Method and apparatus for diagnosing fault within fuel cell stack

• US 9,373,860 B2
• Filed: 12/11/2013
• Issued: 06/21/2016
• Est. Priority Date: 12/11/2012
• Status: Active Grant

• Current Assignee: Hyundai Kefico Corporation (Hyundai Mobis Co., Ltd.), Kangnam University Industry-Academia Cooperation Foundation
• Original Assignee: Kangnam University Industry-Academia Cooperation Foundation
• Inventors: Kim, Uck Soo, Lee, Young-hyun, Jeong, Kwi Seong, Kim, Sae Hoon, Park, Hyun-Seok
• Primary Examiner(s): Grant, Robert
• Application Number:
  US14/102,693
• Publication Number:
  US 20140159738A1
• Time in Patent Office: 923 Days
• Field of Search: 324/430
• US Class Current: 1/1
• CPC Class Codes: H01M 8/04492 Humidity; Ambient humidity; Water content
• CPC Class Codes: H01M 8/04649 of fuel cell stacks
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

To diagnose a fault of a fuel cell stack, an alternating current having a first optimal frequency of a first frequency domain to diagnose a drop in cell voltage and an alternating current having a second optimal frequency of a second frequency domain to diagnose a cause of the drop in cell voltage are supplied to the fuel cell stack are provided. A distortion rate is then calculated based on voltage of the fuel cell stack according to the alternating current of the first optimal frequency, and the drop in cell voltage is diagnosed based on the calculated distortion rate. Also, impedance is calculated based on voltage and a current of the fuel cell stack according to the alternating current of the second optimal frequency and amount of water is calculated based on the calculated in the fuel cell stack, and the cause of the drop in cell voltage is diagnosed based on the calculated impedance and amount of water.

Claims

1. A method of diagnosing a fault of a fuel cell stack, the method comprising:

supplying, to the fuel cell stack, a plurality of alternating currents having different frequency combinations by an alternating current (AC) current generator;

measuring, by a processor, a distortion rate and impedance of the fuel cell stack for each alternating current, and selecting an optimal frequency based on the measured distortion rate and impedance;

supplying, to the fuel cell stack, an alternating current having the selected optimal frequency by the AC current generator;

calculating, by the processor, the distortion rate of the fuel cell stack according to the alternating current having the optimal frequency, and diagnosing a drop in cell voltage based on the calculated distortion rate; and

calculating, by the processor, the impedance of the fuel cell stack according to the alternating current having the optimal frequency, amount of water in the fuel cell stack based on the calculated impedance, and diagnosing a cause of the drop in cell voltage based on the calculated impedance and amount of water,

wherein the selecting of the optimal frequency comprises;

selecting a first frequency of an alternating current corresponding to a largest distortion rate as a first optimal frequency to diagnose the drop in cell voltage, based on the distortion rates measured for the respective alternating currents; and

selecting a second frequency of an alternating current corresponding to a largest impedance as a second optimal frequency to diagnose the cause of the drop in cell voltage, based on the impedances measured for the respective alternating currents.

2. The method of claim 1, wherein:

supplying of the plurality of alternating currents to the fuel cell stack includes supplying, to the fuel cell stack, an alternating current having a first frequency of a first frequency domain to diagnose the drop in cell voltage and an alternating current having a second frequency of a second frequency domain to diagnose the cause of the drop in cell voltage, wherein the plurality of alternating currents has the first frequency and the second frequency that are different from each other.

3. A method of diagnosing a fault of a fuel cell stack, the method comprising:

supplying, to the fuel cell stack, an alternating current having a first optimal frequency of a first frequency domain to diagnose a drop in cell voltage and an alternating current having a second optimal frequency of a second frequency domain to diagnose a cause of the drop in cell voltage by an alternating current (AC) current generator;

calculating, by a processor, a distortion rate based on voltage of the fuel cell stack according to the alternating current of the first optimal frequency, and diagnosing the drop in cell voltage based on the calculated distortion rate; and

calculating, by the processor, impedance based on the voltage and a current of the fuel cell stack according to the alternating current of the second optimal frequency and amount of water in the fuel cell stack based on the calculated impedance, and diagnosing the cause of the drop in cell voltage based on the calculated impedance and amount of water,

wherein a first frequency of an alternating current corresponding to a largest distortion rate is selected as the first optimal frequency to diagnose the drop in cell voltage, based on the distortion rate for each alternating current, and

wherein a second frequency of an alternating current corresponding to a largest impedance is selected as the second optimal frequency to diagnose the cause of the drop in cell voltage, based on impedances measure for each alternating current.

4. The method of claim 3, wherein:

diagnosing of the drop in cell voltage includes diagnosing the drop in cell voltage based on a total harmonic distortion analysis (THDA) method, and

diagnosing of the cause of the drop in cell voltage includes measuring the impedance using an electromechanical impedance spectroscopy (EIS) and diagnosing the cause of the drop in cell voltage.

5. An apparatus to diagnose a fault of a fuel cell stack, the apparatus comprising:

an alternating current (AC) injector connected to the fuel cell stack and applying an alternating current to a current which flows from the fuel cell stack to a load;

an AC current generator configured to generate the applied alternating current; and

a diagnosis processor configured to measure voltage and a current of the fuel cell stack, to diagnose a drop in cell voltage of the fuel cell stack and to diagnose a cause of the drop in cell voltage based on the measured voltage and current,

wherein an optimal frequency is selected by an optimal frequency selection processor based on measured distortion rates and impedance of the fuel cell stack for a plurality of alternating currents,

wherein the optimal frequency selection processor is configured to;

select a first frequency of an alternating current corresponding to a largest distortion rate as a first optimal frequency to diagnose the drop in cell voltage, based on distortion rates measured for the respective alternating currents; and

select a second frequency of an alternating current corresponding to a largest impedance as a second optimal frequency to diagnose the cause of the drop in cell voltage, based on impedance measured for the respective alternating currents.

6. The apparatus of claim 5, wherein:

the diagnosis processor includes;

the optimal frequency selection processor configured to select the first optimal frequency to diagnose the drop in cell voltage and the second optimal frequency to diagnose the cause of the drop in cell voltage;

an alternating current control section configured to control the AC current generator;

a distortion rate calculating section configured to measure the voltage of the fuel cell stack, and to calculate the distortion rate of the fuel cell stack based on the measured voltage;

an impedance/water calculating section configured to measure the voltage and the current of the fuel cell stack, and to calculate the impedance based on the measured voltage and current and amount of water in the fuel cell stack based on the calculated impedance; and

a diagnosis section configured to diagnose the drop in cell voltage of the fuel cell stack based on the distortion rate, and to diagnose the cause of the drop in cell voltage based on the impedance and amount of water.

7. The apparatus of claim 6, wherein:

the AC injector includes electronic devices configured to supply an alternating current according to an alternating signal output from the AC current generator.

8. A non-transitory computer readable medium containing program instructions executed by a processor, the computer readable medium comprising:

program instructions that measure a distortion rate and impedance of the fuel cell stack for each alternating current, and selecting an optimal frequency based on the measured distortion rate and impedance;

program instructions that control supply of an alternating current having the selected optimal frequency by an alternating current (AC) current generator;

program instructions that calculate the distortion rate of the fuel cell stack according to the alternating current having the optimal frequency, and diagnosing a drop in cell voltage based on the calculated distortion rate; and

program instructions that calculate the impedance of the fuel cell stack according to the alternating current having the optimal frequency, and diagnosing a cause of the drop in cell voltage based on the calculated impedance,

wherein the program instructions selecting of the optimal frequency comprises;

program instructions that select a first frequency of an alternating current corresponding to the largest distortion rate as a first optimal frequency to diagnose the drop in cell voltage, based on the distortion rates measured for the respective alternating currents; and

program instructions that select a second frequency of an alternating current corresponding to the largest impedance as a second optimal frequency to diagnose the cause of the drop in cell voltage, based on the impedance measured for the respective alternating currents.