JP2003217624A - Fuel cell power plant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power plant capable of guaranteeing stabilized output and quality to any change of the actual air flow rate attributable to variance of components of a compressor or the like and changes of the operational conditions by applying the open control based on a standard flow rate map. <P>SOLUTION: A controller 32 estimate the deviation from the standard value of the oxygen flow rate and the oxygen partial pressure of the air fed to a fuel cell 11 with signals of a current sensor 24 and a voltage sensor 25 of the fuel cell 11 as the input. The controller 32 controls the flow rate of the air fed to the fuel cell 11 to be closer to the standard flow rate based on the estimated deviation of the oxygen flow rate and the oxygen partial pressure, and as a result, controls the rotational speed of a motor 2, the opening of flow rate control valves 9 and 10, and the opening of a pressure control valve 21. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power plant used as a power plant or an electric vehicle drive source.

[0002]

2. Description of the Related Art In order to maintain the quality of a fuel cell power plant when it is mass-produced, it is necessary to suppress as much as possible a performance variation due to a component variation during manufacturing or a variation occurring during assembly. Further, when the fuel cell power plant is used as a vehicle drive source, it is required to keep the output of the fuel cell stable even when the oxygen supply amount varies due to a change in atmospheric pressure due to a change in traveling altitude.

As one method for solving such a problem,
For example, as disclosed in Japanese Patent Laid-Open No. 2000-243421, a case in which variations in electric power due to individual differences in fuel cells during manufacturing are detected and control is performed so as to cancel those variations is known as a known example. ing.

[0004]

At present, most of the fuel cell power plants are of the risholm type (twin screw type).
A compressor is used as an air supply source. Although this compressor has a small flow rate variation in the rated operation range, the performance variation in the low flow rate low pressure operation range corresponding to the idle operation range of the fuel cell is large, and it is difficult to suppress the performance variation in that range by quality control during mass production. It is said that.

When the air flow meter detects the amount of air supplied to the fuel cell and feedback control of the air supply is performed, the problem of such variations can be suppressed to some extent. However, in the case of a system that incorporates the standard flow rate map of the compressor and performs open control of the air supply based on it, the specified performance can be obtained by the deviation between the actual flow rate and the standard flow rate. However, there is a problem in that it is not possible to do so, or problems such as water clogging in the fuel cell occur due to an excessively low or excessive air flow rate.

Further, in the case of the system based on the open control using such a standard flow rate map, when the atmospheric pressure change or the like due to the altitude change of the vehicle running position occurs, it is impossible to cope with the change of the situation. was there.

The present invention has been made to solve the above-mentioned conventional problems, and is a part of a compressor or the like in a fuel cell power plant to which a simple air supply control such as an open control based on a standard flow rate map is applied. An object of the present invention is to provide a fuel cell power plant capable of guaranteeing stable output and quality even when the actual air flow rate changes due to variations and changes in operating conditions.

[0008]

The invention according to claim 1 is
To achieve the above object, in a fuel cell power plant that supplies air and hydrogen to a fuel cell to generate electric power, an oxygen flow rate detecting means for detecting a value related to an oxygen flow rate in the fuel cell, and the fuel cell. The oxygen supplied to the fuel cell based on the oxygen partial pressure detecting means for detecting a value related to the oxygen partial pressure in the inside, and the detection signal of at least one of the oxygen flow rate detecting means and the oxygen partial pressure detecting means. Deviation estimating means for estimating the deviation of the oxygen flow rate or oxygen partial pressure from the standard value, and the flow rate of air supplied to the fuel cell based on the deviation of the oxygen flow rate or oxygen partial pressure estimated by the deviation estimating means. The gist of the present invention is to provide a control means for controlling in a direction of approaching the standard flow rate.

To achieve the above object, the invention according to claim 2 is the fuel cell power plant according to claim 1, wherein the oxygen flow rate detecting means is a current detecting means for detecting a current or a current density of the fuel cell. The point is that there is.

In order to achieve the above-mentioned object, the invention according to claim 3 is a fuel cell power plant according to claim 2, wherein a reformer for supplying hydrogen generated by fuel reforming from raw fuel to the fuel cell is provided. A residual raw fuel concentration detecting means for detecting the concentration of raw fuel remaining in the reformer,
The gist is that the residual raw fuel concentration detecting means is also used as the oxygen flow rate detecting means.

In order to achieve the above object, the invention as set forth in claim 4 is, in the fuel cell power plant according to claim 2, a reformer for supplying hydrogen produced by fuel reforming from raw fuel to the fuel cell. And a temperature detecting means for detecting the temperature in the reformer, and the temperature detecting means is used together as the oxygen flow rate detecting means.

In order to achieve the above object, the invention according to claim 5 is the fuel cell power plant according to any one of claims 1 to 4, wherein the oxygen partial pressure detecting means is a voltage of the fuel cell. The gist is that it is a voltage detecting means for detecting

In order to achieve the above object, the invention according to claim 6 is the fuel cell power plant according to any one of claims 1 to 5, wherein the oxygen flow rate is based on a value detected by the oxygen flow rate detecting means. Is greater than or equal to a first predetermined value, and the oxygen partial pressure based on the detection value of the oxygen partial pressure detection means is less than or equal to a second predetermined value, the deviation is less than or equal to a second predetermined value. The gist of the deviation estimating means is to estimate the deviation by applying a flow rate-corrected map in the low flow rate region.

In order to achieve the above object, the invention according to claim 7 is the fuel cell power plant according to any one of claims 1 to 5, wherein the oxygen flow rate is based on the detection value of the oxygen flow rate detecting means. Is greater than or equal to a first predetermined value and the oxygen partial pressure based on the detection value of the oxygen partial pressure detection means is greater than or equal to a second predetermined value, The gist of the deviation estimating means is to estimate the deviation by applying a flow rate-corrected map in the entire flow rate range.

In order to achieve the above object, the invention according to claim 8 is the fuel cell power plant according to any one of claims 1 to 7, wherein the control means is an air supply to the fuel cell power plant. The gist of the invention is to control at least one of the rotation speed changing means of the compressor or the blower as a supply source and the valve opening changing means of the pressure control valve on the fuel cell outlet side.

In order to achieve the above object, the invention according to claim 9 is the fuel cell power plant according to any one of claims 1 to 8, wherein the control means has an upper limit value for the controlled variable depending on conditions. The point is to provide.

In order to achieve the above object, the invention according to claim 10 is the fuel cell power plant according to claim 9, wherein the rotation speed command value of the compressor or the blower changed by the control means is the compressor or the blower. When the rated rotation speed of the electric motor to be driven is exceeded, the gist is to select the rated rotation speed of the electric motor as the upper limit value of the control amount.

In order to achieve the above object, the invention according to claim 11 is the fuel cell power plant according to claim 9, wherein the valve opening command value of the pressure control valve changed by the control means is the maximum valve opening. When the value is above the value or below the valve opening minimum value, the gist is to select the valve maximum opening or the valve minimum opening as the control amount.

In order to achieve the above object, the invention according to claim 12 is the fuel cell power plant according to any one of claims 9 to 11, wherein the control means sets an upper limit value of the controlled variable. It is a gist to provide a performance deterioration notifying means for notifying the driver of the performance deterioration when the performance deterioration of the fuel cell power plant is detected by the driver.

In order to achieve the above object, the invention according to claim 13 is the fuel cell power plant according to any one of claims 1 to 12, wherein the estimation by the deviation estimating means is performed during idle operation. The point is to do.

In order to achieve the above object, the invention according to claim 14 is the fuel cell power plant according to any one of claims 1 to 13, wherein the change in voltage or current of the fuel cell is oxygen flow rate or oxygen. When the cognitive information that is recognized as not due to the change in partial pressure is obtained, the gist is not to perform flow rate correction control.

In order to achieve the above object, a fifteenth aspect of the invention is characterized in that, in the fuel cell power plant according to the fourteenth aspect, the recognition information is hydrogen leak detection.

In order to achieve the above-mentioned object, the sixteenth aspect of the invention is summarized as the fuel cell power plant according to the fourteenth aspect, wherein the recognition information is water clogging in the fuel cell.

In order to achieve the above object, a seventeenth aspect of the present invention is based on the fuel cell power plant according to the fourteenth aspect, wherein the recognition information is abnormality detection of an air control valve.

In order to achieve the above object, the invention as set forth in claim 18 is the fuel cell power plant according to any one of claims 1 to 17, wherein an air supply device for supplying air to the fuel cell is provided. The gist is that it is a Risholm type compressor.

[0026]

According to the invention of claim 1, in a fuel cell power plant for supplying air and hydrogen to a fuel cell to generate electric power, oxygen for detecting a value related to an oxygen flow rate in the fuel cell is detected. Flow rate detection means, oxygen partial pressure detection means for detecting a value related to oxygen partial pressure in the fuel cell, based on the detection signal of at least one of the oxygen flow rate detection means and the oxygen partial pressure detection means, Deviation estimating means for estimating a deviation from the standard value of the oxygen flow rate or oxygen partial pressure of the air being supplied to the fuel cell, and based on the deviation of the oxygen flow rate or oxygen partial pressure estimated by the deviation estimating means, By providing a control means for controlling the flow rate of the air supplied to the fuel cell in the direction of approaching the standard flow rate, the fuel cell using simple control such as open control based on the standard flow rate map is applied. Also in the power plant, there is an effect that it is possible to provide a fuel cell power plant that flexibly responds to changes in the actual air flow rate due to variations in parts and changes in operating conditions and guarantees stable output and quality. .

According to the invention of claim 2, in the invention of claim 1, the oxygen flow rate detecting means is a current detecting means for detecting the current or the current density of the fuel cell. There is an effect that the oxygen flow rate can be detected by a simple method without using a dedicated sensor such as.

According to a third aspect of the present invention, in the second aspect of the present invention, a reformer for supplying hydrogen generated by fuel reforming from raw fuel to the fuel cell, and a residual gas in the reformer. The residual raw fuel concentration detecting means for detecting the concentration of the raw fuel, and the residual raw fuel concentration detecting means is also used as the oxygen flow rate detecting means. If the residual raw fuel concentration rises in the system using, it can be judged that the oxygen flow rate sent to the reformer is insufficient.By using this information together, the detection accuracy of the oxygen flow rate can be determined. The effect is that it can be further increased.

According to a fourth aspect of the present invention, in the second aspect of the invention, a reformer for supplying hydrogen produced by fuel reforming from raw fuel to the fuel cell, and a temperature inside the reformer. Temperature detecting means for detecting the temperature of the partial oxidation reactor in the reformer as the oxygen flow rate detecting means. If the temperature rise of the partial oxidation reactor is insufficient in a system that uses a fuel reformer as the hydrogen supply means, the endothermic reaction, which is a characteristic of the partial oxidation reaction, may occur due to insufficient oxygen flow rate. It can be determined that it is not promoted, and by using this information together, it is possible to further increase the detection accuracy of the oxygen flow rate.

According to a fifth aspect of the invention, in the invention according to any one of the first to fourth aspects, the oxygen partial pressure detecting means is a voltage detecting means for detecting the voltage of the fuel cell. Therefore, there is an effect that the oxygen partial pressure can be detected by a simple method without using a dedicated sensor such as an oxygen partial pressure gauge.

According to a sixth aspect of the invention, in the invention according to any one of the first to fifth aspects, the deviation of the oxygen flow rate from the standard value based on the detection value of the oxygen flow rate detecting means is If the deviation from the standard value of the oxygen partial pressure based on the detection value of the oxygen partial pressure detecting means is equal to or more than the second predetermined value, the deviation estimating means is Since the deviation is estimated by applying the flow rate-corrected map in, it is possible to estimate that the performance variation of the fuel cell is due to the performance variation or deterioration of the compressor by a simple determination method, and By appropriately estimating the actual flow rate, it is possible to appropriately correct the variation in compressor performance or the variation in air flow rate due to deterioration, which contributes to stable performance of the fuel cell power plant. There is an effect that kill.

According to the invention of claim 7, in the invention of any one of claims 1 to 5, the deviation of the oxygen flow rate from the standard value based on the detection value of the oxygen flow rate detecting means is When the deviation from the standard value of the oxygen partial pressure based on the detection value of the oxygen partial pressure detecting means is equal to or larger than the second predetermined value, the deviation estimating means is Since the deviation is estimated by applying the flow rate corrected map in, it is possible to estimate that the variation in the performance of the fuel cell is caused by the environmental condition such as the change in atmospheric pressure by the simple determination method. It is possible to properly correct the variation in air flow rate due to environmental conditions such as atmospheric pressure change by appropriately estimating the actual flow rate according to
This has the effect of contributing to stable performance of the fuel cell power plant.

According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, the control means is a compressor or a blower that is an air supply source to the fuel cell power plant. Since at least one of the rotation speed changing means and the valve opening changing means of the pressure control valve on the fuel cell outlet side is controlled, even when the air flow rate is caused by the performance variation or deterioration of the compressor or the blower, the atmospheric pressure, etc. There is an effect that the flow rate can be flexibly corrected even when it is caused by the environmental conditions.

According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the control means sets an upper limit value for the control amount depending on the conditions. There is an effect that the command value can be prevented from exceeding the allowable value of the fuel cell power plant parts such as the compressor and the valve, and the reliability thereof can be improved.

According to the invention of claim 10, claim 9 is provided.
In the invention described, in the case where the rotation speed command value of the compressor or the blower changed by the control means exceeds the rated rotation speed of the electric motor driving the compressor or the blower, the rated rotation speed of the electric motor is set as the upper limit value of the control amount. Since the selection is made, it is possible to prevent the control command value from exceeding the allowable value of the fuel cell power plant parts such as the compressor and the blower, and it is possible to improve the reliability thereof.

According to the invention of claim 11, claim 9
In the invention described above, when the valve opening command value of the pressure control valve changed by the control means exceeds a valve opening maximum value or falls below a valve opening minimum value, the valve maximum opening or valve minimum opening is set as a control amount. Since the degree is selected, the control command value can be prevented from exceeding the allowable value of the valve opening degree, and the reliability thereof can be improved.

According to the invention of claim 12, claim 9 is provided.
In the invention according to any one of claims 11 to 11, when the driver detects a performance deterioration of the fuel cell power plant due to the control means providing an upper limit value of the controlled variable,
By providing the performance deterioration notifying means for notifying the driver of the performance deterioration, it is possible to reduce the discomfort caused by the performance deterioration.

According to the invention of claim 13, claim 1
In the invention according to any one of claims 12 to 12, since the estimation by the deviation estimating means is performed during the idle operation, it is determined whether the flow rate correction is necessary within a short time after the fuel cell power plant is started. In addition, the correction preparation can be completed, and the subsequent power plant operation can be stably performed.

According to the invention of claim 14, claim 1
In the invention according to any one of claims 13 to 13, when the cognitive information that the change in the voltage or current of the fuel cell is not caused by the change in the oxygen flow rate or the oxygen partial pressure is obtained, the air flow rate is obtained. Since the correction control is not performed, the case where the air flow rate correction is not appropriate can be detected in advance, and the reliability of the fuel cell power plant can be further improved.

According to the invention of claim 15, claim 1
In the invention described in claim 4, since the recognition information is hydrogen leak detection, a case where the air flow rate correction is not appropriate can be detected in advance, and the reliability of the fuel cell power plant can be further enhanced. There is an effect.

According to the invention of claim 16, claim 1
In the invention described in claim 4, since the recognition information is water clogging in the fuel cell, a case where the air flow rate correction is not appropriate can be detected in advance, and the reliability of the fuel cell power plant is further enhanced. There is an effect that can be.

According to the invention of claim 17, claim 1
In the invention described in claim 4, since the recognition information is abnormality detection of the air control valve, it is possible to detect in advance a case where the air flow rate correction is not appropriate, and further improve the reliability of the fuel cell power plant. There is an effect that can be.

According to the invention of claim 18, claim 1
In the invention according to any one of claims 17 to 17, since the air supply device for supplying air to the fuel cell is a Rishorum type compressor, a Rishorum type compressor having a large variation in a low flow rate region is used. Even when it is used, there is an effect that it is possible to accurately correct the flow rate in the low flow rate range and to supply a fuel cell power plant with stable performance by simple open control.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS.
It will be described with reference to FIG. FIG. 1 is a diagram showing a system configuration of an embodiment of a fuel cell power plant according to the present invention, which is a fuel cell plant suitable for a fuel cell vehicle or a hybrid vehicle using a fuel cell as one power source.

In the figure, an air system and a fuel system are mainly shown, and a pure water system, a cooling system and the like are not shown. In the figure, the compressor 1 is driven by an electric motor 2. The rotation speed of the electric motor 2 is controlled by the controller 32 that is the control means, but the power source, the inverter, etc. for driving the electric motor 2 are not shown in this figure.

The compressor 1 takes in outside air from an intake pipe 5 to which an air cleaner 3 and a silencer 4 are connected and sends compressed air to a high pressure pipe 6. The compressed air having a high temperature is cooled by the aftercooler 7, and the microfilter 8
To remove dust. The air that has passed through the microfilter 8 is supplied to the cathode (air electrode) 12 and the reformer 13 of the fuel cell 11 via the flow rate control valves 9 and 10, respectively. The flow rate control valves 9 and 10 respectively include a flow rate sensor 3
0 and 31 are provided.

In addition to air, the reformer 13 is supplied with raw fuel and water from a raw fuel tank 14 and a water tank 15 which store raw fuel such as methanol and gasoline. Raw fuel and water are injected into the reformer 13 by dedicated injectors 16 and 17, respectively. In the reformer 13, the raw fuel and water are reformed into a reformed gas containing hydrogen gas by a steam reaction or the like, and the hydrogen gas generated here is flow control valve 18
Is supplied to the anode (hydrogen electrode) 19 of the fuel cell 11 via the.

In the fuel cell 11, the anode 19 and the cathode 12 are arranged so as to face each other with a solid polymer electrolyte membrane (not shown) in between, and generate electric power and water by supplying air and hydrogen. The exhaust gas from the fuel cell 11 is combustor 20.
And is discharged from the exhaust pipe 23 through the pressure control valve 21 and the silencer 22.

The present power plant includes a current sensor 24 for detecting the output current of the fuel cell 11, a voltage sensor 25 for detecting the output voltage, a pressure loss sensor 29 for detecting the pressure loss in the air passage in the fuel cell 11, and an air sensor. Flow control valve 9,1
0 air flow rate sensors 30 and 31, a hydrogen flow rate sensor 26 mounted near the hydrogen flow rate control valve 18, a temperature sensor 27 for monitoring the temperature of the reformer 13, and a reformer 13.
A residual raw fuel concentration sensor 28 for detecting the residual raw fuel concentration at the latter stage is provided.

The controller 32 is connected to a vehicle speed sensor and an accelerator pedal sensor (not shown), and receives a vehicle speed signal and an accelerator opening signal. Further, a current sensor 24, a voltage sensor 25, a temperature sensor 27, and a residual raw fuel concentration sensor 28 are connected to the controller 32, and signals of these sensors are input to the controller 32.
Estimates the deviation from the standard value of the oxygen flow rate or oxygen partial pressure of the air supplied to the fuel cell. Then, based on the estimated deviation of the oxygen flow rate or oxygen partial pressure, the fuel cell 1
The controller 32 controls the rotation speed of the electric motor 2, the opening degree of the flow rate control valves 9 and 10, the opening degree of the pressure control valve 21, and the like in order to control the flow rate of the air supplied to the unit 1 toward the standard flow rate. To do.

Further, a low speed warning lamp 33 as a performance deterioration notifying means for notifying the driver of performance deterioration and a maintenance required display lamp 34 for notifying the driver of the detection of the abnormality of the fuel cell plant are provided. It is provided on a console that can be easily viewed from, and these are connected so that blinking control can be performed from the controller 32.

In this embodiment, the current sensor 24 is used as the oxygen flow rate detecting means for detecting the value related to the oxygen flow rate in the fuel cell 11, and the oxygen partial pressure for detecting the value related to the oxygen partial pressure in the fuel cell 11 is detected. A voltage sensor 25 as a detection means
Is provided.

Further, the deviation from the standard value of the oxygen flow rate or the oxygen partial pressure of the air supplied to the fuel cell is estimated based on the detection signal of at least one of the oxygen flow rate detecting means and the oxygen partial pressure detecting means. The controller 32 serves as a deviation estimating means and a control means for controlling the flow rate of the air supplied to the fuel cell toward the standard flow rate based on the deviation of the oxygen flow rate or the oxygen partial pressure estimated by the deviation estimating means. Is provided.

Next, the principle of the present invention will be described. First, the reason why the oxygen flow rate and the oxygen partial pressure can be estimated by detecting the output current (hereinafter abbreviated as current) and the output voltage (hereinafter abbreviated as voltage) of the fuel cell will be described.

Generally, in the case of a polymer electrolyte fuel cell,
The pressure difference between the gas pressure containing hydrogen supplied to the anode and the air pressure supplied to the cathode is kept within a predetermined value so as not to exceed the withstand voltage of the electrolyte membrane. The hydrogen partial pressure supplied to the anode is the majority of the supply gas pressure, while the oxygen partial pressure supplied to the cathode is the supply air pressure multiplied by the oxygen ratio in the air. . Since the compounding ratio of hydrogen and oxygen is 2: 1, the output current of the polymer electrolyte fuel cell is controlled by the oxygen flow rate if the anode gas pressure and the cathode gas pressure are controlled to be approximately balanced. It is operating in a state where

Therefore, in the polymer electrolyte fuel cell, the current value is approximately proportional to the oxygen flow rate, and if either the current value or the oxygen flow rate is determined, the other value can be estimated. it can. In the present invention, by utilizing this characteristic, the current value is estimated from the air flow rate, or the air flow rate is estimated from the reverse current value.

Next, let us pay attention to the relationship between current and voltage.
FIG. 2 schematically shows the relationship between the current and the voltage of the polymer electrolyte fuel cell. As the current value increases, the voltage value tends to decrease.

Therefore, as shown in FIG. 2A, when only the oxygen flow rate is decreased, the output current of the fuel cell is A0.
Although the voltage decreases to → A, the voltage increases to V0 (A0) → V0 (A), and the voltage value V0 (A) estimated from the actual current based on the standard characteristics is almost equal to the measured value V (A).

On the other hand, as shown in FIG. 2 (b), when both the oxygen flow rate and the oxygen partial pressure decrease due to the pressure drop due to traveling at high altitudes, etc., the oxygen partial pressure and the output voltage are in a substantially proportional relationship, and therefore the characteristic straight line Shifts downward. Therefore, even if the current drop is the same amount as before (A0 → A), the voltage increase accompanying it was V0 (A0) → V0 (A) before V0 (A0) → V (A) Will stay in. Thus, the presence or absence of a change in the oxygen partial pressure can be detected by checking the change margin of the voltage with respect to the change in the current value.

Next, the reason why the actual flow rate characteristic of the compressor can be estimated from changes in the oxygen flow rate and the oxygen partial pressure under one operating condition will be described. The phenomenon that only the oxygen flow rate (current value) deviates from the standard value is often due to the performance variation or deterioration of the compressor.

Particularly in the case of the Risholm type compressor, FIG.
As shown in (a), there is almost no performance variation in the large flow rate region, but there is a large variation in the small flow rate region, so such a phenomenon easily occurs. However, since the degree of the variation has a constant law at each rotation speed, if the actual flow rate at a certain rotation speed is obtained, the entire actual flow rate characteristic can be estimated from the value.

On the other hand, the phenomenon that both the oxygen flow rate and the oxygen partial pressure change are often due to the change in atmospheric pressure due to running at high altitude. In this case, the actual flow rate characteristic is obtained by uniformly multiplying the standard flow rate characteristic by the actual partial pressure / standard partial pressure as shown in FIG. By making such an assumption, it becomes possible to estimate the actual flow rate characteristic from changes in the oxygen flow rate and oxygen partial pressure under one operating condition.

FIG. 4 is a flow chart showing the procedure for estimating the actual flow rate characteristic in this embodiment. The operating conditions at the time of estimation assume idling. First, step S102
In, a preliminary check is performed on factors that hinder the estimation of the air flow rate, such as hydrogen leakage, valve operation abnormality, water clogging in the fuel cell, and abnormality of air consumption in the reformer. As a result, if any abnormality is detected in step S103, in order to notify the driver in step S104, the inspection required display lamp 34 is turned on, and then the process ends.

Regarding hydrogen leakage, the hydrogen generation amount estimated from the amount of air supplied to the reformer 13, the amount of fuel, and the amount of water is compared with the actual detection value of the hydrogen flow sensor 26.
When the value of the hydrogen flow sensor 26 falls below the expected amount of generation over a predetermined value, it is determined that there is hydrogen leakage.

Further, regarding the valve operation abnormality, the air flow rate estimated from the valve opening command value to the flow rate control valves 9 and 10 and the air flow rate sensors 30 and 31 mounted near the valves 9 and 10 are detected. If the difference exceeds a certain value, it is determined that there is an abnormality. Regarding the water clogging in the fuel cell 11, when the value of the pressure loss sensor 29 exceeds the designated value, it is determined that the water clogging has occurred.

If there is no abnormality in these preliminary checks, the process proceeds to step S106, and the fuel cell current A, the same voltage V, the compressor rotation speed R, and the pressure control valve opening degree θ at idle are input.

In the next step S107, the air flow rate corresponding to the compressor rotation speed R and the pressure control valve opening θ is determined from the built-in air standard flow rate map, and the current value A0 is obtained from the values.
To calculate. In step S108, the calculated current value A0
And the measured current value A are compared, and the absolute value of the difference | A-A
It is determined whether 0 | does not exceed a preset allowable value Acr.

If it is determined in step S108 that the allowable value is not exceeded, it is determined that the estimated air flow rate is a substantially standard value and correction is not necessary, and in step S109 flow rate control based on the standard map is selected. On the other hand, when it is determined that the allowable value is exceeded, in step S111, the voltage V0 (A) when the current value A is taken in the standard state is calculated. Step S11
In step 2, the calculation result V0 (A) is compared with the measured value V (A), and the absolute value of the difference is the preset allowable value Vcr.
To determine whether or not. If it is determined that the absolute value of the difference exceeds the allowable range, step S
Proceeding to 113, a flow rate characteristic map having a deviation from the standard value in the entire flow rate range is selected, and the control described below is performed.

On the other hand, if it is determined in step S112 that the difference is within the allowable range, step S11
5, the flow rate characteristic map having a deviation from the standard value is selected only in the low flow rate region, and the control described later is performed.

Next, a flow for controlling the air flow rate based on the estimated flow rate will be described. FIG. 5 illustrates a control flow when the deviation of the estimated flow rate from the standard value is limited only to the low flow rate range, and FIG. 6 is a flow rate characteristic map for performing flow rate correction in the low rotation speed range of the compressor. Is an example of.

First, in step S122, the target air flow rate Q1 corresponding to the vehicle speed and the accelerator opening is input. Next, in step S123, the compressor rotation speed R1 is calculated from the target air flow rate Q1 based on the estimated flow rate characteristic shown by the broken line in FIG. Then, in step S124, the calculation result R
1 is compared with the allowable rotation speed Rmax of the compressor. If R1 is equal to or higher than Rmax, R1 is set to Rm in step S125.
Perform processing to limit to ax. Finally, step S126
Then, the command value R1 is output and the process returns.

FIGS. 7 and 8 explain the control flow when the deviation of the estimated flow rate from the standard value is over the entire operating range. First, in step S132, the target air flow rate Q2 corresponding to the vehicle speed and the accelerator opening is input. Next, in step S133, as shown in FIG. 8, the compressor rotation speed R2 and the valve opening θ2 of the pressure control valve are determined based on the estimated flow rate characteristic.

When the deviation of the estimated flow rate from the standard value is over the entire operating range, it may be difficult to obtain a predetermined flow rate by controlling only the rotation speed, unlike the case where the deviation is limited to the low flow rate range described above.

For example, in FIG. 8, in order to achieve the target flow rate of Q2, Q2 cannot be achieved even at the maximum rotation speed in the flow rate characteristic in the state of the valve opening θ1.
Therefore, it is necessary to perform cooperative control of the compressor rotation speed and the pressure control valve, such as reducing the valve opening from θ1 to θ2 to increase the pressure and improving the actual flow rate characteristic before determining the rotation speed R2. Become. The combination of the valve opening degree θ2 and the rotation speed R2 is determined so that some evaluation function takes an extreme value, for example, the drive power becomes minimum.

Then, in step S134, the calculated rotation speed R2 is compared with the allowable rotation speed Rmax of the compressor. If R2 is greater than or equal to Rmax, a process of limiting R2 to Rmax is performed in step S135. Step S13
If R2 is less than Rmax in the comparison of step 4, step S1
At 36, the calculated valve opening θ2 is compared with the allowable value θmin. If the valve opening θ2 is equal to or smaller than the allowable value θmin, the allowable value θmin is substituted for θ2 at step S137. Finally, in step S138, the command value R
Output 2 and θ2 and return.

In steps S134 to 138, when the rotational speed R2 or the valve opening θ2 exceeds the allowable range, for example, the driving power is slightly increased from the minimum value (the evaluation function is slightly increased from the extreme value). Control may be performed to correct the rotational speed and the valve opening degree in a deviated state). Further, when the rotational speed or the valve opening is limited to an allowable value (upper limit value) and the power performance of the vehicle deteriorates, a display is provided to inform the driver of the power performance deterioration such as turning on the low speed warning lamp 33. Good.

The above is a description of the embodiment of the present invention, but a supplementary description will be added below. Step S1 in FIG.
In addition to the judgment material in 02, the deviation between the detection temperature of the temperature sensor 27 and the standard temperature, and the deviation of the value of the residual raw fuel concentration sensor 28 in the rear stage of the reformer 13 and the standard value are used as the judgment material. It is possible to judge with high accuracy whether or not the change in the oxygen flow rate is due to the abnormality of the reformer 13.
In a direct hydrogen type fuel cell power plant that does not have the reformer 13, a judgment based on the current value shown in the current value of this embodiment is sufficient.

[Brief description of drawings]

FIG. 1 is a system schematic diagram showing the configuration of an embodiment of a fuel cell plant according to the present invention.

FIG. 2 is a diagram showing current-voltage characteristics in a polymer electrolyte fuel cell.

FIG. 3 is a diagram illustrating a difference in characteristics of estimated air flow rates.

FIG. 4 is a flowchart illustrating air supply control in the embodiment.

FIG. 5 is a flowchart showing an air flow rate control when the deviation between the standard flow rate and the estimated flow rate stays in a low flow rate region.

FIG. 6 is a diagram illustrating determination of a rotation speed of a compressor.

FIG. 7 is a flowchart showing air flow rate control when the deviation between the standard flow rate and the estimated flow rate is over the entire flow rate range.

FIG. 8 is a diagram illustrating how to determine the rotational speed of the compressor and the opening degree of the pressure control valve.

[Explanation of symbols]

1 ... Compressor 2 ... electric motor 9, 10 ... Flow control valve 11 ... Fuel cell 12 ... Cathode 13 ... reformer 14 ... Raw fuel tank 15 ... Water tank 16, 17 ... Injector 18 ... Flow control valve 19 ... Anode 21 ... Pressure regulating valve 24 ... Current sensor (oxygen flow rate detection means) 25 ... Voltage sensor (oxygen partial pressure detection means) 26 ... Hydrogen flow rate sensor 27 ... Temperature sensor 28 ... Residual raw fuel concentration sensor 29 ... Pressure loss sensor 30, 31 ... Flow rate sensor 32 ... Controller (deviation estimation means, control means) 33 ... Low speed warning lamp (performance deterioration notification means)

Claims (18)

[Claims] 1. A fuel cell power plant that supplies air and hydrogen to a fuel cell to generate electric power, and an oxygen flow rate detecting means for detecting a value related to an oxygen flow rate in the fuel cell; Oxygen partial pressure detection means for detecting a value related to the oxygen partial pressure, and oxygen of the air supplied to the fuel cell based on the detection signal of at least one of the oxygen flow rate detection means and the oxygen partial pressure detection means. Deviation estimating means for estimating a deviation of the flow rate or oxygen partial pressure from the standard value, and based on the deviation of the oxygen flow rate or oxygen partial pressure estimated by the deviation estimating means, a standard flow rate of air supplied to the fuel cell A fuel cell power plant, comprising: a control unit that controls in a direction closer to the flow rate. 2. The fuel cell power plant according to claim 1, wherein the oxygen flow rate detecting means is a current detecting means for detecting a current or a current density of the fuel cell. 3. A reformer for supplying hydrogen produced by fuel reforming from raw fuel to the fuel cell, and a residual raw fuel concentration detecting means for detecting the concentration of raw fuel remaining in the reformer. 3. The fuel cell power plant according to claim 2, further comprising: the residual raw fuel concentration detection means as the oxygen flow rate detection means. 4. An oxygen flow rate detecting means, comprising: a reformer for supplying hydrogen generated by fuel reforming from raw fuel to the fuel cell; and temperature detecting means for detecting a temperature in the reformer. The fuel cell power plant according to claim 2, wherein the temperature detecting means is also used as the above. 5. The fuel cell power plant according to claim 1, wherein the oxygen partial pressure detecting means is voltage detecting means for detecting the voltage of the fuel cell. 6. A standard of oxygen partial pressure based on a detection value of the oxygen flow rate detection means, wherein a deviation from an oxygen flow rate based on a detection value of the oxygen flow rate detection means is equal to or larger than a first predetermined value. The deviation estimating unit estimates the deviation by applying a flow rate-corrected map in a low flow rate range when the deviation from the value is equal to or less than a second predetermined value. 5. The fuel cell power plant according to any one of 5 above. 7. A standard of oxygen partial pressure based on a detection value of the oxygen partial pressure detection means, wherein a deviation of the oxygen flow rate based on a detection value of the oxygen flow rate detection means from a standard value is equal to or more than a first predetermined value. The deviation estimating means estimates the deviation by applying a flow rate corrected map in the entire flow rate range when the deviation from the value is equal to or larger than a second predetermined value. 5. The fuel cell power plant according to any one of 5 above. 8. The control means controls at least one of a rotation speed changing means of a compressor or a blower which is an air supply source to a fuel cell power plant and a valve opening changing means of a pressure control valve on the fuel cell outlet side. The fuel cell power plant according to any one of claims 1 to 7, characterized in that: 9. The control means sets an upper limit value for the controlled variable depending on conditions.
The fuel cell power plant according to any one of 1. 10. When the rotation speed command value of the compressor or the blower changed by the control means exceeds the rated rotation speed of the electric motor driving the compressor or the blower, the rated rotation speed of the electric motor is set as the upper limit value of the control amount. The fuel cell power plant according to claim 9, which is selected. 11. When the valve opening command value of the pressure control valve changed by the control means exceeds a valve opening maximum value or falls below a valve opening minimum value, the valve maximum opening or valve minimum opening is set as a control amount. 10. The fuel cell power plant according to claim 9, wherein the degree is selected. 12. A performance deterioration notifying means for notifying the driver of performance deterioration when the performance deterioration of the fuel cell power plant due to the control means having set an upper limit value of the control amount is detected by the driver. The fuel cell power plant according to any one of claims 9 to 11, characterized in that. 13. The fuel cell power plant according to claim 1, wherein the estimation by the deviation estimating means is performed during idle operation. 14. The flow rate correction control is not performed when the cognitive information is recognized that the change in the voltage or current of the fuel cell is not caused by the change in oxygen flow rate or oxygen partial pressure. Any one of claims 1 to 13
A fuel cell power plant according to the item. 15. The fuel cell power plant according to claim 14, wherein the recognition information is hydrogen leak detection. 16. The fuel cell power plant according to claim 14, wherein the recognition information is water clogging in the fuel cell. 17. The fuel cell power plant according to claim 14, wherein the recognition information is abnormality detection of an air control valve. 18. The fuel cell power plant according to claim 1, wherein the air supply device for supplying air to the fuel cell is a Rishorum compressor.