Patent ID: 11881603
Assignee: SUBARU CORPORATION
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 8:
9. A method of estimating humidity in air exhausted from a fuel cell in a fuel cell system, the fuel cell including a cathode electrode and a hydrogen electrode opposed to the cathode electrode with a solid polymer electrolyte membrane in between, the method comprising:
acquiring, via a first sensor arranged at an inlet of the fuel cell in an air supply path supplying air to the cathode electrode of the fuel cell, a first mass flow rate of the air supplied to the cathode electrode on an intake side of the fuel cell;
acquiring, via a second sensor arranged at an outlet of the fuel cell in the air supply path exhausting air from the fuel cell, a second mass flow rate of the air exhausted, passing through the cathode electrode, from the fuel cell;
acquiring, via a third sensor arranged at the inlet of the fuel cell in the air supply path, a first humidity of air supplied into the inlet of the fuel cell in the air supply path at the first mass flow rate; and
calculating a second humidity of air in the air supply path downstream of the solid polymer electrolyte membrane by:
calculating a first difference that is mass other than moisture, included in air into the inlet of the fuel cell in the air supply by using a difference between the first mass flow rate after deducting amount of moisture on a basis of the first humidity and oxygen consumption calculated by using current, detected by an ammeter coupled with the controller, generated by the fuel cell,
calculating a second difference that is mass of water vapor included in air exhausted from the outlet of the fuel in the air supply path by using a difference between the second mass flow rate and the first difference, and
calculating the second humidity that is a ratio of the second difference to an amount of saturated water vapor corresponding to temperature at the outlet of the fuel cell in the air supply path,

wherein the humidity of air in the inlet of the fuel cell in an air supply path is controlled in response to the calculated humidity of air in the air supply path downstream of the solid polymer electrolyte membrane,
wherein the controller is configured to, in a case where the second humidity of air in the air supply path downstream of the solid polymer electrolyte membrane is low, perform humidification control to humidify air in the inlet of the fuel cell in an air supply path, and
wherein the controller is configured to, in a case where the second humidity of air in the air supply path downstream of the solid polymer electrolyte membrane is high, perform drying control to dry air in the inlet of the fuel cell in an air supply path.