Interference of Spread-Spectrum Modulated Disturbances on Digital Communication Channels

In this paper, the effects of random spread spectrum (SS) electromagnetic interference (EMI) on digital communications are addressed. For this purpose, the influence of EMI on a communication channel is described in the framework of information theory in terms of an equivalent channel capacity loss, which is analytically predicted and validated by experimental results. The EMI-induced channel capacity loss for non-modulated and SS-modulated interference generated by a switching-mode DC-DC power converter are then evaluated for different EMI and channel characteristics so that to compare different scenarios of practical interest

Development of novel low noise switch-mode power supply designs for high fidelity audio power amplifiers.

Today, linear power supplies are widely used to provide the supply voltage rail to an audio amplifier and are considered bulky, inefficient and expensive due to the presence of various components. In particular, the typical requirements of linear designs call for physically large mains transformers, energy storage/filtering inductors and capacitors. This imposes a practical limit to the reduction of weight in audio power systems. In order to overcome these problems, Switch-mode Power Supplies (SMPS) incorporate high speed switching transistors that allow for much smaller power conversion and energy storage components to be employed. In addition the low power dissipation of the transistors in the saturated and off states results in higher efficiency, improved voltage regulation and excellent power factor ratings. The primary aim of this research was to develop and characterize a novel low noise switch mode power supply for an audio power amplifier. In this thesis, I proposed a novel balancing technique to optimize the design of SMPS that elevate the performance of converter and help to enhance the efficiency of power supply through high speed switching transistors. In fact, the proposed scheme mitigates the noise considerably in various converter topologies through different mechanisms. To validate the proposed idea, the technique is applied to different converters e.g; PFC boost converter, flyback converter and full-bridge converter. The performance of audio amplifier is evaluated using designed SMPS to compare with existing linear power supply. On the basis of experimental results, the decision has been made that the proposed balanced SMPS solution is as good as linear solution. Due to novelty and universality of balancing technique, it can provide a new path for researchers in this field to utilize the SMPS in all other audio devices by further enhancing its efficiency and reducing system noise

Design of High Power Converter with SiC MOSFETs

Tato diplomová práce se zabývá návrhem výkonového měniče založeného na topologii typu synchronní buck. Měnič je zkonstruován s využitím MOSFET tranzistorů na bázi silikon karbidu. Tato práce se věnuje analýze měniče s cílem navrhnout a realizovat řídící jednotku umožňující jak zpětnovazební regulaci měniče, tak řízení v otevřené smyčce. Za tímto účelem je odvozen analytický model měniče coby dynamického systému, který je použit pro návrh a simulaci řízení. Kontrolní jednotka je implementována s využitím 32 bitového mikrořadiče založeného na architektuře ARM. V této práci je poskytnut popis a použití klíčových periférií mikrořadiče pro realizaci řízení. Na závěr jsou shrnuty výsledky měření dynamického chování výkonových tranzistorů při provozu měniče. Pozornost je především věnována měření proudu tekoucího jedním tranzistorem s využitím běžného rezistoru pro snímání proudu a kompenzaci frekvenční charakteristiky rezistoru.This master degree thesis is concerned with the design of high power converter. The converter is based on synchronous buck topology and is realized using silicon carbide MOSFET transistors. This work deals with an analysis of such type of converter to design and realize a control unit providing feedback control of the converter. Therefore, a dynamic model of the converter is derived using a conventional technique of averaged state space modeling. The derived model is used for controller design and closed-loop control simulation. The control unit is implemented using a 32-bit ARM-based microcontroller. Hence, an insight into the microcontroller key peripherals is provided as well as a brief overview of the firmware architecture. This work concludes by a brief investigation of switching waveforms of SiC MOSFETs acquired during the converter operation. Attention is called to a transistor current measurement with a low-cost current sensing resistor and its frequency characteristic compensation

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters

High-Speed Asymmetric Self-Oscillating DC-DC Converter of Single Lithium Battery Cell Voltage

Lately, there has been a dramatically increase in demand for power electronics having reduced size, weight, and cost as well as improved dynamic performance. The dimension of a power electronic circuit mainly depends on passive components (inductor, capacitor). Increasing the switching frequency does not only leads to decrease in dimensions and weight but also provides faster transient response. The proposed converter is a buck (step-down) converter, with no external controller. By the feedback system it has, it provides constant duty ratio of around 50%. The defined ranges for the converter is 3.5 MHz, 3.5V-24V input voltage and 2V-12V output voltage. The lowest values for efficiency is defined as 70%. Since in the market, all high speed converters are on silicon, it makes them expensive to manufacture. Hence, in this converter, we are using real components from the market and later on will be assembled on a PCB. It will decrease the efficiency but the prices of manufacturing is dramatically reduced. Most important is taking parasitics into account which can kill the circuit otherwise. The proposed circuit topology with suitable gate drives is a new thing, and from business point of view, it is easy and cheap. Switching point is primary side of the transformer, hands over the sending power to the output load, and secondary side of the transformer provides inductive feedback. Thanks to inductive feedback, it provides fast response and adaptive dead-time to eliminate dead-time losses. Two different kind of gate drive circuitries are integrated to converter switches: resonant gate drive and dead-time latch circuitries. They are applied to switches which are responsible for the major part of the power losses. The overlapping time with main NMOS and PMOS switch is removed, and soft switching is observed at gate drives. Hence, around 4% efficiency increase is realized overall. Cascaded MOSFETs are introduced in order to make it available for also high voltage applications. Main NMOS and PMOS transistors work complimentary, meaning that once NMOS in ON, PMOS is OFF and vice versa. When PMOS is ON, current flows from battery to load, pulls the switching point (Vx) to battery voltage. When NMOS is ON, current flows from load to ground over the NMOS and pulls down Vx to ground. After Vx point, by using a proper filtering technique, flat DC voltage is obtained at the output. Using 3.8 V input voltage with 10 load, at the output 2.2 V is achieved with 27 mV voltage ripple. Efficiency is increased to 74% with 3.5 MHz switching frequency by the help of resonant gate drive and dead-time latch circuits. All parasitics are included and deeply studied with simulations conducted in LTSpice

Industrial and Technological Applications of Power Electronics Systems

The Special Issue "Industrial and Technological Applications of Power Electronics Systems" focuses on: - new strategies of control for electric machines, including sensorless control and fault diagnosis; - existing and emerging industrial applications of GaN and SiC-based converters; - modern methods for electromagnetic compatibility. The book covers topics such as control systems, fault diagnosis, converters, inverters, and electromagnetic interference in power electronics systems. The Special Issue includes 19 scientific papers by industry experts and worldwide professors in the area of electrical engineering