Fuel cell unit

A fuel cell unit comprising:

• a fuel cell stack;
• a boost converter including at least a switching element and a reactor adapted to boost electric power output from the fuel cell stack;
• a reactor cooling component including a channel for refrigerant for cooling the reactor;
• a switching element cooling component including a channel for refrigerant for cooling the switching element;
• a cooling pipe including a first cooling pipe through which refrigerant flowing out of the reactor cooling component and into the channel for refrigerant of the switching element cooling component flows, and a second cooling pipe through which the refrigerant flowing out of the channel for refrigerant flows;
• and
• a relay adapted to switch on and off the electric power output from the fuel cell stack, and
• a precharge circuit;
• wherein the fuel cell stack, the boost converter, the cooling pipe, and the relay are housed in one case, and the relay is disposed in a position closer to the cooling pipe than to the switching element;
• wherein the relay is disposed in a position between the first cooling pipe and the second cooling pipe;
• and
• wherein the cooling pipe is arranged such that coolant flows first through the reactor cooling component, then through the switching element, and then between the relay circuit and the precharge circuit.