Electric system for fuel cell, fuel cell vehicle, and method of supplying electric power

An electric system for a fuel cell, comprising:

• a fuel cell for generating electric power by being supplied with a reactive gas;
• a first electric storage device having a voltage lower than a voltage output from said fuel cell;
• a first power supply line connected to said fuel cell;
• a second power supply line connected to said first electric storage device;
• a first DC-to-DC converter for performing bidirectional voltage conversion between said first power supply line and said second power supply line;
• a main unit and a first electric accessory for being supplied with electric power from said first power supply line;
• and
• a second electric accessory for being supplied with electric power from said second power supply line.

A method of supplying electric power, comprising the steps of:

• supplying a main unit and a first electric accessory with electric power through a first power supply line from a fuel cell which generates electric power by being supplied with a reactive gas;
• supplying a second electric accessory with electric power through a second power supply line from an electric storage device having a voltage lower than a voltage output from said fuel cell;
• supplying electric power having a voltage lowered from a voltage on said first power supply line by a DC-to-DC converter capable of performing bidirectional voltage conversion, through said second power supply line to said second electric accessory or to said electric storage device to charge the electric storage device;
• and
• supplying electric power having a voltage increased from a voltage on said second power supply line by said DC-to-DC converter, through said first power supply line to said main unit or said first electric accessory.