The master’s thesis was focused on the determination of persistent organic pollutants, namely polychlorinated biphenyls were detected (PCB 28, 52, 101, 118, 138, 153 and 180) and organochlorine pesticides. A total of 31 were evaluated contamination of organochlorine compounds. The level of contamination by organic pollutants were detected in 20 samples, 9 samples were sediments from the river Jevišovka, which is located in the South Moravia and 11 samples represented arable soil samples and were collected in the vicinity of this river. In the theoretical part are characterized both groups of substances, their fate in the environment and negative effects on living organisms. The experimental part focuses on the sampling procedures and processing for analysis by gas chromatography. There is described a complex analytical process involving the three extraction methods (accelerated solvent extraction, microwave extraction and ultrasonic extraction), extract purification and self-determination by gas chromatography with electron capture detector (GC / ECD). In the samples of sediment were detected these PCB congeners (138, 153 and 180) and organochlorine pesticides (b-HCH, HCB, p,p’-DDE, p,p’-DDD, p,p’-DDT and o,p’-DDT).. In soil samples were detected PCB congener 28 and organochlorine pesticides (HCB, b-HCH, heptachlor, aldrin, dieldrin, p,p’-DDE, p,p’-DDD, p,p’-DDT and o,p’-DDT).

This thesis contains information about fast measuring card design for data processing from NQR measuring probe. The overall purpose is to create functional prototype of measuring card. Thesis describes suitable design of PCB having regard to EMC. There are information abou digital signal processing, using algorithms DFT and FFT. The thesis contains information about FPGA and there are rules, how to program FPGA correctly. In the practical part of the thesis, there are information about PCB design of ADC and DAC. There are also information about design of program for FPGA and control application for PC.

This diploma thesis is a part of a project of two students. The aim of the project is to design safer electronics for the unstable balancing vehicle HUMMER and implementation of advanced diagnostics and fault detection. In the first part of the project we analysed the original vehicle using the FMEA analyse and created a new concept of the vehicle. The second part of the project describes a new hardware. I designed and tested the power electronics, control unit and supplies. The outputs of the work are prototypes which allow testing a new concept.

The Diploma thesis is focused on reballing of BGA packages with the device PACE TF 2700. It describes the general types of BGA packages, their defects, importance of thermal management to the solder techniques, where it is also talked about the meaning of solders and fluxes for the joint. The work informs about the most common methods of reballing, the proper handling of components and the current situation with BGA stencils on the market. It briefly describes the device operation of PACE TF 2700, that is working on the convection and IR principle of heating components. It deals with the manufacturing of the template, dummy BGA packages, the test plates, creation of the thermo profile, comparing and examining the defects and their causes, which had the most significant impact on the results. The achievements would serve for comparing them with the results of the future laboratory exercises or as a subject for further works.

This master thesis deals with the design and realization of a drive for a 500 W BLDC motor powered with a battery power supply. It also deals with the possibilities of realization of drives and other possibilities to control these motors. Describes the implementation of the inverter using Atmel's AVR microcontroller. The thesis also deals with the design of an auxiliary switching inverter. Communication with UART and CAN interface is also implemented.

The ability of Chromolaena odorata propagated by stem cuttings and grown for six weeks in the greenhouse to thrive in soil containing different concentrations of PCB congeners found in Aroclor and transformer oil, and to possibly remediate such soil was studied under greenhouse conditions. Chromolaena odorata plants were transplanted into soil containing 100, 200, and 500 ppm of Aroclor and transformer oil (T/O) in 1L pots. The experiments were watered daily at 70% moisture field capacity. Parameters such as mature leaves per plant, shoot length, leaf colour as well as the root length at harvest were measured. C. odorata growth was negatively affected by T/O in terms of shoot length and leaf numbers, but no growth inhibition was shown by Aroclor. At the end of six weeks of growth, Plants size was increased by 1.4 and 0.46%, but decreased at -1.0% in T/O, while increases of 45.9, 39.4 and 40.0% were observed in Aroclor treatments. Mean total PCB recoveries were 6.40, 11.7, and 55.8μg in plants tissues at Aroclor treated samples resulting in a percentage reduction of PCB from the soil to 2.10, 1.50, and 1.10 at 100, 200, and 500mg/kg Aroclor treatments respectively. There was no PCB recovery from plants in transformer oil treatments as a result of its inhibition to growth. Root uptake was found to be the probable means of remediation of PCB-contaminated soil by C. odorata, this was perhaps aided by microbes. This study has provided evidence on the ability of C. odorata to remediate PCB contaminated soil. However, the use of C. odorata for phytoremediation of PCB contaminated soil under field condition is therefore advised. / Environmental Sciences / M.Sc. (Environmental Science)

The most essential unit required for all the electronic devices is the Power Supply Unit (PSU). The main objective of power supply designers is to reduce the size, cost and weight, and to increase the power density of the converter. There is also a requirement to have a lower loss in the circuit and hence in the improvement of energy efficiency of the converter circuit. Operating the converter circuits at higher switching frequencies reduces the size of the passive components such as transformers, inductors, and capacitors, which results in a compact size, weight, and increased power density of the converter. At present the switching frequency of the converter circuit is limited due to the increased switching losses in the existing semiconductor devices and in the magnetic area, because of increased hysteresis and eddy current loss in the core based transformer. Based on continuous efforts to improve the new semi conductor materials such as GaN/SiC and with recently developed high frequency multi-layered coreless PCB step down power transformers, it is now feasible to design ultra-low profile, high power density isolated DC/DC and AC/DC power converters. This thesis is focussed on the design, analysis and evaluation of the converters operating in the MHz frequency region with the latest semi conductor devices and multi-layered coreless PCB step-down power and signal transformers. An isolated flyback DC-DC converter operated in the MHz frequency with multi-layered coreless PCB step down 2:1 power transformer has been designed and evaluated. Soft switching techniques have been incorporated in order to reduce the switching loss of the circuit. The flyback converter has been successfully tested up to a power level of 10W, in the switching frequency range of 2.7-4 MHz. The energy efficiency of the quasi resonant flyback converter was found to be in the range of 72-84% under zero voltage switching conditions (ZVS). The output voltage of the converter was regulated by implementing the constant off-time frequency modulation technique. Because of the theoretical limitations of the Si material MOSFETs, new materials such as GaN and SiC are being introduced into the market and these are showing promising results in the converter circuits as described in this thesis. Comparative parameters of the semi conductor materials such as the vi energy band gap, field strengths and figure of merit have been discussed. In this case, the comparison of an existing Si MOSFET with that of a GaN MOSFET has been evaluated using a multi-layered coreless PCB step-down power transformer for the given input/output specifications of the flyback converter circuit. It has been determined that the energy efficiency of the 45 to 15V regulated converter using GaN was improved by 8-10% compared to the converter using the Si MOSFET due to the gate drive power consumption, lower conduction losses and improved rise/fall times of the switch. For some of the AC/DC and DC/DC applications such as laptop adapters, set-top-box, and telecom applications, high voltage power MOSFETs used in converter circuits possess higher gate charges as compared to that of the low voltage rating MOSFETs. In addition, by operating them at higher switching frequencies, the gate drive power consumption, which is a function of frequency, increases. The switching speeds are also reduced due to the increased capacitance. In order to minimize this gate drive power consumption and to increase the frequency of the converter, a cascode flyback converter was built up using a multi-layered coreless PCB transformer and this was then evaluated. Both simulation and experimental results have shown that with the assistance of the cascode flyback converter the switching speeds of the converter were increased including the significant improvement in the energy efficiency compared to that of the single switch flyback converter. In order to further maximize the utilization of the transformer, to reduce the voltage stress on MOSFETs and to obtain the maximum power density from the power converter, double ended topologies were chosen. For this purpose, a gate drive circuitry utilising the multi-layered coreless PCB gate drive transformer was designed and evaluated in both a Half-bridge and a Series resonant converter. It was found that the gate drive power consumption using this transformer was less than 0.8W for the frequency range of 1.5-3.5MHz. In addition, by using this gate drive circuitry, the maximum energy efficiency of the series resonant converter was found to be 86.5% with an output power of 36.5W.

The Power Supply Unit (PSU) plays a vital role in almost all electronic equipment. The continuous efforts applied to the improvement of semiconductor devices such as MOSFETS, diodes, controllers and MOSFET drivers have led to the increased switching speeds of power supplies. By increasing the switching frequency of the converter, the size of passive elements such as inductors, transformers and capacitors can be reduced. Hence, the high frequency transformer has become the backbone in isolated AC/DC and DC/DC converters. The main features of transformers are to provide isolation for safety purpose, multiple outputs such as in telecom applications, to build step down/step up converters and so on. The core based transformers, when operated at higher frequencies, do have limitations such as core losses which are proportional to the operating frequency. Even though the core materials are available in a few MHz frequency regions, because of the copper losses in the windings of the transformers those which are commercially available were limited from a few hundred kHz to 1MHz. The skin and proximity effects because of induced eddy currents act as major drawbacks while operating these transformers at higher frequencies. Therefore, it is necessary to mitigate these core losses, skin and proximity effects while operating the transformers at very high frequencies. This can be achieved by eliminating the magnetic cores of transformers and by introducing a proper winding structure. A new multi-layered coreless printed circuit board (PCB) step down transformer for power transfer applications has been designed and this maintains the advantages offered by existing core based transformers such as, high voltage gain, high coupling coefficient, sufficient input impedance and high energy efficiency with the assistance of a resonant technique. In addition, different winding structures have been studied and analysed for higher step down ratios in order to reduce copper losses in the windings and to achieve a higher coupling coefficient. The advantage of increasing the layer for the given power transfer application in terms of the coupling coefficient, resistance and energy efficiency has been reported. The maximum energy efficiency of the designed three layered transformers was found to be within the range of 90%-97% for power transfer applications operated in a few MHz frequency regions. The designed multi-layered coreless PCB transformers for given power applications of 8, 15 and 30W show that the volume reduction of approximately 40-90% is possible when compared to its existing core based counterparts. The estimation of EMI emissions from the designed transformers proves that the amount of radiated EMI from a three layered transformer is less than that of the two layered transformer because of the decreased radius for the same amount of inductance. Multi-layered coreless PCB gate drive transformers were designed for signal transfer applications and have successfully driven the double ended topologies such as the half bridge, the two switch flyback converter and resonant converters with low gate drive power consumption of about half a watt. The performance characteristics of these transformers have also been evaluated using the high frequency magnetic material made up of NiZn and operated in the 2-4MHz frequency region. These multi-layered coreless PCB power and signal transformers together with the latest semiconductor switching devices such as SiC and GaN MOSFETs and the SiC schottky diode are an excellent choice for the next generation compact SMPS.

Electric vehicles are increasing on the market and new technologies are being investigated because of the demand placed on electrified drivelines to provide maximum efficiency. Electric motors are expected to provide high efficiency and thus precise and compact designs of sensors for electric motors are requested. Market sensors offers a broad variety of sensors which are useful and optimal for different applications. Inductive sensors are investigated by industries because of their characteristics of having high accuracy, robustness, compact and flexible design and tolerant to harsh environments. This thesis is an investigation of inductive position sensors for automotive rotor applications,requested by one of Sweden’s largest companies within the automotive industry. The goal of the project is to design and implement theory of tradtional resolver technology on a printed circuit board (PCB) and conduct concept verifications of the system. Furthermore a new concept in the design is introduced and applied to the angular position sensor, working as a vernier scale and improve the resolution. Results and outcomes of this thesis are meant to facilitate future work and breakthroughs regarding inductive position sensors. This thesis aim to conduct a deep dive in electronics and signal processing and to derive the fundamentals of electromagnetism, from Maxwell’s equations to modern sensor design and to bring a new discussion to the table regarding the traditional measuring target used for rotor position in automotive industries. A new design working as rotor target design is presented and verified in this thesis and the results and outcomes are meant to facilitate future work and breakthroughs regarding inductive position sensors and potentially increase the accuracy and thus the efficiency of electric vehicles.

Byla provedena studie bioakumulace POP v potravním řetězci a historických trendů hladin POP v sedimentech Brněnské přehrady. Současné úrovně kontaminantů byly stanoveny v jelci tloušti z řeky Svratky a rovněž byla posouzena hygienická kvalita ryb z rekreačního rybolovu. Současné úrovně POP v terestrickém ekosystému byly posouzeny pomocí analýz jehličí jako přirozeného indikátoru znečištění. Studium jedinců tří druhů dravých ptáků z ČR bylo zaměřeno na zhodnocení kontaminace těchto vrcholných predátorů POP. S pomocí analýz vybraných druhů ryb ze Záhlinických rybníků byl rovněž studován proces bioakumulace. Posouzení parametrů dvou moderních extrakčních technik a jejich využitelnosti pro izolaci POP z různých matric bylo námětem poslední části dizertace.