Kornel Wolski, PhD, honoured in the ABB competition
Kornel Wolski, PhD
Kornel Wolski, PhD, from the Institute of Control and Industrial Electronics at Warsaw University of Technology’s Faculty of Electrical Engineering (WUT), has received a distinction in the ABB award competition for his doctoral dissertation. The competition, now in its 21st year, recognises outstanding BSc, MSc, and PhD theses aligned with the research scope of the ABB Centre.
Kornel Wolski, PhD, received a distinction and a financial prize of PLN 15,000. His doctoral thesis, titled “Single-Phase Quasi-Z-Source Inverter with Active Energy Buffer”, completed under the supervision of Professor Jacek Rabkowski.
– This research addresses a recognized market need for higher power densities in photovoltaic inverters, which could significantly reduce installation and logistics costs in mass production – explains Wolski, PhD. – Our method – based on efficient discretisation of the multidimensional design space—represents a major step toward fully automating the design of power electronic devices.
The dissertation addresses active energy buffers (AEB) for single-phase quasi-Z-source inverters (qZSI). The author first analysed the state-of-the-art in single-phase inverters with voltage boost/buck functionality and evaluated current decoupling solutions for second harmonic mitigation. After identifying gaps in existing analytical models, he proposed a generalised design framework for single-phase qZSI, featuring an extended mathematical model and an automated algorithm for identifying optimal component configurations.
The author formulated an original low-frequency discontinuous conduction mode (LF-DCM) theory, explaining current distortions in specific operating ranges applicable to any single-phase inverter topology with diodes. His design methodology was adapted to integrate an AEB at the qZSI’s main capacitor, maximising achievable solution space. This yielded an innovative converter topology with unique functionality, validated through simulation studies that compared its solution space against alternative topologies.
Simulations confirmed that the optimal configuration combines a voltage-buck-type energy buffer on the qZSI’s main capacitor with unipolar modulation. Wolski, PhD, subsequently synthesized high-frequency control/measurement algorithms using discrete-time stability theory, then designed, built, and laboratory-tested a prototype. The results validate both the design method (based on solution spaces) and the limitations predicted by his analytical model.