JP2775890B2 - Control unit for fuel cell power generation system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device of a fuel cell power generation system for an electric vehicle power supply or the like.

[Conventional technology]

Recently, a fuel cell power generation system to be mounted on a vehicle has been developed as a power source for an electric vehicle aimed at reducing pollution.

By the way, a fuel cell power generation system in which a fuel cell and a fuel reformer are combined has a low response to load fluctuation as a general characteristic. In addition, it is difficult to make the output of the fuel cell follow a sudden load change with good responsiveness. Therefore, a backup storage battery is connected to the output side of the fuel cell as a power source for an electric vehicle, and when the vehicle is in a heavy load operation during running, the output shortage of the fuel cell is discharged from the storage battery during heavy load operation, and the light load and running It has been proposed to adopt a hybrid fuel cell power generation system in which a storage battery is float-charged with a surplus of the fuel cell output during stop-time no-load operation.

On the other hand, the storage battery has a problem that its life is greatly shortened due to repeated overcharging and overdischarging. In the hybrid fuel cell power generation system, the storage battery is always kept in an appropriate charged state to extend the life. At the same time, it is important to make it possible to supply stable power to the load.

That is, the charging and discharging characteristics of a storage battery for a lead storage battery are as shown in FIG. 5, and in the regions A and B in FIG.
When used in the overcharged and overdischarged states shown in the area, the stable reversible reaction breaks down and becomes irreversible. Repeated charging and discharging of the storage battery in this area not only degrades the battery characteristics but also significantly increases the life of the storage battery It is known to shrink. FIG. 6 shows the charging current-voltage characteristics of the lead-acid battery for each discharge amount (%), and the boundary line D in the figure represents the boundary of the charging allowable area. That is, as long as the battery is charged with the time rate current (charging current × C) represented by the solid line area below the intersection of the characteristic line expressed for each discharge amount (%) and the boundary line D, the recovery charging can be performed safely. If the rapid charging is repeatedly performed in the broken line region beyond the intersection, the performance deterioration of the storage battery proceeds early. In other words, when the storage battery is recharged, the amount of discharge at that time,
That is, appropriate charging conditions (allowable charging voltage and current) differ depending on the state of the remaining capacity.

Therefore, in order to recover and recharge the storage battery of the hybrid fuel cell power generation system used as the power source for the electric vehicle in the short period of time during the light load operation during the heavy load operation, the characteristic diagram of FIG. It is necessary to control the fuel cell power generation system such that the charging is performed under the charging conditions just below the limit of the allowable region described in.

Therefore, as a control method of the hybrid fuel cell power generation system that satisfies the above-described storage battery charging condition, the boundary line D of the charging allowable area is set based on the storage battery charging characteristics shown in FIG. The data of the charge control pattern corresponding to each state of charge of the storage battery along the way is stored in the memory of the controller. On the other hand, the amount of charge and discharge of the storage battery is continuously monitored by the amp-hour meter during operation, and The remaining capacity is obtained by calculation, and based on the comparison with the charge control pattern described above, the charge voltage of the storage battery,
In other words, under the condition that the output voltage of the fuel cell does not exceed the allowable charging voltage of the storage battery, the output of the fuel cell is controlled to recover the storage battery to the target charge amount (80 to 90%). Has been proposed by the present applicant (see Japanese Patent Application Laid-Open No. 1-211860).

[Problems to be solved by the invention]

However, the conventional control method described above has the following problems in practical aspects. (1) Since the charging control pattern is set based on the static charging characteristics of the storage battery, there is no problem when the load fluctuation is relatively slow, but depending on the driving conditions like an electric vehicle, When the load fluctuates greatly, it is difficult to accurately calculate the remaining capacity continuously at each time point because the voltage does not immediately follow the discharge of the storage battery. For this reason, it is difficult to recover and charge the storage battery to the target charge amount within a limited charge time during the operation of the vehicle, and to always keep the storage battery in an appropriate charge state.

(2) It is necessary to continuously monitor the remaining capacity of the storage battery. However, in practice, since the measurement error of the amp-hour meter is accumulated over time, the true remaining capacity of the storage battery is continuously measured. It is extremely difficult to grasp correctly.

The present invention has been made in view of the above points, and while accurately grasping the remaining capacity of a storage battery in a simple manner, stably maintaining a charge state close to a target charge amount at all times while making the storage battery follow a load change. It is an object of the present invention to provide a control device for a fuel cell power generation system which can be used, and particularly exhibits an excellent effect as a power source for an electric vehicle.

[Means for solving the problem]

According to the present invention, such a purpose is introduced to a fuel cell in a control device of a fuel cell power generation system that connects a storage battery to an output side of the fuel cell via a current adjusting unit and supplies power to a load. Fuel cell output adjusting means for controlling fuel gas and reaction air to adjust the power output of the fuel cell;
A battery voltage detecting means for detecting the voltage of the battery, a battery current detecting means for detecting the current of the battery, and an amount of discharged electricity of the battery within the time at predetermined intervals based on a detection output of the battery current detecting means. Calculating means for calculating, and based on the amount of discharged electricity, determining the amount of power generated by the fuel cell so as to supply the amount of electricity corresponding to the amount of discharged electricity to the storage battery during the next cycle and controlling the output adjusting means of the fuel cell This is achieved by providing a controller which gives a command and also gives a control command to the current adjusting means so that the output current of the current adjusting means does not exceed the allowable charging condition of the storage battery.

Further, according to the present invention, according to the present invention, in a control device of a fuel cell power generation system for connecting a storage battery to an output side of a fuel cell via a current adjusting unit and supplying power to a load,
Fuel cell output adjusting means for controlling fuel gas and reaction air introduced into the fuel cell to adjust the power generation output of the fuel cell, storage battery current detecting means for detecting the current of the storage battery, and storage battery for detecting the voltage of the storage battery Voltage detecting means, calculating means for calculating the average current and voltage of the storage battery within a predetermined period of time based on the detection outputs of the storage battery current detecting means and the storage battery voltage detecting means, and based on the average current and voltage. The amount of discharged electricity of the storage battery is determined from the determined state of charge of the storage battery, and the amount of power generated by the fuel cell is determined so that the amount of electricity corresponding to the amount of discharged electricity is supplied to the storage battery during the next cycle. A controller for giving a control command to the adjusting means and for giving a control command to the current adjusting means so that the output current of the current adjusting means does not exceed the allowable charging condition of the storage battery. Also it is achieved.

[Action]

In the above configuration, the allowable charging conditions (voltage, current) for the storage battery are not specified in the entire range of the remaining capacity of the storage battery,
Only the charge amount of the target charge amount (for example, 80 to 90%) is set and stored in the memory of the controller. When the storage battery is in a discharging state, such as during a start-up period of the fuel cell power generation system, the power generation of the fuel cell is set to a high output within a range not exceeding the allowable charging condition of the storage battery until the storage battery reaches the target charge amount. Charge quickly. Then, after the storage battery reaches the target charge amount, the discharge electricity amount or the average voltage of the storage battery within that time period at predetermined intervals,
The current is measured successively, and based on this, in the next cycle, under the allowable charging condition corresponding to the target charge amount, the controller adjusts the power output of the fuel cell so as to replenish the amount of electricity corresponding to the discharge amount of the storage battery in the previous cycle. Control.

Here, the control method in the case of applying the present invention to an electric vehicle power supply will be specifically described. First, in order to start operation of a vehicle from a halt state, first, power is supplied from a storage battery to auxiliary equipment of a fuel cell, and fuel cell power generation is performed. Start the system. When the fuel cell starts to generate power, the amount of power generation is increased to approximately 100% output, and the storage battery is rapidly charged until it reaches the target charge (80 to 90%). After the storage battery has recovered to the target charge amount, the amount of power consumption, or the average current and the average voltage of the storage battery are sequentially calculated by the calculation means at predetermined intervals (for example, one to several minutes), and based on the calculation result. Recovery charging of the storage battery is performed by increasing or decreasing the output of the fuel cell in the next cycle within a range that does not exceed an allowable charging condition corresponding to a predetermined target charge amount of the storage battery. When the storage battery has exceeded the target charge amount, when determining the power generation amount of the fuel cell in the next cycle, a coefficient (1 or less) of the discharge electricity amount of the storage battery in the cycle one step before is determined. By controlling the output of the fuel cell, the charge amount of the storage battery is adjusted.

In this way, by monitoring the charge / discharge state of the storage battery in units of a predetermined period, it is possible to accurately grasp the remaining capacity of the storage battery without accumulating measurement errors, and to control the running condition and load fluctuation of the electric vehicle. Without being performed, the storage battery can be constantly maintained at the target charge amount so as not to be overcharged or overdischarged, and stable power supply to the load can be performed.

〔Example〕

1 and 2 are control system diagrams of a fuel cell power generation system according to different embodiments of the present invention. First, the first
In the figure, 1 is a raw material tank storing a reforming raw material such as methanol, 2 is a reformer, 3 is a fuel cell, 4 is a DC-DC converter as an output current adjusting means of the fuel cell, and 5 is a drive for an electric vehicle. A load 6 as a motor is a backup storage battery, and these constitute a hybrid fuel cell power generation system. Reference numeral 7 denotes a raw material pump for feeding a reforming raw material from the raw material tank 1 to the reformer 2, 8 denotes an air blower for feeding combustion gas to a burner of the reformer 2, 9.
Reference numeral denotes an air blower for introducing reaction air to the fuel cell 3, and reference numeral 10 denotes an accessory controller as an output adjusting means for controlling these accessories and controlling the output of the fuel cell. The reformer burns off-gas of the fuel cell 3 to obtain reforming reaction heat, and supplies power to various auxiliary devices and the auxiliary device controller from the output side of the fuel cell 3. I have.

On the other hand, the storage battery 6
The output of the current detector 11 is taken at predetermined intervals by a current detector 11, an Amber hour meter 12 as a battery discharge amount detecting means for integrating the current detection value, a voltage detector 13, and a timer 14. An arithmetic unit 15 for calculating the amount of discharged electricity of the storage battery 6, and comparing the signal from the arithmetic unit 15 with the data of the allowable charging voltage set value described later stored in the memory in advance, the auxiliary controller 10, DC-DC The controller 16 that outputs the control command Ifc to the converter 4 constitutes a control system of the fuel cell power generation system. In addition, 17 is a controller of the DC-DC converter 4, 18 is an output current detector of the fuel cell 3, and 19 is a comparator.

In such a configuration, in an operation state in which the load is supplied from the fuel cell power generation system, the terminal voltage of the storage battery 6 is input to the controller 16 via the voltage detector 13 and the current of the storage battery detected by the current detector 11 is detected. The discharge current is converted into a discharge electric quantity within the time at predetermined intervals and inputted through an ampere hour meter 12 and a discharge electric quantity calculator 15.

On the other hand, the controller 16 sets the target charge amount of the storage battery 6 to
Assuming that the allowable charging voltage is 80 to 90%, the allowable charging voltage (corresponding to points a and b in FIG. 6) corresponding to the target charging amount is stored in the memory as a set value. Control. First, in a discharge state in which the terminal voltage of the storage battery 6 has dropped to or below the allowable charging voltage due to power supply to the auxiliary equipment, such as when starting up the fuel cell power generation system,
The control command Ifc is given to the auxiliary controller 10 and the DC-DC converter 4 so that the power generation amount of the fuel cell 3 becomes substantially 100% output, and the storage battery 6 is rapidly charged until it recovers to the target charge amount.

After the storage battery 6 recovers to a voltage corresponding to the target charge amount, the discharge is performed based on the discharge electricity amount of the storage battery 6 taken from the discharge electricity amount calculator 15 at predetermined intervals (for example, 1 to 3 minutes). The power generation amount of the fuel cell 3 is determined and the control command Ifc is output so that the electric amount corresponding to the electric amount is supplied to the storage battery 6 in the next cycle. This makes the accessory controller
In 10, the raw material pump 7, air blower 8,
9 to control the power output of the fuel cell 3. Also,
At the same time, the control command Ifc is compared with the detected value of the output current of the fuel cell in the comparator 19, and the controller 17 controls the DC-DC converter 4 so that the output current does not exceed the allowable charging current of the storage battery. . In the process of reviewing and controlling the power generation amount of the fuel cell every predetermined cycle as described above, if the voltage of the storage battery 6 exceeds the voltage range corresponding to the target charge amount (80 to 90%), The controller 16 outputs a value corrected by multiplying the amount of discharged electricity consumed by the storage battery in the cycle one step before by a coefficient smaller than “1” as the control command Ifc.

Next, an example of a control operation when applied to a power supply for an electric vehicle is shown in a time chart of FIG. In the drawing, T represents a measurement cycle of the amount of discharged electricity of the storage battery, and t represents a response delay of the fuel cell power generation system from the control command to a change in the power generation output. As is apparent from this figure, based on the information on the amount of discharged electricity of the storage battery measured in each cycle T, in the next cycle, the fuel is supplied so as to recharge the amount of electricity corresponding to the amount of discharged electricity of the storage battery in the previous cycle. The power generation of the battery is controlled to increase or decrease. FIG. 4 shows the change over time of the storage battery voltage corresponding to the control shown in FIG. 3, and the voltage of the storage battery is changed from the voltage corresponding to the target charge farming by charging after the start-up of the fuel cell power generation system. After the battery recovers to the point where the voltage of the storage battery is a and b in the figure (corresponding to a charge rate of 80 to 90%)
The charge and discharge are repeated according to the load fluctuation so as to fall within the range. This allows the storage battery to maintain a state of the target charge amount and to perform stable power supply to the load without shifting to an overcharged or overdischarged state.

FIG. 2 shows an embodiment different from FIG. 1, in which the amp-hour meter 12 and the electric discharge calculator 1 shown in FIG.
Instead of 5, an arithmetic unit 20 that takes in the outputs of the current detector 11 and the voltage detector 13 of the storage battery 6 and calculates an average current and an average voltage at predetermined intervals is adopted. It is the same as the figure.

In such a configuration, in an operation state in which the load is supplied from the fuel cell power generation system, the current and voltage of the storage battery 6 are input to the arithmetic unit 15 from the current detector 11 and the voltage detector 13 and are output for a predetermined period (eg, 1 to 3). Each minute), the average current and average voltage are calculated and given to the controller 10. On the other hand, the controller 10 stores in a memory various data relating to the allowable charging voltage and current based on the charging characteristics of the storage battery shown in FIG. 6, and stores the average current, The state of charge of the storage battery is determined by collating with the average voltage.

When the average current and average voltage of the storage battery 6 obtained from the computing unit 20 at a certain predetermined period are, for example, at point c in FIG. 6, the discharge amount of the storage battery at this predetermined period is about 25%.
%, And under the condition that the charging current does not exceed the charging current at the intersection d between the boundary line D, which is the allowable charging condition, and the discharge characteristic line corresponding to the discharging amount of 25%, the target charging amount ( 80
An appropriate power generation amount of the fuel cell 3 is determined so as to recover to 90%), and the controller 16 outputs a control command Ifc.

〔The invention's effect〕

Since the control device of the fuel cell power generation system according to the present invention is configured as described above, it has the following effects.

(1) The rechargeable battery incorporated in the hybrid fuel cell power generation system is recharged at the next cycle with an amount of electricity corresponding to the amount of discharged electricity of the storage battery at predetermined intervals based on the allowable charging conditions corresponding to the target amount of charge. By controlling the output of the fuel cell in such a manner, the storage battery is always maintained at the remaining capacity corresponding to the target charge amount during the operation of the power generation system, and stable power supply to the load can be performed.

(2) In the control, it is only necessary to set allowable charging conditions corresponding to the target amount of charge of the storage battery and monitor the amount of discharged electricity of the storage battery or the average voltage and average current of the storage battery at predetermined intervals. Can be handled by a simple control system. Moreover, unlike the conventional control method, it is not necessary to continuously measure the true remaining capacity of the storage battery, so that the state of charge of the storage battery can be accurately grasped without accumulating measurement errors.

(3) Therefore, excellent effects can be respectively exhibited as control devices of a hybrid fuel cell power generation system used in an application such as an electric vehicle in which the load greatly fluctuates depending on driving conditions.

[Brief description of the drawings]

1 and 2 are system diagrams of a control device according to an embodiment of the present invention, respectively, FIG. 3 is a diagram showing a time chart of a control operation according to the present invention, and FIG. 4 is a storage battery voltage accompanying the control of FIG. FIG. 5 is a charge / discharge characteristic diagram of the storage battery, and FIG. 6 is a charge current-voltage characteristic diagram of the lead storage battery. In the figure, 3: fuel cell, 4: DC-DC converter (current control means), 5:
Load, 6: storage battery, 10: auxiliary controller (output adjustment means), 11: current detector, 12: Amber hour meter, 13: voltage detector, 15: electric discharge calculator, 16: controller, 2
0: Average voltage and average current calculator, I fc: Control command.

Claims (2)

(57) [Claims] 1. A control device for a fuel cell power generation system for connecting a storage battery to an output side of a fuel cell via a current adjusting means to supply power to a load, wherein the control device controls fuel gas and reaction air introduced into the fuel cell. Fuel cell output adjusting means for adjusting the power output of the fuel cell, storage battery voltage detecting means for detecting the voltage of the storage battery, storage battery current detecting means for detecting the current of the storage battery, and detection output of the storage battery current detecting means. Calculating means for calculating the amount of discharged electricity of the storage battery within a predetermined period of time based on the calculated amount of electricity, and supplying an amount of electricity corresponding to the amount of discharged electricity to the storage battery during the next cycle based on the amount of discharged electricity. The power generation amount of the fuel cell is determined as described above and a control command is given to the output adjustment means of the fuel cell, and the control instruction is given to the current adjustment means so that the output current of the current adjustment means does not exceed the allowable charging condition of the storage battery. Control apparatus for a fuel cell power generation system characterized by a controller that gives. 2. A control device for a fuel cell power generation system for supplying power to a load by connecting a storage battery to an output side of a fuel cell via a current adjusting means, wherein a fuel gas and a reaction air introduced into the fuel cell are controlled. Means for adjusting the power output of the fuel cell, battery current detecting means for detecting the current of the battery, battery voltage detecting means for detecting the voltage of the battery, battery current detecting means and battery voltage detecting Calculating means for calculating the average current and voltage of the storage battery within a predetermined period based on the detection output of the means, and the amount of discharged electricity of the storage battery based on the state of charge of the storage battery determined based on the average current and voltage And determine the amount of power generation of the fuel cell so that the amount of electricity corresponding to this amount of discharged electricity is supplied to the storage battery during the next cycle, and give a control command to the output adjustment means of the fuel cell. The control device of a fuel cell power generation system characterized by the output current of the current regulating means and a controller for providing a control command to the current control means so as not to exceed the permissible charging condition of the battery.