JP2006079891A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize a flow rate of hydrogen supplied to cells on the startup of a system and to prevent degradation in the cell performance. <P>SOLUTION: Prior to startup power generation of a fuel cell system, a variable valve 104 is opened by a predetermined opening rate; a controller 110 estimates hydrogen concentrations at a fuel cell stack 101 and a hydrogen passage, on the basis of a pressure of hydrogen supplied to the fuel cell stack 101; the pressure is detected by a hydrogen pressure sensor 109 after the expiration of a predetermined time interval; the opening rate of the variable valve 104 is adjusted by the controller 110, on the basis of the hydrogen concentrations estimated above; and hydrogen is supplied to the fuel cell stack 101 at a preset desired hydrogen flowrate Q. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that consumes electric power generated by supplying only hydrogen to a fuel cell when the system is started up, and consumes oxygen at a cathode electrode.

  A fuel cell vehicle is equipped with a hydrogen storage device such as a compressed hydrogen cylinder, a liquid hydrogen tank, a hydrogen storage alloy, etc., or a hydrocarbon-based fuel such as methanol is reformed, and hydrogen supplied from the hydrogen storage device or The hydrogen obtained by reforming and the atmosphere containing oxygen are sent and reacted to the fuel cell to generate electricity, and the electric motor is operated by the electric energy extracted from the fuel cell, and the driving wheel is driven by this electric motor. It is a traveling vehicle.

  Thus, when starting a fuel cell that generates power by chemically reacting a reaction gas of hydrogen of fuel gas and air of oxidant gas, the fuel cell is supplied after hydrogen and oxygen are constantly sent to the fuel cell. Until the load is connected to the fuel cell, the fuel cell is in a no-load state. As a result, it is conventionally known that the cells of the fuel cell are exposed to a high potential, and the characteristics of the catalyst on the cathode electrode side are degraded.

Further, if a load is connected to the fuel cell simultaneously with the flow of hydrogen and oxygen, it is possible to prevent the fuel cell from being exposed to a high potential. On the other hand, the difference in the flow time of hydrogen in each cell causes a difference in the time taken for hydrogen to reach each cell, resulting in cells that have reached hydrogen and cells that have not yet reached. For this reason, when a load is connected to the fuel cell simultaneously with the flow of hydrogen and oxygen, corrosion of the anode electrode occurs in a cell where hydrogen has not yet reached.

With respect to such a problem, in the technique described in Patent Document 1 shown below, when a voltage generated by supplying hydrogen to the fuel cell exceeds an upper limit value, a load is connected to the fuel cell. Control is performed so that the fuel cell does not become a high potential in an unloaded state, and oxidant air is supplied when hydrogen reaches all the cells. Thereby, it is avoided that load current flows in a state where hydrogen does not reach the cells of the fuel cell, and corrosion of the fuel electrode is prevented. Further, since the load current flows simultaneously with the introduction of air into the fuel cell, it is avoided that the cathode electrode is exposed to a high potential in an unloaded state.
Japanese Patent Laid-Open No. 10-144334

  As described above, in the conventional fuel cell system described in Document 1, it is not considered that air is mixed into the anode electrode while the fuel cell is stopped.

  In general, a fuel cell mounted on a fuel cell vehicle has a purge valve installed at a hydrogen discharge port opened while the vehicle is stopped. For this reason, while the fuel cell is stopped, air enters the fuel cell via the purge valve in the open state, and hydrogen remaining in the anode electrode is gradually replaced with air.

  As a result, even when hydrogen is supplied to the fuel cell at the same constant pressure when starting the fuel cell, the flow rate of hydrogen flowing to the anode electrode depends on how much hydrogen in the anode electrode is replaced with air. Will make a difference. When the flow rate of hydrogen supplied to the anode electrode is larger than a predetermined value set in advance, the voltage of the fuel cell rises rapidly. For this reason, the load connected to the fuel cell has a problem that the electric power generated in the fuel cell cannot be consumed and the cell is exposed to a high potential and the battery performance deteriorates.

  On the other hand, when the flow rate of hydrogen supplied to the anode electrode is smaller than a specified value, it is difficult for hydrogen to reach each cell, and it may take time until hydrogen is supplied to each cell. For this reason, when supplying power generated by supplying only hydrogen when the fuel cell is started to a load connected to the fuel cell, the load connected to the fuel cell is disconnected from the fuel cell before hydrogen reaches all the cells. There was a risk of it. For this reason, there was a problem that the anode electrode corroded in the cell where hydrogen did not reach, and the battery performance deteriorated.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a fuel cell system that optimizes the flow rate of hydrogen introduced into a cell at the time of system startup and prevents deterioration of battery performance. It is to provide.

  In order to achieve the above object, means for solving the problems of the present invention include a fuel cell that generates power by reacting a fuel gas and an oxidant gas, and a supply amount of the fuel gas supplied to the fuel cell. A fuel cell system comprising: an adjustment valve that performs adjustment control based on an opening; and an exhaust unit that exhausts fuel gas supplied to the fuel cell to the outside of the fuel cell. Estimating means for estimating the concentration of the fuel gas in the battery and in the flow passage through which the fuel gas flows from the regulating valve to the exhaust means via the fuel cell, and based on the fuel gas concentration estimated by the estimating means Control means for controlling the regulating valve and controlling supply of fuel gas to the fuel cell at a predetermined flow rate set in advance.

  According to the present invention, the fuel gas concentration in the fuel cell and the fuel gas flow passage is estimated before power generation at the time of starting the system, and the fuel gas is supplied based on the estimated fuel gas concentration. The desired fuel gas can be supplied to the fuel cell. Thereby, a rapid voltage rise or the like in the fuel cell is avoided, and deterioration of the cell performance can be prevented.

  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. 1 includes a fuel cell stack 101, a compressor 102, a throttle 103, a variable valve 104, an ejector 105, a purge valve 106, a power extraction device 107, a circulation flow path 108, a hydrogen pressure sensor 109, and a controller. 110 is comprised.

  The fuel cell stack 101 performs power generation by chemically reacting air of the oxidant gas supplied to the cathode electrode 101a and hydrogen of the fuel gas supplied to the anode electrode 101b. It is taken out by the take-out device 107 and supplied to a load connected to the system.

  The compressor 102 is provided in a flow path on the air supply side of the fuel cell stack 101, compresses air, controls the flow rate of air supplied to the cathode electrode 101a of the fuel cell stack 101, and controls the flow rate of the air. This is supplied to the cathode electrode 101 a of the fuel cell stack 101.

  The throttle 103 is provided in a flow path on the air exhaust side of the fuel cell stack 101, controls the pressure of the air discharged from the fuel cell stack 101, and exhausts the pressure-controlled air to the outside.

The variable valve 104 is provided in a flow path on the hydrogen supply side of the fuel cell stack 101, and controls the flow of hydrogen by regulating the pressure of high-pressure hydrogen stored in a hydrogen tank (not shown). Controlled hydrogen is supplied to the anode 101 b of the fuel cell stack 101. The variable valve 104 functions as an adjustment valve that adjusts and controls the flow rate of hydrogen supplied to the fuel cell stack 101. The ejector 105 is provided between the variable valve 104 and the hydrogen inlet of the fuel cell stack 101, and is a fuel cell. In order to reuse the unused hydrogen discharged from the stack 101, the unused hydrogen is supplied to the hydrogen supply side of the fuel cell stack 101 via the circulation channel 108 that connects the hydrogen outlet of the fuel cell stack 101 and the ejector 105. Reflux the hydrogen.

  The purge valve 106 exhausts unused hydrogen discharged from the fuel cell stack 101 in the open state to the outside of the fuel cell stack 101, and circulates unused hydrogen discharged from the fuel cell stack 101 in the closed state. Guide to road 108.

  The power take-out device 107 takes out and manages the power obtained by the power generation of the fuel cell stack 101 from the fuel cell stack 101 based on a command given from the controller 110, and loads the taken-out power connected to the fuel cell system. To control the supply.

  The hydrogen pressure sensor 109 is provided between the ejector 105 and the hydrogen inlet of the fuel cell stack 101, detects the pressure of hydrogen supplied to the anode electrode 101b of the fuel cell stack 101, and supplies the detected hydrogen pressure to the controller 110. give.

  The controller 110 functions as a control center for controlling the operation of the system, and includes, for example, a microcomputer having 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. It is realized by. The controller 110 reads signals from each sensor (not shown) in this system including the hydrogen pressure sensor 109, and based on the various signals read and control logic (program) stored in advance, the compressor 102 and the throttle 103 In addition, a command is sent to each component of the system including the variable valve 104, the purge valve 106, and the power extraction device 107, which is necessary for operation / stop of the system including the hydrogen supply operation at the time of starting the system, which will be described below. Control and control all operations. Such a controller 110 is configured as shown in FIG.

  2, the controller 110 includes a hydrogen concentration calculation unit 201, a variable valve control unit 202, a target pressure calculation unit 203, a variable valve opening calculation unit 204, a target extraction power calculation unit 205, and a power extraction control unit 206. And functions as an estimation means for estimating the hydrogen concentration in the fuel cell stack 101 and the hydrogen flow path, and a control means for controlling the flow rate of hydrogen supplied to the fuel cell stack 101 by adjusting and controlling the opening of the variable valve 104. To do.

  When the controller 110 is instructed to start the fuel cell system, the hydrogen concentration calculation unit 201 gives the variable valve control unit 202 a predetermined opening As as the initial opening of the variable valve 104. The hydrogen concentration calculation unit 201 instructs the variable valve control unit 202 to set a predetermined opening As, and after the opening of the variable valve 104 is adjusted and controlled to the predetermined opening As, the hydrogen pressure detected by the hydrogen pressure sensor 109 is detected. Based on this hydrogen pressure, the hydrogen concentration in the anode electrode 101 b of the fuel cell stack 101 and the circulation channel 108 is calculated and estimated, and the obtained hydrogen concentration is given to the target pressure calculation unit 203.

  The variable valve control unit 202 inputs the predetermined opening As given from the hydrogen concentration calculation unit 201 and the target opening given from the variable valve opening calculation unit 204, and sets the predetermined opening As and the target opening. Based on this, the opening degree of the variable valve 104 is adjusted and controlled. In other words, the variable valve control unit 202 adjusts and controls the variable valve 104 to the predetermined opening As when the predetermined opening As is input, and then when the target opening is input, the variable valve 104 is opened to the target opening. Adjust control every time.

  The target pressure calculation unit 203 inputs the hydrogen concentration calculated by the hydrogen concentration calculation unit 201, and based on this hydrogen concentration, the fuel pressure is set so as not to deteriorate the fuel cell stack 101 when starting the fuel cell system. A target hydrogen pressure for realizing a hydrogen flow rate Q of hydrogen supplied to the battery stack 101 is calculated. Here, before oxidant air is supplied to the fuel cell stack 101 and power generation is started when the system is activated, only hydrogen is supplied to the anode electrode 101b without supplying the oxidant air to the cathode electrode 101a. At this time, the hydrogen flow rate Q that does not deteriorate the fuel cell stack 101 is determined in advance by experiments, desktop studies, or the like. The target pressure calculation unit 203 gives the target hydrogen pressure obtained by the calculation to the variable valve opening calculation unit 204.

  The variable valve opening calculation unit 204 receives the hydrogen pressure detected by the hydrogen pressure sensor 109 and the target hydrogen pressure calculated by the target pressure calculation unit 203, and detects based on the hydrogen pressure and the target hydrogen pressure. The target opening degree of the variable valve 104 for setting the hydrogen pressure thus obtained to the target hydrogen pressure is calculated. The variable valve opening calculation unit 204 gives the target opening obtained by the calculation to the variable valve control unit 202.

  The target extraction power calculation unit 205 calculates the power extracted from the fuel cell stack 101, and the target extraction power obtained by the calculation is given to the power extraction control unit 206.

  The power take-out control unit 206 receives the target take-out power given from the target take-out power calculation unit 205 and gives a command to the power take-out device 107 to take out the target take-out power from the fuel cell stack 101.

  Although not shown in FIG. 2, the controller 110 includes a purge valve control unit that controls opening and closing of the purge valve 106, a compressor control unit that controls the operation of the compressor 102, and throttle control that controls the operation of the throttle 103. Department. Prior to power generation at the start-up of this system, the purge valve control unit gives a valve opening command to the purge valve 106 to open the purge valve, and the compressor control unit gives a stop command to the compressor 102 to stop the compressor 102 Then, the throttle control unit gives a stop command to the throttle 103 to stop the throttle 103.

  The controller 110 controls the system so that the amount of hydrogen supplied to the fuel cell stack 101 before the power generation at the time of starting the system is the hydrogen flow rate Q according to the procedure of the flowchart shown in FIG. 3 is performed every predetermined cycle, for example, every 10 [msec].

  In FIG. 3, when the system is started, first, the purge valve 106 is opened, the compressor 102 and the throttle 103 are stopped, and the variable valve 104 is opened to a predetermined opening As based on a command from the controller 110. Then, without supplying air to the cathode 101a of the fuel cell stack 101, hydrogen is supplied to the anode 101b of the fuel cell stack 101 via the variable valve 104 having a predetermined opening degree As (step S301). A method for determining the predetermined opening As of the variable valve 104 will be described later.

  Subsequently, the hydrogen pressure Ph detected by the hydrogen pressure sensor 109 is read into the controller 110 (step S302). Thereafter, it is determined whether or not a predetermined time Tth has elapsed since the start of the system (step S303). As a result of the determination, if the time from the start of activation has not elapsed the predetermined time Tth, the processing routine is terminated, while if it has elapsed, the hydrogen concentration is calculated (step S304). A method for determining the predetermined time Tth will be described later.

  The hydrogen concentration is determined in advance by experiments, desk studies, etc., and the hydrogen pressure when the predetermined time Tth elapses after the opening of the variable valve 104 is set to the predetermined opening As and hydrogen is supplied to the fuel cell stack 101. Based on the hydrogen concentration and the characteristics as shown in FIG. 4, the hydrogen concentration calculation unit 201 calculates the hydrogen pressure Ph detected in step S <b> 302. When the calculation of the hydrogen concentration is completed, the target pressure calculation unit 203 performs hydrogenation based on the characteristics as shown in FIG. 5 of the hydrogen concentration and the hydrogen pressure for realizing the hydrogen flow rate Q, which are obtained through experiments and desk studies. A target hydrogen pressure corresponding to the hydrogen concentration obtained by the calculation of the concentration calculation unit 201 is calculated. When the calculation of the target hydrogen pressure is completed, detection is performed based on a map, table, or calculation expression indicating the relationship between the opening of the variable valve and the hydrogen pressure so that the hydrogen pressure Ph detected in step S302 is set to the target hydrogen pressure. The target opening of the variable valve 104 is calculated by the variable valve opening calculator 204 using the hydrogen pressure Ph and the target hydrogen pressure (step S305).

  Subsequently, the target opening of the variable valve 104 obtained by the calculation is given to the variable valve control unit 202, and the variable valve control unit 202 instructs the variable valve 104 so that the opening of the variable valve 104 becomes the target opening. To adjust the opening and control, and the series of processing routines is completed.

  Next, how to determine the predetermined opening As of the variable valve 104 and the predetermined time Tth for supplying hydrogen through the variable valve 104 having the predetermined opening As will be described.

  FIG. 6 is a diagram showing a change in the hydrogen pressure Ph when the fuel cell system is in a stopped state and the variable valve 104 is opened to a predetermined opening As and hydrogen is supplied. In FIG. 6, when the anode 101 b of the fuel cell stack 101 and the circulation channel 108 (hereinafter collectively referred to as a hydrogen channel) are filled with air, the hydrogen pressure increases with time. When the hydrogen flow path is filled with hydrogen, the characteristics change as shown in (2) of FIG.

  The hydrogen flowing in from the variable valve 104 having the predetermined opening degree As pushes out the gas filling the hydrogen flow path, passes through the fuel cell stack 101, and is discharged from the purge valve 106 in the open state. The exhausted gas has a pressure loss according to the throttle (opening) of the purge valve 106, and the pressure of the hydrogen flow path, that is, the hydrogen pressure Ph increases. At this time, as the ratio of the gas filling the hydrogen flow path containing air heavier than hydrogen increases, the rate of increase in hydrogen pressure increases as shown in FIG. There is a characteristic that the increase rate of hydrogen pressure becomes smaller as the amount increases.

  The present invention uses such characteristics to obtain the relationship between the hydrogen pressure and the hydrogen concentration as shown in FIG. 4 at the predetermined time Tth in FIG. 6, calculates the hydrogen concentration in the hydrogen flow path, and calculates the hydrogen concentration from the hydrogen concentration. A target hydrogen pressure for supplying a desired hydrogen flow rate Q to the fuel cell stack 101 is obtained. As described above, the hydrogen flow rate is obtained in consideration of the ratio of hydrogen to air in the hydrogen flow path, so that a desired hydrogen flow rate Q that does not cause deterioration of the fuel cell stack 101 is reliably supplied to the fuel cell stack 101. It becomes possible to do.

  As described above, the predetermined opening degree As of the variable valve 104 is sufficient to generate a pressure increase difference that can be determined as to how much of the gas fills the hydrogen flow path, as shown in FIG. Set the opening as small as possible. On the other hand, as the predetermined time Tth is longer, the calculation accuracy of the hydrogen concentration can be increased. However, if the predetermined time Tth is too long, hydrogen reaches the electrolyte membrane of the anode 101b. Therefore, when the variable valve 104 is opened to the predetermined opening As, the maximum time Tmax until hydrogen reaches the electrolyte membrane of the anode electrode 101b is obtained in advance through experiments, desk studies, etc., and is within the maximum time Tmax. Is set to a predetermined time Tth.

  In the first embodiment, the hydrogen concentration is calculated using the hydrogen pressure Ph detected by the hydrogen pressure sensor 109 after the predetermined time Tth has elapsed. The differential value of the hydrogen pressure Ph is obtained, and the hydrogen concentration is calculated using this differential value. May be calculated.

  As described above, in the first embodiment, the hydrogen concentration in the anode electrode 101b of the fuel cell stack 101 and the hydrogen flow path of the circulation flow path 108 is estimated, and the fuel cell stack 101 is supplied based on the estimated hydrogen concentration. Therefore, when the system is started up, only hydrogen is supplied and the generated electric power is consumed by the load to consume the oxygen in the cathode 101a. It becomes possible to supply with high accuracy. As a result, the voltage of the fuel cell stack 101 suddenly rises and cannot be consumed by the load connected to the system, and the cell becomes high potential, or conversely, the load is disconnected from the system before hydrogen reaches all the cells. This can be avoided and deterioration of battery performance can be prevented.

  In addition, the actuators and sensors used to estimate the hydrogen concentration in the hydrogen flow path are all necessary for system operation control, so a special device for estimating the hydrogen concentration is additionally provided. It can be realized without doing. Thereby, the enlargement of a structure and complication can be avoided.

  Furthermore, the hydrogen supplied before power generation is necessary for power generation as it is, and the hydrogen concentration can be estimated without wasting unnecessary energy.

  Next, a second embodiment of the present invention will be described. The feature of the second embodiment is that, compared to the first first embodiment, after the variable valve 104 is opened to a predetermined opening As and hydrogen is supplied to the fuel cell stack 101, the hydrogen pressure is predetermined. The hydrogen concentration is calculated and estimated when the pressure becomes higher than the pressure, and the others are the same as in the first embodiment. Therefore, the system configuration of the second embodiment is the same as that of FIG. 1, and the processing procedure of the controller 110 is as shown in the flowchart of FIG. 7, compared with the processing procedure of the first embodiment shown in FIG. Steps S703 and S704 are executed instead of steps S303 and S304.

  In FIG. 7, after performing the processing of steps S301 and S302 shown in FIG. 3, it is determined whether or not the hydrogen pressure Ph detected by the hydrogen pressure sensor 109 exceeds a predetermined hydrogen pressure Pth (see FIG. 7). Step S703). As a result of the discrimination, if the hydrogen pressure Ph does not exceed the hydrogen pressure Pth, the process is terminated, while if it exceeds, the hydrogen concentration is calculated (step S704). The predetermined hydrogen pressure Pth is a value that can be exceeded even when the hydrogen flow path is filled with hydrogen, as shown in (2) of FIG. 6, and that can be exceeded within the maximum time Tmax described above. Set.

  The hydrogen concentration is obtained in advance by experiments, desk studies, and the like, and the opening time of the variable valve 104 is set to a predetermined opening As and hydrogen is supplied to the fuel cell stack 101 in FIG. Based on the characteristics shown, the hydrogen concentration calculation unit 201 calculates using a preset elapsed time Tc after the variable valve 104 is opened to the predetermined opening As. The subsequent steps are the same as in the first embodiment.

  Also in the second embodiment, the same effect as in the first embodiment can be obtained.

  Next, Embodiment 3 of the present invention will be described. A feature of the third embodiment is that the hydrogen pressure Ph of hydrogen supplied before power generation at the time of system startup converges within a predetermined target hydrogen pressure Ps ± control error Per when the variable valve 104 is converged. The hydrogen concentration is calculated based on the opening degree. The basic configuration of the system is the same as that of the first embodiment, but the controller 110 is configured as shown in FIG.

  In FIG. 9, the controller 110 includes a hydrogen concentration calculation unit 901, a variable valve control unit 902, a target pressure calculation unit 903, a variable valve opening calculation unit 904, and the same target extraction as that shown in FIG. The power calculation unit 205 and the power extraction control unit 206 are provided. Further, the controller 110 includes a purge valve control unit, a compressor control unit, and a throttle control unit, which are not shown, but are the same as those in the first embodiment.

  When the controller 110 is instructed to start the fuel cell system, the hydrogen concentration calculator 901 instructs the variable valve opening calculator 904 to set a predetermined target hydrogen pressure Ps. The hydrogen concentration calculation unit 901 inputs the hydrogen pressure detected by the hydrogen pressure sensor 109 and the target opening of the variable valve 104 calculated by the variable valve opening calculation unit 904, and the hydrogen pressure is a predetermined target hydrogen pressure. When Ps is reached, the hydrogen concentration in the hydrogen flow path between the anode 101b and the circulation flow path 108 is calculated and estimated based on the target opening of the variable valve 104 at that time. The obtained hydrogen concentration is given to the target pressure calculation unit 903.

  The variable valve control unit 902 inputs the target opening of the variable valve 104 calculated by the variable valve opening calculation unit 904, and performs adjustment control so that the opening of the variable valve 104 becomes the target opening.

  The target pressure calculation unit 903 receives the hydrogen concentration calculated by the hydrogen concentration calculation unit 901, and calculates the target hydrogen pressure that achieves the same hydrogen flow rate Q as in the first embodiment as in the first embodiment. Then, the calculated target hydrogen pressure is given to the variable valve opening calculation unit 904.

  The variable valve opening calculation unit 904 includes a hydrogen pressure detected by the hydrogen pressure sensor 109, a predetermined target hydrogen pressure Ps given from the hydrogen concentration calculation unit 901, and a target hydrogen pressure calculated by the target pressure calculation unit 903. First, the target opening of the variable valve 104 at which the hydrogen pressure becomes the predetermined target hydrogen pressure Ps is calculated by the same method as in the first embodiment, and the calculated target opening is calculated using the variable valve control unit 902 and the hydrogen concentration. This is given to the calculation unit 901. The variable valve opening calculation unit 904 is a variable valve in which the hydrogen pressure becomes the target hydrogen pressure when the target hydrogen pressure is given from the target pressure calculation unit 903 after the hydrogen concentration is calculated by the hydrogen concentration calculation unit 901. The target opening of 104 is calculated, and the calculated target opening is given to the variable valve control unit 902 and the hydrogen concentration calculation unit 901.

  The controller 110 controls the system so that the supply amount of hydrogen supplied to the fuel cell stack 101 before the power generation at the start of the system is the hydrogen flow rate Q according to the procedure of the flowchart shown in FIG. Note that the processing shown in FIG. 10 is performed every predetermined period, for example, every 10 [msec].

  In FIG. 10, when the system is started, first, based on a command from the controller 110, the purge valve 106 is opened, the compressor 102 and the throttle 103 are stopped, the variable valve 104 is opened, and the fuel cell stack is opened. Air is not supplied to the cathode electrode 101a of 101, but hydrogen is supplied to the anode electrode 101b of the fuel cell stack 101 via the variable valve 104 (step S1001).

  Thereafter, the hydrogen pressure Ph detected by the hydrogen pressure sensor 109 is read into the controller 110 (step S1002). Subsequently, the target opening of the variable valve 104 at which the detected hydrogen pressure Ph becomes the predetermined target hydrogen pressure Ps is calculated by the variable valve opening calculator 904 (step S1003).

  The predetermined target hydrogen pressure Ps is determined when the hydrogen flow path between the anode 101b and the circulation flow path 108 is filled with air or the hydrogen is filled with hydrogen in consideration of the allowable opening range of the variable valve 104. Even if it exists, it is set to a pressure that can be realized and that hydrogen does not reach the electrolyte membrane of the anode 101b before the calculation of the hydrogen concentration is completed.

  Next, after the variable valve 104 is adjusted and controlled to the target opening, it is determined whether or not the hydrogen pressure Ph is within a predetermined target hydrogen pressure Ps ± control error Per (step S1004). If the determination result shows that the hydrogen pressure Ph is not within the range, the processing routine is terminated. If the hydrogen pressure Ph is within the range, the hydrogen concentration calculation unit 901 calculates the hydrogen concentration (step S1005).

  Note that the control error Per is set in advance as a value by which it can be determined that the hydrogen pressure has sufficiently converged to the target value through experiments, desk studies, or the like.

  The hydrogen concentration is calculated by the variable valve opening calculation unit 904 based on the characteristics shown in FIG. 11 of the opening of the variable valve 104 and the hydrogen concentration at the hydrogen pressure Ph, which are obtained in advance through experiments, desk studies, and the like. Calculation is performed using the opening degree of the variable valve 104 thus made. When the calculation of the hydrogen concentration is completed, the subsequent processing procedure is the same as in the first embodiment, and the target opening of the variable valve 104 is calculated based on the calculated hydrogen concentration, and the desired hydrogen flow rate Q is set to the fuel cell. It is supplied to the anode 101 b of the stack 101.

  In the third embodiment, the hydrogen concentration is calculated using the opening of the variable valve 104 when the hydrogen pressure Ph is within the range of the predetermined target hydrogen pressure Ps ± control error Per. An integrated value of the opening degree of the variable valve 104 after the start may be obtained, and the hydrogen concentration may be calculated based on this integrated value. Alternatively, the time until the hydrogen pressure Ph falls within the range of the predetermined target hydrogen pressure Ps ± control error Per may be measured, and the hydrogen concentration may be calculated using the measured time.

  As described above, also in the third embodiment, the same effect as in the first embodiment can be obtained, and hydrogen can be supplied at the maximum pressure that the fuel cell stack 101 can tolerate. The process of calculating and estimating the hydrogen concentration in a shorter time than in Example 1 and Example 2 can be completed.

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 controller shown in FIG. 3 is a flowchart illustrating an operation procedure at the time of start-up according to the first embodiment. It is a figure which shows the relationship between the hydrogen pressure in Example 1, and a hydrogen concentration. It is a figure which shows the relationship between the hydrogen pressure and hydrogen concentration for implement | achieving the desired hydrogen flow volume Q in Example 1. FIG. It is a figure which shows the time change of the hydrogen pressure with respect to the hydrogen concentration of a hydrogen flow path in the stop state of a system. 10 is a flowchart illustrating an operation procedure at the time of start-up according to the second embodiment. It is a figure which shows the time change of the hydrogen concentration with respect to the opening degree of the variable valve in Example 2, and a hydrogen pressure. FIG. 10 is a diagram illustrating a configuration of a controller according to a third embodiment. 10 is a flowchart illustrating an operation procedure at the time of startup according to a third embodiment. It is a figure which shows the relationship between the opening degree of the variable valve with respect to hydrogen pressure, and hydrogen concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Fuel cell stack 101a ... Cathode pole 101b ... Anode pole 102 ... Compressor 103 ... Throttle 104 ... Variable valve 105 ... Ejector 106 ... Purge valve 107 ... Power extraction device 108 ... Circulation flow path 109 ... Hydrogen pressure sensor 110 ... Controller 201, 901 ... Hydrogen concentration calculation unit 202, 902 ... Variable valve control unit 203, 903 ... Target pressure calculation unit 204, 904 ... Variable valve opening calculation unit 205 ... Target extraction power calculation unit 206 ... Power extraction control unit

Claims (7)

A fuel cell that generates electricity by reacting a fuel gas and an oxidant gas; and
An adjustment valve for adjusting and controlling the amount of fuel gas supplied to the fuel cell based on the valve opening;
A fuel cell system comprising exhaust means for exhausting the fuel gas supplied to the fuel cell to the outside of the fuel cell;
Estimating means for estimating the concentration of the fuel gas in the fuel cell and in the flow path through which the fuel gas flows from the regulating valve to the exhaust means through the fuel cell at the time of starting the fuel cell system;
Control means for controlling the regulating valve based on the concentration of the fuel gas estimated by the estimating means and controlling the supply of the fuel gas to the fuel cell at a preset desired flow rate. Fuel cell system. Pressure detecting means provided in the flow passage for detecting the pressure of the fuel gas supplied to the fuel cell;
2. The fuel cell system according to claim 1, wherein the estimating means estimates the concentration of the fuel gas based on the opening of the regulating valve and the pressure of the fuel gas detected by the pressure detecting means. The estimation means detects the concentration of the fuel gas based on the pressure of the fuel gas detected by the detection means after the adjustment valve is opened at a predetermined opening degree and a predetermined time has elapsed. The fuel cell system according to claim 2. Pressure detecting means provided in the flow passage for detecting the pressure of the fuel gas supplied to the fuel cell;
The estimation means is a time until the pressure of the fuel gas detected by the detection means reaches a preset predetermined value or more after a predetermined time has elapsed after opening the regulating valve at a preset predetermined opening. 2. The fuel cell system according to claim 1, wherein the concentration of the fuel gas is detected based on the above. Adjusting the opening of the adjusting valve to control the pressure of the fuel gas detected by the detecting means to a predetermined pressure set in advance;
The said estimation means detects the density | concentration of fuel gas based on the opening degree of the said adjustment valve when the pressure of fuel gas detected by the said detection means converges to predetermined pressure, The fuel gas density | concentration is detected. Fuel cell system. Pressure detecting means provided in the flow passage for detecting the pressure of the fuel gas supplied to the fuel cell;
Adjusting the opening of the adjusting valve to control the pressure of the fuel gas detected by the detecting means to a predetermined pressure set in advance;
2. The fuel cell system according to claim 1, wherein the estimating means detects the concentration of the fuel gas based on the time taken by the detecting means until the pressure of the fuel gas converges to a predetermined pressure. The said estimation means estimates the density | concentration of fuel gas before oxidant gas is supplied to the said fuel cell at the time of starting of a fuel cell system, The fuel cell system is characterized by the above-mentioned. The fuel cell system according to any one of the above.

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