Fuel cell system and method for voltage monitoring for a fuel cell system
View Patent ↗A fuel cell system having a redundant voltage monitoring system for monitoring the voltage which is present on a fuel cell unit, and a method for voltage monitoring.
1. A method for voltage monitoring for a fuel cell system having a fuel cell unit, with the fuel cell unit being connected via cables to an electrical component, said method comprising the steps:
detecting presence of a voltage on the electrical component;
producing, from a first voltage monitoring unit and a second voltage monitoring unit, respectively, a first actual value and a second, redundant actual value from the detected voltage which is present on the electrical component;
comparing at least one of the first actual value with a first limit value, and the second actual value with a second limit value; and
based on a result of said comparing, determining whether the first limit value or the second limit value is exceeded.
2. The method according to claim 1 , wherein the first actual value is compared with the second actual value, and a comparison value is formed.
3. The method according to claim 1 , wherein at least one of a fault signal is produced and the electrical component is switched off if the first limit value is exceeded.
4. The method according to claim 1 , wherein at least one of a fault signal is produced and the electrical component is switched off if the second limit value is exceeded.
5. The method according to claim 2 , wherein, if the comparison value exceeds a third limit value, at least one of the following is true: i) a fault signal is produced, and ii) the electrical component is switched off.
6. The method according to claim 1 , wherein at least one of the first limit value and the second limit value is equal to the no-load voltage of the fuel cell unit.
7. The method according to claim 1 , wherein the second limit value is higher than the first limit value.
8. The method according to claim 1 , wherein an additional voltage signal is produced when a voltage is present on the cables.
9. The method according to claim 8 , wherein the additional voltage signal is compared with at least one of the first and the second actual value.