With the development of distributed energy resources (DER) and semiconductor devices, DC electric networks have become a competitive alternative to conventional AC-based systems, with key moti- vations among which the higher power generation and conversion efficiency, and ease of renewable integration. Compared to AC grids, the increased amount of converter devices in DC networks leads to higher a network capacitance owed to their filter components. Unlike AC systems, fault clearing in DC networks generally considers current flow interruption by a DC solid-state circuit breaker (SSCB) rather than by its mechanical counterpart. After such protective operation, the DC network is reconnected by the breaker device and large inrush current is provoked by the increased network capacitance, because it imitates a short circuit when being charged rapidly. Inrush current potentially causes undesired be- haviour or damage in network components or the SSCB itself, and must be avoided. This research proposes to use the solid-state power device of a SSCB in current saturation region in order to limit the inrush current, but without the use of additional current limiting elements. The proposal is addressed by development of a variable voltage gate driver to excite a silicon-carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) power device in current limiting mode, without exceeding its safe operation limits by conducting low continuous current or higher pulsed current, and while controlling its behavioural dependence on thermal and electrical conditions. Inrush current limiting performance of ten different power devices is compared to identify important characteristics of the power device itself, the proposed inrush current limiting method, and the power device control method. By assessment, the considered low voltage DC industrial network is estimated to contain 2.8mF network capacitance combined with negligibly low resistance and inductance. Network reconnection while limiting inrush current according to the developed soft-start procedure is experimentally achieved in 6.2s, satisfying the project objective to reconnect within 10s. This work showcases the availability of cost-effective methods for using SSCBs as apposite protection devices in low voltage DC networks.

The goal of this bachelor thesis is to reduce the voltage fluctuations in a dynamic inductive power transfer (DIPT) system, by determining the optimal coil location and/or spacing. In a segmented DIPT system the output voltage changes as the receiver (Rx) side moves over the transmit (Tx) side. By analyzing the spacings between the Tx- and Rx-coils it is possible to influence the output voltage and its fluctuations. The system studied consists of two rectangular Rx-coils in series, and multiple bipolar Tx-coils.

This research starts by building a model in COMSOL with one Tx- and one Rx-coil. Then a MATLAB program is presented which can simulate the whole system by, among others, phase shifting the original COMSOL data. Finally, the optimal coil location can be determined by comparing the average output voltage and the fluctuation in output voltage for different Tx- and Rx-coil spacings. Different tests are performed to confirm the results of the COMSOL model and the MATLAB simulations. The research showed that this system can not effectively reduce the voltage fluctuations, therefore a parallel configuration of Rx-coils is proposed. Simulation results show that this alternative solution can reduce the voltage fluctuations.

The growing complexity of electric vehicles asks for new battery management system (BMS) designs that are simpler, more reliable, and cost-efficient. This thesis presents the development of compact cell monitoring units (CMUs) that are mounted directly onto battery modules, eliminating bulky harnesses, reducing wiring complexity, and maintaining measurement accuracy. The CMUs combine redundant voltage and temperature sensing, passive balancing, and galvanic isolation in a custom four-layer printed circuit board optimized for thermal management and validated through simulation and experiments. Since these CMUs will be integrated into a future electrical/electronic architecture where the BMS master functions reside in the vehicle control unit, this design reduces component count and wiring complexity while maintaining functional safety. In parallel, a model-based state-of-charge (SoC) estimator was implemented as a redundant method to conventional Coulomb counting (CC), which suffers from drift, initial offset, and dependence on usable capacity. Through estimating the open-circuit voltage (OCV) during dynamic driving conditions with Kalman and H-infinity filters, a redundant SoC estimation method is demonstrated that compensates for the known drawbacks of CC. To prove the concept under realistic conditions, the model was validated not only on laboratory drive cycles but also on a real-life drive cycle containing measurement noise. Together, these innovations provide a cost-effective and scalable pathway towards robust battery monitoring and reliable SoC estimation in future electric vehicles.

In this thesis the lifetime assessment of low-pressure oil-filled (LPOF) cables is investigated. Most of the LPOF cables are already quite old but it is unknown if the degradation of these cables matches the age of the cable. Due to energy transition and the fact that not all cables can be replaced simultaneously, an estimate of the lifetime of the cable needs to be defined. This is done in this research using the following three research questions:
• What is the health level of the LPOF cables based on their historical loading profiles and their health index?
• Which LPOF cables are suitable for more loading?
• What is the remaining lifetime of cables that are suitable for more loading on this new loading levels?

These questions are answered using a thermal ageing model based on the historical loading data. From this model it could be concluded that the thermal degradation of the insulation of TenneT’s LPOF cables has been very limited even after 50 years of service. This means that it might be possible cable insulation wise to let it be run continuously on the nominal loading level (maximum allowed temperature) for another 47 years. Although it must be mentioned that the accessories remaining lifetime and loading capabilities are not investigated in this research.

There are done tan delta measurements on an old cable to see if there would be any degradation visible from the 50 years of ageing of the cable. From this testing there was no noticeable degradation in the insulation paper visible. However, from this testing it could not be fully conclude that no ageing would be visible from this cable. Therefore, more testing needs to be done which could be done in the following way.

The transition to renewable energy sources is essential to mitigate the impacts of climate change, with solar energy playing a pivotal role in this shift. Photovoltaic (PV) technology. However, the traditional single-junction cells are reaching their theoretical efficiency, which currently stands at 29.43%. Through the use of tandem solar cells, this efficiency limit can be surpassed. The tandem cell is being researched further to increase the power conversion efficiency (PCE). However, the conventional two-terminal (2T) and four-terminal (4T) tandem configurations face challenges related to current matching and optical losses, respectively.
This project addresses these challenges by focusing on the development and optimization of a three-terminal (3T) perovskite/silicon tandem module. The research aims to enhance the energy yield of 3T module under real-world conditions by developing a comprehensive 3T model within the Photovoltaic Material and Devices (PVMD) Toolbox, bridging the gap between cell-level and module-level optimization, which has been underexplored in existing studies.
The first step involved the development of the 3T model, which incorporates independent connections for each sub-cell and utilizes an interdigitated back contact (IBC) on the bottom cell as the third terminal. The 3T model is developed and simulated in MATLAB to be validated, showing close alignment of IV curves compared to the existing literature. The 3T model is then used to simulate a 72-cell module to be validated with a widely used electrical simulator called LTspice. The validation of the developed MATLAB 3T model against LTSpice simulations demonstrated a close match, with an RMSE result of 0.02% errors, confirming the model's accuracy in predicting the IV curves and energy yield for various operating conditions.
The second phase of the research involved detailed comparisons between the performances of 2T and 3T modules, each consisting of 72 cells, under both standard test conditions (STC) and real-world conditions in Delft as a sample. The simulations revealed that the 3T module provides less annual energy yield than 2T. However, the 3T module performs better than 2T at handling spectral irradiance variations and current mismatch situations under real-world conditions. At a certain hour, 3T outperforms 2T by yielding 220.75 W compared to 219.1 W. The loss analysis confirms that the 3T module produces less mismatch loss under real conditions than the 2T module. The simulations at four different locations also show that 3T has a certain number of times when 3T yields more energy than 2T. This shows the potential of 3T to outperform 2T by optimizing the perovskite bandgap energy and thickness.
The optimization of the 3T module focused on adjusting the perovskite layer's bandgap energy and thickness. The optimal bandgap energy is identified as 1.64 eV, and the ideal thickness is 600 nm for 2T, yielding 588.79 kWh. On the other hand, 3T has optimal perovskite bandgap energy and thickness of 1.82 eV and 600 nm, respectively, yielding lower energy of 583.24 kWh. Then, the modules are expanded into 144-cell modules, which results in 3T consistently yielding around 0.4% to 0.8% more energy at its optimum perovskite bandgap energy and thickness at 4 location samples compared to the 2T. For example, at Delft, the 3T yields more annual energy of 1172 kWh than 2T of 1167 kWh. This is due to the reduced end loss produced by 3T at a larger number of cells in the module. These results show that the 3T outperforms 2T at its respective optimum perovskite bandgap energy and thickness at every location sample and at a larger number of cell modules. Although the current 3T technology with IBC is still expensive, it is expected to become competitively priced in the future. These findings highlight the importance of ongoing optimization and development of 3T modules to fully unlock their potential in various environmental conditions.