A Novel Five-level LLC Resonant Converter and Its Modulation Strategy

For the DC-DC link following the on-board charger of electric vehicles, as well as in applications such as electric vehicle charging, rail transit power supply systems, and medical equipment power supplies, this paper proposes a novel five-level LLC resonant converter based on switched capacitors. This converter achieves a five-level output through a switched capacitor circuit, offering a simple structure and high efficiency. Research indicates that employing LLC resonant technology effectively reduces switching losses and enhances system efficiency. Additionally, the integration of the switched capacitor circuit allows for a wide-ranging output voltage adjustment, accommodating the charging needs of various battery types. To further improve performance, the converter employs level-shifted sinusoidal PWM (LS-PWM) modulation, which optimizes switching operations and minimizes harmonic distortion. In order to verify the accuracy of the proposed resonant converter, a converter with a switching frequency of 100 KHz and an input of 220 V was built in the PSIM simulation for validation.