The LLC half bridge system uses 2 switching elements and 2 secondary side rectifying elements, making it powwibl to configure a compact and highly efficient power supply.
Since transformer current can be used by flowing in both positive and negative direction, it is possible to miniaturize the transformer, and the ripple current of the input/output capacitor is also small, so the capacitor can be miniaturized.
It is usually used for power supply of medium capacity or more using PFC.

By configuring the secondary side diode as a bridge configuration, it is possible to make 1 secondary winding.
There are 2 but the withstand voltage of the diode is half.