JP2009181793A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly estimate the amount of oxygen remaining in an anode during the startup control. <P>SOLUTION: At the time of startup of a fuel cell system, supply of air to a fuel cell stack 1 and discharge of hydrogen gas are stopped to supply the hydrogen gas to the fuel cell stack 1. In the startup control for taking the current out of the fuel cell stack 1, the amount of oxygen remaining in an anode is estimated on the basis of the behavior of hydrogen gas pressure detected by a pressure sensor 9, and the end time for finishing the startup control is set up on the basis of the estimated amount of oxygen. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system that performs startup control when starting a fuel cell system.

  Conventionally, as this type of technology, for example, those described in the following documents are known (see Patent Document 1). When starting the fuel cell system in a state where oxygen is mixed in the anode of the fuel cell, the fuel gas set to a pressure higher than that in the normal power generation state is supplied to the anode, and the oxygen remaining in the anode is removed. Immediate replacement with fuel gas. By performing such start-up control, the uneven distribution of the fuel gas and the oxidant gas in the anode is suppressed, the formation of local cells due to the uneven distribution of the reaction gas is suppressed, and the deterioration of the electrodes is prevented.

Whether or not to perform such start-up control is determined according to the amount of oxygen remaining in the anode, and this amount of oxygen is determined by the amount of time left between the last stop of the fuel cell system and the current start-up. Depends on. Therefore, a timer is provided in the fuel cell system, the standing time is calculated by this timer, the amount of oxygen staying in the anode is estimated based on the calculated time, and it is determined whether or not to perform the start-up control. .
JP2004-139984

  In the above conventional fuel cell system, the amount of oxygen staying in the anode is estimated based on the standing time calculated by the timer provided in the system. It has been difficult to accurately and appropriately estimate the amount of oxygen remaining in the water.

  Accordingly, the present invention has been made in view of the above, and an object thereof is to provide a fuel cell system capable of appropriately estimating the amount of oxygen remaining in the anode at the time of startup. .

  In order to achieve the above object, means for solving the problems of the present invention include a fuel gas supplied to the fuel electrode by the fuel gas supply means, and an oxidant gas supplied to the oxidant electrode by the oxidant gas supply means. In a fuel cell system including a fuel cell that generates electric power by an electrochemical reaction, pressure detecting means for detecting a pressure of fuel gas at the fuel electrode, and unused fuel gas supplied to the fuel cell Discharge means for discharging to the outside, current extraction means for taking out the current obtained from the fuel cell from the fuel cell, supply of fuel gas by the fuel gas supply means, and supply of oxidant gas by the oxidant gas supply means Control means for controlling supply, discharge of fuel gas by the discharge means, and extraction of current by the current extraction means. Sometimes, in a state where the supply of the oxidant by the oxidant supply means and the discharge of the fuel gas by the discharge means are stopped, the fuel gas is supplied by the fuel gas supply means, and the start-up control for taking out the current by the current extraction means is performed. When performing, the amount of oxygen staying in the fuel electrode is estimated based on the behavior of the fuel gas pressure detected by the pressure detecting means.

  According to the present invention, it is possible to appropriately estimate the amount of oxygen remaining in the anode before the fuel cell system is started.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a fuel cell system according to Embodiment 1 of the present invention. The system of Embodiment 1 shown in FIG. 1 includes a fuel cell stack 1 and a hydrogen system (anode system) configured to supply and discharge hydrogen gas as a fuel gas to the fuel cell stack 1. A main valve 3, a pressure reducing valve 4, a hydrogen supply valve 5, a hydrogen circulation pump 6, a purge valve 7, a dilution device 8, a pressure sensor 9, and a temperature sensor 10 are provided. Further, a compressor 11, an air pressure regulating valve 12, a pressure sensor 13, and a temperature sensor 14 are provided as an air system (cathode system) configuration for supplying and discharging oxidant gas air to and from the fuel cell stack 1. The system further includes a voltage sensor 15, a power manager 16, a secondary battery 17, a battery controller 18, an atmospheric pressure sensor 19, and a controller 20.

  In the fuel cell stack 1, hydrogen gas is supplied as fuel gas to the anode, and air (oxygen) is supplied as oxidant gas to the cathode, and the electrode reaction shown below proceeds to generate electric power.

Anode electrode reaction: H ₂ → 2H ⁺ + 2e ⁻
Cathode reaction: 2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O
Hydrogen is supplied to the anode of the fuel cell stack 1 from the hydrogen tank 2 through the hydrogen tank main valve 3, the pressure reducing valve 4, and the hydrogen supply valve 5. The high-pressure hydrogen supplied from the hydrogen tank 2 is mechanically reduced to a predetermined pressure by the pressure reducing valve 4, and the hydrogen pressure at the fuel cell inlet at the hydrogen supply valve 5 satisfies a desired hydrogen supply amount. The pressure is controlled based on the pressure measured by the pressure sensor 9 (pressure detecting means) provided on the fuel cell inlet side so as to be the hydrogen pressure. The pressure sensor 9 detects the pressure of the fuel gas at the anode when the supply of hydrogen is stopped.

  The hydrogen supply valve 5 has its valve opening adjusted, for example, using electromagnetic force generated in the drive coil based on the open / close signal, and the current flowing through the drive coil changes depending on the temperature, or the friction of the mechanical system changes. Therefore, the actual opening degree with respect to the command opening degree corresponding to the open / close signal changes. For this reason, the representative temperature of the hydrogen supply valve 5 is measured by the temperature sensor 10, and the command opening is set corresponding to the actual opening based on the measured temperature.

  In other words, the relationship between the commanded opening and the actual opening with respect to the temperature is obtained in advance through simulations of experiments and desk studies, etc., and the obtained relationship is stored in a storage device or the like as a map, and hydrogen is supplied with reference to this map. The opening degree of the valve 5 is adjusted and controlled. The basic characteristics of temperature and opening tend to reduce the error of the actual opening with respect to the command opening as the temperature rises.

  The hydrogen circulation pump 6 is installed to recycle hydrogen that has not been consumed at the anode. Since air is supplied to the cathode side, nitrogen that is contained in the air and does not chemically react passes through the electrolyte membrane of the fuel cell stack 1 and accumulates in the hydrogen path. If the accumulated amount of nitrogen becomes too large, hydrogen cannot be circulated by the hydrogen circulation pump 6, so it is necessary to manage the amount of nitrogen in the circulation path. Therefore, the nitrogen in the circulation path is discharged to the outside through the purge valve 7, and the amount of nitrogen existing in the hydrogen path is managed to such an extent that the circulation performance can be maintained.

  The diluting device 8 introduces unused air discharged from the fuel cell stack 1 before releasing the hydrogen discharged simultaneously with the purge valve 7 when nitrogen is discharged to the outside of the system. And hydrogen are stirred to dilute and exhausted out of the system. In addition to this, the hydrogen treatment system may include a combustor or a direct discharge method without a dilution device.

  Air pressurized by the compressor 11 is supplied to the cathode of the fuel cell stack 1, and the air pressure regulating valve 12 adjusts the pressure of the air supplied to the cathode, and the air pressure is provided in the vicinity of the fuel cell stack 1. It is adjusted based on the pressure measured by the pressure sensor 13. For example, when it is desired to increase the electric power extracted from the fuel cell stack 1, the reaction efficiency in the fuel cell stack 1 is increased to an energy density that can be extracted by pressurizing the air supplied to the fuel cell stack 1.

  The compressor 11 has such characteristics that volumetric efficiency deteriorates due to temperature rise, and flow rate characteristics with respect to the rotational speed deteriorate. For this reason, the temperature of the air discharged from the compressor 11 is measured by the temperature sensor 14 provided at the cathode inlet of the fuel cell stack 1, and the measured temperature of the air is set as the representative temperature of the compressor 11, and based on this representative temperature. The rotational drive of the compressor 11 is controlled. That is, the relationship between the rotational speed with respect to the temperature and the discharge flow rate is obtained in advance through simulations of experiments and desktop examinations, etc., and the obtained relationship is prepared as a map stored in a storage device or the like. Control the drive.

  Further, the compressor 11 has such characteristics that the air density to be sucked in is reduced due to the drop in the atmospheric pressure, and the flow rate characteristic with respect to the rotational speed is deteriorated. For this reason, the atmospheric pressure is measured by the atmospheric pressure sensor 19, and the rotational drive of the compressor 11 is controlled based on the measured atmospheric pressure. That is, the relationship between the rotational speed with respect to the atmospheric pressure and the discharge flow rate is obtained in advance through simulations of experiments and desk studies, and the obtained relationship is stored as a map in a storage device or the like. Controls rotational drive.

  The voltage sensor 15 is provided in the fuel cell stack 1 and measures a cell voltage for each of a large number of cells constituting the fuel cell stack 1 or a predetermined number of cells.

  The power manager 16 (current extraction means) takes out electric power from the fuel cell stack 1, and drives to a consumer that mainly consumes the extracted electric power, for example, a drive motor (not shown) that drives a moving body such as a fuel cell vehicle. Supply. The power manager 16 has a function (current detection means) for measuring a current taken out from the fuel cell stack 1 for power take-out control.

  The secondary battery 17 supplies power necessary for driving auxiliary machinery necessary for generating power in the fuel cell system, and the generated power of the fuel cell stack 1 with respect to the power required for the fuel cell system. When there is a shortage of power, supply the power for the shortage. Conversely, the secondary battery 17 stores surplus power when the generated power of the fuel cell stack 1 becomes surplus. Further, when the consumer that mainly consumes the electric power obtained by the fuel cell stack 1 is a drive motor, the secondary battery 17 charges the regenerative power of the drive motor.

  The battery controller 18 measures the charge amount of the secondary battery 17 and controls charging / discharging of the secondary battery.

  The controller 20 (control means) functions as a control center that controls the operation of the system, and includes resources such as a CPU, a storage device, and an input / output device necessary for a computer that controls various operation processes based on a program. For example, it is realized by a microcomputer or the like. The controller 20 reads signals from the sensors (not shown) that collect information necessary for operation of the system, such as the above-mentioned sensors and other pressures, temperatures, concentrations, voltages, and currents that cannot be obtained by these sensors. Based on the various signals read and control logic (program) stored in advance, commands are sent to the components that require control of the system, including the actuators of the above-mentioned valves. All operations necessary for operation / stop of this system including the control end judgment operation are managed and controlled. The controller 20 executes start start control and power generation stop control based on a start start command and a power generation stop command given from a start switch (not shown). When this fuel cell system is mounted on a fuel cell vehicle, the start switch serves as an ignition key for the vehicle, and controls the amount of power generated during power generation based on the accelerator opening.

  FIG. 2 is a diagram illustrating a configuration of control logic (program) stored in a storage device or the like included in the controller 20. The control logic includes anode pressure control means 21A for controlling the pressure of the hydrogen gas supplied to the anode. The start control means 21 for controlling the start-up control at the start-up of the fuel cell system, the start control and the start control are completed. After that, it is configured to include a start-up control / normal power generation control switching means 22 for switching between normal power generation and a normal power generation control means 23 for controlling normal power generation.

  Next, the operation of the fuel cell system according to the first embodiment will be described as an example with reference to FIG. FIG. 3 is a flowchart showing the operation at the start-up of the fuel cell system according to the first embodiment.

  In this system, all the components are in a stopped state when the system is stopped, the hydrogen supply valve 5 is closed, the hydrogen circulation pump 6 is stopped, and the purge valve 7 is closed.

  First, when the driver turns on the ignition and starts the system, the supply of power from the secondary battery 17 or lead storage battery installed in a gasoline vehicle (not shown) to the accessories and system auxiliary parts is started. Start preparing for system operation. Whether or not the control logic (program) of the controller 20 is initialized by executing signal processing such as a flag and a timer by exchanging signals between various auxiliary components and the controller 20, and is ready for execution control When the activation execution permission flag is set, the process proceeds to the next step S302 (step S301).

  Subsequently, system activation control is started (step S302). First, the start control means 21 stops the supply of air to the cathode (oxidant electrode) side, closes the purge valve 7 on the anode (fuel electrode) side, that is, stops the gas discharge in the anode, The operation of consuming oxygen on the cathode side is started by supplying hydrogen gas to the two electrodes and electrically connecting the two electrodes to extract current.

  Next, the pressure of the hydrogen gas supplied to the anode (anode pressure) is read from the pressure sensor 9 into the controller 20 (step S303). As a method for reading the anode pressure, the pressure after a lapse of a predetermined time from the start of hydrogen supply may be read, or the pressure may be continuously read immediately after the start of hydrogen supply.

  Next, based on the estimated parameter (X) relating to the read anode pressure, the amount of oxygen staying in the anode is estimated, and the disappearance time required to consume the amount of oxygen staying in the hydrogen gas input is estimated. The disappearance time is set as a time for continuing the start control (start control time), and the set start control time is set in, for example, a timer provided in the controller 20 (step S304).

  Subsequently, the activation control time set in the timer is counted down, and it is determined whether or not the count value has become 0 (step S305).

  Next, if the count value becomes 0 as a result of determination, it is determined that the start control is completed, and the system is switched from the start control state to the normal power generation control state by the start control / normal power generation control switching means 22 in the controller 20. Then, the compressor 11 and the air pressure regulating valve 12 are driven to shift to the normal power generation control, and the air supply to the cathode side is started (step S306).

  Thereafter, normal power generation control is started using the normal power generation control means 23 (step S307).

  Here, the necessity of executing start control when starting the fuel cell system will be described. When the fuel cell system is normally started without performing the above-described start control after being left for a long period of time, hydrogen gas is supplied to the anode side in the air atmosphere on both the anode side and the cathode side, and to the cathode side. Since air is supplied and both electrodes are electrically connected to take out current, a hydrogen / air interface is generated on the anode side in a state where the voltage is raised. For this reason, the corrosion reaction of the single carbon carrying the cathode side catalyst as shown below proceeds, and the deterioration of the fuel cell stack is promoted.

C + 2H ₂ O → CO ₂ + 4H ⁺ + 4e ⁻
Therefore, in order to suppress the above corrosion reaction at the time of start-up, even if the anode is in a mixed hydrogen / oxygen state, no voltage is generated, that is, oxygen in the cathode may be consumed. Therefore, in order to prevent the voltage from standing up, a fixed resistor or a load device is connected to the fuel cell stack at the time of start-up, and the current is taken out so that the voltage between the two electrodes becomes a predetermined voltage or less.

  Next, an exemplary embodiment of each of the above processing steps in the flowchart shown in FIG. 3 will be described.

Embodiment Example 1
In this embodiment example 1, in step S304 of FIG. 3, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary for disappearing the oxygen amount is set as the anode pressure. The relationship between the anode pressure and the amount of oxygen in the anode after the set predetermined time and the relationship between the anode pressure and the disappearance time of the oxygen remaining in the anode are obtained by conducting experiments in advance using an actual machine (in advance) (Actual machine confirmation), the obtained relationship is tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  When creating a table or map of the disappearance time, the actual machine is checked in two states, a state where oxygen is sufficiently retained in the anode and a state where it is not, and the map or table is interpolated between them. However, it is more preferable to confirm the actual device by changing the amount of oxygen in the anode.

  The start control / normal power generation control switching means 22 refers to the table or map based on the read anode pressure and calculates the amount of oxygen in the anode and the disappearance time.

  In Embodiment 1 like this, when hydrogen gas is supplied to the anode, a part of the supplied hydrogen gas disappears due to a chemical reaction with oxygen present in the anode, and the anode pressure fluctuates in the process. Therefore, the fluctuation amount of the anode pressure is correlated with the amount of oxygen existing in the anode. Using this correlation, the amount of oxygen present in the anode can be estimated from the behavior of the anode pressure. It is also possible to estimate the disappearance time until the amount of oxygen staying in the anode disappears.

  Thereby, it is possible to appropriately determine the time for ending the start-up control, and it is possible to shift the system from the start-up control state to the normal power generation state in a state where oxygen on the anode side has disappeared. Therefore, it is possible to prevent the cathode from deteriorating and optimize the time from the start to the start of power generation.

  On the other hand, as a conventionally known method for determining the end of start-up, there is a method based on the voltage of the fuel cell stack. Since the voltage is the difference between the anode potential and the cathode potential, it is based only on the anode potential (anode oxygen amount). However, since it is affected by the cathode potential (cathode oxygen amount), it is difficult to correctly determine the end of the start-up control.

  In addition, when determining the end of the start-up control when the total voltage value of the fuel cell stack reaches a predetermined value or less, there is a difference between the oxygen consumption rate in the anode and the oxygen consumption rate in the cathode, Since there is no direct correlation between the oxygen disappearance time in the anode and the total voltage, it is difficult to determine an appropriate end. Therefore, the relationship between the total voltage and the amount of oxygen in the anode is experimentally measured, and the end time of the start-up control is set with a certain margin.

  However, in a fuel cell system mounted on a vehicle, if a deviation occurs in the relationship between the amount of oxygen and the voltage in the anode / cathode, the deterioration of the fuel cell stack cannot be suppressed if the start-up control is short. However, if the start control is long, the drivability is deteriorated by extending the start time.

  On the other hand, in the present invention, the amount of oxygen staying in the anode itself is estimated using only the existing system components, and the start end is determined according to the estimated amount of oxygen, thereby avoiding complication of the system. Therefore, it is possible to achieve both execution of suitable deterioration suppression control and optimization of the startup time.

Embodiment Example 2
In this embodiment example 2, in step S302 of FIG. 3, the anode pressure control means 21A in the start-up control means 21 generates an anode pressure command value (control target value).

  In step S303, after the anode pressure of the pressure sensor 9 is read, the read anode pressure is compared with the anode pressure command value under the control of the anode pressure control means 21A, and the read pressure value matches the command value. Thus, the anode pressure is controlled by outputting an open / close signal to the hydrogen supply valve 5.

  In step S304, the anode pressure is an estimated parameter for estimating the amount of oxygen remaining in the anode and the disappearance time necessary to eliminate the oxygen amount, and the anode pressure after a predetermined time has elapsed after start control is started. The relationship between the anode and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of stagnant oxygen were obtained in advance using an actual machine (preliminary actual machine confirmation), and the obtained relation was tabulated and mapped. And stored in a storage device such as a ROM of the controller 20.

  The start control / normal power generation control switching means 22 refers to the table or map based on the read anode pressure and calculates the amount of oxygen in the anode and the disappearance time. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 2 as described above, the same effect as in Embodiment 1 above can be obtained. On the other hand, by controlling the anode pressure at the start-up control to the target value, hydrogen gas due to variations in system components can be obtained. Therefore, it is possible to suppress the variation in the input amount of the anode, and a stable behavior of the anode pressure can be obtained. Thereby, the estimation accuracy of the amount of oxygen in the anode and the disappearance time can be increased.

Embodiment Example 3
In the third embodiment, steps S302 and S303 in FIG. 3 are the same as in the second embodiment.

  In step S304, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time required to eliminate the oxygen amount is set as a differential pressure between the read anode pressure and the anode pressure command value, and after starting control is started. The relationship between the differential pressure and the amount of oxygen in the anode after the elapse of a predetermined time set in advance, and the relationship between the anode pressure and the disappearance time of stagnant oxygen are obtained by conducting experiments in advance using an actual machine. Confirmation), the obtained relationship is tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 calculates the differential pressure between the read anode pressure and the anode pressure command value, refers to the table or map based on the differential pressure, and determines the amount of oxygen in the anode and the disappearance time. Is calculated. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 3 like this, the same effect as in Embodiment 2 can be obtained.

(Embodiment example 4)
In the fourth embodiment, step S302 and step S303 in FIG. 3 are the same as in the second embodiment.

  In step S304, an estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time required to disappear the oxygen amount is integrated by integrating the differential pressure between the read anode pressure and the anode pressure command value. The relationship between the integrated value within the predetermined time range after the start of control and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of stagnant oxygen are obtained by conducting experiments using actual devices in advance (preliminary actual devices). Confirmation), the obtained relationship is tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 calculates an integrated value of the differential pressure between the read anode pressure and the anode pressure command value, refers to the table or map based on the integrated value, and determines the oxygen amount in the anode. As well as the disappearance time. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 4 as described above, the same effect as in Embodiment 2 can be obtained.

(Embodiment example 5)
In this embodiment example 5, step S302 and step S303 in FIG. 3 are the same as in the previous embodiment example 2.

  In step S304, the estimated amount of oxygen staying in the anode and the estimation parameter for estimating the disappearance time necessary for disappearing the oxygen amount are read as the anode pressure and the anode pressure command value read after a lapse of a predetermined time after starting the start control. The relationship between the maximum value after the elapse of a predetermined time after the start of the start-up control and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of stagnant oxygen were previously determined using an actual machine. An experiment is performed and obtained (preliminary actual machine confirmation), and the obtained relationship is tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 calculates the maximum value of the differential pressure between the read anode pressure and the anode pressure command value, refers to the above table or map based on the maximum value, and determines the oxygen amount in the anode. As well as the disappearance time. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 5 as described above, the same effect as in Embodiment 2 can be obtained.

(Embodiment example 6)
In this embodiment example 6, step S302 and step S303 in FIG. 3 are the same as in the previous embodiment example 2.

  In step S304, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary for disappearing the oxygen amount is set as the maximum value of the anode pressure read after the start control is started, The relationship between the oxygen amount and the relationship between the anode pressure and the disappearance time of the stagnation oxygen is obtained by conducting an experiment in advance using an actual machine (preliminary actual machine confirmation), and the obtained relationship is tabulated or mapped to the controller 20. And stored in a storage device such as a ROM.

  The start control / normal power generation control switching means 22 calculates the maximum value of the read anode pressure, and calculates the amount of oxygen in the anode and the disappearance time by referring to the table or map based on the maximum value. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 6 like this, the same effect as in Embodiment 2 can be obtained.

Embodiment Example 7
In this embodiment example 7, step S302 and step S303 in FIG. 3 are the same as in the previous embodiment example 2.

  In step S304, an estimated parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary to eliminate the oxygen amount is the arrival time until the anode pressure read after the start control starts reaches the anode pressure command value. The relationship between the arrival time and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of the remaining oxygen was determined in advance using an actual machine (preliminary actual machine confirmation). Prepared in a table or map and stored in a storage device such as a ROM of the controller 20.

  The start control / normal power generation control switching means 22 calculates the arrival time, refers to the table or map based on the arrival time, and calculates the amount of oxygen in the anode and the disappearance time. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 5 as described above, the same effect as in Embodiment 2 can be obtained.

(Embodiment example 8)
In this embodiment example 8, step S302 and step S303 in FIG. 3 are the same as in the previous embodiment example 2.

  In step S304, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary to eliminate the oxygen amount is the anode pressure increase rate, and the relationship between this increase rate and the oxygen amount in the anode, In addition, the relationship between the anode pressure and the disappearance time of the remaining oxygen is obtained by conducting an experiment in advance using an actual machine (preliminary actual machine confirmation), and the obtained relationship is tabulated or mapped to a storage device such as a ROM of the controller 20 Make sure to memorize it.

  The start control / normal power generation control switching means 22 calculates the pressure increase rate of the anode pressure by accumulating the anode pressure read until the anode pressure reaches the command value after starting the start for a predetermined time and differentiating it. Based on the pressure increase rate, the above table or map is referred to calculate the amount of oxygen in the anode and the disappearance time. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 8 as described above, the same effect as in Embodiment 2 can be obtained.

(Embodiment example 9)
In this embodiment example 9, step S302 and step S303 in FIG. 3 are the same as in the previous embodiment example 2.

  In step S304, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time required to disappear the oxygen amount is the average value of the pressure increase rate of the anode pressure or the variation in the pressure increase rate. The relationship between the value or variation and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of the remaining oxygen are obtained by conducting experiments using actual devices in advance (preliminary actual device confirmation), and the obtained relationships are tabulated. Or is mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 calculates the pressure increase rate of the anode pressure by accumulating the anode pressure read until the anode pressure reaches the command value after starting the start for a predetermined time and differentiating it. Thereafter, the average value or variation of the pressure increase rate is calculated, and the amount of oxygen in the anode and the disappearance time are calculated by referring to the table or map based on the average value or variation. The subsequent steps are the same as those in the first embodiment.

  In Embodiment 9 like this, the same effect as in Embodiment 2 can be obtained. On the other hand, as the amount of oxygen staying at the anode increases, the consumption of oxygen may become uneven, and in this case, the pressure increase behavior of the anode pressure is not always constant and becomes unstable. In such a case, by using the average value and variation of the pressure increase rate of the anode pressure as the estimation parameter, it is possible to obtain a good estimation accuracy even when the oxygen consumption is uneven.

(Embodiment Example 10)
In the tenth embodiment, step S302 and step S303 in FIG. 3 are the same as in the second embodiment.

  In step S304, an estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary to eliminate the oxygen amount is read after a predetermined time has elapsed after the read anode pressure reaches the anode pressure command value. It was determined that the relationship between the anode pressure and the amount of oxygen in the anode as well as the relationship between the anode pressure and the disappearance time of the remaining oxygen was obtained by conducting experiments using actual equipment in advance (confirmation in advance). These relationships are tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 refers to the table or map based on the anode pressure and calculates the amount of oxygen in the anode and the disappearance time. The subsequent steps are the same as those in the first embodiment.

  After the start control starts, the anode pressure decreases with the consumption of oxygen after the anode pressure reaches the command value. This is because the unreacted oxygen immediately after starting the start control is gradually consumed with hydrogen and consumed. As the oxygen decreases, the rate of decrease in the anode pressure decreases. By setting the anode pressure at this point as an estimation parameter, it is possible to obtain good estimation accuracy.

  In Embodiment 10 like this, the same effect as in Embodiment 2 can be obtained.

(Embodiment Example 11)
In this embodiment example 11, step S302 in FIG. 3 is the same as in the previous embodiment example 2.

  In step S303, after the anode pressure of the pressure sensor 9 is read, the read anode pressure is compared with the anode pressure command value under the control of the anode pressure control means 21A, and the read pressure value matches the command value. Thus, an open / close signal is output to the hydrogen supply valve 5 to control the anode pressure. When the read anode pressure matches the command value, the hydrogen supply valve 5 is closed and the supply of hydrogen gas to the anode is stopped.

  In step S304, an estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary to eliminate the oxygen amount is obtained in a state where hydrogen gas is pressurized and sealed in the anode by stopping the supply of hydrogen gas. The anode pressure read after a lapse of a predetermined time after the read anode pressure reaches the anode pressure command value, and the relationship between the anode pressure and the amount of oxygen in the anode, and the disappearance time of the accumulated oxygen pressure and the anode pressure The relationship is obtained by conducting an experiment using an actual machine in advance (preliminary actual machine confirmation), and the obtained relation is tabulated or mapped and stored in a storage device such as a ROM of the controller 20 in advance.

  The start control / normal power generation control switching means 22 refers to the table or map based on the anode pressure and calculates the amount of oxygen in the anode and the disappearance time. The subsequent steps are the same as those in the first embodiment.

  By using the behavior of the anode pressure in a state in which hydrogen gas is pressurized and sealed in the anode as an estimation parameter, the estimation accuracy of the anode oxygen amount can be increased as compared with the case where hydrogen gas is continuously supplied. On the other hand, since the supply of hydrogen gas is stopped when the anode pressure reaches the command value, there is a possibility that oxygen cannot be consumed by the supplied hydrogen gas depending on the amount of residual oxygen in the anode.

  Therefore, in the previous embodiment example 10 and this embodiment example 11, the embodiment example 2 is performed before the anode pressure after starting the start control reaches the command value to estimate the amount of remaining oxygen, and then It is determined whether or not the estimated oxygen amount can be consumed by the amount of hydrogen input until the anode pressure reaches the command value. If the oxygen amount cannot be consumed, the previous embodiment example 10 in which hydrogen gas is continuously input is adopted. If it can be consumed, this Embodiment 11 may be adopted.

(Embodiment example 12)
In this twelfth embodiment, activation control is executed according to the flowchart shown in FIG. 4 instead of the flowchart shown in FIG. The flowchart shown in FIG. 4 executes steps S401 and S402 instead of steps S304 and S305 in FIG. 3 with respect to the flowchart shown in FIG. 3, and the other steps S301 to S303 and S306 to S307 are the same as those in FIG. .

  Step S302 of FIG. 4 is the same as that of the previous embodiment example 2, and step S303 is the same as the previous embodiment example 11.

  In step S401, the amount of oxygen remaining in the anode is calculated in the same manner as in the eleventh embodiment.

  Thereafter, in step S402, it is determined whether or not oxygen in the anode has been consumed. In this method, hydrogen gas is pressurized and sealed in the anode, and the anode pressure per unit time when oxygen in the anode is consumed after the read anode pressure reaches the anode pressure command value. The relationship between the fluctuation (decrease rate) of the anode and the amount of oxygen in the anode is obtained by conducting an experiment in advance using an actual machine (preliminary actual machine confirmation), and the obtained relation is tabulated or mapped and stored in the ROM of the controller 20 or the like. Prepare it by storing it in the device.

  The start control / normal power generation control switching means 22 calculates the rate of decrease in anode pressure per unit time after the read anode pressure reaches the anode pressure command value, and refers to the table or map based on this rate of decrease. Then, it is determined whether or not oxygen in the anode has been lost.

As a result of the determination, when it is estimated that the fluctuation of the anode pressure falls below a predetermined value and the change in the rate of decrease in the anode pressure is hardly seen and oxygen corresponding to the input hydrogen gas is consumed, The process proceeds to step S306.

  In Embodiment 12 like this, the same effect as in Embodiment 11 above can be obtained.

  FIG. 5 is a diagram showing responses (time changes) of various quantities when the fuel cell system in the power generation state is stopped and restarted immediately. FIG. 5 (a) shows the cathode gas concentration and FIG. 5 (b) shows the cathode gas concentration. The anode gas concentration, FIG. 10C shows the electrode potential and the potential difference between the electrodes, and FIG. 11D shows the anode gas concentration.

  In FIG. 5, before starting, the anode is in a hydrogen atmosphere and the cathode is in a nitrogen atmosphere. Therefore, both the anode and cathode electrodes are near the hydrogen potential, and the voltage is low. In this state, when the start-up is started, oxygen does not exist in the anode and the cathode, so there is no current consumption of oxygen in the cathode due to power generation and no current consumption of oxygen in the anode due to chemical reaction. As a result, the total amount of hydrogen input is used for increasing the anode pressure, so that the anode pressure increasing rate is increased.

  FIG. 6 is a diagram showing responses (time changes) of various amounts when the fuel cell system in a power generation state is stopped and left standing and the cathode and the anode are sufficiently started from an air atmosphere state. (B) shows the anode gas concentration, (c) shows the electrode potential, the potential difference between the electrodes, and (d) shows the anode gas concentration.

  In FIG. 6, since both the anode and the cathode are at the air potential, the potential difference between the electrodes is zero. Here, when the hydrogen gas and air are simultaneously supplied and started without adopting the start control of the present invention, the cathode maintains the air potential by the start of hydrogen supply and the start of air supply, while the anode Gradually shift to hydrogen potential. For this reason, a potential difference is generated and this potential difference continues, a hydrogen / air gas interface is generated on the anode side, and deterioration of the fuel cell stack 1 is promoted.

  On the other hand, the oxygen disappearance in the anode may be determined based on the anode pressure after waiting for the oxygen in the anode to completely disappear from the start of the hydrogen supply. By estimating the time until the oxygen in the anode completely disappears from the behavior, it is possible to reduce the time for start-up control and optimize it. In this case, the determination accuracy can be improved by continuously monitoring the anode pressure to determine the disappearance of oxygen.

  The behavior of each quantity shown in FIG. 5 and FIG. 6 is experimentally confirmed with an actual machine, and based on the data collected at that time, the table used in each of the above embodiments and the examples described below A map is created.

  FIG. 7 is a diagram showing a detailed change in FIG. 5 (d) and FIG. 6 (d). In FIG. 7, reference A indicates details of FIG. 5D, and reference B indicates details of FIG. 6D.

  At the time of starting immediately after the stop, since there is no oxygen in the anode and the cathode, the total amount of hydrogen used is used for increasing the anode pressure, so that the pressure rises sharply. On the other hand, at the time of start-up after standing down, since a large amount of oxygen is present in the anode and cathode, most of the hydrogen to be charged is involved in the chemical reaction with oxygen, so it is used to increase the pressure in the anode. Since the amount of hydrogen generated is relatively small, the rise in pressure is delayed compared to the start immediately after the stop, and becomes gentle.

  In FIG. 7, there is a correlation between the response of the actual pressure of the anode to the command value (control target value) of the anode pressure and the amount of oxygen in the anode, and the first and second embodiments 1 and 2 use this correlation. is there.

  Further, when controlling the anode pressure, when the anode pressure matches the command value, the valve opening of the hydrogen supply valve 5 is reduced to reduce the supply amount of hydrogen gas, but the anode pressure overshoots due to a response delay. Exceeds the command value. Therefore, it is possible to estimate the amount of oxygen even when the anode pressure reaches the maximum value or when the anode pressure reaches the command value, and the above-described Embodiments 6 and 7 use this relationship.

  In addition, since there is a difference in the rising speed of the pressure increase in accordance with the amount of oxygen in the pressure increase process of the anode pressure, it is possible to estimate the amount of oxygen based on this pressure increase rate. Aspect examples 8 and 9.

  Even after the anode pressure is increased, the total amount of oxygen in the anode is not completely consumed, and the hydrogen / oxygen mixed gas circulates in the anode circulation path while gradually decreasing the oxygen concentration. Based on the decreasing rate (decreasing rate) of the anode pressure after reaching it, it becomes possible to estimate the amount of staying oxygen, and this example is used in the above-mentioned Embodiment Examples 10, 11, and 12.

  FIG. 8 is a diagram showing the response (time change) of the pressure difference (ΔP) between the measured anode pressure and the command value. By adopting the pressure difference, the integrated value of the pressure difference for a predetermined time shown in FIG. 8 or the maximum value of the pressure difference as the estimation parameter, it is possible to improve the estimation accuracy. Embodiment examples 3, 4 and 5.

  As described above, in Example 1 of Embodiments 1 to 12 above, when starting control for taking out current is performed, the amount of oxygen staying in the anode is estimated based on the behavior of the fuel gas pressure. Thus, the amount of oxygen that remains can be estimated appropriately.

  By setting the end time for ending the start-up control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  When the pressure of the fuel gas supplied to the fuel cell is controlled to the target value during start-up control, the oxygen amount is estimated and the end time is set, so that stable operation is possible regardless of variations in hydrogen input due to component variations. It is possible to appropriately estimate the amount of oxygen present in the anode from the measured anode pressure behavior, and to set the control execution time until the residual oxygen amount in the anode disappears based on the appropriately estimated amount of oxygen. it can.

  Based on the pressure difference between the target pressure value and the detected value (actual pressure), the oxygen amount is estimated and the end time is set so that it exists in the anode based on the difference between the target pressure and the actual pressure. The control execution time until the residual oxygen amount in the anode disappears can be set based on the appropriately estimated oxygen amount.

  Based on the integrated value of the differential pressure between the target value of the pressure and the detected value (actual pressure), the oxygen amount is estimated and the end time is set. The control execution time until the residual oxygen amount in the anode disappears can be set based on the appropriately estimated oxygen amount, which can appropriately estimate the oxygen amount existing in the anode.

  Based on the maximum value of the differential pressure between the target pressure value and the detected value (actual pressure), the oxygen amount is estimated and the end time is set. The amount of oxygen present in the anode can be appropriately estimated, and the control execution time until the amount of residual oxygen in the anode disappears can be set based on the appropriately estimated amount of oxygen.

  Based on the time to reach the maximum value of the differential pressure between the target pressure value and the detected value (actual pressure), the oxygen amount is estimated and the end time is set. The amount of oxygen present in the anode can be appropriately estimated from the time until reaching the maximum difference, and the control execution time until the residual oxygen amount in the anode disappears based on the appropriately estimated amount of oxygen Can be set.

  After starting the start control, the fuel gas pressure is estimated and the end time is set based on the time until the detected value (actual pressure) of the fuel gas pressure reaches the target value. The amount of oxygen present in the anode can be appropriately estimated from the time until the actual pressure of the gas reaches the target pressure, and the residual oxygen amount in the anode disappears based on the amount of oxygen estimated appropriately. The control execution time can be set.

  After starting the start-up control, the oxygen gas amount is estimated and the end time is set based on the fuel gas pressure increase rate until the detected value (actual pressure) of the fuel gas reaches the target value. The amount of oxygen present in the anode can be appropriately estimated from the pressure increase rate of the fuel gas from the start of supply until the actual pressure of the fuel gas reaches the target pressure. Based on the amount of oxygen estimated appropriately, The control execution time until the residual oxygen amount disappears can be set.

  Estimate the oxygen amount and set the end time based on the average value or variation of the fuel gas pressure increase rate until the detected value (actual pressure) of the fuel gas reaches the target value after starting the start control Thus, even when the pressure increase of the fuel gas is not constant due to uneven oxygen consumption (the more oxygen the more), the amount of oxygen present in the anode can be estimated appropriately, The control execution time until the residual oxygen amount in the anode disappears can be set based on the appropriately estimated oxygen amount.

  The reason why the fuel gas pressure in the anode decreases after the detection value of the fuel gas pressure reaches the target value after the start control is started is that unreacted oxygen has gradually reacted immediately after the start control. Since the pressure decreasing tendency decreases as oxygen decreases, after starting control, the estimation and termination of the oxygen amount based on the behavior of the fuel gas pressure after the detected value of the fuel gas pressure reaches the target value The time can be set, the amount of oxygen present in the anode can be estimated appropriately, and the control execution time until the amount of residual oxygen in the anode disappears based on the amount of oxygen estimated appropriately Can be set.

  The reason why the fuel gas pressure in the anode decreases after the detection value of the fuel gas pressure reaches the target value after the start control is started is that unreacted oxygen has gradually reacted immediately after the start control. As the oxygen decreases, the tendency of the pressure to decrease decreases, so after starting the start-up control, the fuel gas supply is stopped after the detected value of the fuel gas pressure reaches the target value, and the behavior of the fuel gas pressure thereafter Based on this, the amount of oxygen can be estimated and the end time can be set, the amount of oxygen present in the anode can be estimated appropriately, and the amount of residual oxygen in the anode based on the amount of oxygen estimated appropriately The control execution time until disappearance can be set.

  The pressure of the fuel gas in the anode decreases after the pressure reaches the target value after the fuel gas pressure is increased to the specified pressure. The unreacted oxygen gradually reacts immediately after startup. This is because the tendency of the pressure drop to decrease as oxygen decreases, so that the fluctuation of the pressure in the anode hardly occurs when the amount of residual oxygen in the anode disappears. Therefore, after the fuel gas supply is stopped, when the pressure fluctuation falls below a predetermined value, it is estimated that the oxygen remaining in the anode has disappeared, and the start-up control can be terminated. The amount of oxygen present in the anode can be appropriately estimated, and the control execution time until the residual oxygen amount in the anode disappears can be set based on the appropriately estimated amount of oxygen.

  FIG. 9 is a diagram showing a configuration of a fuel cell system according to Embodiment 2 of the present invention. The structural features of the system of the second embodiment shown in FIG. 9 are different from those of the first embodiment shown in FIG. 1 in that the hydrogen gas flows between the pressure reducing valve 4 and the hydrogen supply valve 5 in the hydrogen gas supply path. Since the flow rate sensor 24 (flow rate detection means) for measuring the flow rate is provided and the others are the same as those in FIG. 1, the description thereof is omitted.

  The configuration of the control logic is the same as that of the first embodiment shown in FIG.

  Next, the operation of the fuel cell system according to the second embodiment will be described as an example with reference to FIG. FIG. 10 is a flowchart showing the operation at the start-up of the fuel cell system according to the second embodiment. The feature of the operation of the second embodiment shown in FIG. 10 is that, in place of step S303 in the flowchart shown in FIG. 3, the process of reading the hydrogen flow rate into the controller 20 is performed in addition to the process executed in step S303. Step S501 is executed, instead of Steps S304 and S305, Step S502 for calculating the amount of oxygen in the anode and Step S503 for determining whether to switch from the start control to the normal power generation control are executed. This is the same as FIG.

  In the second embodiment, when the anode pressure is controlled to a command value (target pressure) similar to that in the first embodiment, if the oxygen staying in the anode is consumed and the increase in the anode pressure is completed. Since the supply flow rate of hydrogen gas is reduced, the amount of oxygen in the anode is estimated by determining whether the flow rate has become a predetermined value or less, or the time until the flow rate has become a predetermined value or less, and the consumption of oxygen has ended. Can be determined.

  In addition, the amount of hydrogen input is obtained by time integration of the hydrogen flow rate, and the amount of oxygen in the anode and the end of oxygen consumption are determined based on the relationship between the amount of oxygen in the anode and the amount of hydrogen consumed before oxygen is consumed. You can also Furthermore, when the supply amount of hydrogen gas is decreased, an operation of reducing the valve opening degree of the hydrogen supply valve 5 is executed. Therefore, when the valve opening degree or the hydrogen supply valve 5 is controlled to be opened and closed by the PWM control method. By using the duty ratio of the open / close signal for controlling the open / close, it can be calculated in the same manner as described above instead of the flow rate.

  Next, an exemplary embodiment of steps S501 to S503 in the flowchart shown in FIG. 10 will be described.

Embodiment Example 1
In this embodiment example 1, step S501 reads the anode pressure signal of the pressure sensor 9 and the flow rate signal measured by the flow rate sensor 24, and then reads the read anode pressure and anode under the control of the anode pressure control means 21A. As compared with the pressure command value, an open / close signal is output to the hydrogen supply valve 5 so that the read pressure value matches the command value.

  In step S502, the amount of oxygen remaining in the anode and the estimated parameter for estimating the disappearance of the oxygen amount are the hydrogen flow rate measured by the flow sensor 24 after startup, the relationship between the hydrogen flow rate and the oxygen amount in the anode, and hydrogen The relationship between the flow rate and the time until the stagnant oxygen disappears is obtained by conducting an experiment in advance using an actual machine (preliminary actual machine confirmation), and the obtained relation is tabulated or mapped and stored in the ROM of the controller 20 or the like. Prepare it by storing it in the device.

  The start control / normal power generation control switching means 22 refers to the table or map based on the read hydrogen flow rate and calculates the oxygen amount in the anode.

  In step S503, the flow rate of hydrogen supplied to the anode decreases with the consumption of oxygen, and when the hydrogen flow rate falls below a preset determination value (a value that is estimated to have consumed oxygen in actual machine confirmation) It is estimated that oxygen in the anode has been consumed. Alternatively, referring to the table or map, the time to reach the determination value (the time until oxygen disappears) is estimated based on the hydrogen flow rate, and after the estimated time has elapsed, the start control is changed to the normal power generation control. It is determined that it can be switched. The subsequent steps are the same as in the first embodiment.

  As described above, in embodiment example 1 in embodiment 2, it is possible to estimate the amount of retained oxygen in the anode in the anode based on the hydrogen flow rate, and determine the end of start-up control according to the estimated amount of oxygen. By doing so, it is possible to achieve both the execution of suitable deterioration suppression control and the shortening of the startup control time while avoiding complication of the system.

Embodiment Example 2
In this embodiment example 2, after reading the anode pressure signal of the pressure sensor 9 and the flow rate signal measured by the flow rate sensor 24, step S501 reads the read anode pressure and anode under the control of the anode pressure control means 21A. As compared with the pressure command value, an open / close signal is output to the hydrogen supply valve 5 so that the read pressure value matches the command value.

  In step S502, the oxygen amount staying in the anode and the estimation parameter for estimating the disappearance of the oxygen amount are used as the opening / closing signal of the hydrogen supply valve 5 after startup corresponding to the hydrogen flow rate supplied into the anode. The relationship between the amount of oxygen in the anode and the hydrogen flow rate and the time until the remaining oxygen disappears are experimentally determined in advance using actual equipment (preliminary actual equipment confirmation), and the relationship obtained is tabulated. Or is mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 refers to the table or map based on the read opening / closing signal and calculates the oxygen amount in the anode.

  In step S503, the flow rate of hydrogen supplied to the anode decreases with the consumption of oxygen, and when the hydrogen flow rate falls below a preset determination value (a value that is estimated to have consumed oxygen in actual machine confirmation) It is estimated that oxygen in the anode has been consumed. Alternatively, referring to the table or map, the time (time until oxygen disappears) until reaching the determination value is estimated based on the open / close signal, and after the estimated time has elapsed, the start control is changed to the normal power generation control. It is determined that it can be switched. The subsequent steps are the same as in the first embodiment.

  As described above, in Embodiment 2 of Embodiment 2, the same effect as Embodiment 1 of Embodiment 2 can be obtained based on the open / close signal of the hydrogen supply valve 5.

  FIG. 11A is a diagram showing a response (time change) of the hydrogen flow rate in the first embodiment example, and FIG. 11B is a response (time) of the valve opening of the hydrogen supply valve 5 in the second embodiment example. FIG. In both figures, the state after activation in the hydrogen atmosphere and the cathode in the nitrogen atmosphere is indicated by symbol A, and the state after activation in the air atmosphere is indicated by symbol B for both the anode and cathode.

  In FIG. 11, when oxygen in the anode reacts with the supplied hydrogen and oxygen is gradually consumed, the flow rate of the supplied hydrogen gas decreases and the valve opening of the hydrogen supply valve 5 is narrowed. Therefore, it is possible to estimate that the oxygen in the anode has been consumed by determining that these are below the determination value.

Embodiment Example 3
In this embodiment example 3, after reading the anode pressure signal of the pressure sensor 9 and the flow rate signal measured by the flow rate sensor 24, step S501 reads the read anode pressure and anode under the control of the anode pressure control means 21A. As compared with the pressure command value, an open / close signal is output to the hydrogen supply valve 5 so that the read pressure value matches the command value.

  In step S502, the amount of oxygen staying in the anode and the estimation parameter for estimating the disappearance of the oxygen amount are set as an integral value (valve of the opening / closing signal of the hydrogen supply valve 5 after startup corresponding to the flow rate of hydrogen supplied into the anode. The relationship between the integrated value of the opening / closing signal and the amount of oxygen in the anode, and the relationship between the hydrogen flow rate and the time until the stagnant oxygen disappears are determined in advance using an actual machine. (Preliminary actual machine confirmation) The obtained relationships are tabulated or mapped and stored in a storage device such as a ROM of the controller 20 for preparation.

  The start control / normal power generation control switching means 22 calculates the integral value based on the read opening / closing signal, and refers to the table or map based on the calculated integral value to calculate the oxygen amount in the anode.

  In step S503, the flow rate of hydrogen supplied to the anode decreases with the consumption of oxygen, and when the hydrogen flow rate falls below a preset determination value (a value that is estimated to have consumed oxygen in actual machine confirmation) It is estimated that oxygen in the anode has been consumed. Alternatively, referring to the table or map, the time to reach the determination value (time until oxygen disappears) is estimated based on the integral value, and the normal power generation control is started from the start control after the estimated time has elapsed. It is determined that it can be switched to. The subsequent steps are the same as in the first embodiment.

  As described above, in the third embodiment example in the second embodiment, the supply hydrogen flow rate can be estimated from the integral value of the open / close signal of the hydrogen supply valve 5, that is, the integral value of the valve opening degree. 1 can be obtained.

  As described above, in the second embodiment of the first to third embodiments, the amount of oxygen staying in the anode is estimated based on the behavior of the fuel gas pressure when the start-up control for taking out the current is performed. Thus, the amount of oxygen that remains can be estimated appropriately.

  By setting the end time for ending the start-up control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  By estimating the amount of oxygen and setting the end time based on the behavior of the flow rate of fuel gas after the start of fuel gas supply, the amount of oxygen present in the anode can be estimated appropriately and estimated appropriately. A control execution time until the residual oxygen amount in the anode disappears can be set on the basis of the oxygen amount.

  Based on the time until the flow rate of the fuel gas falls below a predetermined flow rate, it is possible to estimate the amount of oxygen staying in the anode, it is possible to appropriately estimate the amount of oxygen present in the anode, The control execution time until the residual oxygen amount in the anode disappears can be set based on the appropriately estimated oxygen amount.

  By estimating the amount of oxygen remaining in the anode based on the time until the valve opening of the pressure regulating valve is reduced to the predetermined valve opening, the supply of fuel gas is reduced from the decrease in the valve opening of the pressure regulating valve. The amount of oxygen present in the anode can be properly estimated, and the control execution time until the residual oxygen amount in the anode disappears is set based on the appropriately estimated oxygen amount. be able to.

  Based on the integral value of the time until the valve opening of the pressure regulating valve is reduced to the predetermined valve opening, the amount of oxygen staying in the anode is estimated, so that the flow rate of fuel gas from the valve opening area of the pressure regulating valve Since the amount of fuel gas passing through is obtained from the integral value of the valve opening, the amount of oxygen present in the anode can be estimated appropriately. By setting the end time for ending the startup control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  FIG. 12 is a diagram showing the configuration of the control logic (program) stored in the storage device or the like of the controller 20 in Embodiment 3 of the present invention. The control logic of the third embodiment is characterized in that the flow rate of hydrogen gas supplied to the anode is controlled instead of the anode pressure control means 21A as compared with the control logic of the first embodiment shown in FIG. The activation control means 21 is configured to include the anode flow rate control means 21B, and the others are the same as those in FIG. The system configuration is the same as that of the second embodiment shown in FIG.

  In this third embodiment, unlike the case of estimating the oxygen amount in the anode while the anode pressure is controlled as in the first and second embodiments, the supply amount of hydrogen supplied to the anode is controlled. Estimate the amount of oxygen in the anode. In such control, since the pressure increase behavior of the anode pressure varies depending on the amount of oxygen in the anode, the time until the oxygen amount and the staying oxygen amount are consumed is estimated based on the pressure increase behavior. I have to.

  Next, the operation of the fuel cell system according to the third embodiment will be described as an example with reference to FIG. FIG. 13 is a flowchart showing the operation at the start-up of the fuel cell system according to the third embodiment. The feature of the operation of the third embodiment shown in FIG. 13 is that a hydrogen flow rate command value is generated instead of the anode pressure command value in place of step S302 in the flowchart shown in FIG. Step S601 for performing the same process as S302 is executed, and instead of Step S501, Step S602 for performing a process of reading the hydrogen flow rate and controlling the anode flow rate is executed, and instead of Step S502, the oxygen amount in the anode is set. Step S603 is calculated, and step S604 is executed to determine whether to switch from start-up control to normal power generation control in the state where the hydrogen flow rate is controlled instead of step S503. The description is omitted because it is the same as FIG.

  Next, an exemplary embodiment of steps S601 to S604 in the flowchart shown in FIG. 13 will be described.

Embodiment Example 1
In this embodiment example 1, in step S601, the activation control means 21 stops the supply of air gas to the cathode, closes the purge valve 7 of the anode, that is, stops the gas discharge in the anode, The operation of consuming oxygen at the cathode is started by supplying gas and electrically connecting both electrodes to extract current. Further, a command value (control target value) of the flow rate (anode flow rate) of the hydrogen gas supplied to the anode is generated by the anode flow rate control unit 21B in the activation control unit 21.

  In step S602, after the anode flow rate detected by the flow rate sensor 24 is read, the read flow rate is converted into a command value by comparison with the read anode flow rate and the anode flow rate command value under the control of the anode flow rate control means 21B. An open / close signal is output to the hydrogen supply valve 5 so as to match. Further, the anode pressure detected by the pressure sensor 9 is read into the controller 20 when the anode flow rate is controlled to become the command value.

  In step S603, the anode pressure is an estimation parameter for estimating the amount of oxygen remaining in the anode and the disappearance time required to eliminate the oxygen amount, and the anode pressure after a predetermined time has elapsed after start control is started. The relationship between the anode and the amount of oxygen in the anode, and the relationship between the anode pressure and the disappearance time of stagnant oxygen were obtained in advance using an actual machine (preliminary actual machine confirmation), and the obtained relation was tabulated and mapped. And stored in a storage device such as a ROM of the controller 20.

  The start control / normal power generation control switching means 22 calculates the oxygen amount in the anode by referring to the table or map based on the read anode pressure.

  In step S604, the startup control / normal power generation control switching means 22 refers to the table or map based on the read anode pressure, and calculates the disappearance time of the oxygen amount in the anode. Thereafter, this disappearance time is set as a time (startup control time) for continuing the start control, and the set start control time is set, for example, in a timer provided in the controller 20. Subsequently, the activation control time set in the timer is counted down to determine whether or not the count value has become 0. When the count value becomes 0, it is determined that the activation control has been completed, and normal power generation is performed from the activation control. It is determined that the control can be switched.

  Thus, in Embodiment Example 1 of Example 3 above, the amount of oxygen staying at the anode and its disappearance time are determined based on the anode pressure under the control of controlling the flow rate of hydrogen supplied to the anode. Thus, the same effects as those of the first and second embodiments can be obtained.

Embodiment Example 2
In the second embodiment, step S601 is the same as the first embodiment in the third embodiment.

  In step S602, after the anode flow rate detected by the flow rate sensor 24 is read, under the control of the anode flow rate control means 21B, the read anode flow rate is compared with the anode flow rate command value. An open / close signal is output to the hydrogen supply valve 5 so as to match the above.

  In step S603, the estimation parameter for estimating the amount of oxygen staying in the anode and the disappearance time necessary for disappearing the oxygen amount is obtained by integrating the integral value of the flow rate measured by the flow rate sensor 24 after the start control is started (total supply). ), And the relationship between the integrated value of this flow rate and the time until the oxygen in the anode disappears is obtained in advance using an actual machine (preliminary actual machine confirmation), and the obtained relation is tabulated or mapped. And stored in a storage device such as a ROM of the controller 20.

  The start control / normal power generation control switching means 22 calculates an integral value of the flow rate measured by the flow rate sensor 24 after the start control is started, and refers to the above table or map based on the integral value of the flow rate so that Calculate the amount of oxygen.

  In step S604, referring to the table or map, it is determined whether or not the integrated value of the flow rate has reached a predetermined determination value. If it has been reached, hydrogen sufficient to consume oxygen is supplied. It is estimated that oxygen has been consumed, and it is determined that the start control is completed and the start control can be switched to the normal power generation control. Here, the determination value is set in advance by checking the actual machine as the hydrogen amount estimated to have consumed oxygen in the anode.

  In Embodiment 2 like this, the same effect as in Embodiment 1 of Embodiment 3 can be obtained.

  FIG. 14 is a diagram showing the response of the hydrogen flow rate and the response of the anode pressure when the command value (target value) of the flow rate of hydrogen supplied to the anode is given in steps, and FIG. FIG. 4B shows the response of the anode pressure immediately after the stop (indicated by symbol A) and after leaving the stop (indicated by reference symbol B).

  When starting immediately after shutdown, since the anode-cathode gas state is startup from a hydrogen-nitrogen atmosphere, there is no oxygen in the anode and cathode, so the total amount of hydrogen to be input is used to increase the anode gas pressure. The rise in pressure is steeper compared to the case where the pressure rises after stopping. On the other hand, at the time of restart after standing down, since a large amount of oxygen is present in the anode and cathode, most of the hydrogen gas that is input is involved in the chemical reaction with oxygen, so it is used to increase the pressure in the anode. The amount of hydrogen generated is small compared to the start immediately after the stop, and the rise in pressure becomes gentle compared to the start immediately after the stop.

  Further, if the supply of hydrogen is stopped in the middle of the start-up control, the increase in the hydrogen pressure is stopped simultaneously with the supply stop, so that the reached hydrogen pressure differs due to the excessive amount of oxygen in the anode.

  As described above, in the third embodiment of the first and second embodiments, the amount of oxygen staying in the anode is estimated based on the behavior of the fuel gas pressure when starting control for extracting current is performed. Thus, the amount of oxygen that remains can be estimated appropriately.

  By setting the end time for ending the start-up control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  Based on the behavior of the pressure of the fuel gas when the flow rate of the fuel gas is controlled to the target value by the flow rate control means, it becomes possible to estimate the amount of oxygen staying in the anode, and while controlling the flow rate of the fuel gas, Since the fuel gas pressure response at that time can be monitored, the amount of oxygen present in the anode can be estimated appropriately. Further, by setting the end time for ending the start-up control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  When the integral value of the flow rate of the fuel gas reaches a predetermined value, it is possible to determine the amount of hydrogen input from the flow rate and supply time of the fuel gas by estimating that the oxygen remaining in the anode has disappeared. The amount of oxygen can be appropriately estimated from the amount of hydrogen input. By setting the end time for ending the start-up control based on the oxygen amount appropriately estimated in this way, the control execution time until the residual oxygen amount in the anode disappears can be set.

  Next, a fourth embodiment of the present invention will be described. The feature of the fourth embodiment is that it is implemented in combination with the first to third embodiments, calculates the amount of hydrogen consumed by power generation based on the generated current, and stays in the anode from the consumed hydrogen amount. The amount of oxygen to be estimated is estimated, and the amount of oxygen estimated in the first to third embodiments is corrected in consideration of the estimated amount of oxygen.

  First, in step S302 of FIG. 3, FIG. 4, FIG. 10, and step S601 of FIG. 13, in addition to the processing performed in each of steps S302 and S601, the activation control means 21 determines the generated current generated by the fuel cell stack 1. A command value is generated and applied to the power manager 16, and the power manager 16 extracts a current from the fuel cell stack 1 based on the command value.

  3, FIG. 4, step S <b> 501 in FIG. 10, and step S <b> 602 in FIG. 13, the controller 20 reads the current value measured by the power manager 16. The start control / normal power generation control switching means 22 calculates the amount of hydrogen consumed by power generation (QH2, c) using the following conversion formula based on the read current value.

(Equation 1)
QH2, c = Q × Vm × CN / (2 × F)
Here, Vm is the molar volume of 22.414 [NL / mol], CN is the number of cells constituting the fuel cell stack 1 [sheets], and F is the Faraday constant of 96485 [C / mol]. , Q is the charge amount [C], and is expressed as Q = I × t (I is current [A], t is time [s]).

  Thereafter, an oxygen amount in the anode corresponding to the consumed hydrogen amount is calculated with reference to a map or table showing the relationship between the consumed hydrogen amount and the oxygen amount prepared and stored in advance by checking the actual machine. The oxygen amount estimated in the first to third embodiments is corrected using the oxygen amount estimated in this way and an existing appropriate correction method.

  As described above, in Example 4 described above, when starting control for extracting current is performed, the amount of oxygen that remains in the anode is estimated by estimating the amount of oxygen that remains in the anode based on the behavior of the fuel gas pressure. Can be estimated.

  By setting the end time for ending the start-up control based on the appropriately estimated oxygen amount, the control execution time until the residual oxygen amount in the anode disappears can be set.

  Based on the current value detected by the current detection means, the consumption amount of the fuel gas consumed by taking out the current at the time of startability is calculated, and the oxygen amount estimated based on the obtained consumption amount of the fuel gas is calculated. It becomes possible to correct | amend and can improve the estimation precision of oxygen amount.

It is a figure which shows the structure of the fuel cell system which concerns on Example 1 of this invention. It is a figure which shows the structure of the control logic contained in the controller which concerns on Example 1 of this invention. It is a flowchart which shows the operation | movement procedure which concerns on Example 1 of this invention. It is a flowchart which shows the other operation | movement procedure which concerns on Example 1 of this invention. It is a figure which shows the behavior of each quantity which concerns on Example 1 of this invention. It is a figure which shows the behavior of each quantity which concerns on Example 1 of this invention. It is a figure which shows the detailed behavior of the anode pressure which concerns on Example 1 of this invention. It is a figure which shows the behavior of the difference of the anode pressure which concerns on Example 1 of this invention, and a target value. It is a figure which shows the structure of the fuel cell system which concerns on Example 2 of this invention. It is a flowchart which shows the operation | movement procedure which concerns on Example 2 of this invention. It is a figure which shows the behavior of the hydrogen flow volume and valve opening degree which concern on Example 2 of this invention. It is a figure which shows the structure of the control logic contained in the controller which concerns on Example 2 of this invention. It is a flowchart which shows the operation | movement procedure which concerns on Example 3 of this invention. It is a figure which shows the behavior of the hydrogen flow volume and anode pressure which concern on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 2 ... Hydrogen tank 3 ... Hydrogen tank main valve 4 ... Pressure-reducing valve 5 ... Hydrogen supply valve 6 ... Hydrogen circulation pump 7 ... Purge valve 8 ... Dilution device 9, 13 ... Pressure sensor 10 ... Temperature sensor 11 ... Compressor DESCRIPTION OF SYMBOLS 12 ... Air pressure regulating valve 14 ... Temperature sensor 15 ... Voltage sensor 16 ... Power manager 17 ... Secondary battery 18 ... Battery controller 19 ... Atmospheric pressure sensor 20 ... Controller 21 ... Start-up control means 21A ... Anode pressure control means 21B ... Anode flow control Means 22 ... Startup control / normal power generation control switching means 23 ... Normal power generation control means 24 ... Flow rate sensor

Claims (22)

In a fuel cell system including a fuel cell that generates power by an electrochemical reaction between a fuel gas supplied to the fuel electrode by the fuel gas supply means and an oxidant gas supplied to the oxidant electrode by the oxidant gas supply means,
Pressure detecting means for detecting the pressure of the fuel gas at the fuel electrode;
Discharging means for discharging unused fuel gas supplied to the fuel cell to the outside of the fuel cell;
Current extraction means for extracting the current obtained by the fuel cell from the fuel cell;
Control means for controlling supply of fuel gas by the fuel gas supply means, supply of oxidant gas by the oxidant gas supply means, discharge of fuel gas by the discharge means, and extraction of current by the current extraction means ,
The control means supplies the fuel gas by the fuel gas supply means in a state where the supply of the oxidant by the oxidant supply means and the discharge of the fuel gas by the discharge means are stopped when the system is started, and the current extraction A fuel cell system that estimates the amount of oxygen staying in the fuel electrode based on the behavior of the fuel gas pressure detected by the pressure detection means when performing start-up control for extracting current by the means. The control means sets an end time for ending the start control based on the estimated oxygen amount.
A fuel cell system. The control means includes pressure control means for controlling the pressure of the fuel gas supplied to the fuel cell, and the pressure of the fuel gas supplied to the fuel cell by the pressure control means during the start-up control is set to a target value. 3. The fuel cell system according to claim 1, wherein when the pressure increase control is performed, the oxygen amount is estimated or the end time is set. 4. 4. The fuel cell system according to claim 3, wherein the oxygen amount is estimated or the end time is set based on a differential pressure between the target value and a detected value detected by the pressure detecting means. 4. The fuel according to claim 3, wherein the oxygen amount is estimated or the end time is set based on an integral value of a differential pressure between the target value and a detected value detected by the pressure detecting means. Battery system. 4. The fuel according to claim 3, wherein the oxygen amount is estimated or the end time is set based on a maximum value of a differential pressure between the target value and a detected value detected by the pressure detecting means. Battery system. After the start control is started, the oxygen amount is estimated or the end time is set based on the time until the maximum value of the differential pressure between the target value and the detected value detected by the pressure detecting means is reached. The fuel cell system according to claim 3, wherein the fuel cell system is performed. The oxygen amount is estimated or the end time is set based on a time until the detection value detected by the pressure detection means reaches the target value after starting the activation control. Item 4. The fuel cell system according to Item 3. The oxygen amount is estimated or the end time is set based on the pressure increase rate of the fuel gas until the detection value detected by the pressure detection means reaches the target value. Fuel cell system. The oxygen amount is estimated or the end time is set based on an average value or variation in the pressure increase rate of the fuel gas until the detection value detected by the pressure detection means reaches the target value. The fuel cell system according to claim 3. After the start control is started, the oxygen amount is estimated or the end time is set based on the behavior of the fuel gas pressure after the detection value detected by the pressure detection means reaches the target value. The fuel cell system according to claim 3. After the start control is started, the supply of fuel gas is stopped after the detection value detected by the pressure detection means reaches the target value, and the oxygen amount is estimated based on the behavior of the fuel gas pressure thereafter. The fuel cell system according to claim 3, wherein the end time is set. After the supply of fuel gas is stopped, when the fluctuation in pressure detected by the pressure detection means falls below a predetermined value, it is estimated that the oxygen remaining in the fuel electrode has disappeared and the start-up control is terminated. The fuel cell system according to claim 12. In a fuel cell system including a fuel cell that generates power by an electrochemical reaction between a fuel gas supplied to the fuel electrode by the fuel gas supply means and an oxidant gas supplied to the oxidant electrode by the oxidant gas supply means,
Pressure detecting means for detecting the pressure of the fuel gas at the fuel electrode;
Discharging means for discharging unused fuel gas supplied to the fuel cell to the outside of the fuel cell;
Current extraction means for extracting the current obtained by the fuel cell from the fuel cell;
Flow rate detecting means for detecting the flow rate of the fuel gas supplied to the fuel cell;
Control means for controlling supply of fuel gas by the fuel gas supply means, supply of oxidant gas by the oxidant gas supply means, discharge of fuel gas by the discharge means, and extraction of current by the current extraction means ,
The control means includes pressure control means for controlling the pressure of the fuel gas supplied to the fuel cell. When the system is started, supply of the oxidant by the oxidant supply means and discharge of the fuel gas by the discharge means When the fuel gas is supplied by the fuel gas supply means, the pressure of the fuel gas is increased to a target value, and the flow control means performs the start-up control for taking out the current by the current extraction means. A fuel cell system, wherein the amount of oxygen staying in the fuel electrode is estimated based on the behavior of the detected flow rate. 15. The fuel cell according to claim 14, wherein the amount of oxygen staying in the fuel electrode is estimated based on a time until the detected value detected by the flow rate detecting means falls below a predetermined flow rate. system. The fuel gas supply means includes a pressure regulating valve that adjusts the pressure of the fuel gas,
15. The amount of oxygen staying in the fuel electrode is estimated based on a time until the valve opening of the pressure regulating valve is reduced to a predetermined valve opening after the start control is started. The fuel cell system described. The fuel gas supply means includes a pressure regulating valve that adjusts the pressure of the fuel gas,
The amount of oxygen staying in the fuel electrode is estimated based on an integrated value of time until the valve opening of the pressure regulating valve is reduced to a predetermined valve opening after the start control is started. Item 17. The fuel cell system according to Item 16. The control means sets an end time for ending the start control based on the estimated oxygen amount.
The fuel cell system according to any one of claims 14 to 17, wherein In a fuel cell system including a fuel cell that generates power by an electrochemical reaction between a fuel gas supplied to the fuel electrode by the fuel gas supply means and an oxidant gas supplied to the oxidant electrode by the oxidant gas supply means,
Pressure detecting means for detecting the pressure of the fuel gas at the fuel electrode;
Flow rate detecting means for detecting the flow rate of the fuel gas supplied to the fuel cell;
Discharging means for discharging unused fuel gas supplied to the fuel cell to the outside of the fuel cell;
Current extraction means for extracting the current obtained by the fuel cell from the fuel cell;
Control means for controlling supply of fuel gas by the fuel gas supply means, supply of oxidant gas by the oxidant gas supply means, discharge of fuel gas by the discharge means, and extraction of current by the current extraction means ,
The control means includes flow rate control means for controlling the flow rate of the fuel gas supplied to the fuel cell, and supply of the oxidant by the oxidant supply means and discharge of the fuel gas by the discharge means when the system is started up. In the state where the fuel gas is supplied by the fuel gas supply means, the flow rate of the fuel gas is controlled to a target value by the flow rate control means, and the start control for taking out the current by the current extraction means is performed, A fuel cell system, wherein the amount of oxygen staying in the fuel electrode is estimated based on the behavior of pressure detected by a pressure detection means. The control means sets an end time for ending the start control based on the estimated oxygen amount.
The fuel cell system according to claim 19. When the integral value of the flow rate detected by the flow rate detection unit reaches a predetermined value, the control unit estimates that oxygen remaining in the fuel electrode has disappeared and ends the start-up control. The fuel cell system according to claim 19 or 20. Current detection means for detecting the current extracted by the current extraction means;
The control means calculates the consumption amount of the fuel gas consumed by taking out the current at the time of start-up based on the current value detected by the current detection means, and based on the obtained consumption amount of the fuel gas The fuel cell system according to any one of claims 1 to 21, wherein the estimated amount of oxygen is corrected.

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