1. Background and goal

The presence of power electronics converters in medium-voltage (MV) and high-voltage (HV) power grids has been increasing and is expected to become predominant in the coming years due to the growing penetration of high-power renewable energy sources and electrified loads. Considering that available semiconductor devices have limited blocking voltage capabilities, modular multilevel converter (MMC) topologies are typically employed in MV and HV grid-connected converter applications. Thereby, the power supply design of the gate-driving units controlling the active semiconductor devices is not trivial. For instance, the differential control voltage applied to the switches is generally between -5V and 20V. However, the reference control voltage, i.e., the source terminal for MOSFETs and the emitter terminal for IGBTs, might be at a high voltage potential. The power supply of gate-driving units in MV and HV converters can consist of self-powering circuits. For example, the energy stored in the capacitor of each sub-module is harvested and used to power the gate-driving units. However, this implies that it is not possible to control and monitor the state of the semiconductor devices when the converter is not operating. On the other hand, using external low-voltage auxiliary power supplies referenced to the ground potential provides full controllability on the power switches. Nevertheless, this means that the isolation of these auxiliary gate-driving power supplies requires special consideration, especially for DC-link voltage levels above 10kV.
The PhD candidate will research optimum isolated power supply architectures based on inductive power transfer (IPT) for gate-driving units used in MV-MMC converters. Galvanic isolation based on IPT takes advantage of the large air gap achievable between the coupled coils, which is required due to the high potential difference.

2. Research challenges

This project consists of the investigation of two main parts: circuit topologies, and IPT coil configurations.
In this application, the main goals are realizing auxiliary power supplies with a small form factor to ease the integration with the power sub-modules and low coupling capacitance between the IPT coils to minimize electromagnetic interference. Specifically, we foresee the following research contributions.

• Benchmark of different circuit architectures for the gate-driving isolated power supplies. The evaluation metrics are the power transfer efficiency, the capability of fault tolerance, and modularity to ease the integration into the MMC, reparability, and maintenance.
• Multi-objective optimization of the IPT coils. A strongly physics-informed approach combined with machine learning/AI methodologies is used for the coil designs, considering different geometries, materials, and structures.
• Experimental verification of the analytical models and simulation results.
• Generalization of the found solutions to other converter topologies used in MV and HV applications.

3. Role

PhD student.

4. Work environment

Eindhoven University of Technology (TU/e) is a young university, founded in 1956 by industry, local government, and academia. Today, their spirit of collaboration is still at the heart of the university community. We foster an open culture where everyone feels free to exchange ideas and take initiatives.
Eindhoven University of Technology offers academic education that is driven by fundamental and applied research. Our educational philosophy is based on personal attention and room for individual ambitions and talents. Our research meets the highest international standards of quality. We push the limits of science, which puts us at the forefront of rapidly emerging areas of research. Eindhoven University of Technology combines scientific curiosity with a hands-on mentality. Fundamental knowledge enables us to design solutions for the highly complex problems of today and tomorrow. We understand things by making them and we make things by understanding them.
Our campus is in the centre of one of the most powerful technology hubs in the world: Brainport Eindhoven. Globally, we stand out when it comes to collaborating with advanced industries. Together with other institutions, we form a thriving ecosystem with one common aim - to improve quality of life through sustainable innovations.
The Electromechanics and Power Electronics group is one of the nine research groups of the Department of Electrical Engineering at TU/e. The group is the main center for research in electromechanical power conversion and power electronics in the Netherlands. The research is aligned with the three main strategic research themes of the Eindhoven University of Technology, i.e. Energy, Health and Smart Mobility. The four research tracks of the EPE group are high-tech motion systems and robotics, power electronics systems, smart mobility and advanced modeling. Furthermore, the group is one of the founders of the High Tech Systems Center in which all mechatronic knowledge of the TU/e will be bundled.

We are looking for candidates matching the following profile:

• MSc degree in Electrical and/or Power Engineering.
• A very strong analytical background, with solid mathematical and multi-physics knowledge.
• Excellent problem-solving abilities for power electronics and electromechanics systems with demonstrated hands-on experience.
• Ability to independently organize your own work, to solve problems, to cooperate, and to achieve desirable goals.
• Strong curiosity for scientific challenges and creativity in solving practical problems.
• Ability to participate in the teaching process in BSc and MSc programs (both taught in English),
• •Strong command of the English language.
• Excellent scientific writing skills, preferably proven with peer-reviewed publications.

A meaningful job in a dynamic and ambitious university, in an interdisciplinary setting and within an international network. You will work on a beautiful, green campus within walking distance of the central train station. In addition, we offer you:

• Full-time employment for four years, with an intermediate evaluation (go/no-go) after nine months. You will spend 10% of your employment on teaching tasks.
• Salary and benefits (such as a pension scheme, paid pregnancy and maternity leave, partially paid parental leave) in accordance with the Collective Labour Agreement for Dutch Universities, scale P (min. €2,872 max. €3,670).
• A year-end bonus of 8.3% and annual vacation pay of 8%.
• High-quality training programs and other support to grow into a self-aware, autonomous scientific researcher. At TU/e we challenge you to take charge of your own learning process.
• An excellent technical infrastructure, on-campus children's day care and sports facilities.
• An allowance for commuting, working from home and internet costs.
• A Staff Immigration Team and a tax compensation scheme (the 30% facility) for international candidates.