Method for diagnosing fault of fuel cell stack
Disclosed herein is a method for diagnosing a fault of a fuel cell stack, including: applying a summed current obtained by summing currents of different frequency regions to the fuel cell stack; passing output voltages of the fuel cell stack through each of the different frequency filters to extract the respective diagnosis data; and diagnosing whether or not a fault has been generated in the fuel cell stack using the respective diagnosis data. Therefore, it is possible to further improve diagnosis analysis capability by applying the summed current obtained by summing the currents of the different frequency regions to the fuel cell stack and then rapidly diagnosing the fault of the fuel cell stack using the diagnosis data obtained by filtering the output voltages of the fuel cell stack.
1. A method for diagnosing a fault of a fuel cell stack performed by an apparatus for diagnosing a fault of a fuel cell stack, the method comprising:
applying a summed current obtained by summing currents of different frequency regions including a frequency used to calculate at least one of a total harmonic distortion(THD) and an impedance to the fuel cell stack;
passing output voltages of the fuel cell stack through each of different frequency filters including a high pass filter and a band pass filter to extract simultaneously the respective diagnosis data by passing the output voltages of the fuel cell stack through the high pass filter to extract a basic wave frequency to a harmonic frequency for calculating the total harmonic distortion and passing the output voltages of the fuel cell stack through the band pass filter to extract a specific frequency for calculating the impedance; and
diagnosing whether or not the fault and wetting state of the fuel cell stack have been generated in the fuel cell stack using the respective diagnosis data.
2. The method of claim 1 , wherein the diagnosing of whether or not the fault and wetting state of the fuel cell stack has been generated in the fuel cell stack using the respective diagnosis data includes diagnosing whether or not the fault has been generated in the fuel cell stack depending on a ratio of the harmonic frequency to the basic wave frequency extracted by the high pass filter.
3. The method of claim 2 , wherein the diagnosing of whether or not the fault and wetting state of the fuel cell stack has been generated in the fuel cell stack using the respective diagnosis data includes diagnosing that the fault has been generated in the fuel cell stack when the ratio of the harmonic frequency to the basic wave frequency is a specific ratio or more.
4. The method of claim 1 , wherein the diagnosing of whether or not the fault and wetting state of the fuel cell stack has been generated in the fuel cell stack using the respective diagnosis data includes diagnosing a wetting state of the fuel cell stack using an impedance for the specific frequency extracted by the band pass filter.
5. The method of claim 4 , wherein the diagnosing of whether or not the fault and wetting state of the fuel cell stack has been generated in the fuel cell stack using the respective diagnosis data includes diagnosing that an electrolyte membrane of the fuel cell stack is in a dry state when the impedance for the specific frequency is a specific impedance or more.
6. The method of claim 4 , wherein the diagnosing of whether or not the fault and wetting state of the fuel cell stack has been generated in the fuel cell stack using the respective diagnosis data includes diagnosing that an electrolyte membrane of the fuel cell stack is in a wet state when the impedance for the specific frequency is a specific impedance or less.