POWER SUPPLY SYSTEM FOR VEHICLE

A power supply system for a vehicle is provided, and the system may include: a charging inlet connected to a main battery and connectable to a power supply external to the vehicle; a voltage converter configured to step down a power of the main battery by a switching element and supply the stepped-down power to a sub-battery; and a controller configured to control the voltage converter, in which the controller is configured to slow down a switching speed of the switching element, as compared with when the main battery is not being charged, while the charging inlet is connected to the power supply and the main battery is being charged by the power supply.