JP2004259670A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a failure of a pressure detection system with a minimum configuration without duplication of means for detecting or estimating pressure of each fluid supplied to a fuel cell stack. <P>SOLUTION: An air pressure estimation part of a control computer 2 estimates a pressure Pa of the air supplied to the fuel cell stack 1, based on the power consumption of a motor 4 of a compressor 3, and the rotation rate of the compressor. A pressure sensor 10 detects a pressure Pb of hydrogen supplied to the fuel cell stack 1. A differential pressure sensor 12 detects a pressure difference DPab between the air pressure Pa and the hydrogen pressure Pb. The control computer 2 calculates a difference α between Pb and a sum of Pa and DPab. If α is within a predetermined range, the pressure detection system is determined to be normal, and if α is not within the predetermined range, one of the air pressure estimation part, the pressure sensor 10 or the differential pressure sensor 12 is determined to be failed. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system, and more particularly to a fuel cell system with improved failure detection of a pressure detecting means for a fluid supplied to a fuel cell stack such as a fuel gas, an oxidizing gas, a cooling medium, and pure water for humidification. .
[0002]
[Prior art]
In a fuel cell, a fuel gas such as a hydrogen gas and an oxidizing gas containing oxygen are electrochemically reacted via an electrolyte, and electric energy is directly extracted from between electrodes provided on both surfaces of the electrolyte. In particular, a polymer electrolyte fuel cell using a polymer electrolyte has drawn attention as a power source for electric vehicles because of its low operating temperature and easy handling. That is, a fuel cell vehicle is equipped with a hydrogen storage device such as a high-pressure hydrogen tank, a liquid hydrogen tank, a hydrogen storage alloy tank, etc., and sends hydrogen supplied therefrom and air containing oxygen to the fuel cell to react. Then, the electric energy taken out of the fuel cell drives the motor connected to the driving wheels, and is the ultimate clean vehicle that emits only water.
[0003]
In fuel cell applications where the load fluctuates, such as for vehicles, if the pressure flow rate of the fuel gas and the oxidizing gas supplied to the fuel cell is optimally controlled according to the operating conditions, pumps and compressors that supply the oxidizing gas, etc. The power consumption can be reduced, and the fuel efficiency of the fuel cell can be improved.
[0004]
Therefore, generally, a pressure sensor for detecting the pressure of the fuel gas or the oxidizing gas is provided in the gas supply system, and control is performed such that the detection values of these sensors become the target values. As a conventional technique relating to such a failure diagnosis of pressure sensors, for example, a technique described in Patent Document 1 is known.
[0005]
According to Patent Literature 1, it is disclosed that a pressure sensor and a plurality of valves are used to detect a valve airtightness or the like of a supply fluid of a fuel cell system. Create a room that fluctuates to the desired pressure by using a plurality of valves, perform an initial diagnosis by detecting this pressure fluctuation with a pressure sensor, and then perform a diagnosis such as the presence or absence of a leak state of each valve I have. In this method, failure diagnosis of the pressure sensor during normal operation cannot be performed, and it is necessary to increase the number of valves for diagnosis in order to generate pressure fluctuation.
[0006]
By the way, pressure control of the fluid supplied to the fuel cell system requires high-precision pressure control in order to avoid failure of the fuel cell stack. The conventional method has a redundant configuration in which multiple pressure sensors are installed at one pressure measurement point in order to detect a failure of the pressure sensor during normal operation, and the difference between the pressure values detected by each pressure sensor is within a specified range. If it deviates, the pressure sensor is determined to be faulty.
[0007]
However, in this method, it is necessary to separately install a pressure sensor for failure detection in addition to the pressure sensor used in the control, and the number of wirings and the size of the control computer are increased for these failure detection pressure sensors. As a result, the cost of the fuel cell system has been raised.
[0008]
In the conventional methods including Patent Literature 1, a large number of parts other than those for normal pressure control must be provided for failure detection or diagnosis, and there is a concern that the increase in the number of parts may increase failure factors. There was also.
[0009]
[Patent Document 1]
JP-A-9-22711 (page 4, FIG. 1)
[0010]
[Problems to be solved by the invention]
In the above-mentioned conventional technology, many parts such as a valve for diagnosis and a pressure sensor for failure detection or diagnosis are required in addition to a valve for pressure value control and a pressure sensor for control.
[0011]
This means that a diagnostic system must be prepared separately from the one for controlling the pressure and flow rate of the fluid.The number of parts and components increases, and therefore the failure rate increases due to an increase in failure factors. There was a problem of doing.
[0012]
In addition, there is a problem in that the cost of the entire fuel cell system is increased because a dedicated system for diagnosis such as a diagnostic pressure sensor must be provided.
[0013]
[Means for Solving the Problems]
The present invention provides a fuel cell system having a path for supplying at least two types of fluids from a fuel gas, an oxidizing gas, a cooling medium, and pure water for humidification to a fuel cell stack in order to solve the above problems. First pressure detecting means for detecting or estimating and estimating the pressure value of a first fluid of a plurality of types of fluids, and detecting or estimating a pressure value of a second fluid of the plurality of types of fluids A second pressure detecting means for outputting the pressure, and a pressure difference detecting means for detecting a pressure difference which is a pressure of the second fluid with respect to a pressure of the first fluid, wherein the output value of the first pressure detecting means is Failure detection of the first pressure detection means, the second pressure detection means, and the pressure difference detection means is performed based on a comparison result between a value obtained by adding the detection value of the pressure difference detection means and an output value of the second pressure detection means. The point is to perform
[0014]
【The invention's effect】
According to the present invention, the value obtained by adding the detection value of the pressure difference detection means to the output value of the first pressure detection means is compared with the output value of the second pressure detection means, and the difference between the two exceeds a predetermined range. In this case, it can be determined that one of the first pressure detecting means, the second pressure detecting means, and the pressure difference detecting means has failed, so that the failure of the pressure detecting means can be detected without duplicating each pressure detecting means. effective.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
Next, a first embodiment of a fuel cell system according to the present invention will be described in detail with reference to FIGS.
[0016]
FIG. 1 is a system configuration diagram illustrating a fuel cell system according to a first embodiment, FIG. 2 is a correlation diagram of pressure in the first embodiment, and FIG. 3 is a system configuration diagram of a conventional fuel cell system as a comparative example. 4, FIG. 4 is a pressure correlation diagram in the conventional example, FIG. 5 is a characteristic diagram of the supercharging pressure and the consumption current of the supply route a in the present embodiment, and FIG. 6 is a supply route a used for estimating the atmospheric pressure. And FIG. 7 is a flowchart showing a normal diagnosis procedure in the present embodiment.
[0017]
In the system configuration diagram of FIG. 1, the fuel cell system includes a fuel cell stack 1 for generating electric power, a control computer 2 for controlling the entire system including failure detection and diagnosis of a pressure sensor and pressure estimating means, and a fluid a. A compressor 3 that is a fluid machine that pressurizes air and supplies the fuel to the fuel cell stack 1, a motor 4 that drives the compressor 3, a supply path 5 that guides the fluid a to the compressor 3, and a path 6 that discharges the fluid a. A supply path 7, a discharge path 8, a power extraction circuit 9 from the fuel cell stack 1, a pressure sensor 10 as a pressure detecting means of the fluid b, and a pressure estimation value 11 of the fluid a, The pressure difference between the fluid a and the fluid b (differential pressure value), the control harness 13, and the pressure of the fluid a supplied to the fuel cell stack 1 are adjusted. That the pressure control valve 14, and is configured with a.
[0018]
Although not shown, for example, a high-pressure hydrogen tank and a pressure control valve are connected to the hydrogen supply path 7, and the control computer 2 controls the pressure control valve to supply hydrogen gas of a desired pressure to the supply path 7. Can be supplied.
[0019]
In the first embodiment, the fluid a (air) is illustrated as the first fluid and the fluid b (hydrogen) is illustrated as the second fluid from the fluids supplied to the fuel cell stack 1.
[0020]
The fuel cell system 1 controls the control computer 2 as first pressure detecting means for estimating the pressure of the fluid a (air) as the first fluid, and detects the pressure of the fluid b (hydrogen) as the second fluid. A pressure sensor 10 is provided as second pressure detecting means for detecting a pressure difference of the second fluid with respect to a pressure of the first fluid, and a differential pressure sensor 12 is provided as a pressure difference detecting means for detecting a pressure difference between the first fluid and the output of the first pressure detecting means. The fault value is detected by comparing the value obtained by adding the detection value of the pressure difference detection means to the value and the output value of the second pressure detection means.
[0021]
In the following description, the control computer 2 as the first pressure detecting means, the pressure sensor 10 as the second pressure detecting means, and the differential pressure sensor 12 as the pressure difference detecting means are also called a pressure detecting system.
[0022]
Next, FIG. 2 which is a correlation diagram, FIG. 5 which shows a supercharging characteristic of a compressor, FIG. 6 which shows a characteristic for estimating the atmospheric pressure, and FIG. Will be described with reference to FIG. As a comparative example, a method of detecting a failure of a pressure sensor in a conventional fuel cell system will be described with reference to FIGS. 3 and 4, and a difference from the first embodiment will be compared.
[0023]
In the case of the first embodiment, hydrogen that is the supply fluid b is usually stored in a compressed state in many cases, and there is no need for pressurization by a fluid machine such as a compressor. Most of the time. For this reason, in this supply path, it is difficult to estimate the pressure value based on the load of the fluid machine and the like, and the pressure value (Pb [kPa]) from the vacuum is directly detected by the pressure sensor 10. .
[0024]
In the present embodiment, a fluid machine such as a compressor or a pump is operated by a motor to supply air or cooling fluid. Therefore, the compressor or the like is detected by detecting a power consumption value of the motor or a current value under a constant voltage. The amount of energy consumption of the motor can be detected, and the rotation speed of the motor can be known by detecting the data of the rotation command value of the inverter used for controlling the flow rate of the supply fluid such as the compressor.
[0025]
If the rotation speed of the motor is known, the rotation speed of the compressor or the like can be known from the specifications of the transmission device between the motor and the compressor or the like, so that the discharge amount of fluid from the compressor or the like can be known. When the discharge amount and the energy conversion amount of the fluid supplied to the fuel cell are known, the fuel cell stack is indirectly calculated by experiments such as a relational expression of pressure and current consumption at an arbitrary rotation speed, a gas state equation, and the like. Can be estimated.
[0026]
The path of the air as the supply fluid a is premised on supercharging using a compressor and a motor. An estimated pressure value (Pa ′ [kPa]) output from the compressor is obtained from the electric energy consumed for driving the compressor, the rotation speed of the compressor, and the energy conversion efficiency of the compressor. FIG. 5 shows a relationship between the supercharging pressure and the consumed current value when the supply voltage of the compressor driving motor is constant. The pressure value supercharged by the consumed current value can be estimated from the relational expression of this characteristic.
[0027]
Actually, the current consumption and the supercharging pressure are different depending on the rotation speed of the motor. Therefore, a map for obtaining the supercharging pressure based on the rotation speed and the current consumption as shown in FIG. Search and find the boost pressure. Thus, the pressure of the air supplied to the fuel cell stack can be estimated without providing a pressure sensor in the air supply path.
[0028]
However, even if the supercharging pressure is the same, the supercharging pressure output from the compressor differs depending on the atmospheric pressure before supercharging. Therefore, in a fuel cell system that can be moved to high altitudes, such as for a vehicle, the atmospheric pressure is known. There is a need.
[0029]
By the way, if the situation at the time of pressure reduction, that is, the pressure loss is known, the situation at the time of supercharging can be known, and the pressure value can be estimated by this method.
[0030]
Therefore, the pressure loss of the fuel cell stack 1, which is a factor of the pressure loss of the air as the fluid a, is made constant by fully opening the pressure regulating valve 14, and the power generation state of the fuel cell stack 1 is made constant by idling or the like. In this state, the pressure loss of the entire air supply path can be kept constant.
[0031]
In a series of operating states from the start to the stop of the fuel cell, there is little need for power generation immediately after the start, immediately before the stop, immediately before the idling stop, and the like, and the valve opening state of the supply path can be set arbitrarily. For this reason, it becomes possible to control the valve opening to keep the pressure loss constant, and to accurately estimate the atmospheric pressure.
[0032]
That is, by operating the compressor 3 at a constant rotation with the pressure loss kept constant, the current consumption of the compressor according to the atmospheric pressure is detected, and the atmospheric pressure can be estimated from the relationship between the current consumption and the atmospheric pressure. . The relative pressure Pa ′ is converted into the absolute pressure Pa by multiplying Pa ′ by a predetermined coefficient obtained from the estimation of the atmospheric pressure.
[0033]
Thus, even if the relative pressure to the atmospheric pressure and the absolute pressure are mixed in the estimated pressure value or the detected pressure value, failure detection and diagnosis by comparing the pressure values can be performed by aligning the reference pressures of Pa and Pb. Will be possible.
[0034]
The pressure control of the fluid supplied to the fuel cell stack in the normal control uses the Pa and Pb to realize the pressure control in the supply path of each fluid.
[0035]
In the first embodiment, each pressure value is considered based on the absolute pressure from vacuum. The relation between the detected pressure value or estimated pressure value of the fluid a, the detected pressure value or estimated pressure value of the fluid b, and the differential pressure value from the differential pressure sensor that measures the pressure difference between the fluid a and the fluid b is shown. And the following equation (1), and equation (2) is derived from equation (1).
[0036]
(Equation 1)
Pa + DPab = Pb + α (1)
α = Pa + DPab−Pb (2)
Here, Pa [kPa]: the detected pressure value or estimated pressure value Pb [kPa] of the fluid a: the detected pressure value or estimated pressure value DPab [kPa] of the fluid b: the pressure of the fluid b relative to the pressure of the fluid a (differential pressure) value)
α [kPa]: FIG. 2 shows the relationship of error (1), and shows that the sum of Pa and DPab corresponds to Pb.
[0037]
If the error α in the equations (1) and (2) is within the predetermined range, it is possible to determine that normal operation is possible without any failure in the pressure detection system because the entire system is matched. On the other hand, when the error α is out of the predetermined range, there is an error in the pressure value of Pa, Pb, or DPab, and the pressure detecting means or the differential pressure sensor that detects or estimates the pressure value fails. You can judge that you are doing.
[0038]
The predetermined range for determining whether the error α is normal or abnormal is based on the characteristic of each pressure sensor or the input error of the pressure estimation method and the characteristic of the estimation method, and the allowable error of the pressure value Pa [kPa] of the fluid a. (Tolerance), the allowable error of the pressure value Pb [kPa] of the fluid b, and the allowable error of the differential pressure value DPab [kPa].
[0039]
By the way, when a failure of a pressure sensor is detected in a system configuration in which a conventional pressure sensor is duplicated, a diagnostic pressure sensor is provided at the same place as the control pressure sensor as shown in FIG. Then, the fault diagnosis is performed by directly comparing the detection value of the fluid b pressure sensor 10 and the detection value of the same pressure sensor 11 and the detection value of the fluid a pressure sensor 12 and the detection value of the same pressure sensor 13. This state is shown in the correlation diagram of FIG.
[0040]
In the conventional method, a pressure sensor dedicated to diagnosis is added in addition to the pressure sensor for control, and the number of components dedicated to diagnosis is increased, so that the number of failure factors is increased, thereby making the entire system complicated and expensive. .
[0041]
Next, a diagnosis operation for detecting a failure during normal operation in the present embodiment will be described with reference to a flowchart of FIG.
[0042]
First, when diagnosis during normal operation is started, in step S12, the pressure Pa ′ (relative pressure) of the fluid a (air) is estimated from the power consumed by the compressor, the rotation speed of the compressor, and the energy conversion efficiency of the compressor. I do. Next, in step S14, the atmospheric pressure is estimated, and the pressure Pa ′ (relative pressure) is corrected based on the estimated atmospheric pressure to obtain the pressure Pa (absolute pressure). To estimate the atmospheric pressure, the compressor is rotated at a constant rotational speed by keeping the pressure loss of the entire air supply path constant by keeping the power generation state of the fuel cell stack constant, such as when the vehicle is idling. The atmospheric pressure is estimated from the power consumption of the compressor at that time. If the state of the vehicle is not idling, the previous estimated atmospheric pressure value stored in advance is used.
[0043]
Next, in step S16, Pb (absolute pressure) is detected by the pressure sensor of the fluid b (hydrogen), and in step S18, the fluid a. The differential pressure value DPab is detected by the differential pressure sensor between b and b.
[0044]
Next, in step S20, based on Pa, Pb, and DPab, error α is calculated by equation (2), and it is determined in step S22 whether error α is within a predetermined range. If it is determined in step S22 that the error α is within the predetermined range (within the allowable range), the process proceeds to step S24, and the pressure detection system is determined to be normal, and the process ends. If it is determined in step S22 that the error α is out of the predetermined range, the process proceeds to step S26, and the pressure detection system ends as a failure state.
[0045]
According to the present embodiment described above, the failure of the pressure detecting means for detecting or estimating the pressure of each fluid is detected without duplicating the detection of the pressures of the first and second fluids supplied to the fuel cell stack. There is an effect that can be.
[0046]
[Second embodiment]
The configuration of the second embodiment is the same as that of the first embodiment shown in FIG. In the second embodiment, in particular, the diagnosis is performed by diagnosing the pressure value of each fluid supply path and specifying which of the pressure detecting means and the pressure difference detecting means for detecting or estimating the pressure value of each fluid is faulty. Having a function is a feature of the second embodiment.
[0047]
In the present embodiment, by detecting an abnormal pressure value for each supply path of each fluid at a timing when there is no power generation request immediately after the start of the fuel cell, it is possible to specify a failure point of the pressure detection system of the fuel cell system. .
[0048]
At this time, the diagnosis of the hydrogen in the supply path b is performed at the end, and the operation can be shifted to the normal operation control or the normal failure diagnosis without reducing the pressure by releasing the pressure to the atmosphere. As a result, the fuel cell can be diagnosed at the time of starting without wasting the fuel hydrogen, and the fuel efficiency of the fuel cell can be improved.
[0049]
In the case of the second embodiment, immediately after the start, the hydrogen path is initially kept at a low pressure and kept in a constant state, and only the air path is first closed by closing the pressure regulating valve 14 to a predetermined opening to release the air. By pressurizing, the amount of change in the air pressure value is compared with the amount of change in the differential pressure value between hydrogen and air. First, at this stage, a failure diagnosis of the air supply path is performed to determine the quality.
[0050]
Thereafter, only the determination result is recorded irrespective of the result of the determination, and the pressure of the air is held while the operating state of the air supply path such as the fuel cell stack and the compressor is kept constant. Next, pressurize the hydrogen supply circuit, compare the change in the hydrogen pressure value with the change in the differential pressure value between hydrogen and air, and perform a fault diagnosis on the hydrogen path as well as the air path. The pass / fail judgment is made.
[0051]
If there is no problem in both of the diagnoses in the pass / fail determination, there is no failure, and the operation proceeds to the normal operation and the normal pressure diagnosis. When it is determined that only the air path is in a failure state, it is a failure state of the means for estimating the pressure of the air path, and when it is determined that the failure is only in the hydrogen path, the pressure detection means of the hydrogen path is used. It is in a failure state.
[0052]
If there is a problem in both of the diagnoses, it is determined that the pressure difference detecting means for detecting the differential pressure value or the control computer is abnormal. Since the degree of importance given to the system depends on the failure state, fail-safe control after the determination can be diversified according to each failure state.
[0053]
FIG. 8 is an operation flowchart of an initial diagnosis for specifying a failure location of the pressure detection system in the second embodiment.
[0054]
First, when the initial diagnosis is started, in step S32, the compressor 3 pressurizes the supply path of the air as the fluid a. Next, in step S34, the pressure Pa ′ (relative pressure) of the fluid a (air) is estimated from the power consumed by the compressor, the rotational speed of the compressor, and the energy conversion efficiency of the compressor, and the atmosphere detected by the pressure sensor of the fluid b is detected. The pressure Pa ′ (relative pressure) is corrected by the pressure value to obtain the pressure Pa (absolute pressure). Here, since the supply of the hydrogen as the fluid b has not been started yet, the pressure of the hydrogen supply passage is at the atmospheric pressure.
[0055]
Next, in step S36, the fluid a. The differential pressure value DPab is detected by the differential pressure sensor between b and b. Next, in step S38, based on Pa, Pb, and DPab, the error α is calculated by equation (2), and in step S40, it is determined whether the error α is within a predetermined range.
[0056]
If the determination in step S40 is No, that is, if the error α is out of the predetermined range, the process proceeds to step S42, in which the pressure detecting means for estimating the pressure of the air supply path for supplying the fluid a is stored in a failure state, Move to step S44.
[0057]
If the determination in step S40 is Yes, that is, if the error α is within a predetermined range (within tolerance), the process proceeds to step S44, and the pressure in the air supply path is maintained.
[0058]
Next, in step S46, the hydrogen pressure regulating valve is opened to pressurize the hydrogen gas in the fluid b supply path 7, and the pressure value of the fluid b (hydrogen) pressure sensor 10 is read in step S48. In step S50, the fluid a. The differential pressure value DPab is detected by the differential pressure sensor between b and b. In step S52, based on Pa, Pb, and DPab, error α is calculated by equation (2), and in step S54, it is determined whether error α is within a predetermined range.
[0059]
If it is determined in step S54 that the error α is within the predetermined range (within the allowable range), the process proceeds to step S56, and the pressure detection system of the supply path of the fluid b is determined to be normal, and the processing ends. If it is determined in step S54 that the error α is out of the predetermined range, the process proceeds to step S58, and the pressure detection system in the supply path of the fluid b ends as a failure.
[0060]
In the present embodiment, the failure can be determined by comparing the change in the pressure value while reducing the supply path one by one, as in the case of the start-up at the time of the stop. If there is one mismatched pressure value, there is an error in the supply path pressure value of the fluid. If there are two mismatched supply path pressure values, these fluid supply paths In this state, there is an error in the differential pressure value. By performing the above-described diagnostic method for each fluid supply path, a failure location can be identified by analyzing a combination that does not maintain a correlation between pressure values and is inconsistent.
[0061]
According to the present embodiment described above, the pressure of each fluid supply path is detected or estimated by sequentially pressurizing the supply path of each fluid when power generation is not performed immediately after the start or stop of the fuel cell system. It is possible to diagnose which of the pressure detection means for detecting the pressure difference and the pressure difference detection means for detecting the pressure difference between the fluid supply paths is faulty, and to specify the faulty part.
[0062]
[Third embodiment]
FIG. 9 is a system configuration diagram illustrating a third embodiment of the fuel cell system according to the present invention, and FIG. 10 is a pressure correlation diagram in the third embodiment.
[0063]
FIG. 9 shows a configuration of a method for diagnosing a pressure detection system for a fluid a (air), a fluid b (hydrogen), and a fluid c (cooling water) to be supplied to the fuel cell stack 1. A method of diagnosing the pressure sensor in the system will be described with reference to FIG.
[0064]
In the case of the third embodiment, the pressure of the air that is the supply fluid a is estimated from the electric power consumed by the compressor, as in the first embodiment. Also in the cooling water which is the supply fluid c, the only difference is that a pump is used in the supply fluid c instead of the compressor of the supply fluid a, and the same applies except that the coefficients of the characteristics as shown in FIGS. 5 and 6 are different. The supply pressure value can be estimated, and Pa and Pc can be obtained.
[0065]
Further, by obtaining the pressure difference DPab between the fluids a and b and the pressure difference DPbc between the fluids b and c, a failure can be detected by evaluating the error β in the following equation (3).
[0066]
(Equation 2)
Pa + DPab + DPbc = Pc + β (3)
Here, Pa [kPa]: detected pressure value or estimated pressure value Pc [kPa] of fluid a: detected pressure value or estimated pressure value DPab [kPa] of fluid c: detected pressure difference value between fluids a and b (differential pressure) value)
DPbc [kPa]: Detected pressure difference between fluids b and c (differential pressure value)
β [kPa]: If there is no problem in the pressure values (detected value and estimated value) of all errors, the error β is within a predetermined range. If any of the pressure values is incorrect, the error β falls outside the predetermined range, and it can be determined that the pressure sensor or the pressure estimating means at any one place is in a failure state. The predetermined range for determining whether the error β is normal or abnormal is the pressure value Pa [of the fluid a based on the characteristics of each pressure sensor or the input error of the pressure estimation method and the characteristics of the estimation method, as in the first embodiment. kPa], the tolerance of the pressure value Pc [kPa] of the fluid c, the tolerance of the differential pressure value DPab [kPa], and the tolerance of the differential pressure value DPac [kPa]. It is assumed that it is calculated and determined.
[0067]
The third embodiment is characterized in that the following equations (4) and (5) are used to obtain the pressure Pb [kPa] of the fluid b. In normal control, the pressure control is performed based on the value of Pb. Has been done.
[0068]
[Equation 3]
Pb = Pa + DPab (4)
Pb = Pc-DPbc (5)
The method of failure detection is the same as that of the first embodiment. If β in the above equation (3) deviates from a predetermined range, it is determined that a failure has occurred. Also, as in the second embodiment, when the power generation is not performed immediately after the start of the fuel cell system, the supply path of each fluid is sequentially pressurized, and the supply path of each fluid is also determined. It is possible to specify a failure point as to which of the pressure detection means for detecting or estimating the pressure of the fluid supply pressure and the pressure difference detection means for detecting the pressure difference between the fluid supply paths has failed.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram illustrating a first embodiment of a fuel cell system according to the present invention.
FIG. 2 is a pressure correlation diagram in the first embodiment.
FIG. 3 is a system configuration diagram of a conventional fuel cell system.
FIG. 4 is a pressure correlation diagram in a conventional configuration.
FIG. 5 is a characteristic diagram of supercharging pressure and current consumption of a supply path a.
FIG. 6 is a characteristic diagram of current consumption and atmospheric pressure at a constant rotation speed of a compressor in a supply path a used for estimating atmospheric pressure.
FIG. 7 is a flowchart illustrating an inspection procedure during normal operation according to the first embodiment.
FIG. 8 is a flowchart illustrating a procedure of an initial diagnosis for specifying a fault location according to the second embodiment.
FIG. 9 is a system configuration diagram illustrating a third embodiment of the fuel cell system according to the present invention.
FIG. 10 is a pressure correlation diagram in the third embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 2 ... Control computer 3 ... Compressor 4 ... Motor 5 ... Fluid a (air) supply path 6 ... Fluid a discharge path 7 ... Fluid b (hydrogen) supply path 8 ... Fluid b discharge path 9 ... Electric power output Circuit 10 Fluid b pressure sensor 11 Fluid a estimated pressure 12 Fluid a-b differential pressure sensor 13 Control harness 14 Fluid a pressure regulating valve

Claims (7)

A fuel cell system having a path for supplying at least two kinds of fluids from a fuel gas, an oxidizing gas, a cooling medium, and pure water for humidification to a fuel cell stack,
First pressure detection means for detecting or estimating and outputting a pressure value of a first fluid of the plurality of types of fluids,
Second pressure detecting means for detecting or estimating and outputting a pressure value of a second fluid of the plurality of types of fluids,
Pressure difference detection means for detecting a pressure difference that is a pressure of the second fluid with respect to a pressure of the first fluid,
Based on a comparison result of a value obtained by adding a detection value of the pressure difference detection means to an output value of the first pressure detection means and an output value of the second pressure detection means, the first pressure detection means and the second pressure A fuel cell system for detecting a failure in a detecting means and the pressure difference detecting means. Third pressure detecting means for detecting or estimating and outputting a pressure value of a third fluid among the plurality of types of fluids,
A second pressure difference detecting means for detecting a pressure difference that is a pressure of the third fluid with respect to a pressure of the first fluid,
Based on a comparison result of a value obtained by adding a detection value of the second pressure difference detection means to an output value of the first pressure detection means and an output value of the third pressure detection means, the first pressure detection means and the third pressure detection means 3. The fuel cell system according to claim 1, wherein failure detection is performed on the three pressure detecting means and the second pressure difference detecting means. The first or second pressure detecting means includes:
Based on power consumption or current consumption of a motor that drives a fluid machine that supplies the first or second fluid to the fuel cell stack, a rotation speed of the fluid machine, and an energy conversion efficiency characteristic of a fluid machine system. The fuel cell system according to claim 1, wherein the pressure value is estimated. With the pressure loss of the fuel cell stack kept constant, a fluid machine that supplies fluid to the fuel cell stack is operated, and a large amount is determined based on the power consumption or current consumption of a motor that drives the fluid machine and the rotation speed of the fluid machine. With atmospheric pressure estimation means for estimating atmospheric pressure,
As the first or second pressure detecting means, a relative pressure detecting means for detecting or estimating and outputting a pressure with respect to an atmospheric pressure and an absolute pressure detecting means for detecting or estimating and outputting an absolute pressure are mixedly provided.
4. The fuel cell system according to claim 1, wherein a conversion between a relative pressure value and an absolute pressure value is performed using an estimated value of the atmospheric pressure estimating means. The atmospheric pressure estimating means includes:
Immediately after the start or stop of the fuel cell stack, power generation is not performed, and various valves for controlling the supply path of the fluid are fixed in a predetermined state, and the pressure loss in the path of the fluid is kept constant to reduce the atmospheric pressure. The fuel cell system according to claim 4, wherein the estimation is performed. Each of the plurality of types of fluids is sequentially pressurized immediately after startup, and sequentially depressurized immediately before stoppage, while changing the detection value of the first pressure detection unit and the pressure difference detection unit. Which of the first pressure detecting means or the second pressure detecting means or the pressure difference detecting means is based on a comparison result between the change in the detected value and the change in the detected value of the second pressure detecting means. The fuel cell system according to claim 5, wherein it is diagnosed whether or not the fuel cell is out of order. If the path for supplying the fuel gas to the fuel cell stack is pressurized immediately after startup, the pressure is not reduced after the pressurization, and the diagnosis is continued by maintaining the pressurized state as the reference pressure in the failure diagnosis, or 7. The fuel cell system according to claim 6, wherein a diagnosis is performed by finally pressurizing the fuel cell, and the fuel gas is not released from the supply path for pressure reduction.

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