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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

Návrh a sestavení spínaného zdroje o výkonu 2,5 kW / SMPS design and assembly with an output of 2.5 kW

Pospíšilík, Vojtěch January 2014 (has links)
This diploma thesis describe the desing and assembly of switching power supply with an output of 2,5kW. At first is described the funcional principle of SPMS. The next is the proceed design of power part of the converter composed from calculation of transformer, inductors, capacitors and sizing of semiconductors. There is proceed the calculation of power looses. The next step is to make acquaintance with the possibilities of feedback control, creating a model system for simulating and executing the selection of an appropriate regulatorystructure.The following is the calculation of regulators suitable method and simulation at program MatlabSimulink. Is procced the computing and realization of regulators and finding the PWM modulator. At over is constution of contorl logic and desin of printed circuit desing, assembly and their recovery.
232

Hybridní řídicí systém pro quadrokoptéru / Hybrid Control System for Quadrocopter

Sojka, Stanislav January 2013 (has links)
This thesis deals with the design and theoretical description of the hybrid control system for quadrocopter. First, a mathematical model is presented, sensors needed for development and their principles. This work shows the system architecture design and scheme of communication channels between the blocks. Implementation section discusses specific uses of computing nodes/sensors and their settings. In this thesis there are illustrated messages sent between computing nodes and the control loop machine. It also describes how to test the sensors, measurement results and techniques for improvement.
233

Méthodes d’évaluation du risque de décharges partielles dans le bobinage de machines électriques destinées à la traction automobile / Methods for assessing the risk of partial discharges in windings of electrical machines used in electric vehicles

Benmamas, Loucif 30 November 2017 (has links)
Une machine électrique utilisée pour un entraînement à vitesse variable est généralement alimentée par un convertisseur statique dont les composants électroniques de puissance commutent extrêmement rapidement. De ce fait, chaque enroulement statorique de la machine est soumis à des fronts raides de tension dont la répartition sur les différentes spires qui le constituent dépend notamment des capacités parasites entre spires ou entre spires et carcasse. Des zones locales de fort champ électrique apparaissent dans le bobinage conduisant souvent la création d'une activité de décharges partielles. Ce travail de thèse a pour but de fournir des informations quantifiées et précises quant aux risques encourus lorsque divers paramètres liés à l'alimentation de la machine et la topologie du bobinage varient permettant de contribuer à acquérir une expertise vis à vis des problèmes liés à l’apparition de décharges partielles au sein des bobinages, et à en déduire des règles de conception. / Electrical machine used in variable speed drives are usually fed by a converter using fast switching power electronics devices. Thus, each stator winding of the machine is subjected to steep-fronted voltage pulses whose distribution over its various turns depends on the parasitic capacitances between turns or between turns and slot walls. Therefore, local areas of high electric field appear within the coil, often resulting in partial discharges activity. This thesis aims to provide accurate and quantified information regarding partial discharge inception when various parameters related to the machine power supply and winding topology so as to help develop expertise with respect to problems related to partial discharges, as well as to deduce machine design rules in this regard.
234

Automatic Torque Control for Bicycle Driven Brushless DC (BLDC) Generator

Müller, Luke, Sjöström, Kasper January 2021 (has links)
This work was carried out on behalf of Science Safari. Science Safari wants to create a product that facilitates the understanding of how much physical work is required to create electrical energy. This is done by cranking the pedals of a bicycle. The purpose of this work is to create a control unit that keeps the torque required to crank the pedals close to constant. The torque can be kept constant by creating a variable load for the generator, in this case, a pulse modulated JFET is used. The output of the current sensor and the Hall-effect sensor are used to calculate the required resistance of the JFET to keep constant torque. All this is controlled via a Raspberry Pi 3 Model B (RPi) which also shows real-time values on a display. The functionality of the sensors and JFET has largely been completed, but the assembly of all components is lacking in this work. / Detta arbete är utfört i uppdrag av Science Safari. Science Safari vill skapa en produkt som underlättar förståelsen av hur mycket fysiskt arbete som krävs för att skapa elektrisk energi. Detta genom att användaren vevar på en cykels pedaler för hand. Syftet med detta arbete är att skapa en styrenhet som ungefär håller ett konstantvridmomentet på en cykels pedaler. Vridmomentet kan hållas konstant genom att skapa en variabel last till generatorn, med hjälp av en pulsmodulerad JFET. För att beräkna vilken resistans JFETen ska ha för att hålla konstant vridmoment används en strömsensor och en Hall-effect sensor. Allt detta styrs via en Raspberry Pi 3 ModelB som även visar värden i realtid på en display. Funktionaliteten av sensorerna och JFET har till stor del färdigställts men sammansättning av alla komponenter saknas i detta arbete.
235

Test System for Charging Communication of Use Cases based on Different Standards

Patel, Jinal Vishnubhai 25 January 2022 (has links)
To charge an all types of Electric Vehicles (EVs) is the most primary part of the electrical vehicle industry. Nowadays charging communication between vehicle and charging station becoming more and more popular. Automotive industries are trying to charge vehicles in minimal time and also the secured one. In the charging communication scenario, current is flowing through the charging station to the EV through electric line and normally communication between them takes place with the help of Controller Area Network (CAN), Wi-Fi and Powerline Communication (PLC) etc. There are two types of charging communication available in the current industry: High level and Low level communication for Alternating Current (AC) and Direct Current (DC). Low Level Communication (LLC) uses only Pulse Width Modulation (PWM) signals to transmit data, which is analog signals. On the other hand, High level Communication (HLC) provides digital and IP network based communication. These both types also support many different standards for communication. For example, ISO 15118, IEC 61851, DIN 70121 and many more. These standards have the message sequences for the flow of charging and also their implementation. The goal of this thesis is the development of low cost EVSE test system, which has the PLC technology with up to 10 Mbps data rate and two different standards for charging communication with HLC. This thesis proposes an implementation between a communication controller or SECC of Electric Vehicle Supply Equipment (EVSE) side and Signal Level Attenuation Characterization (SLAC) in PLC modem. SLAC functionality helps to overcome the problem of crosstalk while charging. In this work, there will be a test system with SECC and PWM generator, some resistors to identify proper lock mechanism between charging cable and vehicle inlet, the ISO 15118 and IEC 61851 for PWM signals. Implementation of SECC will be in JAVA language and each message executed in XML script language. Our examination shows this approach very remarkable low cost AC based test system with digital communication system, which can help to test direct or virtual EV or HiL system.
236

All-digital FPGA receiver : on Intel Stratix 10 TX

Persson, Kim January 2021 (has links)
Ordinary digital receivers use analog mixers and conventional analog-to-digital converters. Thisthesis explores the possibility to build a receiver using an Intel Stratix 10 TX FPGA to sample asignal directly at its RF frequency. By band-limiting the RF signal, the transceivers can be used asPWM based analog-to-digital converters and sample the RF signals as a bit-stream. Filters andmixers could then be implemented in the FPGA to downconvert the RF signal to a complex digitalbaseband signal. This method was proven to work in theory but had drawbacks. The samplingmethod added a lot of distortion and the bandwidth was limited. The receiver could not beimplemented on the FPGA since the only connected transceivers could not be configured to receiveanalog signals. The other type of transceiver could probably be used but would have requiredanother model of the board where these were connected.
237

Design and Implementation of Simplified Sliding-Mode Control of PWM DC-DC Converters for CCM

Al-Baidhani, Humam A. 08 June 2020 (has links)
No description available.
238

Impact of Overmodulation Methods on Inverter and Machine Losses in Voltage-Fed Induction Motor Drives

Mahlfeld, Hannes, Schuhmann, Thomas, Döbler, Ralf, Cebulski, Bernd 15 August 2023 (has links)
The modulation methods Space Vector PWM (SVPWM), Discontinuous PWM (DPWM1, DPWMMAX) and six-step mode are investigated in the overmodulation range of a voltage-fed induction motor drive. This area enables an increase of inverter output voltage so that drive performance can be enhanced. Though, pulse dropping occurs which results in increased iron losses and current waveform quality degradation. Due to differences in harmonic distortion the modulation methods cause various torque oscillations and power losses in induction motors and inverter drives. To quantify these effects in a squirrel cage induction motor drive a simulation model containing a finite element machine model and an analytic inverter model is developed, in order to find the PWM scheme offering maximum torque and minimal power losses. Additionally, the holistic investigation of machine and inverter losses allows for making statements concerning total losses of drive systems and the most suitable overmodulation scheme for the application.
239

Mitigation of Background Harmonic Amplification at PCC Using Active Filtering of STATCOM

Malki, Luai January 2017 (has links)
Shunt compensation devices have been a powerful candidate for expanding the limits of transmission facilities, allowing more active power transport and supporting voltage and overall stability of the network. An example of such devices is the Static Synchronous Compensator (STATCOM) which is based on Voltage Source Converter (VSC) which synthesizes output voltage and current for mainly reactive power compensation. STATCOMs might be accompanied with a Thyristor Switched Capacitor (TSC) or Reactor (TSR) which are controllable shunt devices for extra VARs required, along with passive filters for absorbing the switching harmonics generated by the VSC. Such STATCOM topology is referred as the Hybrid STATCOM.However, such configuration typically results in parallel resonances with the maingrid’s passive elements at different harmonic frequencies. This leads to amplification of background harmonics, if any exist, at the Point of Common Coupling (PCC) where the Hybrid STATCOM is connected. This thesis deals with the VSC control in the STATCOM to mitigate the harmonic amplification behavior by active filtering,which is based on emulating an impedance by the control. Also, the overall system passivity is essentially studied, which ensures a passive system with respect to harmonics. / Shunt-kompensationsanordningar har varit en kraftfull kandidat för att öka gränserna för överföringsanläggningar, vilket möjliggör högre aktiv effekt och understöderspännings-stabilitet och övergripande stabilitet i kraftnätet. Ett exempel på sådana enheter är Static Synchronous Compensator (STATCOM) som är baserat på Voltage Source Converter (VSC) som syntetiserar utspänning och ström för huvudsakligen reaktiv effektkompensation. STATCOMs kan åtföljas av en Thyristor Switched kapacitor (TSC) eller Reaktor (TSR) som är kontrollerbara shunt-apparater som ökar kapaciteten för reaktiv effekt (VARs), tillsammans med passiva filter för att absorbera övertoner som genereras av VSC. Sådan STATCOM-topologi kallas HybridSTATCOM. Emellertid, en sådan konfiguration resulterar i parallella resonanser med huvudnätets passiva element vid olika övertoner. Detta leder till förstärkning av bakgrundsövertoner, om någon existerar, vid Point of Common Coupling (PCC) där Hybrid STATCOM är ansluten. Denna avhandling behandlar hur VSC kontrolleras i STATCOM för att mildra förstärkningen av nivåer för övertoner genom aktivfiltrering, vilket är baserat på att VSC kontrollen emulerar en impedans. Dessutom studeras övergripande systempassivitet, vilket säkerställer ett passivt system med avseende på övertoner.
240

Design Optimization Of Llc Topology And Phase Skipping Control Of Three Phase Inverter For Pv Applications

Somani, Utsav 01 January 2013 (has links)
The world is heading towards an energy crisis and desperate efforts are being made to find an alternative, reliable and clean source of energy. Solar Energy is one of the most clean and reliable source of renewable energy on earth. Conventionally, extraction of solar power for electricity generation was limited to PV farms, however lately Distributed Generation form of Solar Power has emerged in the form of residential and commercial Grid Tied Micro-Inverters. Grid Tied Micro-Inverters are costly when compared to their string type counterparts because one inverter module is required for every single or every two PV panels whereas a string type micro-inverter utilizes a single inverter module over a string of PV panels. Since in micro-inverter every panel has a dedicated inverter module, more power per panel can be extracted by performing optimal maximum power tracking over single panel rather than over an entire string of panels. Power per panel extracted by string inverters may be lower than its maximum value as few of the panels in the string may or may not be shaded and thereby forming the weaker links of the system. In order to justify the higher costs of Micro-Inverters, it is of utmost importance to convert the available power with maximum possible efficiency. Typically, a microinverter consists of two important blocks; a Front End DC-DC Converter and Output DCAC Inverter. This thesis proposes efficiency optimization techniques for both the blocks of the micro-inverter. iv Efficiency Optimization of Front End DC-DC Converter This thesis aims to optimize the efficiency of the front end stage by proposing optimal design procedure for resonant parameters of LLC Topology as a Front End DC-DC Converter for PV Applications. It exploits the I-V characteristics of a solar panel to design the resonant parameters such that resonant LLC topology operates near its resonant frequency operating point which is the highest efficiency operating point of LLC Converter. Efficiency Optimization of Output DC-AC Inverter Due to continuously variable irradiance levels of solar energy, available power for extraction is constantly varying which causes the PV Inverter operates at its peak load capacity for less than 15% of the day time. Every typical power converter suffers through poor light load efficiency performance because of the load independent losses present in a power converter. In order to improve the light load efficiency performance of Three Phase Inverters, this thesis proposes Phase Skipping Control technique for Three Phase Grid Tied Micro-Inverters. The proposed technique is a generic control technique and can be applied to any inverter topology, however, in order to establish the proof of concept this control technique has been implemented on Three Phase Half Bridge PWM Inverter and its analysis is provided. Improving light load efficiency helps to improve the CEC efficiency of the inverter.

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