PhD defence by Chao Liu

Partial power processing technologies have emerged as a solution to the growing demand for high efficiency and power density in power electronics. By only processing a portion of the total power and regulating the voltage difference between the input and load, partial power converters can achieve higher efficiency and power density than traditional full power converters. The configuration of connecting one terminal in parallel with the power source or load and another terminal in series with the power source and load is one of the key features that allow partial power converters to achieve these improved results.

Despite the partial power converter concept being proposed for some time, several key issues still need to be addressed. The use of power processed by the converter as a traditional evaluation metric is limited and does not provide a comprehensive picture of the performance of different topologies. Additionally, the role of the transformer in the partial power converter and the modulation strategies for step-up/step-down partial power converters are important factors that are often overlooked. These are key areas that need to be further researched and developed in order to fully realize the potential of partial power converters.

This thesis investigates the four aspects of the mechanism, topology, modulation strategy, and magnetic design to design a partial power converter for electrolytic cells with a peak efficiency of over 99%. Moreover, partial power processing is extended to the AC system. Therefore, an integrated energy conversion system for the electrolyser system is proposed, which meets the system power factor and efficiency requirements.