Abstract

Energy system has been going through a revolutionary transformation over the past years. The rising adoption of unpredictable, decentralised renewable energy sources is said to accelerate in the next decades. Variable renewable electricity production in many different locations, can often lead to unexpected and unsought for deviations of gird parameters: frequency and voltage. unsought for devi ations of gird parameters: frequency and voltage, or even congestion of the system. Thus, decentralised electricity system would have a surpassing need of flexibility of the system, which could assure proper regulation of frequency and voltage when needed. The consumption of electricity is also viable and not utterly predictable. To avoid the congestion of electrical grid the demand side response concept has been sprouting. One of the new concepts of demand side response measures is aggregation. Aggregated load regulation envisions gathering and managing numerous small loads, in a way that could stop deviations of frequency and voltage in the system or avoid congestion , without bringing any inconveniences for the owner of the load. EVs while charging, are t hose loads that are often mentioned as aggragatable. With the emerge of massive adoption of Electric Vehicle, secondary uses of it are being questioned. One of them is the idea of balancing the ever changing frequency and voltage in the grid with usage of flexibility created by creating various patterns of charging an electric vehicle. This process is known as Smart Charging. This study integrate s previously mentioned innovations of energy system and analyse the potential of aggregation of electric vehicle s for the purpose of providing flexibility to the electricity system. The thesis will be a technical and economic analysis of the possibility of unlocking this potential in Europe. The regulatory and technical aspects of possible demand side response aggr egation development are presented in the thesis , along with the analysis of Electric Vehicles market and its potential. Thereafter, one exemplary market is analysed further, through developed optimisation model, which allows to assess the value of most imp ortant factors for the aggregator. Three key changing variables are considered in the scheme of charge, those are : the targeted group of clients, the power of the used charger, and the scheme of charging. To assess the importance of those variables the stream of revenues as well as the environmental benefits in the form of potential CO 2 emissions savings are analysed against the variables. E 2 F easibility and market assessment for EV scheduling and aggregation in E uropean countries 2 The major aim and finding of this thesis is to answer the question whether it is plausible to profitab ly develop grid balancing with smart charging of electric vehicles in European Free Trade Association membership countries. The reader will only get to know the answer to that question after flicking through the pages of this paper

Abstract

This research report is structured in 7 Chapters which pretend to guide the reader from a general point of view of Wireless Power Transfer (WPT) and its applications, to a deep and better understanding of Inductive Power Transfer (IPT) applied to Wireless Electric Vehicle Charging Systems (WEVCS). To do so, after the background introduction, each chapter studies a different part of the IPT system, ending up with the analysis of the simulation and hardware results.The background introduction is shown in Chapter 3, and explainshow energy started to be transferred wirelessly along history, classifying WPT into near-field (NF) and far-field (FF). Focus has been placed in NF WPT explaining inductive, capacitive and resonant variants, as the main existing forms of transferring energy through electromagnetic waves. Additionally, applications of NF have been commented concerning the charge of portable devices, electric transportation or biomedical implants. Wireless chargersfor electric vehicles are within the scope of this report. Hence,a detailed explanation of the two main topologies, static wireless charging (SWC) and dynamic wireless charging (DWC) has been given. To finish the review, information regarding a safe application following the current regulations has been mentioned as long as the principal standards that aimto smooththe path towards an early adaptation of IPT technology for EV charging purposes.In Chapter 4,IPT has been demonstratedwith mathematical expressions so as to be able to model thesystem that hereinafter will be simulated and validated. It starts with the formulation to get the relationship between the flux linkage and the currents, followed by an equivalent circuit representation. An initial analysis of the results can bealready obtained at this point.Howeverto increase the coupler’s efficiency a compensation network is added to either the equivalent circuit and the previous equations. The last part of the chapter is the design process of the coupler following an iterated procedure, where based on the charging specifications, by fixing some desired parameters the transmitter and receiver coils can be developed. Chapter 5explains the power electronics converters, essential in this system to increase the frequency up to de kHz range and reduce the size of its passive components. The converters used in the simulation and the hardware implementation are a DC/AC H-bridge inverter with Silicon Carbide (SiC) MOSFETs due to the high switching frequency intended to be used, and a diode bridge rectifier to turn the AC into DC and be able to charge thevehicle’s battery. Both converters have been simulated, first separately and then together to see the overall performance. Finally, a low pass filter has been added to smooth the ripple of the voltage and current of the load.The final components ordered have been listed and explained in Chapter 6, using the real values of the parameters given by the supplier to calculate and simulate the results. The results have been put together in Chapter 7, on theone hand the simulation results obtained with Matlab/Simulink and on the other hand the tests carried through with the hardware in the laboratory. The 4Reportgoal of this last chapter is to validate the theoretical results. An intermediate stage is the simulation, which is crucial to learn the performance of the system in non-common situations. That is why several cases have been studied, varying the position of the coils in the three axis, and analysinghow the misalignment affects to the efficiency. This study is important, for dynamic charging testing is oneofthe targets set for this project and future work. Outgoing

Abstract

continuously growing penetration of electric (EV) and hybrid electric (HEV) vehicles, reinforced by the need for increased energy savings, drove the research towards power electronic components with superior material properties. Wide-bandgap (WBG) power semiconductor materials such as Silicon Carbide (SiC) offer significant improvements in power converter’s performance as they allow higher operating voltage, higher switching frequency and higher maximum operating temperature. As a consequence, it is expected to be utilized in traction DC-DC converters where high efficiency, high power density and lower cooling requirements are desired while, simultaneously, achieving significa nt reductions in the total weight and volume of the powertrain. The improved features introduced by SiC MOSFETs on DC-DC converter topologies employed in EVs and HEVs are investigated and experimentally verified. Initially, a non-isolated half-bridge DC-DC converter topology is designed with operating principles that correspond to a converter found on energy management systems of HEVs or fuel cell vehicles. The operating principle of the converter is presented and the bi-directional flow of energy aspect is explained. Subsequently, the design has been modelled and evaluated on a simulation software that considered the operating stages of the converter by also accounting for the gate driving circuit and the predefined cooling requirements. Finally, a test prototype was built in custom-made printed circuit board (PCB) and validated in terms of reliable operation and circuit efficiency. The benefits from utilizing SiC power semiconductors are presented under constant 24 V loading conditions and 80 kHz switching frequency. A constant voltage was maintained through automatically modulating the gate driving signal, whereas an efficiency of around 96% was achieved due to fast switching times introduced by SiC MOSFETs and thus the reduced switching losses. The efficie ncy of the system is dependable on the MOSFET operating performance and therefore an exposure of the transistors in environmental conditions was considered for each individual SiC MOSFET provided by different suppliers. Significant attention has been paid to rapid temperature change, extreme humidity, mechanical vibration and accelerated ageing tests that aim to address possible degradation and defects in the SiC material. The effect of the testing process was examined in component-level, by assessing the electrical characteristics of the SiC MOSFETs, as well as in converter-level by evaluating potential efficiency reductions and operating flaws. Finally, verification of the conditions under which each individual change occurred is of equal importance for prospective improvements in the transistor and converter alike.

Abstract

This work seeks to determine the potentials of a Demand Aggregator into the Demand Response scheme. The authors describe and validate the optimization technique used by the Aggregator to enable demand flexibility in domestic microgrid premises. The microgrid is comprised of Distributed Generation and shiftable load devices. By applying a monetary incentive signal in the microgrid's Energy Management System, the Aggregator empowers a change in the load profile, which signifies the potential of this concept in future electricity market and grid applications.

Abstract

This paper is a summary of the debate that took place in the round tables: - What is slowing down the application of SRM drivesfor road vehicle electrification? - Where should research and development focus toboost application of SRM drives to E-traction? These round tables were the second part of the Workshop SRM an alternative for E-Traction held at the EPSEVG, on February 2, 2018.