Implementation of an engine controller unit's non-volatile memory for measuring the time of a fuel cell system in a shut-off or standby state
View Patent ↗A method for providing an accurate time that a fuel cell system has been shut-down so that the gas constituents in the anode and cathode side of the fuel cell stack can be known for an efficient next system start-up sequence. The method uses two timers, a stand-by timer that provides a time count for how long the fuel cell system has been off, but the vehicle ignition is still on, and a shut-off timer that provides a time count of how long the vehicle ignition has been off. The two time counts are added to give a complete time count of how long the fuel cell stack has been shut-down.
1. A method for determining how long a fuel cell system has not delivered hydrogen to an anode side of a fuel cell stack after a system shut-down, said method comprising:
determining whether the system has been shut-down;
incrementing a stand-by time if the system has been shut-down and a key is in a vehicle ignition;
incrementing a shut-off off time if the system has been shut-down and the key is out of the vehicle ignition;
determining whether the ignition has been turned on after a previous ignition off event;
adding the stand-by time and the shut-off time to provide an off-time that can be used to determine the gas constituency in the anode side of the stack; and
determining whether dilution air is being provided from a compressor to dilute anode exhaust.
2. The method according to claim 1 further comprising determining whether a fuel cell system battery has lost power when the ignition is off.
3. The method according to claim 2 further comprising setting the stand-by time to zero if the fuel cell system battery has lost power.
4. The method according to claim 1 further comprising setting the stand-by time to zero if the dilution air is being provided.
5. The method according to claim 1 wherein the fuel cell stack includes a first split stack and a second split stack that operate under anode flow-shifting.
6. The method according to claim 1 wherein the system shut-down includes sealing the cathode and anode side of the fuel cell stack.
7. The method according to claim 1 wherein the off-time is used to determine a proper start-up sequence of the fuel cell system.
8. A method for determining how long a fuel cell system in a vehicle has been shut-down, said method comprising:
incrementing a stand-by time if the system has been shut-down, but a key is in a vehicle ignition in an on or accessory position;
incrementing a shut-off off time if the system has been shut-down and the key is out of the vehicle ignition;
adding the stand-by time and the shut-off time to provide a total system off-time;
determining whether dilution air is being provided from a compressor to dilute anode exhaust; and
setting the stand-by time to zero if the dilution air is being provided.
9. The method according to claim 8 further comprising determining whether a fuel cell system battery has lost power when the ignition is off.
10. The method according to claim 9 further comprising setting the stand-by time to zero if the fuel cell system battery has lost power.
11. The method according to claim 8 wherein the fuel cell stack includes a first split stack and a second split stack that operate under anode flow-shifting.
12. The method according to claim 8 wherein the system shut-down includes sealing the cathode and anode side of the fuel cell stack.
13. The method according to claim 8 wherein the total system off-time is used to determine a proper start-up sequence of the fuel cell system.
14. A method for determining how long split fuel cell stacks in a fuel cell system on a vehicle have been shut-down, said method comprising:
incrementing a stand-by time if the split stacks have been shut-down, but a key is in a vehicle ignition and is in an on or accessory position;
incrementing a shut-off off time if the split stacks have been shut-down and the key is out of the vehicle ignition;
determining whether the ignition has been turned on after a previous ignition off event; and
adding the stand-by time and the shut-off time to provide an off-time that can be used to determine the gas constituency in the anode side of the stack and determine a proper start-up sequence of the fuel cell system.
15. The method according to claim 14 further comprising determining whether a fuel cell system battery has lost power when the ignition is off.
16. The method according to claim 15 further comprising setting the stand-by time to zero if the fuel cell system battery has lost power.