This thesis proposes an automated method for generating, executing, and assessing an interlocking test in a digital substation using a Python script designed for that specific purpose.

The goal is to expedite the process of performing the factory acceptance test (FAT) and the site acceptance test (SAT) of a substation automation system (SAS). This work requires a good understanding of the IEC 61850 standard, which is the international standard applicable to protection, automation and control systems (PACS). An account of the relevant parts from this series is therefore given, in addition to an overview of the benefits of digital substations in general.

The workflow for automatically generating a test case is based on previous work that made it possible to execute and assess an interlocking test automatically but not to generate a test case automatically for this purpose. Therefore, that is the main intention of the thesis.

It is done by having knowledge of the underlying interlocking logic of the system subject to test. From this logic, a test sequence can be created, where the position of the various switchgear is changed sequentially. This and the signal addresses for these devices are needed to generate a test case.

For additional robustness, the script can cross-check the signal addresses provided with the signal addresses in the substation configuration description (SCD) file and validate the final test case generated using a suitable schema. It is furthermore capable of generating a test case irrespective of the number of test steps, switching devices, and bays present in the substation.

A test file generated using this script is further validated by executing the test it describes in the SAS laboratory at the Norwegian University of Science and Technology (NTNU). This test was carried out remotely to showcase the possibilities of IEC 61850, which can be valuable for distant or offshore substations. Another benefit of this workflow is that it allows for the simulation of all devices of the test except for the device under test (DUT). This is particularly useful during commissioning if all devices have not yet been delivered or installed. In this case, the missing equipment can be compensated for by simulating the signals expected from these devices.

The final assessment of a test case relies upon the presence of the IEC 61850 LN (Logical Node) CILO (Control Interlocking). The output of this LN controls the interlock status of the DUT. If the DUT is allowed to operate, it sends a release signal or, alternatively, a blocking signal. In addition to this, information is gained based on the position of the switchgear under test to check that the CILO signal is consistent with the actual switchgear control command. This control command is known as the AddCause in IEC 61850 and will provide additional information on whether or not the DUT is interlocked.

Finally, the thesis will describe ongoing work in the IEC 61850 that could lead to a more streamlined approach and touch on the utilities' attitude towards SAS.

This thesis investigates the impact of geometric, material, and operational parameters on the electromagnetic fields (EMFs) emitted by submarine power cables, particularly those used for offshore wind power transmission. The study is essential due to the growing deployment of offshore wind farms and the corresponding need for efficient submarine power transmission systems, combined with ecological concerns. The primary focus is on high-voltage alternating current (HVAC) cables, commonly used to connect offshore wind farms to the onshore grid. The rapid expansion of offshore wind power has highlighted significant ecological and environmental concerns, especially the effects of EMFs on marine life. Species such as elasmobranchs (sharks, rays, and skates) are highly sensitive to EMFs, making this an important area of research. The objective of this thesis is to develop guidelines for modeling EMFs from submarine power cables to aid ecological research, focusing on establishing effective parameters for EMF emission models. A literature review has shown that EMFs can impact marine animals’ navigation, predator-prey relationships, and embryo- genic development. Elasmobranchs, in particular, are vulnerable due to their sensitivity to EMFs. The review highlights the necessary accuracy levels for EMF models, focusing on HVAC cables. Starting with the basic physics including Maxwell’s equations, the Biot-Savart law, and the Lorentz force, followed by an outline of HVAC cable and transmission system design parameters, an understanding was created of the electromagnetic phenomena occurring in a submarine power cable. It was concluded that modeling EMFs requires considering current distribution along the conductor and metallic sheath, and the local interactions between cable components that result in shielding of the EMFs. A method from literature was used for predicting the longitudinal distribution of current along the conductor. The current distribution was affected by voltage and current transmission requirements, impedance, and the capacitive and inductive properties of the phases as well as reactive power compensation. Analyzing these parameters showed that all are crucial for accurate EMF modeling, as parameter changes within realistic ranges could result in differences over 10%. A significant part of this thesis examines the intensity of the metallic sheath currents. Modern HVAC cable designs use conductive polyethylene layers around the metallic sheaths, creating an electrical interface between them. This was conventionally assumed to dissipate circulating currents in the sheath, but this thesis questioned this belief. It was proven that some circulating currents remain and that induced currents were even unaffected by the conductive interface. The induced currents in the metallic sheath are shown to only be influenced by the conduction current and its design parameters, inductance, and resistance per unit length. Testing on the Borssele Alpha cable showed that sheath current for all standard operations was more than 12% of the conduction current. An analysis of the local impact of various design and operational parameters on EMF emissions was conducted using COMSOL Multiphysics. The Borssele Alpha 1 cable design served as a standard test case. The analysis highlighted the importance of the metallic sheath and even more so, the armor layer. The steel armor layer created a path of low reluctance, with geometric parameters and permeability playing significant roles. The effect of twist in the phases and armor wires on field emissions was also shown. The lay-length of the phases played a large role due to its effect on destructive interference between emissions of different phases. The armor lay-length had a considerable impact as well, possibly affecting the reluctance of the armor layer. The parameter analysis also confirmed the validity of an ultra-shortened section length in COMSOL, greatly reducing simulation time without impacting results. This research provides insights for developing accurate EMF emission predictions, aiding biologists and ecologists in evaluating the environmental impacts of offshore wind power infrastructure. This can guide the development of mitigation strategies and support sustainable expansion of renewable energy sources. Recommendations for future research include experimental testing of the sheath current model, further development of the transmission line method for the metallic sheath and developing better mitigation strategies. Unrelated to the main question is that in thermal analysis of comparable submarine power cable designs, the induced current must be incorporated, as it was unclear if this is the case. The findings of this thesis can significantly contribute to the sustainable growth of offshore wind power by addressing ecological concerns and improving the understanding of EMF effects on marine life.

This thesis explores a Travelling Wave (TW) parameter fitting-based approach for both fault location and protection in a multi-terminal High Voltage Direct Current (HVDC) network. Utilizing a three terminal HVDC network model within a Real-Time Digital Simulator (RTDS) environment, a custom parameter fitting control component is developed using the Adaptive Multi-step Levenberg-Marquardt (AMLM) algorithm. For fault location, the methodology analyzes the line-mode backwards travelling voltage wave (Vb1) following an internal DC cable fault. Despite the successful integration of the AMLM parameter fitting algorithm into the real time environment, the achieved average absolute error of 9.80% (29.4 km) for faults spaced 50 km along a 300 km cable was above the acceptable threshold, rendering the proposed
method impractical for precise fault location. Improvements through specific signal truncation and optimal cable parameter selection reduced the error to 5.15% (15.45 km), which remains insufficient for practical applications. In contrast, the TW parameter fitting method proves highly effective for fast and fully selective protection. The protection scheme accurately discriminates between internal and external faults using the Vb1 signal and determines fault types through Vb0 signal analysis. Extensive testing revealed a fault detection rate of 100%, with an overall accuracy of 99.91% for fault resistances up to 200Ω. Severe internal faults are isolated in 1.68 milliseconds, while non-severe internal faults are typically isolated in 3.84 milliseconds. The method completely eliminates relay deadzone, providing robust performance even under noisy conditions with an accuracy of 99.85% for faults with an impedance up to 50Ω. These findings highlight the potential of the TW parameter fitting approach to significantly enhance the reliability and promptness of fault isolation in HVDC systems, while offering insights into the challenges and limitations of fault location accuracy on a real time platform.

Unwanted breakdown of insulation is one of the primary challenges affecting the reliability of power systems. Liquid insulation is commonly used in power grids and subsea installations due to its preferred qualities, such as heat transfer and safety. Some insulating liquids have been available since the earliest times, and some have been proven to be harmful to humans, animals, and the environment. Consequently, the search for better candidates has always been ongoing. Unfortunately, the knowledge of the quality of the insulating liquids is insufficient since numerous phenomena related to electrical discharge and breakdown in insulating liquids happen unexpectedly, often surprising the personnel involved. Therefore, gaining a deep understanding of the breakdown physics of these liquids and mechanisms leading to the degradation of their dielectric properties is crucial. This understanding ensures that the new replacements are suitable for specific equipment. Partial discharge (PD), as one of the initial stages before breakdown and a major player in ageing the insulators, is the main focus of this work. One way to monitor a liquid’s insulation quality is through the Partial Discharge Inception Voltage (PDIV)
level. Based on PDIV measurements, there are defined standards, such as IEC 61294. This work is focused on investigating the behavior of different types of liquids under the AC voltage stress above and below the PDIV level to determine if the defined standards reflect the dielectric characteristics of each liquid properly. Three liquids have been examined, including two candidates from commonly used insulating liquids in electrical installations. Tests are performed in a needle-plane geometry under high-voltage AC stress. The same liquids and geometry have been used multiple times in previous studies under lower frequency AC voltage, yielding unexpected results. Therefore, this study aims to investigate deeper by testing the liquids at higher frequencies and comparing observations with previous results. The experimental setup used for this work includes a 20 kV resonance voltage source, and the needle-plane gap distance is 20 mm. The current flow from the plane to the needle is mostly capacitive in the range up to 100 nA, but space charges are proved to play a major role in the conductive component of the current. PD behavior has been found to relate to molecular structure and, in some cases, to the previous stresses, likely due to residual ions remaining from previous cycles. The presence and nature of space charges have been investigated carefully by testing liquids at higher frequencies below and above the PDIV level. Further, the test setup was facilitated, and half-cycle voltages were applied to involve only one polarity of space charges, and the differences were observed. Another part of this work involved the optical PD measurement method, which utilized two photomultiplier tubes (PMTs) and a coincidence circuit to filter out ambient dark noise. This method was employed alongside the well-known charge acquisition method to detect the initial PD pulses in the liquid. The results demonstrated a noteworthy difference between the two methods, prompting further investigation.

Drones -- small (or not so small) remotely controlled flying devices -- are seeing rapidly increasing use in many fields of application and human activities ranging from recreation, competitive sports, last-mile logistics, espionage, exploration, to media production, and even warfare. The abundance of these devices brings with it the risk of them becoming an audible nuisance due to the high pitched noise produced by their surface-mount (SM) PMSMs.
The acoustic noise produced in these motors is the product of multiple factors, but chief among them is the vibration of the motor's external shell, which is the stator for internal rotor type motors and the rotor for external rotor type. This shell vibrates in various oscillation modes as a result of the magnetic forces acting on it, which are an inevitable result of the motor's internal magnetic field and the armature currents that produce them.
This motivates research effort into reducing this noise through modulation or control strategies employed by the inverter powering the motor. In order to develop a control model, first the motor itself must be understood. In this thesis, the electromagnetic aspect of surface-mount-PMSMs will be developed, i.e. an analytical model will be established of the air gap magnetic field in SM-PMSMs.
First, the armature reaction field for arbitrary winding types will be derived, followed by a detailed derivation of equations typically used to model the rotor magnets in SM-PMSMs. A derivation of the effect of stator slotting on the air gap magnetc field will be provided, and concluded with a combination of the three previously mentioned aspects, and the dimension of time will be incorporated in the model.
Accompanying this thesis will be a set of MATLAB code that will be made publicly available for research and instruction in academia.

As society advances, the demand for sophisticated motor technologies grows. In particular, high-precision modular servo systems have become indispensable in addressing complex real-life challenges, ranging from automation in manufacturing to precision control in robotics. The GEMS project is dedicated to developing an online course that offers detailed tutorials alongside affordable educational hardware, making advanced learning opportunities more accessible to mechatronic students.

This thesis begins with a review of motor technology advancements and their suitability for servo systems. In line with the educational GEMS project’s goal of cost-effectiveness, a permanent magnet brushed direct current (DC) motor was chosen as the core device for electromechanical power conversion due to its simplicity, ease of control, and low cost. The drivetrain system incorporates 3D-printed gears, ensuring affordability and easy replication. For feedback control, two small magnets combined with magnetic Hall-effect sensors function as low-resolution quadrature encoders, offering essential functionality while minimizing costs.

The drive system consists of four key modules: power, sensing, communication, and motion control. Each module's printed circuit board (PCB) functions are detailed based on schematic analysis. The thesis focuses on the motion control module, which is responsible for managing the motor's performance, including speed, position, and torque control. It deals with the low-resolution encoder feedback and implements the control algorithms.

A Simulink model was developed to simulate the DC motor with a 3D-printed drivetrain gearbox. Conventional cascaded PI control is applied, with a current loop as the inner loop and a speed/position loop as the outer loop. To address speed measurement challenges posed by low-resolution quadrature encoders, an encoder tracking algorithm was implemented in the Simulink model, enabling closed-loop control. Finally, the control firmware, based on the Simulink model, was developed in C for the ESP32 microcontroller. Prospective future work is also outlined.

Airborne wind energy (AWE) is a wind energy technology in the development phase consisting of tethered kites that reach high altitudes consisting of relatively stable wind speeds. While no company has yet reached the point of commercial viability, a variety of AWE technology concepts and designs have been under development and are currently at low- to intermediate technology readiness levels. When AWE systems are grid-connected a power smoothing element is needed to smooth the oscillating power output of the system for the grid. In this thesis, a framework for modeling a grid-connected hybrid power system (HPS) consisting of AWE and batteries participating in the day-ahead market (DAM) has been developed in the MATLAB environment. The framework incorporates an existing AWE performance and cost model with power smoothing performance, battery degradation, and DAM storage arbitrage. Multiple use case scenarios are evaluated to test the economic performance of multiple configurations of the HPS. These scenarios are; an AWE system with an ultracapacitor (UC); an AWE system with batteries; a battery system operating in DAM arbitrage and an AWE system with batteries operating in DAM arbitrage. The configurations were evaluated using multiple performance metrics, primarily the internal rate of return (IRR) as a metric for economic performance. A simulation of the HPS participating in storage arbitrage was then used to determine the economic viability of using the battery system for both power smoothing and arbitrage. The arbitrage behavior of the storage system was determined by a heuristic selling logic model developed to simulate the combined use of a storage system for power smoothing and arbitrage. The arbitrage logic is based on price volatility and power smoothing constraints.

The battery power smoothing system resulted in significantly lower system cost overall and consequently an increase in profitability (IRR of 12.37%) compared to the more expensive UC power smoothing configuration (IRR of 10.20%). The HPS configuration with batteries used for power smoothing combined with arbitrage showed a marginal increase in economic performance with an IRR of 12.43%. This showed a potential value increase of the system when using excess capacity arbitrage but not at a significant rate.

Insulated metal substrate (IMS) printed circuit boards (PCBs) are an attractive alternative to conventional FR4-based PCBs and power modules due to their good thermal performance, low cost, and compatibility with the reflow soldering processes. In this thesis, the dielectric performance of IMS PCBs is characterised to validate their use in high-voltage power electronic applications and ensure that an acceptable lifetime and reliability can be reached. In particular, the high-frequency degradation of the dielectric is investigated.

The IMS dielectric was characterised using breakdown tests with various voltage waveforms and frequencies to closely approximate their use-case in power electronic converters. Two high-voltage generators were designed and realised to generate high-frequency square-wave and sinusoidal waveforms. In addition, diagnostic tests were performed to identify the effect of electrical ageing on the dielectric properties.

he designed high-voltage test sources allowed for ramp breakdown and lifetime tests up to 100 kHz and 10 kVpk. These tests showed that the dielectric degrades extremely fast under high-frequency voltage stress, most likely due to localised high partial discharge activity and electrical treeing. As a result, no reasonable lifetime can be expected when operating above the discharge inception voltage. For thick dielectrics (>100 µm), surface discharges are the dominant degradation mechanism with an inception voltage of 2.4 kVpk. The maximum nominal voltage should be limited to approximately 1.5 kVpk to ensure the reliable operation of the IMS PCBs.

This research analyses the potential of Electrical Signature Analysis (ESA) as a means for condition monitoring of mechanical defects of induction motor driven thruster assemblies in the maritime industry. This is done by measuring the three phase current and voltage of three thrusters, with different health conditions, of a marine vessel sailing at different speeds. In this data, the mechanical behaviour of the machines is detected by plotting the frequency spectra of various electrical parameters, such as complex current and torque. After successfully identifying mechanical behaviour and defects, a suggested approach for the implementation of ESA as a means for condition monitoring is presented.

Distributing power and data around a garment is a common problem in sensor enabled e-textiles, as connecting separate electronic subsystems together using connectors and wires has proven to be unreliable and cumbersome. In this work a solution is presented that will eliminate the connectors by using two pairs of short-range wireless inductive links. The proposed system is able carry power from one node to the next, while at the same time facilitating data transfer between the nodes. In this work the double inductive link is analysed, and a novel compensation topology is presented. A modified class-E amplifier is proposed to generate a carrier signal, improving the system settling time. Using a placeholder data protocol the system is able to transmit 62mW of regulated power to an external load at a total efficiency of 7.3%, while simultaneously transmitting data at a rate of 8.5kbit/s. Without data transmission it is able to deliver 185mW of DC power at 6.09V unregulated, at an efficiency of 23%. The system is also shown to be capable of handling a maximum bitstream of 240kbit/s.

In 2019 the European Aviation Environmental Report stated showed a relative increase in CO2 emissions of 16% compared to 2005 to 2017. It also stated that an increase of 42% is expected according to current models. Aviation is thus a big sector of the global warming problem. The solution to this is to go full electric. There are already more electric aircraft who decline the use of fuel for aircraft. This project thus attempts to design an electrical architecture for one of these airplanes. This thesis in particular shows the power demand for most the loads on the plane using mostly linear extrapolations, and voltage to current ratio on the system. It also talk about a state of the art electrical motor, and its characteristics, estimated to be available by the year 2038

In this thesis, the accuracy and efficiency of Magnetization State (MS) tuning in Tunable Magnet Actuators (TMAs) is investigated. TMAs are developed to improve thermal stability in quasi-static precision actuation applications. First, the operating principles of TMAs and limitations in previous work are discussed respectively. It is found that the linearization and simplification of magnetic hysteresis limit the accuracy and efficiency of the tuning process. Subsequently, a history dependent tuning algorithm and a generalized non-linear hysteresis modelling methodology are proposed. The tuning algorithm minimizes the energy loss by adhering to the hysteresis properties described by Madelung’s rules. The hysteresis model uses measurement data to accurately calculate the applied field Corner Point (CP). Finally, the tuning algorithm and hysteresis model are experimentally validated for MS tuning of an AlNiCo-5 Permanent Magnet with an RMSE of 5.8 mT and theoretical tuning energies are reduced by as much as 86%.

Perovskite/Silicon tandem cells are gradually becoming more promising in the field of photovoltaic technology since they have already surpassed the theoretical power conversion efficiency (PCE) limit of single junction (SJ) silicon cells (~30%), while they can be commercially compatible. Several architectures of Perovskite/silicon devices were proposed. The most known of them are four terminals tandem (4TT) and two terminals tandem (2TT). Which are well researched and have already surpassed the highest efficiency achieved by SJ silicon cells. On the other hand, 3TT is less known architecture which have received less attention in research than 2TT and 4TT but seems to combine the advantages of both and eliminate their disadvantages. Although of the few research done on 3TT, they revealed great potential of achieving high efficiency. Yet it is still practically challenging to design and fabricate stable 3TT devices that bring 30% PCE’s goal to reality. To continue unveiling the potential of 3TT perovskite/Si device, more research needs to be done in areas that haven’t been investigated before. And that was the target of this project.
The 3TT device structure proposed in this work is a perovskite top cell on a c-Si IBC bottom cell. And the focus of the project was to investigate and optimize the design parameters of the perovskite top cell as well as the IBC bottom cell to improve the overall efficiency of the tandem device using 2D modelling. To achieve these Objectives, a 2-D simulation model template was built for the mentioned tandem device with the help of Sentaurus TCAD. Further, the model template has been validated. Subsequently, the validated model was used to conduct a comparison between the proposed 3TT device and an identical 4TT device to examine the compactivity of the model with other tandem configurations. This has shown that the 3TT model has performed as good as the 4TT model. Both models showed capability of achieving efficiency beyond 30%.
Then, the performance of the 3TT model was examined under different thicknesses of Perovskite layer. This revealed that the 3TT device has the highest efficiency when the perovskite layer has a thickness between 0.5 - 1.2 µm where efficiency higher than 30% can be achieved.
The next step was to investigate and redesign the IBC bottom cell to improve the 3TT performance. First, the device performance under different pitch values in the IBC bottom cell was examined. It was found that the lower the pitch is, the higher the performance becomes. It was also found that the pitch value doesn’t influence only the bottom cell but also the top cell. Which makes the performance of 3TT device more sensitive to pitch values than the SJ IBC cell. Second, the rear emitter to base ratio in the IBC bottom cell was investigated. Which showed that the emitter/base ratio has less influence on the 3TT behavior when the pitch value is within or less than the range of the diffusion length of the bulk material. But the influence of the ratio grows up when the pitch is higher. The 3TT device has its peak performance when the ratio is between 2:1 to 4:1.
After that, the tandem model was redesigned to corporate all the outcomes that was found in previous steps. This resulted in several scenarios based on best parameters to design 3TT models with the best outcome. Four scenarios have been suggested where each of them can achieve PCE higher than 31.5 %.
Finally, we have studied the effect of surface recombination on the performance of the 3TT device. Which revealed that most of surface recombination losses are coming from the interfaces between perovskite layer and ETL or HTL layers. Therefore, if these surface recombination losses are suppressed, that will lead to a PCE higher than 33 %.

This thesis describes the design of a CMOS magnetic field sensor system for measuring electronic currents. A hybrid system, using Hall plates and a pick-up loop is chosen to obtain improved performance compared to conventional Hall based magnetic field sensors. The pick up loop enables to reduce the current consumption and increases the bandwidth of the system. The design of the pick-up loop and readout amplifier are described in detail. Simulation results of the pick-up loop signal path offer a factor 10 increase in bandwidth using 24% less current compared to a system consisting of two Hall plate channels.

Given the urgency to shift to a cleaner energy mix, offshore wind energy is bound to be quickly deployed on a large scale in the next years. In order to meet the Paris Agreement, the current role-out rate of wind energy in the North Sea, that is 2 GW/year, needs to be increased to an average value of 7 GW/year over the period 2023-2040. This rapid increase of the share of uncontrollable, renewable sources in the energy mix raises a certain number of challenges, among which sustaining energy balance and transient stability. To organise the large-scale deployment of offshore wind in a strategic manner, the concept of hub-and-spoke has been introduced. It envisages modular offshore renewable power generation clusters (a.k.a. offshore hubs) designed to be easily and safely operated and interconnected.

Dealing with large power fluctuations constitutes a major challenge for each offshore hub. The variability of power supply needs to be mitigated through the integration of storage solutions. Offshore power-to-gas conversion for storage purposes has been widely investigated in the literature, under techno-economic or power balance points of view. However, detailed analysis of the effective connection of large scale electrolysers in offshore hubs are missing.

This thesis proposes a real-time simulation model of a 2 GW offshore hub integrating electrolysers in order to investigate their impact on the dynamic active power management of the hub. Two locations for the connection of the large-size electrolysers are studied: i) connection of an electrolyser to the AC common bus of the hub and ii) connection of electrolysers to the DC link of the back-to-back converter of each Type-4 wind turbine of the hub. An Electromagnetic Transient (EMT) simulation based analysis, necessary to capture the fast dynamics of the zero-inertia hub, is performed under different severe disturbances, such as a three phase fault and sudden large wind speed fluctuations.

In a second part, the thesis investigates the connection of the hub to the shore via a bipolar High-Voltage Direct Current (HVDC) link. It has been shown in the literature that bipolar links are more reliable than monopolar ones, as they can still be operated to transfer half of their nominal capacity in case of failure of one cable or converter. The work of this thesis is focused on developing and implementing a power sharing strategy between the two Modular Multi-level Converters (MMCs) constituting the offshore terminal of the link.

It was found in this thesis that both investigated locations for the connection of the electrolysers can be beneficial in different ways. Connected at the AC common bus, the electrolyser can provide centralized ancillary services, while an electrolyser connected locally at the wind turbine can consume the power generated during an islanding event. Regarding the power sharing in the HVDC link, two different strategies were developed, both enabling to unload one of the poles of the link. Further studies should be carried out to provide in-depth understanding of the potentialities of the two methods.

Green hydrogen can be produced from various renewable energy sources like PV, wind, geothermal and biomass. Especially PV or wind sourced hydrogen production systems are becoming more prevalent as a solution to produce green hydrogen, owing to their regional abundance. In this master thesis project, a PV-grid powered electrolyser shall be taken into consideration. The electrolyser is an equipment that produces hydrogen through electrolysis. Here, an alkaline electrolyser is taken into consideration, which is a DC load and hence, it requires a rectifier to convert the AC power from the grid and from the PV plant (DC PV power will be converted to AC through an inverter) into DC power. The amount of hydrogen produced is proportional to the amount of current flowing into the electrolyser. As the electrolyser operates, the process of electrolysis will, more often than not, produce heat. The heat produced during electrolysis, along with the ambient conditions, will result in variation of the temperature of the electrolyser. Some systems make use of a thermostat to control the temperature of the electrolyser whereas some employ a cooling system to extract heat and utilise it to perform useful work. If there is no system to control or maintain its temperature, the electrolyser is bound to have varying temperature while it is operational. This research aims to develop a control strategy for a PV-grid powered electrolyser to ensure the optimal operation of the electrolyser despite its varying temperature. The need for such a control strategy for the electrolyser rises due to the dependence of the I-V characteristics of the electrolyser on the temperature. As the temperature of the electrolyser increases, the I-V curve shifts in such a way that a given current value will be produced at a lower value of voltage. Since the amount of hydrogen produced depends on the amount of current flowing into the electrolyser, the control strategy aims to maintain the input current to the electrolyser at the rated value irrespective of the change in the temperature of the electrolyser. The control strategy is tested on Simulink with the help of an electrolyser emulator into which data is fed through a look-up table. Real-time data for irradiance and ambient temperature has been used to perform day-long simulations. Based on the results obtained, the average efficiency of the converter was found to be 93.88%.

The need for efficient power transfer at lower cost is a common requisite for any power con­verter system. When considering the application of wireless power transfer for Electric Vehicle(EV) charging, higher efficiency and lower cost can be achieved by reducing the number of stages of the system at the grid side. This thesis explores the feasibility of an AC/AC matrix converter for wireless power transfer application. To begin with, different existing topologies of the converter module are discussed and qualita­tively compared to the matrix converter. Subsequently, the plausibility of single stage matrix converter is verified through simulation. Due to the converter’s high switching frequency, this configuration results in injection of higher than permitted harmonic content into the grid. Fur­thermore, the feasibility of three phase matrix converter and its advantages are studied. The converter working is verified through simulation. To make the grid current less distorted, closed­ loop control is introduced. This control con­sists of an inner current loop and an outer voltage loop which are both implemented using a PI controller. To conclude, three phase matrix converter acts as a plausible solution for the desired applica­tion. Furthermore, the control ensures balanced grid current and desired output power.

As electric vehicles are quickly taking over the automotive industry, electric airplanes are also starting their upswing. With air travel and transport in general being a large polluter of CO2 gases, the transition to electric flight becomes more prominent every year. This transition is starting small with non-commercial airplanes. Several companies are starting with development of eVTOLs, electric Vertical Take-Off and Landing vehicles. The idea behind them is that they can easily move into and out of the city through the air, speeding up transport and travel in urban areas while keeping CO2 emissions at the vehicle level at zero.
This thesis, together with two other theses, will elaborate on the design of such an eVTOL. Its design is created by looking at the layout of the propellers, the wings and the fuselage and the internal layout is composed by working out the electric drivetrain from the energy storage to the electric motors and by drafting up the control systems. In specific, this thesis dives into the external design and the internal electric energy storage. It does this by settling on a design and calculating certain specifications, like wing area and propeller and fuselage size. From there the necessary powers and energies are calculated. With these powers and energies, a battery pack is designed together with a battery management system and a charging system. The other two theses will design the propulsion system and the control system of the eVTOL.
The result of the thesis is a theoretical design that states the possibilities of Lithium-Sulfur cells inside an eVTOL. An efficient tandem wing design with fixed wings and fixed rotors makes sure there is a healthy balance between the maximum power and total energy needed to take off vertically and fly 125 kilometers. With the Lithium-Sulfur cells a battery pack is made with its accompanying battery management system that monitors and manages the cells' characteristics. Next to the battery pack, theory on charging and a simplified charging simulation has been done to show that charging in 15 minutes should be possible by the time the eVTOL enters into service.

In this thesis, a closer look will be taken into the design of a propulsion system of an eVTOL (electric Vertical Take-off and Landing aircraft). The primary goal of the eVTOL is to maximize the payload for a given maximum take-off weight and the eVTOL has to go into service in 2030. To make an as light weight as possible propulsion system, an investigation will be done for the propeller length and the number of rotors, which is present on a given eVTOL design. In addition to this, different drive choices will be discussed and an optimal drive choice will be made. For this drive, a closer look will be taken in efficiency optimisation. From these parameters a design example will be given using the current state-of-the-art drive technology. In addition to this possible future drive, developments will be taken into account.