A fuel cell system includes: a converter that boosts a voltage input from a fuel cell; a voltage control device that can control a voltage input from an electricity storage unit; a drive circuit that converts direct-current electricity input from the converter and the voltage control device into alternating-current electricity and outputs the converted electricity to the load; a relay that switches between a connected state in which the fuel cell and the drive circuit are connected to each other and a disconnected state in which they are disconnected from each other; and a controller that determines whether the relay is welded by different determination methods using an index current value between the relay and the fuel cell and a first index voltage value between the relay and the converter when the fuel cell system is to be stopped.

A method of controlling an air compressor motor for a fuel cell vehicle is provide. The method includes calculating a counter electromotive force constant of the air compressor motor based on a voltage and a current of the air compressor motor for the fuel cell vehicle supplying air to a fuel cell stack and a rotation speed of the air compressor motor. The method additionally includes determining whether a permanent magnet of the air compressor motor is demagnetized based on a result of comparison between the calculated counter electromotive force constant value and a pre-set counter electromotive force constant design value.

A method of controlling the driving of a fuel cell system includes: determining whether the fuel cell system enters idle stop in which air supply to the fuel cell stack stops; dropping a DC-link terminal voltage controlled by a DC-DC converter up to a first set voltage by controlling an operation of the DC-DC converter connected to a DC-link terminal outputting generation power of the fuel cell stack at the time of entering the idle stop; and dropping a voltage of the fuel cell stack to reduce an oxide of platinum which is a catalyst of a fuel cell by allowing the anode exhaust gas to flow backward into a cathode of the fuel cell stack by performing the hydrogen purge in an idle stop state of opening the hydrogen purge valve after the voltage of the DC-link terminal drops.

A system and method are provided for controlling a plurality of fuel cells. The method includes coordinating a distribution of a power demand in response to a power request of a power system comprising a plurality of fuel cells, the power output of each of the fuel cells selected based on a respective efficiency of each of the fuel cells.

A fuel cell oxygen delivery system, method, and apparatus for full-scale clean fuel electric-powered vehicle having a fuel cell module including a plurality of fuel cells working together that augments gaseous oxygen from ambient air and gaseous hydrogen extracted from liquid hydrogen by pressure change or heat exchangers, with fuel cells containing electrical circuits configured to collect electrons from the plurality of hydrogen fuel cells to supply voltage and current to motor controllers commanded by control units configured to control an amount and distribution of electrical voltage and torque or current for each of one or more motor and propeller or rotor assembly, wherein electrons returning from the electrical circuits combine with both oxygen derived from air and onboard oxygen from the delivery system to form oxygen ions, then protons combine with oxygen ions to form H.sub.2O molecules and heat.

Provided is an electric vehicle system/general vehicle system having a sudden unintended acceleration prevention function, the system comprising: an auxiliary fuel tank mounted to a vehicle; a hydrogen generation means for receiving fuel from the auxiliary fuel tank so as to generate hydrogen; a stack for receiving hydrogen generated by the hydrogen generation means so as to generate power; a voltage level change unit for changing the voltage level of power generated by the stack; a main battery and an auxiliary battery which are charged by a charging voltage output from the voltage level change unit; a control unit driven by power output from the auxiliary battery; and a drive load unit including a drive motor driven by power output from the main battery or the stack.

A vehicle system of the present invention includes: a motor configured to drive a vehicle; a high voltage storage device connected to the motor and configured to supply the motor with power; a fuel cell connected to the high voltage storage device and configured to charge the high voltage storage device; and a low voltage storage device connected to the fuel cell. The vehicle system includes: a bidirectional first voltage converter interposed between the fuel cell and the high voltage storage device, and configured to adjust a voltage at either of the fuel cell or the high voltage storage device and to supply power to the other; and a second voltage converter interposed between the fuel cell and the low voltage storage device, and configured to adjust a voltage at the low voltage storage device and to apply the adjusted voltage to the fuel cell. The vehicle system is characterized in that the vehicle system includes a bidirectional third voltage converter interposed between the high voltage storage device and the low voltage storage device, and configured to adjust a voltage at either of the high voltage storage device or the low voltage storage device and to supply power to the other.

A power supply device includes: a power supply mounted in an apparatus; a conversion module including a plurality of conversion units configured to perform voltage conversion of power supplied by the power supply, the plurality of conversion units being electrically connected in parallel to each other; a selection unit that selects one of a plurality of patterns indicating a combination of the conversion units performing the voltage conversion for each operation number, which is the number of the conversion units performing the voltage conversion; and a control unit that controls the conversion module such that the conversion unit indicated by the pattern selected by the selection unit performs the voltage conversion. The selection unit changes the selected pattern with an operation on the switch. In the plurality of patterns, the combination of the conversion units performing the voltage conversion in at least one of the operation numbers is different.

A fuel cell system comprises an electrochemical fuel cell stack for generating electrical power. A load circuit is switchably coupled to the fuel cell stack for periodically receiving a discharge current from the fuel cell stack during an energy dissipation phase, such as an air stall operation for conditioning the fuel cell stack. A protection circuit is coupled to the load circuit, configured to monitor a cumulative energy dissipation level during an energy dissipation phase and to abort an energy dissipation phase if the cumulative energy level reaches a predetermined threshold. In this way, lower specification resistor components can be used for stack conditioning.

A fuel cell system includes: a converter that boosts a voltage input from a fuel cell; a voltage control device that can control a voltage input from an electricity storage unit; a drive circuit that converts direct-current electricity input from the converter and the voltage control device into alternating-current electricity and outputs the converted electricity to the load; a relay that switches between a connected state in which the fuel cell and the drive circuit are connected to each other and a disconnected state in which they are disconnected from each other; and a controller that determines whether the relay is welded by different determination methods using an index current value between the relay and the fuel cell and a first index voltage value between the relay and the converter when the fuel cell system is to be stopped.