JP3882671B2 - Control device and control method for fuel cell system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a fuel cell system.
[0002]
[Prior art]
Japanese Patent Application No. 2000-369141 filed on December 4, 2000 by the applicant of the present application with the Japan Patent Office is a fuel cell capable of always realizing sufficient power supply for a load whose power used varies. As a system, when the load of the load circuit fluctuates at a predetermined rate of change, the power storage unit and the surplus load power amount to be supplied from the fuel cell to the load circuit are set, and the output power of the power storage unit and the power storage unit are set. When the input possible power that can be stored by input is calculated and the power difference between the marginal load power and the output possible power is larger than the input possible power, power generation is performed so that the input possible power becomes the charging power of the power storage unit. And a fuel cell system that controls the flow rate or pressure of the gas supplied to the fuel cell so that the insufficient power obtained by subtracting the input power and output power from the surplus load power can always be generated. The controller filed.
[0003]
[Problems to be solved by the invention]
However, in the present invention, the power value to be compensated for the power required at the time of maximum acceleration is calculated as the surplus load power, and the surplus load power is always set to compensate for the power required at the time of maximum acceleration. When calculated, a great amount of supply gas must be supplied to the fuel cell. Therefore, there is a problem that the power consumption of a device that supplies a supply gas such as a compressor or a pump increases, and the electrical efficiency of the fuel cell system deteriorates. Further, in the case where the excessive amount of the supplied gas is discharged to the outside of the system, the pure water (water vapor) contained in the gas is discharged to the outside of the system together with the gas, so that the fuel cell system There is a problem that the water balance of the system deteriorates due to a decrease in the amount of pure water that is held by the system.
[0004]
In view of such problems, an object of the present invention is to reduce the amount of pure water in the fuel cell system without deteriorating the electrical efficiency of the fuel cell system and to a load in which the power used varies. Another object of the present invention is to provide a control device for a fuel cell system that can always provide sufficient power supply.
[0005]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a fuel cell, a load unit that is driven by power generated by the fuel cell being supplied to a load circuit, a power storage unit that stores the generated power from the fuel cell, and a load of the load circuit. Means for calculating a surplus load power supplied from the fuel cell and the power storage unit to the load circuit when fluctuating at a predetermined speed; Pure water content of fuel cell system According to the present invention, there is provided a control device for a fuel cell system comprising means for correcting according to the above.
[0006]
A second invention is characterized in that, in the first invention, the marginal load power is controlled according to input / output possible power of the power storage unit and a target power generation amount of the fuel cell.
[0010]
Third invention In the first invention, the marginal load power correction means detects the amount of pure water in the fuel cell system and corrects the marginal load power to decrease when the amount of pure water decreases. It is characterized by being.
[0011]
4th invention In the first invention, the marginal load power correction means is a means for correcting the marginal load power so as to decrease when a decrease in the pure water amount of the fuel cell system is expected. Features.
[0013]
5th invention Is 1st to 4th In any one of the inventions, the marginal load power is set based on the required power at the maximum acceleration of the vehicle.
[0014]
6th invention Is a power storage unit that stores the generated power of the fuel cell when the load of the load unit driven by the generated power of the fuel cell fluctuates at a predetermined speed, and the fuel cell Load circuit of the load section Set the surplus load power supplied to the Depending on the amount of pure water in the fuel cell system A control method of a fuel cell system, wherein correction is performed.
[0015]
【The invention's effect】
First or 6 In this invention, at least one of the fuel gas and the oxidant gas supplied to the fuel cell is humidified with pure water and generated by the fuel cell, and the generated power is supplied to the load circuit to drive the load. , And supplies the generated power from the fuel cell to the power storage unit. When the load of the load circuit fluctuates at a predetermined speed, the margin load power supplied from the power storage unit and the fuel cell to the load circuit is set, and the margin load is determined based on the input power to the power storage unit. When the power difference between the power and the outputable power of the power storage unit becomes large, the target generated power of the fuel cell is calculated so that the inputable power becomes the charging power of the power storage unit, and the margin load The flow rate or pressure of the supply gas to the fuel cell is controlled so that the insufficient power obtained by subtracting the input possible power and the output possible power from the power can always be generated.
[0016]
In the control apparatus for a fuel cell system according to the present invention, the marginal load power is corrected.
[0017]
As a result, sufficient power supply can always be realized for loads with varying power consumption without deteriorating the electrical efficiency of the fuel cell system and without reducing the amount of pure water in the fuel cell system. Can do.
[0018]
In the second invention, the marginal load power is controlled according to the input / output possible power of the power storage unit and the target power generation amount of the fuel cell. Sufficient power supply can always be realized.
[0022]
Third invention Then, the amount of the pure water of the fuel cell system is detected, and when the amount of pure water decreases, correction is made to decrease the marginal load power, so the amount of supply gas corresponding to the insufficient power And the amount of pure water discharged outside the system can be reduced. As a result, sufficient power supply can always be realized for a load whose power consumption varies without reducing the amount of pure water in the fuel cell system.
[0023]
4th invention In this case, when the decrease in the amount of pure water in the fuel cell system is expected, correction is made so as to decrease the surplus load power, so that the amount of supply gas corresponding to the insufficient power can be decreased. The amount of pure water released outside the system can be reduced. Thereby, sufficient power supply can always be realized with respect to the load in which the used power fluctuates without further reducing the amount of pure water in the fuel cell system.
[0025]
5th invention In this case, since the surplus load power is set based on the power required at the maximum acceleration of the vehicle, the power generation performance of the fuel cell can be easily set.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an example of the configuration of a fuel cell system to which the present invention is applied.
[0027]
The fuel cell stack 1 of this fuel cell system is composed of, for example, a plurality of fuel cell structures in which a fuel cell structure in which an oxidant electrode and a fuel electrode are provided with a solid polymer electrolyte membrane interposed therebetween is sandwiched by separators. The fuel cell stack 1 generates power by supplying air containing oxygen as an oxidant gas to the oxidant electrode side and supplying hydrogen gas as a fuel gas to the fuel electrode side. Supplied to the drive source.
[0028]
The fuel cell stack 1 is supplied with hydrogen gas in the fuel tank 2 at a predetermined pressure by the action of the pressure control valve 3, and is supplied with air as an oxidant gas by a compressor 4 driven by a motor 5. Generates a reaction and generates electricity. The pressure of the air supplied here is controlled by a pressure control valve 6 installed in an exhaust pipe from which exhaust air is exhausted.
[0029]
The electric power generated by the fuel cell stack 1 is supplied to a battery 8 as a power storage unit and, for example, a motor 9 as a load unit. The power supply to the motor 9 and the battery 8 is controlled by the power control unit 7.
[0030]
The operation of the fuel cell system is controlled by the control unit 10. The accelerator operation amount information and the vehicle speed information are input to the control unit 10, and based on these, the target driving force and the target power generation amount of the vehicle are calculated. The pressure control valve 3 has an opening control signal S1, the motor 5 that drives the compressor 4 has a driving force control signal S2, the pressure control valve 6 has an opening control signal S3, and power control is performed. The power control signal S4 is transmitted to the unit 7, and the driving force control signal S5 is transmitted to the motor 9.
[0031]
The electric power control unit 7 takes out electric power from the fuel cell stack 1 in accordance with a control signal S4 from the control unit 10 and supplies the electric power to the motor 9 and the battery 8. When the amount of power supplied from the power control unit 7 generated by the fuel cell stack 1 is larger than the amount of power consumed by the motor 9, the battery 8 charges the surplus power from the difference between the fuel cell stack 1 as charging power. When the amount of power supplied from the power control unit 7 is smaller than the amount of power consumed by the motor 9, the battery 8 supplies power to the motor 9 to supplement the motor 9 by the shortage. To do.
[0032]
FIG. 2 is a block diagram illustrating a functional configuration of the control unit 10.
[0033]
The control unit 10 includes a required load calculation unit 21 to which accelerator operation amount information and vehicle speed information are input, battery temperature information from a battery sensor (not shown) that detects the state of the battery 8, and a charge level of the battery 8 (hereinafter, Input / output possible power calculation unit 22 to which SOC information indicating SOC is input, and margin load power calculation unit 23 that calculates a power value to be compensated for the power required for the vehicle in motor 9 is provided. .
[0034]
Furthermore, the control unit 10 includes a target charge amount calculation unit 24 that performs calculation using information from the input / output possible power calculation unit 22 and the marginal load power storage unit 23, and a target fuel cell (hereinafter referred to as FC) margin. From the power calculation unit 25, the auxiliary machine power consumption calculation unit 26 that calculates the power consumption of each part of the fuel cell system, the required load calculation unit 21, the target charge amount calculation unit 24, and the auxiliary machine power consumption calculation unit 26 A target power generation amount calculation unit 27 that performs calculation using information, and a supply gas amount control unit 28 that performs calculation using information from the target power generation amount calculation unit 27 and the target FC margin power calculation unit 25 are provided.
[0035]
The required load calculation unit 21 calculates the required load power necessary for driving the motor 9 based on the accelerator operation amount information and the vehicle speed information. The required load calculation unit 21 outputs the calculated required load power to the target power generation amount calculation unit 27 as an output signal S11.
[0036]
The input / output possible power calculation unit 22 is based on the battery temperature and the SOC information, the input possible power information indicating the power value that can be stored in the battery 8, and the output possible power that indicates the power value that can be output from the battery 8 to the motor 9. The information is calculated, and the calculated input power is output to the target charge amount calculation unit 24 and the target FC margin power calculation unit 25 as the output signal S14 and the output possible power as the output signal S13, respectively.
[0037]
The surplus load power calculation unit 23 calculates a power value to be compensated for the power necessary for driving the vehicle by the motor 9, and uses the surplus load power as an output signal S12 as a target charge amount calculation unit 24 and a target FC margin. The power is output to the power calculator 25.
[0038]
The target charge amount calculation unit 24 calculates the target charge amount generated by the fuel cell stack 1 and accumulated in the battery 8 based on the output signals S12, S13, and S14. The target charge amount calculation unit 24 determines the target charge amount so that the charge power approaches the surplus load power within the range of the input allowable power, and uses the determined target charge power as the output signal S16 as the target power generation amount calculation unit 27. Output to.
[0039]
Based on the output signals S12, S13, and S14, the target FC margin power calculator 25 calculates a target FC margin power that can be instantaneously extracted from the fuel cell stack 1 and supplied to the motor 9, and this target FC margin power is calculated. Is output to the supply gas amount control unit 28 as an output signal S17.
[0040]
The auxiliary machine power consumption calculation unit 26 calculates the amount of power consumed by the auxiliary machine provided in the fuel cell system, and outputs this auxiliary machine power consumption to the target power generation amount calculation unit 27 as an output signal S15.
[0041]
Based on the output signals S15, S16, and S11, the target power generation amount calculation unit 27 calculates a target power value of the power generated by the fuel cell stack 1, and uses the calculated target power generation power as an output signal S18 to supply the amount of gas. The data is output to the control unit 28.
[0042]
The supply gas amount control unit 28 controls the pressure control valve 3, the motor 5, and the pressure control valve 6 on the basis of the output signals S17 and S18, and controls the pressures of the fuel gas and the oxidant gas supplied to the fuel cell stack 1. The flow rate is controlled to control the power generated by the fuel cell stack 1.
[0043]
FIG. 3 shows a change in the marginal load power corresponding to the change in the required power of the motor 9. Here, the surplus load power means that when the curve A is the amount of power necessary for driving the motor 9 and the power generation response, the fuel cell stack 1 generates power only with the power amount and the power generation response shown in the curve B. When this is not possible, the power generation amount of the fuel cell stack 1 is compensated by supplying a shortage of the power generation amount of the fuel cell stack 1 with respect to the required power generation amount of the motor 9 from the battery 8 to the motor 9 as shown in the curve C, for example. Power. In other words, when the change rate of the required power generation amount of the motor 9 is faster than the power generation responsiveness of the fuel cell stack 1, the required power generation amount becomes insufficient, but the shortage is reduced by the power supplied from the battery 8. By covering this, the required power amount of the motor 9 is compensated. That is, the surplus load power is power for compensating the shaded portion in the figure. The compensation power control method will be described later with reference to FIGS. A specific method for calculating the surplus load power will be described later.
[0044]
FIG. 4 shows the relationship between the output power of the fuel cell stack 1 and the pressure values and flow rates of the fuel gas and oxidant gas supplied to the fuel cell stack 1.
[0045]
In FIG. 4, the minimum required flow rate and the minimum required pressure for extracting electric power from the fuel cell stack 1 are indicated by solid lines. Here, the supply gas amount control unit 28 of the control unit 10 controls each unit so that the control target flow rate and pressure are increased to the flow rate value and pressure value (● in the figure) increased by the target FC surplus power. The electric power extracted from the fuel cell stack 1 is defined as a target power generation amount (◯ in the figure). As a result, the fuel cell stack 1 is in a state where the sum of the target power generation amount and the target FC surplus power can be taken out. When the motor 9 operates at the maximum load and a request for the required load power occurs, the fuel cell stack 1 instantly Control for taking out the target FC surplus power from the stack 1 and supplying it to the motor 9 is performed.
[0046]
On the other hand, when the target FC margin power is set to zero, the supply gas amount control unit 28 controls the motor 5 so that the supply gas has the minimum required flow rate and the minimum required pressure, and reduces the drive amount of the compressor 4. The electric power actually extracted from the fuel cell stack 1 is set as the target power generation amount. In other words, the supply gas amount control unit 28 obtains the control target flow rate and pressure at the point (X1, X2) where the dotted line extending upward from ○ in the drawing and each characteristic intersect when obtaining the output power indicated by ○ in the drawing. To do.
[0047]
FIG. 5 shows changes in output power and input power with respect to the SOC. The power that can be input and the power that can be output also vary depending on the temperature. FIG. 5 shows the characteristics at normal temperature and low temperature.
[0048]
Next, FIG. 6 shows a flowchart showing a processing procedure of power control processing by the control unit 10.
[0049]
When driving the motor 9, the controller 10 first detects in step 1 the temperature of the battery 8 detected by a sensor signal from a battery sensor (not shown) by the input / output possible power calculator 22 constituting the controller 10. Proceed to the next step 2. In the subsequent step 2, the SOC is input to the input / output capable power calculation unit 22 based on the current value and voltage value of the battery 8.
[0050]
Next, in step 3, the input / output possible power calculation unit 22 calculates input power and output power according to the battery temperature and SOC obtained in step 1 and step 2. Here, the input / output possible power calculation unit 22 obtains the input possible power and the output possible power based on the characteristics of the input possible power and the output possible power with respect to the SOC as shown in FIG. 5 and the battery temperature and the SOC.
[0051]
Next, in step 4, the surplus load power calculation unit 23 calculates the surplus load power. The method of calculating the surplus load power will be described in detail with reference to FIG.
[0052]
In the next step 5, the accelerator operation amount information and the vehicle speed information are input to the required load calculation unit 21, and in the next step 6, the request load calculation unit 21 performs a motor operation based on the accelerator operation amount information and the vehicle speed information. The required load power required by 9 is calculated. In step 7, the auxiliary machine power consumption calculator 26 calculates the auxiliary machine power consumption. In the next step 8, the target charge amount calculation unit 24 determines whether or not the marginal load power stored in the marginal load power storage unit 23 is smaller than the outputable power obtained in step 3. The target charge amount calculation unit 24 proceeds to step 9 when the surplus load power is equal to or less than the outputable power, and proceeds to step 11 described later when the surplus load power is larger.
[0053]
When the surplus load power is equal to or less than the output possible power, the target charge amount calculation unit 24 covers the surplus load power with the output possible power as shown in FIG. 7A, and the surplus load power without requiring new charging. Is output to the target power generation amount calculation unit 27, and the process proceeds to step 9.
[0054]
In step 9, the target power generation amount calculation unit 27 outputs the target power generation output signal S18 to the supply gas amount control unit 28 as the required load power obtained in step 6 and advances the process to step 10.
[0055]
In the next step 10, the supply gas amount control unit 28 outputs a control signal for controlling each part based on the output signal S18 of the target generated power from the target power generation amount calculating unit 27 to achieve the target power generation amount. The flow rate and pressure of gas and oxidant gas.
[0056]
On the other hand, when it is determined in step 8 that the surplus load power is larger than the outputable power, the target charge amount calculation unit 24 calculates the shortage of the outputable voltage with respect to the surplus load power in step 11. At this time, the target charge amount calculation unit 24 recognizes the shortage by subtracting the output possible power from the surplus load power.
[0057]
Next, in step 12, the target charge amount calculation unit 24 determines whether or not the shortage calculated in step 11 is smaller than the input power. When it is determined that the shortage is equal to or less than the inputtable power, the process proceeds to step 13, and when it is determined that the shortage is greater than the inputable power, the process proceeds to step 15 described later.
[0058]
In step 13, the target charge amount calculation unit 24 recognizes that there is a relationship shown in FIG. 7B such that the shortage can be covered by charging the input power, and the target charge amount is calculated in step 11 as it is. The shortage that was made.
[0059]
In the next step 14, the target power generation amount calculation unit 27 inputs the required load power obtained in step 6 from the required load calculation unit 21 and the target charge amount obtained in step 13 from the target charge amount calculation unit 24. Then, the process proceeds to step 10 with the power amount obtained by adding the required load power and the target charge amount as the target power generation amount.
[0060]
Next, in step 15 in which it is determined in step 12 that the shortage is greater than the power that can be input, the target charge amount calculation unit 24 is shown in FIG. Recognizing that there is a relationship, input power is set as a target charge amount.
[0061]
In the next step 16, the target power generation amount calculation unit 27 adds the required load power from the request load calculation unit 21 and the target charge amount to obtain the target power generation amount. Here, the target power generation amount calculation unit 27 sets the target power generation amount as a target power generation amount including the auxiliary machine power consumption obtained in Step 7 described above.
[0062]
In the next step 17, the target FC margin power calculation unit 25 obtains the target FC margin power by subtracting the input allowable power from the shortage obtained in step 11, and proceeds to step 10. In the next step 10, the supply gas amount control unit 28 outputs a control signal for controlling each unit based on the target generated power information S18 so that the target power generation amount and the target FC surplus power are obtained as shown in FIG. In addition, the flow rate and pressure of the fuel gas and oxidant gas are used.
[0063]
Next, a margin load power calculation method performed by the margin load power calculation unit (margin load power correction means) 23 in step 4 which is a characteristic part of the present invention will be described with reference to FIG. FIG. 8 is a flowchart for explaining the calculation sequence of the surplus load power.
[0064]
First, in step 101, a reference value M0 for surplus load power is calculated. This reference value is calculated based on map data as shown in FIG. 9 set in advance assuming the electric power required during the maximum acceleration of the vehicle. Next, at step 102, a reduction coefficient km of the surplus load power is calculated. This is calculated by the method shown in FIGS. 10 to 14, and each description will be described later. In step 103, the marginal load power M is calculated by multiplying the reference value M0 by the reduction coefficient km and correcting the reference value M0.
[0065]
FIG. 10 is a diagram for calculating the reduction coefficient km of the surplus load power M, that is, the coefficient for correcting the reference value M0 of the surplus load power, corresponding to the inventions of claims 1 to 5. is there. The power generation response, which is one of the dynamic characteristics of the fuel cell, can be expressed by, for example, a power generation response time constant. The power generation time constant indicates the fuel cell operation state, for example, the flow rates of oxidant gas and fuel gas. Varies with pressure. Therefore, the power generation time constant of the fuel cell is experimentally measured in advance according to the flow rate and pressure, and the reduction coefficient km is set to be small so that the marginal load power M is reduced under the condition where the power generation time constant is small. The map data as shown in FIG. 10 can be created. From this map data, the reduction coefficient km may be calculated according to the flow rate and pressure of the supply gas.
[0066]
As a result, sufficient power supply can always be realized for loads with varying power consumption without deteriorating the electrical efficiency of the fuel cell system and without reducing the amount of pure water in the fuel cell system. Can do.
[0067]
FIG. 11 is a diagram showing a method for calculating the reduction coefficient km of the marginal load power corresponding to the inventions of claims 1 and 6. When the amount of pure water in the fuel cell system decreases with respect to a predetermined reference value, the table data is set in advance so as to have a reduction coefficient km as shown in FIG. . Then, for example, the amount of pure water in the pure water tank is detected, and the reduction coefficient km may be calculated using this table data based on the detected amount of pure water.
[0068]
When the amount of pure water in the fuel cell system is detected and the amount of pure water decreases, the surplus load power is reduced, so that the amount of supply gas corresponding to insufficient power can be reduced and released outside the system. The amount of pure water can be reduced. Therefore, it is possible to always realize sufficient power supply for a load whose power consumption fluctuates without deteriorating the electrical efficiency of the fuel cell system and without reducing the amount of pure water in the fuel cell system. it can.
[0069]
FIG. 12 is a diagram showing an embodiment for calculating a reduction coefficient km of marginal load power corresponding to the inventions of claims 1 and 7. In a fuel cell system using outside air as an oxidant, it is expected that the amount of pure water in the fuel cell system will decrease when the amount of water vapor contained in the outside air is small.
[0070]
Therefore, as shown in FIG. 12, map data is set in advance so as to reduce the surplus load power as the amount of water vapor decreases according to the outside air temperature and the outside air humidity, and the outside air temperature and the outside air humidity are detected, The reduction coefficient km of the surplus load power may be calculated from the map data based on the detected outside air temperature and outside air humidity.
[0071]
FIG. 13 is a diagram showing another embodiment for calculating the reduction coefficient km of the marginal load power corresponding to the inventions of claims 1 and 7. In a fuel cell system, the consumption of pure water may differ depending on the operating pressure, that is, the pressure of the oxidant gas and the fuel gas.
[0072]
Therefore, pure water consumption due to operating pressure is experimentally measured in advance, and the marginal load power is reduced under conditions where the consumption of pure water increases. For example, the reduction coefficient km of the surplus load power may be calculated based on the table data as shown in FIG. 13 based on the operating pressure of the fuel cell.
[0073]
When the decrease in the amount of pure water in the fuel cell system is expected, the surplus load power is reduced, so that the amount of supply gas corresponding to insufficient power can be reduced, and the amount of pure water released outside the system is reduced. Can do. Thereby, sufficient power supply can always be realized with respect to the load in which the used power fluctuates without further reducing the amount of pure water in the fuel cell system.
[0074]
FIG. 14 is another flowchart for explaining the calculation of the surplus load power, corresponding to the first and eighth aspects of the invention.
[0075]
First, in step 201, it is determined whether or not the change amount of the current required load with respect to the required load in the previous calculation is greater than or equal to a predetermined value. That is, it is determined whether the required load has changed suddenly. If it is determined that the required load has not changed suddenly, the routine proceeds to step 202. In step 202, the average value of the required load is calculated, and the average value of the required load is updated based on the current required load. Then, in step 203, the surplus load power is calculated. As in the calculation in step 101, the calculation here is as shown in FIG. 9 set in advance assuming the power required at the maximum acceleration of the vehicle. It is calculated based on simple map data.
[0076]
On the other hand, if it is determined in step 201 that the required load has suddenly changed, the process proceeds to step 204 to determine whether the required load has decreased. If it is determined that the required load has increased, the process proceeds to step 203. If it is determined that the required load has decreased, the process proceeds to step 205. In step 205, the surplus load power is calculated. Here, the surplus load power is calculated by subtracting the current required load from the average value of the required loads.
[0077]
According to the control unit 10 that performs such processing, when the outputable power is smaller than the marginal load power as shown in FIG. 7B, the target charge amount is insufficient when the inputable power is larger than the insufficient power. By setting the target power generation amount so as to make up for the minute, it is possible to keep the surplus load power at any time.
[0078]
For example, as shown in FIG. 15 (a), in the period T1 before the required load of the motor 9 changes, the power generation output of the fuel cell stack 1 exceeds the required load, and as shown in FIG. Charging is in progress. The sum of the target charging power at this time and the output power is the surplus load power. The difference between the fuel cell output (Net) and the fuel cell output (Gross) is the power consumed by the auxiliary machine.
[0079]
Here, as shown in FIG. 15A, the required load fluctuates greatly in the next period T2, the change in the power output from the fuel cell stack 1 is delayed with respect to the change rate of the required load, and the required load is the fuel cell. Even when the total power output from the stack 1 and the battery 8 can be output is exceeded, the target charge amount is set so as to always ensure the surplus load power. Can be supplied. Therefore, according to this fuel cell system, even when the load of the motor 9 fluctuates suddenly, the surplus load power can be supplied to the motor 9, and the power supply can follow the fluctuation of the required load.
[0080]
Further, in this fuel cell system, the power supplied from the battery 8 to the motor 9 can be kept within the power that can be output. Therefore, according to this fuel cell system, the progress of deterioration of the battery 8 can be suppressed.
[0081]
Furthermore, in the period T3 after the end of the load change, the fuel cell system can continue to charge the battery 8 to obtain an SOC that can cover the surplus load power with the output power. Therefore, according to the fuel cell system, when the required load of the motor 9 does not fluctuate, the battery 8 can be charged so that the surplus load power can be supplied.
[0082]
Moreover, according to the control part 10 which performs such a process, as shown in FIG.7 (c), when the output possible power is smaller than the surplus load power, even when the input possible power is smaller than the shortage, It is possible to secure the surplus load power by setting the target FC surplus power.
[0083]
For example, as shown in FIG. 16A, the fuel cell output (Net) exceeds the required load during the period T1 before the load of the motor 9 changes, and is input to the battery 8 as shown in FIG. 16B. Charging is performed below the available power.
[0084]
Here, since the input possible power of the battery 8 is small in the period T1, it is assumed that the surplus load power cannot be covered only by the sum of the charging power and the output possible power in the period T1. On the other hand, in the fuel cell system, the target FC surplus power is set in step 17 so that an excessive power output is always possible. When the required load of the motor 9 increases, the electric power already taken out and the target FC surplus electric power are taken out from the fuel cell stack 1 and the charging power of the battery 8 is supplied to the motor 9.
[0085]
If the load suddenly decreases when the load on the load circuit is approximately constant, the marginal power is calculated so that the sum of the marginal load power and the current load becomes the average value of the load before the load suddenly decreases. Calculate the load power. Therefore, it is possible to prevent the surplus load power from being increased due to the sudden decrease in the load and to increase the supply gas amount unnecessarily, and it is possible to immediately cope with the required load before the sudden decrease. Therefore, while ensuring the operability of the load, without deteriorating the electrical efficiency of the fuel cell system, and without reducing the amount of pure water in the fuel cell system, it is always applied to a load whose power consumption varies. Sufficient power supply can be realized.
[0086]
As described above, in the present invention, by correcting the surplus load power of the fuel cell system according to the operating state of the system, the target FC surplus power can be instantaneously extracted, and the fuel cell stack 1 The period and amount of output shortage can be reduced, and power can be supplied in response to changes in the required load.
[0087]
Further, the marginal load power is corrected so as to prevent the electrical efficiency of the system and the reduction of pure water. In other words, if the power generation response representing the dynamic characteristics of the fuel cell is fast, if a decrease in the amount of pure water is detected, or if a decrease in the amount of pure water is expected, the marginal load power will decrease. The surplus load power is corrected. As a result, the target FC surplus power is reduced, so that the power required to supply the oxidant gas or fuel gas can be reduced, and the pure water is removed from the system together with the supply gas corresponding to the target FC surplus power. Can be prevented from being released.
[0088]
In addition, if the required load is suddenly reduced when the required load is almost constant, the margin is set so that the sum of the marginal load power and the current load is the average value of the required load before the required load is suddenly reduced. Load power is calculated. Therefore, it is possible to prevent the surplus load power from increasing due to the sudden decrease in the required load and the target FC surplus power from increasing. As a result, the power required to supply the oxidant gas or the fuel gas can be reduced, and it is possible to prevent pure water from being discharged outside the system together with the supply gas corresponding to the target FC margin power. .
[0089]
The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea of the present invention.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system to which the present invention is applied.
FIG. 2 is a block diagram showing a functional configuration of a control unit provided in a fuel cell system to which the present invention is applied.
FIG. 3 is a diagram illustrating a relationship between power required by a load unit and marginal load power.
FIG. 4 is a diagram showing the relationship between the output power of the fuel cell stack and the pressure values and flow rates of fuel gas and oxidant gas.
FIG. 5 is a diagram showing a relationship between SOC, outputable power, and inputable power.
FIG. 6 is a flowchart illustrating a processing procedure of power control processing by a control unit.
FIG. 7 (a) shows the relationship between the load required by the load unit and the target power generation amount and output possible power with respect to the surplus load power;
(B) shows the relationship between the load required by the load unit and the target power generation amount, the output possible power and the shortage with respect to the surplus load power,
(C) is a figure which shows the relationship between the load which a load part requests | requires, and the target electric power generation amount with respect to margin load electric power, output possible electric power, target FC margin electric power, and a shortage.
FIG. 8 is a flowchart showing a method for calculating marginal load power.
FIG. 9 is a diagram showing marginal load power set on the assumption of power required during maximum acceleration.
FIG. 10 is a diagram for explaining calculation of a coefficient for reducing the surplus load power according to the flow rate and pressure of the supply gas.
FIG. 11 is a diagram for explaining calculation of a coefficient for reducing the surplus load power according to the amount of pure water.
FIG. 12 is a diagram for explaining calculation of a coefficient for reducing the surplus load power in accordance with the outside air temperature and the outside air humidity.
FIG. 13 is a diagram illustrating calculation of a coefficient for reducing the surplus load power according to the operating pressure of the fuel cell.
FIG. 14 is a flowchart showing a method for calculating marginal load power.
FIG. 15 (a) shows the relationship between the output of the fuel cell stack and the load required by the load section;
(B) is a figure which shows the change of the output possible voltage of an electric power storage part, and an input possible voltage.
FIG. 16 (a) shows the relationship between the output of the fuel cell stack and the load required by the load section;
(B) is another figure which shows the change of the output possible voltage of an electric power storage part, and an input possible voltage.
[Explanation of symbols]
1 Fuel cell stack
2 Fuel tank
3 Pressure control valve
4 Compressor
5 Motor
6 Flow control valve
7 Power controller
8 battery
9 Motor
10 Control unit

Claims (6)

A fuel cell;
A load unit that is driven by the power generated by the fuel cell being supplied to the load circuit;
A power storage unit for storing power generated from the fuel cell;
Means for calculating a surplus load power supplied from the fuel cell and the power storage unit to the load circuit when the load of the load circuit fluctuates at a predetermined speed;
A control device for a fuel cell system, comprising means for correcting the marginal load power according to the amount of pure water of the fuel cell system.   2. The fuel cell system according to claim 1, wherein the surplus load power is controlled according to input / output power of the power storage unit and a target power generation amount of the fuel cell. The margin load power correction means is a means for detecting the amount of pure water in the fuel cell system and correcting the margin load power so as to decrease when the amount of pure water decreases. Item 2. A control device for a fuel cell system according to Item 1. The margin load power correcting unit, when a decrease in the net amount of water of the fuel cell system is anticipated, according to claim 1, characterized in that the means for correcting to reduce the margin load power Control device for fuel cell system. The control apparatus for a fuel cell system according to any one of claims 1 to 4, wherein the marginal load power is set based on a required power at the time of maximum acceleration of the vehicle . A power storage unit that stores the generated power of the fuel cell when the load of the load unit driven by the generated power of the fuel cell fluctuates at a predetermined speed, and a surplus load power that is supplied from the fuel cell to the load circuit of the load unit A control method for a fuel cell system, comprising: setting an amount, and correcting the surplus load power amount according to a pure water amount of the fuel cell system.

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