JP2001202980A - Processing method for excess reforming fuel gas in fuel- reform type fuel cell power source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable steady and efficient processing an excess hydrogen generated in the transition period of a fuel cell electric vehicle which is comprised of a reform type fuel cell system. SOLUTION: When a load change occurs, in which the load for a fuel cell electric vehicle is decreased, and the amount of load change exceeds the prescribed value, an output command value to a fuel cell 6 is lowered, and the excessive reform fuel gas in the fuel cell 6 is increased. The excess moisture generated in the fuel cell 6 is discharged by the excess reform fuel gas, which is increased in the fuel cell 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell electric vehicle equipped with a fuel cell power supply system in which an energy buffer such as a storage battery is combined with a fuel cell system including a fuel reformer. The present invention relates to a method for treating surplus reformed fuel gas in a fuel cell power supply system for treating high quality fuel gas.

[0002]

2. Description of the Related Art Conventionally, as one of fuel cell systems,
A so-called fuel reforming type fuel cell system is known.
In this fuel reforming type fuel cell system, a raw fuel gas obtained by evaporating a liquid raw fuel such as a water-methanol mixed liquid by an evaporator is supplied to a fuel reformer, and the fuel reformer provides a hydrogen-rich reformer. A high-quality fuel gas is generated, and the reformed fuel gas and air containing oxygen are supplied to a fuel cell and reacted to extract electric power. In recent years, a so-called fuel cell electric vehicle equipped with a fuel cell system has been actively developed, and a fuel cell system using a reformed fuel cell system equipped with a fuel reformer has also been developed.

[0003] In a fuel cell electric vehicle equipped with this fuel reforming type fuel cell system, when a transient state in which the load suddenly decreases, such as when decelerating or stopping, the load suddenly decreases.
Due to the presence of unevaporated raw fuel inside the evaporator, the volume of the entire system, the set pressure difference before and after the transient change, etc., the response speed of the fuel reformer system cannot keep up, and excessive hydrogen-rich excess reforming is necessary. Fuel gas may be generated. It is necessary to treat such surplus reformed fuel gas by some means.

As a conventional method for treating surplus reformed fuel gas, for example, a method is employed in which surplus power is directly generated by surplus reformed fuel gas in a fuel cell, and the surplus power is charged into an energy buffer such as a battery. Had been.

[0005] When the energy buffer cannot fully charge the surplus power, the surplus power is processed by a separately provided resistive load.

[0006] On the other hand, there has also been a method in which a surplus reformed fuel gas is subjected to combustion treatment by a combustor which heats an evaporator for vaporizing a liquid raw fuel.

[0007]

However, each of the above-mentioned prior arts has disadvantages. First, in the method of charging surplus power to the energy buffer,
If the charging area of the energy buffer is full, the energy buffer cannot be charged. For this reason, surplus power that cannot be fully charged must be consumed by a resistive load, and power is wasted. Also, the method of consuming power with a resistive load wastes power similarly.

On the other hand, surplus reformed fuel gas is supplied to the combustor by
In the combustion treatment method, when the excess reformed fuel gas is too large, a large amount of air must be supplied to the combustor in order to maintain the temperatures of the combustor and the evaporator at an appropriate level. Therefore, in order to supply a large amount of air to the combustor, a problem arises in that electric power for driving an auxiliary machine (such as a compressor) must be taken out of the energy buffer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel cell electric vehicle equipped with a fuel reforming type fuel cell system that reliably and efficiently eliminates excess reformed fuel gas generated during a transition without causing the above-mentioned disadvantages. So that it can be processed.

[0010]

SUMMARY OF THE INVENTION The present invention, which has solved the above-mentioned problems, is provided when a load of a fuel cell electric vehicle equipped with a fuel cell power supply system combining an energy buffer and a fuel cell system including a reformer is changed. A method of processing surplus reformed fuel gas, wherein a load change occurs in the fuel cell electric vehicle in which a load decreases, and when the load change amount exceeds a predetermined specified value, the electric power output from the fuel cell. Lowering the output command value of the fuel cell, reducing the consumption of reformed fuel gas on the anode side of the fuel cell, by passing the surplus reformed fuel gas through the fuel cell,
A method of treating a surplus reformed fuel gas in a fuel reforming fuel cell power supply system, comprising discharging at least a part of surplus moisture generated in the fuel cell to the outside of the fuel cell.

In the invention according to claim 1 of the present invention,
When the load of the fuel cell electric vehicle fluctuates, the output command value of the power output from the fuel cell is reduced, the amount of power generation using the reformed fuel gas is reduced, and the reformed fuel gas on the anode side of the fuel cell is reduced. Has reduced consumption. By reducing the consumption of the reformed fuel gas, the surplus reformed fuel gas increases because the fuel reformed gas containing the raw fuel remaining in the reformer system becomes a surplus. By utilizing the surplus reformed fuel gas and passing the surplus fuel reformed gas through the anode side of the fuel cell, the surplus moisture generated in the fuel cell is positively discharged. In this manner, the surplus reformed fuel gas generated when a load change occurs can be effectively used for preventing and recovering performance degradation due to adhesion of generated water and condensed water in the fuel cell. .

According to a second aspect of the present invention, the excess reformed fuel gas generated in the fuel supply section passes through the anode side of the fuel cell while maintaining the pressures of the anode and the cathode of the fuel cell within specified ranges. Thereby, while discharging at least a part of surplus moisture generated on the anode side of the fuel cell to the outside of the fuel cell, while maintaining the pressure difference between the anode and the cathode of the fuel cell at an appropriate value. The air supplied to the cathode is passed through the cathode, thereby discharging at least a part of excess water generated on the cathode side of the fuel cell to the outside of the fuel cell. 3 is a method for treating surplus reformed fuel gas in the fuel reforming type fuel cell power supply system of FIG.

When the output command value of the electric power output from the fuel cell is reduced and the surplus reformed fuel gas increases on the anode side in the fuel cell, the pressure on the anode side maintains the value corresponding to the high load before the output reduction instruction. Is done. At this time, in order to prevent the electrolyte membrane from being damaged or the like, it is necessary to keep the pressure difference between the cathode and the cathode at an appropriate value. In this regard, in the invention according to claim 2, since the pressures of the anode and the cathode of the fuel cell are maintained in the specified ranges, it is possible to prevent the electrolyte membrane from being damaged and to prevent the reformed fuel gas from passing through the anode. Thus, excess water on the anode side is discharged, and excess air on the cathode side is discharged by passing air through the cathode side. In this way, excess water generated on both the anode side and the cathode side can be discharged. In addition, by keeping the pressure on the cathode side higher than the pressure on the anode side, air can be sufficiently supplied to the CO remover, so that CO can be removed from the surplus reformed fuel gas, and the surplus reformed fuel gas can be removed. Can be kept low.

According to a third aspect of the present invention, at least a part of the excess moisture generated in the fuel cell is discharged to the outside of the fuel cell for a predetermined time by the excess reformed fuel gas passing through the anode of the fuel cell. After discharging, or after discharging at least a part of excess water generated in the fuel cell to the outside of the fuel cell by a predetermined amount of reforming fuel gas in the surplus reforming fuel gas, When the gas remains, the maximum current that can be generated by the surplus reformed fuel gas is used as an output command value, and at least one of driving of an auxiliary device of the fuel cell and charging of an energy buffer is performed with the fuel cell output. 2. The method according to claim 1, wherein
Alternatively, there is provided a method for treating surplus reformed fuel gas in the fuel reforming type fuel cell power supply system according to claim 2.

[0015] In the invention according to claim 3, after the excess moisture in the fuel cell is exhausted for a predetermined time by the excess reformed fuel gas, or by the predetermined amount of the excess reformed fuel gas, the fuel cell is exhausted. After exhausting excess water in the fuel cell, the maximum current that can be generated by the excess reformed fuel gas in the fuel cell is used as an output command value to generate power. This current is used for driving auxiliary equipment such as a compressor, or is charged in an energy buffer. Excess reformed fuel gas used for discharging excess moisture in the fuel cell is burned by a burner in a combustor. Here, when a large amount of excess reformed fuel gas is burned by the burner, it is necessary to prevent the burner from excessively heating. Therefore, oxygen is sent to the combustor by increasing the air supply amount of the air compressor. At this time, electric power for driving the air compressor is required, but since the output command value for the fuel cell has been lowered, electricity for driving the air compressor is taken out of the energy buffer. The surplus reformed fuel gas is used for charging the energy buffer after discharging excess water for a predetermined time or a predetermined amount of surplus reformed fuel gas in order to charge the taken-out electricity. Alternatively, auxiliary equipment such as an air compressor is directly driven by the generated current. Therefore, even if excess moisture is discharged by the excess reformed fuel gas, it is possible to prevent a situation in which the charge amount of the energy buffer becomes extremely small. Further, from the cell or stack voltage, it is possible to detect the performance recovery due to the discharge of excess moisture.

According to a fourth aspect of the present invention, at least one of driving of the auxiliary equipment of the fuel cell and charging of the energy buffer is performed for a predetermined time or by the SO of the energy buffer.
While performing until the C value reaches a predetermined value, the output voltage of the fuel cell is detected, and when the predetermined time has elapsed and at least one of the occurrence of the SOC value reaching the predetermined value occurs, When the output voltage has not recovered to a predetermined value and the surplus reformed fuel gas remains, at least a part of surplus moisture generated in the fuel cell is converted into a surplus reforming gas passing through the anode of the fuel cell. By the high quality fuel gas, for a predetermined time, after discharging to the outside of the fuel cell, or at least a part of surplus water generated in the fuel cell, the predetermined amount of the reformed fuel gas in the surplus reformed fuel gas Discharging to outside of the fuel cell, and thereafter, discharging at least one of driving of an auxiliary device of the fuel cell and charging of an energy buffer, and discharging of excess moisture in the fuel cell by excess reformed gas. It is a processing method of the surplus reformate gas in the fuel reforming type fuel cell power system according to claim 3, characterized in that repeated.

According to the fourth aspect of the present invention, after the auxiliary equipment is driven or the energy buffer is charged by using the surplus reformed fuel gas, if there is further surplus reformed fuel gas, the surplus reformed fuel gas is charged. The surplus moisture in the fuel cell can be discharged again by the surplus reformed fuel gas. Therefore, it is possible to effectively utilize the surplus reformed fuel gas. In addition, when the auxiliary machine is driven for the predetermined time and at least one of the SOC values of the energy storage reaches the predetermined value, if the excess reformed fuel gas still remains, the excess Excess water is discharged by the reformed fuel gas. Thereafter, by driving the auxiliary machine or charging the energy buffer and repeatedly discharging the excess water by the excess reformed fuel gas, the excess reformed gas can be effectively used. The “predetermined value” of “the output voltage has not recovered to the predetermined value” in the present invention is determined by the IV characteristics of the fuel cell.

According to a fifth aspect of the present invention, when the output possible value by the surplus reformed fuel gas becomes equal to the output command value, it is determined that there is no surplus reformed fuel gas, and the output command value is output to the output command value. A method for treating surplus reformed fuel gas in a fuel reforming fuel cell power supply system according to any one of claims 1 to 4, characterized in that:

According to the fifth aspect of the present invention, when the surplus reformed fuel gas is exhausted in the fuel cell, the output command value is returned to the original value, so that the surplus reformed fuel gas can be utilized without waste. it can.

[0020]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a reformed fuel cell power supply system in which surplus reformed fuel gas processing according to the present invention is performed.

As shown in FIG. 1, a reforming fuel cell power supply system (hereinafter, referred to as a "fuel cell power supply system") M in which surplus reforming fuel gas processing according to the present invention is performed is a liquid fuel, water. An evaporator 1 to which a methanol mixture F1 is supplied is provided. The supply amount of the water-methanol mixture F1 is appropriately adjusted by the pressure of the pump P1 and the opening of the supply valve V1. The evaporator 1 includes a heat exchange unit (not shown) that obtains a heat source from the combustor 2 and evaporates the water-methanol mixed liquid F1 to generate an evaporative gas. Downstream of the evaporator 1, a reformer 3 to which evaporative gas is supplied from the evaporator 1 is provided. Further, the combustor 2 is appropriately supplied with methanol F2. The supply amount of methanol F2 at this time is adjusted by the opening of the pump P2 and the supply valve V2. Further, the evaporator 1 and the combustor 2 are respectively provided with temperature detectors 1A and 2A for detecting their temperatures.

A fuel cell 6 is connected to the reformer 3 via a first heat exchanger 4A, a CO remover 5, and a second heat exchanger 4B. Gas is supplied to the fuel cell 6. Here, the CO remover 5 removes carbon monoxide contained in the fuel gas.

An air compressor 7 is connected to the fuel cell 6, and the air compressor 7 supplies air containing oxygen to the fuel cell 6. Then, in the fuel cell 6, the hydrogen in the reformed fuel gas and the oxygen in the air are electrochemically reacted to generate electricity by the reaction. The air supplied to the fuel cell 6 by the air compressor 7 is sucked from the atmosphere via the resonator 8 and the filter 9A, and the air is supplied to the intercooler 1.
The fuel gas is supplied to the fuel cell 6, the combustor 2, the reformer 3, etc. through the filter 0 and the filter 9B.

The fuel cell 6 is electrically connected to the high-pressure distributor 11, and the electric power generated by the fuel cell 6 is supplied to the high-pressure distributor 11. The high-pressure distributor 11 is electrically connected to a small-capacity, for example, 12 V, battery 13 via a DC / DC converter 12 and a PCU.
(Power control unit) 14 is connected to the main motor 15. The high-voltage distributor 11 is also connected to a large-capacity energy storage (charge-allowed area) 16 composed of, for example, a 288 V battery, which serves as an energy buffer of the present invention. As described above, the fuel cell power supply system M includes the fuel cell system including the reformer 3 and the battery 1.
3 in combination. A pressure gauge (not shown) is provided at the anode and cathode inlets, and an ammeter and a voltmeter for a distribution circuit (not shown) are provided in the high-pressure distributor 11. Further, the PCU 14 is provided with a timer (not shown). This timer discharges excess moisture in the fuel cell 6 discharged to the outside of the fuel cell 6 by the excess reformed fuel gas and air, and charges the energy storage 16 when checking the performance recovery of the fuel cell. Time is being measured. Further, the power generation amount of the fuel cell 6 and the charge amount of the energy storage 16 are output to the PCU 14.

The PCU 14 is connected to an air compressor motor 17. When the fuel cell power supply system M is started, methanol F which is a liquid fuel is used.
2 is supplied to the starting combustor 18. The fuel exhaust gas discharged from the fuel cell 6 is supplied to the combustor 2
Supplied to An anode back pressure valve V3 is provided between the fuel cell 6 and the combustor 2, and the pressure of the fuel gas supplied to the fuel cell 6 is adjusted by the opening of the anode back pressure valve V3. On the other hand, the surplus reformed fuel gas used for discharging the surplus water in the fuel cell 6 is also supplied to the combustor 2 as fuel exhaust gas, and the amount of the supplied gas is adjusted by the opening of the anode back pressure valve V3. You. Further, air containing oxygen is supplied from the air compressor 7 to the combustor 2 to prevent the combustor 2 from reaching an abnormally high temperature. Further, a cathode back pressure valve V4 is provided between the fuel cell 6 and the combustor 2. The amount of air supplied to the combustor 2 is adjusted by the opening of the cathode back pressure valve V4 and the rotation speed of the air compressor 7. Further, air is supplied from the air compressor 7 to the combustor 2 via the air supply valve V5 in order to prevent the combustor 2 from becoming abnormally high temperature. This air supply is
It is adjusted by the opening degree of the air supply valve V5 and the rotation speed of the air compressor 7.

Further, the fuel cell power supply system M includes an EC
A U (electronic control unit) 20 is provided. Control signals from the accelerator 21, the main motor 15, and the energy storage 16 are input to the ECU 20. Further, temperature signals from the temperature detectors 1A and 2A are also input. On the other hand, from the ECU 20, the PCU 14, the motor 17 for the air compressor, the pumps P1 and P2, the supply valve V
1, V2, anode back pressure valve V3, cathode back pressure valve V4,
And a control signal is output to the air supply valve V5.

The operation of the fuel cell power supply system M will be described. When the water-methanol mixture F1 is supplied to the evaporator 1, the water-methanol mixture F1 is evaporated by a heat exchanging unit (not shown) in the evaporator 1 by heat applied from the combustor 2 to evaporate. The evaporative gas thus obtained is supplied from the evaporator 1 to the reformer 3.

In the reformer 3, the evaporative gas mixed with air is brought into contact with a reforming catalyst to generate a hydrogen-rich reformed fuel gas. Most of this reformed fuel gas is
After being cooled by the heat exchanger 4A and selectively oxidized by the mixed air with the CO in the CO remover 5, the second heat exchanger 4
It is cooled by B and supplied to the fuel cell 6. Another part of the fuel gas is supplied to the combustor 2 and becomes a heat source of the evaporator 1.

The fuel cell 6 is supplied with air containing oxygen by an air compressor 7. In the process of reacting the hydrogen contained in the reformed fuel gas with the oxygen contained in the air in the fuel cell 6, electricity is generated from the fuel cell 6. Reformed fuel gas, air, and the like that cannot be consumed by the fuel cell 6 are supplied to the combustor 2 as off-gas.

The electricity generated by the fuel cell 6 is supplied to a high-pressure distributor 11. From the high voltage distributor 11, power is supplied to the battery 13 and the energy storage 16 via the DC / DC converter 12, and power is supplied to the main motor 15 via the PCU 14. From the battery 13, electric power is supplied to various automotive accessories such as an electric air conditioner, an electric power steering, lights, heaters, and load resistances. The wheels S are driven by rotating the main motor 15. On the other hand, electric power is also supplied from the PCU 14 to the air compressor motor 17.

The ECU 20 calculates the amount of power distribution in the high voltage distributor 11 based on various signals,
An output signal is transmitted to the high voltage distributor 11 and the PCU 14. That is, the main motor 1 is determined based on the accelerator opening that changes when a driver (not shown) operates the accelerator 21.
5 is calculated, and the required load signal is
0 is transmitted to the PCU 14. At this time, the ECU 20
In, the required output of the fuel cell 6 is obtained by obtaining the required load of the main motor 15 based on the accelerator opening and making corrections with reference to a map created in consideration of the power load of the auxiliary equipment. . The PCU 14 receives supply of electric power from the high-pressure distributor 11 and also receives the main motor 15 and the air compressor motor 1.
In response to the request of 7, the necessary power is supplied to each. Further, depending on the storage amount of the energy storage 16 and the required load of the main motor 15,
Is calculated, and a control signal is transmitted to the high voltage distributor 11. On the other hand, the operation amount of the pump P1 and the opening of the supply valve V1 are adjusted based on the temperature detected by the temperature detector 1A. Further, the operation amount of the pump P2 and the opening of the supply valve V2 are adjusted based on the temperature detected by the temperature detector 2A.

Next, a method of processing the surplus reformed fuel gas according to the present invention, which is performed in the fuel cell power supply system, will be described. FIG. 2 is a flowchart showing a general flow including a method for treating surplus reformed fuel gas according to the present invention. These controls are performed by the ECU 20. In the figure, the surplus reformed fuel gas is described as “RFG” for convenience. As shown in FIG. 2, before the method for processing the surplus reformed fuel gas according to the present invention is performed, normal control (S0) is performed, and in the process, an output instruction value for the fuel cell 6 is detected. (S1).
This output instruction value is detected according to the accelerator opening that changes by operating the accelerator shown in FIG. Next, based on the detected output instruction value, it is determined whether the output reduction rate exceeds a predetermined specified value, for example, 45% (S2). In step S2, the output reduction rate is 45%
In the following cases, the control returns to the normal control (S20).

On the other hand, when the output decrease value exceeds 45%, the processing of the surplus reformed fuel gas according to the present invention is started (S3). When the processing of the surplus reformed fuel gas is started, first, the cell voltage of the fuel cell before purging (discharging) the surplus moisture in the fuel cell 6 with the surplus reformed fuel gas is detected (S4). The cell voltage of the fuel cell 6 is detected by detecting the amount of charge to the energy storage 16 and calculating from the detected value. After detecting the cell voltage of the fuel cell 6, the output command value for the fuel cell 6 is subsequently reduced to, for example, 0 (S5). As described above, by setting the output command value for the fuel cell 6 to 0, the surplus reformed fuel gas in the fuel cell 6 is increased. By using the surplus reformed fuel gas, surplus water generated in the fuel cell 6 is discharged to the outside of the fuel cell 6 for a predetermined time, for example, 0.3 seconds (S6). The time for discharging the excess water is measured by a timer in the PCU 14.

Excess water in the fuel cell 6 is discharged to the outside of the fuel cell 6 by the surplus reformed fuel gas, and the excess water is discharged for a predetermined time.
After 3 seconds, the surplus reformed fuel gas in the fuel cell 6 is checked (S7). Then, it is determined whether or not there is excess reformed fuel gas (S8). If it is determined that there is no excess reformed fuel gas, the output instruction value for the fuel cell 6 is returned to the output command value (S21). Then, the surplus reformed fuel gas processing ends (S22). When the processing of the surplus reformed fuel gas is completed, the control returns to the normal control (S23).

On the other hand, if it is determined in step S8 that the surplus reformed fuel gas remains, the maximum current that can be generated by the surplus reformed fuel gas is used as the output command value (S9). The voltage is detected (S10).
A specific procedure for detecting the recovery cell voltage will be described later.
The detection of the recovery cell voltage is performed in a step of charging the energy storage 16 from the fuel cell 6.

In the step of detecting the recovery cell voltage, if the energy storage 16 is charged for, for example, 0.3 seconds, it is confirmed whether or not there is excess reformed fuel gas in the fuel cell 6 (S11). Then, it is determined whether or not there is excess reformed fuel gas (S12). If it is determined that there is no excess reformed fuel gas, the output instruction value for the fuel cell 6 is returned to the output command value (S21). Then, the surplus reformed fuel gas processing ends (S22). When the processing of the surplus reformed fuel gas is completed, the control returns to the normal control (S23). On the other hand, if it is determined that there is surplus reformed fuel gas, surplus water remaining in the fuel cell 6 is discharged to the outside of the fuel cell 6 again (S6).

Thereafter, the steps from step S6 to step S12 are repeated in the same manner. Then, when it is determined in step S8 or S12 that the surplus reformed fuel gas has run out, the output instruction value is returned to the output command value, and the processing of the surplus reformed fuel gas ends.

Next, the step of discharging the excess water in the fuel cell 6 by the excess reformed fuel gas to the outside of the fuel cell 6 in step S6 will be described. FIG. 3 is a flowchart showing a process of discharging the excess moisture in the fuel cell 6 to the outside of the fuel cell 6 by the excess reformed fuel gas.

As shown in FIG. 3, step S shown in FIG.
Following Step 5, or when it is determined in Step S12 that there is an excess reformed fuel gas, the excess moisture in the fuel cell 6 is discharged to the outside of the fuel cell 6 with the excess reformed fuel gas. Upon discharging the excess moisture in the fuel cell 6 to the outside of the fuel cell 6 with the excess reformed fuel gas, the flow rate of the reformed fuel gas on the anode side of the fuel cell 6 is detected,
A comparison is made with a predetermined reformed fuel gas flow rate first specified value (S3
1). The first specified value of the reformed fuel gas flow rate can be, for example, 2.5 l / sec. As a result, when the flow rate of the reformed fuel gas is smaller than the first specified value of the reformed fuel gas flow rate, the anode back pressure valve V3 is opened so that the amount of the reformed fuel gas in the fuel cell 6 does not become too small. The degree is reduced (S32). Note that the first specified value of the reformed fuel gas flow rate may be, for example, 2 l / sec instead of the above value.

Conversely, when the flow rate of the surplus reformed fuel gas in the fuel cell 6 is equal to or greater than the reformed fuel gas flow rate first specified value, the reformed fuel gas flow rate which is larger than the reformed fuel gas flow rate specified value 1 The flow rate second prescribed value is compared with the flow rate of the reformed fuel gas (S33). The second specified value of the reformed fuel gas flow rate can be, for example, 3 l / sec. When the first specified value of the reformed fuel gas flow rate is 2 l / sec, the second specified value of the reformed fuel gas flow rate can be 2.4 l / sec. As a result, when the flow rate of the reformed fuel gas is larger than the second specified value of the reformed fuel gas flow rate, the fuel cell 6
The opening degree of the anode back pressure valve V3 is increased so that the flow rate of the reformed fuel gas inside does not become too large (S34). Conversely, when the flow rate of the reformed fuel gas is equal to or less than the second specified value of the reformed fuel gas flow rate, the amount of the reformed fuel gas in the fuel cell 6 is an appropriate amount. The degree is maintained.

As described above, the surplus water in the fuel cell 6 is discharged to the outside of the fuel cell 6 by the surplus reformed fuel gas. Also, it is necessary to keep the burner temperature of the burner in the combustor 2 properly. Therefore, the anode back pressure valve V3
After the flow rate of the reformed fuel gas in the fuel cell 6 is adjusted by adjusting the opening of the fuel cell 6, the adjustment is performed so as to appropriately maintain the flow rate of the air supplied to the cathode side of the fuel cell 6.

To maintain the flow rate of the air supplied to the cathode side of the fuel cell 6 properly, the air compressor 7
To detect the flow rate of air supplied to the cathode side in the fuel cell 6 and compare it with a predetermined first predetermined value of the air flow rate (S3).
5). The first specified value of the air flow rate is, for example, 5 l / sec.
c. As a result, when the air flow rate is smaller than the first prescribed value, the opening degree of the cathode back pressure valve V4 is reduced so as to reduce the flow rate of the air supplied to the cathode side of the fuel cell 6 (S36). Note that the first prescribed value of the air flow rate is not the above value, but is, for example, 4 l / sec.
It can also be. Conversely, the air flow rate is
If it is equal to or more than the specified value, the second specified value of the air flow rate larger than the first specified value of the air flow rate is compared with the flow rate of the air supplied to the cathode side of the fuel cell 6 (S37). The second prescribed value of the air flow rate can be set to, for example, 6 l / sec. When the first specified value of the air flow rate is 4 l / sec, the second specified value of the air flow rate can be set to 4.8 l / sec. As a result, if the flow rate of the air supplied to the cathode side of the fuel cell 6 is larger than the second specified value of the air flow rate, the amount of air supplied to the cathode side of the fuel cell 6 is not excessively increased. The opening of the cathode back pressure valve V4 is increased (S38). On the other hand, when the flow rate of the air supplied to the combustor 2 is equal to or less than the second predetermined value of the air flow rate, an appropriate amount of air is supplied to the cathode side of the fuel cell 6, so that the cathode back pressure valve V4 The opening is maintained.

After adjusting the opening of the cathode back pressure valve V4 to adjust the flow rate of the air on the cathode side in the fuel cell 6, the pressure difference between the anode and the cathode in the fuel cell 6 is maintained at an appropriate value. Make that adjustment as you would. In order to adjust the inter-electrode differential pressure, the inter-electrode differential pressure between the anode and the cathode is detected, and the inter-electrode differential pressure is compared with a predetermined first predetermined differential pressure value (S39). The first specified value of the differential pressure can be, for example, 30 kPa. It should be noted that the first specified differential pressure value is not the above value, but may be, for example, 20 kPa. As a result, when the inter-electrode differential pressure is smaller than the first predetermined differential pressure value (the cathode is lower in pressure than the anode), the speed of the air compressor 7 is increased,
The amount of air supplied to the cathode side is increased (S40).
Here, in defining the speed of the air compressor 7, a map corresponding to the pressure and flow rate of the anode and the cathode is created. The amount of increase in the speed of the air compressor 7 can be determined by referring to this map.

Conversely, when the gap pressure is equal to or greater than the first pressure difference, the second pressure difference is compared with the second pressure difference greater than the first pressure difference (S41). This second specified value of the differential pressure can be, for example, 50 kPa. When the first specified differential pressure value is 20 kPa, the second specified differential pressure value can be 40 kPa. As a result, when the inter-electrode differential pressure is larger than the second specified differential pressure value, the speed of the compressor 7 is reduced so that the cathode does not become too high (S42). Also at this time, the speed of the compressor 7 is determined by referring to the map corresponding to the pressure and flow rate of the anode and the cathode. vice versa,
When the pressure difference between the electrodes is equal to or less than the second specified value of the pressure difference, the speed of the compressor 7 is maintained because the pressure difference between the electrodes is properly maintained.

In this way, adjustment of the pressure difference between the anode and the cathode is performed. At this time, at the anode,
The pressure is increased by the surplus reformed fuel gas, and the pressure of the anode and the cathode whose differential pressure is adjusted to an appropriate value naturally increases. Therefore, by increasing the pressure of the cathode, the excess water of the cathode can be effectively discharged to the outside of the fuel cell 6 as in the case of the anode.

After adjusting the pressure difference between the poles in this way, adjustment for maintaining the temperature of the burner 2A in the combustor 2 properly is performed. Therefore, the temperature of the burner in the combustor 2 is detected by the temperature detector 2A and is compared with a predetermined burner temperature first specified value (S43). As a result, when the burner temperature of the combustor 2 is lower than the first specified value of the burner temperature, the opening of the air supply valve V5 is reduced to increase the amount of air supplied to the combustor 2 ( S44) Prevent burner temperature from becoming too low.

Conversely, if the burner temperature in the combustor 2 is equal to or higher than the burner temperature first specified value, it is compared with a burner temperature second specified value higher than the burner temperature first specified value (S4).
5). As a result, when the burner temperature in the combustor 2 is higher than the second prescribed value of the burner temperature, the opening of the air supply valve V5 is increased. Then, the amount of air supplied to the combustor 2 is increased (S46) to prevent the burner temperature from becoming too high. Conversely, the burner temperature becomes the second burner temperature.
If the temperature is equal to or less than the specified value, the burner temperature is an appropriate value, and the opening of the air supply valve V5 is maintained.

Through the above steps, the step of discharging the excess moisture in the fuel cell 6 to the outside of the fuel cell 6 with the excess reformed fuel gas is completed, and the routine proceeds to step 7.

Next, the step of detecting the recovery cell voltage in step S10 will be described. FIG. 4 is a flowchart illustrating a process of detecting a recovery cell voltage.
When the purging of the excess moisture in the fuel cell 6 with the surplus reformed fuel gas is completed and the maximum current that can be generated by the surplus reformed fuel gas is set to the output command value in step S9, the surplus reformed fuel in the fuel cell 6 is set. The electric current generated by the gas is output to the energy storage 16 and charged. After completion of the purge step using the surplus reformed fuel gas, current is output for a predetermined duration T (S5).
1). When the current is output for the duration T, the amount of power W output from the fuel cell 6 to the energy storage 16 after the purge step using the surplus reformed fuel gas is detected (S52).
When the amount of power output to the energy storage 16 is detected, the SOC (state of c
harge) value is detected by a not-shown SOC detector (S53).

When the SOC value is detected, the output duration, the output power W, and the energy storage SOC value are set to the second value.
A comparison is made with a specified value (S54). Here, the second specified value includes all of the output time, the output power amount, and the SOC value. If any of the values is less than the second specified value, the process returns to step S51 to return to the predetermined time. During T, current is output.

On the other hand, if all of the output time, the output power, and the SOC value are equal to or more than the second specified value, the voltage of the recovery cell is detected from the output power (S55). And
The process proceeds to step S11 to check whether there is any surplus reformed fuel gas in the fuel cell 6.

In this manner, the surplus reformed fuel gas in the fuel cell 6 can be effectively used, and the surplus moisture in the fuel cell 6 can be effectively discharged to the outside of the fuel cell 6. Then, the performance of the fuel cell 6 can be recovered by discharging excess moisture in the fuel cell 6.

Next, the effects of the present invention will be described. FIG. 5 is a graph showing an example of the relationship between vehicle speed, reformed fuel gas consumption, and power generation voltage over time in a fuel cell electric vehicle. In the graph showing the generated voltage, the case where the surplus reformed fuel gas processing according to the present invention is performed after a sudden load decrease is shown by a solid line, and the surplus reformed fuel gas according to the present invention is indicated by a solid line. The case where no processing is performed is indicated by a broken line.

As shown in FIG. 5, after the fuel cell electric vehicle accelerates and runs at a constant speed, a load fluctuation occurs in which the vehicle speed sharply decreases. At this time, when the surplus reformed fuel gas processing according to the present invention is performed, the power generation voltage increases as compared with the case where the surplus reformed fuel gas processing according to the present invention is not performed. Therefore, it can be seen that the cell voltage in the fuel cell has recovered.

Thereafter, the vehicle accelerates after traveling at a constant speed, and at the same time the acceleration is completed, the vehicle decelerates and the load rapidly decreases. Also at this time, when the surplus reformed fuel gas processing according to the present invention is performed, the power generation voltage is higher than when no surplus reformed fuel gas processing is performed. Therefore, it was found that the cell voltage in the fuel cell was recovered.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in step S6 shown in FIG. 2, while a predetermined time is defined and the excess moisture is made to be outside the fuel cell by the excess reformed fuel gas, a predetermined amount of the excess reformed fuel gas is defined, and Excess water can be discharged by a fixed amount of surplus reformed fuel gas. On the other hand, the reformed fuel gas flow rate shown in FIG.
The prescribed value, the second prescribed value, the first prescribed value and the second prescribed value of the air flow rate, and the first prescribed value and the second prescribed value of the differential pressure are not limited to the above-mentioned values, but are suitably suitable values. It can be.

[0057]

As described above, claim 1 of the present invention
According to the present invention, the excess reformed fuel gas in the fuel cell is increased to utilize the excess moisture generated in the fuel cell for active purging. Therefore, the surplus reformed fuel gas generated when the load fluctuates can be effectively used for preventing and recovering performance deterioration due to adhesion of generated water and condensed water in the fuel cell. According to the second aspect of the present invention, air is supplied to the cathode side of the fuel cell, and the pressure on the cathode side is increased to maintain the gap-to-electrode pressure at an appropriate value.
Therefore, the gap pressure between the anode and the cathode is appropriately maintained, so that it is possible to prevent the electrolyte membrane from being damaged, and to discharge excess moisture generated on both the anode side and the cathode side. it can. Further, since air can be sufficiently supplied to the CO remover, CO can be removed from the surplus reformed fuel gas, and the CO concentration of the surplus reformed fuel gas can be kept low. According to the third aspect of the present invention, even when the excess moisture is discharged by the excess reformed fuel gas,
A situation in which the charge amount of the energy buffer becomes extremely small can be prevented.

According to the fourth aspect of the present invention, after charging the energy buffer using the surplus reformed fuel gas,
If there is a surplus reformed fuel gas, surplus water in the fuel cell can be discharged again by the surplus reformed fuel gas. Therefore, it is possible to effectively utilize the surplus reformed fuel gas. According to the invention of claim 5, when the surplus reformed fuel gas is exhausted in the fuel cell, the output command value is returned to the original value, so that the surplus reformed fuel gas can be utilized without waste.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a reformed fuel cell power supply system in which surplus reformed fuel gas processing according to the present invention is performed.

FIG. 2 is a flowchart of a method for processing surplus reformed fuel gas in the reformed fuel cell power supply system according to the present invention.

FIG. 3 is a flowchart showing a process of purging surplus moisture in the fuel cell 6 with surplus reformed fuel gas.

FIG. 4 is a flowchart illustrating a process of detecting a recovery cell voltage.

FIG. 5 is a graph showing an example of a relationship between a vehicle speed, a reformed fuel gas consumption, and a generated voltage in a fuel cell electric vehicle with time.

[Explanation of symbols]

 Reference Signs List 1 evaporator 2 combustor 3 reformer 4A, 4B heat exchanger 5 CO remover 6 fuel cell 7 air compressor 11 high-pressure distributor 16 energy storage (energy buffer) M reforming type fuel cell power supply system

Claims (5)

[Claims] 1. A method for treating surplus reformed fuel gas generated when a load of a fuel cell electric vehicle equipped with a fuel cell power system in which an energy buffer and a fuel cell system including a reformer are combined is changed. When a load change in which the load decreases in the fuel cell electric vehicle occurs and the amount of load change exceeds a predetermined specified value, the output command value of the power output from the fuel cell is reduced, and the anode side of the fuel cell is reduced. Reducing the consumption of the reformed fuel gas in the above, the excess reformed fuel gas passes through the inside of the fuel cell, at least a part of the excess water generated in the fuel cell to the outside of the fuel cell A method for treating surplus reformed fuel gas in a fuel reforming type fuel cell power supply system, wherein the gas is discharged. 2. The fuel cell according to claim 1, further comprising: passing excess reformed fuel gas generated in the fuel supply section through the anode side of the fuel cell while maintaining the pressures of the anode and the cathode of the fuel cell within specified ranges. While discharging at least a portion of the excess water generated on the anode side of the fuel cell to the outside of the fuel cell, the excess water is supplied to the cathode while maintaining the pressure difference between the anode and the cathode of the fuel cell at an appropriate value. 2. The fuel reforming fuel according to claim 1, wherein by passing air through the cathode, at least a part of surplus moisture generated on the cathode side of the fuel cell is discharged to the outside of the fuel cell. 3. A method for treating surplus reformed fuel gas in a battery power supply system. 3. A method according to claim 1, wherein at least a part of surplus moisture generated in the fuel cell is discharged to the outside of the fuel cell for a predetermined time by a surplus reformed fuel gas passing through an anode of the fuel cell, or At least a part of the excess moisture generated in the fuel cell, after discharging to the outside of the fuel cell by a predetermined amount of the reformed fuel gas in the surplus reformed fuel gas, when the surplus reformed fuel gas remains, A maximum current that can be generated by the surplus reformed fuel gas is used as an output command value, and at least one of driving of an auxiliary device of the fuel cell and charging of an energy buffer is performed with the fuel cell output. 3. A method for treating surplus reformed fuel gas in the fuel reforming fuel cell power supply system according to claim 1 or 2. 4. At least one of driving of an auxiliary device of the fuel cell and charging of an energy buffer is performed for a predetermined time or until the SOC value of the energy buffer reaches a predetermined value, and an output voltage of the fuel cell is detected. When at least one of the predetermined time has elapsed and the SOC value has reached a predetermined value, the output voltage has not recovered to the predetermined value and the surplus reformed fuel gas When remaining, at least a part of the excess moisture generated in the fuel cell, by a surplus reformed fuel gas passing through the anode of the fuel cell, for a predetermined time, after being discharged outside the fuel cell, or At least a part of the excess water generated in the fuel cell is discharged to the outside of the fuel cell by a predetermined amount of the reformed fuel gas in the surplus reformed fuel gas, and thereafter, 4. The fuel reformer according to claim 3, wherein at least one of driving of an auxiliary device of the fuel cell and charging of the energy buffer, and discharging excess water in the fuel cell by the excess reformed gas are repeated. For treating surplus reformed fuel gas in a portable fuel cell power supply system. 5. When the possible output value of the surplus reformed fuel gas becomes equal to the output command value, it is determined that there is no surplus reformed fuel gas, and the output command value is used as an output command value. Any one of claims 1 to 4
A method for treating surplus reformed fuel gas in the fuel reforming fuel cell power supply system according to any one of the first to third aspects.