M.Ing. (Engineering Management) / In January 2008, South Africa experienced a power crisis which changed how South Africa viewed its primary energy sector. South Africa largely depends on coal to generate 77% of the country’s energy needs. Eskom is the main electricity producer and the largest in Africa. Coal is the third largest exporter earner after gold and platinum and the second largest contributor to the South African export market after platinum (Falcon and Prevost, 2012). This highlights the importance of coal to the South African energy sector and economy. According to Geologist Chris Hartnady, the estimated coal production peak is in 2020, a period where most Eskom power station and mines would reach their lifespan (Davie, 2010). There are increased concerns about the quality of coal supplied to Eskom and the preference of coal producers to export coal to international markets. This could possibly compromise the supply of domestic coal. Historically, Eskom was supplied with lower grade coal and higher grade coal was exported. The increased demand for lower quality coal in the Asian markets has been an aggravating factor for the South African government to secure the security of coal supply to Eskom (Sapa, 2012). In March 2013, the South African government declared coal a strategic resource. This implies that the State has the right to regulate and restrict the export of coal to international markets. The available research conducted, by consulting economic firms such as the mineral advisory firm XMP consultants; suggest that the declaration of coal as a strategic resource will impact negatively on the South African economy in some ways and also influence investment attraction into the country (Booyens, 2013). This research seeks to analyse the consequences of declaring coal a strategic resource in South Africa. The enormities in the research subject title, “An analysis of the consequences of declaring coal a strategic resource in South Africa”, makes it extremely difficult to cover all aspects involved in a minor dissertation and to substantially quantify the results in monetary terms due to the facet of dynamic factors involved...

The development of technologies and structures providing energy for household use in South Africa have for many years been dominated by the needs of "white" households. While these needs have been comprehensively met through cheap and efficient energy supplies, the needs of those in the "homelands" and townships have effectively been ignored. Thus, for roughly two-thirds of the population in South Africa, the struggle to meet basic energy needs for cooking, water heating, space heating and lighting is time consuming and expensive. The planning of a national energy strategy for the future can no longer overlook the energy needs of underdeveloped areas. While the immense task of building institutions and techniques for providing all with adequate and affordable energy supplies will require substantial technical intervention and a large amount of capital, ignoring these problems will incur even greater political, social and environmental costs. Interest in the field of energy for underdeveloped areas has been increasing in recent years, and has led to research on various appropriate energy technologies and the highlighting of energy problems in various locations. However, there has been no overview of experience to date, nor any comparative assessment of these technologies and their potential role in an energy supply strategy. By drawing together the body of research into one publication, this thesis hopes to provide an overview, to allow different energy technologies and supply options to be assessed and compared, and to provide a starting point for debate on suitable energy strategies for underdeveloped areas.

abstract: With the push for integration, a slew of modern switching power management circuits are operating at higher switching frequencies in order to reduce passive filter sizes. But while these switching regulators provide power conversion at high efficiencies, their output is prone to ripples due to the inherent switching behavior. These switching regulators use linear-low dropout regulators (LDOs) downstream to provide clean supplies. Typically, these LDOs have good power supply rejection (PSR) at lower frequencies but this degrades at higher frequencies. Therefore, some residual ripple is still manifested on the output. Because of this, high power supply rejection (PSR) with a wide rejection frequency band is becoming a critical requirement in linear low-dropout regulators (LDOs) used in complex systems- on-chip (SOCs). Typical LDOs achieve higher PSR within their loop-bandwidth; however, their supply rejection performance degrades with reduced loop-gain outside their loop- bandwidth. The LDOs with external filtering capacitors may also have spectral peaking in their PSR response, causing excess system- level supply noise. This work presents an LDO design approach, which achieves a PSR of higher than 68 dB up to 2 MHz frequency and over a wide range of loads up to 250 mA. The wide PSR bandwidth is achieved using a current-mode feedforward ripple canceller (CFFRC) amplifier which provides up to 25 dB of PSR improvement. The feedforward path gain is inherently matched to the forward gain of the LDO, not requiring calibration. The LDO has a fast load transient response with a recovery time of 6.1μs and has a quiescent current of 5.6μA. For a full load transition, the LDO achieves settling with overshoot and undershoot voltages below 27.6 mV and 36.36 mV, respectively. The LDO is designed and fabricated in a 180 nm bipolar/CMOS/DMOS (BCD) technology. The CFFRC amplifier helps to achieve low quiescent power due to its inherent current mode nature, eliminating the need for supply ripple summing amplifiers and adaptive biasing. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

The thesis deals with the design and construction of a switching power supply with output voltage adjustable from 0 to 1200 V and rated power of 120 W, which will be used to replace the existing high voltage power supply for the irreversible electroporation (IRE) device developed at UVEE FEEC BUT. The thesis focuses on a basic description of the IRE device, a description of usable converter topologies and a selection of the best topology for the required purpose. The selection of the control circuit concept and its design are also integral parts of the thesis. The final part of the thesis contains the assembly of the power supply and the measurement verifying its function.

In this diploma thesis there is elaborated design of low-voltage power supply block using I3T25 technology. The theoretical part describes the basic structures used in the design, using CMOS and bipolar devices. Furthermore, the properties and the analysis used in the evaluation are described. In the design part there is an elaborated design of individual parts, including voltage references, current references, DAC converter, operational amplifier. In the last part, the power supply block is subjected to simulations for verification of temperature compensated output variables and analyzed circuit functionality.

This Diploma thesis deals with the design of induction heating inverter. The main subject is optimalization for blacksmiths. There is described the designing procedure for power components and also designing of control part. Then prototype of 10 kW induction heater was made.

The master thesis deals with design of a switched DC power supply with output parameters of 30 V 60 A. The power supply uses the connection of two single switch forward converters with opposite phase. The topology was chosen based on a comparison of specific schematics in the first part. The body of the thesis is covered in chapter which deals with design and analysis of power circuits of the converter. The chapter describes detailed design of pulse transformers, dimensioning of semiconductors and cooling system of the converter. For lower power losses, the system of synchronous rectifying is chosen at the output of the circuit. The regulation of the output is based on cascade structure with a superior voltage and dependent current loop. Appropriate over current protection is provided by sensing the output current and using current transformers for primary current measure.

The main goal of this work is to design an efficient and cheap car-alarm with an electricity consumption not exceeding 1mA in the stand-by mode. The first part focuses on the conception of the car-alarm. As the best option - GPS/GSM car-alarm conception is chosen. Then the design of the switching power supply, communication via RS232 with the GSM module, and GPS module, I2C communication with accelerometer and timer IC, and design of the display module are described. Furthermore, the process of how to code/decode sms into the PDU format is also discussed in this part. The second part provides some basic empirical characteristics of the switching power supply (efficiency, switching frequency etc.). Then the owchart of the main loop is explained, followed by an example of the sms which the car-alarm sends in case a car theft. Explanation of how to set up timer, acceleration threshold and the time between the check of the sms commads is the subject of the next section. Fifth part deals with the installation the car-alarm into a car which is illustrated on the Skoda Favorit example. Total costs and also different cost items are listed just before concluding and suggesting some potential improvements of the device.

This thesis examines issues connected to safe uninterruptible power supplies. The term safe uninterruptible power supply is used for an aggregate of devices providing power for appliances that participate in safe rapid shutdown of a power plant in case power from a usual source fails. The thesis is divided into two parts – theoretical and practical. Theoretical part deals with possibilities and ways of realizing an aggregation of safe uninterruptible power supply. Various devices that can appear in the section of a safe uninterruptible power supply are listed and each device is characterized. Appliances that can be provided for by the sources of safe uninterruptible power supply are mentioned as well. These appliances are listed in accordance with ČSN standard nr. 381120. The theoretical part concludes with new trends in realization of safe uninterruptible power supplies. One of these sources is a clean source technology that can also be implemented in various ways. Practical part contains a suggestion of a safe uninterruptible power supply for particular steam power plant. This suggested safe uninterruptible power supply consists of rectifiers, batteries, inverters and a dieselgenerator. Calculated parameters of each device at the conclusion of the practical part are followed by a diagram of the suggested section of safe uninterruptible power supply.

The aim of this study is a design of a control and signalling unit for sport meetings controlled by a microcontroller. The unit should display the time, the state of the match, eventually another data important for a course of the match. It should be fitted by an audible alarm of the end of the match. A touch control panel with a liquid crystal display serves as input of control data. The unit operates in a countdown mode, it is possible anytime to start or to stop the time by pressing the button. The equipment is mains-operated and backed up by an external battery. In the case of a power failure, it is switched over to the battery. A representation of the time, the state of the match and other data is done by LED displays. The unit allows a connection to PC.