The aerospace and marine sectors are currently using or actively considering the use of DC networks for electrical distribution. This has several advantages: higher VA rating per unit volume of cable and ease of generator connections to the network. In these systems the generators are almost exclusively ac generator (permanent magnet or wound field synchronous) that are linked to the dc network via an electric converter that transforms the ac generator output voltage to the dc rail voltage.The main objective of this project is to develop a Homopolar DC Generator (HDG) that is capable of generating pure DC voltage and could therefore remove the need for an electric converter and ease connection issues to a dc electrical distribution network. The project aim is to design, build and test a small technology demonstrator, as well as electromagnetic modeling validation.In Chapter 1, the initial generator concepts proposed to fulfill the aforementioned requirements of DC generator are presented, as well as an obscurity in electromagnetic induction law faced at the beginning of this project. Also the advantages, disadvantages and different applications of Homopolar DC Generators are covered in Chapter 1. In Chapter 2, Faraday's law of induction and the ways of using it properly are discussed using some example. The preliminary design calculations to construct the prototype HDG are presented in Chapter 3. Also the prototype construction and assembly procedure are discussed in this chapter. In this project, magnetostatics and current flow Finite Element (FE) simulations were used to assess the prototype HDG. In Chapter 4, the results of 2D and 3D-FE simulation are presented; furthermore the limitations of the FE simulations to assess the HDG performance are included. In Chapter 5, the results of the practical tests are demonstrated and assessed, as well as comparison between some of the results obtained practically and those obtained using FE-modeling. Using sliding contacts in the HDG is obligatory so some definitions corresponding to electrical contact resistances are given in Chapter 5. Final chapter is conclusions including the results assessments, future works to design, simulation and construction of the HDG.

Projektet går ut på att ersätta den befintliga styrningen av en DC-generator för 1200 kV med en fjärrstyrning från kontrollrummet via optolänk. Den nya styrningen ska utgöras av ett PLC-system (Programmable Logic Controller) som manövreras med hjälp av ett HMI – Human Machine Interface. Bakgrunden till projektet härrör från att den befintliga styrutrustningen är opålitlig samt styrs i en farlig miljö. Rapporten går igenom hur befintlig styrutrustning fungerar samt dess ingående komponenter, hur ett PLC-system fungerar med dess bakgrund och olika programmeringsspråk. Även programmeringen och byggnationen av det nya systemet avhandlas. I slutet av rapporten ges en genomgång av de provkörningar som utförts för att säkerställa att alla funktioner fungerar som tänkt. Resultat av provkörningarna ges och diskussion förs kring projektet. Projektet är utfört åt högspänningsgruppen på RISE i Borås som använder generatorn bland annat vid kalibrering av spänningsdelare. Det nya styrsystemet innefattar alla av den tidigare styrutrustningens funktioner och några nya funktioner så som överströms- och överspänningsskydd vilka slår från spänningsmatningen om dessa begränsningar överskrids. Att styrutrustningen nu är placerad i kontrollrumsmiljö gör att operatören kan hantera utrustningen utan att vara i närheten av farlig spänning. / The report aims to replace the current control equipment for a DC-generator for 1200 kV by remote control from control room through optical fibre link. The new control will be a PLC system controlled by a HMI – Human Machine Interface. The background to the project is that the existing control equipment is unreliable and controlled in a dangerous environment. The report shows how the current control equipment works and its constituent components, how a PLC-system works with its background and different programming languages. This report will also describe how the programming and building of the hardware are done. In the end of this report are going through a test run to confirm that the system is working properly. Result of the test run are given and some discussion. The project is initiated by the high voltage group at RISE in Borås, who are using the DC-generator for instance while calibrating voltage dividers. The new control system contains all of the functions from the earlier control system but also some new functions such as overcurrent and overvoltage protection who turns off power supply if the limits are exceeded. The control system is now located in the control room so that the operator can use the system without being close to high voltage.

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.