Fuel cell system and control method thereof

摘要

It is prevented that when a system is left unused, carried carbon ion a cathode-side catalyst to lower a power generation performance. The molar quantities of hydrogen and oxygen in a fuel gas supply/discharge system and an oxidizing gas supply/discharge system with respect to a fuel cell are calculated, and control is performed so that the molar ratio of hydrogen and oxygen which can chemically be reacted in a fuel gas and an oxidizing gas during the stop of the fuel cell is 2 or more. Hydrogen is preferably supplied in accordance with the magnitude of a cell voltage in the fuel cell so as to maintain the molar ratio. Moreover, a gas passage in the oxidizing gas supply/discharge system is preferably provided with an inlet valve and an outlet valve for sealing the oxidizing gas in the gas passage.

主权项

1. A fuel cell system which is provided with a fuel cell, and a fuel gas supply/discharge system and an oxidizing gas supply/discharge system with respect to the fuel cell, comprising:
an inlet valve provided on the side of an oxidizing gas supply path of a gas passage and an outlet valve provided on the side of an oxidizing gas discharge path for a purpose of sealing an oxidizing gas in the gas passage of the oxidizing gas supply/discharge system; a supply valve of a fuel gas provided on the side of a fuel gas supply path of the fuel gas supply/discharge system; control unit programmed to perform control so that the molar ratio of:
hydrogen included in the fuel gas of the fuel gas supply/discharge system and configured to be chemically reacted in the fuel cell andoxygen included in the oxidizing gas of the gas passage sealed by the inlet valve and the outlet valve and configured to be chemically reactedis greater than a minimum standard of 2 during the operation stop of the fuel cell so that both an anode and a cathode of the fuel cell are brought into a hydrogen atmosphere; and calculation unit programmed to calculate the molar quantities of hydrogen configured to be chemically reacted in the fuel gas supply/discharge system and oxygen configured to be chemically reacted in the oxidizing gas supply/discharge system, wherein the molar ratio based on the theoretical formula is used as a standard, wherein the calculation unit is further programmed to calculate hydrogen supply in accordance with the magnitude of a cell voltage in the fuel cell so as to maintain the molar ratio of hydrogen and oxygen as the target value at a minimum standard of more than 2, and wherein the control unit is further programmed to form a hydrogen-rich state in which hydrogen is present more abundantly than oxygen in the region where the electrochemical reaction can occur so that both an anode and a cathode of the fuel cell are brought into a hydrogen atmosphere in which oxygen is not present or is hardly present in the vicinity of both the anode and the cathode of the fuel cell, and so that abnormal potential can be suppressed while inhibiting the occurrence of the chemical reaction.