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On-board and Off-board Charging Systems

D08.5 - Single-Stage On-Board Charger Based on LLC Converter with Output Ripple Suppression Control

Thursday, March 26, 2026
12:00 PM - 1:45 PM CT
Location: Hemisfair Ballroom
The power density and the reliability of the On-board charger (OBC) are significant for the electric vehicle powertrain. In the traditional two-stage OBC, the large electrolytic capacitor (E-Cap) of the DC bus increases the volume of the OBC, and the short life time of the E-Cap will also decrease the reliability. Thus, the single-stage OBC is proposed to discard the bulky E-Cap bank. However, low DC bus capacitance will increase the double-line output ripple. To suppress the ripple, a large output capacitance is still required. Thus, the volume of the DC filter capacitor cannot be reduced. To tackle this issue, the double-line output ripple suppression control method based on the back-end LLC converter is proposed in this paper. To optimize the efficiency simultaneously, the hybrid modulation, which contains inner phase shift modulation (PSM) and pulse frequency modulation (PFM), is proposed. The simulation results based on a 400V/1.65kW prototype reveal that the total DC filter capacitance can be reduced by 86%, and the ripple voltage can be decreased from 80Vpp to 4Vpp.