14,734 research outputs found
AC - DC power supply / Mohd Fahmi Abdul Halim and Mohd Fadlie Chan Mahadie Chan
No full textNowadays, AC to DC power supply is very important in our lifestyle and used widely in many commercial sectors especially in industrial, laboratory and public consumer. We also used the AC-DC power supply everyday. Hand phone charger and notebook some of application of AC-DC power supply.
Power supply introduces the operation of power supply circuits that consists of transformer, filters, rectifiers and voltage regulator. In our project, we decrease the voltage using step-down transformer. After that, a steady dc voltage is obtained by rectifying the ac voltage using the full wave bridge rectifier. The process also known as pulsating dc. In other words, it converts the ac signal to a dc signal which is unidirectional waveform (full wave waveform). Then, we filter the dc voltage to a dc level using the simple capacitor. This resulting dc voltage usually has some ripple or ac voltage variation. Finally, the dc voltage is regulated to obtain a desired fixed dc voltage. The regulation is usually obtained from an integrated circuit (IC) voltage regulator unit, which takes a dc voltage and provides somewhat lower dc voltages which remain the same even if the input dc voltage varies or the output load connected to the dc voltage changes. In other words, a voltage regulator is used to maintain a constant output voltage.
The significant advantages of this project are almost all application of electronics devices used dc voltage. For example, Walkman, radio, torchlight etc
Modelling and control of a high step-up boost DC-DC converter
No full textDue to poor power conversion of the PV system, a DC-DC boost converter with controller is optimal to boost the converter to its desired voltage. This report presents the design, implementation, and control of the modified single ended primary inductor converter (MSC). The MSC is an improved version of the single ended primary inductor convertor (SEPIC). In this project, two feedback controllers are implemented and integrated with the MSC to regulate the output voltage in the presence of desired output voltage and load changes and the controllers that will be implemented are the sliding mode controller (SMC) and non-adaptive current mode controller (CMC). The experimental results of the converter are presented to show the performance of the controller.Bachelor of Engineering (Electrical and Electronic Engineering
Common Mode Currents in DC Power Routers
No full textThe grid reinforcement and energy redirection needs have led to the emergence of Back-To-Back Voltage Source Converter (BTB-VSC) based dc power routers. This paper investigates the low frequency Common Mode Currents (CMCs) that arise in the system if the employed BTB-VSCs have an un-isolated ac path connected in parallel to their output ports. Simulation results are presented to show a sensitivity analysis of lower order harmonics in CMC with respect to the operating active and reactive power of the dc router, dc link voltage, link resistance, modulation method and pole capacitance. Experimental results are shared to show existance of lower order CMC in 3-wire ac link operating in parallel with the dc power router and these are mitigated using zero sequence controller
Modeling, Control, and Operation of an M-DAB DC-DC Converter for Interconnection of HVDC Grids
No full textFuture high-voltage direct-current (HVDC) networks based on voltage source converters (VSCs) will have different structures (asymmetric monopolar, bipolar, or symmetric monopolar), voltage levels, control, and protection schemes. Therefore, dc-dc converters are needed to interconnect those VSC-HVDC grids and several technical issues on their control and operational systems must be adequately addressed. A dc-dc converter based on a modular-dual active bridge (M-DAB) converter is suggested to reach a desirable interconnection of the HVDC grids and regulate power flow (PF) between them. A dynamic averaged model is proposed for the M-DAB converter and its stability is analyzed using the Lyapunov function. Moreover, a new local controller based on nonlinear control theory is proposed for the M-DAB. The new M-DAB local controller is integrated with the energy management system (EMS), by updating the PF equations, to create a complete control structure. Considering the CIGRE DCS3 HVDC test system and the studied M-DAB, static, dynamic simulation, and experimental studies are conducted and the dc-dc converter and the performance of the designed controllers and the EMS are examined and validated.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Intelligent Electrical Power Grid
High step-up DC-DC converter with current-mode feedback controller
No full textThe main goal of this project will be to construct and execute a high step-up DC-DC converter system that includes a feedback control. In order to achieve the voltage stability, a current-mode based controller was designed and used to regulate the output DC voltage should there be any external factors that may affect the voltage. Examples of external factors includes varying of the desired output DC voltage and a change in the output load. The literature review will provide a brief introduction of the electronics that are involved in this project. The report will include results from practical experiments that were done in order to comply with the criteria of the feedback control. In addition to conducting the practical experiments, parts of the project was simulated beforehand so as to give the author a clearer picture of the system before the practical experiments were conducted.Bachelor of Engineerin
Restructuring the existing medium voltage distribution grids using DC systems
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.DC systems, Energy conversion & Storag
Ultra step-up dc-dc converter
No full textThe objective of this project is to design and implement an Ultra-High DC-DC Converter System. The converter is able to achieve a much higher gain compared to the conventional DC-DC Boost Converter. The various controllers implemented to regulate the converter includes the voltage-based controller, current-mode based controller and adaptive controller. Both simulation and experimental results are provided to illustrate the features of the controllers under different conditions.Bachelor of Engineerin
Cold cracking in DC-cast high strength aluminum alloy ingots: An intrinsic problem intensified by casting process parameters
No full textFor almost half a century the catastrophic failure of direct chill (DC) cast high strength aluminum alloys has been challenging the production of sound ingots. To overcome this problem, a criterion is required that can assist the researchers in predicting the critical conditions which facilitate the catastrophic failure of the ingots. This could be achieved at first glance by application of computer simulations to assess the level and distribution of residual thermal stresses. However, the simulation results are only able to show the critical locations and conditions where and when high stresses may appear in the ingots. The prediction of critical void/crack size requires simultaneous application of fracture mechanics. In this paper, we present the thermo-mechanical simulation results that indicate the critical crack size distribution in several DC-cast billets cast at various casting conditions. The simulation results were validated upon experimental DC-casting trials and revealed that the existence of voids/cracks with a considerable size is required for cold cracking to occur.Materials Science & EngineeringMechanical, Maritime and Materials Engineerin
Design and implementation of controllers for DC-DC boost converters
No full textThe purpose of this project is to design and implement the controllers for DC-DC boost converters. In this project, a traditional DC-DC boost converter and a higher gain Fifth-Order DC-DC boost converter were designed and implemented. The output feedback controller was implemented for the traditional DC-DC boost converter whereas the non-adaptive current mode controller and adaptive current controller were implemented for the Fifth-Order DC-DC boost converter to observe the performances of the controllers which were investigated under various operating conditions. Experimental results are provided to illustrate the effectiveness of these controllers for the two converters.Bachelor of Engineerin
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