CONVERTER AND POWER CONVERSION SYSTEM FOR CONVERTING POWER OF AUXILIARY BATTERY USING OBC

In an embodiment, a power conversion system includes: an on-board charger; a main battery configured to be recharged with power and to supply the recharged power to a motor, thereby supplying rotation force to a wheel of a vehicle; an auxiliary battery configured to recharge the main battery or to assist a power supply function of the main battery; and a power converter connected to the auxiliary battery, the power converter comprising a bypass circuit and a buck switch. A part of the on-board charger and the power converter constitute a DC-DC converter, and the buck switch is configured to be repeatedly switched on and off when a voltage of the auxiliary battery is higher than a voltage of the main battery, and does not operate when the voltage of the auxiliary battery is not higher than the voltage of the main battery.