Abstract: The invention relates to a device (1) having at least one fuel cell (2) and a DC/DC converter (3) assigned to the latter. A variable voltage generated in the fuel cell (2) is converted, by means of the DC/DC converter (3), into a DC voltage for a system (4) to be supplied. The DC/DC converter (3) is designed to capture internal characteristic variables of the fuel cell (2). Operating states of the fuel cell (2) are captured and/or controlled in dependence on these characteristic variables.

Abstract: An oxygen supply apparatus and method for a fuel cell of an aircraft are provided. The oxygen supply apparatus includes a compressor that generates compressed air by compressing air in the atmosphere and supplies the compressed air to a fuel cell stack, an oxygen tank having a predetermined amount of oxygen stored therein. An aircraft monitoring device monitors the aircraft and determines whether oxygen supply from the oxygen tank is required, and an oxygen supply means switching device switches an oxygen supply means for the fuel cell stack from the compressor to the oxygen tank, or vice versa depending on an outcome of the monitoring.

Abstract: To provide a fuel cell system configured to increase fuel cell performance even at high altitude. A fuel cell system for air vehicles, wherein the fuel cell system comprises: a fuel cell, an oxidant gas system for supplying oxidant gas to the fuel cell, an altitude sensor, and a controller; wherein the oxidant gas system comprises an air compressor and a bypass flow path bypassing the fuel cell; wherein the bypass flow path comprises a bypass valve; and wherein, when the controller detects an altitude increase measured by the altitude sensor, the controller increases a rotational speed of the air compressor, and the controller increases an opening degree of the bypass valve.

Abstract: A fuel cell system performance recovery method includes applying a DC current load pulse waveform to one or more of the fuel cells for a recovery period sufficient to desorb a contaminant from the one or more fuel cells.

Abstract: A cooling water temperature of a fuel cell 10 is detected by a sensor 94d. Based on the outside air temperature, a first threshold temperature and a second threshold temperature lower than the first threshold temperature are calculated. When it is judged that the cooling water temperature is lower than the first threshold temperature and higher than the second threshold temperature, first warmup processing is performed. When it is judged that the cooling water temperature is lower than the second threshold temperature, second warmup processing with an amount of heat generation greater than the first warmup processing is performed.

Abstract: A fuel cell system configured to supply electric power to load includes: a fuel cell; and a control unit configured to set target electric power to be generated by the fuel cell and control electric power generation by the fuel cell such that the fuel cell generates the target electric power. The control unit is configured to, when setting the target electric power using request electric power that the load requests the fuel cell to generate, execute a fluctuation suppression process for making a fluctuation of the target electric power smaller than a fluctuation of the request electric power.

Abstract: A fuel cell system for a vehicle includes a first cooling line configured to pass through a fuel cell stack in a vehicle and configured to circulate a first coolant therein, a first cooler provided in the first cooling line and configured to cool the first coolant, and a second cooler provided in the first cooling line and configured to cool the first coolant independently from the first cooler, thereby obtaining an advantageous effect of ensuring a high output from the fuel cell stack and improving safety and reliability.

Abstract: A fuel cell system to be mounted on a vehicle includes a fuel cell configured to generate electric power through chemical reaction of reactive gases, a gas-liquid separator configured to separate water from an off-gas discharged from the fuel cell and store the separated water, a discharge valve configured to drain the water flowing out through an opening at a bottom of the gas-liquid separator, an attitude control device configured to control an attitude of the gas-liquid separator relative to the vehicle, and an instruction device configured to send an instruction for a control target of the attitude of the gas-liquid separator to the attitude control device.

Abstract: The present disclosure relates to a method of generating energy. This method involves providing a fuel cell comprising anode and cathode electrodes; a separator positioned between the anode and cathode electrodes; and anode and cathode catalysts. The anode catalyst comprises (i) a low-loading of platinum group metals (PGMs) supported on a Group 4-6 transition metal carbide (TMC) or nitride (TMN); (ii) an alloy or physical mixture comprising a Group 10 transition metal selected from Pt, Pd, and Ni and one or more of the following elements: Pt, Pd, Ni, Ir, Rh, Ru, Fe, Re, Sn, W, Mo, Ta, and Nb; or (iii) mixtures thereof. According to the method, a liquid anode fuel comprising one or more hydrazide compounds is added to the fuel cell to generate energy from the liquid anode fuel. Also disclosed is a fuel cell for generating energy from a liquid anode fuel comprising one or more hydrazide compounds.

Abstract: An ion exchange membrane including a first ion exchange resin layer with a first and a second surface; a second ion exchange resin layer on the first surface of the first ion exchange resin layer; and a third ion exchange resin layer on the second surface of the first ion exchange resin layer, wherein the second ion exchange resin layer and the third ion exchange resin layer each independently include an ionomer having a higher equivalent weight (EW) than an ionomer of the first ion exchange resin layer.

Abstract: Prussian blue analog derived catalysts having a composition of highly porous transition metal (“TM”) oxides with nano particle size. Such OER catalysts are synthesized from the PBA, containing cobalt, iron, nickel, copper, manganese, zinc, magnesium etc., as secondary building units (“SBUs”) coordinated by hexacyano-based ligands. Furthermore, the PBA-derived catalysts may also integrated into a highly graphitized carbon network to further improve the conductivity, mass transport and durability against oxidative corrosion.

Abstract: A fuel cell system includes a fuel cell, auxiliary machinery, a tank, a storage amount detection unit that detects a measured value representing the amount of fuel gas stored in the tank, a secondary battery, a power accumulation amount detection unit that detects an amount of power accumulated in the secondary battery, a feed detection unit, and a control unit. The control unit stops the supply of the fuel gas to the fuel cell when the measured value is less than a threshold value, electrically disconnects the secondary battery from the auxiliary machinery when the amount of accumulated power is less than a lower limit amount of accumulated power, and electrically connects the secondary battery to the auxiliary machinery after the feeding of the fuel gas to the tank is detected.

Abstract: A method for preventing an engine overheat based on a coolant temperature applied to an engine system 1 is provided, in which a controller 50 checks if a coolant coming from an engine 10 is distributed to any one of a heater core 25B and an ATF warmer 25A as a radiator 23 is switched from a distribution blocking state (i.e., radiator closed) at a diagnosis start to a distribution state (i.e., radiator open) during the diagnosis under the control of an opening degree of an ITM valve 40, diagnoses lack of a coolant amount using factors B determined by an inlet/outlet coolant temperature difference T of the engine 10 through first and second water temperature sensors 30A and 30B as a factor cumulative value A, and then controls the ITM valve 40 to a full open state in a state where a coolant temperature increase is predicted.

Abstract: The invention relates to a fuel cell system comprising a shut-off element arranged in each case in a supply path and exhaust path of the anode and/or cathode supply, and comprising a gas connection arranged in each case between a shut-off element and a fuel cell stack for connecting to an external test gas supply. The gas connections allow diagnosis and/or maintenance of the fuel cell stack in the installed state.

Abstract: A fuel cell system includes a removal treatment execution unit configured to execute an oxide layer removal treatment that removes an oxide layer generated on a catalyst of a fuel cell. The removal treatment execution unit is configured to execute the oxide layer removal treatment by adjusting a voltage of the fuel cell to be within a predetermined second voltage range lower than a predetermined first voltage range that is lower than an open-circuit voltage, when an operation of the fuel cell system shifts from a first operation, where a current value of the fuel cell is zero and the flow rate is controlled to maintain the voltage of the fuel cell within the first voltage range, to a second operation, where the current value is larger than zero and the flow rate is controlled in response to an output request to the fuel cell.

Abstract: A fuel cell housing case includes: a stack case including a first partitioning plate and a second partitioning plate that separate a space in which a fuel cell stack is to be housed from a space in which a boost converter is to be housed; and a pair of stack bus bars provided on both ends in the stacking direction of the fuel cell stack, wherein the first partitioning plate and the second partitioning plate respectively include: slits through which the respective stack bus bars are inserted; and overlapping portions that overlap each other.

Abstract: The present invention concerns a membrane-less electrolyzer comprising a fluidic channel for receiving an electrolyte fluid; a first electrode and a second electrode located inside the fluidic channel, the first and second electrode permitting to extract a first gas and a second gas inside the fluidic channel from the electrolyte fluid, the first electrode and second electrode being separated by solely a surrounding fluid in the fluidic channel or the electrolyte; and a first fluidic transport channel for transporting the first gas to a first outlet and a second fluidic transport channel for transporting the second gas to a second outlet.

Abstract: Methods, systems, and devices of a control system. The control system includes a fuel cell stack. The control system includes a compressor that is configured to control and provide a total air flow within the vehicle. The compressor has an air pressure ratio and an air flow rate and operates at a speed. The control system includes an electronic control unit coupled to the fuel cell stack and the compressor. The electronic control unit is configured to determine a path associated with one or more adjustments to the air pressure ratio or the air flow rate. The electronic control unit is configured to determine a rate associated with the one or more adjustments based on the path and control at least one of the air pressure ratio, the speed or the air flow rate to operate the compressor based on the path and the rate.

Abstract: An apparatus for preventing moisture condensation includes a fuel cell stack and an enclosure in which the fuel cell stack is disposed. A heater and a temperature sensor are provided in the enclosure. A controller is configured to control the heater to be turned on when an insulation resistance between the fuel cell stack and the enclosure is less than a preset resistance value. The controller controls the heater not to be turned on when a surface temperature of the enclosure measured by the temperature sensor exceeds a preset temperature.

Abstract: A technique that suppresses excessive water drainage from a fuel cell is provided. A water drainage device that drains water from inside of a fuel cell includes: a purge gas supply system; an operation unit; a water drainage controller; and a water content acquirer. The operation unit receives a water drainage command from a water drainage switch configured to control execution of a purge process by the purge gas supply system. When the water content obtained by the water content acquirer is equal to or lower than a predetermined value, the water drainage controller performs either one of: (i) invalidating the received water drainage command; and (ii) changing a processing condition of the purge process to decrease an amount of water drained by the purge process, compared with an amount of water drainage when the obtained water content is higher than the predetermined value.

Abstract: A fuel cell unit includes a fuel cell and a converter. A fuel cell has single cells laminated in a given direction. A converter has a plurality of combinations of a reactor electrically connected with the fuel cell and a power module electrically connected with the reactor. At least either a direction in which first reactors among the reactors are arrayed or a direction in which first power modules among the power modules are arrayed is parallel with a laminating direction of the single cells.

Abstract: A membrane-electrode assembly for water electrolysis including a proton-exchange membrane, a first catalyst layer, a second catalyst layer, a first gas diffusion layer, a second gas diffusion layer and a first sensor chip. The proton-exchange membrane is disposed between an inner side of the first catalyst layer and an inner side of the second catalyst layer. The first gas diffusion layer is disposed on an outer side of the first catalyst layer. The second gas diffusion layer is disposed on an outer side of the second catalyst layer. The first sensor chip is sandwiched between the first catalyst layer and the first gas diffusion layer to sense an environmental change where water electrolysis takes place.

Abstract: An object is to suppress drying of a fuel cell during continuous operation with high load. There is provided a fuel cell system including a fuel cell. The fuel cell system comprises an impedance detector that is configured to detect an impedance of the fuel cell; and a current limiter that is configured to limit an output current of the fuel cell with a limiting rate. The current limiter changes the limiting rate, based on the detected impedance.

Abstract: A device in which an environmental air flow is monitored by a monitoring element and in which a natural gas flow is interrupted by a shut-off element on recognition of an insufficient environmental air flow. To allow a continuous operation of the fuel cell battery the monitoring element is short-circuited by a bridging device and that its operability can thus be checked without the environmental air flow having to be interrupted. This allows a permanent operation of the fuel cell battery.

Abstract: A fuel cell system for a vehicle includes: a fuel cell; a plurality of loads that consumes power generated by the fuel cell and includes a vehicle driving motor; a secondary battery configured to be charged with excess power when an amount of power generated by the fuel cell is greater than an amount of power consumed by the loads and to discharge shortage power when the amount of power generated by the fuel cell is less than the amount of power consumed by the loads; and a control unit configured to control the amount of power generated by the fuel cell such that an amount of charging-discharging power of the secondary battery is maintained at a predetermined value.

Abstract: A fuel cell system comprises: a fuel cell formed of a plurality of cells stacked therein, each cell generating electric power through an electrochemical reaction between a fuel gas and an oxidant gas; a cell monitor capable of detecting a group voltage for each group wherein each group is composed of two or more cells; and an estimation device that estimates a minimum cell voltage. The estimation device comprises a maximum cell voltage estimation part that estimates a maximum cell voltage, and the estimation device estimates the minimum cell voltage by using an estimated value of the maximum cell voltage and a minimum group-average voltage, where an average voltage of a group having the lowest voltage value among the group voltages is defined as the minimum group-average voltage.

Abstract: A fuel cell system includes: a processing unit configured to perform an activation process of temporarily reducing a cathode potential of a single fuel cell to a target potential for a duration time at a processing frequency; a cationic impurity amount estimating unit configured to estimate an amount of cationic impurities included in an electrolyte membrane of the single fuel cell; and a process degree determining unit configured to determine, when the amount of cationic impurities is large, a degree of the activation process which is higher than that determined when the amount of cationic impurities is small by performing at least one action among actions of changing conditions of the activation process, the actions including an action of reducing the target potential, an action of increasing the duration time, and an action of increasing the processing frequency. The processing unit performs the activation process to the determined degree.

Abstract: A fuel cell system comprising: a power generation controller that controls a value subject to control, which is a value exhibiting a power generating state by a fuel cell and is a value that is affected by alternating current applied to the fuel cell, to approach a target value; a dead zone setter that sets a dead zone with the target value as a reference; and, a stopper that stops the control by the power generation controller when the value subject to control is contained in the dead zone.

Abstract: There is provided a fuel cell system. This fuel cell system comprises a fuel cell configured to generate electric power using reactive gases; a voltage sensor configured to measure a voltage output from the fuel cell; a converter configured to boost an input voltage that is input from the fuel cell; and a controller configured to control the converter. In the case where the voltage output from the fuel cell to the converter is to be boosted after a changeover of an operating state of the fuel cell system from an intermittent operation to an ordinary operation, when a duty ratio D1 calculated by Mathematical Formula I is greater than a duty ratio D2 calculated by Mathematical Formula II, the controller causes the converter to boost the voltage output from the fuel cell at the duty ratio D2. [ Math .

Abstract: A method for cooling a fuel cell (3) using a liquid cooling medium, wherein of the starting materials supplied to the fuel cell and the products discharged from the fuel cell, at least one is gaseous during at least one of the operating conditions. The cooling medium is conveyed through the fuel cell (3) by a coolant conveying device (11). The power consumption of the coolant conveying device (11) is compared to predefined reference values in order to detect gas in the liquid cooling medium by a deviation of the power consumption from the predefined reference values.

Abstract: There is provided a control method of an external power supply system configured to supply power to the outside from a fuel cell and a secondary battery mounted on a vehicle. When a failure is detected in a sensor that measures an electric power supplied to the outside from an electric power line to which the fuel cell and the secondary battery are connectable, (a) if a decrease in a state of charge of the secondary battery is detected, external power supply is performed by increasing a generated power of the fuel cell so as to stop the decrease in the state of charge, and (b) if an increase in a state of charge of the secondary battery is detected, external power supply is performed by decreasing the generated power of the fuel cell so as to stop the increase in the state of charge.

Abstract: A system and method for monitoring the conductivity of a cooling fluid flowing in a fuel cell system on a vehicle including a chassis. The fuel cell system includes a fuel cell stack electrically coupled to a stack bus and a battery electrically coupled to a propulsion bus. The method includes operating the fuel cell system, measuring a first isolation resistance at the first power level, measuring a first stack voltage, and measuring a first battery voltage. The method also includes operating the fuel cell system at a second power level, and measuring a second isolation resistance, measuring a second stack voltage, and measuring a second battery voltage. The method calculates a stack coolant resistance using the first and second isolation resistances, the first and second stack voltages, and the first and second battery voltages, which is then used to calculate the cooling fluid conductivity.

Abstract: When a first timing at which a fuel gas is injected to a fuel gas supply flow path by an injector and a second timing at which water residing on a circulation flow path is discharged by controlling rotating speed of a circulation pump coincide with each other, a controller performs either: (i) a first process of operating the circulation pump at a preset RPM without injecting the fuel gas to the fuel gas supply flow path by the injector; or (ii) a second process of injecting the fuel gas to the fuel gas supply flow path by the injector and operating the circulation pump at an RPM lower than the preset RPM.

Abstract: To provide a membrane/electrode assembly excellent in the power generation characteristics even under low or no humidity conditions or under high humidity conditions, and an electrolyte material suitable for a catalyst layer of the 5 membrane/electrode assembly, an electrolyte material is used which comprises a polymer (H) having a unit (A) which has an ion exchange group and in which all hydrogen atoms (excluding H+ of the ion exchange group) bonded to carbon atoms are substituted by fluorine atoms, a unit (B) which has a 5-membered ring and in which all hydrogen atoms bonded to carbon 10 atoms are substituted by fluorine atoms, and a unit (C) which has neither an ion exchange group nor a ring structure, has an ether bond, and has an ether equivalent of at most 350 as established by the following formula (I) and in which all hydrogen atoms bonded to carbon atoms are substituted by fluorine atoms: Ether equivalent=the molecular weight of the monomer forming the unit (C)/the 15 number of ether bonds in the mo

Abstract: Computing devices receive power from multiple fuel cells, consuming natural gas and outputting electrical energy natively consumable by the computing devices. The fuel cells are sized to provide power to a set of computing devices, such as a rack thereof. The computing devices of a failed fuel cell can receive power from adjacent fuel cells. Additionally, the fuel cells and computing devices are positioned to realize thermal symbiotic efficiencies. Controllers instruct the computing devices to deactivate or throttle down power consuming functions during instances where the power consumption demand is increasing faster than the power being sourced by fuel cells, and instruct the computing devices to activate or throttle up power consuming functions during instances where the power consumption demand is decreasing faster than the power being sourced by the fuel cells. Supplemental power sources, supplementing the fuel cells' inability to quickly change power output, are not required.

Abstract: Various hot box fuel cell system components are provided, such as heat exchangers, steam generator and other components.

Abstract: A power generation system of the present invention comprises: a power generation unit (1); a casing (2) that accommodates the power generation unit (1); a ventilator (3) that ventilates the interior of the casing (2); a first gas flow passage (5), arranged inside the casing (2), for a flow therethrough of gas which flows as the ventilator (3) operates; and a second gas flow passage (6), arranged inside the casing (2), for a flow therethrough of combustion exhaust gas from the power generation unit (1), wherein within the casing (2), the second gas flow passage (6) merges into the first gas flow passage (5).

Abstract: Systems, methods, and devices of the various embodiments enable electrochemical impedance spectroscopy (“EIS”) to be performed on electrochemical devices, such as fuel cell stack segments, by power electronics connecting the electrochemical devices in parallel to a common load and/or bus. In an embodiment, the power electronics may compensate for any ripple generated during EIS such that no ripple is realized at the common load and/or bus.

Abstract: A system and method is provided for minimizing the degradation of a fuel cell after shutdown by forcing remaining air out of a fuel cell system. Upon fuel cell shutdown, the flow of air to the cathode of the fuel cell can be kept at a low rate. The flow of cathode exhaust gases along an exhaust conduit is substantially restricted while the pressure of the supply air supplied is increased. As a result, the pressure of the cathode exhaust gases in the exhaust conduit increases. The voltage of the fuel cell can be to deplete the oxygen in the supply air. The pressure of the supply air is decreased to a pressure lower than the pressure of the cathode exhaust gas in the exhaust conduit such that the cathode exhaust gas flows backward through the system to push out any remaining air.

Abstract: The present invention is directed to a humidity controlling ventilator which takes in air through the use of an air blowing fan, and controls the humidity of the taken air via an adsorption heat exchanger prior to supplying it to the room. In the invention, the air blowing fan is controlled so as to make an air volume flow rate approach a predetermined target volume flow rate. To do this, the invention calculates the fan's air volume flow rate based on a specific volume of air downstream of the adsorption heat exchanger and an air mass flow rate of the fan. The calculated value is fed to an air blow controller that is configured to control the fan such that the calculated air volume flow rate approaches the predetermined target air volume flow rate.

Abstract: A stack for a fuel cell system, including: a membrane electrode assembly, a separator that includes a fuel passage that supplies a fuel to an anode electrode of the membrane electrode assembly and an oxidant passage that supplies an oxidant to a cathode electrode of an adjacent membrane electrode assembly, a first manifold that is formed by connecting first penetration holes that penetrate the separator in a stacking direction and that is connected to the fuel passage, a second manifold that is formed by connecting second penetration holes that penetrate the separator in the stacking direction and that is connected to the oxidant passage and a baffle that is disposed in at least one of the first manifold and the second manifold. The baffle has a membrane structure to control the fluid flow inside of the at least one of the first manifold and the second manifold.

Abstract: Provided is a method for shutting down an indirect internal reforming SOFC, in which a hydrocarbon-based fuel is reliably reformed, and the oxidative degradation of the anode can be prevented by a reformed gas.

Abstract: A hybrid silencer in a fuel cell system includes an expansion chamber connected to a predetermined apparatus of the fuel cell system, where the expansion chamber reduces acoustic noise of a fluid discharged from the predetermined apparatus, a water-absorber disposed inside the expansion chamber, where the water-absorber absorbs a liquid component of a fluid which flows into the expansion chamber; and a perforated silencer which discharges the fluid from which the liquid component is removed by the water-absorber while reducing acoustic noise of the fluid discharged therefrom.

Abstract: Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

Abstract: The current invention is a fuel cell controller that includes a first control loop, where the first control loop is disposed to adjust a fuel cell current to regulate a hydrogen output pressure from the fuel cell to a pressure target valve, and further includes a second control loop disposed to adjust a hydrogen flow rate from a hydrogen generator to match a DC/DC power output to a power target value.

Abstract: A system and method for increasing the temperature of a fuel cell stack quickly, especially at cold stack start-up. The method includes determining whether the fuel cell stack is below a first predetermined temperature threshold, and, if so, starting a cooling fluid flow through the stack and engaging a shorting circuit across the stack to short circuit the stack and cause the stack to operate inefficiently. The method then determines a desired heating rate of the fuel cell stack and calculates a cathode airflow to the fuel cell stack based on the desired heating rate. The method reduces the flow of cathode air to the stack if a minimum cell voltage is below a predetermined minimum cell voltage threshold and disengages the shorting circuit and applies vehicle loads to the stack when the stack temperature reaches a predetermined second temperature threshold.

Abstract: A voltage boost converter includes: a main voltage boost portion that has a first switch and a first coil, and that raises output voltage of a direct-current power source by using counter electromotive force of the coil caused by the switch performing a switching action on the coil; and a subsidiary voltage boost portion which has a capacitor that adjusts potential difference between two poles of the switch by amount of electricity stored, and which reduces switching loss of the switch by adjusting the amount of electricity in the capacitor during the switching action, and which has a second switch and a second coil. The second coil is formed by winding a wire around at least a portion of a core formed of a magnetic body. The core is provided with a gap formed of a non-magnetic body. A core region formed of a magnetic body is adjacent to the gap.

Abstract: A fuel cell system, and a method of controlling an operation of a plurality of fuel cells. The fuel cell system controls the operation of the plurality of fuel cells according to a power consumed in a load and the performance of the plurality of fuel cells, thereby increasing a power conversion efficiency of the plurality of fuel cells while preventing considerable performance degradation of the plurality of fuel cells. The fuel cell system includes: a plurality of fuel cells; a control unit controlling an operation of the plurality of fuel cells according to a power consumed in a load and the performance of the plurality of fuel cells; and a converter converting a power output by at least one of the plurality of fuel cells into a power according to the control of the control unit.

Abstract: The object of this invention is to provide a fuel supply system capable of reducing the quantity of a fuel to be discharged from a plurality of fuel tanks connected in parallel is provided. The fuel supply system includes a plurality of the fuel tanks for storing a fuel, on-off valves provided individually for the fuel tanks, and a control unit which controls the opening and closing of the on-off valves. The control unit changes the number of the on-off valves to be simultaneously opened according to a situation. The control unit may reduce the number of the on-off valves to be simultaneously opened after a failure is detected or at the time of maintenance of the fuel supply system.

Abstract: A method for providing calibration and synchronization pulses in a pulse width modulation (PWM) signal including cell voltage measurement pulses, where the calibration pulses are four calibration pulses having a pattern of a narrow width high voltage pulse followed by a wide width low voltage pulse followed by a narrow width high voltage pulse followed by a wide width low voltage pulse that has a very low probability of occurring in a practical fuel cell system. The method modulates a combined sequence of the voltage measurement signals and the calibration pulses using an inverted saw tooth wave to provide the PWM signal, where a width of the pulses representing the voltage signals are proportional to a width of the pulses representing the calibration pulses.