Abstract: The fuel cell system includes a fuel cell; a power conditioner that converts a cell power supplied from the fuel cell to a power corresponding to a load; a capacitor to which an excessive output power of the fuel cell is charged at the time of a low load operation and from which a power corresponding to the insufficient output power of the fuel cell is discharged at the time of a high load operation; a voltage detection means for detecting a voltage of the capacitor; and a control means that determines the low load operation or the high load operation, calculates an output power from the fuel cell to maintain the excessive power generated at the time of the low load operation within a space capacity of the capacitor, and controls the output power of the fuel cell not to exceed the calculated value.

Abstract: The electrical output connections (155, 158) of a fuel cell stack (151) are short circuited (200; 211, 212) during start up from freezing temperatures. Before the stack is short circuited, fuel is provided in excess of stoichiometric amount for a limiting stack current, and oxidant is provided to assure stoichiometric amount for the limiting stack current.

Abstract: A fuel cell system that has a fuel cell stack with a plurality of laminated cells, each of the laminated cells includes an electrolyte membrane interposed between a fuel electrode receiving a supply of fuel gas and an oxidizing agent electrode receiving a supply of oxidizing agent gas. A fuel gas supply device supplies a fuel gas to the fuel electrode. An oxidizing agent gas supply device supplies an oxidizing agent gas to the oxidizing agent electrode. A fuel electrode side discharge system discharges a discharge gas from the fuel electrode to an external. A circulation device re-circulates the discharge gas discharged from the fuel electrode into an upstream side of the fuel electrode. A voltage limit device limits a voltage across the fuel cell stack by drawing a current from the fuel cell stack at a time of an activation of the fuel cell system.

Abstract: The disclosure relates to a fuel cell device arrangement for producing electrical energy, having at least one fuel cell anode and cathode, an electrolyte for conveying ions between the anode and the cathode, and a passage separate from the electrolyte for the electrons travelling from the anode to the cathode. A control arrangement can prevent the formation of carbon by calculating a thermodynamic equilibrium model based on thermodynamic equilibriums of chemical reactions for the feedback recirculation of fuel. Measurement values are obtained, at least from the electric current and the fuel flow rate, for calculating the fuel composition. Conversion values set on the basis of the thermodynamic equilibrium model for the fuel are calculated using the measurement values and fuel composition.

Abstract: A fuel cell system capable of performing activation for stabilizing electrical characteristics of a fuel cell with suppressing generation of polarity inversion associated with drying of a polymer electrolyte membrane and excess power consumption. An activation method for a fuel cell, the fuel cell system including a fuel cell having a fuel electrode and an oxidizer electrode that are provided on both sides of a polymer electrolyte membrane; a resistance detector for detecting an internal resistance of the fuel cell; a load connection portion having a mechanism for connecting a resistor between the fuel electrode and the oxidizer electrode; and a control unit for controlling the load connection portion. The control unit controls the operation of the load connection portion based on a value of the inner resistance of the fuel cell, which is detected by the resistance detector.

Abstract: A fuel cell system (100) is provided with a voltage detection device (41) that detects a cell voltage of a cell group containing one or more cells (11), a current density detection device (42) that detects a generated current density of the cell group, and a determination portion (52) that determines the presence or absence of an inflection point of a change in the cell voltage relative to the generated current density based on the detection results of the voltage detection device and the current density detection device.

Abstract: A fuel cell system that is able to perform power generation more stably than in the past regardless of external environment is provided. Based on a temperature of a power generation section detected by a temperature detection section, a supply amount of a liquid fuel from a fuel pump is adjusted, and therefore control in which the temperature of the power generation section becomes constant is performed. In addition, a fuel cell system that is able to perform power generation in a vaporization supply type fuel cell more stably than in the past is provided. A level of a power generation voltage supplied from the power generation section is raised by a boost circuit. In a control section, operation of the boost circuit is controlled using a given control table, and therefore control is performed on an output voltage and an output current supplied from the boost circuit to a load.

Abstract: During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.

Abstract: A system and method for limiting the output current of a fuel cell stack as the stack degrades overtime. A look-up table identifies a predetermined voltage set-point for stack current density. A first comparator provides a voltage difference signal between the set-point and the stack voltage. The voltage difference signal is provided to a controller, such as a proportional-integral controller, that provides a current limiting signal. The current limiting signal and a current request signal are provided to a second comparator that selects which signal will be used to limit the maximum output current of the stack. A polarization curve estimator estimates parameters of the stack that will change over the life of the stack. The parameters are provided to a gain scheduler that provides gains to the controller that are based on where in the life of the stack it is currently operating.

Abstract: A control algorithm for operating an integrated fuel cell system includes the following steps: determining whether a power output of a fuel cell is within a first predetermined range of an electrical load coupled to the fuel cell; lowering a reactant flow to the fuel cell when the power output is within the first predetermined range; detecting an increase of the electrical load; determining whether the increase exceeds a second predetermined range; and increasing a reactant flow to the fuel cell when the increase exceeds the second predetermined range.

Abstract: There is disclosed a fuel cell system which can control an output current of a fuel cell even if an error occurs in split flow control of an oxidizing gas. The fuel cell system includes a fuel cell and a feed device for supplying the oxidizing gas under pressure to the fuel cell. A feed channel is connected to a discharge channel by a bypass channel so that the oxidizing gas flows while bypassing the fuel cell. The system includes a regulator valve and a bypass valve which adjust the split flow of the oxidizing gas to the bypass channel and the fuel cell. When the regulator valve or the bypass valve has an error, a controller stops the control of the output current of the fuel cell by control of the regulator valve and switches the control to a control of the output current of the fuel cell by control of the feed device.

Abstract: It is possible to prevent excessive power generation of a fuel cell when a failure has occurred. When a start signal is input, a fuel cell system sets an open end voltage of the fuel cell as an initial value of the output voltage of the fuel cell corresponding to the output current zero of the fuel cell. When the failure is detected, the fuel cell system reads out the open end voltage of the preset initial value as the output voltage corresponding to the output current zero and controls the voltage so that the output voltage of the fuel cell coincides with the open end voltage.

Abstract: The method of operating a passive hybrid power supply in, or near, zero connected load conditions comprises the steps of: supplying a stream of substantially pure hydrogen to the anode of the fuel cell; supplying an stream of substantially pure oxygen to the cathode of the fuel cell; monitoring an electric current supplied by the storage battery; monitoring an output voltage shared by the fuel cell and the battery; evaluating a state of charge (SOC) of the battery based on the electric current and the output voltage; monitoring a hydrogen pressure in the fuel cell; monitoring an oxygen pressure in the fuel cell; limiting the stream of hydrogen and the stream of oxygen and actuating the hydrogen and oxygen recirculating pumps in such a way as to bring and maintain the hydrogen and oxygen pressures below 0.7 barabsolute while maintaining the hydrogen pressure between 70 and 130% of the oxygen pressure, in such a way as to ensure that the output voltage is maintained at a level corresponding to less than 0.

Abstract: The present invention relates to a fuel cell system that is capable of running a detailed diagnostic check on the internal dryness of a fuel cell. The fuel cell system measures the distribution of electrical current density on a power generation plane of the fuel cell, and diagnoses the internal dryness of the fuel cell in accordance with changes in the peak position of electrical current density on the power generation plane. If the fuel cell is configured to let a reactant gas (hydrogen) on the anode side and a reactant gas (air) on the cathode side flow in opposing directions with the power generation plane positioned in between, the fuel cell system judges whether the peak position of electrical current density is displaced toward the outlet of an anode or the outlet of a cathode. In accordance with the result of judgment, the fuel cell system can determine whether dry-up has occurred on the anode side or cathode side.

Abstract: A method and an apparatus for controlling the operation of a fuel cell system. The method can include, actively controlling the fuel cell system without a fuel concentration sensor by: measuring an output voltage, an output current, and a temperature of a fuel cell stack; obtaining a first fuel feeding amount corresponding to the measured output values; comparing a reference temperature corresponding to the measured output values with the measured temperature; and obtaining a second fuel feeding amount by compensating the first fuel feeding amount with a value corresponding to difference between the reference temperature and the measured temperature.

Abstract: A fuel cell system which includes: a fuel cell (1); a supply system (Sc) for supplying fuel gas to the fuel cell (1); a recirculation system (Rc) for recirculating unused fuel gas from the fuel cell (1), in which the fuel gas therein may contain nitrogen; a purge valve (8) for purging nitrogen contained in the fuel gas in the recirculation system (Rc); and a controller (100) for adjusting a valve opening of the purge valve (8) so that a nitrogen concentration of the fuel gas in the recirculation system (Rc) is kept constant.

Abstract: A method for managing fuel cell power increases in a fuel cell system using an air flow feedback delay. The method comprises the steps of determining a required air mass flow rate at a predetermined point in the fuel cell system, determining an actual air mass flow at a predetermined point in the fuel cell system, calculating an air flow feedback delay as a function of the required air mass flow rate and the actual air mass flow, and delaying an external circuit from increasing current draw from the fuel cell stack by the magnitude of the air flow feedback delay.

Abstract: The present invention provides a method for supplying fuel to a fuel cell, in which a monitoring period is determined for monitoring the fuel cell, and then a feeding amount of fuel is determined by integrating characteristic value generated from the fuel cell in the monitoring period. In another embodiment, it is further comprising a step of determining the variation profile associated with the characteristic value during the period so as to judge whether it is necessary to feed the fuel into the fuel cell or not. By means of the present invention, the supplying of fuel to the fuel cell under dynamic loadings can be effectively controlled for optimizing the performance of the fuel cell as well as reducing the cost without installing any fuel sensor.

Abstract: A fuel cell vehicle includes a fuel cell, a storage battery, a fuel-cell-output-controller, and a remaining-capacity-detector. An output of the fuel cell is supplied to a load. An output of the storage battery is supplied to the load. The fuel-cell-output-controller is configured to control the output of the fuel cell. The remaining-capacity-detector is configured to detect a current remaining capacity in the storage battery. The fuel-cell-output-controller is configured to determine and control a reference output value for the output of the fuel cell in accordance with a change in the current remaining capacity in the storage battery, and configured to increase the reference output value as an output of the load becomes higher referring to a state of the output of the load for a specific period of time.

Abstract: A method of estimating a lifespan of a fuel cell including a cathode and an anode which contain catalysts and an electrolyte membrane interposed between the anode and the cathode. A cyclic potential with a voltage ranging from a low voltage to a voltage greater than oxidation voltages of the catalysts is applied between the anode and the cathode and fuel cell performance is measured initially and after a predetermined number of cycles. The lifespan of the fuel cell may estimated based on degradation of cell performance after the predetermined number of cycles, based on CV curves obtained during the cycling of the potential and/or a change in particle size of the catalysts after the predetermined number of cycles.

Abstract: A method for shutting down an electricity supply system comprising a fuel cell, the cell being supplied with pure oxygen as the combustive gas and delivering an electric voltage to an electric power line, the system comprising a fuel gas feed circuit on the anode side and an oxygen feed circuit on the cathode side, the oxygen feed circuit comprising means that enable the said oxygen feed circuit to be opened to the atmosphere and means for delivering a stop signal to a control unit of the fuel cell. The shutting down procedure is activated on reception of a stop signal and comprises an initial stage during which the supply of oxygen is interrupted, a consumption stage during which a sustained current is drawn from the fuel cell, a neutralisation phase during which the oxygen feed circuit is opened to the atmosphere, and a final stage during which the supply of hydrogen is interrupted.

Abstract: The fuel cell system includes a fuel cell stack, a fuel cell temperature sensor for measuring the internal temperature of the fuel cell, a voltage sensor for measuring the power generation voltage of the fuel cell, a current sensor for measuring the current flowing from the fuel cell, a radiator for radiating heat generated by the fuel cell, a fan attached to the radiator for controlling the heat radiation amount, a cooling water pump for increasing the pressure of a cooling fluid, a bypass valve for controlling the cooling fluid amount entering the radiator, and a controller, on the basis of the voltage information measured by the voltage sensor, the temperature information measured by the temperature sensor, and the current information measured by the current sensor, for controlling at least one of the operation amount of the cooling water pump, the operation amount of the fan, and the cooling fluid amount flowing through the bypass valve.

Abstract: A flow control valve for a fuel cell that has particular application for controlling the flow of cathode air through a cathode flow channel of the fuel cell. The valve includes an element that controls the flow through the flow channel in response to changes in the voltage potential of the fuel cell. The valve includes a shape memory alloy wire and a flow control element secured to both ends of the shape memory alloy wire. The ends of the wire are also coupled to the anode and cathode of the fuel cell. When no current is flowing through the wire, the flow control element holds the wire in a pre-strained condition. If the voltage generated by the fuel cell increases, the current passing through the wire will heat the wire and cause it to shrink or contract which forces the flow control element into the flow path.

Abstract: A fuel cell system and its control method capable of removing condensed water only from a place where flooding is generated, without deteriorating an electrolyte membrane. The electrolyte membrane (10) which is a solid high-molecular membrane is sandwiched by an anode (12) and a cathode (14) and these are sandwiched by collectors (16). Furthermore, these are sandwiched by separators (18), thereby constituting a fuel cell (30). Heating means is arranged on the separator (18) and its switch (20) is turned ON when the moisture for hydration of the electrolyte membrane (10) is condensed, so that current is supplied to the heating means from a power source (22) so as to evaporate the condensed water. This rapidly eliminates flooding.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, such as which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. In some systems, fuel not used by the fuel cell stack is discharged through at least one exit orifice at an exit pressure. In some examples, a control system is adapted to control operation of one or both of the fuel source and the fuel cell stack based on the flow of unused fuel. In some examples, a target pressure is determined based on the level of electrical current produced by a fuel cell stack, such that when fuel is supplied at the target pressure, the fuel cell stack consumes a given proportion of the supply fuel.

Abstract: A power supply apparatus has a fuel cell unit as a source of input power. A control device limits the output of the fuel cell unit within an operating range of up to a maximum power point, even if a load power is not lower than the maximum power of said fuel cell unit. In addition to the fuel cell, a charge storing device is provided at the output side of the power supply apparatus. The charge storing device is capable of making up a shortage of power of the fuel cell.

Abstract: A method for revising a reference polarization curve of a fuel cell stack that identifies the relationship between the voltage and the current of the stack over time. When the stack is operating at a low load where kinetic voltage losses of the stack dominate, a first adaptation value is revised as the difference between the actual stack voltage and the stack voltage of the reference polarization curve. When the stack is operating at higher loads where ohmic voltage losses of the stack dominate, a second adaptation value is revised as the difference between the actual stack voltage and the stack voltage of the reference polarization curve.

Abstract: A method for controlling the current output from a fuel cell stack to prevent the stack voltage or the minimum fuel cell voltage from dropping below predetermined voltage set-points. The method for the stack voltage control includes determining whether the stack voltage has dropped to the predetermined voltage set-point, and if so, capturing and holding the actual stack current at that point as the maximum allowed stack current. If the stack voltage continues to fall below the voltage set-point, then the voltage set-point is subtracted from the actual voltage to get a positive error signal. Controller gains are then multiplied by the error signal to reduce the current allowed from the stack to drive the error signal to zero, and increase the stack voltage. The method for the minimum fuel cell voltage operates in the same manner, but with different values.

Abstract: One object is to provide a measuring device configured to evaluate the power generation characteristics of a response-delay type fuel cell automatically, precisely, and with excellent reproducibility with consideration of the response delay against power load fluctuations, and effectively acclimatize and develop microorganisms that are provided to generate power. A potentio-galvanostat is connected to a microbial fuel cell provided as an exemplary response-delay type fuel cell. Further, an automatic measuring device is connected to the potentio-galvanostat. The automatic measuring device has a program function and measures the internal resistance of the microbial fuel cell at set time.

Abstract: In a power supply with n interlaced conversion cells, a control device activates m paths out of n paths, 1?m?n, as a function of the power or of the current handled by the power supply. The cell may have a boost, buck, buck/boost, Cuk, or SEPIC topology.

Abstract: A fuel cell system which includes: a fuel cell fed with a reaction gas for generating power; an output detection unit which detects output current and voltage of the fuel cell; a storage unit which stores a standard current-voltage characteristic of the fuel cell, from which a standard voltage of the fuel cell at an output current thereof is obtainable; and a gas feed mismatch detection unit which detects a gas feed mismatch of the reaction gas, based on a comparison between the detected output voltage of the fuel cell and the standard voltage at the detected output current, obtained from the standard current-voltage characteristic stored.

Abstract: A method for operating a fuel cell system connected to a power grid includes determining a frequency of the power grid, and adjusting the operation of the fuel cell system based on the determined frequency.

Abstract: A method of starting a fuel cell stack in subzero conditions that minimizes start times while avoiding cell reversal by using an iterative model to determine the optimal current density time profile for startup.

Abstract: An isolation fault detection system for detecting isolation faults in a fuel cell system associated with a fuel cell hybrid vehicle. The isolation fault detection system measures a stack voltage potential, a positive fuel cell voltage potential, a negative fuel cell voltage potential, a positive battery voltage potential, and an overall battery voltage potential. The isolation fault detection system then uses these voltage potentials in mesh equations to compare the measured voltage potentials to voltage potentials that would occur during a loss of isolation. In one embodiment, the isolation fault detection system uses these five measured voltage potentials to determine whether an isolation fault has occurred at four separate locations in the fuel cell hybrid vehicle. The system also can detect the location of the isolation fault.

Abstract: A fuel cell power system comprises an internal or self-regulating control of a system or device requiring a parasitic load. The internal or self-regulating control utilizes certain components and an interconnection scheme to produce a desirable, variable voltage potential (i.e., power) to a system or device requiring parasitic load in response to varying operating conditions or requirements of an external load that is connected to a primary fuel cell stack of the system. Other embodiments comprise a method of designing such a self-regulated control scheme and a method of operating such a fuel cell power system.

Abstract: A system includes a fuel cell stack, a power communication path, a first controller and a second controller. The fuel cell stack generates electrical power, and the power communication path is coupled between the fuel cell stack and a load of the system to communicate the electrical power to the load. The power communication path includes a switch, which is operable to selectively couple the fuel cell stack to the load and isolate the fuel cell stack from the load. The first controller has a first response time to control the fuel cell stack and control the power communication path. The second controller has a second response time, which is significantly less than the first response time to monitor the power communication path for a fault condition and take corrective action in response to detecting the fault condition.

Abstract: The present invention discloses a power supply apparatus and method for a line connection type fuel cell system. The power supply apparatus for the line connection type fuel cell system includes: a storing unit for pre-storing a normal region and a warning region according to an operating condition of a fuel cell and a correlation between an output voltage and an output current of the fuel cell; and a control unit for detecting an operating point on the basis of the operating condition of the fuel cell, comparing the detected operating point with the normal region and the warning region, and outputting a control signal for increasing or decreasing the output current of the fuel cell according to the comparison result.

Abstract: A method of optimizing a waveform of an electrical current applied to an electrode of an electrochemical device that consists of at least two electrodes separaged by an electrolyte that includes the steps of: applying an electrical current to an electrode of a device; determining a waveform of the voltage or the current of the electrical current; representing the waveform by a mathematical expression or numbers taking measurements of output voltage, current or power of the device associated with the application of the electrical current; and varying the shape and frequency of the waveform to optimize the output voltage, current or power of the device and thereby determine an optimized waveform of the electrical current to be applied to the electrode of the device.

Abstract: A method of purging a fuel cell is disclosed. The method includes determining a running average current load on the fuel cell, a standard deviation of cell voltages of the fuel cell and/or a maximum change in cell voltage of the fuel cell. The fuel cell is purged if the running average current load exceeds an average current load standard, the standard deviation of cell voltages exceeds a standard deviation threshold value, or the maximum change in cell voltage exceeds a maximum allowed cell voltage change rate.

Abstract: A fuel cell system has a fuel cell stack, a controller, and a cooling water channel. The controller executes the control for the temperature of cooling water flowing through the cooling water channel in the fuel cell stack. When judging the necessity to increase an oxygen concentration of air at an area near an air outlet of the air channel, the controller instructs to change a temperature of the cooling water to a condense available temperature at which water vapor involved in the air at the area near the air outlet can be condensed in order to increase the oxygen concentration in the air at the area near the air outlet. As a result, the magnitude of the electric power generated by the fuel cell stack is increased efficiently.

Abstract: A system for a vehicle having an engine with an exhaust comprises a fuel cell coupled in the engine exhaust wherein the fuel cell has an output circuit; a battery coupled with the fuel cell; and a controller receiving a signal indicative of an electric output of the fuel cell output circuit, and adjusting one of the fuel amount and the air amount supplied to the engine in response to said signal to affect air-fuel ratio of the exhaust of the engine.

Abstract: A method of operating a fuel cell system during a fuel outage or shortage includes detecting an open circuit voltage (OCV) of the fuel cell system, and providing a reducing purge gas flow to anode electrodes of fuel cells of the fuel cell system when the OCV approaches, reaches or falls below a threshold value below which oxidation of the anode electrodes occurs.

Abstract: A fuel cell power generation system which adjusts the amount of fuel, in a fuel cell power generation apparatus, into a predefined range is provided. A fuel cell system includes a fuel cell power generation apparatus, a control means which has the fuel cell power generation apparatus output a preset electric power value, and a power supply unit which charges and supplies an electric power to an external. The control means changes the electric power value outputted from the fuel cell power generation apparatus, based on the status of liquid fuel detected by a fuel state detecting means.

Abstract: A system and method for reducing RH cycling of the membranes in a fuel cell stack. A control algorithm damps a power request signal using a first order filter during low power transients so that the fuel cell stack continues generating power at a higher rate than is requested. The excess power generated by the stack is used to recharge a battery in the fuel cell system. The damped power signal is weighted so that more fuel cell stack power is provided for a low battery state of charge unless stack power is provided for a high battery state of charge.

Abstract: Provided is a fuel cell system which can measure an air blow interval and consider an exceptional condition such as a high-potential-avoiding operation, thereby enabling an accurate judgment of degradation of an electrolyte. An actual air blow time interval is measured while estimating a theoretical air blow time interval when an increase of a hydrogen consumption amount corresponding to a cell voltage in the high-potential-avoiding operation according to an output current by using a relationship table which contains a record of a relationship between a hydrogen consumption amount consumed for maintaining the function of a fuel cell and the air supply time interval varying with the increase of the hydrogen consumption amount. The degradation of the electrolyte of the fuel cell is judged according to whether the measured actual air blow time interval is shorter than the theoretical air blow time interval corresponding to the hydrogen consumption amount.

Abstract: A fluid regulating microvalve assembly for use to control fluid flow to a fluid consuming electrode, such as an oxygen reduction electrode, in an electrochemical cell. The microvalve assembly includes a stationary valve body having an aperture and a microactuator movable from a first position where the microvalve body aperture is closed to fluid flow to at least a second position where fluid is able to pass through the microvalve body aperture. The fluid regulating microvalve assembly can utilize cell potential or a separate source to open and close the microvalve. The fluid regulating microvalve assembly can be located outside the cell housing or inside the cell housing, for example between one or more fluid inlet apertures and the fluid consuming electrode. The invention includes a method of making a multilayer microvalve assembly, particularly one for use in a fluid depolarized battery, using a printing process to deposit at least one of the layers.

Abstract: Provided is a fuel cell system that can suitably control a voltage converter in response to a judgment that an abnormal condition occurs in a power detection unit that detects a power passing through the voltage converter. The fuel cell system has: a first power detection unit that estimates an effective value of a converter input power by multiplying the converter input power, which is obtained from a battery voltage and a battery current, by a converter efficiency; a second power detection unit that estimates a converter output power from a fuel cell voltage, a fuel cell current and a driving motor load power; and a third power detection unit that estimates a converter flowing power from a current of a reactor measured by a current sensor (shown in a separate drawing). The fuel cell system also has similar detection units for current, and using one of the detection units or a combination of some of them, specifies a malfunctioning sensor and prohibits correction of parameters.

Abstract: Even if a failure occurs in a bypass valve during low-efficiency power generation, the occurrence of an excessive stoichiometry ratio in a fuel cell can be prevented. An output from a pressure sensor or a current sensor is monitored by a control device, and when a failure associated with a closed-valve malfunction of the bypass valve occurs, the degree of opening of the pressure regulating valve is increased to increase an amount of cathode-off gas exhaust, and a revolution speed of an air compressor is reduced to an amount of air discharged by the air compressor, thereby preventing an excessive stoichiometry ratio in the fuel cell.

Abstract: A power management module adapted to be connected between a fuel cell and an output power bus, the power management module being operative to regulate the amount of power being delivered by the fuel cell to the output power bus.

Abstract: A fuel cell system has a fuel cell stack generating electricity with a reactive gas supplied thereto and a controller supplying to the fuel cell stack the reactive gas whose pressure is higher than a normal operational pressure on condition that a temperature of the fuel cell stack is equal to or less than a predetermined threshold temperature and that a moisture content of the fuel cell stack is equal to or less than a predetermined threshold value. Where a supply pressure of the reactive gas is raised, an amount of moisture taken away by the reactive gas becomes less, and thus, water balance within the fuel cell stack shifts toward accumulation of moisture contained in the reactive gas into the film-electrode joined body. However, since the moisture content of the fuel cell stack is equal to or less than the predetermined threshold value, the system can improve the starting performance of the fuel cell stack at low temperature while suppressing flooding.