This document describes techniques and systems for in operando, non-invasive SOC monitoring of redox flow batteries. The described techniques and systems allow for accurate, inexpensive, portable, and real-time methods to measure the SOC of redox flow batteries. System operators can monitor the SOC by measuring an acoustic attenuation coefficient of the electrolyte in the redox flow battery. The acoustic attenuation coefficient is measured using an ultrasonic transducer attached to a probing cell, which is connected to an electrolyte flow of a redox flow battery. The acoustic attenuation coefficient provides an accurate, real-time SOC measurement that is generally insensitive to varying operational temperatures of the electrolyte solution.

A fuel cell system that supplies fuel gas and oxidant gas to a fuel cell stack and causes the fuel cell stack to generate power includes a tank that stores aqueous solution containing oxygen-containing fuel, and a reformer that reforms mixed gas obtained as the aqueous solution is vaporized, and generates the fuel gas. The fuel cell system also includes an actuator that supplies the mixed gas to the reformer, a heating device that heats the reformer, a detecting unit that estimates or detects a concentration of the oxygen-containing fuel in the mixed gas that is supplied to the reformer, and a controller programmed to control operations of the actuator and the heating device so that the fuel cell generates power. The controller is programmed to increase a thermal dose to the reformer from the heating device or reduces a supply amount of the mixed gas to the reformer by the actuator when the concentration of the oxygen-containing fuel is high, compared to when the concentration is low.

A fuel cell recovery control system and method are provided to supply hydrogen to the cathode of a fuel cell stack to remove an oxide film formed on a platinum surface of the cathode. The performance of the fuel cell stack is recovered in accordance with the oxide film removal. In addition, electric power generated during the performance recovery of the fuel cell stack is consumed in an inverter and, as such, overcharge of a battery is prevented.

The invention relates to a method to determine a content of a gas component in a gas mixture delivered recirculating through an anode chamber (12) or a cathode chamber (13) of a fuel cell (10), wherein the delivery takes place via a delivery device (26) functioning according to the positive displacement principle. The invention also relates to a fuel cell system (100) configured to execute the method. According to the invention, the content of the gas component is determined depending on geometric parameters (V, ) and operating parameters (n, U, I) of the delivery device (26), as well as on thermodynamic state variables (p, T) of the gas mixture. The sought target quantity, for example a hydrogen component of an anode gas, can thus be determined in a simple and robust manner from quantities that are already known or measured.

A power supply system comprising: power storage device (1); a fuel cell (2) connecting to the power storage device (1); an auxiliary machine (4) of the fuel cell, the auxiliary machine (4) operating in a range corresponding to a voltage across the fuel cell (2); a voltage converter (3) inserted along a first line between the fuel cell (2) and the power storage device (1). The power supply system further comprising an auxiliary machine power supplying device (5) inserted between the voltage converter (3) and the power storage device (1), the power supply device for the auxiliary machine (5) being configured to supply power from at least one of the fuel cell (2) and the power storage device (1) to the auxiliary machine (4); and a switch (6) inserted along a second line different from the first line between the fuel cell (2) and the auxiliary machine (4), the switch (6) being configured to supply power to the auxiliary machine (4).

A system for operating a fuel cell includes a controller configured to derive an output limit value of the fuel cell through an interval average value corresponding to an average of output values of the fuel cell for a designated time and a cumulative average value corresponding to an average of the output values of the fuel cell until the current point in time after starting to operate the fuel cell, and to control operation of the fuel cell based on the derived output limit value.

Disclosed are an apparatus and method for estimating a state-of-charge of a zinc flow battery by measuring a concentration of zinc ions contained in an electrolyte through an open-circuit voltage (OCV). The apparatus according to embodiments of the present invention can estimate effectively the state-of-charge of the zinc flow battery from the concentration of zinc ions measured through the OCV of the working electrode with respect to the reference electrode when the measuring electrodes are installed in the cathode electrolyte tank or the anode electrolyte tank.

An energy management method comprises a step A of outputting, by a fuel cell apparatus provided in each of a plurality of facilities, power using fuel, a step B of managing a storage amount of the fuel stored in a storage tank shared by the plurality of facilities, and a step C of allocating the storage amount of the fuel to each of the plurality of facilities.

An electrochemical cell system and a method for operating an electrochemical cell is provided. The method including determining one of a power level, current level or a voltage level of the electrochemical cell, the electrochemical cell including at least one cell having an anode side and a cathode side, the electrochemical cell further having a water transport plate operably coupled to the cathode side. An oxidant pressure level is determined in the cathode side. A water pressure level is determined in the water transport plate. The active area of the at least one cell is changed by adjusting at least one of the oxidant pressure level or the water pressure level based at least in part on the determined power level, current level or voltage level.

A fuel cell system is equipped with a fuel cell unit that is composed of a plurality of fuel cells including a first fuel cell and a second fuel cell, a first supply device and a second supply device that supply reactive gas to the first fuel cell and the second fuel cell respectively, and a control device that controls running of the first fuel cell and the second fuel cell and operation of the first supply device and the second supply device. The control device suspends electric power generation by the first fuel cell and drives the first supply device to hold an opening circuit voltage of the first fuel cell within a target range, and suspends electric power generation by the second fuel cell and stops driving the second supply device when an output P required of the fuel cell unit is equal to 0.