A method of shutting down a fuel cell system includes a fuel cell includes generating power via an electrochemical reaction between a fuel gas and an oxidant gas. A shutdown command is output to the fuel cell to stop generating power. The fuel cell is controlled to continue generating power during an oxygen consumption process to consume oxygen in the oxidant gas remaining in a cathode system of the fuel cell even when the shutdown command is output to the fuel cell. At least one of voltage, current, and power output from the fuel cell is detected during the oxygen consumption process. Whether an abnormality occurs during the oxygen consumption process is determined based on at least one of the voltage, the current, and the power. The fuel cell is controlled to stop generating power during the oxygen consumption process when it is determined that abnormality occurs.

Disclosed is a power control system and method of a fuel cell including a fuel cell that generates electricity; a load device that is electrically connected to the fuel cell; a DC/DC converter that is disposed between the fuel cell and the load device, and converts power between a low side of the DC/DC converter electrically connected to the fuel cell and a high side of the DC/DC converter electrically connected to the load device; a battery that is electrically connected to the high side of the DC/DC converter in parallel with the load device; and a controller that monitors a voltage of the high side of the DC/DC converter or a voltage of the low side of the DC/DC converter, and controls output power of the fuel cell or power consumption of the load device based on the monitored voltage of the high side or the monitored voltage of the low side.

The invention relates to a method for switching off a fuel cell system (100) having a fuel cell stack (10), that has anode chambers (13) and cathode chambers (12), and a cathode supply (20) having a cathode supply path (21) for supplying an oxygenated cathode operating gas into the cathode chambers (12), a compressor (23) arranged in the cathode supply path(21) and a cathode exhaust path (22) for discharging a cathode exhaust gas from the cathode chambers (12).

The method comprises the steps of:

(a) Maintenance of the cathode chambers (12) under excess pressure while preventing a flow of cathode operating gas through the cathode chambers (12) while keeping the cathode operating gas that is present in the cathode chambers (12) oxygen-depleted;

(b) Expansion of the oxygen-depleted cathode operating gas present in the cathode chambers (12) via the cathode supply path (31) [sic] and/or the cathode exhaust path (22), and

(c) Separation of the cathode chambers (12) from the environment.

The present disclosure generally relates to systems and methods for purging water or gas from a fuel cell system. The fuel cell system may include a multi-phase valve system and/or a separate valve system. The opening and closing of the valve systems for removing gas and water is controlled by a controller,

A fuel cell system includes a first fuel cell having first unit cells stacked together, a second fuel cell having second unit cells stacked together, a first voltage detector, a second voltage detector, and a controller. The first voltage detector detects voltage of the first unit cells for every “N” unit cells on average, and the second voltage detector detects voltage of the whole second fuel cell, or detects voltage of the second unit cells for every “M” unit cells on average. The controller determines whether any of the first unit cells is in a fuel deficiency state, by referring to a detection result of the first voltage detector, and performs a cancellation process to cancel the fuel deficiency state, on the first fuel cell that is in a power generating state, while stopping power generation of the second fuel cell, when an affirmative decision is obtained.

A pinhole determination method for a fuel cell includes steps of: blocking air supply to a fuel cell stack by a controller; measuring a cell voltage value of each of unit fuel cells of the fuel cell stack; and determining whether or not a pinhole is present by comparing the cell voltage value with an average cell voltage value.

A coolant injection controller for a fuel cell system, the coolant injection controller configured to actively control the flow of a coolant to a fuel cell assembly for cooling and/or hydrating the fuel cell assembly in response to a measure of fuel cell assembly performance, wherein the coolant injection controller is configured to provide for a first mode of operation if the measure of fuel cell assembly performance is below a predetermined threshold and a second mode of operation if the measure of fuel cell assembly performance is above the predetermined threshold, the first and second modes having different coolant injection profiles and wherein, in the first mode of operation, the coolant injection profile provides for control of the flow of coolant by alternating between at least two different injection flow rates.

There is provided a control method of a flow regulating valve of an oxidizing gas in a fuel cell. In a load disconnected state that the fuel cell is electrically disconnected from a load, the control method gradually opens the flow regulating valve that is configured to supply the oxidizing gas to a cathode of the fuel cell by a predetermined valve opening each time from a full-close position or gradually closes the flow regulating valve by a predetermined valve opening each time from a full-open position, so as to gradually change a supply amount of the oxidizing gas introduced to the cathode and cause hydrogen transmitted from an anode to the cathode in the fuel cell to be oxidized. The control method measures an open circuit voltage of the fuel cell accompanied with oxidation of the hydrogen and stores at least one valve-opening position among valve-opening positions of the flow regulating valve at a predetermined number of timings including a timing when the measured voltage shifts to an increase or shifts to a decrease, as a regulation reference valve-opening timing.

An apparatus and a method for controlling a fuel cell stack are provided to improve the performance (output) of the fuel cell stack that has suffered from deterioration. The performance is improved by adjusting a stoichiometric ratio (SR) of air supplied to the fuel cell stack and an operating temperature of the fuel cell stack based on the basis of an open-circuit decay time (ODT) indicating a time taken for a cell voltage to be reduced from a reference voltage to a threshold voltage when the supply of air to the fuel cell stack is cut off.

A method and system for controlling air flow is arranged to reduce power consumption of an air blower or an air compressor by controlling air flow, enhance stack performance by preventing stack dry-out that is more likely to occur in a low-flow range, and improve durability of the stack by decreasing frequency of exposure to high voltages.