The theses is focused on the use of PLC technology. The aim of the thesis is creating device which communicates in a narrowband transmission frequency band. Transmission of communication between plc elements runs through the low voltage distribution network. The frequency and phase modulations are used in order to change the character of data signal. Transmitter and receiver parameters are subjects to the CENELEC standard. The theses gives more attention to the area of hardware build communication element rather than the area of programming.

The theses is focused on the use of PLC technology. The aim of the thesis is creating device which communicates in a narrowband transmission frequency band. Transmission of communication between plc elements runs through the low voltage distribution network. The frequency and phase modulations are used in order to change the character of data signal. Transmitter and receiver parameters are subjects to the CENELEC standard. The theses gives more attention to the area of hardware build communication element rather than the area of programming.

This dissertation is particularly focused on a novel approach of a wirelessly powered neuromodulation system for chronic patients. The inductively coupled transmitter (TX) and receiver (RX) coils are designed through optimization to achieve maximum efficiency. A power management unit (PMU) consisting of a voltage rectifier, voltage regulator along with a stimulation circuitry is also designed to provide pulse stimulation to genetically modified neurons. For continuous health monitoring purposes, the response from the brain due to stimulation needs to be recorded and transmitted wirelessly outside the brain for analysis. A low-power high-data duty-cycled impulse-radio ultra-wideband (IR-UWB) transmitter is designed and implemented using the standard CMOS process. Another focus of this dissertation is the design of a reverse electrowetting-on-dielectric (REWOD) based energy harvesting circuit for wearable sensor applications which is capable of generating a very low-frequency signal from motion activity such a walking, running, jogging, etc. A commercial off-the-shelf (COTS) based and on-chip based energy harvesting circuit is designed for very low-frequency signals. The experimental results show promising progress towards the advancement in the wirelessly powered neuromodulation system and building the self-powered wearable sensor.

Small cantilevers with ultra-high resonant frequencies (1–3 MHz) have paved the way for high-speed atomic force microscopy. However, their potential for multi-frequency atomic force microscopy is unexplored. Because small cantilevers have small spring constants but large resonant frequencies, they are well-suited for the characterisation of delicate specimens with high imaging rates. We demonstrate their imaging capabilities in a bimodal frequency modulation mode in constant excitation on semi-crystalline polypropylene. The first two flexural modes of the cantilever were simultaneously excited. The detected frequency shift of the first eigenmode was held constant for topographical feedback, whereas the second eigenmode frequency shift was used to map the local properties of the specimen. High-resolution images were acquired depicting crystalline lamellae of approximately 12 nm in width. Additionally, dynamic force curves revealed that the contrast originated from different interaction forces between the tip and the distinct polymer regions. The technique uses gentle forces during scanning and quantified the elastic moduli Eam = 300 MPa and Ecr = 600 MPa on amorphous and crystalline regions, respectively. Thus, multimode measurements with small cantilevers allow one to map material properties on the nanoscale at high resolutions and increase the force sensitivity compared with standard cantilevers. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

An investigation into performance improvements to the modulator stage of a class-D amplifier is conducted in this thesis. Two of the standard topologies, namely class-D open-loop pulse-width modulation (PWM), and the improved self-oscillating feedback system are benchmarked against a topology which includes both a hysteretic comparator in a feedback loop and triangle wave injection. Circuit performance is analyzed by comparing how the triangle injection circuit handles known issues with open-loop and self-oscillating circuits. Using this analysis, it is shown that the triangle injection topology offers an improved power supply rejection ratio relative to open-loop PWM and reduces distortion generated by frequency modulation characteristic of the self-oscillating topology.

The purpose of the current exploration is creation of the mathematical model of different modifications of the underlying surface of the «forest» type. During the exploration the mathematical model of the beating signal of the altimeter was created. That’s allows to explore facet models of different types of underlying surfaces. The model was designed in the MATLAB system. As the result of the exploration the mathematical models of the underlying surfaces for different types of forests were created. During the modeling process it was designed two different variants of the model. The first variant corresponded only to the MATLAB system and based on the layers during the modeling process. The second variant is based on the 3D-Max model of the underlying surface with the following processing into the MATLAB system. The explored variants of the model allows to stress facet parameters during the furtherer exploration of the different types of the underlying surfaces. The diploma project contains four parts and includes 144 pages, 72 figures, 31 sources, 6 appendixes, 58 formulas. / Целью данной работы является создание математической модели различных модификаций подстилающей поверхности типа лес. В процессе работы была создана математическая модель сигнала биений радиовысотомера, позволяющая исследовать фацетные модели различных типов подстилающей поверхности. Модель разработана в математическом пакете MATLAB. В результате исследований созданы математические модели подстилающей поверхности для различных видов лесов. При моделировании поверхности было разработано два подхода. Первый подход использует только программный пакет MATLAB и основан на моделировании наборов фацетов в виде слоев. Второй подход основан на построении требуемой поверхности в программе трехмерной визуализации (3Ds MAX) с дальнейшей обработкой экспортированных данных с помощью разработанной модели в среде MATLAB. Исследованные подходы моделирования поверхности позволяют изучать различные типы подстилающих поверхностей, акцентируя внимание на разных параметрах фацетов. Дипломный проект содержит 144 страницы, 72 рисунка, 31 источник, 6 приложений, 58 формул, состоит из четырех глав.

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Isolated inverter can provide galvanic isolation which is necessary for some applications with safety regulations. Traditionally, a two-stage configuration is widely applied with isolated dc-dc stage and a sinusoidal pulse-width-modulated (SPWM) dc-ac stage. However, this two-stage configuration suffers from more components count, more complex control and tend to have lower efficiency and lower power density. Meanwhile, a large dc bus capacitor is needed to attenuate the double line frequency from SPWM for two-stage configuration. Therefore, the single-stage approach including an isolated dc-rectified sine stage and a line frequency unfolder is preferable. Since the unfolder circuit is at line frequency being almost lossless, the isolated dc-rectified sine stage becomes critical. However, the relevant research for the single-stage isolated inverter is limited. People either utilize PWM based converter as dc-rectified sine stage with duty cycle adjustment or apply SRC or LLC resonant converter for better soft switching characteristics. For PWM based converter, hard switching restricts the overall inverter efficiency, while for SRC/LLC, enough wide voltage gain range and full range ZVS are the major issues. This dissertation aims to provide solutions for a high-efficiency, high-frequency resonant converter based single-stage soft-switching isolated inverter design. The LLC and LCLCL resonant converters are applied as the isolated dc-rectified sine stage with variable frequency modulation (VFM). Therefore, the rectified sine wave generation consists of many dc-dc conversion with different switching frequencies and an efficient dc-rectified sine stage design needs each dc-dc conversion to be with high efficiency. This dissertation will first propose the optimization methods for LLC converter dc-dc conversion. ZVS models are derived to ensure fully ZVS performance for primary side GaN devices. As a large part in loss breakdown, the optimization for transformer is essential. The LLC converter can achieve above 99% efficiency with proposed optimization approach. Moreover, the channel turn-off energy model is presented for a more accurate loss analysis. With all the design and optimization considerations, a MHz LLC converter based isolated inverter is designed and a hybrid modulation method is proposed, which includes full bridge (FB) VFM for output high line region and half bridge (HB) VFM for output low line region. By changing from FB to HB, the output voltage gain is reduced to half to have a wider voltage gain range. However, the total harmonic distortion (THD) of output voltage at light load will be impacted since the voltage gain will be higher with lighter load at the maximum switching frequency. A MHz LCLCL converter based isolated inverter is proposed for a better output voltage THD at light load conditions. The paralleled LC inside the LCLCL resonant tank can naturally create a zero voltage gain point at their resonant frequency, which shows superior performance for rectified sine wave generation. Besides the better THD performance, the LCLCL converter based isolated inverter also features for easier control, better ZVS performance and narrower switching frequency range. Meanwhile, the LCLCL based inverter topology has bi-directional power flow capability as well. With variable frequency modulation for ac-dc, this topology is still a single-stage solution compared to the traditional two-stage solution including PFC + LLC configuration. / Doctor of Philosophy / Inverters can convert dc voltage to ac voltage and typically people use two-stage approach with isolated dc-dc stage and dc-ac stage. However, this two-stage configuration suffers from more components count, more complex control and tend to have lower efficiency and lower power density. Therefore, the single-stage solution with dc-rectified sine wave stage and a line frequency unfolder becomes appealing. The unfolder circuit is to unfold the rectifier sine wave to an ac sine wave at the output. Since the unfolder is at line frequency and can be considered lossless, the key design is for the dc-rectified sine stage. The resonant converter featured for soft switching seems to be a good candidate. However, the inverter needs soft switching for the whole range and an enough wide voltage gain, which makes the design difficult, especially the target is high efficiency for the overall inverter. This dissertation aims to provide solutions for a high-efficiency, high-frequency resonant converter based single-stage soft-switching isolated inverter design. The LLC and LCLCL resonant converters are applied as the isolated dc-rectified sine stage with variable frequency modulation (VFM). Therefore, the rectified sine wave generation consists of many dc-dc conversion with different switching frequencies and an efficient dc-rectified sine stage design needs each dc-dc conversion to be with high efficiency. The design considerations and optimization methods for the LLC dc-dc conversion are firstly investigated. Based on these approaches, a MHz LLC converter based isolated inverter is designed with proposed hybrid modulation method. To further improve the light load performance, a MHz LCLCL converter based isolated inverter topology is proposed. The paralleled LC inside the LCLCL resonant tank can naturally create a zero voltage gain point which shows superior characteristics for rectified sine wave generation. Moreover, the LCLCL resonant converter based topology has bi-directional capability as well so it can work well for ac voltage to dc voltage conversion.

With the increasing demands on electronic loads (e.g. desktop, laptop, monitor, LED lighting and server) in modern technology-driven lives, performance of switched-mode power supply (SMPS) for electronics have been growing to prominence. As front-end converters in typical SMPS structure, ac-dc power-factor correction (PFC) circuits play a key role in regulations of input power factor, harmonics and dc output voltage, which has a decisive effect on entire power-supply performances. Universal ac-line and low-power system (90–264 Vrms, up to 300–400 W) is one of the most common power-supply specifications and boost-derived PFC topologies have been widely used for the purpose. In order to concurrently achieve high efficiency and low-cost system in the PFC stage, zero-current switching (ZCS) control schemes are highly employed in control principles. Representative schemes are discontinuous conduction mode (DCM) and critical conduction mode (CRM). Both modes can realize ZCS turn-on without diode reverse recovery so that low switching losses and low-cost diode utilizations are obtainable. Among various boost-family PFC topologies, three-level boost (TLB) converter has generated considerable research interest in high-voltage high-power applications. It is mainly due to the fact that the topology can have halved component voltage stresses, improved waveform qualities and electromagnetic interference (EMI) from phase interleaved continuous conduction mode (CCM) operations, compared to other two-level boost PFC converters. On the other hand, in the field of universal-line low-power applications, TLB PFC has been thoroughly out of focus since doubled component counts and increased control complexity than two-level topologies are practical burden for the low-cost systems. However, recent researches on TLB PFC with ZCS control schemes have found that cost-competitiveness of the topology is actually comparable to two-level boost PFC converters because the halved component voltage stresses enable usage of low voltage-rating components of which unit prices are cheaper than higher-rating ones. Based on the justification, researches on ZCS control schemes for TLB PFC have been conducted to get enhanced waveform qualities and performance factors. Following the research stream, a three-level current modulation scheme that can be adopted in both DCM and CRM is proposed in Chapter 2 of this dissertation. Main concept of the proposed current modulation is additional degree-of-freedom in current-slope shaping by differentiating on-times of two active switches, which cannot be found from any other single-phase boost-derived PFC topologies. Using the multilevel feature, proposed operations in one switching period consist of three steps: common-switch on-time, single-switch on-time and common-switch off-time. The single-switch on-time step is key design factor of the proposed modulation that can be utilized either in fixed or adjustable form depending on control purpose. Based on the basic modulation concept, three-level CRM control scheme, adjustable three-level DCM control scheme, and spread-spectrum frequency modulation (SSFM) with adjustable three-level DCM scheme are proposed in Chapter 3–5, respectively. In each chapter, implemented control scheme aims to improve different performance factors. In Chapter 3, the proposed three-level CRM scheme uses increased single-switch on-time period to reduce peak inductor current and magnitude of variable switching frequency. It is generally accepted fact that CRM operations suffer from high switching losses and poor efficiency at light load due to considerable increment of switching frequency. Thus, efficiency improvement effect by the proposed CRM scheme becomes remarkable as load condition goes lighter. In experimental verifications, maximum improvement is measured by 1.2% at light load (20%) and overall efficiency is increased by at least 0.4% all over the load range. In Chapter 4, three-level DCM control scheme adopts adjustable single-switch on-time period in fixed switching-frequency framework. The purpose of adjustable control scheme is to widen the length of non-zero inductor current period as much as possible so that discontinued current period and high peak current of DCM operations can be minimized. Experiment results show that, compared to conventional two-level DCM control, full-load peak inductor currents are reduced by 20.2% and 17.1% at 110 and 220 Vrms input voltage conditions, respectively. Moreover, due to turn-off switching energy decrements by the turn-off current reductions, efficiency is also improved by at least 0.4% regardless of input voltage and load conditions. In Chapter 5, a downward SSFM technique is developed first for DCM operations of boosting PFC converters including two-level topologies. This chapter aims to achieve significant reduction of high differential-mode (DM) EMI amplitudes from DCM operations, which is major drawback of DCM control. By using the simple linearized frequency modulation, peak DM EMI noise at full load condition is reduced by 12.7 dBμV than conventional fixed-frequency DCM control. On top of the proposed SSFM, the adjustable three-level DCM control scheme in Chapter 4 is adopted to get further reductions of EMI noises. Experimental results prove that the collaborations of SSFM and adjustable DCM scheme reduce the EMI amplitudes further by 2.5 dBμV than the result of SSFM itself. The reduced EMI amplitudes are helpful to design input EMI filter with higher cut-off frequency and smaller size. Different from two-level boosting PFC converters, TLB PFC topology has two output capacitors in series and inherently suffers from voltage unbalancing issue, which can be noted as topological trade-off. In Chapter 6, two simple but effective voltage balancing schemes are introduced. The balancing schemes can be easily built into the proposed ZCS control schemes in Chapter 3–5 and experimental results validate the effectiveness of the proposed balancing principles. For all the proposed control schemes in this dissertation, detailed operation principles, derivation process of key equations, comparative analyses, implementation method with digital controller and experimental verifications with TLB PFC prototype are provided. / Doctor of Philosophy / Electronic-based devices and loads have been essential parts of modern society founded on rapid advancements of information technologies. Along with the progress, power supplying and charging of electronic products become routinized in daily lives, but still remain critical requisites for reliable operations. In many power-electronics-based supplying systems, ac-dc power-factor correction (PFC) circuits are generally located at front-end to feed back-end loads from universal ac-line sources. Since PFC stages have a key role in regulating ac-side current quality and dc-side voltage control, the importance of PFC performances cannot be emphasized enough from entire system point of view. Thus, advanced control schemes for PFC converters have been developed in quantity to achieve efficient operations and competent power qualities such as high power factor, low harmonic distortions and low electromagnetic interferences (EMI) noises. In this dissertation, a sort of PFC topologies named three-level boost (TLB) converter is chosen for target topology. Based on inherent three-level waveform capability of the topology, multiple zero-current switching (ZCS) control schemes are proposed. Compared to many conventional two-level PFC topologies, TLB PFC can provide additional degree-of-freedom to current modulation. The increased control flexibility can realize improvements of various waveform qualities including peak current stress, switching frequency range, harmonics and EMI amplitude. From the experimental results in this dissertation, improvements of waveform qualities in TLB PFC with the proposed schemes are verified with comparison to two-level current control schemes; in terms of efficiency, the results show that TLB PFC with the proposed schemes can have similar converter efficiency with conventional two-level boost converter in spite of increased component counts in the topology. Further, the proposed three-level control schemes can be utilized in adjustable forms to accomplish different control objectives depending on system characteristics and applications. In each chapter of this dissertation, a novel control scheme is proposed and explained with details of operation principle, key equations and digital implementation method. All the effectiveness of proposals and analyses are validated by a proper set of experimental results with a TLB PFC prototype.

Die Modulation von Distorsionsprodukt-Otoemissionen (DPOAE) durch Töne tiefer Frequenz ist ein Methode, mit der die Auswirkung von Verlagerungen der kochleären Trennwand auf die Funktion des kochleären Verstärkers untersucht werden kann. Damit bietet sie einen neuen objektiven Ansatz zur Diagnostik unterschiedlicher kochleärer Hörstörungen sowie zur Untersuchung physiologischer Mechanismen der Kochlea. Durch einen tieffrequenten Ton (f = 32,8 Hz) werden die DPOAE in Abhängigkeit von dessen Phase periodisch verändert. Die Ausprägung der Modulation hängt von den Parametern des Tieftons und der Primärtöne (mit den Frequenzen f1 und f2) ab. Bei zwölf normalhörenden Probanden wird der Einfluß des Tieftonpegels, der Primärtonpegel und der Primärtonfrequenzen auf die Modulation der DPOAE mit der Frequenz 2f1-f2 untersucht. Die Ergebnisse dieser Methode werden mit denen der subjektiven Phasenaudiometrie bei diesen Probanden verglichen. Mit den Primärtonfrequenzen f1 = 2,5 und f2 = 3 kHz steigt die mittlere Modulationstiefe der DPOAE mit zunehmendem Tieftonpegel sowie mit abnehmenden Primärtonpegeln nichtlinear. Mit hohem Tieftonpegel (L = 115 dB SPL) und geringen Primärtonpegeln (bis zu L1 = 50 und L2 = 30 dB HL) sind DPOAE-Pegelverläufe mit zwei Minima und zwei Maxima pro Tieftonperiode zu beobachten. Die Pegelminima liegen kurz nach der maximalen Druck- bzw. Sogphase des Tieftons vor dem Trommelfell, entsprechend der maximalen Auslenkung der kochleären Trennwand in Richtung Scala vestibuli bzw. Scala tympani. Sie zeigen eine mittlere Latenz von 4 ms gegenüber den Verdeckungsmaxima der subjektiven Mithörschwelle im Phasenaudiogramm, die wahrscheinlich durch die Summe der Antwortzeit der aktiven kochleären Prozesse und der Laufzeit der DPOAE-Signale retrograd aus der Kochlea zur Meßsonde im äußeren Gehörgang zustande kommt. Mit geringeren Tieftonpegeln (L = 110 dB SPL) bzw. höheren Primärtonpegeln (ab L1 = 55 und L2 = 40 dB HL) sowie höheren Primärtonfrequenzen (f1 = 4, f2 = 4,8 kHz) sind nur noch jeweils ein DPOAE-Pegelminimum und -maximum pro Tieftonperiode zu beobachten. Mit den Primärtonfrequenzen f1 = 5 und f2 = 6 kHz zeigt sich keine Modulation der DPOAE mehr. Die Ergebnisse werden unter Verwendung einer Boltzmannfunktion zweiter Ordnung als Annäherung an die mechano-elektrische Transferfunktion äußerer Haarzellen simuliert. Bei einigen Probanden werden außerdem die Modulation der DPOAE mit der Frequenz 3f1-2f2 durch den tieffrequenten Ton sowie der Einfluß spontaner otoakustischer Emissionen (SOAE) auf die Messung tieftonmodulierter DPOAE untersucht. / Low-frequency modulation of distortion product otoacoustic emissions (DPOAE) is a method which allows to investigate the effect of the displacement of the cochlear partition on the function of the active cochlear process. It offers a new objective approach to diagnose different sensory hearing disorders as well as to investigate physiological cochlear mechanisms. The DPOAE are modulated by a low-frequency tone (with the frequency f = 32,8 Hz), depending on its phase. The extent of this modulation depends on the acoustic parameters of the suppressing low-frequency tone and the stimulating primary tones (f1 and f2). In twelve normal hearing subjects the influence of the low-frequency tone level, the levels and the frequencies of the primary tones on the modulation of the DPOAE with the frequency 2f1-f2 are investigated. In these subjects, the phase-dependent masked subjective threshold is also registered. The results of both methods are compared. With the primary tone frequencies f1 = 2,5 and f2 = 3 kHz the mean value of the DPOAE modulation depth presents a nonlinear growth with increasing low-frequency tone level and decreasing primary tone levels, respectively. With high low-frequency tone level (L = 115 dB SPL) and low primary tone levels (up to L1 = 55 and L2 = 40 dB HL), the time course of the DPOAE level shows two minima and two maxima within one period of the low-frequency tone. The minimal DPOAE levels are registered shortly after the phases of maximal condensation and rarefaction of the low-frequency tone in front of the eardrum, respectively, corresponding to the largest displacement of the cochlear partition towards the scala tympani and the scala vestibuli. The time course of the DPOAE level shows a mean latency of 4 ms with regard to the masking patterns of the phase-dependent masked threshold, due to the response time of the active cochlear process and the retrograde travelling time of the DPOAE. With lower low-frequency tone levels (L1 = 110 dB SPL), higher primary tone levels (from L1 = 55, L2 = 40 dB HL), and higher primary tone frequencies (f1 = 4, f2 = 4,8 kHz), respectively, the DPOAE level presents only one maximum and one minimum per period of the low-frequency tone. With the primary frequencies f1 = 5 and f2 = 6 kHz no modulation of the DPOAE is registered. The results are simulated using a second-order Boltzmann function as an approximation of the mechano-electric transfer function of the outer hair cells. Additionally, in some subjects the low-frequency modulation of the DPOAE with the frequency 3f1-2f2 and the influence of spontaneous otoacoustic emissions (SOAE) on the registration of low-frequency modulated DPOAE are investigated.