Method and apparatus for determining humidity states of individual cells in a fuel cell, method and apparatus for controlling humidity states of individual cells in a fuel cell, and a fuel cell system

An apparatus for controlling humidity states of a plurality of cells stacked in a fuel cell,

• the apparatus comprising a controller programmed to determine that the plurality of cells presents a mixture of dry and overly humid states when:
• a minimum voltage value of at least one of the plurality of cells is equal to or less than a predetermined voltage threshold value indicative of an overly humid state, and
• at least one of the following conditions 1 through 3 is satisfied:
• condition 1:
• at least two of the plurality of cells that do not have a voltage equal to or less than a predetermined voltage threshold value indicative of an overly humid state have a voltage deviation greater than a predetermined voltage deviation threshold value,
• condition 2:
• electricity generated by and output from the fuel cell is equal to or less than a predetermined electricity generation threshold value, and
• condition 3:
• an electric current adjacent to an air inlet on a cathode side of at least one of the plurality of cells is equal to or less than a predetermined electric current threshold value;
• wherein if it is determined that the plurality of cells presents the mixture of dry and overly humid states:
• perform humidifying control to cause the plurality of the cell to attain an overly humid state, and
• perform drying control to dry the plurality of cells, to thereby cause the plurality of cells to be recovered to a predetermined humidity state.