JP5339024B2 - Fuel cell aging method - Google Patents

Description

The present invention relates to aging how the fuel cell to provide a predetermined pre-history to the fuel cell.

In general, fuel cell characteristics include stable power generation characteristics (DC characteristics) and load response characteristics (AC characteristics), and it is important to accurately measure these characteristics in the evaluation of fuel cells. However, in a fuel cell having the property of being affected by the previous history, each characteristic is not stable from time to time, and aging treatment that makes the previous history substantially the same in the previous stage of evaluation, It is common to work to confirm the homology of states. As these methods, homogeneity is confirmed by aging, in which power generation with a constant current is performed until the fuel cell voltage is stabilized, fuel cell current, current-voltage measured value when the voltage is stabilized, or IV curve. There is a technique.
JP 2005-243245 A JP 2005-243562 A JP 2005-251396 A JP 2005-302360 A JP 2006-040869 A

  In recent years, since the stable power generation characteristics of fuel cells have improved, the evaluation of AC characteristics has become important in the evaluation of fuel cells, and it is necessary to perform aging to stabilize the AC characteristics and to confirm the AC characteristics. Has been. However, the conventional aging method for generating electricity at a constant current and the confirmation of homology by the IV measurement value and IV curve in a stable state are the aging and characteristic confirmation for the DC characteristics of the fuel cell. It is not a thing.

  An object of the present invention is to provide an aging method and an aging apparatus capable of performing appropriate aging on AC characteristics.

The fuel cell aging method of the present invention is a fuel cell aging method for giving a predetermined previous history to a fuel cell, the step of repeatedly applying a load voltage or load current that changes at a predetermined sweep speed to the fuel cell, Or repeatedly measuring the state of the fuel cell to which a load current is applied, and determining that aging has been completed when the state of the fuel cell measured by the measuring step is stabilized. In the determining step, a variable using a fuel cell voltage or a fuel cell power generation current is used as an index indicating the state,
In the determining step, when the condition is stable and the state close to a predetermined reference state, it is determined that the aging is completed, the state indicates a response characteristic with respect to an AC load of the fuel cell, before SL sweep rate, characterized in that it is a rate that provides substantial AC voltage load or alternating current load to the fuel cell.
According to this fuel cell aging method, the load voltage or load current that changes at a predetermined sweep speed is repeatedly applied to the fuel cell, so that appropriate aging of the AC characteristics can be performed.

In the determining step, in the fuel cell voltage or the fuel cell power generation current of the fuel cell, when the change of each sweep of the load voltage or the load current is smaller than the predetermined value, the said state of said fuel cell stable and it may be all you.

  According to the fuel cell aging method of the present invention, a load voltage or a load current that changes at a predetermined sweep speed is repeatedly applied to the fuel cell, so that appropriate aging for AC characteristics can be performed.

  Hereinafter, an embodiment of a fuel cell aging method according to the present invention will be described with reference to FIGS.

  FIG. 1 is a block diagram showing a connection state of fuel cells in the aging method of the present embodiment.

  As shown in FIG. 1, a load device 2 is connected to the fuel cell 1, and a current measuring instrument 11 for measuring the fuel cell current (Ifc) is inserted in the connection loop. The fuel cell 1 is connected to a voltage measuring device 12 that measures the fuel cell voltage (Vfc) and a temperature measuring device 13 that measures the fuel cell temperature (Tfc).

  The aging device 3 that performs aging of the fuel cell 1 includes a load control unit 31 that applies a load voltage or a load current that changes at a predetermined sweep speed to the fuel cell 1 by controlling the load device 2, and a load control unit 31. Measuring means 32 for measuring the state of the fuel cell 1 to which a load voltage or load current is applied, and a determination means for determining that aging has been completed when the state of the fuel cell 1 measured by the measuring means 32 is stabilized. 33.

  The load control unit 31, the measurement unit 32, and the determination unit 33 can be configured, for example, by mounting a predetermined program on the aging device 3 that is a computer.

  FIG. 2 is a flowchart showing an aging procedure using the aging device 3.

  In step S <b> 1 of FIG. 2, set values and determination values used for aging are input to the aging device 3.

Here, fuel cell operating temperature: Tset [° C.], minimum control voltage value: VL [V], initial characteristic determination value: Ib [V], initial characteristic determination time: Mb [min], current sweep speed: a [A / Sec], minimum control current value: IL [A], fuel cell temperature tolerance: Ta [° C.], fuel cell temperature judgment time: Mt [min], stability judgment value: Vs [V], reproducibility judgment value Input Vw [V] and reproducibility standard sweepIV: f _ref .

Next, the process proceeds to initial characteristic determination processing. In step S2, the load control unit 31 operates the load device 2 to control the fuel cell voltage: Vfc [V] to be the lowest control voltage value (VL). The fuel cell current: Ifc [A] at that time is measured by the measuring means 32, and in step S3, the maximum value (Ifc _max ) of the fuel cell current (Ifc) during the initial characteristic determination time (Mb) is changed to the minimum value (Ifc _max ). If the difference value obtained by subtracting Ifc _min ) is equal to or smaller than the initial characteristic determination value (Ib), that is, waits for the expression (1) to be established, the process proceeds to the temperature stability determination process.

Ifc (Mb) = Ifc _max −Ifc _min ≦ Ib (1)

  In the temperature stability determination process, in step S4, the load device 2 is controlled by the load control means 31, and the current sweep speed (a) of the fuel cell current (Ifc) is held. Thus, the fuel cell current (Ifc) increases at a constant current sweep rate (a) from the lowest control current value (IL) to a value at which the fuel cell voltage (Vfc) becomes the lowest control voltage value (VL). Be controlled. After the fuel cell voltage (Vfc) reaches the minimum control voltage value (VL), the operation of increasing the fuel cell current (Ifc) from the minimum control current value (IL) is repeated again. After the fuel cell voltage (Vfc) reaches the minimum control voltage value (VL), the fuel cell current (Ifc) is changed to the minimum control current value (IL) at a constant current sweep speed (for example, current sweep speed (a)). You may repeat the operation | movement to reduce to.

Next, in step S5, every time the fuel cell temperature determination time (Mt) elapses, the maximum value (Tfc _max ) and the minimum value (Tfc _min ) of the fuel cell temperature (Tfc) during that time are acquired by the measuring means 32. . Then, the determination means waits until the deviation from the fuel cell operating temperature (Tset) becomes equal to or less than the fuel cell temperature allowable value (Ta), that is, the expressions (2-1) and (2-2) are satisfied. The process proceeds to the state stability determination process by 33.

Tfc _max −Tset ≦ Ta (2)

Tset−Tfc _min ≦ Ta (Formula 2-2)

  In the state stability determination process, in step S6, a calculation for evaluating the state stability of the fuel cell is executed. Here, the sweep IV data fn in the n-th current sweep cycle is defined as in equation (3-1), where α is a variable that increases by 1 for each measurement cycle (measurement cycle in each current sweep period).

fn = (I _{α, n} , V _{α, n} ) Equation (3-1)

  Further, the difference value Δfn between the nth and n−1th fn in the same measurement cycle is expressed by the equation (3-2), and the difference value between the fuel cell current (Ifc) and the fuel cell voltage (Vfc) is expressed by the equation It is defined by (3-3) and formula (3-4).

Δf _n = f _n −f _n−1 = f (ΔI _{α, n} , ΔV _{α, n} ) (3-2)

ΔI _{α, n} = I _{α, n} −I _{α, n−1} Formula (3-3)

ΔV _{α, n} = V _{α, n} −V _{α, n−1} Formula (3-4)

  In step S7, the condition that the difference value of the fuel cell voltage (Vfc) is equal to or lower than the stability determination value (Vs) is established twice, that is, after the expressions (3-5) and (3-7) are satisfied, After waiting for the expressions (3-6) and (3-8) to be established, the process proceeds to the process of determining reproducibility.

△ V _α, the maximum value of _{n M ax (△ V α,} n), the minimum value _{M in (△ V α, n} ) to.
| M _in (ΔV _{α, n−1} ) | ≦ Vs and | M _ax (ΔV _{α, n−1} ) | ≦ Vs (3-5)
| M _in (ΔV _{α, n} ) | ≦ Vs and | M _ax (ΔV _{α, n} ) | ≦ Vs (3-6)
Current difference judgment value: I _{S. Let} the maximum value of _{ΔI α, n be} Max (ΔI _{α, n} ) and the minimum value be M _in (ΔI _{α, n} ).
For formula (3-5),
| M _in (ΔI _{α, n−1} ) | ≦ Is and | M _ax (ΔI _{α, n−1} ) | ≦ Is (3-7)
For formula (3-6),
| M _in (ΔI _{α, n} ) | ≦ Is and | M _ax (ΔI _{α, n} ) | ≦ Is (3-8)
On the condition that

In the reproducibility determination process, in step S8, as shown in Expression (4-2), the difference between the reproducibility standard (sweep IV: f _ref ) defined as Expression (4-1) and fn is used as the reproducibility determination value. Compare with (Vw).

f _ref = (I _{α, ref} , V _{α, ref} ) Equation (4-1)

Let V _{α, ref} −V _{α, n be} the maximum value Max — _{α, n} and the minimum value be M in _{—α, n} .
| M _{in_α, n} | ≦ Vw and | M _{ax_α, n} | ≦ Vw Expression (4-2)

  In step S9, the aging process is terminated after waiting for the expression (4-2) to be established. Thereby, the state stability and reproducibility of the fuel cell are ensured, and thereafter, the process proceeds to a predetermined measurement.

  As described above, in this embodiment, a load current that changes at a predetermined sweep speed is applied to the fuel cell. However, such a current change is substantially equivalent to applying an alternating current load, and aging of the AC characteristics is performed. It will be implemented. For this reason, appropriate aging with respect to AC characteristics can be implemented by confirming the stability and reproducibility of the fuel cell.

  In the above embodiment, the initial characteristic determination (steps S2 to S3) may be omitted, and the temperature stability determination (steps S4 to S5) may be included. The same effect can be obtained by using a voltage-based sweep instead of the current-based sweep and changing the fuel cell voltage at a predetermined sweep speed.

  As described above, according to the fuel cell aging method of the present invention, the load voltage or load current that changes at a predetermined sweep speed is repeatedly applied to the fuel cell, so that appropriate aging of the AC characteristics can be performed. Further, according to the fuel cell aging device of the present invention, a load voltage or a load current that changes at a predetermined sweep speed is applied to the fuel cell, and it is determined that the aging is completed when the state of the fuel cell is stabilized. Appropriate aging for AC characteristics can be performed.

The scope of application of the present invention is not limited to the above embodiment. The present invention is, against the aging how the fuel cell to provide a predetermined pre-history to the fuel cell, can be widely applied.

The block diagram which shows the connection state of the fuel cell in the aging method of one Embodiment. The flowchart which shows the procedure of the aging using an aging apparatus.

Explanation of symbols

3 Aging device 31 Load control means 32 Measuring means 33 Determination means

Claims (2)

In a fuel cell aging method that gives a predetermined previous history to a fuel cell,
Repeatedly applying to the fuel cell a load voltage or load current that changes at a predetermined sweep rate;
Repeatedly measuring the state of the fuel cell to which a load voltage or load current is applied;
Determining that aging is completed based on the state of the fuel cell measured by the measuring step;
With
In the determining step, using a variable using a fuel cell voltage or a fuel cell power generation current as an index indicating the state,
In the determining step, when the state is stable and the state is close to a predetermined reference state, it is determined that aging has ended,
The state indicates a response characteristic of the fuel cell to an AC load,
The fuel cell aging method, wherein the sweep speed is a speed at which a substantial alternating voltage load or alternating current load is applied to the fuel cell. In the determining step, the state of the fuel cell is determined when a change in the load voltage or the fuel cell power generation current of the fuel cell for each sweep of the load voltage or the load current becomes smaller than a predetermined value. The fuel cell aging method according to claim 1, wherein the method is regarded as stable .

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