Three-phase LLC resonant converter with variable magnetizing inductance to extend gain range
Funding information: This research was supported by the Hebei Natural Science Foundation under grant E2023203148 and the Science Research Project of Hebei Education Department under grant ZD2021101.
Summary
LLC resonant converter has been widely employed in electric vehicle (EV) charging applications. Compared with single-phase LLC converters, three-phase LLC converters provide a smaller current ripple, higher power capacity, and higher power density at higher power levels. However, the conventional three-phase LLC converter, which adopts pulse frequency modulation (PFM), has the issue of limited gain range. In this paper, a three-phase LLC resonant converter with variable magnetizing inductance is proposed. A two-stage control strategy of PFM and fixed-frequency magnetizing inductance modulation (MIM) is proposed. The wide gain range needed for EV charging is realized by modulating magnetizing inductance and frequency. Finally, a 2.7 kW prototype with 400 V input and 280–420 V output range verifies the theoretical analysis and parameter design. The experimental results show that the converter can achieve soft switching and a wide gain range and the peak efficiency is 97.7%.
CONFLICT OF INTEREST STATEMENT
The authors declare no potential conflict of interests.
Open Research
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.
