JP2016119268A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system in which residual pressures in fuel tanks in a plurality of independent subsystems are uniformized with simple configuration.SOLUTION: The fuel cell system includes a subsystem group which comprises a plurality of subsystems 1-1, 1-2, ..., 1-N including: fuel cells 16-1, 16-2, .., 16-N; fuel tanks 12a-1, 12b-1, 12a-2, 12b-2, ..., 12a-N and 12b-N; pressure detection means 13a-1, 13b-1, 13a-2, 13b-2, ..., 13a-N and 13b-N; and output control means 17-1, 17-2, .., 17-N. The fuel cell system further I includes a control device 2 which outputs a signal corresponding to request output to each of the subsystems to all output control means provided in the subsystem group. The control device 2 makes the request output to a first subsystem with a higher residual pressure greater than the request output to a second subsystem with a lower residual pressure between the two subsystems included in the subsystem group.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel cell system including a plurality of subsystems each having a fuel cell and a fuel tank.

  A fuel cell system used in a fuel cell vehicle or the like increases output by providing a plurality of subsystems each having a fuel cell and a fuel tank. Therefore, the fuel cell system can easily cope with a large vehicle such as a bus. In such a fuel cell system, there is a difference in the residual pressure of the fuel tank among a plurality of subsystems due to differences in performance of the fuel cells of each subsystem.

  When filling the fuel gas from the station to the fuel tank, the station gradually raises the supply pressure, detects the pressure when the fuel gas begins to enter, and considers the temperature rise due to adiabatic compression during filling, and fills the target Determine the pressure. For example, when fuel gas is filled in two tanks having a difference in residual pressure, the fuel gas begins to enter only the low-pressure side fuel tank at first. At this time, the pressure of the fuel tank on the high pressure side cannot be detected from the filling port.

  If filling is continued in this state, the fuel gas begins to enter the fuel tank on the high pressure side when the residual pressures of the two fuel tanks become equal, and the residual pressure starts to rise evenly. At this time, the temperature of the fuel tank which was on the low pressure side at the start of filling is higher than that at the start of filling due to adiabatic compression at the time of filling. On the other hand, the temperature of the fuel tank that was on the high pressure side has not increased.

  Therefore, when the residual pressures of the two fuel tanks are equal, the fuel tank that is on the high pressure side has a higher SOC (State Of Charge) because the temperature is lower than the fuel tank that is on the low pressure side. It is in. However, the target filling pressure is determined based on the pressure when the fuel gas begins to enter the fuel tank that was on the low pressure side. Therefore, when the residual pressure of the two fuel tanks reached the target filling pressure, even if the SOC of the fuel tank that was on the low pressure side was set to 100% or less, it was on the high pressure side where the temperature was lower at the same pressure. There is a possibility that the SOC of the fuel tank exceeds 100%.

  As described above, if the fuel gas is filled in a state where the difference in the residual pressure of the fuel tank is generated, the SOC of the fuel tank having a high residual pressure may exceed 100%. Therefore, it is necessary to control the fuel tank residual pressure of each subsystem so that there is no difference in the fuel tank residual pressure among the plurality of subsystems during operation of the fuel cell system.

  If there are multiple fuel tanks in the same system, such as multiple fuel tanks in the same subsystem, the frequency of shut valves provided in the supply lines from each fuel tank remains. The residual pressure can be made uniform by changing the pressure according to the pressure. Specifically, the opening frequency of the shut valve with a high residual pressure in the corresponding fuel tank is set higher than that of the shut valve with a low residual pressure in the corresponding fuel tank, so that the residual fuel is transferred from the fuel tank with a high residual pressure to the fuel cell. Residual pressure is made uniform by supplying more fuel gas than a fuel tank with low pressure.

  However, this method cannot correct the difference in average residual pressure between independent subsystems. In order to equalize the residual pressure in the fuel tank of each subsystem in the same manner, it is necessary to communicate the fuel supply system so that the shut valves of each subsystem can be driven mutually. This complicates the system and increases manufacturing costs. Therefore, another method for equalizing the residual pressure of a plurality of independent subsystems is necessary.

  Patent Document 1 proposes a method of equalizing fuel gas consumption among a plurality of fuel cells by equalizing output currents of a plurality of fuel cells connected in parallel to the fuel gas supply device.

JP 2003-243008 A

  However, in order to equalize the output pressure of multiple subsystems and equalize the residual pressure of each subsystem, the required output to each subsystem is determined in consideration of auxiliary machine power consumption and fuel cell degradation. There is a need. This complicates the system and increases manufacturing costs.

  In view of the above, an object of the present invention is to provide a fuel cell system that equalizes the residual pressure of a fuel tank in a plurality of independent subsystems with a simple configuration.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a fuel cell (16-1, 16-2, ..., 16-N) that outputs electric power by an electrochemical reaction between an oxidant gas and a fuel gas. ) And a fuel tank (12a-1, 12b-1, 12a-2, 12b-2,... 12a-N, 12b-N) that is filled with fuel gas and supplies the filled fuel gas to the fuel cell. Pressure detecting means (13a-1, 13b-1, 13a-2, 13b-2, ..., 13a-N, 13b-N) for detecting the residual pressure of the fuel gas filled in the fuel tank; Output control means (17-1, 17-2,..., 17-N) for controlling the output of the fuel cell in accordance with the input signal, and subsystems (1-1, 1-2,. .., a subsystem group including a plurality of 1-N) and all the subsystem groups include And a control device (2) that outputs a signal corresponding to a required output that is a target value of power to be output to each subsystem included in the subsystem group. The required output correction is performed so that the required output for the first subsystem with the higher residual pressure is larger than the required output for the second subsystem with the lower residual pressure among the two subsystems of the group. It is said.

  According to this, the required output correction for making the required output for the first subsystem larger than the required output for the second subsystem having a lower residual pressure than the first subsystem is performed, and the difference between the required outputs for each subsystem is made. Occurs. Therefore, the fuel consumption of each subsystem can be adjusted with a simple configuration, and the residual pressures of a plurality of independent subsystems can be made uniform.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a block diagram of the fuel cell system in 1st Embodiment. It is a control flow of the control apparatus in 1st Embodiment. It is a graph of the result of having performed correction of demand output in a 1st embodiment. It is a block diagram of the fuel cell system in 2nd Embodiment. It is a calculation flow of the request | requirement output of the control apparatus in 2nd Embodiment. It is a calculation flow of the request | requirement output of the control apparatus in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. The fuel cell system 100 of this embodiment is applied to a so-called fuel cell vehicle, which is a kind of electric vehicle, and supplies electric power to an electric load such as an electric motor for vehicle travel.

  First, the configuration of the fuel cell system 100 will be described with reference to FIG. As shown in FIG. 1, the fuel cell system 100 includes a subsystem group, a control device 2, a fuel filling port 3, a pipe 4, and a fuel filling valve 5, and is connected to a load 6. The load 6 is an electric load composed of a vehicle driving electric motor or the like.

  In FIG. 1, two subsystems belonging to the subsystem group are referred to as subsystems 1-1 and 1-2, respectively. Since the configurations of the subsystem 1-1 and the subsystem 1-2 are the same, the description below will be made by omitting the hyphens below the reference numerals.

  The subsystem 1 outputs power corresponding to a signal from the control device 2 and supplies it to the load 6. The sub-system 1 includes a check valve 11, two fuel tanks 12 a and 12 b, two pressure detection means 13 a and 13 b, two shut valves 14 a and 14 b, and a fuel supply valve 15. The subsystem 1 includes a fuel cell 16, a PCU (Power control unit) 17, and a secondary battery 18. Details of the subsystem 1 will be described later.

The control device 2 calculates a target value _{Ptotal of} electric power output from the entire fuel cell system 100 based on the accelerator opening and the like, and according to the target value _Ptotal and the residual pressure of the fuel tanks 12a and 12b of each subsystem. This is a device for determining a target value of power to be output to each subsystem. The control device 2 includes a well-known microcomputer composed of a CPU, ROM, RAM, and the like and its peripheral circuits.

  The input terminal of the control device 2 is connected to the load 6, the pressure detection means 13a and 13b of each subsystem, an accelerator (not shown), and the like. Further, the input terminal of the control device 2 is connected to auxiliary devices such as a hydrogen pump, an air pump, and a cooling water pump (not shown) arranged around the fuel cell 16 such as a current sensor, a voltage sensor, and a temperature sensor (not shown). Yes. Further, the output terminal of the control device 2 is connected to the shut valves 14a and 14b, the fuel supply valve 15, and the PCU 17 of each subsystem.

  The fuel filling port 3 is connected to the outside of the vehicle, and is used to fill the fuel gas into the fuel tanks 12a and 12b of each subsystem from the outside of the vehicle. A pipe 4 is formed from the fuel filling port 3 toward the inside of the fuel cell system 100, and a fuel filling valve 5 is provided in the pipe 4. The fuel filling valve 5 is open when fuel gas is filled, and is closed otherwise.

  The pipe 4 branches off from the fuel filling port 5 on the side opposite to the fuel filling port 3, and each subsystem is connected to the end of the branched pipe 4.

  Details of the subsystem 1 will be described. As described above, the subsystem 1 includes the check valve 11, the two fuel tanks 12a and 12b, the two pressure detection means 13a and 13b, the two shut valves 14a and 14b, the fuel supply valve 15, the fuel cell 16, and the PCU 17. The secondary battery 18 is provided.

  A check valve 11 of each subsystem is provided in the pipe 4 branched from the end of the fuel filling valve 5. The check valve 11 is used to restrict the flow of the fuel gas sent from the outside of the vehicle to the fuel tanks 12a and 12b through the fuel filling port 3 and the piping 4 in one direction when the fuel gas is filled, and to prevent backflow. Is.

  The pipe 4 branches into two at the tip of the check valve 11. One of the branches is further branched into two, and fuel tanks 12a and 12b are connected to the branches. A fuel cell 16 is connected through a fuel supply valve 15 to the other end of the pipe 4 that branches into two at the end of the check valve 11.

  The fuel tanks 12a and 12b are compressed gas tanks filled with fuel gas. The fuel tanks 12a and 12b are respectively provided with pressure detection means 13a and 13b for detecting the residual pressure of the fuel tanks 12a and 12b.

  Shut valves 14a and 14b are provided at connecting portions between the pipe 4 and the fuel tanks 12a and 12b, respectively. The shut valves 14 a and 14 b are opened when the fuel gas is filled into the fuel tanks 12 a and 12 b and when the fuel gas is supplied from the fuel tanks 12 a and 12 b to the fuel cell 16. When the fuel gas is filled, all the shut valves 14a and 14b provided in all the subsystems 1 are always opened. When supplying the fuel gas, the shut valves 14a and 14b included in one subsystem 1 are opened one by one. The opening frequency of the shut valves 14a and 14b is controlled by the control device 2 according to the residual pressure of the fuel tanks 12a and 12b, and the shut valve having a higher residual pressure in the corresponding fuel tank has a higher opening frequency. Thereby, the residual pressures of the two fuel tanks 12a and 12b in one subsystem 1 are substantially equal to each other. When the fuel gas is supplied, the fuel supply valve 15 is also opened, and the fuel gas moves from the fuel tanks 12a and 12b to the fuel cell 16.

  The fuel cell 16 generates electric energy to be supplied to an electric load such as the load 6 and the secondary battery 18, and a solid polymer electrolyte fuel cell is employed in the present embodiment.

  More specifically, the fuel cell 16 is a fuel cell stack in which a plurality of fuel cell cells 16a as basic units are stacked and electrically connected in series. In each fuel cell 16a, as shown below, electric energy is output by an electrochemical reaction between hydrogen as a fuel gas and air (oxygen) as an oxidant gas.

(Negative electrode side) H ₂ → 2H ⁺ + 2e ⁻
(Positive electrode side) 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
The electric power output from the fuel cell 16 is supplied to the load 6 and the secondary battery 18 via the PCU 17 and used for driving the motor and the like.

  The PCU 17 controls the flow of power from the fuel cell 16 to the secondary battery 18 or from the secondary battery 18 to the fuel cell 16, and can exchange power bidirectionally regardless of the magnitude of the voltage. . Thereby, when the electric power generated from the fuel cell 16 is larger than the electric power required for the load 6, the surplus electric power is stored in the secondary battery 18. When the power generated from the fuel cell 16 is insufficient, the secondary battery 18 outputs power to the PCU 17 to compensate for the power shortage. The PCU 17 is electrically connected to the load 6, converts the electric power generated from the fuel cell 16, and sends it to the load 6. Further, the PCU 17 has a function of controlling the output of the fuel cell 16 by adjusting the magnitude of the electric power extracted from the fuel cell 16, and corresponds to the output control means of the present invention.

Next, the operation of the fuel cell system 100 of the present embodiment will be described with reference to FIG. When the driver performs an accelerator operation or the like, a signal corresponding to the accelerator opening or the like is input to the control device 2. The control device 2 calculates the target value P _{total of the} electric power output from the entire fuel cell system 100 based on the input signal and the magnitude of the load such as the vehicle running electric motor constituting the load 6. Thereafter, the control device 2 outputs requested outputs to the subsystems 1-1 and 1-2 based on inputs from the pressure detection means 13a-1, 13b-1, 13a-2, and 13b-2, that is, the subsystem 1 -1, 1-2 are repeatedly determined as power target values to be output.

  Specifically, it is determined as shown in FIG. The control device 2 first calculates the difference between the residual pressures in the two subsystems 1 based on the inputs from the pressure detection means 13a and 13b, and sets the absolute value of the difference as the pressure difference ΔP. Here, let the average of the residual pressure of the two fuel tanks 12a-1 and 12b-1 with which the subsystem 1-1 is provided be the residual pressure in the subsystem 1-1. Moreover, let the average of the residual pressure of two fuel tanks 12a-2 and 12b-2 with which the subsystem 1-2 is provided be the residual pressure in the subsystem 1-2. Of the two subsystems 1-1 and 1-2, the higher residual pressure corresponds to the first subsystem of the present invention, and the lower residual pressure corresponds to the second subsystem of the present invention.

The control device 2 calculates the required outputs to the subsystems 1-1 and 1-2 using the target value _Ptotal and the pressure difference ΔP. More specifically, in step S1, the half of the target value P _total, the uncorrected required output of the residual pressure to the higher subsystems. In step S2, a correction rate k is calculated based on the pressure difference ΔP. Here, k = k ₀ ΔP.

Here, the correction ratio k ₀ is appropriately set according to the capacity of the fuel tanks 12a and 12b, the maximum pressure, the output performance of the fuel cell 16, and the like. For example, when using the fuel tanks 12a and 12b having a maximum pressure of 70 MPa and the fuel cell 16 having a maximum output of 100 kW, the correction ratio k ₀ is set in advance such that the correction rate is 10% per 1 MPa of the pressure difference. In this case, k ₀ = 0.1 [MPa ⁻¹ ].

In step S <b> 3, the control device 2 limits the range of the correction factor k so that the required output after correction to each subsystem does not exceed the predetermined maximum output P _max of the subsystem or becomes negative. Specifically, the correction factor k is the smallest value among k ₀ ΔP, 1, and k _max . Here, k _max is k at which the required output after correction to the subsystem with the higher residual pressure becomes P _max, and k _max = 2P _max / P _total −1.

In step S4, the controller 2 adds an output obtained by adding the calculated correction factor to the required output before correction to the subsystem with the higher residual pressure, and outputs the output to the subsystem with the higher residual pressure. To do. Further, in step S5, the target value P _total, an output obtained by subtracting the required output of the corrected residual pressure to the higher subsystems, the required output of the residual pressure to the lower subsystem.

Thus, one of the two subsystems 11 and 12, a request output to the higher residual pressure of the fuel tank _{P req1,} the required output towards lower residual pressure when the _{P req2, P req1} = (1 + k) P _total / 2, and P _req2 = (1-k) P _total / 2.

That is, when half of the target value P _total is a required output before correction to each subsystem, P _req1 is obtained by adding a correction factor to the required output before correction, and P _req2 is a value before correction. This is the required output minus the correction factor.

  When the control device 2 determines the request output to the subsystems 1-1 and 1-2, it outputs a signal corresponding to the determined request output to the PCUs 17-1 and 17-2 of the subsystems 1-1 and 1-2. To do. The PCUs 17-1 and 17-2 output the fuel cells 16-1 and 16-2 so that the outputs of the fuel cells 16-1 and 16-2 become equal to the requested output in response to the input from the control device 2. To control.

As described above, in this embodiment, half of the target value _Ptotal is set as the required output before correction to each subsystem, and the residual pressure is obtained by adding the correction factor to the required output before correction to each subsystem. The required output P _req1 to the higher subsystem is used. Further, the output obtained by subtracting the correction rate from the required output before correction for each subsystem is used as the required output P _req2 for the subsystem having the lower residual pressure. For this reason, the subsystem with the higher residual pressure increases the amount of power generation and consumes more fuel gas, so that the residual pressure drops faster than the subsystem with the lower residual pressure. Thereby, the pressure difference ΔP between the two subsystems 1-1 and 1-2 can be reduced, and the residual pressure of each subsystem can be made uniform.

Since P _req1 + P _req2 = P _total , in this embodiment, the residual pressure is adjusted by the above method, and at the same time, the required output of the entire fuel cell system 100 reaches the target value P _total , and the fuel cell Insufficient output of the entire system 100 is suppressed.

  In this embodiment, the range of the correction factor k is limited so that the required output after correction to each subsystem is not negative, but the required output after correction to one subsystem does not become 0 or less. The upper limit of the correction amount may be set in

  In a fuel cell system that has two subsystems and the fuel consumption of one subsystem is larger than the other subsystem, the required output to each subsystem is corrected by the above method, and the required output is not corrected FIG. 3 shows a change in pressure difference in the case.

  As shown in FIG. 3, when there is no pressure difference between the two subsystems in the initial state and the required output is not corrected, the pressure difference between the subsystems increased as the operating time passed. On the other hand, when there is no pressure difference in the initial state and the required output is corrected, the amount of increase in the pressure difference is smaller than when the correction is not performed. In addition, there was a pressure difference in the initial state, and when the required output was corrected, the pressure difference between the subsystems became smaller as the operating time passed. As described above, the required output correction method used in the fuel cell system 100 of the present embodiment can suppress the pressure difference between the subsystems to a certain amount or less.

  When filling the fuel gas from the station to the fuel tank, the station gradually raises the supply pressure, detects the pressure when the fuel gas begins to enter, and considers the temperature rise due to adiabatic compression during filling, and fills the target Determine the pressure. For example, when fuel gas is filled in two tanks having a difference in residual pressure, the fuel gas begins to enter only the low-pressure side fuel tank at first. At this time, the pressure of the fuel tank on the high pressure side cannot be detected from the filling port.

  If filling is continued in this state, the fuel gas begins to enter the fuel tank on the high pressure side when the residual pressures of the two fuel tanks become equal, and the residual pressure starts to rise evenly. At this time, the temperature of the fuel tank which was on the low pressure side at the start of filling is higher than that at the start of filling due to adiabatic compression at the time of filling. On the other hand, the temperature of the fuel tank that was on the high pressure side has not increased.

  Therefore, when the residual pressures of the two fuel tanks become equal, the fuel tank that was on the high pressure side has a higher SOC because the temperature is lower than the fuel tank that was on the low pressure side. However, the target filling pressure is determined based on the pressure when the fuel gas begins to enter the fuel tank that was on the low pressure side. Therefore, when the residual pressure of the two fuel tanks reached the target filling pressure, even if the SOC of the fuel tank that was on the low pressure side was set to 100% or less, it was on the high pressure side where the temperature was lower at the same pressure. There is a possibility that the SOC of the fuel tank exceeds 100%.

  As described above, if the fuel gas is filled in a state where the difference in the residual pressure of the fuel tank is generated, the SOC of the fuel tank having a high residual pressure may exceed 100%. On the other hand, in the present embodiment, during operation of the fuel cell system, the residual pressure of the fuel tank of each subsystem is controlled by the above-described method, and the difference in the residual pressure of the fuel tank occurs among the plurality of subsystems. Was suppressed.

  In the fuel cell system 100 of this embodiment, the required output between the subsystems is made different by determining the required output to each subsystem according to the residual pressure of the fuel tank in each subsystem. For this reason, it is not necessary to consider the power consumption of the auxiliary equipment and the deterioration of the fuel cell 16 when determining the required output. Accordingly, the fuel consumption of each independent subsystem can be adjusted with a simple configuration, the amount of fuel consumed from each fuel tank can be made uniform, and the residual pressure in each fuel tank can be made uniform. In addition, since the configuration is simple, it is possible to reduce the manufacturing cost of the fuel cell system.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the number of subsystems is changed with respect to the first embodiment, and the others are the same as those in the first embodiment. Therefore, only different portions from the first embodiment will be described.

  The fuel cell system 100 of this embodiment includes two or more, more typically three or more subsystems. Let N be the number of subsystems included in the fuel cell system 100 of the present embodiment. However, N is an integer of 2 or more.

  In FIG. 4, N subsystems included in the subsystem group are subsystems 1-1, 1-2,..., 1-N, m is an integer of 1 to N, and each subsystem is Among the configurations provided, the components included in the subsystem 1-m are represented by adding -m to the reference numerals.

  Of the operation of the fuel cell system 100 according to the present embodiment, parts different from the first embodiment will be described with reference to FIGS. The control device 2 of the present embodiment repeatedly determines the required output for each subsystem by repeatedly executing the required output calculation process of FIG.

  When the control device 2 starts the required output calculation process, the control device 2 proceeds to step S11. In step S11, the control device 2 sets all the subsystems 1-1, 1-2,... Proceed to step S12.

  Except for the case where all the subsystems 1-1, 1-2,..., 1-N have the same residual pressure, at least the first subsystem corresponds to the first subsystem of the present invention, and at least the Nth subsystem. This subsystem corresponds to the second subsystem of the present invention. When attention is paid to two subsystems belonging to the subsystem group, if there is a difference in the residual pressure of the fuel tank between them, the higher residual pressure corresponds to the first subsystem of the present invention. The lower one corresponds to the second subsystem of the present invention. In step S12, the control device 2 sets n = 1 and proceeds to step S13.

In step S13, the control device 2 determines a request output to the nth subsystem. Specifically, when the process proceeds to step S13, the control device 2 proceeds to step S21, determines whether n = 1 or not, and proceeds to step S22 if n = 1. In step S22, the control device 2 sets the request output P _req (n) to the n-th subsystem to a value P _total / N obtained by dividing the target value P _total by N, and proceeds to step S24.

If n = 1 is not satisfied in step S21, the control device 2 proceeds to step S23. In step S23, the control device 2 does not correct the required output by subtracting the required output P _req (n) from the target value _Ptotal , which is the sum of the required outputs to the subsystem that corrected the required output. Divide by the number of remaining subsystems. That is, the control device 2 sets P _req (n) = (P _total −ΣP ′ _req ) / (N−n + 1), and proceeds to step S24. Here, ΣP ′ _req represents the sum from P ′ _req (1) to P ′ _req (n−1), and P ′ _req (n) is a request output after correction to the n-th subsystem. is there.

In steps S24 to S27, the controller 2 corrects the required output based on the relationship between the residual pressure of the fuel tank in the nth subsystem and the residual pressure of the fuel tank in the (n + 1) th to Nth subsystems. Determine P ′ _req (n).

  In step S24, the control device 2 subtracts the average of the fuel tank residual pressures in the nth to Nth subsystems from the fuel tank residual pressure P (n) in the nth subsystem to obtain a pressure difference ΔP ( n), and the process proceeds to step S25.

In step S25, the control device 2 calculates the correction factor k based on the pressure difference ΔP (n). Here, k = k ₀ ΔP (n).

Here, the pressure difference ΔP (n) converted into the filling rate of the fuel tank under the reference pressure is defined as the filling rate difference ΔSOC (n), and the correction rate k is 0 per 1% of the filling rate difference ΔSOC (n). The correction ratio k ₀ may be set to be 0.05 or more and 0.30 or less. The reference pressure is, for example, a pressure in a standard state.

After calculating the correction factor k, the control device 2 proceeds to step S26. In step S26, the control device 2 determines that the corrected output outputs P ′ _req (n) to P ′ _req (N) from the nth to the Nth subsystem are the output ranges of the nth to Nth subsystems. The range of the correction factor k is limited so as not to exceed.

Specifically, the request output P ′ _req (n) after correction to the n-th subsystem is 0 or more and P _max or less, and P _total −ΣP ′ _req is 0 or more and (N−n) P _max or less. Thus, the range of the correction factor k is limited. Here, ΣP ′ _req represents the sum from P ′ _req (1) to P ′ _req (n), and P _max is a predetermined maximum output.

As a result, the correction factor k is the smallest of k ₀ ΔP (n), N−n, and k _max . Here, k _max is k at which the required output P ′ _req (n) after correction to the n-th subsystem becomes the maximum output P _max, and k _max = P _max / P _req (n) −1. is there.

The lower limit of the correction factor k is set to _kmin . k _min is k where P _total −ΣP ′ _req = (N−n) P _max, and k _min = (N−n) {1−P _max / P _req (n)}. Here, .SIGMA.P _'req is, P' represents the sum of the _req (1) to P _'req (n).

When the correction factor k is N−n, P ′ _req (n) = (N−n + 1) P _req (n) in step S27 described later, and P _req (n + 1) in step S23 for the n + 1-th subsystem. = 0, and P ′ _req (n + 1) = 0 in step S27. Similarly, P ′ _req (n + 2) to P ′ _req (N) are also zero.

By limiting the range of the correction factor k in this way, the required output after correction for all the subsystems is 0 or more and the maximum output P _max or less.

After limiting the range of the correction factor k, the control device 2 proceeds to step S27. In step S27, the control device 2 corrects the requested output. Specifically, n-th to the subsystem of the corrected required output P _'req a (n), the pre-correction required output _{P req} (n), the correction amount _{kP req} in accordance with the pressure difference [Delta] P (n) Assume that (n) is added. That is, the control device 2 sets P ′ _req (n) to (1 + k) P _req (n).

  After correcting the requested output, the control device 2 proceeds to step S14. The control device 2 adds 1 to n in step S14, and proceeds to step S15. The control device 2 determines whether or not n> N in step S15. If n> N, the request output calculation processing for each subsystem is terminated. If n> N, the process proceeds to step S13. . The control device 2 outputs signals corresponding to the request outputs determined in this way to the PCUs 17-1, 17-2,..., 17-N.

As described above, in the present embodiment, a value obtained by adding the correction factor corresponding to the pressure difference ΔP (n) to the request output P _req (n) before correction to the nth subsystem is obtained as the nth subsystem. The requested output P ′ _req (n) to the system is used. For this reason, the power generation amount of the subsystem having a high residual pressure is increased, and a large amount of fuel gas is consumed. Therefore, the residual pressure is lowered faster than other subsystems having a low residual pressure. Thereby, the pressure difference of a some subsystem can be made small, and the residual pressure of each subsystem can be equalized.

The sum of P ′ _req (1) to P ′ _req (N) is equal to the target value P _total . Thereby, also in the present embodiment, the residual pressure is adjusted by the above method, and at the same time, the required output of the entire fuel cell system 100 reaches the target value _Ptotal , and the output of the entire fuel cell system 100 is insufficient. That is restrained.

  Also in this embodiment, since the required output to each subsystem is determined according to the residual pressure of the fuel tank of each subsystem, the residual pressure of the fuel tank of each subsystem can be made uniform with a simple configuration. . In addition, the manufacturing cost of the fuel cell system can be reduced.

(Other embodiments)
In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  For example, in the first embodiment, each subsystem includes two fuel tanks 12a and 12b. However, each subsystem may include one, or three or more fuel tanks.

  In the first embodiment, the PCU 17 controls the output of the fuel cell 16 in accordance with a signal from the control device 2. However, the control device 2 operates the fuel supply valve 15 based on the required output, and the fuel The output of the fuel cell 16 may be controlled by adjusting the gas supply amount. In this case, the control device 2 and the fuel supply valve 15 correspond to the output control means of the present invention.

In the first and second embodiments, the required output is calculated in order from the subsystem with the highest residual pressure. As a result, if the required output increases for the subsystem with the higher residual pressure, the required output is calculated. The method is not limited to this. For example, processing may be performed in order from the subsystem with the lowest residual pressure. Also, the difference between the average of the residual pressure of the unprocessed subsystem and the residual pressure of each unprocessed subsystem is calculated, and the subsystem with the largest absolute value of the calculated difference is processed among the unprocessed subsystems. May be. In this case, unlike the second embodiment, the pressure difference ΔP (n) may be less than 0, but when the pressure difference ΔP (n) is less than 0, the correction amount kP _req (n) is also less than 0. Become. In the second embodiment, when processing is performed in order from the subsystem having the lowest residual pressure, the correction rate k may be set to the maximum of k ₀ ΔP (n), −1, and k _min in step S26. _{Here, k min is} 'a k to be the _{req = (N-n) P} max, ΣP' P total -ΣP req represents the sum of 'the _req (1) P' P up _req (n) .

Furthermore, by correcting on the basis of other than the target value P _total may be uniform residual pressure in the fuel tank of each subsystem. For example, the correction may be performed based on the accelerator opening input to the fuel cell system 100 or the required current.

Also, in the allowable range of the subsystem, that is, in the range where the required output to the subsystem does not exceed the predetermined maximum output _Pmax , only the subsystem in which the residual pressure of the fuel tank is higher than the average of the residual pressure in all the subsystems. A correction factor k that outputs power may be used.

  The correction rate k may be nonlinear with respect to the pressure differences ΔP and ΔP (n), and the correction rate k may be determined by a map with respect to the pressure differences ΔP and ΔP (n). For example, the correction rate k may be determined in a step shape according to the range of the pressure differences ΔP and ΔP (n). Further, an upper limit and a lower limit of the correction factor k may be provided within a certain range.

Further, the correction factor k may be dynamically changed according to conditions other than the pressure differences ΔP and ΔP (n). For example, when the pressure difference ΔP, ΔP (n) is constant, it may also be the target value P as _{total is} larger correction factor k increases, so as the target value P _{total is} less correction factor k increases May be. The fluctuation amount of the residual pressure subsystem for as the target value P _{total is} less small, it takes time to correct the operation target value P _{total is} less continues. On the other hand, when the target value _Ptotal is large, the correction is also accelerated, but when the fuel cell is operated at a high output, the power consumption of the auxiliary machinery also increases, and the power generation efficiency decreases. Therefore, in a fuel cell system with a lot of low load operation, the correction can be accelerated by making a correction such that k becomes larger as the target value _Ptotal is smaller. Further, in a fuel cell system that is used from a low load to a high load, the correction can be accelerated by increasing the correction factor k as the target value _Ptotal increases.

1-1 Subsystem 2 Control device 12a-1 Fuel tank 13a-1 Pressure detection means 16-1 Fuel cell 17-1 PCU

Claims (10)

A fuel cell (16-1, 16-2, ..., 16-N) that outputs electric power by an electrochemical reaction between an oxidant gas and a fuel gas, and the fuel gas filled with the fuel gas. Of the fuel gas (12a-1, 12b-1, 12a-2, 12b-2,... 12a-N, 12b-N) and the fuel gas filled in the fuel tank. Pressure detecting means (13a-1, 13b-1, 13a-2, 13b-2,..., 13a-N, 13b-N) for detecting the residual pressure, and the fuel cell according to the input signal A plurality of subsystems (1-1, 1-2,..., 1-N) having output control means (17-1, 17-2,..., 17-N) for controlling outputs. Subsystems, and
A control device (2) for outputting a signal corresponding to a required output, which is a target value of power to be output to each subsystem included in the subsystem group, to all output control means included in the subsystem group; Prepared,
The control device outputs the required output for the first subsystem having the higher residual pressure, out of the two subsystems included in the subsystem group, than the required output for the second subsystem having the lower residual pressure. A fuel cell system that performs a required output correction to be increased.   In the required output correction, the control device determines the first sub-system according to a relationship between a residual pressure of the first subsystem and a residual pressure of a subsystem other than the first subsystem in the subsystem group. A correction rate k for the system is determined, and a correction amount obtained by multiplying the required output before correction to the first subsystem by the correction rate k is added to the required output before correction to obtain a required output after correction. The fuel cell system according to claim 1, wherein The subsystem group has N subsystems;
Among the N subsystems, the required output correction for the Nth subsystem from the first subsystem is performed in order,
In the required output correction, the control device determines a difference ΔP () between an average of residual pressures from an integer nth subsystem of 1 to N and an Nth subsystem and a residual pressure of the nth subsystem. 3. The fuel cell system according to claim 2, wherein the correction factor k is determined according to n).   The correction rate k per 1% of ΔSOC (n) obtained by converting the difference ΔP (n) into a difference in filling rate of the fuel tank under a reference pressure is 0.05 or more and 0.30 or less. The fuel cell system according to claim 3.   The fuel cell system according to claim 4, wherein the reference pressure is a pressure in a standard state.   6. The correction factor k increases as the target value of the sum of power output from all subsystems included in the subsystem group increases when the difference ΔP (n) is constant. The fuel cell system according to any one of the above.   6. The correction factor k increases as the target value of the sum of power output from all subsystems included in the subsystem group decreases when the difference ΔP (n) is constant. The fuel cell system according to any one of the above.   8. The fuel cell system according to claim 3, wherein the correction factor k is non-linear with respect to the difference ΔP (n).   9. The correction factor k according to claim 2, wherein the control device determines the correction factor k so that a required output for all subsystems included in the subsystem group is equal to or less than a maximum output of each subsystem. The fuel cell system according to one. The said control apparatus determines the said correction factor k so that the request | requirement output with respect to all the subsystems with which the said subsystem group is set to 0 or more, The one of Claim 2 thru | or 9 characterized by the above-mentioned. Fuel cell system.

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