VFC-FFC Hybrid Control For Full-bridge LCC Resonant Converters Based on Single-Carrier Modulation

The traditional variable-frequency control (VFC) and fixed-frequency control (FFC) of LCC resonant converters have problems such as wide switching frequency variation and narrow ZVS range. Therefore, this paper proposes a single-carrier hybrid control for a full-bridge LCC resonant converter. At the same time of varying frequency, the phase- shift angle for LCC resonant converters is adjusted so that the circuit can achieve soft-switching operation in a slight variation of switching frequency. The control method can reduce the reactive power of LCC resonant converters and improve the utilization of magnetic elements. Finally, the simulation results show that when the input voltage is 100V-200V, the output voltage is 48V, and the output power is 100W-500W, the hybrid control reduces the switching frequency range by 42.3% compared with VFC and has a border range of soft switching than FFC.