Heating control method for fuel cell vehicle

A heating control method for a fuel cell vehicle which comprises a coolant line for cooling a fuel cell stack, an electric heater for heating air supplied to the interior of the vehicle, a coolant pump that pumps and transports coolant to circulate through the coolant line, a cathode oxygen depletion (COD) provided at a downstream side of the coolant pump in the coolant line, a bypass line branched from the coolant line between a upstream side of the coolant pump and a downstream side of the COD, and a heater core additionally provided in the bypass line at downstream sides of the coolant pump and the COD and provided together with the electric heater for heating air supplied to the interior of the vehicle by heat exchange with the coolant discharged from the fuel cell stack, the method comprising:

• (a) detecting a state of charge (SOC) of a battery when an interior temperature of the vehicle is lower than a predetermined temperature set by a driver;
• (b) when the SOC of the battery is above the predetermined lower limit, heating the interior of the vehicle by operating the electric heater by power of the battery;
• (c) when the SOC of the battery is below the predetermined lower limit, heating the interior of the vehicle by operating the electric heater by power generated by the fuel cell stack and when a temperature of the coolant is above a predetermined temperature at which the fuel cell stack does not reach a normal operating temperature, heating the interior of the vehicle using both the heater core and the electric heater;
• and
• (d) when the temperature of the coolant is increased above a normal operating temperature of the fuel cell stack, heating the interior of the vehicle using only the heater core while turning off the electric heater,
• wherein when the fuel cell stack is in an idle stop mode in step (b), operation of the fuel cell stack is initiated by supplying reactant gases to the fuel cell stack,
• wherein the temperature of the coolant is increased by operating the COD, the COD heats the coolant and, at a same time, removes the residual oxygen from the fuel cell stack,
• wherein the coolant sequentially passing through the coolant pump, the COD and then through the heater core, and
• wherein the COD is at the upstream side of the heater core in a coolant circulation path and the heater core receives coolant that has been heated by the COD prior to being received by the heater core.