Photovoltaic (PV) modules yield considerable lower energy in the field than what is expected from their rated power, indicated as “Watt-peak (Wp)”. The latter is measured under “standard test conditions” but in climates like Western Europe, these are rarely met. In fact, the main energy yield losses (kWh/kWp) in these climates, can be attributed to a reduced illumination resulting in lower current, and non-uniform illumination conditions (shading, clouds, soiling, ...) leading to current mismatch in the serially connected cells inside the module.
In order to maximize the power production of PV modules working under non-uniform illumination conditions, we are building advanced “smart” PV modules able to dynamically establish different non-series topologies. These modules are organized in small groups of cells (cell-strings) that can be connected each other either in series or in parallel by means of reconfiguration switches. Intra-module (local) converters are used to ensure suitable current and voltage level and allow a direct control of the operating point of the cell-string. Design and realization of such reconfigurable modules pushes beyond the current state-of-the-art. First of all, novel DC/DC converters are needed. The circuit design is challenging, since high current levels are expected due to parallel connection of cell-strings whereas a strong minimization of cost together with acceptable losses and efficiency are required. That is not achieved by commercial module- and submodule-level power converters, which are normally rated for lower current levels, namely the current of a single cell, and come with significantly higher costs. Solving this challenge will pave the way for the realization of innovative building integrated PV systems, showing a significantly higher energy yield while maintaining reasonable costs. The same applies to solar powered vehicles, where non-uniformity among PV elements is usual. Also, the field of application is not limited to photovoltaic systems. For instance, such converters may be used to implement cost-effective reconfigurable battery systems.
The goal of this Ph.D. project is to design such novel DC/DC converters, to be used as local converters for reconfigurable PV modules. Both PCB-level and fully integrated solution will be explored. Also, both conventional silicon devices and wide bandgap semiconductors, such as GaN and SiC, will be considered. The candidate will join imec’s PV module team and will work closely with control algorithm design experts, who will be responsible for developing the PV module reconfiguration algorithm. The candidate jointly with imec’s technology team and its prototyping capabilities will realize also a first demonstrator of its convertor design and validate it in the lab.
Required background: electrical engineer with a strong background in the domain of power electronics, preferably applied to photovoltaic sources. Previous hands-on experience with electrical measurements and converter characterization is desirable.
Type of work: 70% DC/DC converter design, 10% system design, 20% measurements and validation
Location: This position will be at the site of EnergyVille where you will have direct access to outdoor measurement sites, and experts working on power electronics, grid load management and various topic related to smart grid development. You could work in imec’s and KULeuven state-of-art labs.
Supervisors: Francky Catthoor and Jef Poortmans
Daily advisor: Patrizio Manganiello
The reference code for this PhD position is SE1804-02. Mention this reference code on your application form.