Design of LLC converter based on BUCK series wide range voltage regulation

LLC resonant converter has good switching characteristics and can improve the power density, which is widely used in photovoltaic power generation, electric vehicles and other fields. However, many applications require LLC resonant converters to operate over a wide voltage gain range. Therefore, the researchers proposed that the LLC resonant converter adopt variable frequency control or phase shift control, but it is difficult to take into account both wide voltage gain and high efficiency. Therefore, this paper proposed a wide-range BUCK series regulated LLC converter, where the output voltage is formed by the series superposition of two output capacitors, and the control adopts two separate PI compensators for closed-loop control. In order to verify the feasibility of the scheme, this paper builds a simulation model and conducts experiments. The experiments show that the topology of the scheme can output a wide voltage range, and LLC can work in the soft switching state and the control loop is stable. The scheme proposed in this paper has theoretical feasibility.