JP2018147615A - Fuel cell system - Google Patents

Abstract

A fuel cell system capable of performing an optimal recovery process according to an operating state is provided. SOLUTION: A fuel cell, a secondary battery that is charged by electric power supplied from the fuel cell, and a recovery means for generating a fuel cell at a voltage lower than a voltage at the time of charging and performing a recovery process of the fuel cell (S14), a confirmation means (S15) for generating the fuel cell at a current lower than the current at the time of charging and confirming the voltage of the fuel cell, and an operation mode for charging from the fuel cell to the secondary battery are two A selection means (S2) for selecting a charge mode for increasing the charging rate of the secondary battery, and a control for alternately performing the recovery means and the confirmation means prior to charging the secondary battery when the charge mode is selected. And a fuel cell system. [Selection] Figure 2

Description

  The present invention relates to a fuel cell system equipped with a secondary battery.

  A fuel cell is a cell that generates electricity by, for example, an electrochemical reaction between hydrogen and oxygen. In recent years, a system combining such a fuel cell and a secondary battery has been developed.

JP 2008-192468 A International Publication No. 2013/128610 Pamphlet

  The fuel cell has been operated continuously for a long time, resulting in oxidation degradation of the air electrode catalyst, degradation due to chemical adsorption and physical adsorption of degradation degradation products derived from membrane electrode assemblies, metal separators, metal piping, resin piping and other system-derived impurities. There are problems that cause degradation due to chemical adsorption and physical adsorption, and chemical adsorption due to atmospheric sulfur and salt. Such degradation has problems that impede proton conduction of the electrolyte membrane, accelerate chemical degradation of the electrolyte membrane, and accelerate corrosion of the metal separator.

  In order to solve the above-described problems, the fuel cell is subjected to a recovery process for recovering the above-described deterioration. However, in a system in which the fuel cell and the secondary battery are combined, the fuel cell is charged from the fuel cell to the secondary battery. It is desirable to carry out the recovery process in consideration of the driving situation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell system capable of performing an optimal recovery process in accordance with an operation state.

A fuel cell system according to a first invention for solving the above-mentioned problems is as follows.
A fuel cell;
A secondary battery that is charged by electric power supplied from the fuel cell;
Recovery means for generating the fuel cell at a voltage lower than the voltage at the time of charging and performing recovery processing of the fuel cell;
Confirmation means for generating the fuel cell at a current lower than the current at the time of charging and confirming the voltage of the fuel cell;
Control means for alternately performing the recovery means and the confirmation means at the time of charging.

A fuel cell system according to a second invention for solving the above-mentioned problems is as follows.
In the fuel cell system according to the first invention,
A selection means for selecting a first mode for increasing a charging rate of the secondary battery as an operation mode of charging from the fuel cell to the secondary battery;
When the first mode is selected by the selection means, the control means alternately performs the recovery means and the confirmation means before charging the secondary battery.

A fuel cell system according to a third invention for solving the above-mentioned problem is as follows.
In the fuel cell system according to the second invention,
The control means performs the recovery means and the confirmation means alternately and continuously.

A fuel cell system according to a fourth invention for solving the above-described problems is as follows.
In the fuel cell system according to any one of the second and third inventions,
The selection means has a second mode for maintaining the charging rate of the secondary battery as the operation mode,
The control means intermittently implements the recovery means so that the charging rate of the secondary battery is maintained when the second mode is selected by the selection means.

A fuel cell system according to a fifth invention for solving the above-mentioned problem is as follows.
In the fuel cell system according to any one of the first to fourth inventions,
The control means ends the alternate implementation of the recovery means and the confirmation means when the voltage of the fuel cell confirmed by the confirmation means exceeds a predetermined voltage.

A fuel cell system according to a sixth invention for solving the above-mentioned problems is as follows.
In the fuel cell system according to any one of the first to fifth inventions,
Supply amount adjusting means for adjusting the supply amounts of fuel gas and oxidizing gas supplied to the fuel cell, temperature adjusting means for adjusting the temperature of the fuel cell, and humidity adjustment for adjusting the humidity of the fuel gas and the oxidizing gas Having at least one of the means,
When the recovery means and the confirmation means are implemented, the control means lowers the supply amounts of the fuel gas and the oxidant gas from before the adjustment by the supply amount adjustment means, and the temperature adjustment means reduces the supply amount of the fuel cell. At least one of raising the temperature from before the adjustment and lowering the humidity of the fuel gas and the oxidizing gas from before the adjustment by the humidity adjusting means is performed, and the internal resistance of the fuel cell is set before the implementation. It is characterized by being higher than the internal resistance.

  According to the present invention, the electric power generated during the recovery process of the fuel cell can be used for charging the secondary battery, and the optimal recovery can be performed according to the driving situation.

It is a block diagram which shows an example of embodiment of the fuel cell system which concerns on this invention. It is a figure explaining the control method in the charge mode implemented with the fuel cell system shown in FIG. 1, (a) is a flowchart explaining the charge driving | operation including a recovery process, (b) is the recovery process itself It is a flowchart explaining these. It is a time chart explaining the control method in the charge mode shown in FIG. It is a figure explaining the control method in the save mode implemented with the fuel cell system shown in FIG. 1, (a) is a flowchart explaining the save driving | operation including a recovery process, (b) is the recovery process itself It is a flowchart explaining these. It is a time chart explaining the control method in the save mode shown in FIG. It is a figure explaining the control method in the mode without designation implemented with the fuel cell system shown in Drawing 1, and is a flow chart explaining maintenance operation including recovery processing. It is a time chart explaining the control method in the non-designation mode shown in FIG.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described with reference to FIGS. Here, the fuel cell vehicle is illustrated as having the fuel cell system according to the present invention, but the present invention can also be applied to devices other than vehicles, such as aircraft fuel cell systems and stationary fuel cell systems. . Here, the fuel gas supplied to the fuel cell is described as hydrogen, and the oxidizing gas is described as oxygen. However, any other equivalent gas may be used.

[Example 1]
FIG. 1 is a configuration diagram showing a fuel cell system of the present embodiment. 2, FIG. 4, and FIG. 6 are flowcharts for explaining a control method implemented in the fuel cell system shown in FIG. 3 is a time chart explaining the control method shown in FIG. 2, FIG. 5 is a time chart explaining the control method shown in FIG. 4, and FIG. 7 is the control shown in FIG. It is a time chart explaining a method.

  The fuel cell 11 has a plurality of stacked cells and generates power by an electrochemical reaction between hydrogen and oxygen. The fuel cell 11 is provided with a temperature sensor 11a for measuring the temperature of the cell, a resistance sensor 11b for measuring the internal resistance of the cell, a voltage sensor 11c for measuring the voltage of the cell, a current sensor 11d for measuring the current of the cell, and the like. It has been. The fuel cell 11 may be a known one, and a description of its configuration is omitted here, but, for example, a solid polymer fuel cell can be used.

  Hydrogen is supplied to the fuel cell 11 from the hydrogen tank 12 through the supply line G1, the non-humidified line G2, and the humidified line G3. The supply line G1 is provided with an adjustment valve 13 (supply amount adjustment means) for adjusting the supply amount of hydrogen and a three-way valve 14, and the humidification line G3 is provided with a humidifier 15 (humidity adjustment means) for humidifying hydrogen. It has been.

  When hydrogen is supplied without humidification, the three-way valve 14 is used to switch to the non-humidification line G <b> 2 to supply non-humidified hydrogen to the fuel cell 11. On the other hand, when hydrogen is humidified and supplied, the three-way valve 14 is used to switch to the humidification line G3, the humidifier 15 humidifies the hydrogen, and the humidified hydrogen is supplied to the fuel cell 11. Alternatively, the three-way valve 14 may be used to adjust the amount of hydrogen supplied to the non-humidified line G2 and the amount of hydrogen supplied to the humidified line G3.

  The fuel cell 11 is supplied with air (oxygen) sucked by the compressor 16 (supply amount adjusting means) via a filter (not shown) via a supply line G4, a non-humidification line G5, and a humidification line G6. Is done. This compressor 16 can adjust the supply amount of oxygen. The supply line G4 is provided with a three-way valve 17, and the humidification line G6 is provided with a humidifier 18 (humidity adjusting means) for humidifying air.

  When supplying air without humidification, the three-way valve 17 is used to switch to the non-humidification line G5 to supply non-humidified air to the fuel cell 11. On the other hand, when air is humidified and supplied, the three-way valve 17 is used to switch to the humidification line G 6, the air is humidified by the humidifier 18, and the humidified air is supplied to the fuel cell 11. Further, the three-way valve 17 may be used to adjust the amount of air supplied to the non-humidified line G5 and the amount of air supplied to the humidified line G6.

  Although not shown in the drawings, the humidifiers 15 and 18 are recirculated with unreacted hydrogen and air supplied to the fuel cell 11, respectively. Since the unreacted hydrogen and air that have been circulated are humidified with the water generated in the fuel cell 11, the moisture exchange is performed between the humidified hydrogen and the air and the newly supplied hydrogen and air. The newly supplied hydrogen and air can be supplied by humidification. At this time, if the refluxed unreacted hydrogen can be reused and supplied to the fuel cell 11, the consumption of hydrogen can be suppressed. Note that humidification water may be separately supplied to the humidifiers 15 and 18, and hydrogen and air may be humidified using the separately supplied water.

  The fuel cell 11 is connected to a DC-DC converter 21, a secondary battery 22, an inverter 23, and a drive motor 24 via a power line P1.

  The DC-DC converter 21 steps up or steps down the output voltage of direct current power generated by the fuel cell 11. Further, the secondary battery 22 charges the direct current power supplied from the DC-DC converter 21 and supplies the direct current power to the inverter 23. As the secondary battery 22, a known battery can be used. For example, a lithium ion battery can be used. The secondary battery 22 is provided with a control unit 25 that controls the secondary battery 22, and this control unit 25 detects an SOC (State of Charge) of the secondary battery 22 to be described later. ing.

  Further, the inverter 23 converts the DC power supplied from the secondary battery 22 or the DC power supplied from the DC-DC converter 21 and the secondary battery 22 into AC power. And the drive motor 24 is driven using the alternating current power converted by the inverter 23, and this makes a fuel cell vehicle drive | work.

  Further, an AC-DC converter 26 and a power plug 27 are connected to the secondary battery 22. That is, it has a configuration of a plug-in type fuel cell vehicle. Therefore, it is possible to charge not only from the fuel cell 11 but also from electric power supplied from the outside. For example, if the power plug 27 is connected to a household power source, the AC-DC converter 26 is supplied from the household power source. AC power is converted to DC power and supplied to the secondary battery 22.

  The fuel cell 11 is provided with a main water channel W1 and a bypass water channel W2 through which cooling water for cooling the fuel cell 11 flows. The main water channel W1 is provided with a pump 31, a three-way valve 32, and a radiator 33 (temperature adjusting means).

  The pump 31 supplies cooling water to the fuel cell 11, and the cooling water supplied to the fuel cell 11 absorbs waste heat of the fuel cell 11 and is supplied to the radiator 33. The radiator 33 cools the cooling water that has absorbed the waste heat. In this way, the cell temperature of the fuel cell 11 is adjusted.

  Depending on the cell temperature of the fuel cell 11, the three-way valve 32 may be used to switch the cooling water to either the radiator 33 or the bypass water channel W2, or the amount of cooling water supplied to the radiator 33 and the bypass water channel W2. You may adjust the quantity of the cooling water supplied to.

  And the apparatus mentioned above is controlled by the control apparatus 50 (control means). The control device 50 is connected to an accelerator opening sensor 51 that detects the accelerator opening of the accelerator pedal, a mode selection switch 52 (selecting means) that selects an operation mode, and the like. The mode selection switch 52 is a switch for selecting one from a charge mode, a save mode, and a non-designation mode, which will be described later. This non-designated mode is a mode that is neither a charge mode nor a save mode.

  The SOC of the secondary battery 22 is input from the control unit 25, the cell temperature measured by the temperature sensor 11a, the internal resistance of the cell measured by the resistance sensor 11b, and the cell voltage measured by the voltage sensor 11c. The cell current measured by the current sensor 11d is input. In addition, drive power from the drive motor 24 is input from the inverter 23. Based on these inputs, the control device 50 controls the above-described devices to perform control described later.

  As the control device 50, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), an ECU (Electronics Control Unit) having an input / output interface, and the like can be used.

  In the fuel cell system of the present embodiment, when charging from the fuel cell 11 to the secondary battery 22, charging is performed in any one of the charge mode, the save mode, and the non-designation mode, and these are the mode selection switches 52 described above. Is selected.

  In the charge mode (first mode), the fuel cell 11 is operated so that the SOC of the secondary battery 22 becomes a predetermined high SOC (for example, 80%). In the save mode (second mode), the fuel cell 11 is operated so that the current SOC is maintained by the secondary battery 22. Further, even in the non-designation mode (second mode), the fuel cell 11 is operated so that the secondary battery 22 maintains a minimum SOC that does not run out of electricity.

  Even when any one of the charge mode, the save mode, and the non-designated mode is selected, the recovery process of the fuel cell 11 is necessary, and the recovery process depends on the driving situation, that is, the charge mode, the save mode, and the designated mode. It is necessary to carry out according to the selection state of the none mode. Hereinafter, the charge mode, the save mode, and the non-designation mode will be described.

<Charge mode>
The charge operation and the recovery process in the charge mode will be described with reference to FIGS. 2 and 3 together with FIG.

(Step S1)
The control device 50 refers to the SOC of the secondary battery 22 using the control unit 25.

(Step S2)
The control device 50 confirms whether or not the selection by the mode selection switch 52 is the charge mode. If the mode is the charge mode, the control device 50 proceeds to step S3. If not, the control device 50 proceeds to the return.

(Step S3)
The control device 50 confirms whether or not the voltage drop width from the previous recovery process is larger than the predetermined voltage width, or whether or not the elapsed time from the previous recovery process is larger than the predetermined time. If the voltage drop width is larger than the predetermined voltage width, or if the elapsed time from the previous recovery process is longer than the predetermined time, the process proceeds to step S4. Otherwise, that is, the voltage drop width is equal to or smaller than the predetermined voltage width. Alternatively, if the elapsed time is equal to or shorter than the predetermined time, the process proceeds to step S7.

  Here, the voltage drop width from the previous recovery process is calculated by subtracting the current cell voltage of the fuel cell 11 from the cell voltage of the fuel cell 11 last confirmed during the previous recovery process. These cell voltages may be generated, for example, by the same power generation as a predetermined current power generation (see step S15) described later, and the cell voltage of the fuel cell 11 at the time of power generation may be measured by the voltage sensor 11c. The elapsed time from the previous recovery process is calculated by subtracting the current time from the time of the previous recovery process.

(Step S4)
The control device 50 confirms the power when the cell voltage of the fuel cell 11 is 0.2V (hereinafter referred to as 0.2V power), the current drive power, and the current received power of the secondary battery 22 [(0 If 2V power-driving power) <accepted power], the process proceeds to step S5. If [(0.2V power-driving power) ≧ accepted power], the process proceeds to step S6. Here, it is determined whether or not the received power of the secondary battery 22 remains, that is, whether or not there is a capacity capable of charging the secondary battery 22, and if there is, the process proceeds to step S5. Proceed to S6.

  Here, the power at 0.2V may be referred to the power at 0.2V power generation (see step S14 described later) performed immediately before or immediately before. The power at this time is measured using the voltage sensor 11c and the current sensor 11d. Further, the drive power is input from the inverter 23, and the received power is based on the SOC input from the control unit 25. In addition, 0.2V here is a reduction voltage for a recovery process in 0.2V power generation, which will be described later. If the reduction voltage in the recovery process is changed, this 0.2V is adjusted to this reduction voltage. Are also changed to other voltages.

(Steps S5 and S6)
If the secondary battery 22 has a capacity capable of being charged, a recovery process is performed in step S5. If there is no capacity capable of charging the secondary battery 22, a recovery process under the output reduction control is performed in step S6. Is called. The recovery process and the recovery process under the output reduction control will be described in steps S11 to S15 described later.

(Step S7)
After completion of the recovery process or the recovery process under the output reduction control, the fuel cell 11 is operated so that the charge operation, that is, the SOC of the secondary battery 22 becomes a predetermined high SOC (for example, 80%).

  Then, the recovery process and the recovery process under the output reduction control are performed according to the following procedure. The recovery process under the output reduction control is the same procedure as the recovery process except for the output reduction control described later.

(Step S11)
The control device 50 refers to the cell voltage of the fuel cell 11 at the time of predetermined current power generation. Specifically, the current fuel cell 11 performs the same power generation as a predetermined current power generation (see step S15 described later), the cell voltage at the time of the power generation is measured by the voltage sensor 11c, and is determined as the current cell voltage. This will be described with reference to FIG. 3. The predetermined current generation A2 is first performed, and the current cell voltage is obtained. The predetermined current is a current lower than the current when charging the secondary battery 22.

(Step S12)
If the voltage obtained by subtracting the previous cell voltage from the current cell voltage is less than 0, the control device 50 proceeds to step S13, and if it is greater than or equal to 0, ends the recovery process. The previous cell voltage is the cell voltage that was confirmed last during the previous recovery process and is the cell voltage of the fuel cell 11 at the time of the predetermined current power generation. The cell voltage measured by the voltage sensor 11c is used as the previous cell voltage. It is recorded.

  When the power generation efficiency of the fuel cell 11 is recovered by the recovery process using 0.2 V power generation performed in Step 14 described later, the cell voltage increases. In step S12, it is determined whether or not the recovery process of the fuel cell 11 is necessary by checking the current cell voltage. When the current cell voltage becomes equal to or higher than the previous cell voltage (predetermined voltage), it is determined that the recovery is completed. doing.

(Step S13)
Similar to step S4 described above, the control device 50 confirms the 0.2V hour power, the current drive power, and the current received power of the secondary battery 22, and [(0.2V hour power−drive power) <accepted. If [power], the process proceeds to step S14, and if [(0.2 V power-drive power) ≧ accepted power], the process proceeds to return. That is, also here, it is determined whether or not there is a capacity for charging the secondary battery 22.

(Step S14; recovery means)
The control device 50 performs 0.2V power generation in the fuel cell 11 to recover the deterioration of the fuel cell 11. At this time, not only recovery of deterioration of the fuel cell 11 is performed, but also the output (power generation amount) from the fuel cell 11 is increased, and as a result, the secondary battery 22 is also charged, The SOC of the battery 22 will also increase. This 0.2V power generation may be performed for a predetermined power generation time set in advance, or when the time change of the SOC of the secondary battery 22 is negative (for example, the request of the drive motor 24). When the output is large), the time for the 0.2V power generation may be lengthened and the time for charging the secondary battery 22 may be lengthened.

  Moreover, 0.2V mentioned above is a reduction voltage in a recovery process, and is a voltage lower than the voltage at the time of charging the secondary battery 22. By reducing the cell voltage to 0.2V, the catalyst of the fuel cell 11 is activated and the recovery process of the fuel cell 11 is performed. Note that the reduction voltage of 0.2 V is merely an example, and can be appropriately changed depending on the adsorbing substance that causes the deterioration.

(Step S15; confirmation means)
The control device 50 performs predetermined current power generation in the fuel cell 11. In such power generation at a predetermined current, the recovery of the fuel cell 11 is confirmed by measuring the cell voltage of the fuel cell 11 with the voltage sensor 11c. After the predetermined current generation, steps S11 to S15 are repeated until the condition of step S12 is satisfied, and the deterioration of the fuel cell 11 is recovered.

  Note that, as described above, the predetermined current power generation here is generated with a current lower than the current when charging the secondary battery 22, so the output (power generation amount) from the fuel cell 11 is small, and the secondary battery The amount of charge to the battery 22 is not large.

  Steps S14 and S15 described above will be described with reference to FIG. 3. In the charge mode, when it is determined that the recovery process is necessary, the 0.2V power generation A1 and the predetermined current power generation A2 It will be carried out alternately and continuously. Here, since the power generated by the 0.2V power generation A1 can be charged to the secondary battery 22, the 0.2V power generation A1 and the predetermined current power generation A2 are alternately and continuously performed while charging the secondary battery 22. Will be. Then, the cell voltage at the predetermined current power generation A2 rises with the implementation of 0.2V power generation A1, as shown by the dotted arrow in FIG. 3, and the recovery ends when the current cell voltage becomes equal to or higher than the previous cell voltage. It has become.

  After the recovery is completed, the normal charge operation is performed as described in step S7 above. Referring to FIG. 3, after the completion of the recovery process by the 0.2V power generation A1 and the predetermined current power generation A2, the charge operation A3 is performed. Here, the SOC of the secondary battery 22 is 80%. The fuel cell 11 is operated. As described above, in the charge mode, the recovery process is performed by alternately performing the 0.2V power generation A1 and the predetermined current power generation A2 before the charge operation A3. Therefore, the power generation efficiency is improved in the charge operation A3. The fuel cell 11 can generate electric power.

  As described above, in the charge mode, the recovery process is started immediately after the start of the mode, and the recovery process is continuously performed, so that the secondary battery 22 is charged during the recovery process and the fuel cell. 11 power generation efficiency can be improved. After the recovery process, the secondary battery 22 can be charged by the fuel cell 11 in a state where the power generation efficiency is improved. In this way, the electric power generated when recovering the deterioration of the fuel cell 11 is used for charging the secondary battery 22 to improve the SOC of the secondary battery 22 and to achieve optimum recovery in accordance with the charge mode. It can be carried out.

  Next, output reduction control will be described. In order to reduce and control the output of the fuel cell 11, that is, to generate power with low efficiency, it is necessary to increase the internal resistance of the cell of the fuel cell 11, and at least one of the following conditions 1 to 3 Can be implemented. Naturally, a combination of a plurality of conditions from conditions 1 to 3 may be performed.

Condition 1: The supply amount of hydrogen and oxygen is lowered.
Condition 2: The cell temperature is raised.
Condition 3: Reduce humidification.

  For example, when the condition 1 is performed, that is, when the supply amounts of hydrogen and oxygen are lowered, the control device 50 controls the adjustment valve 13 and the compressor 16 to lower the supply amounts of hydrogen and oxygen from those before the adjustment. ing.

  Further, when the condition 2 is performed, that is, when the cell temperature is increased, the control device 50 controls the pump 31 to decrease the flow rate of the cooling water, thereby increasing the cell temperature from before the adjustment.

  Further, when the condition 3 is performed, that is, when the humidification is lowered, the control device 50 controls the humidifiers 15 and 18 to lower the humidification of hydrogen and oxygen from before the adjustment.

  If at least one of the above conditions 1 to 3 is implemented, the internal resistance of the cells of the fuel cell 11 is increased from before implementation, and heat generation is promoted while power generation is suppressed. When the SOC of the secondary battery 22 is high and the secondary battery 22 cannot be charged, the above-described steps S11 to S15 may be performed with such output reduction control. Moreover, in such output reduction control, the consumption of hydrogen can also be suppressed.

<Save mode>
The save operation and the recovery process in the save mode will be described with reference to FIGS. 4 and 5 together with FIG.

(Step S21)
The control device 50 refers to the SOC of the secondary battery 22 using the control unit 25.

(Step S22)
The control device 50 confirms whether the selection of the mode selection switch 52 is the save mode. If the mode is the save mode, the control device 50 proceeds to step S23. If not, the control device 50 proceeds to return. In this save mode, the SOC when the save mode is selected is stored as the save SOC, and the subsequent control is performed so as to maintain this save SOC.

(Step S23)
The control device 50 confirms whether or not the voltage drop width from the previous recovery process is larger than the predetermined voltage width, or whether or not the elapsed time from the previous recovery process is larger than the predetermined time. If the voltage drop width is larger than the predetermined voltage width, or if the elapsed time from the previous recovery process is larger than the predetermined time, the process proceeds to step S24. Otherwise, that is, the voltage drop width is equal to or smaller than the predetermined voltage width. Alternatively, if the elapsed time is equal to or shorter than the predetermined time, the process proceeds to step S27. The voltage drop width and elapsed time here are as described in step S3 above.

(Step S24)
The control device 50 checks the power at 0.2V, the current drive power, and the current received power of the secondary battery 22, and if [(0.2V power−drive power) <accepted power], step S25. If [(0.2V power-drive power) ≧ accepted power], the process proceeds to step S26. That is, it is determined whether or not there is a capacity for charging the secondary battery 22. The power at 0.2 V, the drive power, and the received power here are also as described in step S4 above.

(Steps S25 and S26)
If there is a capacity capable of charging the secondary battery 22, a recovery process is performed in step S25, and if there is no capacity capable of charging the secondary battery 22, a recovery process under the output reduction control is performed in step S26. Is called. The recovery process and the recovery process under the output reduction control will be described in steps S31 to S36 described later.

(Step S27)
After the recovery process or the recovery process under the output lowering control is completed, the fuel cell 11 is operated so as to save operation, that is, to maintain the SOC of the secondary battery 22 at the saved SOC (for example, 40%).

  Then, the recovery process and the recovery process under the output reduction control are performed according to the following procedure. The recovery process under the output reduction control is the same procedure as the recovery process except for the output reduction control described above.

(Step S31)
The control device 50 refers to the cell voltage of the fuel cell 11 at the time of predetermined current power generation. Specifically, the current fuel cell 11 performs the same power generation as the predetermined current power generation (see step S36 described later), the cell voltage at the time of the power generation is measured by the voltage sensor 11c, and is determined as the current cell voltage. This will be described with reference to FIG. 5. The predetermined current generation B2 is first performed, and the current cell voltage is obtained. The predetermined current here is also as described in step S11 above.

(Step S32)
If the voltage obtained by subtracting the previous cell voltage from the current cell voltage is less than 0, the control device 50 proceeds to step S33, and if it is greater than or equal to 0, ends the recovery process. Here, the same process as step S12 described above is performed, and it is determined whether or not the recovery process of the fuel cell 11 is necessary by checking the current cell voltage, and the current cell voltage is the previous cell voltage (predetermined). If the voltage becomes higher than the (voltage), it is determined that the recovery is complete.

(Step S33)
As in step S24 described above, the control device 50 confirms the 0.2V hour power, the current drive power, and the current received power of the secondary battery 22, and [(0.2V hour power−drive power) <accepted. If [Power], the process proceeds to step S34, and if [(0.2 V power-drive power) ≧ accepted power], the process proceeds to return. That is, also here, it is determined whether or not there is a capacity for charging the secondary battery 22.

(Step S34)
The control device 50 checks the current SOC of the secondary battery 22 (hereinafter referred to as the current SOC), and when [current SOC ≦ (save SOC−recovered SOC / 2)] is established, the process proceeds to step S35, and otherwise In the case, that is, [current SOC> (save SOC-recovery SOC / 2)], the process proceeds to return. The recovery SOC is estimated by subtracting the current drive power amount from the previous or immediately previous 0.2V power generation. Further, the SOC and the electric energy may be average values for a predetermined time.

(Step S35; recovery means)
The control device 50 performs 0.2V power generation in the fuel cell 11 to recover the deterioration of the fuel cell 11. At this time, not only the deterioration of the fuel cell 11 is recovered, but also the output from the fuel cell 11 is increased. As a result, the secondary battery 22 is also charged, so that the SOC of the secondary battery 22 is obtained. However, in this save mode, since it is necessary to suppress the fluctuation of the SOC, 0.2V power generation is performed during the predetermined power generation time in which the SOC increases by the recovery SOC described above. . Moreover, about 0.2V here is as having described in above-mentioned step S14, and can be changed suitably.

  Steps S34 → S35 described above will be described with reference to FIG. 5. When the saved SOC is 40% and the recovery SOC is 4%, when the current SOC is 38% or less, the process proceeds to step S35, and 0.2V Power generation is started, and by performing 0.2 V power generation for the predetermined power generation time, the recovery SOC = 4% is charged, and the current SOC is charged to 42%.

(Step S36; confirmation means)
The control device 50 performs predetermined current power generation in the fuel cell 11. In such power generation at a predetermined current, the recovery of the fuel cell 11 is confirmed by measuring the cell voltage of the fuel cell 11 with the voltage sensor 11c. After the predetermined current generation, steps S31 to S36 are repeated until the condition of step S32 is satisfied, and recovery of deterioration of the fuel cell 11 is performed. Note that the predetermined current power generation here is not a large amount of charge to the secondary battery 22 as described in step S15 above.

  Steps S35 and S36 described above will be described with reference to FIG. 5. In the save mode, when it is determined that the recovery process is necessary, the 0.2V power generation B1 and the predetermined current power generation B2 are output until the recovery is determined to be completed. It will be performed alternately. Here, since it is necessary to maintain the SOC of the secondary battery 22 at the save SOC, unlike the charge mode, 0.2V power generation B1 is performed intermittently. That is, while suppressing the fluctuation of the SOC of the secondary battery 22, the 0.2V power generation B1 and the predetermined current power generation B2 are alternately performed, and the 0.2V power generation B1 is intermittently performed.

  In this save mode, the interval between the 0.2V power generation B1 and the predetermined current power generation B2 changes according to the amount of drive power currently used, and the drive power is large (the required output of the drive motor 24 is large). ), The interval is shortened, and when the drive power is small (the required output of the drive motor 24 is small), the interval is long. Then, the cell voltage in the predetermined current power generation B2 rises with the implementation of 0.2V power generation B1, as shown by the dotted arrow in FIG. 5, and the recovery ends when the current cell voltage becomes equal to or higher than the previous cell voltage. It has become.

  After the recovery is completed, a normal save operation is performed as described in step S27 above. Referring to FIG. 5, after completion of the recovery process by the 0.2 V power generation B1 and the power generation B2 at a predetermined current, the save operation B3 is performed. Here, the SOC of the secondary battery 22 is maintained at 40%. Thus, the operation of the fuel cell 11 is performed.

  Note that the above-described 0.2V power generation B1 and the predetermined current power generation B2 are preferably performed after the output reduction control described above is performed, particularly when the secondary battery 22 cannot accept charging.

  As described above, in the save mode, the recovery process is started immediately after the start of the mode, and the recovery process in which the fluctuation of the SOC is suppressed is performed, thereby maintaining the SOC of the secondary battery 22 and the fuel cell 11. It is possible to improve the power generation efficiency. In this way, the electric power generated when recovering the deterioration of the fuel cell 11 is used for charging the secondary battery 22 to maintain the SOC of the secondary battery 22 and perform optimum recovery in accordance with the save mode. be able to.

<Unspecified mode>
The maintenance operation and the recovery process in the non-designated mode, that is, the mode that is neither the charge mode nor the save mode will be described with reference to FIGS. 6 and 7 together with FIG. In this non-designation mode, the recovery process and the recovery process under the output reduction control are the same as those in the save mode, and will be described here with reference to FIG.

(Step S41)
The control device 50 refers to the SOC of the secondary battery 22 using the control unit 25.

(Step S42)
The control device 50 confirms whether the selection of the mode selection switch 52 is the charge mode or the save mode. If the mode selection switch 52 is not the charge mode or the save mode, the control device 50 proceeds to step S43. move on. In this non-designation mode, the minimum SOC that does not run out is stored as a saved SOC, and the subsequent control is performed so as to maintain this saved SOC.

(Step S43)
The control device 50 confirms whether or not the voltage drop width from the previous recovery process is larger than the predetermined voltage width, or whether or not the elapsed time from the previous recovery process is larger than the predetermined time. If the voltage drop width is larger than the predetermined voltage width, or if the elapsed time from the previous recovery process is longer than the predetermined time, the process proceeds to step S44. Otherwise, that is, the voltage drop width is equal to or smaller than the predetermined voltage width. Alternatively, if the elapsed time is equal to or shorter than the predetermined time, the process proceeds to step S47. The voltage drop width and elapsed time here are as described in step S3 above.

(Step S44)
The control device 50 checks the power at 0.2V, the current drive power, and the current received power of the secondary battery 22, and if [(0.2V power−drive power) <accepted power], step S45. If [(0.2V power-drive power) ≧ accepted power], the process proceeds to step S46. That is, it is determined whether or not there is a capacity for charging the secondary battery 22. The power at 0.2 V, the drive power, and the received power here are also as described in step S4 above.

(Steps S45 and S46)
If there is a capacity capable of charging the secondary battery 22, a recovery process is performed in step S45, and if there is no capacity capable of charging the secondary battery 22, a recovery process under the output reduction control is performed in step S46. Is called. The recovery process and the recovery process under the output reduction control will be described later with reference to steps S31 to S36 in FIG.

(Step S47)
After completion of the recovery process or the recovery process under the output reduction control, the maintenance operation, that is, the SOC of the secondary battery 22 is maintained at the saved SOC, that is, the SOC is maintained at the minimum SOC (for example, 30%) that does not run out of electricity. Thus, the fuel cell 11 is operated.

  Then, the recovery process and the recovery process under the output reduction control are performed by the same procedure as that shown in FIG. The recovery process under the output reduction control is the same procedure as the recovery process except for the output reduction control described above.

(Step S31)
The control device 50 refers to the cell voltage of the fuel cell 11 at the time of predetermined current power generation. Specifically, the current fuel cell 11 performs the same power generation as the predetermined current power generation (see step S36 described later), the cell voltage at the time of the power generation is measured by the voltage sensor 11c, and is determined as the current cell voltage. This will be described with reference to FIG. 7. The predetermined current generation C2 is first performed, and the current cell voltage is obtained. The predetermined current here is also as described in step S11 above.

(Step S32)
If the voltage obtained by subtracting the previous cell voltage from the current cell voltage is less than 0, the control device 50 proceeds to step S33, and if it is greater than or equal to 0, ends the recovery process. Here, the same process as step S12 described above is performed, and it is determined whether or not the recovery process of the fuel cell 11 is necessary by checking the current cell voltage, and the current cell voltage is the previous cell voltage (predetermined). If the voltage becomes higher than the (voltage), it is determined that the recovery is complete.

(Step S33)
Similar to step S44 described above, the control device 50 confirms the power at 0.2V, the current drive power, and the current received power of the secondary battery 22, and [(0.2V power−drive power) <accepted. If [Power], the process proceeds to step S34, and if [(0.2 V power-drive power) ≧ accepted power], the process proceeds to return. That is, also here, it is determined whether or not there is a capacity for charging the secondary battery 22.

(Step S34)
The control device 50 confirms the current SOC of the secondary battery 22, and when [current SOC ≦ (save SOC−recovered SOC / 2)], the control device 50 proceeds to step S35, otherwise, that is, [current SOC. If> (save SOC-recovery SOC / 2)], the process proceeds to return. The recovery SOC is estimated by subtracting the current drive power amount from the previous or immediately previous 0.2V power generation. Further, the SOC and the electric energy may be average values for a predetermined time.

(Step S35; recovery means)
The control device 50 performs 0.2V power generation in the fuel cell 11 to recover the deterioration of the fuel cell 11. At this time, not only the deterioration of the fuel cell 11 is recovered, but also the output from the fuel cell 11 is increased. As a result, the secondary battery 22 is also charged, so that the SOC of the secondary battery 22 is obtained. However, in this non-designated mode, it is necessary to suppress the fluctuation of the SOC, so that the 0.2V power generation is performed during the predetermined power generation time in which the SOC increases by the recovery SOC described above. Become. Moreover, about 0.2V here is as having described in above-mentioned step S14, and can be changed suitably.

  Step S34 → S35 described above will be described with reference to FIG. 7. When the saved SOC is 30% and the recovery SOC is 4%, when the current SOC is 28% or less, the process proceeds to step S35, and 0.2V Power generation is started, and by performing 0.2 V power generation for the predetermined power generation time, the recovery SOC = 4% is charged, and the current SOC is charged to 32%.

(Step S36; confirmation means)
The control device 50 performs predetermined current power generation in the fuel cell 11. In such power generation at a predetermined current, the recovery of the fuel cell 11 is confirmed by measuring the cell voltage of the fuel cell 11 with the voltage sensor 11c. After the predetermined current generation, steps S31 to S36 are repeated until the condition of step S32 is satisfied, and recovery of deterioration of the fuel cell 11 is performed. Note that the predetermined current power generation here is not a large amount of charge to the secondary battery 22 as described in step S15 above.

  Steps S35 and S36 described above will be described with reference to FIG. 7. In the non-designation mode, if it is determined that the recovery process is necessary, the 0.2V power generation C1 and the predetermined current power generation C2 are determined until it is determined that the recovery is completed. Are performed alternately. Here, since it is necessary to maintain the SOC of the secondary battery 22 at the save SOC, 0.2V power generation C1 is intermittently performed as in the save mode. That is, while suppressing fluctuations in the SOC of the secondary battery 22, 0.2V power generation C1 and predetermined current power generation C2 are alternately performed, and 0.2V power generation C1 is intermittently performed.

  Even in the non-designation mode, the interval between the 0.2V power generation C1 and the predetermined current power generation C2 changes according to the magnitude of the drive power currently used, and the drive power is large (the required output of the drive motor 24 is If it is large), the interval becomes short, and if the drive power is small (the required output of the drive motor 24 is small), the interval becomes long. Then, the cell voltage in the predetermined current power generation C2 rises with the implementation of 0.2V power generation C1, as shown by the dotted arrow in FIG. 7, and the recovery ends when the current cell voltage becomes equal to or higher than the previous cell voltage. It has become.

  After completion of recovery, normal maintenance operation is performed as described in step S47 above. Referring to FIG. 7, the maintenance operation C3 is performed after the end of the recovery process by the 0.2V power generation C1 and the power generation C2 at a predetermined current, and here, the SOC of the secondary battery 22 is maintained at 30%. Thus, the operation of the fuel cell 11 is performed.

  The above-described 0.2V power generation C1 and the predetermined current power generation C2 are preferably performed after the above-described output reduction control is performed, particularly when the secondary battery 22 cannot accept charging.

  As described above, in the non-designation mode, the recovery process is started immediately after the start of the mode, and the recovery process is performed while suppressing the fluctuation of the SOC, thereby ensuring the amount of charge in the plug-in and the fuel cell. 11 power generation efficiency can be improved. In this way, the electric power generated when recovering the deterioration of the fuel cell 11 is used for charging the secondary battery 22, and the SOC of the secondary battery 22 is maintained, and an optimal recovery in accordance with the non-designated mode is performed. It can be carried out.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a fuel cell system equipped with a secondary battery, and not only a fuel cell vehicle but also all fuel cells equipped with a secondary battery such as an aircraft fuel cell system and a stationary fuel cell system. Applicable to the system.

11 Fuel cell 22 Secondary battery 25 Control unit 50 Control device 52 Mode selection switch

Claims (6)

A fuel cell;
A secondary battery that is charged by electric power supplied from the fuel cell;
Recovery means for generating the fuel cell at a voltage lower than the voltage at the time of charging and performing recovery processing of the fuel cell;
Confirmation means for generating the fuel cell at a current lower than the current at the time of charging and confirming the voltage of the fuel cell;
A fuel cell system comprising control means for alternately executing the recovery means and the confirmation means during the charging. The fuel cell system according to claim 1, wherein
A selection means for selecting a first mode for increasing a charging rate of the secondary battery as an operation mode of charging from the fuel cell to the secondary battery;
The control means performs the recovery means and the confirmation means alternately before the charging of the secondary battery when the first mode is selected by the selection means. Battery system. The fuel cell system according to claim 2, wherein
The fuel cell system, wherein the control means continuously performs the recovery means and the confirmation means alternately. In the fuel cell system according to claim 2 or 3,
The selection means has a second mode for maintaining the charging rate of the secondary battery as the operation mode,
The control means intermittently implements the recovery means so that the charging rate of the secondary battery is maintained when the second mode is selected by the selection means. system. In the fuel cell system according to any one of claims 1 to 4,
The control means ends the alternate implementation of the recovery means and the confirmation means when the voltage of the fuel cell confirmed by the confirmation means exceeds a predetermined voltage. In the fuel cell system according to any one of claims 1 to 5,
Supply amount adjusting means for adjusting the supply amounts of fuel gas and oxidizing gas supplied to the fuel cell, temperature adjusting means for adjusting the temperature of the fuel cell, and humidity adjustment for adjusting the humidity of the fuel gas and the oxidizing gas Having at least one of the means,
When the recovery means and the confirmation means are implemented, the control means lowers the supply amounts of the fuel gas and the oxidant gas from before the adjustment by the supply amount adjustment means, and the temperature adjustment means reduces the supply amount of the fuel cell. At least one of raising the temperature from before the adjustment and lowering the humidity of the fuel gas and the oxidizing gas from before the adjustment by the humidity adjusting means is performed, and the internal resistance of the fuel cell is set before the implementation. A fuel cell system characterized in that the internal resistance of the fuel cell system is higher.

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