The increasing global energy demand calls for attention on renewable energy development. Among the available technology, the photovoltaic (PV) panels is a popular solution. Thus, targeted Power Conditioning Systems (PCSs) are drawing increased attention in research. Microconverter is one of the PCS that can support versatile applications in various power line architectures. This work focuses on the comparison of circuit secondary side architectures for LLC converter for microconverter application.
As the research foundation, general characteristic of solar energy and PV panel operation are introduced for the understanding of the needs. Previous works are referenced and compared for advantages and limitation. Base on conventional secondary resonant full bridge LLC converter, the two sub-topologies of different secondary rectification network: active, full bridge secondary and active voltage doubler output end LLC converter are presented in detail. The main operating principle is also described in mathematical formula with the corresponding cycle-by-cycle operation to ensure the functional equality before proceeding to performance comparison.
Circuit efficiency analysis is conducted on the main power stage and the key components with frequency consideration. The hardware circuit achieved the designed function while the overall hardware efficiency result agrees with analysis. In the implementation, the transformer is costume built for the system pacification. Another part is the parasitic effect analysis. At a high operating frequency and to achieve very high-frequency operation, parasitic effect need to be fully understood and considered as it may have the dominating effect on the system. / Master of Science / With the increasing demand for electric energy in today's world while the traditional natural energy recourses such as coals running towards depletion, renewable energy sources become an important alternative. Among them, solar energy is an option with easy access and convenient utilization. The photovoltaic (PV) panel requires matching Power Conditioning Systems (PCS) for connection and adaptation. Microconverter is one of the PCS that can support versatile applications in various power line architectures. This work focuses on different sub-circuitry for PV application under LLC converter category, which is a popular and effective solution for renewable energy dc-dc power conversion.
First, the research background is studied, which lays the ground for the utilization of LLC converter for PV application. Then the topology under study is presented in detail. In this work, the foundation of variation is based on secondary resonant full bridge LLC converter. For verification of functionality, the step-by-step operational breakdown are listed for the two verification proposed of different secondary topology. The efficiency analysis and performance verification are conducted on the given circuitry. Then the analog testing board is built and tested while the result agrees with the analysis.
A few additional topics regarding detail of the system is discussed at more length. One is the magnetic component design, which is the key part for stable and efficient system operation; another is the parasitic effect, as at such high frequency and efficiency range, the parasitic effect become significant for the circuit performance.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/82490 |
| Date | 13 March 2018 |
| Creators | Yan, Jinghui |
| Contributors | Electrical Engineering, Lai, Jih-Sheng, Ha, Dong S., Li, Qiang |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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