| Abstract |
Highly reliable LLC resonant converters operating even under fault conditions are important in aerospace, data center, and electrolyzer applications that require continuous and stable power supply. Therefore, analyzing the operating characteristics and researching methods for maintaining output voltage is essential. Thus, this paper analyzes the operation mode and resonant characteristics of a three-phase delta-delta LLC resonant converter after faults, focusing on open-circuit faults. Based on the analysis, equivalent circuits and voltage gain curves after the faults are derived and compared with those before the faults. The decreased output voltage due to the faults are recovered through PFM(Pulse Frequency Modulation). Consequently, the output voltage is recovered without additional components, and it is intuitively interpreted that the operating frequency is adjusted to achieve voltage gain as the resonant frequency changes after the faults. The analysis results are verified by PLECS simulation. |
