BIDIRECTIONAL POWERING ON-BOARD CHARGER, VEHICLE POWER SUPPLY SYSEM INCLUDING THE SAME, AND CONTROL METHOD THEREOF

A vehicle power supply system is provided. The system includes a main battery and an OBC having first and second input/output terminals, in which AC power input to the first input/output terminal is converted into DC power to be output to the second input/output terminal, and a magnitude of the DC power input to the second input/output terminal is converted and output to the first input/output terminal Additionally, the system includes an LDC in which a DC voltage input from the main battery is converted into a low voltage to be supplied to an auxiliary battery or an electronic load and a switching unit is connected between the first input/output terminal and the LDC. A controller is then configured to adjust a powering direction of the OBC and an on/off state of the switching unit, based on whether the main battery is charged and whether the LDC fails.