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Comparison of High-Power DC-DC Converters for Solar Applications with Respect to Efficiency and Chip-area

Babak Alikhanzadehalamdari
Göteborg : Chalmers tekniska högskola, 2018. 54 s.
[Examensarbete på avancerad nivå]

This thesis is intended to analyze and compare the efficiency of the conventional 2L-DAB with the so-called Multi-Level DAB (ML-DAB) and three-Level DAB (3LDAB) for the solar applications. The latter features from the three-level legs both on the LV and the MV sides; while, the former is a combination of the 2L-legs on the LV side bridge and the NPC legs on the MV side bridge. The converters are rated for 1MW power with the LVDC-link and the MVDC-link voltages of 1.3kV and 16kV respectively. The SiC MOSFETs are utilized as the power switches to ensure low switching losses in high switching frequencies. The semiconductor chip-area based comparison algorithm is applied to have a fair comparison between the topologies. The definition of average efficiency for the European solar mix is employed to make the comparison specific to the solar applications. The switching frequency of the converters is swept from 10kHz to 80kHz to investigate its effect on the performance of the converters. The chip-area of the MOSFETs are also varied to explore the efficiency variations with the chip-area change and therefore, the semiconductor costs. It has been shown that for the specified modulation parameters and the same operating junction temperature , the 2L-DAB has higher full-load efficiency while, it requires lower chip-area than the ML-DAB for all switching frequency ranges. It has also been demonstrated that for the same amount of investment on the semiconductors, the 2L-DAB can achieve a higher efficiency and a lower operating temperature for the MOSFETs compared to the ML-DAB. It was also shown that by less than 70% increase in the required chip-area, the full-load efficiency and the average efficiency for European solar mix of all converters can increase more than 2% and 0.7% respectively for all switching frequency ranges.

Nyckelord: SST, DC-DC converter, DAB, NPC, Efficiency, Chip area, PV

Publikationen registrerades 2018-04-09. Den ändrades senast 2018-04-09

CPL ID: 254948

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