NOVELTY - The method involves receiving a command for a current threshold value in a high-voltage battery (500) of a fuel cell control unit (100) by a bi-directional transducer (200) while a fuel cell vehicle is driven. Judgment is made to check whether the fuel cell vehicle is switched into a pre-determined mode by the bi-directional transducer. The current threshold value is changed by the transducer. Pre-determined control process is carried out based on changed current threshold value, if the fuel cell vehicle is switched into the pre-determined mode.    USE - Method for controlling a fuel cell vehicle. Uses include but are not limited to a motor vehicle such as passenger car, sport utility vehicles (SUV), bus and lorry, a watercraft, a boat, a ship, a aircraft, a hybrid vehicle, a electric vehicle i.e. plug-in-hybrid electric vehicle, hydrogen-propelled vehicle and a petrol-driven and electrical propelled vehicle.    ADVANTAGE - The method enables carrying out pre-determined control process based on changed current threshold value, if the fuel cell vehicle is switched into the pre-determined mode so as to monitor state of the fuel cell vehicle in real time through the bi-directional transducer, thus enhancing control responsiveness of the fuel cell vehicle in a transition state and realizing effective control efficiency of energy flow of a fuel cell system and the high-voltage battery. The bi-directional transducer performs super-ordinate control process over the bi-directional transducer in the transition state so as to realize quick energy conversion in the fuel cell vehicle.    DETAILED DESCRIPTION - The pre-determined mode is an utilizable braking mode or regenerative brake mode and a sudden acceleration mode. INDEPENDENT CLAIMS are also included for the following:    (1) a system for controlling a fuel cell vehicle    (2) a non-volatile machine-readable medium comprising set of instructions for controlling a fuel cell vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a system for controlling a fuel cell vehicle. '(Drawing includes non-English language text)'    Fuel cell control unit (100)    Bi-directional transducer (200)    Fuel cell system (300)    Inverter (400)    High-voltage battery (500)