Fuel cell system and control method thereof

Patent metadata

Field	Value
Publication number	US-10388972-B2
Application number	US-201515522393-A
Country	US
Kind code	B2
Filing date	Sep 17, 2015
Priority date	Oct 28, 2014
Publication date	Aug 20, 2019
Grant date	Aug 20, 2019

Abstract

In order to improve estimation accuracy of a purging amount, a fuel cell system comprises a supply valve that controls a supply of an anode gas into an anode system, a purge valve that discharges an off-gas from the anode system, a pressure detecting unit configured to estimate or measures a pressure inside the anode system, and a purging amount estimating unit configured to estimate a purging amount of the off-gas discharged from the anode system through the purge valve based on a pressure change inside the anode system during a purge valve close duration in a supply valve open state and a pressure change inside the anode system during a purge valve close duration in a supply valve close state.

First claim

The invention claimed is:

1. A fuel cell system having a fuel cell supplied with an anode gas and a cathode gas to generate electricity from the fuel cell depending on a load, comprising:
a supply valve for supplying the anode gas into an anode system of the fuel cell system;
a purge valve for discharging an off-gas from the anode system; and
a controller programmed to estimate or measure a pressure inside the anode system,
wherein the controller is further programmed to estimate a value of a purging amount of the off-gas discharged from the anode system through the purge valve based on a pressure change inside the anode system during a purge valve close duration in a supply valve open state and a pressure change inside the anode system during the purge valve close duration in a supply valve close state.

2. The fuel cell system according to claim 1 , wherein the controller is further programmed to:
estimate a first gas amount accumulated in the anode system during the purge valve close duration based on a pressure change inside the anode system during the purge valve close duration in the supply valve open state, and
estimate a second gas amount flowing out from the anode system based on a pressure change inside the anode system during the purge valve close duration in the supply valve close state, regardless of an open/close state of the purge valve in the supply valve close state, and
the value of the purging amount is estimated based on the first gas amount and the second gas amount.

3. The fuel cell system according to claim 1 , wherein the controller is further programmed to estimate the value of the purging amount when the pressure inside the anode system in the supply valve close state decreases to an initial pressure inside the anode system in the supply valve open state.

4. The fuel cell system according to claim 2 , wherein the controller is further programmed to
estimate a gas amount remaining in the anode system based on a pressure inside the anode system during the estimation and an initial pressure when the value of the purging amount is estimated before the pressure inside the anode system in the supply valve close state decreases to the initial pressure of the anode system in the supply valve open state, and
correct the second gas amount based on the remaining gas amount.

5. The fuel cell system according to claim 1 , wherein the controller is further programmed to
open or close the purge valve based on an open/close state of the supply valve and a load of the fuel cell, and
close the purge valve in the supply valve open state.

6. The fuel cell system according to claim 5 , wherein the controller is further programmed to open the purge valve in the supply valve close state with a valve open command of the purge valve being issued by changing an interval of issuing the valve open command based on a load of the fuel cell.

7. The fuel cell system according to claim 6 , wherein the controller is further programmed to open the purge valve when a predetermined time elapses after the supply valve is closed.

8. The fuel cell system according to claim 6 , wherein the controller is further programmed to close the purge valve in the supply valve close state based on a purge valve open time.

9. The fuel cell system according to claim 6 , wherein the controller is further programmed to
determine whether or not the purging amount is insufficient based on the value of the purging amount estimated by the controller, and
reduce an interval of issuing the valve open command of the purge valve to be shorter than an interval set based on a load of the fuel cell if it is determined that the purging amount is insufficient.

10. The fuel cell system according to claim 9 , wherein the controller is further programmed to:
compute a valve open request time of the purge valve based on a load of the fuel cell,
issue the valve open command of the purge valve when an integration value of the valve open request time is equal to or longer than a first predetermined value,
subtract the purge valve open time from the integration value of the valve open request time if it is determined that the purging amount is not insufficient, and
maintain the integration value of the valve open request time as it is if it is determined the purging amount is insufficient.

11. The fuel cell system according to claim 1 , wherein the controller is further programmed to:
control an open/close state of the supply valve based on a load of the fuel cell such that a supply state in which the anode gas is supplied to the anode system by opening the supply valve and a supply stop state in which the supply of the anode gas into the anode system stops by closing the supply valve are repeated alternately, and
estimate the value of the purging amount based on a pressure change inside the anode system in the supply state and the supply stop state through a plurality of times.

12. A control method of a fuel cell system having a fuel cell supplied with an anode gas and a cathode gas to generate electricity from the fuel cell depending on a load, a supply valve for supplying the anode gas into an anode system of the fuel cell system, a purge valve for discharging an off-gas from the anode system, and a controller programmed to estimate or measure a pressure inside the anode system,
the control method comprising
estimating a value of a purging amount of the off-gas discharged from the anode system through the purge valve based on a pressure change inside the anode system during a purge valve close duration in a supply valve open state and a pressure change inside the anode system during the purge valve close duration in a supply valve close state.

Assignees

• Nissan Motor

Inventors

• Asai Yoshitomo

Classifications

• H01M8/04

  Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids · CPC title

• H01M8/0432

  Temperature; Ambient temperature · CPC title

• H01M8/04402

  of anode exhausts · CPC title

• H01M8/04761

  of fuel cell exhausts · CPC title

• H01M8/04179 Primary

  by purging or increasing flow or pressure of reactants · CPC title