POWER SUPPLY SYSTEM FOR VEHICLE, AND CONTROL METHOD OF POWER SUPPLY SYSTEM

A power supply system for a vehicle includes: a main power supply; an electric power converter including a capacitor; a relay; a sub power supply; a boost converter; a cooler; and a controller configured to cause the sub power supply and the boost converter to precharge the capacitor, when a main switch of the vehicle is turned on and before the relay is closed to connect the electric power converter to the main power supply. The controller is configured to perform one of a control i) and a control ii) when one of a temperature of the boost converter and a temperature of a coolant in the cooler is higher than a specified temperature threshold. The control i) being a control to start the precharging while starting up the cooler. The control ii) being a control to start up the cooler before the precharging.