Method for supplying air to a fuel cell
View Patent ↗A method for supplying air to a fuel cell ( 2 ), using a controllable air conveying device ( 7 ) which delivers an air mass flow for a cathode chamber ( 4 ) of the fuel cell ( 2 ), and using at least one air mass flow sensor ( 9, 18 ). The invention is characterized in that, for at least one location ( 19 ) in the air flow path which is situated at a distance from the at least one air mass flow sensor ( 9 ) in the flow direction, a computed estimate is made of the air mass flow present at that location.
1. A method for supplying air to a fuel cell ( 2 ), comprising delivering an air mass flow to a cathode chamber ( 4 ) of the fuel cell ( 2 ) using a controllable air conveying device ( 7 ),
providing a first air mass flow sensor ( 9 ) upstream of the controllable air conveying device ( 7 ),
providing a second air mass flow sensor ( 18 ) downstream of the controllable air conveying device ( 7 ) and upstream of the cathode chamber ( 4 ),
measuring air mass flow via the first air mass flow sensor ( 9 ) and outputting a first air mass flow value,
measuring air mass flow via the second air mass flow sensor ( 18 ) and outputting a second air mass flow measured value,
computing, independent of the second air mass flow sensor ( 18 ), an estimate of the air mass flow for the location ( 19 ) of the second air mass flow sensor ( 18 ) to provide a computed estimation, and
monitoring the function of the second air mass flow sensor ( 18 ) by means of comparison of the computed estimation and the second air mass flow sensor ( 18 ) measured value.
2. A method for supplying air to a fuel cell ( 2 ), comprising delivering an air mass flow to a cathode chamber ( 4 ) of the fuel cell ( 2 ) using a controllable air conveying device ( 7 ),
providing a first air mass flow sensor ( 9 ) upstream of the controllable air conveying device ( 7 ),
providing a second air mass flow sensor ( 18 ) downstream of the controllable air conveying device ( 7 ) and upstream of the cathode chamber ( 4 ),
measuring air mass flow via the first air mass flow sensor ( 9 ) and outputting a first air mass flow value,
measuring air mass flow via the second air mass flow sensor ( 18 ) and outputting a second air mass flow measured value,
computing, independent of the second air mass flow sensor ( 18 ), an estimate of the air mass flow for the location ( 19 ) of the second air mass flow sensor ( 18 ) to provide a computed estimation, and
monitoring the function of the second air mass flow sensor ( 18 ) by means of comparison of the computed estimation and the second air mass flow sensor ( 18 ) measured value, and
in the event that the second air mass flow sensor ( 18 ) is determined to be functional, taking into account the measured value of the second air mass flow sensor ( 18 ) as the actual variable in controlling the air mass flow, and in the event that the second air mass flow sensor ( 18 ) is determined to be non-functional, taking into account the value of the computed estimation as the actual variable in controlling the air mass flow.
3. A method for supplying air to a fuel cell ( 2 ), comprising delivering an air mass flow to a cathode chamber ( 4 ) of the fuel cell ( 2 ) using a controllable air conveying device ( 7 ),
providing a first air mass flow sensor ( 9 ) upstream of the controllable air conveying device ( 7 ),
providing a second air mass flow sensor ( 18 ) downstream of the controllable air conveying device ( 7 ) and upstream of the cathode chamber ( 4 ),
measuring air mass flow via the first air mass flow sensor ( 9 ) and outputting a first air mass flow value,
measuring air mass flow via the second air mass flow sensor ( 18 ) and outputting a second air mass flow measured value,
computing, independent of the second air mass flow sensor ( 18 ), an estimate of the air mass flow for the location ( 19 ) of the second air mass flow sensor ( 18 ) to provide a computed estimation, and
monitoring the function of the second air mass flow sensor ( 18 ) by means of comparison of the computed estimation and the second air mass flow sensor ( 18 ) measured value, and
in the event that the second air mass flow sensor ( 18 ) is determined to be non-functional, the monitoring indicates a defective second air mass flow sensor, the computed estimation is taken into account as the actual variable in controlling the air mass flow.
4. The method according to claim 1 , wherein the computed estimation is made on the basis of models and/or characteristic maps.
5. The method according to claim 1 , wherein at least one of the following variables is included in the computed estimation:
Rotational speed (N) and/or power consumption of the air conveying device ( 7 );
Pressure (P) and/or temperature (T) at one or more locations in the air flow path;
Position (Y) of a valve unit in the air flow path;
Position of a valve unit ( 14 ) in a system bypass ( 13 );
Ambient temperature;
Temperature of the fuel cell ( 2 );
Composition of the air mass flow;
Operating state and/or instantaneous electrical power of the fuel cell ( 2 );
Moisture in the feed air; and/or
Losses via leaks in the air flow path.
6. The method according to claim 1 , wherein air is supplied to a fuel cell ( 2 ) in a fuel cell system ( 1 ) which delivers electrical power for a vehicle ( 5 ).
7. The method according to claim 1 , wherein air is supplied to a fuel cell ( 2 ) in a fuel cell system ( 1 ) which delivers electrical drive power which is used at least in part as drive power for a vehicle ( 5 ).