JP2014056736A - Fuel cell system, method for controlling fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system for immediately supplying fuel gas to load fluctuation and promoting discharge of generated water without using complicated control algorithm.SOLUTION: A control section 7 of a fuel cell system has: a drive command value calculation section 32 which calculates a drive command value for every operation period; a storage section 30 which stores a drive command value less than a drive command threshold; a drive command value addition section 33; a threshold determination section 35 which determines whether or not a drive command addition value is equal to or more than the drive command threshold; an accumulation processing section 36 which accumulates the drive command addition value in the storage section when it is determined that the drive command addition value is less than the drive command threshold by the threshold determination section; and a drive control section 37 which drives a fuel gas supply valve on the basis of the drive command addition value when it is determined that the drive command addition value is equal to or more than the drive command threshold by the threshold determination section.

Description

  The present invention relates to a fuel cell system and a control method for the fuel cell system.

  It is known to use an injector as a hydrogen supply device of a fuel cell system. According to this injector, the supply amount of hydrogen can be adjusted by controlling the drive period, which is the valve opening time or the total time of the valve opening time and the valve closing time. can do.

  Further, according to Patent Document 1 below, a technique is disclosed in which the fuel cell system is controlled so that the drive cycle of the injector becomes long and the injector is periodically opened during low load operation.

JP 2007-165186 A

  However, according to the technique disclosed in Patent Document 1 described above, in response to a shortage of fuel gas that occurs irregularly due to load fluctuations, such as when the required power generation current of the fuel cell suddenly increases while the injector is closed, it is immediately The fuel gas could not be supplied.

On the other hand, in order to be able to supply fuel gas as soon as possible in the event of an inadequate fuel gas shortage, control should be performed so that the injector can be opened by interrupt processing even when the injector is closed. Can be considered.
However, it is not preferable that an interrupt process can be performed because the control algorithm of the injector is complicated and a high-performance microcomputer is required.

  In addition, according to the technique disclosed in Patent Document 1, since the drive cycle of the injector is prolonged and the valve closing time becomes longer, the drainage of generated water is deteriorated, and the power generation performance of the fuel cell is deteriorated. There was a risk of it.

  Therefore, the present invention was devised in view of the above-described background, and can quickly supply fuel gas against load fluctuations without using a complicated control algorithm, and can promote drainage of generated water. It is an object of the present invention to provide a fuel cell system and a method for controlling the fuel cell system.

  In order to solve the above problems, a fuel cell system according to the present invention is disposed on a fuel cell that generates power by being supplied with a fuel gas and an oxidant gas, and a supply path that supplies the fuel gas to the fuel cell. A fuel cell system comprising: a fuel gas supply valve that regulates and supplies the fuel gas by opening and closing drive; and a control unit that controls opening and closing drive of the fuel gas supply valve, wherein the control unit includes a predetermined calculation A drive command value calculation unit that calculates a drive command value of the fuel gas supply valve according to a load request of the fuel cell for each cycle, and a drive command that does not satisfy a drive command threshold that can promote drainage of generated water A storage unit that stores a value, a drive command value addition unit that adds a drive command value newly calculated by the drive command value calculation unit to the drive command value stored in the storage unit, and the drive command value addition By part When the threshold value determination unit that determines whether or not the issued drive command addition value is equal to or greater than the drive command threshold value and the threshold value determination unit determines that the drive command addition value does not satisfy the drive command threshold value In addition, when the storage processing unit that accumulates the drive command addition value in the storage unit and the threshold value determination unit determine that the drive command addition value is equal to or greater than the drive command threshold value, based on the drive command addition value And a drive controller for driving the fuel gas supply valve.

According to the present invention, even when the threshold value determination unit determines that the drive command addition value is less than the drive command threshold value, in other words, even if the fuel gas supply valve is driven to meet the load request of the fuel cell. When it is determined that the drainage of the generated water cannot be promoted, the drive command threshold is accumulated in the storage unit by the accumulation processing unit, and the fuel gas supply valve does not open in the calculation cycle.
On the other hand, when the threshold value determination unit determines that the drive command addition value is equal to or greater than the drive command threshold value, in other words, by driving the fuel gas supply valve to meet the load request of the fuel cell, When it is determined that drainage can be promoted, the drive control unit drives the fuel gas supply valve based on the drive command addition value. Therefore, an amount of fuel gas that can promote the drainage of the generated water is supplied, and the drainage of the generated water can be promoted.
That is, according to the present invention, when the fuel gas supply amount is small and the drainage effect is considered to be poor, the fuel gas is not supplied and the fuel gas is supplied when the drainage effect is obtained. There is no risk of power generation performance deterioration due to deterioration.
In addition, according to the present invention, since the fuel gas is not necessarily supplied every calculation cycle, the calculation cycle for determining whether to open or close the fuel gas supply valve can be set in a relatively short time. When the calculation cycle is set to a relatively short time, the opportunity for performing an open / close determination process for determining whether to open / close by driving the fuel gas supply valve increases. Therefore, even when the load request of the fuel cell suddenly fluctuates, the next open / close determination process is performed relatively early, and the combustion gas can be quickly supplied according to the load variation.
As described above, according to the present invention, fuel gas can be supplied promptly without interruption processing in response to load fluctuations that occur irregularly.

  The control unit determines whether or not power generation of the fuel cell is stable, and generates a valve opening flag when it is determined that power generation is not stable; A valve opening flag determining unit that determines whether or not the flag is set, and the drive control unit drives the drive when the valve opening flag determining unit determines that the valve opening flag is set. Preferably, the fuel gas supply valve is driven based on a command addition value.

  According to the configuration described above, the valve opening flag is set by the power generation stability determination unit when the power generation of the fuel cell is not stable. The valve opening flag determining unit determines that the valve opening flag is set, and the drive control unit drives the fuel gas supply valve to always open the valve. Therefore, combustion gas is reliably supplied and the power generation of the fuel cell can be stabilized.

  Further, the power generation stability determination unit is a means for determining whether or not the power generation of the fuel cell is stable, and the temperature of the fuel cell is within a predetermined temperature range where the catalyst activity is insufficient. Temperature determination means for determining whether or not the temperature determination means determines that power generation of the fuel cell is not stable when the temperature is within the predetermined temperature range, and sets the valve opening flag. It is preferable.

  According to the above-described configuration, when the fuel cell is in a catalyst inactive temperature state, for example, below freezing point, the temperature determination unit determines that the power generation of the fuel cell is not stable and sets the valve opening flag. Therefore, it is possible to continue the power generation of the fuel cell by reliably supplying the combustion gas, to promote the activation of the catalyst due to the temperature rise, and to continue the power generation of the fuel cell stably.

In addition, the power generation stability determination unit has a hydrogen concentration determination means for grasping the fuel gas concentration in the fuel cell as a means for determining whether or not the power generation of the fuel cell is stable,
Preferably, the hydrogen concentration determination means determines that the power generation of the fuel cell is not stable when the hydrogen concentration is equal to or lower than a predetermined concentration, and sets the valve opening flag.

  According to the above-described configuration, when the hydrogen concentration is equal to or lower than the predetermined concentration, the hydrogen concentration determination unit that grasps the hydrogen concentration determines that the power generation of the fuel cell is not stable, and the valve opening flag is set. Therefore, the fuel gas can be reliably supplied to increase the concentration of the fuel gas, and the power generation by the fuel cell can be stabilized.

  Further, the control unit determines whether or not it is necessary to promote drainage of the generated water, and determines that the valve opening flag is set when it is determined that it is not necessary to promote drainage. It is preferable to provide.

According to the configuration described above, when it is determined that it is not necessary to promote drainage, the drainage promotion determination unit sets the valve opening flag and performs processing so that the fuel gas supply valve is opened.
Therefore, the drive command addition value is not carried over to the next calculation cycle, and the fuel gas is supplied at the calculation cycle, so that temporary shortage of hydrogen can be reliably avoided.

  Further, the drainage promotion determination unit is a means for determining whether or not it is necessary to promote the drainage of the generated water. When the fuel cell is operated at a high load, the drainage promotion determination unit is predetermined after the high load operation ends. It has a high-load operation determination means for determining whether or not it is within a period, and the post-high-load operation determination means promotes drainage of the generated water when it is determined that it is within the predetermined period. The valve opening flag is preferably set as not necessary.

  According to the above-described configuration, a large amount of fuel gas is supplied and the generated water is drained within a predetermined period from the operation at a high load, that is, the operation at a high load, and the generated water remains in the supply path. If not, a valve opening flag is set by the determination means after high load operation. Therefore, the fuel gas is supplied in the calculation cycle without the drive command addition value being carried over to the next calculation cycle, and a temporary shortage of hydrogen can be reliably avoided.

  In addition, the control unit includes a moisture amount grasping unit capable of grasping the amount of the generated water, and the moisture amount grasping unit may change the drive command threshold to a large value when the grasped moisture amount is large. preferable.

  According to the configuration described above, the threshold value increases when the amount of water in the generated water is large, so the opportunity for the opening / closing determination process of the injector is reduced, but the opening time of the fuel gas supply valve when the valve opening process is performed is reduced. Can be longer. Therefore, the pressure in the anode flow path can be further increased, and the generated water remaining in the anode flow path can be reliably discharged.

  The control method of the fuel cell system according to the present invention includes a fuel cell that generates power by supplying fuel gas and oxidant gas, and a supply path that supplies the fuel gas to the fuel cell, and is operated by opening and closing. A control method of a fuel cell system, comprising: a fuel gas supply valve that regulates and supplies the fuel gas; and a control unit that includes a storage unit and controls opening and closing of the fuel gas supply valve, wherein the control The unit calculates a drive command value of the fuel gas supply valve according to a load request of the fuel cell for each predetermined calculation cycle, and promotes drainage of generated water stored in the storage unit. A step of adding the drive command value calculated in the calculation step to a drive command value less than a drive command threshold that can be performed, and whether or not the drive command addition value calculated in the adding step is equal to or greater than the drive command threshold Determine whether And a step of accumulating the drive command addition value in the storage unit when the drive command addition value is determined to be less than the drive command threshold value by the determination step, and a drive command addition by the determination step. And a step of driving the fuel gas supply valve based on the drive command addition value when it is determined that the value is equal to or greater than the drive command threshold value.

  According to the control method according to the present invention, the open / close determination process performed at each calculation cycle can cope with a sudden shortage of fuel gas that occurs irregularly and also promotes drainage of residual generated water. This eliminates the need for interrupt processing and simplifies the control algorithm.

  In addition, when the control unit determines that the power generation is not stable, the power generation stability determination unit that sets a valve opening flag, and when it is determined that there is no need to promote drainage of the generated water, One or both of a drainage promotion determination unit that sets a valve opening flag, a step of determining whether or not the valve opening flag is set after the adding step, and the valve opening flag is set If it is determined that the fuel command supply value is equal to or greater than the drive command threshold value, the fuel gas supply valve is driven based on the drive command addition value. Preferably, the step is performed.

According to the configuration described above, since it has the valve opening flag determination unit that determines whether or not the valve opening flag is set, from the viewpoint of power generation stability or from the viewpoint of the necessity of drainage of generated water From this, it is possible to determine whether or not the fuel gas supply valve can be opened.
Further, the step of determining whether or not the valve opening flag is set is prioritized over the step of determining whether or not the drive command addition value is equal to or greater than the drive command threshold. Therefore, when it is determined that the valve opening flag is set, the step of determining whether or not the drive command addition value is equal to or greater than the drive command threshold can be omitted, and simplification of the open / close determination process can be achieved.

  As described above, according to the present invention, there is provided a fuel cell system and a control method for the fuel cell system that can quickly supply fuel gas with respect to load fluctuations and promote drainage of generated water without using a complicated control algorithm. Can be provided.

It is a figure which shows the main structures of the fuel cell system which concerns on embodiment. It is a figure which shows the main structures of a control part. (A) is an accelerator opening degree map showing the relationship between the accelerator opening degree θ and the target power generation, and (b) is a valve opening time map showing the relation between the target power generation and the valve opening time. It is a flowchart of an open / close determination process. It is a table | surface which shows the opening / closing determination process in a 1st calculation period-a 6th calculation period. It is a figure which shows the valve opening / closing state of the injector in a 1st calculation period-a 6th calculation period.

  Next, a fuel cell system according to an embodiment of the present invention will be described with reference to the drawings as appropriate. The fuel cell system 1 according to the embodiment is mounted on a fuel cell vehicle (vehicle, moving body) (not shown) that travels by driving a motor 100. Note that the vehicle includes, for example, a four-wheeled vehicle, a three-wheeled vehicle, a two-wheeled vehicle, a unicycle, a train, and the like, and the moving body includes, for example, a ship and an aircraft.

  As shown in FIG. 1, a fuel cell system 1 includes a fuel cell stack 2 that generates power to supply electric power to a motor 100, an anode system 3 that supplies hydrogen (fuel gas) to the fuel cell stack 2, a fuel A cathode system 4 for supplying air (oxidant gas) to the battery stack 2; a scavenging system 5 for connecting the anode system 3 and the cathode system 4; a cooling system 6 for cooling the fuel cell stack 2; The accelerator opening sensor 8 is mainly provided. The fuel cell stack 2 has a configuration corresponding to a “fuel cell” recited in the claims.

The fuel cell stack 2 is formed by stacking a plurality of cells that generate electricity by electrochemical reaction of hydrogen gas and oxidant gas. The fuel cell stack 2 is provided with an output detector 2a and a cell voltage monitor 2b.
The output detector 2a detects a current value and a voltage value of the electric power supplied from the fuel cell stack 2 to the motor 100, and outputs the detected current value and voltage value to the control unit 7. .
The cell voltage monitor 2b detects a cell voltage for each of a plurality of cells, calculates an average cell voltage value and a minimum cell voltage value from the detected voltage for each cell, and calculates the calculated average cell voltage value, The lowest cell voltage value is output to the control unit 7.

  The anode system 3 includes a hydrogen tank 10 filled with high-pressure hydrogen of several tens of MPa, a supply path 11 for supplying hydrogen from the hydrogen tank 10 to the anode of the fuel cell stack 2, and an anode of the fuel cell stack 2. A discharge path 12 for discharging the discharged anode off gas to the diluter 23 and a circulation path 13 for circulating the anode off gas on the discharge path 12 to the supply path 11 are provided.

A main stop valve 14, an injector 15, and a pressure gauge 17 are provided on the supply path 11 of the anode system 3 in order from the upstream side (hydrogen tank 10 side). Further, a purge valve 16 is provided in the discharge path 12 of the anode system 3 on the downstream side (diluter 23 side) from the location where the circulation path 13 is connected.
The main stop valve 14, the injector 15, and the purge valve 16 are electromagnetic valves, and are driven (opened) when a drive current is supplied from a drive control unit 37 (see FIG. 2) described later of the control unit 7. It is supposed to be.
The injector 15 corresponds to a “fuel gas supply valve” described in the claims.

  The pressure gauge 17 measures the pressure of the gas supplied to the anode of the fuel cell stack 2, and is on the supply path 11 and downstream of the connection point of the circulation path 13 (on the fuel cell stack 2 side). The pressure on the downstream side of the supply path 11 is measured. The pressure gauge 17 outputs the measured pressure to the control unit 7 as hydrogen pressure information.

  The cathode system 4 includes an air pump 20 that compresses air (oxidant gas), a supply passage 21 that supplies air compressed by the air pump 20 to the cathode of the fuel cell stack 2, and cathode off-gas from the cathode of the fuel cell stack 2. A discharge path 22 for discharging, a diluter 23, and a hydrogen sensor 24 for detecting the hydrogen concentration of off-gas discharged from the diluter 23 are provided.

  The air pump 20 compresses outside air (air) and supplies the compressed air to the supply path 21 of the cathode system 4. The diluter 23 is for diluting the anode off gas flowing in from the discharge path 12 of the anode system 3 with the cathode off gas flowing in from the discharge path 22 of the cathode system 4 and discharging it to the outside. The hydrogen sensor 24 measures the amount of hydrogen contained in the off-gas discharged from the diluter 23 in order to measure the amount of hydrogen discharged from the fuel cell system 1. Further, the hydrogen sensor 24 outputs the measured hydrogen concentration to the control unit 7 as discharged hydrogen amount information.

  The cooling system 6 includes a refrigerant flow path 6a connected to the refrigerant flow path formed in the fuel cell stack 2, a temperature sensor 6b for measuring the temperature of the refrigerant flowing out of the fuel cell stack 2, and the refrigerant flow path 6a. And a radiator 6c for exchanging heat of the refrigerant, and a pump (not shown) for circulating the refrigerant. Moreover, the temperature sensor 6b outputs the measured refrigerant temperature to the control part 7 as refrigerant temperature information. It is assumed that the refrigerant temperature measured by the temperature sensor 6b is substantially equal to the temperature of the fuel cell stack 2.

The scavenging system 5 includes a scavenging path 5a that connects the supply path 21 of the cathode system 4 and the supply path 11 of the anode system 3, and a scavenging valve 5b that opens and closes the scavenging path 5a.
Then, the control unit 7 determines that the temperature estimated from the refrigerant temperature information input from the temperature sensor 7b is equal to or lower than a predetermined temperature value at which the generated water remaining in the anode system 3 of the fuel cell system 1 may freeze. In this case, the scavenging valve 5b is opened and the air pump 20 is driven to feed the compressed air through the scavenging passage 5a into the flow path of the anode system 3 and remain in the flow path of the anode system 3. A scavenging process for draining the generated water is performed. When the scavenging process is performed, the scavenging information is stored in the storage unit 30 (see FIG. 2).

  The accelerator opening sensor 8 is a sensor that detects an accelerator opening θ that is a depression amount of an accelerator pedal provided in a fuel cell vehicle (not shown). The accelerator opening sensor 8 outputs the detected accelerator opening θ to the control unit 7.

  The control unit 7 performs an opening / closing determination process for determining whether or not to open the injector 15 at regular intervals, and controls the opening / closing drive of the injector 15 based on the processing result of the opening / closing determination process. . In the following, a certain period in which the control unit 7 performs the open / close determination process is referred to as a calculation period.

Further, as shown in FIG. 2, the control unit 7 receives the cycle information and calculates a drive command value in the cycle by receiving the cycle unit, a storage unit 30 that stores information, a timer unit 31 that generates cycle information for each calculation cycle. A drive command value calculating unit 32 that calculates the drive command added value by adding the drive command accumulated value that is the drive command value accumulated in the storage unit 30 and carried over to the drive command value. A valve opening flag determination unit 34, a threshold determination unit 35 that determines whether or not the drive command addition value is greater than or equal to the drive command threshold value, an accumulation processing unit 36 that accumulates the drive command addition value in the storage unit 30, The drive control unit 37 that drives the injector 15 based on the drive command addition value, the power generation stability determination unit 38 that determines whether or not the fuel cell stack 2 has power generation stability, and promotion of drainage are necessary. Determine whether or not And a drainage promoting determining unit 39.
Although details will be described later, it is opened when the power generation stability determination unit 38 determines that the power generation stability is not present, and when the drainage promotion determination unit 39 determines that the promotion of drainage is not necessary. A valve flag is set. The valve opening flag is used to guide the opening / closing determination process by the control unit 7 so as to obtain a processing result that the injector 15 opens.

  The storage unit 30 is for storing information, and in addition to information input from each component of the fuel cell system 1, an accelerator opening map, a valve opening time map, a drive command accumulated value, A drive command threshold value is stored in advance.

As shown in FIG. 3 (a), the accelerator opening map predicts the power generation required for the fuel cell stack 2 from the accelerator opening θ (hereinafter referred to as “target power generation”). Etc. obtained in advance.
The relationship between the accelerator opening θ and the target power generation of the fuel cell stack 2 is as shown in FIG. 3A when the accelerator opening θ is large (when the depression amount is large) and the target rotation of the motor 100. Since the number increases, the target power generation of the fuel cell stack 2 also increases. On the other hand, when the accelerator opening θ is small (when the depression amount is small), the target rotational speed of the motor 100 decreases, so the fuel cell stack There is a correlation that the target generated power of 2 is small.

As shown in FIG. 3B, the valve opening time map is used to determine the hydrogen supply amount necessary for the generated power of the fuel cell stack 2 to become the target generated power. The valve opening time of the injector 15 necessary for the fuel cell stack 2 to achieve the target power generation can be derived.
The relationship between the target power amount of the fuel cell stack 2 and the valve opening time of the injector 15 is shown in FIG. 3 in order to increase the hydrogen supply amount when the target power amount of the fuel cell stack 2 is large. There is a correlation that the valve opening time of the injector 15 becomes longer, whereas when the target power amount of the fuel cell stack 2 is small, the valve opening time of the injector 15 becomes shorter in order to reduce the hydrogen supply amount.

  The drive command accumulated value is the valve opening time of the injector 15 accumulated in the storage unit 30 because the processing result that the injector 15 is not opened in the opening / closing determination process of the previous calculation cycle is obtained.

  Furthermore, the drive command threshold value is a value (see “S5” in FIG. 4) used by the threshold determination unit 35, and the injector 15 that can promote drainage of generated water remaining in the flow path of the anode system 3. It is the valve opening time.

The timer unit 31 receives the activation signal output from the control unit 7 and starts measuring time, and generates periodic information that is a start condition for the opening / closing determination process at regular intervals.
The timer unit 31 informs the drive command value calculation unit 32 of the cycle information generated at regular intervals. Thereby, the opening / closing determination process of the control unit 7 is performed at a constant cycle, that is, every calculation cycle.
Here, the calculation cycle timed by the timer unit 31 is set in advance, and a time equal to or longer than the time corresponding to the drive command threshold is secured.

  For the drive command value calculation unit 32, the drive command value addition unit 33, the valve opening flag determination unit 34, the threshold value determination unit 35, the accumulation processing unit 36, and the drive control unit 37 which will be described next, the cycle information from the timer unit 31 is used. Since it is the structure which is received and performed by the opening / closing determination process, it demonstrates along a process process, referring FIG.

As shown in FIG. 4, the drive command value calculation unit 32 is configured to receive the cycle information from the timer unit 31 (Start) and calculate the drive command value (S1).
Here, the drive command value is the valve opening time of the injector for supplying the hydrogen supply amount corresponding to the load demand of the fuel cell in the calculation cycle.
In the present embodiment, the calculation process of the drive command value by the drive command value calculation unit 32 is first performed based on the accelerator opening map (see FIG. 3A) stored in the storage unit 30. The target power generation of the fuel cell stack 2 is calculated from the accelerator opening θ input from 8.
Next, based on the valve opening time map (see FIG. 3B), the valve opening time of the injector 15 is calculated from the derived target generated power.

Here, the drive command value calculation unit 32 corrects the valve opening time of the injector 15 from the hydrogen pressure information input from the pressure gauge 17 or the hydrogen discharge amount information input from the hydrogen sensor 24. Yes.
In addition, when the hydrogen pressure is high and when the hydrogen discharge amount is small, the valve opening time is corrected so as to be shortened. On the other hand, when the hydrogen pressure is low and when the hydrogen discharge amount is large, the valve opening time becomes long. It is corrected as follows.
With the above processing, the valve opening time of the injector 15, that is, the drive command value is calculated. In addition, although the drive command value calculation part 32 in embodiment derives | leads-out the valve opening time of the injector 15 by the above-mentioned process, this invention is not limited to this.
The drive command value calculation unit 32 is configured to deliver the drive command value calculated by the above processing to the drive command value addition unit 33.

As shown in FIG. 4, when the drive command value adding unit 33 receives the drive command value from the drive command value calculating unit 32, the drive command value adding unit 33 reads the drive command accumulated value stored in the storage unit 30, and accumulates the drive command value. The drive command addition value is calculated by adding the value and the drive command value (S2).
Thus, the total time of the valve opening time of the injector 15 in the current calculation cycle and the valve opening time of the injector 15 accumulated until the previous calculation cycle carried over can be obtained. The drive command value adding unit 33 is configured to deliver the calculated drive command added value to the valve opening flag determining unit 34.
Note that, when the drive command accumulated value is read from the storage unit 30 by the drive command value calculating unit 32, the drive command accumulated value stored in the storage unit 30 is updated as “0”.

As shown in FIG. 4, the valve opening flag determination unit 34 is configured to determine whether or not the valve opening flag is set when the drive command addition value is received (S3).
Further, the valve opening flag determination unit 34 is configured to deliver the drive command addition value to the drive control unit 37 when it is determined that the valve opening flag is set (in the case of “Yes” in “S3”). Yes.

When the drive command addition value is received, the drive control unit 37 is configured to keep the drive current flowing in response to the drive command addition value in order to open the injector 15.
Therefore, when the drive control unit 37 receives the drive command addition value from the valve opening flag determination unit 34, the drive control unit 37 continues to flow the drive current so as to correspond to the drive command addition value (S4), and opens and closes during this calculation cycle. The determination process ends (in the case of “End 1”).

  On the other hand, the valve opening flag determination unit 34 is configured to pass the drive command addition value to the threshold determination unit 35 when it is determined that the valve opening flag is not set (in the case of “No” in “S3”). Has been.

As illustrated in FIG. 4, the threshold determination unit 35 is configured to determine whether the delivered drive command addition value is equal to or greater than the drive command threshold stored in the storage unit 30 (S5).
The case where it is determined that the drive command addition value is equal to or greater than the drive command threshold is a case where the valve opening time of the injector 15 can promote drainage of generated water remaining in the supply path 11 of the anode system 3. Point to.

Here, when the threshold value determination unit 35 determines that the drive command addition value is equal to or greater than the drive command threshold value (in the case of “Yes” in “S5”), the drive command addition value is transferred to the drive control unit 37. It is configured.
Then, the drive control unit 37 that has received the drive command addition value continues to drive the drive current so as to correspond to the drive command addition value (S6), and ends the open / close determination process during this calculation cycle ("End2" If).

  On the other hand, the threshold value determination unit 35 is configured to pass the drive command addition value to the accumulation processing unit 36 when it is determined that the drive command addition value is not equal to or greater than the threshold value (in the case of “No” in “S5”). .

When receiving the drive command addition value, the accumulation processing unit 36 accumulates (stores) the drive command addition value in the storage unit 30 as the drive command accumulation value so that the drive command addition value is carried over to the next calculation cycle. (S7).
Then, the drive command accumulated value is accumulated in the storage unit 30, and the open / close determination process during this calculation cycle is ended (End3).

Returning to FIG. 2, the description of each component in the control unit 7 is continued.
As shown in FIG. 2, the power generation stability determination unit 38 determines whether or not the power generation in the fuel cell stack 2 is stable. When it is determined that the power generation in the fuel cell stack 2 is not stable, the power generation stability determination unit 38 opens. The valve flag is raised to guide the processing result in the opening / closing determination process of the control unit 7 so that the injector 15 opens.
The power generation stability determination unit 38 includes a hydrogen concentration determination unit 50, a temperature determination unit 51, and a high output determination unit 52 in order to determine whether power generation in the fuel cell stack 2 is stable. Yes.

The temperature determination means 51 estimates the temperature of the fuel cell stack 2 based on the refrigerant temperature input from the temperature sensor 6b of the cooling system 6, and the estimated temperature of the fuel cell stack 2 is a predetermined catalyst activation insufficient temperature. It is configured to determine whether or not it is within the range.
Further, the temperature determination means 51 is configured to perform a process for setting a valve opening flag when it is determined that the temperature of the fuel cell stack 2 is within a predetermined catalyst activation insufficient temperature range.
In addition, the range of the catalyst activity insufficient temperature here is a range in which the power generation by the fuel cell stack 2 can be determined not to be stable because the catalyst is in an inactive temperature state such as 30 ° C. to 40 ° C. or below freezing point. It is.
Therefore, when the valve opening flag is set by the temperature determination means 51, hydrogen can be supplied to promote activation of the catalyst, and power generation by the fuel cell can be stabilized.

The hydrogen concentration determination means 50 determines whether or not the hydrogen concentration of the fuel cell stack 2 is less than a predetermined value by determining whether or not the average voltage value input from the cell voltage monitor 2b is less than a predetermined value. Is configured to determine.
Further, when the hydrogen concentration determination unit 50 determines that the voltage value of the cell is less than a predetermined value, the hydrogen concentration determination unit 50 performs a process of setting a valve opening flag by determining that the hydrogen concentration of the fuel cell stack 2 is less than the predetermined value. It is configured as follows.
Furthermore, the predetermined value here is a lower limit value of a normal voltage range required for the cell. When the average voltage value of the cell is less than a predetermined value, it is very low compared to the normal voltage value, and the concentration of hydrogen in the anode system 3 is not sufficiently high, that is, power generation is stable. This is a case where it can be determined that there is no such thing.
Therefore, when the valve opening flag is set by the hydrogen concentration determination means 50, hydrogen can be supplied to increase the hydrogen concentration, and the power generation by the fuel cell can be stabilized.
The hydrogen concentration determination means 50 determines whether or not the hydrogen concentration is less than a predetermined value based on the average voltage value input from the cell voltage monitor 2b. However, the present invention is not limited to this. .
For example, a hydrogen concentration sensor (not shown) is provided in the vicinity of the fuel cell stack 2 in the supply path 11, and it is determined whether or not the hydrogen concentration is less than a predetermined value based on the hydrogen concentration measured from the hydrogen concentration sensor. You may judge. Alternatively, it may be configured to determine whether or not the hydrogen concentration of the fuel cell stack 2 is less than a predetermined value based on the minimum voltage value input from the cell voltage monitor 2b.

Based on the accelerator opening θ detected by the accelerator opening sensor 8, the high output determination means 52 determines whether or not the acceleration requested for the motor 100 is equal to or greater than a predetermined value, and the motor 100 is requested. When it is determined that the acceleration is equal to or greater than a predetermined value, the valve opening flag is set.
The predetermined value here is a value that is considered to be insufficient for hydrogen when the motor 100 is driven at the required acceleration from the current hydrogen concentration.
Therefore, when the valve opening flag is set by the high output determination means 52, hydrogen can be supplied to avoid the shortage of hydrogen, and the power generation by the fuel cell can be stabilized.

As described above, in the power generation stability determination unit 38, when the valve opening flag is set by any one or more of the hydrogen concentration determination unit 50, the temperature determination unit 51, and the high output determination unit 52, the open / close determination process by the control unit 7 is performed. Thus, hydrogen is supplied without the drive command addition value being carried over to the next calculation cycle. Therefore, it is possible to reliably supply the combustion gas and stabilize the power generation of the fuel cell.
When each of the above-described means of the power generation stability determination unit 38 determines that the power generation in the fuel cell stack 2 is stable, the valve opening flag is canceled.

The drainage promotion determination unit 39 determines whether or not the promotion of drainage is necessary, and when it is determined that the promotion of drainage is not necessary, the valve opening flag is set and the injector in the opening / closing determination process by the control unit 7 This is for guiding 15 to open.
Further, the drainage promotion determination unit 39 determines whether or not the promotion of drainage is necessary, after the high load operation determination unit 53, after scavenging processing determination unit 54, and after drainage promotion control determination unit 55. And have.

After the high load operation is completed, the determination means 53 after the high load operation ends the high load operation when the fuel cell stack 2 performs a high load operation based on the current value and the voltage value of the fuel cell stack 2 detected by the output detector 2a. A determination is made as to whether or not it is within a predetermined period, and when it is determined that it is within a predetermined period, processing for setting a valve opening flag is performed.
Note that the predetermined period is a time derived in advance by a test or the like, and a large amount of hydrogen is supplied by high-load operation to drain the generated water, and the drained state, that is, the anode system 3 This is a period during which it can be determined that no produced water remains in the flow path.

Based on the scavenging information stored in the storage unit 30, the after-scavenging process determination unit 54 determines whether or not the scavenging process is within a predetermined period, and determines that the scavenging process is within the predetermined period. Is configured to perform a process of setting a valve opening flag.
The term “within a predetermined period” refers to a period during which the generated water is considered not to remain in the flow path of the anode system 3 due to the scavenging process.

Based on the command value information stored in the storage unit 30, the post-drainage promotion control determination unit 55 opens the injector 15 when it is determined that the drive command addition value is equal to or greater than the threshold (in the case of “End2”). Is determined for a predetermined number of times, and when it is determined that the predetermined number of times is continued, a process for setting a valve opening flag is performed.
Here, the predetermined number of times is the number of times that the generated water is considered not to remain because the valve opening of the injector 15 that can promote the drainage of the residual generated water is continuously performed.

As described above, in the drainage promotion determination unit 39, when the valve opening flag is set by any one or more of the after-high load operation determination unit 53, the after scavenging process determination unit 54, and the determination unit 55 after drainage promotion control. In the open / close determination process by the control unit 7, hydrogen is supplied without the drive command addition value being carried over to the next drive cycle, so that temporary shortage of hydrogen can be reliably avoided, and the power generation by the fuel cell stack 2 can be avoided. Stabilization can be further achieved.
It should be noted that the above-described means of the power generation stability determination unit 38 may be configured to perform a valve opening flag cancellation process when it is determined that drainage promotion is necessary.

Next, an operation example of the fuel cell system 1 according to the embodiment will be described with reference to FIGS. 5 and 6.
Note that in the period information generated by the timer unit 31, first the calculation cycle corresponding to the generated periodic information is referred to as a first operation period T ₁ receives the activation signal from the controller 7, the first calculation cycle T ₁ Subsequent calculation cycles are referred to as a second calculation cycle T ₂ , a third calculation cycle T _3, etc. in order. In addition, the calculation cycle counted by the timer unit 31 is 20 msec, and the drive command threshold value stored in the storage unit 30 is 10 msec.

As shown in FIG. 5, the drive command value calculated by the drive command value calculation unit 32 is 5 msec in the first calculation cycle T ₁ , 3 msec in the second calculation cycle T ₂ , and 6 msec in the third calculation cycle T _3. , in the fourth operation cycle _{T 4} 12 msec, and fifth calculation cycle _{T 5} in 3 msec, the sixth calculation cycle _{T 6} 8 msec.

Furthermore, it is assumed that the valve opening flag is not set in the first calculation cycle T ₁ to the third calculation cycle T ₃ , the fifth calculation cycle T ₅ , and the sixth calculation cycle T ₆ . Therefore, in the opening / closing determination processing of the first calculation cycle T ₁ to the third calculation cycle T ₃ , the fifth calculation cycle T ₅ , and the sixth calculation cycle T ₆ , description of the processing by the valve opening flag determination unit 34 is omitted.

First, the timer unit 31 receives the activation signal from the control unit 7, starts the counting of the first calculation cycle T ₁ of the injector 15, by sending periodic information to the drive command value calculation unit 32, the first closing determination process calculation period T ₁ is started.

As shown in FIG. 5, the first calculation cycle T _1, there is no previous calculation cycle. Therefore, the drive command accumulated value read from the storage unit 30 by the drive command value adding unit 33 is “0”, and the drive command added value in the first calculation cycle T ₁ is “5”.
Then, the threshold value determination unit 35 determines that the drive command addition value “5” is not equal to or greater than the drive command threshold value “10”, and the accumulation processing unit 36 stores the drive command addition value “5” as the drive command accumulation value. And the open / close determination process ends (in the case of “End3” in FIG. 4). Therefore, as shown in Figure 6, in the first operation period T _1, the injector 15 is not opened.

The second operation period T _2, as shown in FIG. 5, the drive command added value in the first calculation cycle T ₁ is being carried over, the drive command stored value is read by the drive command value addition unit 33 "5" The drive command addition value is “8”.
However, the threshold value determination unit 35 determines that the drive command addition value “8” is not equal to or greater than the drive command threshold value “10”, and the accumulation processing unit 36 stores the drive command addition value “8” in the storage unit 30 as the drive command accumulation value. accumulated and ends the second closing determination process of the operation cycle T ₂ (the case of "End3" in FIG. 4). Thus, as shown in Figure 6, also in the second calculation cycle T _2, the injector 15 is not opened.

In the third calculation cycle T _3, as shown in FIG. 5, the drive command stored value is "8", the driving command additional value after the addition is "14". Further, the threshold value determination unit 35 determines that the drive command addition value “14” is equal to or greater than the drive command threshold value “10”, and passes the drive command addition value “14” to the drive control unit 37. Then, the drive control unit 37 is a continuous flow of a driving current corresponding to "14" drive command additional value, closing the determination processing of the third calculation cycle T ₃ is completed (the case of FIG. 4 "End2"). Thereby, as shown in FIG. 6, the injector 15 opens for “14 msec”, and hydrogen is supplied to the fuel cell stack 2.
Here, as shown in FIG. 6, after opening determination processing of the third calculation cycle T ₃ is completed, the hydrogen concentration determination means 50, the voltage value of the cell is determined not to be greater than a predetermined value, sets a valve opening flag Suppose.

In the fourth operation cycle T _4, as shown in FIG. 5, the drive command stored value is "0", the drive command addition value calculated by the drive command value calculating section 32 is "12". Then, it is determined by the valve opening flag determination unit 34 that the valve opening flag is set, and the drive command addition value is transferred to the drive control unit 37.
Next, the drive controller 37 corresponds to "14" drive command additional value continues to flow a drive current, closing determination process in the fourth operation cycle T ₄ is completed (the case of FIG. 4 "End1"). As a result, as shown in FIG. 6, the injector 15 opens for “12 msec”.
Incidentally, the fourth in the calculation cycle T _4, the hydrogen is supplied voltage of the cell rises, the hydrogen concentration determination means 50, it is assumed that the cancellation process valve opening flag.

In the fifth operation cycle T _5, as shown in FIG. 5, the drive command stored value is "0", the drive command addition value calculated by the drive command value calculating section 32 is "3".
Therefore, since the drive command addition value “3” is not equal to or greater than the threshold value “10”, the accumulation processing unit 36 accumulates the drive command addition value “3” as the drive command accumulation value in the storage unit 30, and the fifth calculation cycle T ₅ The open / close determination process is terminated (in the case of “End3” in FIG. 4).
Thus, as shown in Figure 6, the fifth operation cycle T _5, the injector 15 is not opened.

In the sixth calculation cycle T ₆ , as shown in FIG. 5, the drive command accumulated value is “3”, and the calculated drive command added value is “11”. Then, the threshold value determination unit 35 determines that the drive command addition value “11” is equal to or greater than the threshold value “10”. Next, the threshold determination unit 35 passes the drive command addition value “11” to the drive control unit 37.
Next, a continuous flow of driving current drive control unit 37 corresponds to "14" drive command additional value, closing determination process in the sixth calculation cycle T ₆ is completed (the case of FIG. 4 "End2"). Therefore, as shown in FIG. 6, the injector 15 opens for “11 msec”.

As described above, according to the fuel cell system and the control method of the fuel cell system according to the embodiment, the drainage of the remaining generated water is promoted in the third calculation cycle T ₃ and the sixth calculation cycle T ₆ when the injector 15 is opened. An amount of hydrogen that can be produced is supplied. Therefore, it is possible to promote the drainage of the remaining generated water, and there is no possibility that the power generation performance is deteriorated due to the deterioration of drainage.

Further, according to the embodiment, the injector 15 is always opened every calculation cycle so that the injector 15 is closed in the first calculation cycle T ₁ , the second calculation cycle T ₂ , and the fifth calculation cycle T ₅ . Not controlled to valve.
Therefore, since hydrogen supplied to the fuel cell stack 2 does not become excessive, it is not necessary to make the calculation cycle of the injector 15 long as in the prior art, and the calculation cycle of the open / close determination processing is set to a relatively short time. be able to.

  Furthermore, according to the embodiment, since the calculation cycle is relatively short, the opportunity to perform the open / close determination process increases. Therefore, even if hydrogen shortage occurs due to sudden load fluctuations when the injector 15 is closed, the open / close determination process is performed relatively early, so that hydrogen can be supplied quickly.

In particular, according to the embodiment, when hydrogen shortage occurs as in the above-described fourth calculation cycle T ₄ , the valve opening flag is set by the power generation stability determination unit 38 and the drainage promotion determination unit 39. Therefore, the injector 15 is always opened. Therefore, hydrogen is reliably supplied to the fuel cell stack 2 and stable power generation of the fuel cell can be performed.

  Further, according to the embodiment, interrupt processing that is a complicated control algorithm is not required. Therefore, a high-performance microcomputer is not required, and an increase in manufacturing cost of the fuel cell system 1 can be avoided.

  The fuel cell system and the control method for the fuel cell system according to the embodiment have been described above, but the present invention is not limited to this.

In the embodiment, the drive command value derived from the valve opening time map is the valve opening time of the injector 15 that is expected to be necessary during the calculation cycle, but the present invention is not limited to this.
For example, the hydrogen supply amount expected to be required by the fuel cell stack 2 may be used as the drive command value. In this case, the processing target drive command value, drive command accumulated value, drive command addition value, and drive command threshold in the open / close determination process by the control unit 7 mean the hydrogen supply amount, and the drive control unit 37 It is necessary to modify the control so that the hydrogen supply amount corresponding to the drive command addition value can be supplied.

In addition, the control unit 7 of the fuel cell system 1 may include a moisture amount grasping unit (not shown) that can grasp the amount of generated water remaining in the flow path of the anode system 3.
This moisture amount grasping unit is arranged in the amount of generated water generated in the fuel cell stack 2 from the integrated value of the current value detected by the output detector 2a during the closing time of the purge valve 16, that is, in the flow path of the anode system 3. It is comprised so that the amount of generated water remaining may be grasped.
Further, the moisture content grasping unit determines whether or not the grasped generated water amount is larger than the predetermined amount, and when it is determined that the grasped generated water amount is larger than the predetermined amount, the threshold value stored in the storage unit 30 Is configured to change to a larger value.
Here, the predetermined amount is the amount of water that is determined to be unable to promote drainage with the threshold value stored in the storage unit 30 at the present time, in other words, with the valve opening time of the injector 15 stored at the current time. .

Therefore, according to the fuel cell system including the moisture amount grasping unit, when the threshold value stored in the storage unit 30 is changed to a large value by the moisture amount grasping unit, the injector 15 is opened and closed by the control unit 7. The valve opening time when the valve opening process is performed also becomes longer.
Therefore, even if the amount of moisture that cannot promote the drainage of the generated water remains in the flow path of the anode system 3 in the valve opening of the injector 15 before the change, according to the valve opening of the injector 15 after the change, It becomes possible to promote drainage of generated water.

1 Fuel cell system 2 Fuel cell stack (fuel cell)
7 Control unit 11 Supply path 15 Injector (fuel gas supply valve)
DESCRIPTION OF SYMBOLS 30 Memory | storage part 31 Timer part 32 Drive command value calculation part 33 Drive command value addition part 34 Valve opening flag determination part 35 Threshold value determination part 36 Accumulation processing part 37 Drive control part 38 Power generation stability determination part 39 Drainage promotion determination part 50 Hydrogen Concentration determination means 51 Temperature determination means 52 High output determination means 53 Determination means after high-load operation 54 Determination means after scavenging process 55 Determination means after drainage promotion control

Claims (9)

A fuel cell that is supplied with fuel gas and oxidant gas to generate electricity;
A fuel gas supply valve disposed on a supply path for supplying the fuel gas to the fuel cell, and adjusting and supplying the fuel gas by opening and closing drive;
A controller that controls opening and closing of the fuel gas supply valve;
A fuel cell system comprising:
The controller is
A drive command value calculation unit that calculates a drive command value of the fuel gas supply valve in response to a load request of the fuel cell for each predetermined calculation cycle;
A storage unit that stores a drive command value that does not satisfy a drive command threshold value that can promote drainage of generated water;
A drive command value adding unit that adds the drive command value newly calculated by the drive command value calculating unit to the drive command value stored in the storage unit;
A threshold value determination unit for determining whether or not the drive command addition value calculated by the drive command value addition unit is equal to or greater than the drive command threshold value;
An accumulation processing unit that accumulates the drive command addition value in the storage unit when the threshold determination unit determines that the drive command addition value is less than the drive command threshold;
A drive control unit that drives the fuel gas supply valve based on the drive command addition value when the threshold value determination unit determines that the drive command addition value is equal to or greater than the drive command threshold value;
A fuel cell system comprising: The controller is
A power generation stability determination unit that determines whether or not power generation of the fuel cell is stable and sets a valve opening flag when it is determined that power generation is not stable;
A valve opening flag determination unit for determining whether or not the valve opening flag is set,
The drive control unit drives the fuel gas supply valve based on the drive command addition value when the valve opening flag determination unit determines that the valve opening flag is set. The fuel cell system according to claim 1. The power generation stability determination unit is a means for determining whether or not the power generation of the fuel cell is stable. Whether or not the temperature of the fuel cell is within a predetermined temperature range where the catalyst activity is insufficient. Temperature determining means for determining whether
3. The fuel cell according to claim 2, wherein the temperature determination unit determines that the power generation of the fuel cell is not stable when the temperature is within the predetermined temperature range, and sets the valve opening flag. 4. system. The power generation stability determination unit includes a hydrogen concentration determination unit that grasps a fuel gas concentration in the fuel cell as a unit for determining whether power generation of the fuel cell is stable,
The hydrogen concentration determination means determines that the power generation of the fuel cell is not stable when the hydrogen concentration is equal to or lower than a predetermined concentration, and sets the valve opening flag. The fuel cell system described.   The control unit includes a drainage promotion determination unit that determines whether or not it is necessary to promote drainage of the generated water and sets the valve opening flag when it is determined that drainage is not required to be promoted. The fuel cell system according to any one of claims 2 to 4, wherein the fuel cell system is provided. The drainage promotion determination unit is a means for determining whether or not it is necessary to promote drainage of the generated water, and when the fuel cell is operated at a high load, within a predetermined period after the high load operation ends. Having a determination means after high load operation for determining whether or not
The said high-load driving | running determination means determines that it is not necessary to accelerate | stimulate drainage of the said produced | generated water when it is in the said predetermined period, The said valve-opening flag is set. Fuel cell system. The control unit includes a moisture amount grasping unit capable of grasping the amount of the generated water,
The fuel cell system according to any one of claims 1 to 6, wherein the moisture amount grasping unit changes the drive command threshold value to a larger value when the grasped moisture amount is large. A fuel cell that generates power by supplying fuel gas and oxidant gas; and
A fuel gas supply valve disposed on a supply path for supplying the fuel gas to the fuel cell, and adjusting and supplying the fuel gas by opening and closing drive;
A control unit that has a storage unit and controls opening and closing of the fuel gas supply valve;
A control method for a fuel cell system comprising:
The controller is
Calculating a drive command value of the fuel gas supply valve according to a load request of the fuel cell for each predetermined calculation cycle;
Adding the drive command value calculated in the calculation step to a drive command value that is less than a drive command threshold that can promote drainage of the generated water stored in the storage unit;
Determining whether the drive command addition value calculated by the adding step is equal to or greater than a drive command threshold;
A step of accumulating the drive command addition value in the storage unit when it is determined in the determination step that the drive command addition value is less than the drive command threshold;
Performing the step of driving the fuel gas supply valve based on the drive command addition value when it is determined in the determination step that the drive command addition value is equal to or greater than the drive command threshold value. Control method of fuel cell system. The controller is
A power generation stability determination unit that sets a valve opening flag when it is determined that the power generation is not stable;
When it is determined that it is not necessary to promote drainage of the generated water, a drainage promotion determination unit that sets the valve opening flag,
One or both of
Determining whether or not the valve opening flag is set after the adding step;
When it is determined that the valve opening flag is set, the process proceeds to the step of determining whether or not the drive command addition value is equal to or greater than the drive command threshold value, and based on the drive command addition value. The method for controlling the fuel cell system according to claim 8, wherein the step of driving the fuel gas supply valve is performed.

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