved.</abstract>

ANTI-WINDUP STRATEGY FOR AN LQ CURRENT CONTROLLER WITH OSCILLATORY TERMS FOR THREE-PHASE GRID-TIE VSCs IN SMES SYSTEMS

<abstract xmlns="http://www.w3.org/1999/xhtml"> The article presents an auto-tuning method of state feedback voltage controller for DC-DC power converter. The penalty matrices employed for calculation of controller’s coefficients were obtained by using nature-inspired artificial bee colony (ABC) optimization algorithm. This overcomes the main drawback of state feedback control related to time-consuming trial-and-error tuning procedure. The optimization algorithm takes into account constraints of selected state and control variables of DC-DC power converter. In order to meet all control objectives (i.e., fast voltage response and chattering-free control signal) an appropriate performance index is proposed. Proper selection of state feedback controller (SFC) coefficients is proven by simulation and experimental tests of DC-DC power converter.</abstract>

APPLICATION OF ARTIFICIAL BEE COLONY ALGORITHM TO AUTO-TUNING OF STATE FEEDBACK CONTROLLER FOR DC-DC POWER CONVERTER

<abstract xmlns="http://www.w3.org/1999/xhtml"> The paper deals with improvement of efficiency of energy storage devices for electric vehicles. The benefits and features of the hybrid energy storage system based on the batteries and ultracapacitors are described. The possible topologies and common schematics of bi-directional DC/DC converters for energy storage are analyzed in terms of efficiency, reliability and battery maintenance. An algorithm for optimization of its parameters is developed, analyzed, shown and explained in detail. The surfaces, which show the dependence between required battery and ultracapacitors’ capacities, energy storage cost and battery discharge ratio are obtained and analyzed. Conclusions are drawn concerning optimization strategy and results of optimization with possible further improvements.</abstract>

OPTIMIZATION OF HYBRID ENERGY STORAGE SYSTEM FOR ELECTRIC VEHICLES

<abstract xmlns="http://www.w3.org/1999/xhtml"> This paper deals with the stability analysis of MRAS current speed estimator in a motoring and regenerating mode. The unstable operating points of the estimator, mainly in a regenerating mode are widely discussed. The expanded version of the estimator MRASCC is proposed to provide its stability in the whole operating range. The new correction coefficients for two analyzed stabilization methods are proposed. Finally, simulation results confirming the theoretical analysis are presented</abstract>

STABILITY ANALYSIS OF MRASSCC SPEED ESTIMATOR IN MOTORING AND REGENERATING MODE

<abstract xmlns="http://www.w3.org/1999/xhtml"> In the paper, an adaptive control MRAS-based structure for nonlinear two-mass system is proposed. The performance of the control structure is supported by additional compensator. After short introduction a mathematical model of the drive system is presented. In the plant, the additional nonlinearities such as friction and mechanical hysteresis are considered. Then the structure of the fuzzy system is shown. Contrary to the majority of papers the controller considered is based on the II type fuzzy sets. Then the simulation tests showing performance of the proposed structure are presented. The drive is tested at different operation points, including low-speed region where friction plays dominant role. A comparison of classical PI controller with antiwindup and the proposed structure is presented. Then laboratory set-up with DC motor is described briefly. Experimental results are included in the paper. It is shown that the torsional vibrations of two-mass system are damped effectively. The impact of the existing delays of system is discussed. A summary is given at the end of the paper.</abstract>

FUZZY ADAPTIVE CONTROL OF NONLINEAR TWO-MASS SYSTEM

<abstract xmlns="http://www.w3.org/1999/xhtml"> Power delivery infrastructures are overstrained and suffer from overaged conditions, not only in the developed, but also in the more industrialized countries. The aim of the smart grid is to provide a more reliable and efficient electric power grid. Condition assessment is an essential and effective part of the reliability for electric grid components; also, it reflects the physical state of the electricity asset in a generation, transmission, distribution, and consumers sides. In this paper, condition assessment of electric grid assets will be discussed and illustrated within the context of smart grid principle. In addition, the proposed condition assessment architecture and the objective of condition assessment for smart grid equipment will be explored and analyzed. Moreover, the potential benefits of such smart system as compared to the traditional power system will be presented. This paper aims to add significant contribution to a smart grid theory.</abstract>

SMART GRID CONDITION ASSESSMENT: CONCEPTS, BENEFITS, AND DEVELOPMENTS

<abstract xmlns="http://www.w3.org/1999/xhtml"> The paper presents a sensorless control of permanent magnet synchronous generator (PMSG) in a variable-speed wind energy conversion system. The system of wind turbine consists of PMSG and back-to-back power converter. The back-to-back converter system is composed of machine side converter (MSC) and grid side converter (GSC). In the control of MSC and GSC the methods of vector control have been applied. For operation of MSC the method of Rotor Field Oriented Control (RFOC) with MPPT algorithm has been used. For estimation of angular rotor position and angular speed the flux linkage estimator with synchronous frame phase locked loop (SF-PLL) has been used. In the control of GSC the method of Voltage Oriented Control (VOC) has been considered. Simulation studies have been carried out in order to evaluate the system of sensorless strategy. The results of simulation studies demonstrate the high efficiency and high accuracy of the sensorless control system considered.</abstract>

PERFORMANCE OF SENSORLESS CONTROL OF PERMANENT MAGNET SYNCHRONOUS GENERATOR IN WIND TURBINE SYSTEM

<abstract xmlns="http://www.w3.org/1999/xhtml"> A review of the literature gives several guidelines for the design of a Permanent Magnet Synchronous Generator (PMSG) for Small Wind Turbines (SWT) applications. This paper presents Finite Element Analysis (FEA) of a Surface Mounted PMSG. Several optimization tests are run in order to yield the lowest Total Harmonic Distortion (THD) and cogging torque with the highest induced voltage. The results of the optimization tests are then utilized to design an initial “optimized” circumferential Internal PMSG. This optimized design is then compared to a non-optimized design, as well as the results of the Surface Mounted PMSG.</abstract>

PARAMETRIC ANALYSIS FOR THE DESIGN OF A 4 POLE RADIAL PERMANENT MAGNET GENERATOR FOR SMALL WIND TURBINES

<abstract xmlns="http://www.w3.org/1999/xhtml"> The article deals with single-phase line start permanent magnet synchronous motor with skewed stator. Constructions of two physical motor models are presented. Results of the motors running properties are analysed.</abstract>

SINGLE-PHASE LINE START PERMANENT MAGNET SYNCHRONOUS MOTOR WITH SKEWED STATOR

Volume 9 (2024): Issue 1 (January 2024)

Volume 8 (2023): Issue 1 (January 2023)

Volume 7 (2022): Issue 1 (January 2022)

Volume 6 (2021): Issue 1 (January 2021)

Volume 5 (2020): Issue 1 (January 2020)

Volume 4 (2019): Issue 1 (June 2019)

Volume 3 (2018): Issue 1 (December 2018)

Volume 2 (2017): Issue 2 (December 2017)

Volume 2 (2017): Issue 1 (June 2017)

Volume 1 (2016): Issue 2 (December 2016)

Volume 1 (2016): Issue 1 (June 2016)

Power Electronics and Drives

Special Section on: Advanced Control Methods of Electrical Machines and Drives  Power Electronics and Drives (PEAD) is an open access, peer-reviewed journal which aims to publish original scientific papers (research and survey papers) on new theoretical developments, novel applications, and case studies regarding advances in power electronics and electrical drive systems. Articles published in our journal cover full scope of power electronics and its applications in electrical drives, renewable energy systems and mechatronic systems. The published articles deal with the following subjects:    power electronic converters;  intelligent control in power electronics and drives;  state variable estimation for AC and DC drives;  diagnostics in power electronics and drive systems;  fault-tolerant control strategies in power electronic converters and drives;  industrial drives, renewable energy systems and smart grid technologies;  power consumption and energy efficiency of converter-fed drives;  electrical machines modeling, simulations and analysis;  motion control, mechatronics;  education issues in power electronics and drives;  other related topics.    The journal is an annual and is published in the open volume system. The basic version of the journal is the electronic version (eISSN: 2543-4292.  The publication in this journal is free of charge.  Power Electronics and Drives is specially oriented to young scientists, PhD students and young Doctors, who can publish (quickly and without any charge) their research results and extended summaries of their PhD dissertations (in this last case the number of pages should be consulted with the Editor-in-Chief).  The journal observes a code of ethics based on academic standards (see for details at the journal web site).  The full texts of articles are freely available from the Power Electronics and Drives web site according to Creative Commons Licence (CC BY-NC-ND) and, since 2018, through the DOAJ database serving the best interests of the scientific community.  Power Electronics and Drives (PEAD) has been published under this title since 2016. It continues the tradition of the journal entitled Scientific Papers of the Institute of Electrical Machines, Drives and Measurements of the Wroclaw University of Technology. Studies and Research, which has been published regularly since 2003 (occasionally from 1969), mainly in Polish. Since 2016 all papers in the whole journal has been published in English.  The journal is published and financed by the Faculty of Electrical Engineering and Department of Electrical Machines, Drives and Measurements at the Wroclaw University of Science and Technology. Since 2019 the journal is published under the patronage of the Electrical Engineering Committee of the Polish Academy of Sciences.  Journal homepage www.ped.pwr.edu.pl  Archiving Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 