An apparatus and a method for measuring the internal ohmic resistance of a fuel cell system, in which the resistance can be easily measured through a current interruption method even while the fuel cell system is operated. An interrupter and an external energy consumption device are connected in parallel to each other between a fuel cell and a main energy consumption device such that current to the external energy consumption device is applied and interrupted by switching the interrupter on/off even while the fuel cell system is maintained in operation as is, thereby making it possible to easily measure the internal ohmic resistance of the fuel cell.

Various embodiments manage a fuel cell IT grid system to maintain fuel cell temperatures above a threshold temperature. The system may include power modules each including a fuel cell, DC/DC converters each connected to a power module, a DC power bus connected to the DC/DC, IT loads each connected to the DC power bus, a load balancing load connected to the DC power bus, and a control device connected to a first power module. The control device may determine whether a temperature of the first power module exceeds the temperature threshold, determine whether an electrical power output of the power modules exceeds an electrical power demand of the IT loads in response to the temperature exceeding the temperature threshold, and direct excess electrical power output to the load balancing load in response to the electrical power output exceeding the electrical power demand.

A solid oxide fuel cell system includes at least a solid oxide fuel cell that generates, through an electrochemical reaction, electric power from anode gas and cathode gas containing oxygen, a combustor that burns anode off-gas and cathode off-gas both discharged from the solid oxide fuel cell, and that produces exhaust gas, a purifier that is heated by heat of the exhaust gas produced by the combustor, and that includes a purification catalyst to remove substances to be cleaned up, those substances being contained in the exhaust gas, and a controller. The controller raises the temperature of the purifier to 300 C. or higher for a predetermined time.

A solid oxide fuel cell system includes a fuel cell stack that generates electric power through a reaction between a fuel gas and an oxidizing gas; a combustor in which anode and cathode off-gases discharged from the fuel cell stack are burned by diffusion combustion; a temperature sensor that detects temperature of the anode off-gas flowing into the combustor; and a controller. When the system is in at least one of the following states during power generation, the controller instructs the system to perform a power-generation control action for preventing failed combustion reactions: the temperature of the anode off-gas, detected by the temperature sensor, is below a first predetermined temperature for a predetermined continuous period of time; the temperature of the anode off-gas decreases by not less than a predetermined second temperature range during a predetermined period of time.

A control method for fuel cell system capable of executing an idle stop operation is provided, in which operation power generation of a fuel cell is selectively stopped according to a required output of a load and cathode gas is intermittently supplied to the fuel cell during an operation stop. An upper limit value and a lower limit value of an output voltage of the fuel cell during the idle stop operation is set, the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and the lower limit value, a wet/dry state of the fuel cell is detected, a wet/dry appropriate range in which the wet/dry state of the fuel cell during the idle stop operation is appropriate is set, and it is determined whether or not the detected wet/dry state of the fuel cell is within the set wet/dry appropriate range. If the wet/dry state of the fuel cell is determined to be outside the set wet/dry appropriate range, the output voltage of the fuel cell is reset, and the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and lower limit value of the reset output voltage.

A method for evaluating voltage sensor output using a diagnostic system includes: measuring an overall fuel cell stack voltage using a stack voltage sensor; identifying a fuel cell voltage of a first end cell using a first end cell voltage sensor and a second end cell using a second end cell voltage sensor; determining if a maximum value of the overall fuel cell stack voltage, the fuel cell voltage of the first end cell or the second end cell is less than a sensor limit, and if a minimum value of the fuel cell voltages is greater than the sensor limit; performing a test to identify if the maximum value is greater than an average sensor signal value and if the average sensor signal value is greater than the minimum value; and conducting a test to identify if the minimum value is less than a first predetermined threshold.

A cathode oxygen depletion (COD) control method is provided. The method includes determining whether a COD heater operates and calculating power generation and power consumption when the COD heater operates. Additionally, the power consumption is adjusted by comparing the calculated power generation and power consumption.

An apparatus for power demand distribution in a fuel cell vehicle includes: a battery management system calculating an allowable battery power that a battery can supply; a power demand distribution controller configured to derive a vehicle demand power including a drive motor demand power required by the drive motor, and determine a value corresponding to a vehicle demand power minus the allowable battery power being scaled down or the drive motor demand power, as a fuel cell demand output; and a fuel cell controller configured to drive the air compressor feeding the air to the fuel cell to enable a fuel cell to generate the fuel cell demand output calculated by the power demand distribution controller.

A method for operating a fuel cell power plant is provided to deliver power and/or receive power from a load. The fuel cell power plant includes an energy storage system connected in parallel with a fuel cell system. The method for operating includes the steps of calculating and actively proportioning a current split between the fuel cell system and the energy storage system, and controlling the proportioning using fuel cell system air flow. In one embodiment, set point changes in the fuel cell system air flow are operationally independent from a fuel cell water management system that removes product water, humidifies inlet reactant gas, and/or cools the fuel cell stack. In another embodiment, the step of calculating the current split proportion includes the selection of points on a family of V/I curves within a range from 40% fuel cell air utilization to 99% fuel cell air utilization.

A system for reducing overdraw of power in a vehicle includes a power source having a battery and a fuel cell circuit. The system further includes an ECU that transmits a power limit signal to a vehicle controller, the power limit signal corresponding to an instantaneous maximum amount of power of the power source. The ECU also determines a battery allowed power corresponding to an amount of power available to be drawn from the battery to cause the SOC of the battery to remain above a lower SOC threshold. The ECU also determines a current battery power draw from the battery corresponding to an instantaneous amount of power being drawn from the battery. The ECU is designed to reduce the instantaneous maximum amount of power in the power limit signal when the current battery power draw is greater than the battery allowed power, reducing the current battery power draw.