PhD defence by Zhengge Chen on Topology Derivation and Mission Profile Based Modeling of Bridgeless PFC Converters
19.02.2021 kl. 13.00 - 16.00
Zhengge Chen, Department of Energy Technology, will defend the thesis "Topology Derivation and Mission Profile Based Modeling of Bridgeless PFC Converters"
Topology Derivation and Mission Profile Based Modeling of Bridgeless PFC Converters
Professor Huai Wang
Associate Professor Pooya Davari
Associate Professor Tamas Kerekes
Associate Professor Tamas Kerekes, Dept. of Energy Technology, Aalborg University (Chairman)
Professor Jorma Kyyrä, Aalto University
Roberto Alves Baraciarte, HITACHI ABB Power Grids Sweden AB
Active power factor correction (PFC) converters are typically used as the front-end in the power electronic equipment to avoid the distorted AC input current, which may cause noises, overheat, component malfunctions, etc. The commonly used single-phase PFC converter consists of a diode bridge and a DC-DC converter cell. However, there are always two conducting diodes in the diode bridge that results in considerable conduction losses. Therefore, in order to minimize the conduction losses, PFC converters without the diode bridges, namely the bridgeless PFC converters, are gaining popularity in recent decades.
Numerous bridgeless PFC topologies with different configurations targeting on various power levels and applications are proposed to replace their conventional topology counterparts. However, only several references cover the topic that why this bridgeless configuration can work and how bridgeless topologies can be derived. Thus, the first contribution of this thesis is to demonstrate the bridgeless topology derivation methods, which essentially arranges two converter cells in the input-parallel output-parallel (IPOP) and input-parallel output-series (IPOS) to obtain the topologies. This approach not only enables the systematical derivations of the dual-converter cell-based bridgeless topologies, but also offer the bridgeless topology categories according to the IPOP and IPOS cell configurations. Moreover, four possible research aspects are given among this topology topic. As an example, the dualcell bridgeless topology simplification guidelines are presented to derive the same converter cell-based bridgeless family and explain why some of the family members have simpler structures. Besides, by comparing the topologies, the converter performance differences between the simplified bridgeless topologies and their original IPOP and IPOS topologies are summarized.
On the other hand, given that various bridgeless topologies are available, the second major goal of this thesis is to conduct a comparative study based on modeling and a consistent design procedure. Moreover, for the sake of simplicity and consistency, components from the same product series are considered in the database. Besides, this design procedure selects the key components according to the calculated junction/hot-spot temperatures or the winding factor for the inductor cores, which are derived by the iteration loop based on the built component models. The obtained topology benchmarking results are in terms of volume, cost, and power loss. Case study 1 demonstrates how to build this design procedure step by step and case study 2 shows how to use the benchmarking results with a specific mission profile to estimate the bridgeless topology material cost payback period compared with the conventional topology.
Moreover, based on the benchmarking results in case study 2, the IPOS boost topology with high efficiency and the unique DC split output structure is chosen for further study, along with the conventional boost topology. Combining the base transceiver station (BTS) load mission profile, a simplified mixed conduction mode (SMCM) control for the IPOS boost topology is proposed to mainly improve the power factor (PF) and input current total harmonic distortion (THDi) in the light loads. Furthermore, the power loss model results also show the slightly increased efficiency in light loads. The control effectiveness and the improved performance are verified by the experiment test. Furthermore, given the typical BTS mission profiles in a rural area, the state-of-the-art mission profile-based reliability analysis method is employed. Then, the accumulated failure of the IPOS boost PFC converter under the average current (AVC) control and the SMCM control, along with the conventional boost PFC converter under the AVC control are estimated. The analysis results indicate that given 20 years of operation, the SMCM controlled IPOS boost PFC converter has the accumulated failure 0.24 %, mildly lower than the AVC controlled IPOS boost PFC converter (0.27%) and considerably lower than the AVC controlled conventional boost PFC converter (2.06%). Hence, the SMCM controlled IPOS boost PFC converter is a promising candidate for telecom BTS in the rural area.
The research outcomes are verified by simulations and experiments. The contributions have been summarized in three journal papers and three conference papers.
THE DEFENCE IN ENGLISH - all are welcome.
Department of Energy Technology