KR101308254B1 - Apparatus and method for monitoring of fuel cell stack status - Google Patents

Abstract

PURPOSE: An apparatus and a method for diagnosing a fuel cell stack state are provided to increase diagnosis efficiency by diagnosing the fuel cell stack state according to whether or not the principle of superposition is valid after applying diagnosing signals to a fuel cell stack. CONSTITUTION: An apparatus for diagnosing a fuel cell stack state comprises a signal generating part (31), a signal processing part (32), and a determining part (33). The signal generating part is arranged to apply two or more diagnosing direct current signals to a fuel cell stack (10). The signal processing part measures response signals corresponding to the diagnosing direct current signals from the fuel cell stack. The determining part determines whether or not the fuel cell stack is abnormal by comparing the sum of the response signals corresponding to the diagnosing direct current signals and a response signal of a diagnosing overlap signal corresponding to the sum of the diagnosing direct current signals. [Reference numerals] (20) Load; (31) Signal generating unit; (32) Signal processing unit; (33) Determining unit

Description

Apparatus and method for diagnosing a state of a fuel cell stack {APPARATUS AND METHOD FOR MONITORING OF FUEL CELL STACK STATUS}

The present invention relates to an apparatus and method for diagnosing a state of a fuel cell stack, and more particularly, a technique for determining whether or not linearity of a response to a signal applied to a fuel cell stack is disclosed.

Currently, as the power supply for driving a vehicle, a type of polymer electrolyte membrane fuel cell (PEMFC) having the highest power density among fuel cells (PEMFC) is being studied, which is a low operating temperature. Fast start-up time and fast power conversion response time. The polymer electrolyte membrane fuel cell evenly distributes the reaction gas generated through a membrane electrode assembly (MEA) having a catalytic electrode layer having an electrochemical reaction on both sides of the solid polymer electrolyte membrane in which hydrogen ions move, and generated. Gas Diffusion Layer (GDL), which serves to transfer electrical energy, gaskets and fasteners for maintaining the tightness and proper fastening pressure of the reaction gases and cooling water, and separators for moving the reaction gases and cooling water. (Bipolar Plate) is included.

A plurality of unit cells are stacked on the unit cell, a current collector, an insulating plate, and an end plate for supporting the stacked cells are coupled to the outermost unit cell. Thereby forming a fuel cell stack. In order to obtain a potential required in an actual vehicle, unit cells must be stacked as many as required, and stacking unit cells is a stack. The electromotive force of the unit cell depends on fuel and oxygen. For example, in the case of a hydrogen fuel cell using hydrogen, the ideal output voltage is about 1.3V, so that a plurality of cells are stacked in series to produce electric power for driving a vehicle.

On the other hand, in the fuel cell vehicle, the cell voltage is used for grasping the stack performance, operation state, failure, etc., and is used for various control of the system such as flow rate control of the reaction gas. It is measured by connecting to cell voltage measuring device by lead wire.

Conventional cell voltage monitoring (CVM) directly measures the voltage of every cell or two cells in the stack, and the measurement information is integrated by the main controller (the upper controller) that collects the voltages of all the cells. In other words, it monitors the voltage drop caused by the fault result rather than the cause of the fault. However, the conventional method requires a connector corresponding to each cell because it measures the voltage of each cell, and there is a problem in configuring a device for monitoring the voltage drop.

The background technology of the present invention is described in Republic of Korea Patent Publication No. 10-1090705 (Dec. 1, 2011).

The technical problem to be achieved by the present invention is to provide a technique for diagnosing the state of the stack depending on whether the principle of superposition is established by applying a diagnostic signal to the stack and analyzing the response to diagnose the state of the fuel cell stack. To do this.

An apparatus for diagnosing a state of a fuel cell stack according to an embodiment of the present invention includes a signal generator for applying two or more diagnostic DC signals to a fuel cell stack, and measuring a response signal corresponding to the diagnostic DC signals from the stack. In the case of applying the signal processing unit and the two or more diagnostic DC signals to the stack, respectively, the response signal sum corresponding thereto and the diagnostic superimposition signal corresponding to the sum of the two or more diagnostic DC signals are applied. It includes a determination unit for comparing the corresponding response signal to determine whether the stack abnormality.

The signal generator may apply the two or more diagnostic DC signals to the stack at predetermined time intervals.

The determination unit may determine that the stack state is normal when the sum of the response signals when the two or more diagnostic DC signals are equal to the response signal to the diagnostic overlapping DC signal is different, and when the difference is different, the state of the stack. Can be determined to be abnormal.

According to another aspect of the present invention, there is provided a method for diagnosing a state of a fuel cell stack, the method for diagnosing a state of a stack state of an apparatus for diagnosing a state of a fuel cell stack, the method comprising: applying two or more diagnostic DC signals to the stack; Measuring each response signal corresponding to the diagnostic DC signal from a stack; applying a diagnostic overlapping DC signal corresponding to the sum of the two or more diagnostic DC signals to the stack; Measuring a response signal corresponding to a diagnostic superimposed direct current signal; and comparing the sum of the respective response signals measured with a response signal corresponding to the diagnostic superimposed direct current signal to determine whether there is an abnormality in the stack. .

As described above, the apparatus and method for diagnosing a state of a fuel cell stack according to an exemplary embodiment of the present invention apply a diagnostic signal to a stack and analyze its response to diagnose the state of the fuel cell stack. As a result, the state diagnosis performance of the stack can be improved by diagnosing the state of the stack.

1 is an exemplary view for explaining a connection state and configuration of a state diagnosis apparatus of a fuel cell stack according to an embodiment of the present invention;
2 is a flowchart of a method for diagnosing a state of a fuel cell stack according to FIG. 1;
3A is an exemplary diagram showing linearity among voltage-current characteristic curves applied to the fuel cell stack according to FIG. 2;
3B is an exemplary diagram illustrating nonlinearity among voltage-current characteristic curves applied to the fuel cell stack according to FIG. 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms used are terms selected in consideration of the functions in the embodiments, and the meaning of the terms may vary depending on the user, the intention or the precedent of the operator, and the like. Therefore, the meaning of the terms used in the following embodiments is defined according to the definition when specifically defined in this specification, and unless otherwise defined, it should be interpreted in a sense generally recognized by those skilled in the art.

1 is an exemplary diagram for explaining a connection state and a configuration of a state diagnosis apparatus of a fuel cell stack according to an exemplary embodiment of the present invention.

Referring to FIG. 1, the state diagnosis apparatus 30 is connected to a fuel cell stack 10 (hereinafter referred to as a 'stack') and a load 20, connected to the stack 10 to apply a diagnostic DC signal, The response signal output from the stack 10 is measured by being connected to the load 20. In detail, the state diagnosis apparatus 30 includes a signal generator 31, a signal processor 32, and a determiner 33.

The signal generator 31 applies two or more diagnostic DC signals I ₂ to the stack 10. The diagnostic DC signal I ₂ refers to a signal of a DC component applied to the stack 10 to grasp the characteristics of the response signal of the stack 10. The diagnostic DC signal I ₂ may be composed of a plurality of signals according to a user's setting, and a signal in which each of the diagnostic DC signals I ₂ is overlapped is called a diagnostic overlap signal. For example, when each of the diagnostic DC signals I ₂ is a current signal of 0.1 [A] and 0.2 [A], the diagnostic superimposition signal is 0.3 [A].

In addition, the signal generator 31 may apply two or more diagnostic DC signals I ₂ to the stack 10 at predetermined time intervals. The signal generator 31 sequentially applies a plurality of diagnostic DC signals to the stack 10. If the time difference between the diagnostic DC signals I ₂ applied is too large, a value of the response signal depends on the state of the stack 10. This may vary. Therefore, the time for which the diagnostic DC signal I ₂ is applied to the stack 10 is preferably injected within a predetermined time interval.

Basically, the stack 10 causes current to flow from the stack 10 to the load 20 by the stack signal I ₁ generated due to the stacking of cells. Therefore, the signal generator 31 operates the stack 10 by the stack signal I ₁ while the load 20 is connected to the stack 10, and the diagnostic direct current signal I ₂ to the stack 10. When the signal is added, the combined signal I is output to the load 20, and the state of the stack 10 is diagnosed through the characteristics of the response signal.

The signal processor 32 measures the response signals V and I corresponding to the diagnostic DC signal I2 from the stack 10. The signal processor 32 measures the voltage V or the current I of the entire stack 10, not the voltage or current of each cell constituting the stack 10. This can simplify the configuration of the state diagnosis device 30 by measuring the voltage V of the entire stack 10. The response signal is a response signal of a diagnostic direct current signal (I ₂₎ Voltage (V) or current (I) each of the diagnosing DC signal (I ₂₎ as a signal output corresponding to each is applied from the signal generating unit (31) (V, I) is output to the determination unit 33.

When the determination unit 33 applies two or more diagnostic DC signals I ₂ to the stack 10, the sum of the respective response signals corresponding thereto and the two or more diagnostic DC signals I ₂ is added together. When a diagnostic superimposition signal corresponding to is applied, the response signal corresponding thereto is compared to determine whether the stack 10 is abnormal. For example, if the sum of the response signals when two or more diagnostic DC signals I ₂ are applied to each other and the response signals for the diagnostic overlapping DC signals are the same, the state of the stack 10 is determined to be normal. 10) can be determined to be abnormal.

The determination unit 33 analyzes the response signal of the stack 10 to determine whether the stack 10 has linearity with respect to the diagnostic DC signal I ₂ . That is, when two or more diagnostic DC signals I ₂ are applied to each other, and the sum of the response signals corresponding thereto is the same as the response signal of the diagnostic overlap signal, when the principle of superposition is established for the stack 10, the stack ( The state of 10) is judged to be normal. However, if the principle of overlap does not hold for the stack 10, the state of the stack 10 is determined to be abnormal.

2 is a flowchart of a method of diagnosing a state of a fuel cell stack according to FIG. 1.

Hereinafter, the description of FIG. 2 will be described using the configuration of the state diagnosis apparatus 30 of the fuel cell stack 10 of FIG. 1.

Referring to FIG. 2, in the method for diagnosing a state of a fuel cell stack 10 according to an exemplary embodiment of the present invention, first, two or more diagnostic DC signals I ₂ are respectively applied to the stack 10 by the signal generator 31. (S210). In this case, the plurality of diagnostic DC signals I ₂ applied are sequentially applied, and the applied time interval may be set differently by the user's setting.

Next, the signal processor 32 measures the response signals V and I corresponding to the diagnostic DC signal I ₂ from the stack 10 (S220). The response signals V and I to be measured are voltage V or current I signals for the entire stack 10, and the response signals V and I are output to the determination unit 33.

Next, the signal generator 31 applies a diagnostic superimposed DC signal corresponding to the sum of two or more diagnostic DC signals I ₂ to the stack 10 (S230). For example, in the case of applying a diagnostic DC signal of 0.1 [A] and 0.2 [A] to the stack 10 in step S210, 0.3 [A] is applied to the stack 10 as a diagnostic superimposition signal.

Next, the signal processor 32 measures response signals V and I corresponding to the diagnostic superimposed DC signal I ₂ from the stack 10 (S240). The response signals V and I to be measured are voltage V or current I signals for the entire stack 10, and the response signals V and I are output to the determination unit 33.

The diagnostic DC signal I ₂ is applied to the stack 10 from step S210 to step S240, and the response signals V and I are measured therefrom.

Next, the determination unit 33 compares the measured sum of each response signal and the response signal corresponding to the diagnostic superimposed DC signal to determine whether the stack 10 is abnormal (S250).

3A is an exemplary view showing linearity among voltage-current characteristic curves applied to the fuel cell stack according to FIG. 2, and FIG. 3B is an illustration showing nonlinearity among voltage-current characteristic curves applied to the fuel cell stack according to FIG. 2. It is also.

In the case of FIG. 3A, the voltage-current characteristic curve may be expressed as V = −2.498 * I + 41.26 [V]. In this case, assuming that the stack signal is set to 1 [A], the voltage as the response signal is 38.7620 [V]. For example, when the diagnostic DC signals are 0.1 [A] and 0.2 [A], 1.1 [A] and 1.2 [A] are applied to the stack 10 in combination with 1 [A], which is a stack signal, respectively. Are 38.5122 [V] and 38.2624 [V], respectively.

In addition, the diagnostic superimposition signal is 0.3 [A], which is the sum of 0.1 [A] and 0.2 [A], and 1.3 [A], which is the sum of the stack signal 1 [A], is applied to the stack, and the response signal is 38.0126 [V]. do. When the diagnostic DC signal is 0.1 [A] or 0.2 [A], the sum of the response signals is 38.5122 [V] + 38.2624 [V] = 76.7746 [V], and the response when the diagnostic overlap signal is 0.3 [A]. Since the signal is 38.0126 [V] and the response signal according to the stack signal is 38.7620 [V], it is 38.0126 [V] + 38.7620 [V] = 76.7746 [V]. As a result, since the sum of the response signals corresponding to the plurality of diagnostic DC signals and the response signals corresponding to the diagnostic superimposition signals have the same value, the stack state can be determined to be a normal state because the principle of superposition is established and has linearity. Can be.

In the case of FIG. 3B, the voltage-current characteristic curve may be expressed as V = -0.067 * I3 + 0.6943I2-3.992I + 41.33 [V]. In this case, assuming that the stack signal is set to 1 [A], the response signal voltage is 37.9653 [V]. For example, if the diagnostic DC signal is 0.1 [A] and 0.2 [A], 1.1 [A] and 1.2 [A] are applied to the stack in combination with 1 [A], which is the stack signal, respectively, and the response signal is 37.6897, respectively. [V], 37.4236 [V].

In addition, the diagnostic superimposition signal is 0.3 [A], which is the sum of 0.1 [A] and 0.2 [A], and 1.3 [A] which is combined with the stack signal of 1 [A] is applied to the stack, and the response signal is 37.1666 [V]. do. When the diagnostic DC signal is 0.1 [A] or 0.2 [A], the sum of the response signals is 37.6897 [V] + 37.4236 [V] = 75.1133 [V], and the response when the diagnostic superimposition signal is 0.3 [A]. Since the signal is 37.1666 [V] and the response signal according to the stack signal is 37.9653 [V], 37.1666 [V] + 37.9653 [V] = 75.1319 [V]. As a result, since each response signal sum corresponding to the plurality of diagnostic DC signals and the response signal corresponding to the diagnostic superimposition signal have different values, the state of the stack is in an abnormal state because the principle of superposition does not hold and thus has nonlinearity. You can judge.

As described above, the apparatus and method for diagnosing a state of a fuel cell stack according to an exemplary embodiment of the present invention apply a diagnostic signal to a stack and analyze its response to diagnose the state of the fuel cell stack. Therefore, by diagnosing the state of the stack, it is possible to improve the state diagnosis performance of the stack.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, Therefore, the present invention should be construed as a description of the claims which are intended to cover obvious variations that can be derived from the described embodiments.

10: fuel cell stack
20: load
30: status diagnosis device
31: signal generator
32: signal processing unit
33: judgment unit

Claims (6)

A signal generator for applying two or more diagnostic DC signals to the fuel cell stack;
A signal processor which measures a response signal corresponding to the diagnostic DC signal from the stack; And
When the two or more diagnostic DC signals are applied to the stack, the respective response signals sum corresponding thereto, and when the overlapping diagnostic signals corresponding to the sum of the two or more diagnostic DC signals are applied, the response corresponding thereto. And a determination unit which compares signals to determine whether there is an abnormality in the stack. The method of claim 1,
The signal generator,
And an apparatus for diagnosing a state of a fuel cell stack applying the two or more diagnostic DC signals to the stack at predetermined time intervals. The method of claim 1,
The determination unit,
When the sum of the response signals when the two or more diagnostic DC signals are applied to each other and the response signal to the diagnostic superimposed DC signal are the same, the state of the stack is determined to be normal; Health diagnostic device for the battery stack. In the stack state diagnosis method of the fuel cell stack state diagnosis device,
Applying two or more diagnostic DC signals to the stack, respectively;
Measuring each response signal corresponding to the diagnostic DC signal from the stack;
Applying a diagnostic overlapping DC signal corresponding to the sum of the two or more diagnostic DC signals to the stack;
Measuring a response signal corresponding to the diagnostic overlapping DC signal from the stack; And
And comparing the measured sums of the response signals with the response signals corresponding to the diagnostic overlapping DC signals to determine whether there is an abnormality in the stack. 5. The method of claim 4,
The step of applying the diagnostic DC signal,
And applying the two or more diagnostic DC signals to the stack at predetermined time intervals. 5. The method of claim 4,
Determining the abnormality of the stack,
When the sum of the response signals when the two or more diagnostic DC signals are applied to each other and the response signal to the diagnostic superimposed DC signal are the same, the state of the stack is determined to be normal; How to diagnose the condition of the battery stack.

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