Emerging Multiport Electrical Machines and Systems: Past Developments, Current Challenges, and Future Prospects

Distinct from the conventional machines with only one electrical and one mechanical port, electrical machines featuring multiple electrical/mechanical ports (the so-called multiport electrical machines) provide a compact, flexible, and highly efficient manner to convert and/or transfer energies among different ports. This paper attempts to make a comprehensive overview of the existing multiport topologies, from fundamental characteristics to advanced modeling, analysis, and control, with particular emphasis on the extensively investigated brushless doubly fed machines for highly reliable wind turbines and power split devices for hybrid electric vehicles. A qualitative review approach is mainly adopted, but strong efforts are also made to quantitatively highlight the electromagnetic and control performance. Research challenges are identified, and future trends are discussed

A comprehensive review on brushless doubly-fed reluctance machine

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. The Brushless Doubly-Fed Reluctance Machine (BDFRM) has been widely investigated in numerous research studies since it is brushless and cageless and there is no winding on the rotor of this emerging machine. This feature leads to several advantages for this machine in comparison with its induction counterpart, i.e., Brushless Doubly-Fed Induction Machine (BDFIM). Less maintenance, less power losses, and also more reliability are the major advantages of BDFRM compared to BDFIM. The design complexity of its reluctance rotor, as well as flux patterns for indirect connection between the two windings mounted on the stator including power winding and control winding, have restricted the development of this machine technology. In the literature, there is not a comprehensive review of the research studies related to BDFRM. In this paper, the previous research studies are reviewed from different points of view, such as operation, design, control, transient model, dynamic model, power factor, Maximum Power Point Tracking (MPPT), and losses. It is revealed that the BDFRM is still evolving since the theoretical results have shown that this machine operates efficiently if it is well-designed

A comprehensive review on brushless doubly-fed reluctance machine

The Brushless Doubly-Fed Reluctance Machine (BDFRM) has been widely investigated in numerous research studies since it is brushless and cageless and there is no winding on the rotor of this emerging machine. This feature leads to several advantages for this machine in comparison with its induction counterpart, i.e., Brushless Doubly-Fed Induction Machine (BDFIM). Less maintenance, less power losses, and also more reliability are the major advantages of BDFRM compared to BDFIM. The design complexity of its reluctance rotor, as well as flux patterns for indirect connection between the two windings mounted on the stator including power winding and control winding, have restricted the development of this machine technology. In the literature, there is not a comprehensive review of the research studies related to BDFRM. In this paper, the previous research studies are reviewed from different points of view, such as operation, design, control, transient model, dynamic model, power factor, Maximum Power Point Tracking (MPPT), and losses. It is revealed that the BDFRM is still evolving since the theoretical results have shown that this machine operates efficiently if it is well-designed

Fractional kVA Rating PWM Converter Doubly Fed Variable Speed Electric Generator Systems:An Overview in 2020

Variable speed generator systems (VSGs) are at work in the now 600 GW installed wind power plants (parks). Also, they are used as vehicular and on ground stand-alone generators. VSGs imply full kVA rating PWM converters in permanent magnet (PM) or in electrically excited synchronous or in cage rotor inductance generators. But, to reduce cost in absence of PMs at a reasonable initial cost (weight) and efficiency, the fractional kVA PWM converter doubly fed induction generators (DFIG) cover now about 50% of all installed power in wind generators. The present paper reviews recent progress in DFIG and various forms of brushless DFGs (doubly fed generators) characterized in terms of topology, design, performance and advanced control for healthy and faulty load conditions in the hope of inspiring new, hopefully ground breakings, progress for wind and hydro energy conversion and in vehicular and on the ground stand-alone generator applications

A new configuration of dual stator induction generator employing series and shunt capacitors

Doubly-fed induction generators are suitable for systems having limited speed range as the overall control can be carried out by fractionally-rated converters. However, brushes and slip-rings used in these generators reduce system reliability and demand greater maintenance. Dual stator winding induction generator(DSWIG), being brushless, removes this limitation. Two distributed windings are embedded in the stator and the rotor is squirrel-cage. One of the windings is interfaced to an uncontrolled rectifier and the other to a fractionally rated PWM converter. Uncontrolled rectifier degrades the power quality within the generation system. At the same time, reactive power demand in induction generators increases with loading. This work deals with design and control of a standalone dc system based on DSWIG where a combination of passive tuned filter and series capacitor is utilised to address the voltage regulation and power quality issue. Simulation results using MATLAB/Simulink and experimental results (obtained from a laboratory prototype) have been presented, compared and discussed to demonstrate the effectiveness of the proposed alternative

An improved rotor speed observer for standalone brushless doubly-fed induction generator under unbalanced and nonlinear loads

The conventional control methods for brushless doubly-fed induction generator (BDFIG) normally employ mechanical sensors to acquire the information of rotor speed, which brings many disadvantages in the cost, complexity, reliability, and so on. This paper presents an improved rotor speed observer (RSO) for the sensorless operation of a standalone BDFIG, which is based on the power winding (PW) voltage and control winding (CW) current. In order to eliminate the impact of unbalanced and nonlinear loads on the RSO, second-order generalized integrators (SOGIs) and low-pass filters (LPFs) are introduced to pre-filter the PW voltage and CW current, respectively. Through comprehensive parameter design, the response speed of the improved RSO will be not lower than that of the basic RSO with ensuring the filtering effect of these additional filters. In addition, the proposed RSO is independent to machine parameters except the pole pairs. Comprehensive experiments are conducted and results verify the proposed improved RSO applied to the standalone BDFIG. Also, the applicability of the proposed RSO on another dual-electrical-port machine, DFIG, is confirmed by simulation results

A Variable Speed Synchronous Motor Approach for Smart Irrigation using Doubly Fed Induction Motor

Department of Electrical Engineering, College of Engineering, Jazan University, Jizan 45142, Saudi Arabia.Doubly Fed Induction Motor (DFIM) is a popular machine used in variable speed drives, and its ruggedness, reliability and simplicity of speed control make it a suitable candidate for use in smart irrigation systems. This paper studies and evaluates the performance of DFIM at different operating conditions and shows that it can be viewed as a variable speed synchronous motor. The research results reveal that DFIM can be used to control the flow rate of water in irrigation systems, by adjusting the speed of the motor to match the desired flow rate. A mathematical model has been developed to optimize the performance of the DFIM in smart irrigation systems, taking into account the specific conditions of the application. In addition, an experimental setup was built and tested to enhance the theoretical results, which showed good correlation between the theoretical and experimental results. The results of this research demonstrate the potential of using the DFIM in smart irrigation systems to improve the performance and efficiency of irrigation and to provide better control and lower costs

Comparative study between sliding mode control and the vector control of a brushless doubly fed reluctance generator based on wind energy conversion systems

Introduction. Nowadays, global investment in renewable energy sources has been growing intensely. In particular, we mention here that wind source of energy has grown recently. Purpose. Comparative study between sliding mode control and vector control of a brushless doubly fed reluctance generator based on wind energy conversion systems. Methods. This paper deals with conceptual analysis and comparative study of two control techniques of a promising low-cost brushless doubly-fed reluctance generator for variable-speed wind turbine considering maximum power point tracking. This machine's growing interest because of the partially rated power electronics and the high reliability of the brushless design while offering performance competitive to its famous spring counterpart, the doubly-fed induction generator. We are particularly interested in comparing two kinds of control methods. We indicate here the direct vector control based on Proportional-Integral controller and sliding mode controller. Results. Simulation results show the optimized performances of the vector control strategy based on a sliding mode controller. We observe high performances in terms of response time and reference tracking without overshoots through the response characteristics. The decoupling, the stability, and the convergence towards the equilibrium are assured.Вступ. Нині глобальні інвестиції у відновлювані джерела енергії стрімко зростають. Зокрема, звернемо увагу, що останнім часом має місце зростання  вітряних джерел енергії. Мета. Порівняльне дослідження між управлінням ковзним режимом та векторним управлінням безщіткового реактивного генератора з подвійним живленням на основі систем перетворення енергії вітру. Методи. Стаття присвячена концептуальному аналізу та порівняльному дослідженню двох методів управління перспективним недорогим безщітковим реактивним генератором з подвійним живленням для вітряної турбіни зі змінною швидкістю з урахуванням відстеження точки максимальної потужності. Інтерес до цієї машини зростає частково завдяки силовій електроніці, а також високій надійності безщіткової конструкції, яка при цьому пропонує характеристики, порівняні з його загальновідомим пружинним аналогом, індукційним генератором з подвійним живленням. Автори особливо зацікавлені у порівнянні двох видів методів управління. Автори вказують тут на пряме векторне управління на основі пропорційно-інтегрального регулятора та регулятора ковзного режиму. Результати. Результати моделювання показують оптимізовані характеристики векторної стратегії управління на основі контролера ковзного режиму. Спостерігаються високі показники з точки зору часу відгуку та відстеження еталонних значень без перевищення показників відгуку. Розв'язка, стабільність та прагнення до рівноваги гарантуються

Controller Strategy for Open-Winding Brushless Doubly-Fed Wind Power Generator with Common Mode Voltage Elimination

This paper presents the theoretical derivation and implementation of a novel direct power control for open-winding brushless doubly-fed reluctance generator (OW-BDFRG). As one of the promising brushless candidates, the OW-BDFRG is characterized with two stator windings fed by a dual controllable two-level three-phase converters through a common DC bus with common mode voltage elimination. The parameter-free control strategy is designed to obtain maximum power point tracking with variable speed constant frequency (VSCF) for wind energy conversion systems (WECSs). Compared to the traditional three-level converter systems, the DC bus voltage, AC-side voltage and capacity ratings of the proposed converter system are notably high while the reliability, redundancy and fault tolerance are significantly improved. Effectiveness, correctness and robustness of the proposed control strategy and the common mode voltage elimination scheme are evaluated and confirmed through simulation and experimental tests on a 42 kW generator prototype typical for VSCF-WECS