JP2004303444A - Back pressure controller of solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply a feed forward (FF) control to a flow-rate valve using a computing equation which regards a plurality of physical quantities related to the back pressure as variables, to control the back pressure of a fuel cell. <P>SOLUTION: A back pressure controller comprises large- and small-flow-rate valves 8, 9 connected to the fuel cell 1 in parallel, a back pressure sensor 15, and first and second control means 21, 22. The first control means 21 has the computing equation which regards the plurality of physical quantities related to the back pressure as variables, and gives a FF control signal to the large-flow-rate valve 9 from the computing result based on the operating condition of the fuel cell and the computing equation. The second control means 22 gives a FB control signal to the small-flow-rate valve 8 based on the detecting result of the back pressure sensor. The FF control of the first control means controls a basic part of the control range, and the FB control of the second control means controls the fine adjustment part. Since the ratio depending on the FB control is low, even if hunting occurs by increasing the sensitivity of a PID constant, its influence is little. Since the basic part is controlled by the FF control based on the quick computing by the computing equation with multivariables whose basic parts are determined in advance, the response time is reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is provided in a polymer electrolyte fuel cell using a polymer electrolyte membrane between a fuel electrode and an air electrode as an electrolyte, and is formed by unreacted fuel and air discharged from the polymer electrolyte fuel cell. The present invention relates to a back pressure control device for controlling pressure.
[0002]
[Prior art]
A fuel cell is a power generation device that converts a chemical energy of a fuel into an electric energy by electrochemically reacting a fuel such as hydrogen with an oxidant such as air. Among these types of fuel cells, a solid polymer type fuel cell using a polymer ion exchange membrane for the electrolyte has a high output density, a low operating temperature of about 70 ° C. to 90 ° C., a simple structure, and a simple electrolyte. It has the features that the entire fuel cell including the fuel cell can be made of a solid, and that the polymer membrane is resistant to a differential pressure. A high output density means that a large and compact output can be obtained, and a low-temperature operation means that handling at the time of startup and the like is easy. It can be used in various fields such as automobiles, homes, and portables.
[0003]
By the way, in the polymer electrolyte fuel cell, the control of the back pressure by the unreacted fuel and the air discharged is an important problem. Typically, a valve is provided. Thereby, the pressure on the anode side with respect to the cathode side of the polymer electrolyte fuel cell is set to a predetermined pressure to secure a predetermined power generation efficiency, and the flow rate of fuel supplied to the polymer electrolyte fuel cell is controlled. , A predetermined output can be obtained.
Prior art document information related to the invention of the polymer electrolyte fuel cell having such a back pressure control valve is as follows.
[0004]
[Patent Document 1]
JP 2001-338671 A [0005]
In the control device for a fuel cell according to Patent Document 1, two valves, a small flow valve and a large flow valve, for controlling the fuel discharged from the fuel cell are arranged and connected in parallel. The control unit closes the large flow valve in the low flow rate range, feedback-controls the small flow rate valve based on the operating pressure and the flow rate of the off gas, and feed-forward controls the large flow rate valve based on the operating pressure and the flow rate of the off gas in the high flow rate range. In addition, the small flow valve is similarly feedback-controlled to improve accuracy.
[0006]
[Problems to be solved by the invention]
However, in the fuel cell control device according to Patent Document 1 described above, the back pressure is not suitably controlled, and in fact, the pressure on the anode side with respect to the cathode side of the fuel cell cannot be maintained at a good value, There was a problem that stable back pressure could not be secured.
[0007]
The present inventors analyzed the cause as follows. That is, in Patent Literature 1, both the feedforward control of the large flow valve and the feedback control of the small flow valve are performed by a map (table) method that searches the opening degree of the valve from two variables. That is, the valve opening is uniquely determined by the operating pressure and the flow rate of the off-gas. However, the back pressure of the fuel cell, which must be adjusted by controlling the opening of the valve, cannot actually be determined solely by the operating pressure and the flow rate of off-gas, but also correlates with other physical quantities that indicate the operating state of the fuel cell. It is considered that if these other physical quantities change, the back pressure also changes.
[0008]
Therefore, the present invention has been made based on the above findings found by the inventors of the present application, and in order to control the back pressure of unreacted fuel and air in a polymer electrolyte fuel cell, it is not a simple map method. It is an object of the present invention to provide a back pressure control device which gives a control signal to a flow rate control means (back pressure valve) by performing a calculation with a predetermined calculation formula using a plurality of types of physical quantities correlated with the back pressure. And
[0009]
[Means for Solving the Problems]
The back pressure control device for a polymer electrolyte fuel cell according to claim 1, wherein the unreacted gas discharged from the polymer electrolyte fuel cell using the polymer electrolyte membrane as an electrolyte between the fuel electrode and the air electrode. Back pressure control device for polymer electrolyte fuel cell that controls back pressure by fuel and air,
Flow rate control means connected to an outlet of the polymer electrolyte fuel cell from which unreacted fuel and air are discharged,
A back pressure sensor for detecting the back pressure;
The operational condition of the polymer electrolyte fuel cell has an arithmetic expression of the back pressure, which indicates an operating state of the polymer electrolyte fuel cell and has a plurality of types of physical quantities correlated with the back pressure as variables. And a first control means for performing a calculation based on the calculation formula, and providing a feedforward control signal to the flow control means based on the calculation result;
It is characterized by having.
[0010]
The back pressure control device for a polymer electrolyte fuel cell according to claim 2 is the back pressure control device for a polymer electrolyte fuel cell according to claim 1,
When the other physical quantities other than the plurality of physical quantities become disturbances to the control based on the arithmetic formula, the function of creating a new arithmetic formula in which the other physical quantities are added as variables is used in the first control. It is characterized by having the means.
[0011]
The back pressure control device for a polymer electrolyte fuel cell according to claim 3 is the back pressure control device for a polymer electrolyte fuel cell according to claim 1,
When the control based on the arithmetic expression is suitably performed, the first control means has a function of creating a new arithmetic expression by recalculating the arithmetic expression based on the control result. And
[0012]
The back pressure control device for a polymer electrolyte fuel cell according to claim 4 is the back pressure control device for a polymer electrolyte fuel cell according to claim 1, 2 or 3,
A second control unit that provides a feedback control signal to the flow control unit based on a detection result of the back pressure sensor,
The control range of the back pressure is divided into a basic part that is feed-forward controlled by the first control means and a fine adjustment part that is feedback-controlled by the second control means,
After the control of the basic part is achieved by the feedforward control of the first control means, the control of the fine adjustment part is achieved by the feedback control of the second control means.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a back pressure control device for a polymer electrolyte fuel cell according to the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is a diagram showing an embodiment of a back pressure control device for a polymer electrolyte fuel cell according to the present invention, and FIG. 2 is an explanatory diagram schematically showing the contents and functions of control in the back pressure control device.
[0015]
(1) Configuration of Polymer Electrolyte Fuel Cell In FIG. 1, a polymer electrolyte fuel cell 1 (hereinafter, also simply referred to as a fuel cell 1) according to the present embodiment has a solid polymer ion exchange membrane or the like. A cell formed by sandwiching a molecular electrolyte membrane between an anode and a cathode from both sides is used as a structural unit, and is constituted by a stack formed by stacking a plurality of cells, and a hydrogen electrode to which, for example, hydrogen is supplied as a fuel, And an air electrode to which air containing, for example, oxygen is supplied as an agent. The air electrode and the fuel electrode are provided with outlets 1a for discharging unreacted fuel and oxidizer out of the supplied fuel and oxidizer, and each outlet 1a has an air outlet. The pipe which is opened to is connected.
[0016]
(2) Configuration of Control Device In FIG. 1, the control device 2 of the fuel cell 1 according to the present embodiment supplies a fuel supply unit 3 for supplying fuel to the fuel cell 1 and an oxidant such as air to the fuel cell 1. An oxidant supply unit 4, a flow control unit 5 connected to an outlet 1a of the fuel cell 1 from which unreacted fuel and air are discharged, and a DC which is generated by the fuel cell 1 is converted into an AC to load. And a control unit 7.
[0017]
(1) Fuel supply unit 3
First, the fuel supply unit 3 is a unit for supplying a liquid fuel composed of, for example, a mixed solution of methanol and water. Although not shown, a vapor generation unit that evaporates the liquid fuel to generate fuel vapor, a vapor generation unit A combustion unit that generates combustion gas used for evaporating warm air and liquid fuel, a reforming unit that generates hydrogen-rich reformed fuel from fuel vapor, and selectively oxidizes carbon monoxide in the reformed fuel. It also includes a CO reduction unit to be removed and an auxiliary fuel supply unit.
[0018]
The fuel supply unit 3 vapor-generates a liquid fuel such as a mixed liquid obtained by mixing a fuel composed of an alcohol-based compound such as methanol or a hydrocarbon-based compound such as methane, ethane or gasoline with water at a predetermined ratio. Supply to the department. The steam generating section includes, for example, a nozzle or the like for supplying liquid fuel to the inside, and the liquid fuel sprayed from the nozzle is evaporated by the heat of the combustion gas supplied from the combustion section.
[0019]
The combustion unit includes, for example, a nozzle for introducing discharged fuel containing unreacted hydrogen discharged from the fuel electrode of the fuel cell 1 and discharged oxidant containing unreacted oxygen discharged from the air electrode; And a combustion catalyst for maintaining the combustion state of the exhaust oxidant, and an ignition source, for example, an electric heater. Then, the combustion gas generated by the combustion of the exhaust fuel and the exhaust oxidant is supplied to the steam generator. Further, the combustion section is provided with an auxiliary fuel supply section. By burning auxiliary fuel supplied from the auxiliary fuel supply section, the combustion section is warmed up, and the vapor generation section evaporates the liquid fuel. Generates combustion gas used for
[0020]
The reforming unit includes, for example, a reforming catalyst, and the reforming catalyst generates a reformed fuel having an increased hydrogen content (hydrogen-rich) from fuel vapor. For example, in the case of fuel vapor composed of a mixture of methanol and water, a reformed fuel containing hydrogen, water, and carbon monoxide is generated by the following reaction formulas (1) to (3).
CH3OH + 2O2 → 2H2O + CO2 (2)
CH3OH → 2H2 + CO (3)
Reaction equation (1) is a reforming reaction using methanol and water, and hydrogen as fuel is generated. The reaction formula (2) is an oxidation reaction of methanol, and replenishes the amount of heat required in the reaction formula (1), which is an endothermic reaction. The reaction formula (3) is a decomposition reaction of methanol inevitably generated, and carbon monoxide is generated. This carbon monoxide is removed by the CO reduction unit in order to poison a Pt catalyst or the like contained in the fuel cell 1 to lower the power generation efficiency and shorten the life of the fuel cell 1.
[0021]
The CO reduction unit includes a selective oxidation catalyst made of, for example, Pt or Ru, and selectively oxidizes and removes carbon monoxide contained in the reformed fuel by the following reaction formula (4).
2CO2 + O2 → 2CO2 ... (4)
Then, the reformed fuel having a reduced content of carbon monoxide is supplied to the fuel electrode of the fuel cell 1.
[0022]
(2) Oxidant supply unit 4
Next, the oxidizing agent supply unit 4 is provided with, for example, an air compressor (not shown), and pressurizes air or the like containing oxygen as an oxidizing agent based on a control signal from the control unit 7 so that the air of the fuel cell 1 is compressed. Supply to the pole. Then, in the fuel cell 1, the hydrogen (fuel) and the oxidant (oxygen) in the reformed fuel cause an electrochemical reaction to generate power.
[0023]
(3) Flow control means 5
Next, the flow control means 5 is connected to the outlet 1a of the polymer electrolyte fuel cell 1 from which unreacted fuel and air are discharged, and in this example, the small flow valve 8 and the large flow It is constituted by a valve 9. These valves are solenoid valves, and their opening degree is controlled by a control signal from the control unit 7, thereby controlling the pressure of unreacted fuel gas and air discharged from the fuel cell 1, that is, the back pressure of the fuel cell 1. can do.
[0024]
The two valves 8 and 9 are driven by, for example, a stepping motor or the like to adjust the valve opening in steps of a predetermined opening. For example, the valve opening per one step of the large flow valve 9 is a small flow valve. 8 is set to be smaller than the maximum valve opening. The coarse adjustment pressure flow control valve having a large valve opening per step (that is, the large flow valve 9) is feedforward controlled, and the fine adjustment pressure flow control valve having a small valve opening per step (that is, a small flow valve). 8) performs feedback control such as PID control. Here, in the low flow rate region of the discharged fuel, the large flow valve 9 is fully closed, and the pressure flow characteristic is changed only by the small flow valve 8. On the other hand, in the high flow rate region of the discharged fuel, the pressure flow characteristic is relatively largely changed by the feedforward control of the large flow valve 9, and the large change by the large flow valve 9 is corrected so as to correct the small flow valve. 8 is feedback controlled. In the present example, one large flow valve 9 is provided, but if two or more large flow valves 9 are provided in parallel, it is possible to cope with a further large flow rate.
[0025]
{Circle around (4)} Various detectors Next, a flow rate detector 10 is provided in the middle of the pipe connecting the fuel supply unit 3 and the fuel cell 1, and can measure the flow rate Q of the fuel. The fuel cell 1 is provided with a first pressure detector 11, which can measure the operating pressure P1 of the fuel cell 1. The fuel cell 1 is provided with a temperature detector 12 so that the operating temperature T of the fuel cell 1 can be measured. A current detector 14 is provided between the DC / AC converter 6 and the load 13 so that the load current I can be measured. Further, a second pressure detector 15 (back pressure sensor) is provided in the middle of the pipe connecting the fuel cell 1 and the flow control means 5, and the back pressure of the fuel cell 1 can be measured.
[0026]
(5) Control unit 7
Next, the control unit 7 controls the flow rate of the discharged fuel in the discharged fuel flow rate control unit 7 in response to a power generation request based on, for example, the operation of an accelerator pedal in a vehicle such as an electric vehicle. For this reason, the control unit 7 receives the pressure signal of the fuel supplied from the CO reduction unit to the fuel cell 1 and the signal from the flow rate detector 10 for detecting the flow rate Q of the reformed fuel supplied to the fuel cell 1. The signal from the second pressure detector 15 for detecting the pressure P2 of the discharged fuel discharged from the fuel cell 1, the signal for detecting the power generation current generated in the fuel cell 1, and the signal of the target power generation amount Is entered. Then, for example, the fuel injection command value is output from the control unit 7 to the fuel supply unit 3, and the generated current command value is output to the DC / AC converter 6 and used for output control for the load 13.
[0027]
The control unit 7 has a first control unit 21 and a second control unit 22 for controlling the flow control unit 5.
The first control means 21 has an arithmetic expression of the back pressure, which indicates an operating state of the polymer electrolyte fuel cell 1 and has a plurality of kinds of physical quantities correlated with the back pressure as variables. An arithmetic operation is performed based on the operating conditions of the polymer electrolyte fuel cell 1 and the arithmetic expression, and a feedforward control signal can be given to the large flow valve 9 of the flow control means 5 based on the arithmetic result. .
[0028]
In this example, the plurality of types of physical quantities correlated with the back pressure are the fuel flow rate Q, the fuel pressure P1, the load current I, the operating temperature T of the fuel cell 1, and the density D of the fuel used. . The operating conditions such as the density D of the fuel to be used and the target power generation amount are input to the control unit 7 as necessary.
[0029]
The above arithmetic expressions using these physical quantities as variables can be performed by manually operating the entire apparatus or performing a plurality of actual operations by PID control using each signal alone while taking signals from the respective detectors. Calculates a correlation coefficient between the back pressure to be controlled and each physical property amount from, and thereby creates a back pressure. Once this arithmetic expression is obtained, the signals from the detectors provided in the various parts of the apparatus are not necessarily required thereafter, and the given operational condition is used to apply the arithmetic expression to the large flow valve 9 of the flow rate control means 5. The feedforward control signal to be given can be immediately calculated and used for control.
[0030]
The greater the number of actual operations to obtain the correlation coefficient, the greater the number of types of physical quantities that are variables of the arithmetic expression having a correlation with the back pressure. The more the expression becomes, the closer to the one that can perform ideal feedforward control. However, in practice, a useful arithmetic expression can be created with a population of about 10 data.
[0031]
Further, when the other physical quantity other than the plurality of physical quantities becomes a disturbance to the control based on the arithmetic expression, the first control means 21 adds a new physical quantity as a variable. It has software with the function of creating arithmetic expressions.
[0032]
Further, the first control means 21 is a software having a function of creating a new arithmetic expression by recalculating the arithmetic expression based on the control result when the control based on the arithmetic expression is suitably performed. have.
[0033]
That is, the software of the first control means 21 has a self-learning function, self-learns various cases, finds an optimal solution by applying a multivariable analysis theory, and creates an optimal operation expression. be able to.
[0034]
The second control unit 22 provides a feedback control signal to the small flow valve 8 of the flow control unit 5 based on the detection result of the back pressure sensor 15.
[0035]
As shown in FIG. 2, in the control unit 7 of the present embodiment, the control range of the back pressure is set to a basic part (base part B) that is feed-forward controlled by the first control unit 21 and a second control unit 22. And a fine adjustment part (control part C) that is feedback-controlled by the control unit. The base portion B is larger than the control portion C when viewed from the entire control range. Then, the control of the basic part B is achieved by the feedforward control of the first control means 21, and further, the control of the fine adjustment part (control part C) is achieved by the feedback control of the second control means 22. It is configured as follows.
[0036]
Conventional feedback control such as PID control has a problem that response time is slow and overshoot may occur, so that it takes a long time for the system to stabilize. However, in this example, the load distribution (determined fixed flow rate) is determined for each of the feedforward control and the feedback control, and most of the control amount (base portion B) is determined by the feedforward control as the base flow rate before the feedback result is obtained. The control method which gives quick is adopted. According to this example, since the ratio depending on the feedback control is small, even if a slight hunting occurs by increasing the sensitivity of the PID constant, the influence on the whole is small, and the base flow rate is calculated by a predetermined multivariable arithmetic expression. Since the calculation is performed quickly and given by the feedforward control, there is an advantage that the time until the target is achieved is short.
As described above, in the control device of the polymer electrolyte fuel cell, the function of the back pressure control device that controls the back pressure of the fuel cell, in particular, is the flow control means 5, the back pressure sensor 15, and the plurality of types. The first control means 21 for performing feedforward control of the flow control means 5 and the second control means 22 for performing feedback control of the flow control means 5 are calculated by a back pressure arithmetic expression having the physical property amount as a variable.
[0037]
(3) Operation The operation in the present embodiment will be described.
For example, a fuel injection amount is calculated from a target power generation current value (that is, a target power generation amount) corresponding to an accelerator pedal operation amount and the like, and this fuel injection amount is output as a fuel injection command to, for example, the fuel supply unit 3 or the like. In addition, a generated current command is calculated from the fuel injection command and output to the DC / AC converter 6 or the like to control the generated current output from the fuel cell 1.
[0038]
A target anode operating pressure (operating pressure of the fuel cell 1) is calculated based on the generated current command. Note that the target anode operating pressure is a predetermined pressure loss set according to the reaction efficiency of the fuel cell 1, that is, the pressure of the reformed fuel supplied to the fuel cell 1 and the pressure of the discharged fuel discharged from the fuel cell 1. (Back pressure), and a predetermined target anode operating pressure is set for the generated current output from the fuel cell 1. Further, based on the fuel injection command and the generated current command, the flow rate of the discharged fuel, that is, the flow rate of the off gas is calculated.
[0039]
Here, the first control means 21 determines the large flow rate of the discharged fuel flow rate control unit 7 by the feedforward control based on the given operating conditions based on the above-mentioned predetermined arithmetic expression using the large number of physical properties as variables. The valve opening of the valve 9 is calculated. At this time, there is no need to carry out calculations by taking in actual signals from various detectors (sensors) provided in each section of the apparatus, and the operation amount of the large flow valve 9 is immediately calculated from given operation conditions and calculation formulas. If this is given by feedforward control, quick control of the base portion B can be achieved.
[0040]
The second control unit 22 measures the back pressure of the fuel cell 1 based on a signal from the second pressure detector 15 (back pressure sensor), and calculates a feedback coefficient relating to the valve opening of the small flow valve 8. Calculate and feedback control the opening.
[0041]
In the low flow rate range of the discharged fuel, zero is output as the valve opening of the large flow valve 9 and a value calculated by feedback control is output as the valve opening of the small flow valve 8.
On the other hand, in the high flow rate range of the discharged fuel, the small flow rate valve 8 calculated by the feedback control so as to correct the valve opening degree of the large flow rate valve 9 in the feedforward control and the valve opening degree of the large flow rate valve 9. Is output as a valve opening command.
[0042]
As a method of switching the control method, for example, a method according to a past empirical rule prepared in advance or a method using a pressure upper / lower limit alarm can be used.
[0043]
Next, a processing procedure of signals and the like performed by the control unit 7 for controlling the valve opening of the small flow valve 8 and the large flow valve 9 of the flow control means 5 will be specifically described. First, in the first stage, when a target operating condition is given, the first control means 21 calculates the valve opening degree of the large flow valve 9 of the flow control means 5 from a multivariable arithmetic expression prepared in advance. Is calculated.
[0044]
Next, in the second stage, it is determined whether or not the calculated opening degree of the large flow valve 9 is smaller than a predetermined threshold.
If the result of this determination is “NO”, that is, if it is determined that it is in the high flow rate range of the discharged fuel, the opening of the small flow valve 8 is set to a predetermined opening, for example, an opening that is の of the maximum opening. Set. The second control means 22 calculates a feedback coefficient relating to the valve opening from the value of the back pressure, and performs feedback control of the valve opening of the small flow valve 8 by, for example, PID control.
[0045]
On the other hand, if the result of the determination is “YES”, that is, if it is determined that it is in the low flow rate range of the discharged fuel, the valve opening of the large flow valve 9 is fully closed. Then, as described in the case of “NO”, the feedback control amount of the opening of the small flow valve 8 is determined, and the valve opening of the small flow valve 8 is feedback-controlled by, for example, PID control.
[0046]
As described above, in the low flow rate region until the flow rate of the exhaust fuel passing through the flow rate control means 5 reaches the predetermined flow rate, the valve opening of the large flow valve 9 is fully closed, and the valve opening of the small flow valve 8 is The flow rate and the back pressure of the discharged fuel, that is, the pressure of the discharged fuel on the fuel cell 1 side are adjusted in a stepwise manner by the feedback control.
[0047]
On the other hand, in the high flow rate region after exceeding the predetermined flow rate, the valve opening degree of the large flow rate valve 9 is changed stepwise by feedforward control to change the back pressure of the discharged fuel relatively large and to reduce the small flow rate. The valve opening of the valve 8 is set to an intermediate opening, for example, 開 of the maximum opening, and the small flow valve 8 is changed according to the change of the valve opening of the large flow valve 9 for each step. Of the valve is controlled by feedback for fine adjustment.
[0048]
In this example, the load distribution (determined fixed flow rate) is determined for each of the feedforward control and the feedback control, and the majority of the control amount (the base portion B) is set as the base flow rate before the feedback result is obtained. Since the control amount is given and the control amount is calculated by using a predetermined calculation formula using a plurality of physical quantities as variables, the time required to achieve the target is very short. Further, since the ratio depending on the feedback control is small (the control part C), even if a slight hunting occurs by increasing the sensitivity of the PID constant, the influence on the whole is small.
As a result, highly accurate back pressure control can be performed while maintaining high responsiveness in a wide range from a small flow rate to a large flow rate.
[0049]
【The invention's effect】
According to the back pressure control device for a polymer electrolyte fuel cell according to the first aspect, the back pressure indicating the operation state of the polymer electrolyte fuel cell and having a plurality of physical properties correlated with the back pressure as variables is used. And a feed-forward control signal is supplied to the flow control means based on the operating conditions and the calculation formula, so that a large number of physical properties are determined in a complicated correlation. There is an effect that the back pressure control of the fuel cell is performed precisely and quickly, a predetermined power generation efficiency is secured, and a predetermined output can be obtained.
[0050]
According to the back pressure control device described in claim 2 or 3, when another physical quantity other than the variable of the arithmetic expression becomes a disturbance to the control system, this is self-learned and the other physical property is calculated. A function for creating a new arithmetic expression captured as a variable and, when control based on the arithmetic expression is suitably performed, recalculating the arithmetic expression based on the control result to create a more preferable new arithmetic expression. Therefore, there is an effect that more sophisticated back pressure control can be realized by self-learning various cases that may occur in the operation of the fuel cell.
[0051]
According to the back pressure control device described in claim 4, the basic part of the back pressure control is performed by feedforward control by the first control means, and the other fine adjustment parts are controlled by the second control. Since the control is performed by means of feedback control, the basic part, which is a large part of the control amount, can be quickly controlled by feedforward control calculated by a predetermined multivariable arithmetic expression, and the ratio of the fine adjustment part dependent on feedback control is reduced. Since there is little, the sensitivity of the PID constant is increased in the fine adjustment portion, and even if a slight hunting occurs, the influence on the whole is small. As described above, there are advantages that overshoot hardly occurs, the time required to achieve the target is short, and the entire control system is quickly stabilized.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a polymer electrolyte fuel cell provided with a back pressure control device according to the present invention.
FIG. 2 is an explanatory diagram schematically showing the contents and functions of control in a control unit of the back pressure control device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Solid polymer fuel cell, 1a ... Outlet, 2 ... Control device, 3 ... Fuel supply part, 4 ... Oxidant supply part, 5 ... Flow control means, 6 ... DC / AC converter, 7 ... Control part, 8 small flow valve, 9 large flow valve, 15 second pressure detector, 21 first control means, 22 second control means.

Claims (4)

Back pressure control of a polymer electrolyte fuel cell that controls the back pressure due to unreacted fuel and air discharged from the polymer electrolyte fuel cell using a polymer electrolyte membrane between the fuel electrode and the air electrode In the device,
Flow rate control means connected to an outlet of the polymer electrolyte fuel cell from which unreacted fuel and air are discharged,
A back pressure sensor for detecting the back pressure;
The operational condition of the polymer electrolyte fuel cell has an arithmetic expression of the back pressure, which indicates an operating state of the polymer electrolyte fuel cell and has a plurality of types of physical quantities correlated with the back pressure as variables. And a first control means for performing a calculation based on the calculation expression and providing a feedforward control signal to the flow control means based on the calculation result;
A back pressure control device for a polymer electrolyte fuel cell, comprising: When the other physical quantities other than the plurality of physical quantities become disturbances to the control based on the arithmetic expression, the first control performs a function of creating a new arithmetic expression by adding the other physical quantities as variables. 2. The back pressure control apparatus for a polymer electrolyte fuel cell according to claim 1, wherein said means is provided. The first control means has a function of creating a new arithmetic expression by recalculating the arithmetic expression based on the control result when control based on the arithmetic expression is suitably performed. The back pressure control device for a polymer electrolyte fuel cell according to the above. A second control unit that provides a feedback control signal to the flow control unit based on a detection result of the back pressure sensor,
The control range of the back pressure is divided into a basic part that is feed-forward controlled by the first control means and a fine adjustment part that is feedback-controlled by the second control means,
3. The control of the fine adjustment portion is achieved by feedback control of the second control device after achieving control of the basic portion by feedforward control of the first control device. 4. Or a back pressure control device for a polymer electrolyte fuel cell according to item 3.

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