KR101879647B1 - Management system for fuel cell - Google Patents

Abstract

The present invention can accurately and easily predict factors such as the replacement timing of the fuel cell stack, the occurrence of a failure, and the possibility of a failure by using the indicator measured from the fuel cell stack to grasp the state of the fuel cell stack, And more particularly to a fuel cell management system for improving utilization efficiency.
The fuel cell management system according to the present invention includes a fuel cell stack having a plurality of fuel cell cells that receive fuel containing hydrogen and produce electric power, and a fuel cell stack connected to the fuel cell stack, A fuel cell comprising: A detector configured to correspond to the fuel cell stack and measuring at least one of voltage, current, and temperature of the fuel cell stack; And controlling the connection between the detection unit and the fuel cell stack to measure the indicator, calculating a characteristic value of the fuel cell stack using the indicator measured by the detection unit, comparing the measured characteristic value with a previously stored reference characteristic value, And a controller for converting the characteristic value into a comparative characteristic value that can be compared with the reference characteristic value in order to analyze the state of the fuel cell stack.

Description

[0001] MANAGEMENT SYSTEM FOR FUEL CELL [0002]

The present invention relates to a fuel cell management system, and more particularly, to an apparatus and a method for monitoring a state of a fuel cell stack using an indicator measured from a fuel cell stack, The present invention relates to a fuel cell management system for improving fuel cell utilization efficiency.

Fuel cells are attracting attention as an energy source that can generate electricity and heat energy by replacing other energy sources. 2. Description of the Related Art In recent years, a fuel cell has been used as a small-sized self-power generation facility or as a power source of a moving object such as a vehicle in order to solve a power shortage due to an abrupt increase in electric power consumption.

Such a fuel cell is advantageous in that when a material capable of extracting hydrogen or hydrogen is injected as a raw material, heat and electricity are produced by hydrogen and oxygen reaction, and water is discharged to prevent air pollution. Particularly, when the fuel cell can continuously supply only fuel, it is easy to miniaturize, and the desired power generation capacity can be increased or decreased.

However, since the fuel cell has different characteristics from those of the existing battery, engine, and renewable energy generation apparatuses, and thus requires different management methods, there is no way to efficiently manage the fuel cell, It is true.

In particular, the output voltage of the fuel cell varies greatly due to various factors such as the internal resistance, the temperature, the purity of hydrogen contained in the fuel, and the supply pressure of the fuel, or breakage occurs. Therefore, a management method that accurately grasps the characteristics and conditions of the fuel cell stack is required for stable operation of the fuel cell while maintaining a high output.

Korean Registered Patent No. 10-1382260 (Registration date April 04, 2014)

Accordingly, an object of the present invention is to accurately and easily predict factors such as a replacement timing of a fuel cell stack, a failure occurrence, and a possibility of a failure by grasping the state of the fuel cell stack using an indicator measured from the fuel cell stack Thereby improving the fuel cell utilization efficiency.

In order to achieve the above object, a fuel cell management system according to the present invention includes: a fuel cell stack having a plurality of fuel cell units that receive fuel containing hydrogen and produce electric power; A converter for converting a voltage output from the fuel cell; A detector configured to correspond to the fuel cell stack and measuring at least one of voltage, current, and temperature of the fuel cell stack; And controlling the connection between the detection unit and the fuel cell stack to measure the indicator, calculating a characteristic value of the fuel cell stack using the indicator measured by the detection unit, comparing the measured characteristic value with a previously stored reference characteristic value, And a controller for converting the characteristic value into a comparative characteristic value that can be compared with the reference characteristic value in order to analyze the state of the fuel cell stack.

The reference characteristic value or the characteristic value or the comparison characteristic value of the fuel cell stack may be expressed by a graph or an equation by a magnitude of an output voltage or a variation of an output voltage according to an output current of the fuel cell stack or the fuel cell cell , A magnitude of an output voltage corresponding to a predetermined output current value or a variation value of the output voltage.

Wherein the reference characteristic value is obtained by calculating a variation value of an output voltage or an output voltage corresponding to the output current for one fuel cell cell and the characteristic value of the fuel cell stack is a characteristic value per fuel cell cell Converted value.

Wherein the detection unit comprises: a test load connected to the fuel cell stack; A switch for connecting or disconnecting the test load and the fuel cell stack; A voltmeter for measuring an open circuit voltage of the fuel cell stack or a terminal voltage of the test load, and a thermometer for measuring the temperature of the fuel cell stack.

And the reference characteristic value includes a reference value for determining the state of the fuel cell stack.

The control unit may control the output voltage according to the magnitude of the output voltage based on the comparison characteristic value and the magnitude of the output voltage based on the reference characteristic value or the variation value of the output voltage based on the comparison characteristic value, The state of the fuel cell stack is analyzed by determining whether a variation value of the output voltage is within a range defined by the reference value.

Wherein the control unit calculates an internal resistance of the fuel cell stack using a value measured by the detection unit, calculates a constant determined by the internal degradation, and the variation value of the output voltage or the output voltage is the output current Is divided by the current applied to the test load, and is multiplied by the constant.

The fuel cell management system according to the present invention grasps the state of the fuel cell stack by using the indicator measured from the fuel cell stack, thereby accurately and easily detecting the replacement timing of the fuel cell stack, the occurrence of a failure, It is possible to improve the fuel cell utilization efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a configuration of a fuel cell management system according to the present invention; FIG.
2 is a block diagram for explaining the fuel cell characteristic detection and management method according to the present invention.
3 is an exemplary diagram showing an example of a cell voltage graph according to a current density.
4 is an exemplary view showing an example of a cell voltage graph according to the current density according to the fuel cell stack temperature.
5 is a flowchart for explaining a state analysis process of the fuel cell stack.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be noted that the drawings denoted by the same reference numerals in the drawings denote the same reference numerals whenever possible, in other drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. And certain features shown in the drawings are to be enlarged or reduced or simplified for ease of explanation, and the drawings and their components are not necessarily drawn to scale. However, those skilled in the art will readily understand these details.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a configuration diagram briefly showing a configuration of a fuel cell management system according to the present invention; FIG.

1, a fuel cell management system according to the present invention includes a battery 10, a fuel cell unit 20, a detection unit 22, and a control unit 80, A load 90 may be connected to the battery 10.

The battery 10 receives and supplies external power or power output from the fuel cell unit 20 and supplies the charged power under the control of the control unit 80 when the load 90 is connected. To this end, the battery 10 may be configured to include a circuit for charge / discharge and connection of a load. The battery 10 is composed of a battery that can be charged and discharged, such as a lead acid battery or a metal oxide battery. Here, the battery 10 may be composed of a different power source, for example, a solar cell, a wind power generator, a hydroelectric power generator, or any other type or type of fuel cell, In the present invention, the fuel cell unit 20 and the battery 10 are connected in parallel, and therefore, the present invention is not limited thereto.

The fuel cell unit 20 is activated under the control of the control unit 80 to produce electric power and supplies the produced electric power to the load 90 or the battery 10 via the DC converter 26. [ The fuel cell unit 20 includes a supply device for supplying hydrogen or a fuel capable of extracting hydrogen to the fuel cell stack and a recirculating device for recycling the used fuel to use the residual hydrogen contained in the used fuel 22). In addition, the fuel cell stack may include a membrane electrode assembly (MEA), but may be a fuel cell having other types of electrodes, and the present invention is not limited by the presented examples. The detailed structure and operation principle of such a fuel cell are disclosed in detail, and a detailed description thereof will be omitted.

DC converter 26 boosts or reduces the voltage of the electric power produced from the fuel cell 21 and transfers it to the external circuit or battery 10. [ In addition, the DC converter 26 regulates the current output from the fuel cell 21 under the control of the controller 80. This DC converter 26 can be implemented by a buck-boost circuit and controls the switching of the buck-boost circuit by PWM (Pulse Width Modulation) 21, respectively. Here, the buck-boost circuit is merely an example and should not be construed as limiting the present invention.

The control unit 80 controls the operation of the fuel cell 21 and the DC converter 26 and measures the index of the stack S constituting the fuel cell 21 and measures the internal resistance or the test load current And compares the calculated reference characteristic value with a previously calculated reference characteristic value to analyze the output state of the fuel cell 21 to predict the occurrence of the failure of the fuel cell stack S or the necessity of detailed inspection. The controller 80 may output the analysis result or the prediction information through an output unit (not shown) or may provide the user with an analysis result or prediction information through an external device connected through the communication device. However, the present invention is not limited thereto. Here, the output unit and the communication device are omitted in the detailed description of the present invention, but they can be easily implemented. The output unit can be realized through a small liquid crystal display device and various display devices in the vehicle. The communication device can be implemented through a wired communication device such as Bluetooth, Wi-Fi, etc., and a wired communication device such as USB. It will be omitted. The control unit 80 controls the detecting unit 22 to measure a predetermined index from the fuel cell stack S and calculates a characteristic value or a cell characteristic value of the fuel cell stack S, And compares the obtained characteristic value with a previously stored reference characteristic value. This will be described in more detail with reference to the following drawings.

On the other hand, the control unit 80 may limit the output of the fuel cell according to the usage state of the fuel cell 21. [ Specifically, the control unit 80 compares the voltage drop in accordance with the output current of the fuel cell 21 at the current operating temperature of the fuel cell 21 with the voltage drop calculated in advance, , Limit output, and output stop. These steps are not intended to limit the invention by the three steps presented as being capable of further increasing as needed.

More specifically, the control unit 80 controls the DC converter 26 to maintain a normal output when a normal voltage drop in accordance with the main operation temperature only occurs in the use state of the fuel cell 21. The DC converter 926 controls the DC converter 926 to limit the output current when the instantaneous voltage drop is greater than a predetermined first rate in a state where the voltage drop is greater than a normal voltage drop, The fuel cell 21 is disconnected from the load in order to protect the fuel cell 21.

FIG. 2 is a block diagram for explaining a fuel cell characteristic detection and management method according to the present invention, and FIG. 3 is an exemplary view showing an example of a cell voltage graph according to current density. 4 is an exemplary diagram showing an example of a cell voltage graph according to the current density for each fuel cell stack temperature.

2 to 4, the fuel cell management system according to the present invention measures an indicator indicative of the characteristics of the fuel cell stack and calculates the current state of the fuel cell stack S according to a predetermined calculation method And the fuel cell management can be efficiently performed by performing analysis such as normal operation, failure occurrence, and life prediction.

2, the fuel cell management system detects the characteristics of the fuel cell stack S and performs a state analysis of the entire stack S or the cells C: C1 to Cn constituting the stack S . More specifically, the fuel cell 21 of the fuel cell unit 20 forms a single fuel cell stack S by connecting a plurality of cells C in series to obtain a constant output voltage and power. If necessary, a plurality of such fuel cell stacks (S) are provided to secure an output capacity suitable for the purpose of use. For this fuel cell 21, the fuel cell management system is constituted by a detection section 22 for detecting characteristics of the stack S, with respect to at least one fuel cell stack S constituting the fuel cell 21. Specifically, the detection unit 22 is connected in parallel between the fuel cell stack S and the output end of the fuel cell stack S. The detecting section 22 may be composed of a plurality of fuel cell stacks S and may be connected to each fuel cell stack S when the plurality of fuel cell stacks S are constituted. Or one detecting part 22 may be selectively connected to the plurality of fuel cell stacks S to detect the characteristics of the connected fuel cell stacks S, 80).

The detection unit 22 measures the open circuit voltage (OCV), the load current, and the load voltage, which are initial voltages of the fuel cell stack S, under the control of the control unit 80. Particularly, the load current and the load voltage that can be checked by the control unit 80 through the detection unit 22 can be determined by using a test load R1 configured by using a resistive element such as a test load R1 having a predetermined resistance value, And the detecting section 22 may be configured to include the test load R1 and the switch S1 for connecting the test load R1 and the fuel cell stack S, The test load R1 and the switch S1 may be connected in series. The detection unit 22 detects the operation of the switch S1 with the fuel cell stack S and the test load 90 in the open circuit state in which the fuel cell stack S is not connected to the load 90 or the battery 10 As shown in FIG.

Although not shown in the drawings, the detection unit 22 is provided with a voltmeter for measuring the terminal voltage, the test load voltage, or the current of each fuel cell stack S, the ammeter, and the temperature of the fuel cell stack S A thermometer can be included. Here, the voltmeter, the ammeter, or the thermometer may not be provided for each fuel cell stack S but may be shared and selectively connected to the fuel cell stack S and the detecting unit 22, It is not.

The control unit 80 controls the detection unit 22 to detect the characteristics of the fuel cell stack S and analyze the state of the fuel cell stack S using the detected characteristics to determine whether or not the fuel cell stack S is under normal operation, And controls the magnitude of the output voltage or output current according to the current state of the stack (S).

The management of such a fuel cell starts from the process of detecting the characteristics of the fuel cell stack S as described above. Specifically, the controller 80 measures the open circuit voltage (OCV) of the fuel cell stack to be analyzed. This OCV means the terminal voltage of the fuel cell stack S in a state in which the load is not connected and the fuel cell 21 is operating and does not mean the theoretical output voltage of the fuel cell stack S. [ The control unit 80 switches the switch S1 in the detecting unit 22 to the ON state so that the test load R1 is connected in series with the fuel cell stack S, The test load voltage is measured. The control unit 80 measures the current temperature of the fuel cell stack S, calculates the test load current using the test load voltage and the resistance value of the test load, The resistance is calculated.

When the current temperature, the open circuit voltage, the test load voltage, and the test load current are calculated as described above, it can be substituted into a predetermined formula to calculate the voltage variation according to the output current.

Specifically, the controller 80 substitutes the measured index, the calculated open circuit voltage, the test load voltage, and the internal resistance into the equation (1), and calculates the variation value of the stack voltage according to the variation of the output current .

Here,? Vstack is the output voltage variation value of the fuel cell stack S, i is the output current, and io is the test load current. A is a constant value that is calculated through the internal resistance and the temperature of the fuel cell stack (S). Here, the control unit 80 can calculate the internal resistance by the above-described test load voltage, test load current, and open circuit voltage, and the test load current can also be calculated by the test load voltage and the resistance value of the test load.

The constant A is calculated by substituting the measured temperature of the fuel cell stack S and the calculated internal resistance into the equation (2).

Here, R is the internal resistance of the fuel cell stack S, T is the temperature of the fuel cell stack S, and? And F are constant values determined in advance.

In this way, the control unit 80 calculates the voltage variation value of the fuel cell stack according to the output current with the characteristic value of the fuel cell stack S, compares it with the reference characteristic value stored in advance and stored The state of the fuel cell stack is analyzed.

More specifically, the reference characteristic value is obtained by calculating the amount of change of the output voltage according to the output current by experimenting with the same cell as the actually used fuel cell. The graph is expressed by a continuous value, a formula thereof, And the variation value of the voltage value with respect to the value. That is, when a continuous graph is expressed, it can be expressed as shown in FIG. Similarly, the characteristic value of the fuel cell stack S may have a graph form as shown in FIG. 3, but the magnitude of the output current with respect to the same current is different from the value shown in the graph of the reference characteristic value.

In particular, the reference characteristic value is provided for the fuel cell stack, while the characteristic value created for the fuel cell stack S includes a plurality of fuel cell cells, and the calculated characteristic values for comparison are compared with each other, Value.

To this end, the controller 80 calculates the comparison characteristic value by dividing the characteristic value described above by n, which is the number of fuel cells, and converting the value into one value of the fuel cell C.

Then, the calculated comparison characteristic value is compared with the reference characteristic value, and the size of the voltage fluctuation is checked to check the state of the fuel cell stack.

More specifically, the controller 80 compares the output voltage value Vstack / n corresponding to the output current i identified by the comparison characteristic value with the output voltage value versus the output current calculated by the previously calculated reference characteristic value . That is, when the output current value is designated as the same value, when the output voltage value is lower than the output voltage value described in the reference characteristic value, it can be determined that an abnormality occurs in the fuel cell stack S or an efficiency decrease occurs . Or the control unit 80 may determine that there is a failure or an efficiency decrease when the output voltage of the comparison characteristic value is different from the reference characteristic value by a predetermined ratio or more.

When such an analysis is performed, the controller 80 transmits the information of the fuel cell stack S and the analysis information to the user, which are generated due to the occurrence of such efficiency deterioration or failure, and confirms the status of the fuel cell stack S Or replacement may be made.

The control unit 80 limits the magnitude of the output current when the voltage of the fuel cell stack S is compared with the reference characteristic value and the voltage greatly decreases compared to the same output current, The fuel cell stack S may perform control to prevent the power cell stack S from being damaged by outputting excessive power.

5 is a flowchart for explaining a state analysis process of the fuel cell stack.

Referring to FIG. 5, the process of analyzing the state of the fuel cell stack according to the present invention includes calculating a reference characteristic value S10, measuring an indicator of the fuel cell stack S20, calculating a characteristic value of the fuel cell stack S30, A comparison characteristic value calculation step S40 and a characteristic value comparison step S50.

The reference characteristic value calculation step S10 is a step of calculating and storing a reference characteristic value for analyzing the state of the fuel cell in advance. The reference characteristic value is a value calculated experimentally or theoretically for the same cell as the fuel cell used in the fuel cell stack S, and may be a value of the output voltage according to the current output from the fuel cell at a specific temperature, Is calculated. This reference characteristic value may be expressed as an equation, a graph of continuous values, or a magnitude or variation value of the output voltage for several arbitrarily specified current values. In particular, the reference characteristic value may include a predetermined reference value, and it is possible to determine whether the fuel cell fails or deteriorates in efficiency through the reference value. Further, the reference values may be provided in plural, and the present invention is not limited to the present invention. The reference characteristic value is transmitted to the controller 80 and stored in a memory or a storage unit (not shown) connected to the controller 80.

The indicator measurement step S20 is a step of measuring an indicator for calculating a characteristic value of the fuel cell stack S using the detection unit 22 of the fuel cell stack S requiring status analysis. In this indicator measurement step (S20), the controller (80) measures the temperature of the fuel cell stack (S) to be analyzed and measures the open circuit voltage of the fuel cell stack. The switch S1 of the detection unit 22 connected to the fuel cell stack S is controlled to measure the test load voltage applied to the test load by connecting the fuel cell stack S and the test load R1 .

In the cell characteristic value calculating step S30, the controller 80 calculates the internal resistance using the measured open circuit voltage, temperature, and test load voltage, calculates a constant A according to the calculated internal resistance, The measured values are applied to Equation (1), and the voltage variation value of the fuel cell stack S according to the output current is used to calculate the characteristic value.

The comparison characteristic value calculation step S40 is a step of calculating the comparison characteristic value by converting the characteristic value of the fuel cell stack S calculated so that the calculated characteristic value can be compared with the reference characteristic value. As described above, the characteristic value of the fuel cell stack S is calculated for the fuel cell stack S in which the plurality of fuel cell cells C are connected in series, and compares the characteristic value with the reference characteristic value calculated for one unit cell The characteristic value of the fuel cell stack S must be converted into the characteristic value of the cell unit. Therefore, the control unit 80 divides the characteristic value of the fuel cell stack S by the number of the fuel cell units C constituting the fuel cell stack S to calculate the comparison characteristic value.

The characteristic value comparison step S50 is a step of comparing the reference characteristic value calculated and stored in advance by the controller 80 with the calculated characteristic value, and analyzing the state of the fuel cell stack according to the comparison result. In the characteristic value comparison step S50, the control unit 80 compares the reference characteristic value with the comparison characteristic value, and compares the magnitude of the output voltage or the variation of the output voltage with respect to the same output current. At this time, the controller 80 checks whether the difference between the output voltage of the reference characteristic value and the variation value of the output voltage or the output voltage of the comparison characteristic value is equal to or greater than a predetermined reference value, It is determined whether the battery stack S is broken or not. The control unit 80 outputs the analysis result to the user through the display unit or provides the result to the user through an external device or another system. When the efficiency of the fuel cell stack S is lowered, the fuel cell stack S performs control for protection such as limiting the output current to prevent burn-out.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, . ≪ / RTI > Accordingly, such modifications are deemed to be within the scope of the present invention, and the scope of the present invention should be determined by the following claims.

10: Battery 20: Fuel cell unit
21: fuel cell 22:
26: DC converter 80:
90: Load

Claims (7)

1. A fuel cell system comprising: a fuel cell stack including a plurality of fuel cell cells that are supplied with fuel containing hydrogen to produce electric power; and a converter connected to the fuel cell stack to convert a voltage output from the fuel cell stack;
A detector configured to correspond to the fuel cell stack and measuring at least one of voltage, current, and temperature of the fuel cell stack; And
Controlling the connection between the detection unit and the fuel cell stack to measure the indicator, calculating a characteristic value of the fuel cell stack using the indicator measured by the detection unit, comparing the measured characteristic value with a previously stored reference characteristic value, And a controller for converting the characteristic value into a comparative characteristic value that can be compared with the reference characteristic value to analyze the state of the battery stack. The method according to claim 1,
The reference characteristic value or the characteristic value or the comparison characteristic value of the fuel cell stack
A graph or an expression of the magnitude of the output voltage or the variation of the output voltage according to the output current of the fuel cell stack or the fuel cell,
Wherein the output voltage is a magnitude of an output voltage corresponding to a predetermined output current value or a variation value of the output voltage. 3. The method of claim 2,
Wherein the reference characteristic value is obtained by calculating a variation value of an output voltage or an output voltage corresponding to the output current for one fuel cell,
Wherein the comparison characteristic value is a value obtained by converting a characteristic value of the fuel cell stack into a characteristic value per one fuel cell cell. The method according to claim 1,
The detection unit
A test load connected to the fuel cell stack;
A switch for connecting or disconnecting the test load and the fuel cell stack;
A voltmeter for measuring an open circuit voltage of the fuel cell stack or a terminal voltage of the test load;
And a thermometer for measuring the temperature of the fuel cell stack. 4. The method according to any one of claims 1 to 3,
The reference characteristic value
And a reference value for determining the state of the fuel cell stack. 6. The method of claim 5,
The control unit
For any output current
The magnitude of the output voltage by the comparison characteristic value and the magnitude of the output voltage by the reference characteristic value or
A variation value of the output voltage by the comparison characteristic value or a variation value of the output voltage by the reference characteristic value
Wherein the state of the fuel cell stack is analyzed by determining whether the range is defined by the reference value. The method according to claim 1,
The control unit
Calculating an internal resistance of the fuel cell stack using a value measured by the detection unit, calculating a constant determined by the internal resistance,
The output voltage of the fuel cell stack or the fuel cell or the variation value of the output voltage
And a log value of a value obtained by dividing an output current according to the output voltage by a current applied to a test load connected to the fuel cell stack, multiplied by the constant.

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