The current study presents an induction heating system design for fiber optics pipes joints. Remote heating methods are probably inconvenient due to non-uniform heat distribution resulting in unreliable joints. The induction heating generates uniform heat distribution which can be achieved by proper designing of inductive heating coil, and power system inverter that drives the induction system. Two different shaped open jaw type heating coils were designed i.e open claw type coil (OCTC) and curved spiral rectangular coil (CSRC). The coils were designed in COMSOL simulation software to check the coil and workpiece behaviours. These coil designs were then wounded by hand and resistance and inductance of each coil were measured. The OCTC is a short loop coil, having small inductance while the CSRC has a long loop so its inductance is high. CSRC design was selected in the current application. The CSRC inductance was calculated through modified Wheeler formula and current sheet approximation. To design the power inverter, firstly the power density of heating material i.e workpiece was calculated. Then the thermal losses of the coil were calculated, these losses were due to skin effect and proximity effect; and switch losses due to drain to source resistance(RDS) of Mosfets were estimated. The Mazzilli inverter was proposed for power system inverter design which works as a parallel resonant circuit. It was designed in Mandi simulation software and then implemented on hardware. Theoretical results were compared with the practical measurements through Matlab software. Coil efficiency, power inverter efficiency and overall system efficiency were also calculated. This induction heating method for fiber optics joints is repeatable, consistent, generates uniform heat and is more convenient for site-specific heat generated on workpiece. It is portable, user friendly and environmental friendly as well.

The great tunability of structure and electronic properties of π-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided. Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here. Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination. Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.

Denna studie har genomförts i form av en undersökning med 25 respondenter. Arbetet harsyftat till att fackmän inom belysningsbranschen samt privatpersoner och intressenter ska fåen indikation på hur människan uppfattar ljuset från fasdimrade LED-ljuskällor i privata hem.Studien har studerat två frågeställningar gällande människans upplevelse av flimmer blandannat hur känslig människan är för flimmer hos en ljusreglerad LED-ljuskälla innan detuppfattas som obekvämt. Vetenskaplig litteratur har använts för att få en förståelse och djuparekunskap kring problematiken gällande människans hälsopåverkan vid exponering av flimmer,samt vilka riktlinjer och möjliga tillvägagångssätt som finns för att lösa denna problematik. Föratt ta reda på hur väl människan uppfattar flimmer samt hur upplevelsen av obekvämlighetenpåverkas har en enkät tagits fram till studien. Undersökningen konstaterar att människoruppfattar flimmer i olika mängd, trots frekvenser över 90Hertz (Hz). Genom data från digitalamätningar och inhämtad empiri från arbetets undersökningsstudie kan man konstatera att detinte enbart är frekvensnivån som påverkar människans uppfattning av flimmer, utan ävenljuskällans andel flimmerprocent. Ett samband mellan upplevd obekvämlighet och flimmer kananas, men inte fastslås som ett tydligt resultat. Arbetet avgränsades genom att undersökningenenbart utfördes under en kortare period med ett färre antal respondenter. / This study has been carried out in the form of a survey with 25 respondents. The work has aimedto give professionals and individuals an indication of how people perceive the light from phasedimmedLED light sources in private homes. The study has investigated two issues regardingthe human experience of flicker, and how sensitive human beings are to flicker from a phasedimmedLED light source before it will be perceived as inconvenient. Scientific literature hasbeen reviewed to gain an understanding and deeper knowledge about the impact of flicker onhuman health, and which guidelines and possible approaches there are to solve the problem. Asurvey has been developed to find out if flicker is perceived by humans, and how the perceptionof inconvenience is experienced. The study found out that people perceive flicker differently,despite measured frequencies above 90 Hertz (Hz). Through data from digital measurementsand acquired empirical evidence from the study’s results, it is not only the frequency level thataffects humans perception of flicker, but also the percentage of light emitted from the lightsource. A correlation between perceived inconvenience and flicker can be noted, but notdetermined as a clear result. The work was limited by only investigating a small population ofrespondents over a short period of time.

Ljusbommar/ljusridåer är ett vanligt säkerhetsskydd på dagens industrier, där arbete görs vid rörliga delar.  Det ställs höga säkerhetskrav på ljusbommar/ljusridåer. När ett skydd bryts behöver det återställas och detta görs vanligtvis med en tryckknapp. Detta system medför ett hinder i situationer där truckar används, eftersom att arbetaren behöver kliva ur trucken för att göra återställning av skyddet. Ett trådlöst system av återställningen är lösningen på problemet, men det ställs krav på ett sådant system. Ett öppet lasersystem har valts att undersökas om det skulle kunna uppfylla de krav som ställs. För att testa om ett öppet lasersystem skulle kunna användas togs en prototyp fram. Prototypen bestod av en lasermodul som sändare och en solcell som mottagare. Systemet styrdes av två stycken mikrokontrollers som kommunicerade via UART. Prototypen testades för hur stabilt systemet var mot ljusstörningar och inom vilket område det var begränsat. Det visade sig att den prototyp som tagits fram inte fungerade när störningsljus med frekvenser i sig belyste mottagaren. Prototypens områdesbegränsning visade sig var alldeles för stor. Slutsatsen av undersökningen var att det är teoretiskt möjligt att byta ut knappen mot ett öppet lasersystem, dock inte med den prototyp som togs fram. Det behövs istället en prototyp som måste bearbetas mer för att kunna uppfylla de krav som skulle ställas för trådlösåterställning av ljusbommar/ljusridåer. / Light beams / light curtains are a common safety guard on today's industries, where work is done on moving parts. High safety requirements are imposed on light beams / light curtains. When a protection is broken, it needs to be reset and this is usually done with a pushbutton. This system in which truckers are used, a problem arises, because the worker needs to get out of the truck to repair the guard. A wireless recovery system is the solution to the problem, but it needs to meet high standards. An open laser system has been chosen to be investigated if it could meet the requirements. To test if an open laser system could be used, a prototype was taken. The prototype consists of a laser module as a transmitter and a solar cell as a receiver. The system is controlled by two microcontrollers communicating via UART. The prototype was tested for how stable the system was and in which area it was limited. It turned out that the prototype produced did not work when the interference light with frequencies in itself illuminated the receiver. The prototype area restriction proved to be too wide in the area. The conclusion of the survey was that it is theoretically possible to replace the button with an open laser system. However, not with the prototype that was presented, but with a prototype that has to be processed more to meet the requirements for wireless reset of light bombs / light curtains.

Contactless automatic identification procedures which are called RFID systems (Radio-frequency Identification) have become very popular in recent years for transferring power and data. With the development of RFID technology, the demand of easy transmitting of short data packages has made NFC (Near-field Communication) technology wildly used especially in mobile applications. The communication between a mobile and a tag is achieved through a magnetic field generated by the mobile’s NFC interface. In order to get a maximal power transmission, the tag circuit is designed to operate at the resonance frequency of 13.56 MHz, which is equal to the operation frequency of the mobile’s NFC interface. As mutual inductances provided by different kinds of mobiles exist divergence, optimal power transfer cannot be reached every time. This thesis focuses on the optimization of power transfer during the communications between tags and mobiles with uncertain NFC coils. By incorporating a self-tuning parallel variable capacitance compensation circuitry the resonance frequency of an NFC tag circuit can be self-tuned to 13.56 MHz to ensure an optimal power transmission. This thesis presents both theoretical and experimental analysis of this improved self-tuning NFC circuitry in detail and demonstrates that by digitally tuning a parallel capacitor circuit, the energy transferred to an NFC tag can be optimized when facing different kinds of NFC-enabled mobile phones.

The increasing penetration of wind power into the power system dominated by variable-speed wind turbines among the installed wind turbines will require further development of control methods. Power electronic converters are widely used to improve power quality in conjunction with the integration of variable speed wind turbines into the grid. In this thesis, a detailed model of the Predictive Current Control (PCC) method will be descripts for the purpose of control of the grid-connected converter. The injected active and reactive power to the grid will be controlled to track their reference value. The PCC model predicts the future grid current by using a discrete-time model of the system for all possible voltage vectors generated by the inverter. The voltage vector that minimizes the current error at the next sampling time will be selected and the corresponding switching state will be the optimal one. The PCC is implemented in Matlab/Simulink and simulation results are presented.

Power to X, hereinafter PtX, is a conversion of electricity into some kind of energy carrier, such as gas or liquid. The purpose of the technique is often to store “excess” energy from renewable energy sources, usually wind power, in order to use it later. One aspect ofPtX is Power to Gas, hereinafter PtG, which involves the conversion of electricity often by the use of an electrolyser into a gaseous energy carrier, such as hydrogen or methane. The technology is a promising strategy for balancing the electricity supply in countries that striveto have near zero carbon dioxide emissions and have to rely on renewable energy sources. Another part of PtX that has received more attention lately and that may be important in the future, with more fluctuating electricity prices due to a larger share of renewableenergy in the energy systems, is the technique Power to gas to power, PtGtP. In PtGtP electrical energy, often with the help of anelectrolyser, is converted and stored in a gaseous energy carrier and later on when there is an electricity shortage it is converted backinto electrical energy through fuel cells. PtGtP can therefore be seenas a further development of PtG. The purpose of the study is therefore to investigate the potential forPtX, more specifically PtG and PtGtP in Sweden in terms ofprofitability. PtG was investigated considering production of hydrogenand methane where the hydrogen was sold as fuel for vehicles and the methane was injected into the gas distribution network in Stockholm.The methane production also results in surplus heat which was injected into the district heating network. To investigate this, a qualitativecase study was carried out on two hypothetical facilities. One fromthe Swedish company Euromekanik, that produces hydrogen and one from the German company Electrochaea that produces methane. Euromekanik’s facility was also used for the PtGtP application. The results weremainly based on the electricity prices of 2019. However, electricityprices for 2017, 2018 as well as more volatile electricity prices havebeen examined. Simulations of the input- and output flows in thefacilities have been performed in MATLAB and profitabilitycalculations have been performed using the net present value methodand the profitability index. A sensitivity analysis was conducted inwhich the values of the most important parameters were varied. The results regarding PtG in this study show that the idea ofproduction should take place when the electricity prices are low canbe rejected. The results also show that the conversion of hydrogeninto methane decreases the profitability. Running the PtG plant allhours of the year and producing hydrogen is therefore the mostprofitable design of the plant, even though this set-up still resultsin a negative net present value of approximately 24 MSEK after 20years. The result from the investigation of PtGtP shows that due tothe low system efficiency, the electricity sold back to the grid needsto have a price of 5000-6000 SEK/MWh for the plant to break-even when purchasing electricity a fourth of the hours of the year with thelowest electricity price. With the pattern and prices on the Swedish electricity market today this technique will not be profitable.However, both PtG and PtGtP will most likely have another value than solely the economic profitability in terms of energy storage andsystem balancing functions, though that has not been examined in this thesis.

This thesis presents the stability analysis of an Electric Road System (ERS), which is often abbreviated as eHighway, used for the electrification of the hybrid vehicle. The overall system modelling of the ERS, starting from the sub-station to the critical part of the Scania hybrid truck is performed in the MATLAB Simulink environment. The ERS consists of an overhead catenary line (OCL), where vehicles are electrified by using a pantograph mounted over the vehicle. The stability analysis of the power supply of the overhead line is done by taking into account several aspects of the system. The simulation results are validated with the real test track measurements and the deviations are shown. The frequency response of the system is considered to measure the stability margin. The resonance conditions are clarified and essential variable choke is proposed to damp them out. Also the harmonic components injected from the vehicle side, that are in the closer range of the resonance, are figured out and filtered. When multiple vehicles are electrified from the same catenary line, then there are interferences in between the vehicles. These disturbances both to the vehicles and the overhead power supply system are presented in the time domain. Finally, the results are shown to demonstrate the effectiveness of the variable choke to increase the stability margin in the overhead supply system. In the frequency domain results, it has shown that the resonance is shifted out of the system operating frequency. In the time domain results, it has shown that the high amplitude of the current and voltage signals are sufficiently damped out by variable choke implementation.

This master thesis report details the process of developing a simulation platform for radio transceivers with a focus on analog receiver front end system design. The platform was implemented in the National Instruments VSS environment for the company Ericsson AB.

Discrete silicon carbide (SiC) power devices have unique characteristics that outpace those of silicon (Si) counterparts. The improved physical features have provided better faster switching, greater current densities, lower on-resistance, and temperature performances. However, there is lack of suitable commercial gate drivers that are compatible for high-voltage, and high-speed devices. There has been a great research effort required for the advancement of gate drivers for high voltage SiC transistors. A drive circuit for a SiC MOSFET needs to be optimized in normal operation to give best efficiency and same drive circuit should secure the MOSFET under unsuitable conditions. To ensure the rapid switching of these advanced SiC MOSFETs, a gate driver capable of providing the high current capability is required. In this work, three different high-power-density, high-speed, and high-noise-immunity gate driver modules for 10 kV SiC MOSFET were built and optimized.  Double-pulse test was developed for the dynamic characterization of SiC MOSFETs and gate drivers. This setup provided clean measurements of DUT voltage and current under well-defined conditions and correlated to simulation results. Designed gate drivers have thoroughly investigated to test and compare it with our future design. The influential parameters such as dV/dt, dI/dt, and gate driving capability of gate driver were adjusted according to the requirements. The short circuit protection test was performed to check the reliability of driver modules in worst conditions. Furthermore, a DC-DC converter was designed and tested with the advanced gate drivers. The driver modules were tested in designed converter under different load conditions and influential parameters were successfully demonstrated. The driver modules effectively helped in reducing the EMI and switching losses. These designed gate drivers and prototype converter provide all the attractive features and can be widely implemented in industrial applications for energy efficient systems.