In this thesis, the main objective is to argue and address the best fitting micro grid electric distribution system for a typical water-pump systems whereby the primary energy sources is renewable. So far, the grid whose main sources were wind, fossil fuel and solar energy has achieved the energy supply for the pump located at 51° 26’ 58” N and 4° 13’ 41” E. Seasonal changes were taken into consideration when carrying out the analyzes in the study from both perspectives; the load side and the energy sources. Energy efficiency is analyzed and compared across multiple types of micro grid distribution systems, and the raw data are processed by HOMER program and the results are deduced as such.
The study consists of various grid configurations. Each grid configuration (AC, DC and hybrid AC/DC) is also analyzed by assuming that all three main energy sources are connected to the micro grid. The system performance is also analyzed with 50% load increase in the AC-DC hybrid network. Besides, each grid configuration was re-analyzed using multiple types wind turbine and PV panels and the results were depicted. In Rilland-Netherlands, which was the selected pilot area, solar energy technologies are not utilized sufficiently because the solar energy potential is low. Therefore, most of the energy is supplied by wind power generation systems. For this region, energy surplus produced could be stored in batteries. However, this is not an option due to the cost and technical constraints. According to the analysis results obtained via the HOMER program, the most appropriate solution is to use a hybrid micro grid whose energy source is renewable and it is Grid-Connected. In this regard, the Grid/PV/wind renewable hybrid in a hybrid AC/DC micro-grid system is the most suitable one for the selected pilot area Rilland-Netherlands.

The transportation industry is causing 14% of the worldwide greenhouse gas emission. Therefore, the United Nation concluded with the Paris climate agreement to reduce and limit their emissions to keep the global average temperature increase below 2 degrees Celsius. Based on the agreement the European union introduced new regulations to limit the average fleet emission of car companies. In this push towards lowering emission the companies introduced their first generations of electric cars. To further improve the efficiency of the electric drive train new multilevel topologies were introduced. One of the topologies is called modular multilevel converter (MMC) introduced by R. Marquardt and A. Llesnicar in 2003. This new topology main advantage are its modularity and the option to use low voltage component. However, no company industrialized the MMC for drive train application. The reason therefore are the extensive control architecture, hardware and software wise. This thesis investigated possible ways to reduce the wiring and complexity by introducing a low level communication bus together with distributing the control to remove the centralized architecture. Therefore, the different possible low level communication bus were analysed and compared. The different bus protocols were compared based on speed and time to send the same amount of information to control a MMC. It was concluded that the serial peripheral interface bus (SPI) shows the highest capability for the proposed single phase 5 level converter set-up. Therefore, an experimental system was built to validate the performance. The system itself was designed with the goal to use low cost and low voltage component. The validation of the experimental set-up showed the stable operation of the system with an open loop control. Thereby it proofs the possibility to integrate and control the MMC with a low level communication bus. The results can be used as a baseline to further research on integrating theMMC and make it viable for drive train applications.

Inductive power transfer (IPT) has become a hot topic and is supposed to have a wide range of application in the future. This thesis focuses on the IPT system with multiple pickups in the lighting application. A multiple pickup system can power more than one pickup at the same time and the power consumption varies with a different number of pickups connecting in the circuit. A problem with the multiple pickup system is that at light load the power supply consumes a large amount of reactive power for a small active power demand. The aim of the design is to build a power supply with a constant current output. The designed circuit is supposed to reduce the reactive power demand and keep zero voltage switching (ZVS) in all range of load.

This thesis selects the half bridge inverter and LCL-T network as the topology. The characteristic of the LCL-T network is first analyzed under first harmonic approximation. The trade off between the constant current output, reactive power demand, and ZVS is interpreted. The system is proposed to work at a higher frequency for a light load. In addition, the effects of higher order harmonics on the switching current and apparent power are also given in the form of calculations. Subsequently, the parameters in the topology of the half bridge inverter and LCL-T network are determined. The control circuit is built to realize automatic frequency switching according to the load condition. The next step is to simulate the designed circuit in LTspice and construct it in the lab. The result of simulation and experiment verifies that the reactive power demand is reduced with a higher frequency at light load. Constant current output and ZVS are ensured at the same time in all range of load. But the efficiency of the system does not show a clear improvement since the loss is dominated by the cable loss, which is determined by the requirement of cable current and the pickup design.

A driver with high power factor, high efficiency and safety isolation are more attractive in the lighting application. Flyback is an ideal choice to be the power factor stage in LED driver. But one of the most difficulty in flyback topology is the energy stored in its leakage inductance. This part of the energy will introduce very high voltage spike on the main switch. A clamp circuit is needed.Passive clamp flyback converter is with few components and effectively clamping the voltage stress on transistor. But its switching frequency is limited by its switching loss. So the transformer volume in passive clamp flyback is very bulky. The aim of this project is to investigate high switching frequency Active Clamp Flyback converter with GaN transistor as power factor correction in lighting application.With the active clamp loop, the leakage inductance energy and snubber loss could be utilized properly to allow ZVS on switches under all line and load conditions and recycled to input source.So high switching frequency and high efficiency are both achievable.
In this project,specific control method, dead time length and conduction mode are properly designed for active clamp flyback converter as PFC in lighting application.The implementation of closed control loop is not included.A 50W (75V) prototype of active clamp flyback front end converter operation around 1MHz with GaN transistor as Power Factor Correction stage in lighting application is developed to verify the analysis.

In a cordless kitchen system, the appliances do not make use of a power cord. The system consists of a power channel and a communication channel. There are various resonant topologies which can be implemented in the power channel[9]. The chosen topology should meet the functional as well as non-functional equirements of the system. Presently, a series resonant topology is used in the system. The topology is easy to understand, to implement and could meet the functional requirements like the amount of power and high efficiency of the system easily. But, it is difficult to meet the non-functional requirements like overvoltage protection, EMI and simple control of the system. This master’s thesis is mainly focused on design and realization an inductive power transmitter which addresses the following research questions:
• EMI: The present inductive power transmitter is based on a series resonant inverter which has a disadvantage of high dV/dt’s across the inverter bridge and the transmitter coil. Furthermore, ZVS of the power switches can be lost at low duty cycles or low loads. Both mechanisms causes high dV/dt’s in the system, which results in increase in common mode noise problems.
• Overvoltage: The present series resonant topology with the calculated circuit components and given load conditions (coupling factor (k) and load resistance (RL)), is observed to be operating in the capacitive mode of operation, when the load is disconnected/removed. Therefore, disconnection of the load causes overvoltage on the transmitter as well as the receiver coil. The overvoltage, in the absence of ’expensive’ protective means, can damage the system components and the system may fail to operate.
• Simple control: The present system is a 4th order system. Due to weak coupling between the transmitter and the receiver coils, there exists multiple operating points where the voltage gain is the same. Therefore, it is difficult to find an optimal operating point for the control loop. Also, as mentioned in previous point, the load disconnection results in capacitive mode of operation of the system. To protect the system the control loop should take care that the system operates in the desired inductive mode of operation, as fast as possible and without causing significant losses.
The report proceeds with an introduction about the cordless kitchen project. It is followed by the description and the analysis of the present system. Next, the detailed analysis of other possible topologies and selection of the alternative topology is described. It is followed by the description about the new proposed model. The report concludes with the conclusion and a paper publication. The paper is published during the Wireless Power Congress arranged by WEKA FACHMEDIEN GmbH in July-2017.

In recent years, superconducting synchronous generators (SCSGs) have been proposed as an alternative to permanent magnet synchronous generators (PMSGs). They are expected to reduce the top head mass and the nacelle size for such large wind turbines. In 2012, the INNWIND.EU project initiated this research to investigate SCSGs for 10-20MWdirect-drive offshore wind turbines. However, the feasibility of SCSGs was limited by a few critical issues, such as high costs, AC losses in the superconducting winding and excessive short circuit torque. Furthermore, SCSG designs proposed in the literature were various but all less competitive than PMSGs.@en