BAE Systems Hägglunds använder säkringar och kontaktorer eller reläer för deras 28V-system. Kostnaden för dessa är höga och dem är utrymmeskrävande. Syftet med detta projekt var att utveckla den befintliga elcentralen. Målet var att konstruera ett system baserat på halvledarrelä med strömmätning samt säkerhetsfunktion. En prototyp konstruerades med en spänningsregulator, fyra optokopplare, två kylflänsar, och två stycken transistorer. Resultatet visade att prototypen tolererade strömmar upp till 70A på en 24V-spänning. Prototypen tolererade sannolikt högre spänning och ström, men detta kunde inte verifieras.

A sedentary lifestyle can induce health related problems including pressure ulcers. Pro­longed sitting inadequacies constitute a risk for pressure ulcer to many individuals, in particular people with disabilities and re­duced mobility. The measurement of distributed pressure and detection of irregular sitting postures are essential in prevention of the risk of developing pres­sure ulcers. In this thesis, a screen-printed pressure sensor for a large area is presented, with the objective of measuring the distributed pressure of a seated per­son in a wheelchair. The conductors and interdigital patterns are printed with silver-based ink. A blend of a non-conductive and a low resis­tive ink is used for customized resistance for an optimal sensing range of the pressure sensor. The effect of moisture and temper­ature are realized in an environment chamber. For characterization, other key performance tests such as repeatability, drift and flexibility are carried out. The surface morphology is carried out for structural analysis of printed samples. The sensor data is acquired and processed using an 8-bit ATmega-2560 micro­controller and wirelessly transmitted to a PC for post-processing, storage and analysis. For real-time data presentation of dis­tributed pressure points, a GUI has been developed to display the values ob­tained from the large area sensor. The detection of four sit­ting pos­tures; forward leaning, backward leaning, left leaning and right leaning along with a normal sitting posture is attained. An analysis for stretchable printed tracks has been conducted to investigate the changes in electrical resistance using elon­ga­tion tests, surface morphology and EDS. The optimal curing time and tem­per­ature were investigated to manufacture stretchable conductive tracks. In summary, the contributions in this thesis provides an effective approach regarding pressure distribution measurement and recognizing irregular sitting postures for wheelchair users. / <p>Vid tidpunkten för framläggningen av avhandlingen var följande delarbete opublicerat: delarbete 3 (accepterat).</p><p>At the time of the defence the following paper was unpublished: paper 3 (accepted).</p>

This thesis carries out an analysis of PV panel installations in the region of Östergarnslandet, situated in the Swedish island of Gotland. A low-voltage grid of 0.4 kV in the region is examined with the help of software Open DSS. This is done with the data provided by the distribution grid owner, Gotlands Elnät AB (GEAB). The potential impacts created by the PV installations in terms of exceeding currents, voltages and harmonics are assessed and thereby the hosting capacity of Solar PV in the houses and on the whole grid is studied.   Moreover, a theoretical review of the Smart Energy Management System (SEMS) is investigated about the performance and the devices involved in the system. Also, a battery which is a part of SEMS is modelled, taking into account the production and consumption of a single household connected in the grid. The battery sizes for various PV installations at the home is suggested via NPV analysis with the intention to increase the self-consumption and to reduce the cost of the electricity bill. In addition, a survey is conducted in the region with support from the Department of Earth Sciences, Uppsala University Campus Gotland. The survey is made to determine the attitude of the people in Östergarnslandet towards an energy transition. The results show that the maximum amount that can be installed or the hosting capacity of solar in the studied grid is 120 kW. From the simulations, it shows that the impacts created by these PV installations do not violate the specified Grid norms. From the theoretical analysis, SEMS is found to be a better solution for energy management at homes. The performance study done shows that 33 % of the solar energy produced in the home is directly used at the time of production. The remaining energy is used for battery charging for the future supply of power and feeding to the grid. The battery modelled for 10- kW PV installation in the home is found to be 9-kWh and the same for a 15-kW installation. Meanwhile, for a 20- kW installation, a 15-kWh battery is found to be ideal from the study. The survey conducted in the region has turned out to be positive as people are supportive of the energy transition. The responders have marked photovoltaics as the prime option for investment in energy production which assures that it has a good future in the area.

Printed circuit boards are getting increasingly more complicated, as the electronics industry seeks methods to stay leading in modern technology. The competition to attain more economical solutions in terms of increasing complexity, integrity, optimum functionality, impose on design engineers to look for new horizons of solutions, then simulating and testing them theoretically and practically, before putting them into the labor market. In multi-layer boards, the issue of maintaining signal quality while transmitting it between different layers arises, it is a big deal, especially when dealing with RF signals, where each component through which the signal passes must be handled and designed with extreme accuracy to be received at output with a maximum matching with the input signal.  Vertical Interconnect Access (VIA) is the purpose of this thesis. The effect of geometrical shape and the dimensions such as pad, hole and clearance on the impedance due to parasitic capacitance and inductance, consequently on the reflection and attenuation of the passing RF signal passing through was investigated. Besides, a minimized reflection and attenuation was the aim of this project when signals with the frequencies of 2.4 and 5 GHz would pass through the VIA.

Supplying power to equipment always imposes a risk of damaging it. This risk is apparent in every application whether it be an industrial or a home appliance. One of these harmful occurrences is something like lightning which introduces a potentially harmful voltage in the system. To reduce the risk of damage significantly an over-voltage protection device is needed. Devices which deal with this problem are common in any electrical equipment and this report deals with the construction and evaluation of one such unit. The device or equipment needing protection in this case is an industrial underwater robot built by Ocean Robotics. In order for this robot to operate safely it needs several protective measures where an over-voltage protection system is one of them. This system provides protection against over-voltages appearing on the main cable supplying the robot, where the input voltage ranges from 200 to 600 volts. As the desired voltage output range from the over-voltage system is 250 to 350 volts it must be able to handle significant power in some cases. Due to the restrictions on functionality given by the contractor a novel way of achieving the goals was tested. The completed prototype can only dissipate 70 watts of power which is far from the required 1500 watts which was specified in the sheet of requirements. However, this system could be used to protect equipment with lower requirements for power handling capability and with added time and effort it could possibly meet the requirements for this project as well.

The brushless DC (BLDC) motor is a crucial component of our modern society and exists in a number of everyday items. It is an evolution of the conventional brushed DC motor. It has several advantages compared to the brushed DC motor including less maintenance and better control and precision of the rotary displacement. The goal of this project is to construct a BLDC motor made by 3D printed plastic parts and a control system using Arduinos. The purpose of the motor is that it will be used to demonstrate its functions and to educate engineering students at Uppsala University in electrical propulsion systems. Therefore the motor is designed with educative purposes and it is supposed to be easily controlled by an operator with clear indications of the internal workings. The finished motor consists of a stator which holds six electromagnets placed equally distanced from each other that makes up the tree different phases. In the middle of the stator a rotor is placed which holds four poles of permanent magnets with different polarity. The position of the rotor is determined and controlled by placing three equally distanced hall sensors in the stator. The signals from the hall sensors is sent to the Arduinos which in turn control the polarity of the electromagnets and make the motor rotate. The control system is contained in a plastic box with controls for different modes available for the operator and also indications of the position of the rotor and polarity of the electromagnets.

No description available.

This study is a result of master’s thesis in renewable engineering at Halmstad during spring term 2019.    The main contribution of the present work focuses on the development of a significant approach to identify best possible surfaces finish strategy in terms of solar battery charging. The aim of the thesis was to analyze, compare different battery charging method and implement PV cell system to run oil pump. I would like to emphasize my thanks Professor Jonny Hylander for his support guidance, opportunely posed questions that raised new lines of thought and motive to get good work on the thesis.     I would like to emphasis sincere thanks and gratitude to Mei Gong to guide throughout the thesis and support during urgent need.    I am grateful to other dissertation committee members for enlightening and inspiring discussion and their advice provided us guidelines in difficult times.    I would like as a final word of appreciation to thank the people of masters and research group at Halmstad University for their thoughtful comments and suggestion, which continually improve the quality of the dissertation

Detta examensarbete har genomförts i samarbete med Arvika Teknik AB. Rapporten undersöker två bostadsområden i Arvika lokalnät, där syftet är att ge vägledning om framtidens energibehov för elbilar samt om solceller kan hjälpa till och minska effekttoppar. Rapporten visar på att lokalnät i vissa fall har stora effektutrymmen som kan användas till laddning av elbilar. Ytterligare visas att solceller endast kan ha en marginell inverkan på effekttoppar. Utmaningarna för nätbolagen innefattar många andra faktorer än de som berörs i denna rapport. Rapporten ger viss vägledning men mycket arbete återstår. Problem med elbilsladdning kommer inte komma de närmaste åren men på sikt kommer det vara viktigt att utveckla metoder att styra elbilsladdningen. / This bachelor thesis is collaborated with Arvika Teknik AB. It’s an analyse of two local grids in Arvika. The purpose is providing guidance of future energy needs for charging of electric vehicles and whether photovoltaics is able to reduce power peaks. The report shows that some local grids have good capabilities to meet future power demand from charging electric vehicles. This thesis also shows that photovoltaics potentially has a fringe possibility to cut current power peaks. There are many more challenges for network operators than what is referred to here. Hence the report gives some guidance, but more research is needed. For both areas investigated, problems due to power shortages related to charging electric vehicles will not occur in the next few years. But as the number of electric vehicles rises it will be important to find methods to distribute the charging sessions.

This thesis investigates the possibility to automate testing of PCBs with a sensor system.  This PCB testing is today done manually by placing PCBs in a test fixture that determines its condition. This test requires an operator to wait for the test to complete and then place the PCB in the correct section. If this process can be automated time could be saved and the risk of mishandling PCBs could be reduced. A sensors system is made that consists of an Arduino with micro switches, hall effect sensors, a scanner and a LiDAR. The sensor system is designed to achieve a set of requirements that is needed for automation. The sensor system is meant to communicate with a robot that moves the PCBs within a test environment. This test environment is also designed in this project. For the system to communicate with a robot a program is made to inform the robot about placement of PCBs within the test environment. The final system is able to achieve the requirements set for automation but further investigation is needed to make this into a fully scaled automated system.