| Title |
Output Voltage Control of Duty Controlled 3-Level LLC Converter using Feed-forward Compensation |
| Authors |
Chan-Ho Kim ; Hyeong-Jin Lee ; Hag-Wone Kim ; Kwan-Yuhl Cho ; Sang-Min Lee ; Seung-Woo Baek |
| DOI |
https://doi.org/10.6113/TKPE.2024.29.3.224 |
| Keywords |
3-Level LLC resonant converter; Wide input voltage range; Feed-forward compensation; Hybrid(PFM;PWM) controller |
| Abstract |
The auxiliary power supply unit for railway vehicles provides a substantial amount of power to passenger cars. Generally, maintaining isolation from the catenary power line to the auxiliary power in the compartment is crucial. To achieve electrical isolation, a highly efficient LLC resonant converter is employed among isolated DC-DC converters. Generally, resonant converters primarily utilize PFM control methods. However, increasing the switching frequency at high input voltages is limited, causing a challenge in handling wide input voltage fluctuations from the overhead catenary power line. To address this limitation, the PWM control method is introduced alongside the existing PFM control method, resulting in the presence of two controllers. However, as these two controllers regulate the output voltage differently, output voltage overshoot is possible due to considerable input voltage fluctuations. This paper proposes a method that combines PFM and PWM controllers, along with feed-forward compensation, to address these shortcomings. The effectiveness of the proposed method is validated through PSIM simulation and experimentation. |