JP2007250271A - Fuel cell control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control load connection timing at start-up of a fuel cell through improvement of time resolution of cell voltage measurement. <P>SOLUTION: A voltage monitoring device 2 is provided with m pieces of voltage measuring channels and is capable of measuring voltages of all cells of a fuel cell stack 1. At start-up of a fuel cell system, the voltage monitoring device 2 measures voltages of n pieces of cells of the fuel cell stack 1 using n (m>n) pieces of voltage measuring channels out of the m channels, and sends n pieces of cell voltage measured data to a system control device 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell control device, and more particularly to a fuel cell control device capable of speeding up power supply from a fuel cell to a load device when the fuel cell is started.

  A fuel cell system is a device that directly converts chemical energy contained in fuel into electrical energy. In the case of a solid polymer type that is also promising as a power source for automobiles, a fuel cell system is one of a pair of electrodes provided with an electrolyte membrane interposed therebetween. The fuel gas containing hydrogen is supplied to the negative electrode, and the oxidant gas containing oxygen is supplied to the other positive electrode, and the electrode utilizing the following electrochemical reaction generated on the surface of the electrolyte membrane side of these pair of electrodes The electric energy is taken out from.

Anode (negative electrode) reaction: H ₂ → 2H ⁺ + 2e ⁻ (1)
Cathode (positive electrode) reaction: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)
As the fuel gas supplied to the negative electrode, a method of directly supplying from a hydrogen storage device, or a method of supplying a reformed hydrogen-containing gas by reforming a fuel containing hydrogen is known. Examples of the hydrogen storage device include a high-pressure gas tank, a liquefied hydrogen tank, and a hydrogen storage alloy tank. As the fuel containing hydrogen, natural gas, methanol, gasoline or the like can be considered. Air is generally used as the gas supplied to the positive electrode.

  The configuration in which the above electrolyte membrane is sandwiched between electrodes is called a cell (or unit cell), which is the minimum configuration capable of generating power. However, in an actual fuel cell system, in order to increase the voltage for the purpose of improving efficiency, the cell It is often used in the form of a fuel cell stack formed by stacking a plurality of layers. In this case, in order to control the fuel cell in response to deterioration over time, etc., it is necessary to grasp the power generation state for each cell, and there are many fuel cell systems equipped with a device for measuring the voltage of all cells. If the data is transferred in parallel to the control computer, there is a problem that the cost and weight of the control device become enormous.

For such problems, it is known to reduce the cost and weight of a control device by using a bus-type wiring data communication system (for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-168459 (5th page, FIG. 3)

  By the way, if the load is not connected at the time of starting the fuel cell, the voltage of the fuel cell rises to a value close to the theoretical value, and deterioration such as oxidation of the electrode member is accelerated. In addition, if a load is connected to the fuel cell before the start-up, the time during which power is taken out becomes longer, and the fuel efficiency of the fuel cell system is deteriorated. Further, when a load is connected, if there is a cell in which the voltage has not started to rise, the voltage of the cell is reversed (polarization), and electrolysis occurs, resulting in deterioration of the electrode material. Therefore, in order to suppress deterioration of the fuel cell and improve fuel efficiency, it is desirable to control the load connection timing as late as possible at the start of the fuel cell and before the voltage of the fuel cell reaches a value at which deterioration of the electrode member becomes severe. .

  However, since all devices use a single data transfer path in the conventional example, the time resolution of measurement of voltage or the like is degraded due to the limitation of the data transfer rate. For this reason, there is a problem that it is difficult to control the load connection timing when the fuel cell is started.

  In order to solve the above problems, the present invention measures the number of cells whose voltage is measured when the fuel cell is started, with respect to a fuel cell having a configuration of a fuel cell stack in which cells that are the smallest unit capable of generating power are stacked. It is a fuel cell control device whose gist is to reduce it from the possible number.

  In the present invention, at the time of starting the fuel cell, by measuring the voltage of a smaller number of cells than the number of cells that can be measured, the cell voltage measurement time or the cell voltage measurement from the cell voltage measurement means to the determination means Reduces value communication time and cell voltage measurement cycle. As a result, the temporal resolution can be prioritized over the spatial resolution of the cell voltage measurement value in the fuel cell stack, and a high temporal resolution can be realized.

  According to the present invention, the time resolution of the fuel cell voltage measurement is improved, so that the load can be taken out and the voltage of the fuel cell can be lowered before the fuel cell voltage reaches a value at which the deterioration of the fuel cell becomes severe. This makes it possible to suppress the deterioration of the fuel cell. In addition, it is not necessary to connect a load in advance to suppress the deterioration of the fuel cell, and it is possible to reduce the time for taking out the load, so that the fuel consumption of the fuel cell can be improved. There is.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. Although not particularly limited, the following embodiments are fuel cell control devices suitable as power sources for electric vehicles.

  FIG. 1 is a configuration diagram illustrating a configuration of a fuel cell system to which a first embodiment of a control device for a fuel cell according to the present invention is applied.

  In FIG. 1, the fuel cell system includes a fuel cell stack 1 in which a plurality of cells (unit cells) are stacked, and a number of voltage measurement channels equal to the number of cells m. The voltage monitoring device 2 capable of measuring the voltage and the whole fuel cell system are controlled, the cell voltage measured by the voltage monitoring device 2 is received, the cell voltage is determined, and if the cell voltage satisfies the condition, the fuel cell A system control device 3 that connects the stack 1 and a load (not shown) to obtain a current extraction state, a communication controller 12 that connects the voltage monitor device 2 to the bus 4 and enables communication with other devices, and a system control device 3 is connected to the bus 4 to enable communication with other devices, and the bus 4 is provided.

  The communication controllers 12 and 13 and the bus 4 constitute, for example, a controller area network (CAN), and the serial communication protocol defined in ISO 11 898 and ISO 11 519-2 can be used for automobiles. However, an arbitrarily set bus communication standard may be used. The communication controllers 12 and 13 may be incorporated in or integrated with the voltage monitor device 2 and the system control device 3, respectively.

  The fuel cell system is provided with a fuel gas supply system, an oxidant gas supply system, a coolant supply system, and a load device (not shown), and these supply system and load device are also controlled by the system controller 3. Is done.

  The system control device 3 is not particularly limited in the present embodiment, but is constituted by a microprocessor having a CPU, a program ROM, a working RAM, and an input / output interface, and the control contents are stored in the program ROM. This is realized by the CPU executing the control program.

  The voltage monitor device 2 includes two operation modes set by the system control device 3, each of a normal mode and a startup mode. The normal mode is an operation mode in which all of the m voltage measurement channels are used to measure the cell voltages of all the cells of the fuel cell stack 1 and m cell voltage measurement data is transmitted to the system controller 3. .

  The start mode measures the cell voltage of n cells of the fuel cell stack 1 using n (m> n) which are some voltage measurement channels among the m voltage measurement channels, and n This is an operation mode in which the cell voltage measurement data is transmitted to the system control device 3.

  In this start-up mode, the number of channels to be measured is made smaller than the total number of channels, so that the voltage measurement time and / or the voltage measurement data transmission time from the voltage monitor device 2 to the system control device 3 is shortened.

  Next, the control contents in the first embodiment will be described with reference to the control flowchart of FIG. The flowchart of FIG. 2 is called after starting the supply of the fuel gas and the oxidant gas to the fuel cell stack 1 at the start of the fuel cell system, and determines the connection timing of the load device by monitoring the cell voltage. .

  First, in step (hereinafter, step is abbreviated as S) 10, an instruction to set the activation mode is transmitted from the system control device 3 to the voltage monitoring device 2. Next, in S12, the voltage monitoring apparatus 2 that has received this activation mode setting instruction subsequently uses n (m> n) of all m channels to measure the cell voltage of n cells. It becomes. Next, the voltage monitoring device 2 measures n cell voltages of the fuel cell stack 1 using n channels. Next, the voltage monitoring device 2 transmits n pieces of voltage measurement data to the system control device 3 in S16. In S18, the system control device 3 receives n pieces of voltage measurement data. Next, in S <b> 20, the system control device 3 determines whether or not the cell voltage satisfies a condition for connecting the load device, in other words, a condition for starting power extraction from the fuel cell stack 1.

  If it is determined in S20 that the cell voltage does not satisfy the condition, the process returns to S14, and the system controller 3 waits for the voltage monitor device 2 to measure the value of the new cell voltage and transmit it.

  If it is determined in S20 that the cell voltage satisfies the condition, the process proceeds to S22, and an instruction to set the normal mode is transmitted from the system control device 3 to the voltage monitoring device 2. Next, in S24, the voltage monitoring apparatus 2 that has received this normal mode setting instruction enters a normal mode in which the cell voltages of all cells (m) are measured using all m channels. Next, in S26, the system control device 3 connects the fuel cell stack 1 and the load device.

  Next, in S28, the voltage monitoring device 2 measures all cell voltages of the fuel cell stack 1 using all m channels, and in S30, the voltage monitoring device 2 sends m voltage measurement data to the system control device. 3 to send. In S32, the system control device 3 receives m pieces of voltage measurement data. Next, in S34, the system control device 3 calculates, for example, the maximum value, minimum value, standard deviation, etc. of the cell voltage, and determines whether the cell voltage is appropriate based on these values. If the cell voltage is appropriate in the determination of S34, the process returns to S28 for cell voltage monitoring. If the cell voltage is not appropriate in the determination in S34, the process branches to perform well-known cell voltage improvement processing such as change of operating pressure or purge operation in order to recover the cell voltage.

  In the first embodiment, when the fuel cell stack 1 is started, a part of all the channels of the voltage monitor device 2 is used. As a result, when measurement is performed on all channels of the voltage monitoring device 3 as in the prior art, only a cell voltage with low time resolution can be obtained as shown in FIG. Such a cell voltage with high time resolution can be obtained.

  As described above, according to the first embodiment, the time resolution of the fuel cell voltage measurement is improved, so that the load is taken out before the voltage of the fuel cell reaches a value at which the deterioration of the fuel cell becomes severe. It is possible to reduce the voltage of the fuel cell, and the deterioration of the fuel cell can be suppressed. In addition, it is not necessary to connect a load in advance in order to suppress deterioration of the fuel cell, and it is possible to shorten the time for taking out the load, so that the fuel consumption of the fuel cell can be improved.

  FIG. 5 is a configuration diagram illustrating a configuration of a fuel cell system to which a second embodiment of the control device for a fuel cell according to the present invention is applied. The configuration of the second embodiment shown in FIG. 5 is different from the configuration of the first embodiment of FIG. 1 in that the outside air temperature sensor 5 that measures the outside air temperature and the outside air temperature sensor 5 connected to the bus 4 A communication controller 15 that enables communication, a temperature monitor device 6 that measures the temperature of the fuel cell stack 1, and a communication controller 16 that connects the temperature monitor device 6 to the bus 4 to enable communication with other devices. It has been added. Since other configurations are the same as those in FIG. 1, the same components are denoted by the same reference numerals, and redundant description is omitted.

  In the present embodiment, the characteristics of the fuel cell stack 1 are such that the rising start timing of the voltage of the cell in which the voltage rises latest is after the voltage of the cell in which the voltage rises fast becomes constant. Applied.

  In this embodiment, when the fuel cell stack 1 is started, the system control device 3 determines whether or not the fuel cell stack 1 is frozen based on data from the outside air temperature sensor 5 and the temperature monitoring device 6. . For example, if the outside air temperature sensor 5 indicates a freezing point or higher, it is determined that the vehicle is not frozen at all times. If the outside air temperature sensor 5 indicates less than the freezing point, it is determined that it is frozen if any of the plurality of temperature measurement data of the fuel cell stack 1 measured by the temperature monitoring device 6 indicates the freezing point or less.

  When it is determined that freezing has not occurred in the fuel cell stack 1, when the voltage of the cell whose voltage rises the earliest at the start of the fuel cell stack reaches a predetermined value (V1) as shown in FIG. 7 (t1) In addition, a load device is connected to the fuel cell stack 1.

  In addition, when it is determined that the fuel cell stack 1 is frozen in the freezing determination of the system control device 3, the voltage of the single cell that rises the latest when the fuel cell stack starts is a predetermined value (V1). Is reached, the load device is connected to the fuel cell stack 1.

  Next, the contents of control in the second embodiment will be described with reference to the flowcharts of FIGS. The contents described with reference to FIG. 2 in the first embodiment also apply to the second embodiment. FIG. 6 is a detailed explanation of the second embodiment regarding the determination of the cell voltage in S20 of FIG.

  In FIG. 6, when the determination of the cell voltage is started, the system control device 3 first reads the outside air temperature data from the outside air temperature sensor 5 and the temperature data of the fuel cell stack from the temperature monitoring device 6 in S50.

  Next, in S52, the system control device 3 determines whether or not the fuel cell stack is frozen based on these temperature data. When it is determined in S52 that freezing has not occurred (determination is No), the process proceeds to S54, and the cell voltage of the cell whose voltage rises earliest is selected from the already received cell voltage data. Vf. Next, in S58, it is determined whether or not the cell voltage Vf is equal to or higher than a predetermined value V1. If it is determined in S58 that the cell voltage Vf is equal to or greater than the predetermined value V1, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If the cell voltage Vf is less than the predetermined value V1 in the determination of S58, the determination result of the cell voltage is NO, and the process branches to the S14 cell voltage measurement of FIG. 2, and the cell voltage monitoring is continued.

  When it is determined in S52 that freezing has occurred (Yes in determination), the process proceeds to S56, and the cell voltage of the cell whose voltage rises the latest is selected from the already received cell voltage data. Vs. Next, in S60, it is determined whether or not the cell voltage Vs is equal to or higher than a predetermined value V1. If it is determined in S60 that the cell voltage Vs is equal to or higher than the predetermined value V1, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If it is determined in S60 that the cell voltage Vf is less than the predetermined value V1, the determination result of the cell voltage is NO, and the process branches to S14 cell voltage measurement in FIG. 2, and the cell voltage monitoring is continued.

  The predetermined value V1 is a voltage value that does not promote deterioration of the fuel cell stack even when a load is connected to the fuel cell stack when the fuel cell system is started, and is determined experimentally.

  According to the second embodiment described above, the fuel cell stack is frozen in the fuel cell in which the rising of the voltage of the cell in which the voltage rises the latest is after the voltage of the cell in which the voltage rises the fastest becomes constant. In the case where there is not, the load can be taken out before the voltage of the cell whose voltage rises quickly and has a large degree of deterioration reaches a value at which the deterioration becomes severe, thereby suppressing the deterioration of the fuel cell and improving the fuel consumption.

  In addition, when the fuel cell stack is frozen, it is possible to maintain power generation without reversing the voltage in any cell, and to improve fuel efficiency by suppressing deterioration of the fuel cell and shortening the startup time. Can be planned.

  Next, a third embodiment of the present invention will be described. The configuration of the fuel cell system of Example 3 is the same as that of Example 2 shown in FIG. The present embodiment is applied as a characteristic of the fuel cell stack 1 when the cell voltage rising start timing of the latest rising voltage is before the voltage of the cell rising the fastest voltage becomes constant.

  In the third embodiment, when the fuel cell stack is activated, the system control device 3 determines whether or not the fuel cell stack 1 is frozen based on data from the outside air temperature sensor 5 and the temperature monitoring device 6. When it is determined that the fuel cell stack 1 has not been frozen, the voltage of the cell whose voltage rises the latest when the fuel cell starts up reaches the first predetermined value (V2) as shown in FIG. The load device is connected at t2) or when the voltage of the cell whose voltage rises earliest reaches a second predetermined value (V3) higher than the first predetermined value (t3).

  Further, in the determination of freezing of the fuel cell stack 1, when it is determined that the fuel cell stack 1 is frozen, the voltage of the cell whose voltage rises earliest when the fuel cell is started up is the third predetermined value (Va). Or when the voltage of the cell in which the voltage rises the latest reaches a fourth predetermined value (Vb) lower than the third predetermined value, the load device is connected.

  Next, the control content in the third embodiment will be described with reference to the flowcharts of FIGS. The contents described in connection with FIG. 2 in the first embodiment are also applied to the third embodiment. FIG. 8 is a detailed explanation of the third embodiment regarding the determination of the cell voltage in S20 of FIG.

  In FIG. 8, when the determination of the cell voltage is started, the system control device 3 first reads the outside air temperature data from the outside air temperature sensor 5 and the temperature data of the fuel cell stack from the temperature monitoring device 6 in S70.

  Next, in S72, the system control device 3 determines whether or not the fuel cell stack is frozen based on these temperature data. If it is determined in S72 that freezing has not occurred (No), the process proceeds to S74, and the cell voltage of the cell whose voltage rises the latest is selected from the already received cell voltage data, and this cell voltage is selected. Vs. Next, in S76, it is determined whether or not the cell voltage Vs is equal to or higher than a predetermined value V2. If it is determined in S76 that the cell voltage Vs is equal to or greater than the predetermined value V2, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If it is determined in S76 that the cell voltage Vs is less than the predetermined value V2, the process proceeds to S78. In S78, the cell voltage of the cell whose voltage rises earliest is selected from the already received cell voltage data, and this cell voltage is set to Vf. Next, in S80, it is determined whether or not the cell voltage Vf is equal to or higher than a predetermined value V3 (V3> V2). If it is determined in S80 that the cell voltage Vf is equal to or greater than the predetermined value V3, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If it is determined in S80 that the cell voltage Vf is less than the predetermined value V3, the determination result of the cell voltage is NO, and the process branches to S14 cell voltage measurement in FIG. 2, and the cell voltage monitoring is continued.

  When it is determined in S72 that freezing has occurred (Yes in determination), the process proceeds to S82, and the cell voltage of the cell whose voltage rises the earliest is selected from the already received cell voltage data. Vf. Next, in S84, it is determined whether or not the cell voltage Vf is greater than or equal to a predetermined value Va. If it is determined in S84 that the cell voltage Vf is equal to or higher than the predetermined value Va, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If it is determined in S84 that the cell voltage Vf is less than the predetermined value Va, the process proceeds to S86, and the cell voltage of the cell whose voltage rises the latest is selected from the already received cell voltage data, and this cell voltage is set to Vs. Next, in S88, it is determined whether or not the cell voltage Vs is equal to or higher than a predetermined value Vb (Vb <Va). If it is determined in S88 that the cell voltage Vs is equal to or higher than the predetermined value Vb, the determination result of the cell voltage is OK, and the process branches to S22 in FIG. 2 to connect the load device. If the cell voltage Vf is less than the predetermined value Vb in the determination of S88, the determination result of the cell voltage is NO, and the process branches to the S14 cell voltage measurement of FIG. 2, and the cell voltage monitoring is continued.

  The predetermined values V2, V3, Va, and Vb are voltage values that do not promote deterioration of the fuel cell stack even when a load is connected to the fuel cell stack when the fuel cell system is started, and are determined experimentally.

  According to the third embodiment described above, in the fuel cell in which the start of the rising voltage of the cell in which the voltage rises the latest is before the voltage of the cell in which the voltage rises the fastest becomes constant, whether or not the fuel cell stack is frozen Regardless, the voltage is not reversed in any cell, and it becomes possible to take out the load before the voltage of all the cells reaches a value at which the deterioration becomes severe, thereby suppressing the deterioration of the fuel cell and improving the fuel consumption. Can do.

  Needless to say, the above-described Examples 2 and 3 can be applied in the same fuel cell system according to the operating environment of the fuel cell. Therefore, according to the second and third embodiments, it is possible to configure a fuel cell system that suppresses deterioration of the fuel cell and improves fuel efficiency regardless of the possibility of freezing the fuel cell.

  Next, a fourth embodiment of the present invention will be described. Example 4 is an example in which a cell whose voltage rises earliest and a cell whose voltage rises latest is predicted when the fuel cell system is started up, and is combined with Example 2 or Example 3.

  The configuration of the fuel cell system of Example 4 is the same as that of Example 2 shown in FIG. In Example 4, in the control at the time of starting the fuel cell stack, when the introduction direction of the reaction gas in the fuel cell stack and the discharge direction of the surplus reaction gas are the same as the stacking direction of the cells, the flow rate of the reaction gas Considering the distribution, the cell at the reaction gas introduction side end is regarded as the cell whose voltage rises earliest when the fuel cell is started, and the cell at the other end of the reaction gas introduction side is regarded as the cell whose voltage rises the latest when the fuel cell starts. To.

  Further, when the reaction gas introduction direction and the surplus reaction gas discharge direction are opposite to the cell stacking direction, the cell at the reaction gas introduction side end is the cell whose voltage rises the latest at the start of the fuel cell, and The cell at the other end on the reaction gas introduction side is regarded as a cell whose voltage rises earliest when the fuel cell is started.

  According to the present embodiment, it is possible to identify the cell whose voltage rises earliest or the cell whose voltage rises latest at the start of the fuel cell without adding a measuring device or the like, and the voltage of the fuel cell deteriorates the fuel cell. It is possible to take out the load before the value reaches a value where it becomes violent, thereby suppressing deterioration of the fuel cell and improving fuel consumption.

  Next, a fifth embodiment of the present invention will be described. The fifth embodiment is an embodiment that predicts the cell in which the voltage rises the earliest and the cell in which the voltage rises the latest when the fuel cell system is started up, and is combined with the second or third embodiment.

  The configuration of the fuel cell system of Example 5 is the same as that of Example 2 shown in FIG. In Example 5, when the fuel cell is operated with a current larger than a predetermined value (IH) as shown in FIG. 10, the voltage of each cell is measured to estimate the diffusion polarization. In a region where the amount of decrease in voltage with respect to the increase in current on the high current side is large, voltage loss is mainly caused by diffusion polarization, so that diffusion polarization can be estimated from the voltage in that region. In cells with large diffusion polarization, the reaction gas introduction is hindered and the rise of the voltage at startup is delayed, so the cell that rises the earliest at the next startup and the voltage rises the slowest by the estimation formula incorporating this delay Predict cells. In the above estimation of diffusion polarization and voltage rise timing, it is desirable in terms of accuracy to use a prediction formula obtained by correcting a theoretical formula based on a prior experimental result.

  Furthermore, when the fuel cell is operated with a current smaller than the predetermined value (IL) in FIG. 10, the voltage of each cell is measured, and the activation polarization is estimated. In the region where the amount of voltage decrease with respect to the current increase on the low current side is large, the voltage loss is mainly caused by the activation polarization. Therefore, the activation polarization can be estimated from the voltage in that region. A cell having a large activation polarization can be handled as a cell having a slow voltage rise because the voltage rise at the start-up with a small current is small.

  According to the fifth embodiment described above, the influence of the change in the voltage rise of the cell at the start of the fuel cell due to the deterioration of the fuel cell or the difference in the operation history is reduced, The cell in which the voltage rises the latest can be predicted, and the load is taken out before the voltage of the fuel cell reaches a value at which the deterioration of the fuel cell becomes severe, thereby suppressing the deterioration of the fuel cell and improving the fuel consumption.

  Next, a sixth embodiment of the present invention will be described. Example 6 is an example of predicting the cell in which the voltage rises earliest and the cell in which the voltage rises latest when the fuel cell system starts up, and is combined with Example 2 or Example 3.

  The configuration of the fuel cell system of Example 6 is the same as that of Example 2 shown in FIG. In Example 6, the temperature in the fuel cell stack after power generation is stopped is continuously measured. In a cell having a low temperature, liquid water tends to remain in the electrode portion, so that the introduction of the reaction gas is hindered at the next start-up, and the rise of the voltage is delayed. The estimation formula incorporating this delay predicts the cell in which the voltage rises earliest and the cell in which the voltage rises latest at the next start-up.

  According to the sixth embodiment, the influence of the change in the cell voltage rise at the start of the fuel cell due to the deterioration of the fuel cell or the difference in the operation history is reduced, and the cell that rises the earliest at the start of the fuel cell or the latest voltage It is possible to predict the cell at which the fuel cell rises, and to take out the load before the voltage of the fuel cell reaches a value at which the deterioration of the fuel cell becomes severe, thereby suppressing the deterioration of the fuel cell and improving the fuel consumption.

  Next, a seventh embodiment of the present invention will be described. The seventh embodiment is an embodiment that predicts the cell in which the voltage rises earliest and the cell in which the voltage rises the latest when the fuel cell system starts up, and is combined with the second or third embodiment.

  FIG. 11 is a configuration diagram illustrating a configuration of a fuel cell system to which a seventh embodiment of the control device for a fuel cell according to the present invention is applied. The configuration of the seventh embodiment shown in FIG. 11 is in addition to the configuration of the second embodiment of FIG. 5, the cell resistance measuring device 7 that measures the resistance of each cell of the fuel cell stack 1, and the cell resistance measuring device 7 is connected to the bus 4. And a communication controller 17 that enables communication with other devices. Since the cell resistance can be measured by adding a mechanism for applying a weak alternating current to the cell to the voltage monitoring device 2, the voltage monitoring device 2 and the cell resistance measuring device 7 are integrated, and the communication controllers 12, 17 Can also be integrated.

  In Example 7, after the power generation of the fuel cell stack 1 is stopped, the cell resistance is continuously measured by the cell resistance measuring device 7. In a cell with high resistance, the electrolyte membrane is dry, and it takes time to increase the amount of moisture in the membrane that affects the mass transfer in the membrane, so that the voltage rise is delayed at the next startup. The estimation formula incorporating this delay predicts the cell in which the voltage rises earliest and the cell in which the voltage rises latest at the next start-up.

  According to the seventh embodiment described above, the influence of the change in the voltage rise of the cell at the start of the fuel cell due to the deterioration of the fuel cell or the difference in the operation history is reduced, and the cell where the voltage rises earliest at the start of the fuel cell The cell in which the voltage rises the latest can be predicted, and the load is taken out before the voltage of the fuel cell reaches a value at which the deterioration of the fuel cell becomes severe, thereby suppressing the deterioration of the fuel cell and improving the fuel consumption.

  The above Examples 4 to 7 can be applied in any combination in the same fuel cell system, and as a result, the prediction accuracy of the cell in which the voltage rises earliest at the start and the cell in which the voltage rises latest is the highest. Can be improved.

It is a block diagram explaining Example 1 of the control apparatus of the fuel cell which concerns on this invention. 3 is a control flowchart for explaining the operation of the first embodiment. It is a time chart explaining the cell voltage monitor value at the time of starting in a prior art example. It is a time chart explaining the cell voltage monitor value at the time of starting in an Example. It is a block diagram explaining Example 2 of the control apparatus of the fuel cell which concerns on this invention. 6 is a control flowchart for explaining the operation of the second embodiment. It is explanatory drawing of the voltage predetermined value in Example 2. FIG. 10 is a control flowchart for explaining the operation of the third embodiment. It is explanatory drawing of the voltage predetermined value in Example 3. FIG. It is explanatory drawing of the electric current predetermined value in Example 5. FIG. It is a block diagram explaining Example 7 of the control apparatus of the fuel cell which concerns on this invention.

Explanation of symbols

1: Fuel cell stack 2: Voltage monitoring device 3: System control device 4: Bus 5: Outside air temperature sensor 6: Temperature monitoring device 7: Cell resistance measuring device 12, 13, 14, 15, 16, 17: Communication controller

Claims (9)

A fuel cell having a configuration of a fuel cell stack in which cells that are the minimum units capable of generating power are stacked, wherein the number of cells for measuring voltage when starting the fuel cell is reduced from the measurable number. Battery control device. The load is connected when the voltage of a cell whose voltage rises earliest at the start of the fuel cell reaches a predetermined value when it is determined that the fuel cell is not frozen. Fuel cell control device. The load is connected when the voltage of a cell whose voltage rises the latest when the fuel cell starts up reaches a predetermined value when it is determined that the fuel cell is frozen. Item 3. The fuel cell control device according to Item 2. When it is determined that the fuel cell has not been frozen, the voltage of the cell whose voltage rises the latest when the fuel cell starts up reaches the first predetermined value, or the voltage of the cell whose voltage rises the earliest 2. The fuel cell control device according to claim 1, wherein a load is connected when a second predetermined value higher than a predetermined value of 1 is reached. When it is determined that the fuel cell is frozen, the voltage of the cell whose voltage rises earliest when the fuel cell starts up reaches the first predetermined value, or the voltage of the cell whose voltage rises latest is the first 5. The fuel cell control device according to claim 1, wherein a load is connected when a second predetermined value lower than a predetermined value of 1 is reached. When the reaction gas introduction direction and the surplus reaction gas discharge direction are the same as the cell stacking direction, the reaction gas introduction side cell is the cell whose voltage rises earliest when the fuel cell is started, and the reaction gas. When the cell at the other end of the introduction side is regarded as the cell where the voltage rises the latest when the fuel cell starts, the reaction gas is introduced when the introduction direction of the reaction gas and the discharge direction of the surplus reaction gas are opposite to the cell stacking direction. A cell at the introduction side is regarded as a cell whose voltage rises the latest when the fuel cell is started, and a cell at the other end of the reaction gas introduction side is regarded as a cell whose voltage rises the earliest when the fuel cell is started. The fuel cell control device according to claim 5. The cell according to any one of claims 2 to 5, wherein a cell whose voltage rises earliest and a cell whose voltage rises latest are predicted at the start of the fuel cell based on the voltage of the cell during power generation. The fuel cell control device described. Temperature measuring means for measuring the temperature of the fuel cell,
6. The cell according to any one of claims 2 to 5, wherein a cell whose voltage rises earliest and a cell whose voltage rises latest when the fuel cell starts is predicted based on the temperature of the cell after power generation is stopped. The fuel cell control device described in 1. Cell resistance measuring means for measuring the resistance of the cell of the fuel cell;
6. The cell according to any one of claims 2 to 5, wherein the cell whose voltage rises earliest and the cell whose voltage rises latest is predicted when the fuel cell is started based on the resistance of the cell after power generation is stopped. The fuel cell control device described in 1.

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