Over the years, an increase in the traffic of electric and hybrid electric vehicles and vehicles ... more Over the years, an increase in the traffic of electric and hybrid electric vehicles and vehicles with hydrogen cells is being observed, while at the same time, self-driving cars are appearing as a modern trend in transportation. As the years pass, their equipment will evolve. So, considering the progress in vehicle equipment over the years, additional technological innovations and applications should be proposed in the near future. Having that in mind, an analytical review of the progress of equipment in electromobility and autonomous driving is performed in this paper. The outcomes of this review comprise hints for additional complementary technological innovations, applications, and operating constraints along with proposals for materials, suggestions and tips for the future. The aforementioned hints and tips aim to help in securing proper operation of each vehicle part and charging equipment in the future, and make driving safer in the future. Finally, this review paper concludes...
The electric machines are the elements most used at an industry level, and they represent the maj... more The electric machines are the elements most used at an industry level, and they represent the major power consumption of the productive processes. Particularly speaking, among all electric machines, the motors and their drives play a key role since they literally allow the motion interchange in the industrial processes; it could be said that they are the medullar column for moving the rest of the mechanical parts. Hence, their proper operation must be guaranteed in order to raise, as much as possible, their efficiency, and, as consequence, bring out the economic benefits. This review presents a general overview of the reported works that address the efficiency topic in motors and drives and in the power quality of the electric grid. This study speaks about the relationship existing between the motors and drives that induces electric disturbances into the grid, affecting its power quality, and also how these power disturbances present in the electrical network adversely affect, in tu...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
2020 International Conference on Electrical Machines (ICEM), 2020
In this study, a current monitoring approach is proposed for Hall-effect position sensor-based Br... more In this study, a current monitoring approach is proposed for Hall-effect position sensor-based Brushless DC motor drives to detect and mitigate the inherited defect of the misaligned position sensors. Considering a single sensor approach, DC-link current monitoring and frequency-domain analysis are exploited for the unbalanced system operation diagnosis and commutation signal reconstruction with a minimum error. Thus, both relative and absolute misalignment errors are investigated. The second harmonic component of the DC-link current frequency spectrum is evaluated as a potential fault signature of the unbalanced system operation due to single, double, and triple defective configurations of the position sensors. In addition, the Goertzel algorithm is exploited for the implementation of the harmonic analysis in a narrow frequency band, while a filtering stage, based on wavelet decomposition, is proposed for the initial characterization of reference sensor. Finally, DC-link current third harmonic component is proposed for the absolute error estimation.
2016 IEEE Industry Applications Society Annual Meeting, 2016
The present study deals with the combined operation of a doubly-fed induction generator (DFIG) wi... more The present study deals with the combined operation of a doubly-fed induction generator (DFIG) with sensorless based control, which is common to wind energy conversion systems (WECSs) and an energy storage system (ESS). The scope of this paper is to present a coordinative control system to enhance the DFIG ability to recover from a fault condition. Despite the numerous benefits of the sensorless control, this approach suffers from high sensitivity to the dynamics effects. Herein, a three-phase short-circuit is considered as a significant and most common dynamic effect. The newly protection method - combined with the classical protection methods, i.e. crowbar, breakers - refers to a battery based energy storage system connected to the DC link of the back to back converter through a fuzzy-controlled bidirectional DC/DC converter. The aforementioned configuration aims to mitigate the DC bus voltage fluctuations during grid faults and subsequently to ensure the seamless operation of the...
Epoxy resin constitutes a vital insulating element for electrical machine insulation. The present... more Epoxy resin constitutes a vital insulating element for electrical machine insulation. The present paper deals with the phenomenon of flashover in nanocomposite epoxy resin (with TiO2 nanoparticles) under the influence of uniform electric fields. As is known, water droplets on insulating surfaces may cause dry zones, local discharges and eventually arcs. Several parameters, affecting the flashover voltage, were investigated, such as water conductivity, droplet volume, number of droplets and the position of the droplets on the samples w.r.t. the electrodes. All the aforementioned parameters affect the flashover voltage. The flashover voltage changes with the percentage of nanoparticles in epoxy resin. It seems that there is an optimum percentage of nanoparticles added to epoxy resin, which gives a higher flashover voltage. Furthermore, comparisons between pure epoxy resin and epoxy resin with nanoparticles showed that the latter presented higher flashover voltages than the former.
Electric vehicles (EVs) have become widespread during the last decade because of the distinct adv... more Electric vehicles (EVs) have become widespread during the last decade because of the distinct advantages they offer compared to the conventional ones. However, the increased penetration of EVs in the global transportation market has led increased electricity demands, which is expected to affect the operation of energy distribution systems. In the present paper, a demonstration about the effects of uncontrolled EVs charging in a case study low voltage (LV) network is demonstrated and a fuzzy energy management strategy for the coordination of EV charging in LV networks is presented, by including the distance of the EVs from the transformers in the fuzzy management systems for the first time. The Institute of Electrical and Electronics Engineers (IEEE) European Test Feeder is used as a case study low voltage distribution grid. In particular, the developed system configuration takes into consideration the architecture of the grid, the ampacities of the lines and the voltages at the syst...
Advances in experimental medicine and biology, 2017
Today, the advanced technology is a part of the everyday's life. As a result, most of the app... more Today, the advanced technology is a part of the everyday's life. As a result, most of the applications used require a more complex system in order to achieve a better performance. These systems have a mathematic background indicating the need of a better mathematical tool to increase the reliability of them. One of the most significant problems coming up against these systems is undoubtedly the non-linearity of the equations governing them. Herein, a linearization method is proposed and studied through intelligent control. The transformation of a non-linear system into a linear is based on fuzzy logic and more specifically on Takagi-Sugeno technique. Firstly, it is analyzed in a theoretical level followed by two examples. The fuzzy model was developed through Matlab program. Finally, the efficiency of the above method was investigated setting up various values for the under study variables and comparing the results of them with the "actual" ones. The square error metho...
This paper proposes a method to diagnose the aging of model stator bars. Experiments have been pe... more This paper proposes a method to diagnose the aging of model stator bars. Experiments have been performed in such bars, and the maximum partial discharge has been recorded as the applied voltage increases and then decreases. The resulting ldquohysteresisrdquo curve shows whether the stator bar is in a ldquogoodrdquo or ldquobadrdquo state. It is shown that the aging of the
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, 2019
Nowadays, microgrids and nanogrids are becoming more and more popular since they facilitate the i... more Nowadays, microgrids and nanogrids are becoming more and more popular since they facilitate the integration of Distributed Generation (DG) in the utility grid. In the meantime, the technology advancements in power electronics and energy storage systems have increased the interest in Electric Vehicles (EVs). The scope of this study is to describe a design methodology of a DC nanogrid that consists of a photovoltaic system and an EV battery. The design procedure of the bidirectional DC-charger of the EV batteries and the three-phase inverter that are included in the configuration takes into consideration all the requirements of the Vehicle-to-Grid (V2G) technology. The nanogrid was modeled via Matlab/Simulink. The simulation results verify the effectiveness of the proposed configuration.
2017 IEEE International Conference on Environment and Electrical Engineering and 2017 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2017
Partial discharges (PD) are a symptom and at the same time the result of the deterioration and th... more Partial discharges (PD) are a symptom and at the same time the result of the deterioration and the aging of an electrical machine's insulation. Based on experiments the flashover voltage of epoxy resin samples in relation to humidity was studied and the results are discussed.
Over the years, an increase in the traffic of electric and hybrid electric vehicles and vehicles ... more Over the years, an increase in the traffic of electric and hybrid electric vehicles and vehicles with hydrogen cells is being observed, while at the same time, self-driving cars are appearing as a modern trend in transportation. As the years pass, their equipment will evolve. So, considering the progress in vehicle equipment over the years, additional technological innovations and applications should be proposed in the near future. Having that in mind, an analytical review of the progress of equipment in electromobility and autonomous driving is performed in this paper. The outcomes of this review comprise hints for additional complementary technological innovations, applications, and operating constraints along with proposals for materials, suggestions and tips for the future. The aforementioned hints and tips aim to help in securing proper operation of each vehicle part and charging equipment in the future, and make driving safer in the future. Finally, this review paper concludes...
The electric machines are the elements most used at an industry level, and they represent the maj... more The electric machines are the elements most used at an industry level, and they represent the major power consumption of the productive processes. Particularly speaking, among all electric machines, the motors and their drives play a key role since they literally allow the motion interchange in the industrial processes; it could be said that they are the medullar column for moving the rest of the mechanical parts. Hence, their proper operation must be guaranteed in order to raise, as much as possible, their efficiency, and, as consequence, bring out the economic benefits. This review presents a general overview of the reported works that address the efficiency topic in motors and drives and in the power quality of the electric grid. This study speaks about the relationship existing between the motors and drives that induces electric disturbances into the grid, affecting its power quality, and also how these power disturbances present in the electrical network adversely affect, in tu...
All in-text references underlined in blue are linked to publications on ResearchGate, letting you... more All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
2020 International Conference on Electrical Machines (ICEM), 2020
In this study, a current monitoring approach is proposed for Hall-effect position sensor-based Br... more In this study, a current monitoring approach is proposed for Hall-effect position sensor-based Brushless DC motor drives to detect and mitigate the inherited defect of the misaligned position sensors. Considering a single sensor approach, DC-link current monitoring and frequency-domain analysis are exploited for the unbalanced system operation diagnosis and commutation signal reconstruction with a minimum error. Thus, both relative and absolute misalignment errors are investigated. The second harmonic component of the DC-link current frequency spectrum is evaluated as a potential fault signature of the unbalanced system operation due to single, double, and triple defective configurations of the position sensors. In addition, the Goertzel algorithm is exploited for the implementation of the harmonic analysis in a narrow frequency band, while a filtering stage, based on wavelet decomposition, is proposed for the initial characterization of reference sensor. Finally, DC-link current third harmonic component is proposed for the absolute error estimation.
2016 IEEE Industry Applications Society Annual Meeting, 2016
The present study deals with the combined operation of a doubly-fed induction generator (DFIG) wi... more The present study deals with the combined operation of a doubly-fed induction generator (DFIG) with sensorless based control, which is common to wind energy conversion systems (WECSs) and an energy storage system (ESS). The scope of this paper is to present a coordinative control system to enhance the DFIG ability to recover from a fault condition. Despite the numerous benefits of the sensorless control, this approach suffers from high sensitivity to the dynamics effects. Herein, a three-phase short-circuit is considered as a significant and most common dynamic effect. The newly protection method - combined with the classical protection methods, i.e. crowbar, breakers - refers to a battery based energy storage system connected to the DC link of the back to back converter through a fuzzy-controlled bidirectional DC/DC converter. The aforementioned configuration aims to mitigate the DC bus voltage fluctuations during grid faults and subsequently to ensure the seamless operation of the...
Epoxy resin constitutes a vital insulating element for electrical machine insulation. The present... more Epoxy resin constitutes a vital insulating element for electrical machine insulation. The present paper deals with the phenomenon of flashover in nanocomposite epoxy resin (with TiO2 nanoparticles) under the influence of uniform electric fields. As is known, water droplets on insulating surfaces may cause dry zones, local discharges and eventually arcs. Several parameters, affecting the flashover voltage, were investigated, such as water conductivity, droplet volume, number of droplets and the position of the droplets on the samples w.r.t. the electrodes. All the aforementioned parameters affect the flashover voltage. The flashover voltage changes with the percentage of nanoparticles in epoxy resin. It seems that there is an optimum percentage of nanoparticles added to epoxy resin, which gives a higher flashover voltage. Furthermore, comparisons between pure epoxy resin and epoxy resin with nanoparticles showed that the latter presented higher flashover voltages than the former.
Electric vehicles (EVs) have become widespread during the last decade because of the distinct adv... more Electric vehicles (EVs) have become widespread during the last decade because of the distinct advantages they offer compared to the conventional ones. However, the increased penetration of EVs in the global transportation market has led increased electricity demands, which is expected to affect the operation of energy distribution systems. In the present paper, a demonstration about the effects of uncontrolled EVs charging in a case study low voltage (LV) network is demonstrated and a fuzzy energy management strategy for the coordination of EV charging in LV networks is presented, by including the distance of the EVs from the transformers in the fuzzy management systems for the first time. The Institute of Electrical and Electronics Engineers (IEEE) European Test Feeder is used as a case study low voltage distribution grid. In particular, the developed system configuration takes into consideration the architecture of the grid, the ampacities of the lines and the voltages at the syst...
Advances in experimental medicine and biology, 2017
Today, the advanced technology is a part of the everyday's life. As a result, most of the app... more Today, the advanced technology is a part of the everyday's life. As a result, most of the applications used require a more complex system in order to achieve a better performance. These systems have a mathematic background indicating the need of a better mathematical tool to increase the reliability of them. One of the most significant problems coming up against these systems is undoubtedly the non-linearity of the equations governing them. Herein, a linearization method is proposed and studied through intelligent control. The transformation of a non-linear system into a linear is based on fuzzy logic and more specifically on Takagi-Sugeno technique. Firstly, it is analyzed in a theoretical level followed by two examples. The fuzzy model was developed through Matlab program. Finally, the efficiency of the above method was investigated setting up various values for the under study variables and comparing the results of them with the "actual" ones. The square error metho...
This paper proposes a method to diagnose the aging of model stator bars. Experiments have been pe... more This paper proposes a method to diagnose the aging of model stator bars. Experiments have been performed in such bars, and the maximum partial discharge has been recorded as the applied voltage increases and then decreases. The resulting ldquohysteresisrdquo curve shows whether the stator bar is in a ldquogoodrdquo or ldquobadrdquo state. It is shown that the aging of the
IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society, 2019
Nowadays, microgrids and nanogrids are becoming more and more popular since they facilitate the i... more Nowadays, microgrids and nanogrids are becoming more and more popular since they facilitate the integration of Distributed Generation (DG) in the utility grid. In the meantime, the technology advancements in power electronics and energy storage systems have increased the interest in Electric Vehicles (EVs). The scope of this study is to describe a design methodology of a DC nanogrid that consists of a photovoltaic system and an EV battery. The design procedure of the bidirectional DC-charger of the EV batteries and the three-phase inverter that are included in the configuration takes into consideration all the requirements of the Vehicle-to-Grid (V2G) technology. The nanogrid was modeled via Matlab/Simulink. The simulation results verify the effectiveness of the proposed configuration.
2017 IEEE International Conference on Environment and Electrical Engineering and 2017 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2017
Partial discharges (PD) are a symptom and at the same time the result of the deterioration and th... more Partial discharges (PD) are a symptom and at the same time the result of the deterioration and the aging of an electrical machine's insulation. Based on experiments the flashover voltage of epoxy resin samples in relation to humidity was studied and the results are discussed.
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Papers by Athanasios Karlis