This paper presents the design and development of a novel Arc Welding Power Supply utilizing a modified two-switch forward converter topology. The proposed design improves the power quality by improving power factor to near unity and reducing total harmonic distortion. State space analysis of the proposed circuit showed that the circuit followed a boost-buck input output relationship. Simulation of the circuit was first implemented in LTspice to verify the functionality of the new topology. Hardware implementation of the proposed design was built on a scaled-down prototype for a proof-of-concept of the new topology. The prototype specifications were created for a 5A, 20V output with a 20-24V, 60Hz input. This project demonstrated that the proposed new topology was successful in obtaining a near unity power factor and a total harmonic distortion of less than 2%. Additionally, the prototype followed the simulation and calculations of a boost-buck function while varying duty cycle, and the final measurements aligned well with waveforms from the simulation.

This work builds on a semester project 2. from the winter semester of this academic year. The aim of this thesis is the design of converter using semiconductor components based on SiC technology. This converter is used in the construction of quick charger for electric vehicles. The design of this converter must be based on the requirements for compliance voltage safety. It describes the design of power components used in the construction of this facility, the determination of their losses and determines the overall efficiency of the converter. There is also proposed mathematical model of high-frequency transformer and made his simulation in Matlab-Simulink.

This thesis deals with a design, construciton and testing of a switch-mode power supply (SMPS) which is working as a LiFEPO4 battery charger with output current up to 100~A and output voltage up to 14,6~V. The output voltage and current can be regulated by the operator from zero to maximum value. For this SMPS Half-bridge asymmetrical forward converter with two transformers and common output inductor topology is chosen. The control circuits are run by the IC SG3525. Cascaded regulation of output voltage and current is implemented by two discrete operational amplifiers. Undervoltage protection of the control circuits and independent overcurrent protection on the primary side is also implemented.

This diploma thesis deals with design and comparison of selected DC/DC converters, where the better of them is practically realized. The first part of the diploma thesis is focused on the general analysis of DC/DC power converters. The following part is theoretical analysis focused on the first selected topology – step-up converter. The second analysed topology is forward converter with full bridge on the primary side. The theoretical analysis also includes a description of synchronous rectifier, the differences between hard and soft switching, and the types of secondary rectifiers. Another part specializes in the detailed calculation of main components of selected converters and their subsequent power dimensioning. Both designed topologies are compared according to the required aspects. The selected better topology is supplemented by the design of control circuits and an auxiliary power supply. Practical realization of converter and commissioning follows. The diploma thesis ends with verification measurements on the realized converter and their subsequent analysis.

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This diploma thesis describes particular parts of power inverter such as gate driver, DSC, LC filter, low power supply, DC/DC converter and four-quadrant bridge and manner of its control by digital signal controller. Inverter is designated for generating of a mobile artificial electric grid (for example in a car).

A drive design for an electric bike with brushed DC disk motor is proposed in this thesis. Especially the design of a DC/DC converter with DSC control is described. The converter can operate as step-down and step-up too. Minimum dimensions and sufficient power for riding without human assistance were the main demands on the design.

The thesis deals with design and construction of low-power measurement device with power over optical fiber. This device should measure input signal in range of 50 mV to 50 V and the results of measurement sent through optical fiber into sensing module.

This work builds on a semester project 2 from the winter semester of this academic year. The aim of this thesis is the design of converter using semiconductor components based on SiC technology. This converter is used in the construction of quick charger for electric vehicles. The design of this converter must be based on the requirements for compliance voltage safety. It describes the design of power components used in the construction of this facility, the determination of their losses and determines the overall efficiency of the converter. There is also proposed mathematical model of high-frequency transformer and made his simulation in Matlab-Simulink.

Important considerations of a photovoltaic (PV) source are achieving a high voltage and drawing currents with very little ripple component from it. Furthermore, the output from such a source is variable depending on irradiation and temperature. In this research, literature review of prior methods employed to boost the output voltage of a PV source is examined and their limitations identified. This research then proposes a multi-phase tapped-coupled inductor boost DC-DC converter that can achieve high voltage boost ratios, without adversely compromising performance, to be used as an interface to a PV source. The proposed converter achieves minimal current and voltage ripple both at the input and output. The suitability of the proposed converter topology for variable input voltage and variable power operation is demonstrated in this dissertation. The proposed converter is also shown to have good performance at high power levels, making it very suitable for high power applications. Detailed analysis of the proposed converter is done. Advantages of the proposed converter are explained analytically and confirmed through simulations and experimentally. Regulation of the converter output voltage is also explained and implemented using a digital controller. The simulation and experimental results confirm that the proposed converter is suitable for high power as well as variable power, variable voltage applications where high voltage boost ratios are required. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / Unrestricted