JP2002063923A - Fuel cell circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to appropriately charge a battery without increasing the capacity of battery by appropriately controlling distribution state of current flowing in a fuel cell and a battery, and enable to maintain the output distribution of the fuel cell and the battery at a prescribed condition. SOLUTION: This is equipped with a fuel cell 11 whose both terminals are connected to a load and a voltage booster control circuit, and this has the battery 12 connected in parallel to the fuel cell 11 via a charging control circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel cell circuit.

[0002]

2. Description of the Related Art Conventionally, fuel cells have a high power generation efficiency and do not emit harmful substances. Therefore, fuel cells have been put to practical use as power sources for industrial and domestic use, or as power sources for artificial satellites and spacecraft. In recent years, development as a power source for vehicles such as passenger cars, buses, and trucks has been advanced.

[0003] The vehicle includes a lighting device, a radio,
It is equipped with a large number of auxiliary equipment that consumes electricity, such as a power window, which is used even when the vehicle is stopped, and has various running patterns and an extremely wide output range required for a power source. When a battery is used as a power source for a vehicle, a hybrid using a battery (a storage battery or a secondary battery) is generally used.

FIG. 2 is a diagram showing a conventional fuel cell circuit.

[0005] In the drawing, reference numeral 101 denotes a fuel cell, which is an alkaline aqueous solution type (AFC), a phosphoric acid type (PAFC), a molten carbonate type (MCFC), a solid oxide type (SOFC),
Although it may be a direct methanol (DMFC) or the like, a polymer electrolyte fuel cell (PEMFC) is generally used.

Reference numeral 102 denotes a battery which can be repeatedly discharged by charging, and is generally a lead storage battery, a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, a sodium sulfur battery, or the like.

Reference numeral 103 denotes an inverter (INV) which converts a DC current from the fuel cell 101 or the battery 102 into an AC current and supplies it to an AC motor (not shown) which is a driving source for rotating wheels of the vehicle. . When the drive source is a DC motor, the DC current from the fuel cell 101 or the battery 102 is directly supplied to the drive source without passing through the inverter 103.

In the fuel cell circuit having the above-described structure, the fuel cell 101 and the battery 102 are connected in parallel to supply a current to the inverter 103. When the fuel cell 101 is stopped, or when the current from the fuel cell 101 alone does not satisfy the required current during a high-load operation on a slope or the like, the inverter
Current is automatically supplied to the

When the AC motor, which is the driving source, functions as a generator during deceleration operation of the vehicle and generates a so-called regenerative current, the regenerative current is supplied to the battery 102 during the deceleration operation of the vehicle. , The battery 102
Is recharged. Further, even when the regenerative current is not supplied, when the battery 102 discharges and the terminal voltage decreases, the current generated by the fuel cell 101 is automatically supplied to the battery 102.

As described above, in the fuel cell circuit, when the battery 102 is constantly charged and the current from the fuel cell 101 alone does not satisfy the required current, the current is supplied from the battery 102 to the inverter 103. Since the vehicle is automatically supplied, the vehicle can run stably in various running modes.

[0011]

However, in the conventional fuel cell circuit, only the fuel cell 101 and the battery 102 are connected in parallel, and the distribution state of the current flowing through the fuel cell 101 and the battery 102 is changed. Is not controlled at all, the amount of current flowing through each of the fuel cell 101 and the battery 102 is determined by the current-voltage characteristics.

FIG. 3 is a diagram showing characteristics of a fuel cell and a battery in a conventional fuel cell circuit. In the figure, the horizontal axis represents current, and the vertical axis represents voltage and power.

In the drawing, reference numeral 105 denotes a curve showing the voltage-current characteristic of the fuel cell 101 (FIG. 2), and reference numeral 106 denotes the battery 1
A curve showing voltage-current characteristics of the fuel cell 1 is shown in FIG.
01 and the original voltage when battery 102 is summed-
A curve 108 indicating the current characteristic is a curve indicating the original power characteristic when the fuel cell 101 and the battery 102 are summed.

For example, during a constant load operation of the vehicle, the required current is satisfied only by the current from the fuel cell 101, so that the battery
Curve 10 although no current needs to be supplied to the
As shown in FIG. 6, the output of the battery 102 starts from a low current region, so that a current is also supplied from the battery 102 to the inverter 103. As described above, since the current always flows from the battery 102, it is necessary to increase the capacity of the battery 102. However, in general, the battery is large, heavy, expensive, and Increasing the capacity of 102 increases the volume and weight of the vehicle and increases the cost.

The fuel cell 101 and the battery 1
02 is set so that the voltage difference between them becomes small, even when the battery 102 is discharged and the terminal voltage is lowered, as shown by the curve 106, the fuel cell 101 Current from the battery 1
02, and it takes time to charge the battery 102. Therefore, the travel of the vehicle is restricted, and in the worst case, the battery 1
02 goes up.

Conversely, when the voltage difference is set to be large, a large current flows from the fuel cell 101 to the battery 10.
2, the battery 102 is destroyed by being overcharged.

Further, the voltage-current characteristics of the battery usually fluctuate depending on the remaining capacity.
And maintaining the output distribution of the battery 102 in a predetermined state,
It is difficult to exhibit the original current-voltage characteristics or power characteristics when the fuel cell 101 and the battery 102 as shown by the curves 107 and 108 are added. Therefore, as in the case of high-load operation on a slope or the like, the fuel cell 101
Even if the current from the battery 102 alone does not satisfy the required current, the current is not supplied from the battery 102 to the inverter 103, so that the running of the vehicle is restricted, or the remaining capacity of the battery 102 decreases. Even
The current is not supplied from the fuel cell 101, and the battery 102 rises.

The present invention solves the above-mentioned problems of the conventional fuel cell circuit, appropriately controls the distribution of current flowing through the fuel cell and the battery, and can appropriately increase the capacity of the battery without increasing the capacity of the battery. It is an object of the present invention to provide a fuel cell circuit capable of charging a fuel cell and maintaining the output distribution of the fuel cell and the battery in a predetermined state.

[0019]

For this purpose, in a fuel cell circuit according to the present invention, a fuel cell, a load connected to an output terminal of the fuel cell, and a load are connected in parallel with the fuel cell. A fuel cell circuit including a connected secondary battery circuit, wherein the secondary battery circuit includes a secondary battery having a lower voltage than the fuel cell as a reference voltage, and an output voltage of the secondary battery that is boosted. The fuel cell system includes a booster circuit for supplying a load, and a charging circuit for charging the secondary battery with a current output from the fuel cell.

According to another aspect of the present invention, there is provided a fuel cell circuit comprising a fuel cell connected to a load, and a secondary cell circuit connected in parallel to the fuel cell and the load. A charging switching element and a boosting switching element connected in series with each other, a secondary battery connected in parallel to the boosting switching element via a reactor,
A diode element arranged so that current from the load or the secondary battery is not supplied to the fuel cell.

In still another fuel cell circuit according to the present invention, the load is a drive control device of a drive motor for driving a vehicle.

In still another fuel cell circuit according to the present invention, the load is an inverter device of a drive motor for driving a vehicle.

[0023]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a conceptual diagram of a fuel cell circuit according to an embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a fuel cell (FC) circuit, which is used as a power source for vehicles such as passenger cars, buses, and trucks. Here, the vehicle is provided with a large number of auxiliary devices that consume electricity, such as lighting devices, radios, and power windows, which are used even when the vehicle is stopped. Since the required output range is extremely wide, the fuel cell 11 and the battery 12 are used in combination as power sources.

Reference numeral 11 denotes a fuel cell, such as an alkaline aqueous solution type (AFC), a phosphoric acid type (PAFC), a molten carbonate type (MCFC), a solid oxide type (SOFC), and a direct type methanol (DMFC). However, it is preferable that the fuel cell is a polymer electrolyte fuel cell (PEMFC).

More preferably, hydrogen is used as fuel,
PEMFC (proton) using oxygen or air as an oxidizing agent
exchange membrane fuel
cell) type fuel cell or PEM (proton
This is a so-called xchange membrane type fuel cell. Here, the PEM fuel cell generally has a cell (fuel) in which a catalyst, an electrode, and a separator are combined on both sides of a polymer membrane that transmits ions such as protons.
cell) in series (stac)
k) (see Japanese Patent Application Laid-Open No. 11-317236).

For example, in the present embodiment, a PEM fuel cell is used as an example, and a stack in which 400 cells are connected in series is used. In this case, the total electrode area is 300 [cm ² ], and the open terminal voltage is about 350
[V], the output is about 50 [kw]. The temperature during the steady operation is about 50 to 90 [° C.].

The hydrogen as the fuel can be supplied directly to the fuel cell by reforming methanol, gasoline, or the like by a reformer (not shown).
In order to stably supply a sufficient amount of hydrogen even during high-load operation of a vehicle, a hydrogen storage alloy,
It is desirable to supply hydrogen stored in a hydrogen gas cylinder or the like. As a result, hydrogen is always sufficiently supplied at a substantially constant pressure, so that the fuel cell 11 can supply a necessary current by following the fluctuation of the load of the vehicle without delay.

In this case, the output impedance of the fuel cell 11 is extremely low and can be approximated to zero.

Reference numeral 12 denotes a battery (storage battery) as a secondary battery that can be repeatedly discharged by charging, and is generally a lead storage battery, a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, a sodium sulfur battery, or the like. However, high-performance lead-acid batteries, lithium-ion batteries, sodium-sulfur batteries and the like used for electric vehicles and the like are desirable.

For example, in the present embodiment, a high-performance lead-acid battery is used as an example. In this case, the open terminal voltage is about 210 [V], and the capacity is such that a current of about 10 [kW] can be supplied for about 5 to 20 minutes.

An inverter device 13 is a drive control device serving as a load. The inverter device converts a DC current from the fuel cell 11 or the battery 12 into an AC current, and rotates a vehicle wheel. 14. Here, the motor 14 also functions as a generator, and generates a so-called regenerative current during deceleration operation of the vehicle. In this case, since the motor 14 is rotated by the wheels to generate power, the motor 14 applies a brake to the wheels, that is, functions as a vehicle braking device (brake). Then, as described later, the regenerative current is supplied to the battery 12, and the battery 12 is charged.

Reference numeral 15 denotes a battery charge control circuit, which is a parallel circuit of an IGBT (insulated gate bipolar transistor) 15a, which is a high-speed switching element as a charging switching element, and a thyristor 15b. Here, the IGBT 15a allows a current of about 200 [A].

On the other hand, reference numeral 16 denotes a battery discharge control circuit serving as a boosting control circuit, similar to the battery charge control circuit, and an IGBT 16a serving as a boosting switching element.
And a thyristor 16b in parallel. Here, the I
The GBT 16a allows a current of about 200 [A].

Reference numeral 17 denotes a reactor which allows a current of about 200 [A], and constitutes a booster circuit together with the battery discharge control circuit 16 to boost the output voltage of the battery 12.

Here, the IGBT 16a in the battery discharge control circuit 16 has a predetermined period (for example, 20 [kHz]).
z]) is turned on / off by a switching signal. When the IGBT 16a is turned on, the DC current output from the battery 12 flows to the reactor 17 to store energy, and when the IGBT 16a is turned off, a voltage corresponding to the energy stored in the reactor 17 is: The voltage is added to the output voltage of the battery 12 and boosted. The boosted output voltage of the battery 12 can be appropriately adjusted by the switching signal, but is adjusted to be slightly higher than the output voltage of the fuel cell 11.

The thyristor 16b in the battery discharge control circuit 16 is provided with an insulation between the emitter and the collector by the back electromotive force generated between the emitter and the collector of the IGBT 16a when the IGBT 16a is turned off. To prevent it from being destroyed.

Reference numeral 18 denotes a current sensor for measuring a current value flowing through the circuit. Reference numeral 19 denotes a thyristor as a diode element disposed so that current from a load or a secondary battery is not supplied to the fuel cell. is there.

Reference numeral 20 denotes a hybrid circuit electronic control unit, which includes arithmetic means such as a CPU, storage means such as a semiconductor memory, an input / output interface, etc., and measures a current value, a voltage value, and the like in the fuel cell circuit 10. At the same time, the operation of the battery charge control circuit 15 and the battery discharge control circuit 16 is controlled. Further, the hybrid circuit electronic control unit 20 is communicably connected to other sensors in the vehicle and other control devices such as a vehicle electronic control unit 21, a fuel cell electronic control unit 22, and an ignition control device 24, which will be described later. Then, the operation of the fuel cell circuit 10 is comprehensively controlled in cooperation with another sensor and another control device.

The hybrid circuit electronic control unit 20 may exist independently, for example, may exist as a part of another control device such as the vehicle electronic control unit 21. .

Here, for example, in the present embodiment, the hybrid circuit electronic control unit 20
I / O interface with two current sensors 18, two I / O interfaces for voltage measurement, I / O interface for battery charge control circuit 15, I / O interface for battery discharge control circuit 16, and electronic control unit 21 for vehicle An input / output interface, an input / output interface for the fuel cell electronic control unit 22, and an input / output interface for the ignition control device 24 are provided. The hybrid circuit electronic control unit 20 also includes a power supply interface connected to a power supply battery 23 as a power supply.

Next, the vehicle electronic control unit 21 sets C
It is provided with arithmetic means such as PU, storage means such as semiconductor memory, input / output interface, etc., and detects vehicle speed, temperature, accelerator opening, etc., and comprehensively controls the entire operation of the vehicle including the transmission, the braking device, and the like. .

Further, the fuel cell electronic control unit 22 comprises:
It is provided with arithmetic means such as a CPU, storage means such as a semiconductor memory, an input / output interface, and the like. Control behavior.

The power supply battery 23 is composed of a battery such as a lead storage battery, a nickel cadmium battery, a nickel hydride battery, a lithium ion battery, a sodium sulfur battery or the like, which can repeat discharging by charging.
[V] DC current is supplied to the hybrid circuit electronic control unit 20. The power battery 23 is
A direct current may be supplied as a power source to auxiliary equipment such as a vehicle radio and a power window.

The ignition control device 24 is a device for activating the fuel cell circuit. When the driver turns on the switch, the signal is transmitted to the hybrid circuit electronic control unit 20 and other devices. I do.

Next, the operation of the fuel cell device having the above configuration will be described.

FIG. 4 is a diagram showing characteristics of the fuel cell and the battery according to the embodiment of the present invention. In FIG. 4, the horizontal axis indicates the current value A, and the vertical axis indicates the voltage V and the power KW.

In FIG. 4, reference numeral 41 denotes a curve showing voltage-current characteristics of the fuel cell 11 (FIG. 1). A curve 41 showing the voltage-current characteristic of the fuel cell 11 is a normal PEM.
As in the case of the fuel cell, the voltage decreases as the voltage increases as the current increases as a whole. Although the slope is gentle up to the current value A, the slope becomes steep with the point B corresponding to the current value A as an inflection point. The power characteristic of the fuel cell 11 corresponding to this is shown by a curve 45.

From this, it can be seen that it is efficient to use the fuel cell 11 in a range up to the vicinity of the current value A. As described above, the fuel cell 11
Is a power supply having almost zero output impedance.

On the other hand, the curve 43 showing the voltage-current characteristic of the battery 12 is a straight line with the voltage decreasing as the current increases as a whole, like a normal battery. Does not change at all. Moreover, the inclination angle is substantially equal to the inclination angle of the curve 41 up to the current value A.

Therefore, when the current to be supplied to the motor 14 via the inverter 13, that is, when the required current value is in the range up to the current value A, the current is supplied only from the fuel cell 11, and the required current value is It can be seen that in the range above and near the current value A, the current may be supplied from the battery 12 in addition to the current from the fuel cell 11. The open terminal voltage of the battery 12 is substantially equal to the terminal voltage of the fuel cell 11 at the point B on the curve 41 corresponding to the current value A. In the range up to the vicinity of A, no current is supplied from the battery 12.

However, when the output voltage of the battery 12 is boosted to the terminal voltage of the fuel cell 11 by the booster circuit, current is also supplied from the battery 12 positively.

Since the terminal voltage of the fuel cell 11 at the point B on the curve 41 where the required current value corresponds to the current value A is substantially equal to the open voltage of the battery 12, the current value A is slightly reduced. Battery 1 in the range beyond
Current is also supplied from 2. However, the battery 12
As shown in the curve 43 showing the voltage-current characteristics of the battery 12, the terminal voltage of the battery 12 is reduced when the current is supplied from the battery 12, so that the current value does not increase so much. .

However, the battery 1
2 is increased to the terminal voltage of the fuel cell 11 and the currents from the fuel cell 11 and the battery 12 are combined, a curve 42 showing a voltage-current characteristic is obtained. The voltage becomes a downward-sloping linear shape in which the voltage decreases as the voltage increases. The corresponding power characteristic is shown by curve 44.

Here, for example, the power to be supplied to the motor 14 via the inverter 13, that is, the required power is C
, This corresponds to a point D on the curve 44 indicating the power characteristic. Then, it can be seen that the point on the curve 42 indicating the voltage-current characteristic corresponding to the point D is E, and the current value corresponding to this is F. Therefore, in this case, it can be seen that the fuel cell 11 supplies a current of the current value A, and the battery 12 supplies a current of the current value (FA).

In the present embodiment, the characteristics of the fuel cell 11 and the battery 12 as shown in FIG. 4 are stored in the storage means of the hybrid circuit electronic control unit 20 in advance. The required power to be supplied to the motor 14 is calculated by the calculating means based on signals such as the vehicle speed and the accelerator opening transmitted from the vehicle electronic control unit 21, and the required current corresponding to the required power is calculated. A value is found based on the characteristics of the fuel cell 11 and the battery 12 as shown in FIG.

On the other hand, as will be described later, the running mode of the vehicle is determined, the generation of a regenerative current is predicted based on the running mode, and the fuel is supplied so that the battery 12 can be charged with the regenerative current. The output currents from the battery 11 and the battery 12 are controlled.
The output current is controlled based on the characteristics of the fuel cell 11 and the battery 12 as shown in FIG.

Here, the basic operation of the fuel cell circuit 10 based on the characteristics of the fuel cell 11 and the battery 12 as shown in FIG. 4 will be described.

First, the case where the required current value is equal to or less than the current value A in FIG. 4, and when the current is supplied only from the fuel cell 11, the IGBT 15a in the battery charge control circuit 15 and the battery discharge control circuit 16 , 1
6a is turned off.

In this case, hydrogen as fuel and oxygen or air as oxidant are always sufficiently supplied to the fuel cell 11, so that even if the required current value fluctuates, A current having a value corresponding to the required current value is automatically supplied from the battery 11. Therefore, there is no need to control the output current of the fuel cell 11 according to the change in the value of the required current. The value of the current supplied from the fuel cell 11 is measured by a current sensor 18 and the current value A
The hybrid circuit electronic control unit 20 constantly detects whether or not the following is true. Also, the voltage is constantly detected by the hybrid circuit electronic control unit 20.

Next, when the required current value or the current value measured by the current sensor 18 is equal to or greater than the current value A, for example, when the current value is F in FIG. IGBT in discharge control circuit 16
If the switch 16a is kept off, the current value from the battery 12 does not increase so much as described above.

Here, in order to actively supply current from the battery 12 as well, the hybrid circuit electronic control unit 20 needs to be connected to the battery discharge control circuit 1.
6, the IGBT 16a is set to a predetermined cycle (for example, 20
(On the order of [kHz]). When the IGBT 16a is turned on, the DC current output from the battery 12
When the IGBT 16a is turned off, a voltage corresponding to the energy stored in the reactor 17 is added to the output voltage of the battery 12, and the total is added to the output voltage of the fuel cell 11. Is almost equal to This corresponds to the point G on the curve 43 in FIG. 4 having been shifted upward to the point E on the curve 42.

And a voltage value corresponding to the point E;
A current having a current value (FA) is supplied from the battery 12 to the motor 14 via the inverter 13. In addition,
The value of the current supplied from the battery 12 is measured by a current sensor 18 and checked by the hybrid circuit electronic control unit 20.

Next, the SOC (sta) of the battery 12
The basic operation of the fuel cell circuit 10 when the battery 12 is charged will be described because the te of charge (remaining capacity) has decreased.

First, during deceleration operation of the vehicle, the motor 14
Functions as a generator and generates an AC regenerative current, which is subsequently converted by the inverter 13 into a DC regenerative current. At this time, the hybrid circuit electronic control unit 20 turns on the IGBT 15a in the battery charge control circuit 15 by a switching signal. Therefore, the DC regenerative current is supplied to the battery 12 through the IGBT 15a, so that the battery 12 is charged.

The value of the regenerative current is determined by the current sensor 1
8 and is constantly checked by the hybrid circuit electronic control unit 20. Also, the voltage is constantly checked by the hybrid circuit electronic control unit 20. And the battery 12
Is sufficiently turned off, the IGBT 15a is turned off. Further, when the value of the regenerative current is excessive, the IGBT 15a is turned on / off by a switching signal of a predetermined cycle to control the value of the current flowing through the IGBT 15a.

Therefore, when the SOC of the battery 12 is sufficiently high, the battery 12 is charged or a large current is supplied to the battery 1.
Since the battery 12 is not supplied to the battery 12, the battery 12 is not destroyed by being overcharged.

In the case where the SOC of the battery 12 is lowered and charging is required, and when the regenerative current is not generated, the battery 12 is charged by supplying current from the fuel cell 11. In this case, the hybrid circuit electronic control unit 20 is connected to the battery charge control circuit 15.
Is turned on by the switching signal, the DC regenerative current is supplied to the battery 12 through the IGBT 15a. Therefore, the battery 12 is charged.

The value of the current from the fuel cell 11 and the value of the current supplied to the battery 12 are measured by a current sensor 18 and are constantly checked by the hybrid circuit electronic control unit 20. Also, regarding the voltage, the hybrid circuit electronic control unit 2
Always checked by 0. When the SOC of the battery 12 is sufficiently increased, the fuel cell 11
When the value of the current supplied from is equal to the current value A,
When the value of the required current supplied to the motor 14 via the inverter 13 is large, the IGBT 15a
Is turned off. If the value of the current supplied to the battery 12 is excessive, the IGBT 15a is turned on / off by a switching signal of a predetermined cycle to control the value of the current flowing through the IGBT 15a.

Therefore, the battery 12 is charged when the SOC of the battery 12 is sufficiently high, or a large current is supplied to the battery 1.
Since the battery 12 is not supplied to the battery 12, the battery 12 is not destroyed by being overcharged. Further, there is no possibility that an excessive load is applied to the fuel cell 11 or the fuel cell 11 cannot cope with the required current.

Next, an example of the relationship between the operation of the fuel cell circuit 10 described above and the traveling mode as the traveling state of the vehicle will be described.

FIG. 5 is a diagram showing an example of the relationship between the operation of the fuel cell circuit 10 and the running mode in the embodiment of the present invention. In FIG. 5, the horizontal axis represents the vehicle load, and the vertical axis represents the output.

In FIG. 5, reference numeral 51 denotes a straight line indicating the relationship between the load of the vehicle and the output of the fuel cell 11 (FIG. 1) and the battery 12, ie, the magnitude of the required current when the load of the vehicle is in the positive range. Is a straight line indicating the relationship between the load of the vehicle and the output of the motor 14, that is, the magnitude of the regenerative current, in the negative range.

Here, the load of the vehicle is lowest when the vehicle is in the low-load driving mode in which the vehicle travels in an urban area or the like. The load is high-speed cruising on a highway, high-load driving on an uphill, or high-speed driving. It becomes higher in the order of the maximum load operation when traveling on an uphill road or the like. Then, the value of the required current increases in proportion to the load of the vehicle.

On the other hand, when the vehicle is traveling on a downhill or the like and the motor 14 functions as a generator to generate a regenerative current in a regenerative mode, the vehicle decelerates and the vehicle load is reduced. Is negative, and the value of the regenerative current is proportional to the absolute value of the load on the vehicle.

In the region 53 where the vehicle load is negative, the hybrid circuit electronic control unit 2
0 is the IGBT 15 in the battery charge control circuit 15.
Since a is turned on by the switching signal, the regenerative current is supplied to the battery 12 through the IGBT 15a. Therefore, the battery 12 is charged.

Next, in a region 54 from the vehicle load of 0 to the boundary J corresponding to the current value A in FIG. 4, an inverter in which a current having a value corresponding to the required current is automatically supplied from the fuel cell 11 The motor 13 is supplied to the motor 14 via the motor 13.

In the region 54, when the SOC of the battery 12 is low, the hybrid circuit electronic control unit 20 sets the battery charge control circuit 15
By turning on the IGBT 15a for an appropriate time, the current is supplied from the fuel cell 11 to charge the battery 12.

On the other hand, when the SOC of the battery 12 is high and there is no room for receiving the regenerative current, it is desirable to slightly discharge the battery 12 to create a room for receiving the regenerative current. So
The hybrid circuit electronic control unit 20 turns on and off the IGBT 16a in the battery discharge control circuit 16 by a switching signal of a predetermined period, and the current from the battery 12
To be supplied. Thereby, the fuel cell 11
Since the current to be supplied from the fuel cell 11 can be reduced, the load on the fuel cell 11 can be reduced, and the fuel consumption can be suppressed. The SOC of the battery 12 is 8
It is desirable that the value is about 0 [%].

Finally, in the regions 55 and 56 where the load of the vehicle exceeds the boundary J, since the required current value exceeds the current value A in FIG. 4, the hybrid circuit electronic control unit 20 performs the battery discharge control. The IGBT 16a in the circuit 16 is turned on / off by a switching signal of a predetermined cycle, and in addition to the current of the current value A from the fuel cell 11, a current exceeding the current value A from the battery 12 is supplied to the motor via the inverter 13 via the inverter 13. 14. In FIG. 5, a region 55 indicates a range of an output by the current from the fuel cell 11, and a region 56 indicates a range of an output by a current from the battery 12.

Next, a control method of the fuel cell circuit 10 corresponding to various running modes of the vehicle according to the present embodiment will be described in detail.

FIG. 6 is a diagram showing the basic concept of the control method of the fuel cell circuit in the embodiment of the present invention, and FIG. 7 is a diagram showing the SOC value of the battery in various running modes in the embodiment of the present invention. FIG. 8 is a diagram showing output ranges of the fuel cell and the battery in various driving modes according to the embodiment of the present invention. FIG. 9 is a flowchart showing a control operation of the fuel cell circuit according to the embodiment of the present invention.
0 is a first flowchart showing the operation of the process outside the SOC reference range in the embodiment of the present invention, FIG. 11 is a second flowchart showing the operation of the process outside the SOC reference range in the embodiment of the present invention, and FIG. It is a 3rd flowchart which shows operation | movement of the process outside an SOC reference range in embodiment of this invention.

In the present embodiment, the fuel cell circuit 10 (FIG. 1) is controlled so that the regenerative current can be used as much as possible without wasting. That is,
The regenerative current is energy that is generated by making the motor 14 function as a brake when the vehicle needs to be braked, such as when traveling on a downhill, etc. Fuel cell 1
One fuel can be saved.

Since the regenerative current is not generated constantly, it is necessary to charge the battery 12 in order to use the regenerative current. Therefore, battery 1
When the SOC of No. 2 is high, it is necessary to lower the SOC to some extent to leave room for charging. On the other hand, when the vehicle travels in the regions 55 and 56 where the load of the vehicle exceeds the boundary J in FIG. 5, it is necessary to output the current from the battery 12. It is impossible to cope with a case in which there is a series of.

Therefore, the generation of the regenerative current is predicted based on the running mode of the vehicle, and the SO of the battery 12 is charged so that the regenerative current can be charged in the battery 12.
C needs to be controlled.

Next, the running mode of the vehicle and the fuel cell (F
The basic concept of C) 11 and the output of the battery (BT) 12 will be described.

FIG. 6 shows a predetermined time (5
20 is a table for determining the driving mode of the vehicle according to which area the vehicle has been driven in a large number of times during a period of about 20 minutes. Here, 65 is the motor 1 when traveling at a constant speed on a flat road with a gradient of 0 degrees, that is, when traveling at a constant speed.
4 is a curve showing the relationship between the output of No. 4 and the speed of the vehicle.

First, in the area 61, the vehicle speed is low and the motor 14
Is higher than the constant speed traveling, it can be said that it is a traveling mode in which start and stop of a city area or the like are repeated, that is, a city area mode. Therefore, it is predicted that there will be many deceleration operations that apply braking to the vehicle, and regenerative current will frequently occur.
By supplying current mainly from the battery 12,
The SOC of the battery 12 is relatively low, for example, 60%
To the extent that the battery 1
2 can be charged.

In the area 62, the vehicle speed is high and the motor 1
Since the output of No. 4 is higher than the constant speed traveling, it can be said that the traveling mode cruises a suburb or an expressway, ie, the high speed mode. Therefore, there is little deceleration operation for applying a brake to the vehicle, and regenerative current is not generated so much.
It is predicted that the required current may not be able to be satisfied only with the current from the battery 12.
C is kept high, for example, about 75%, so that the current can always be supplied from the battery 12 when necessary.

Next, since the output of the motor 14 in the region 63 is higher than that at the constant speed traveling, it can be said that the traveling mode is a downhill on a mountain road, that is, a downhill mode. Therefore, although it is required to output the signal on the occasional uphill, it is predicted that a high regenerative current will be generated.
2 is maintained at a low level, for example, about 50%, so that the battery 12 can be fully charged with the regenerative current.

Finally, the region 64 is a region where the vehicle speed is low.
Since the output of the motor 14 is high, it can be said that the driving mode is an uphill running on a mountain road, that is, a mountain road mode.
Therefore, although a regenerative current is generated on a downhill from time to time, it is predicted that the current from the fuel cell 11 alone cannot satisfy the required current.
Is maintained relatively high, for example, about 70%, so that the current can be supplied from the battery 12 as well.

In the present embodiment, a reference value of the SOC of battery 12 is set according to the determined driving mode. Then, the operation of the fuel cell circuit 10 is controlled so that the measured value of the SOC of the battery 12 falls within the range of the reference value.

First, the hybrid circuit electronic control unit 20 determines the vehicle speed, the accelerator opening θ (proportional to the torque to be generated by the motor 14), the current values supplied from the fuel cell 11 and the battery 12 for the past 5 to 20 minutes, It is determined based on the change of the numerical value such as the SOC of the battery 12 or the duration thereof whether the running mode of the vehicle up to the present time is the high-speed mode, the mountain road mode, the mountain road mode, or the city area mode. The fuel cell circuit 10 predicts that the determined driving mode will be continued for 5 to 20 minutes from the present time.
Control the operation of.

Here, the time for determining the traveling mode can be set as appropriate, and may be, for example, about 1 to 5 minutes in the past or about 20 to 40 minutes in the past. In addition, the time during which the determined traveling mode is predicted to be continued can be set as appropriate, and may be, for example, 1 to 5 minutes from the current time or 20 to 40 minutes from the current time.

The above numerical values are measured directly by the hybrid circuit electronic control unit 20 or by other control devices such as the vehicle electronic control unit 21.

Further, when the vehicle is provided with a vehicle position detecting device, for example, a navigation device, the current running mode of the vehicle can be determined by the navigation device. The unit 20 sets the current vehicle traveling mode to the high-speed mode based on the information from the navigation device,
It may be determined whether the mode is the mountain road mode, the mountain road mode, or the city area mode.

Subsequently, as shown in FIG. 7, the hybrid circuit electronic control unit 20 sets a reference value of the SOC of the battery 12 according to the determined current traveling mode of the vehicle.

First, in the case of the high-speed mode, for example,
A range of ± 10 [%] around 75 [%], that is, 65 to 85 [%] is set as the SOC reference value. In the case of the mountain road mode, for example, 60
If 80% is in the mountain trail mode, for example,
In the case of the city area mode, 40 to 60% is set as the SOC reference value, for example, 50 to 70%, respectively.

Then, the current SOC of the battery 12
Is within the range of the reference value, the operation of the fuel cell circuit 10 is controlled as shown in FIG.

In the high speed mode shown in FIG. 8A, when the vehicle speed is low, the current is supplied from the fuel cell 11 and the current is not supplied from the battery 12, so that the battery charge control circuit 15 and the battery The IGBTs 15a and 16a in the discharge control circuit 16 are turned off. When the vehicle speed is high and the required power exceeds the supply capacity of the fuel cell 11, current is also supplied from the battery 12. Also at this time, the IGBT 1 in the battery charge control circuit 15 and the battery discharge control circuit 16
5a and 16a are turned off.

Next, in the on-street mode shown in FIG. 8B, when the vehicle speed is low and the accelerator opening θ is small,
Since the current is supplied from the battery 12 and the current is not supplied from the fuel cell 11, the IGBT 15a in the battery charge control circuit 15 is turned off, and the IGBT 16a in the battery discharge control circuit 16 is turned on and off by a switching signal of a predetermined cycle. I do. As a result, the output voltage of the battery 12 is boosted to be equal to or higher than the output voltage of the fuel cell 11, so that no current is supplied from the fuel cell 11.

When the vehicle speed is low but the accelerator opening θ is large, the operation is the same as when the vehicle speed in the high-speed mode is low, and when the vehicle speed is high, the operation is the same as when the vehicle speed in the high-speed mode is high. is there.

Next, in the downhill mode shown in FIG. 8C, the numerical ranges of the vehicle speed and the accelerator opening θ are different, but the others are the same as in the uphill mode.

Finally, in the city area mode shown in FIG. 8D, when the vehicle speed is low and the accelerator opening θ is large, the current is supplied from the battery 12 and the current is not supplied from the fuel cell 11. The difference is only in the point, but the other points are the same as those in the above-mentioned mountain road mode or the mountain road lower mode.

Next, the operation of the fuel cell circuit 10 when the current SOC of the battery 12 is out of the range of the reference value will be described.

First, when the SOC of the battery 12 has not reached the lower limit of the range of the reference value, the battery 12 needs to be charged. That is, the value of the charging current is set.

If the sum of the charging current and the required current does not exceed the maximum supply current value of the fuel cell 11 (current value A in FIG. 4), a part of the current supplied from the fuel cell 11 Are used for charging the battery 12. In this case, the IGBT 15a in the battery charge control circuit 15 is turned on.

The current value from the fuel cell 11 and the current value of the charging current supplied to the battery 12 are measured by the current sensor 18 and are always detected by the hybrid circuit electronic control unit 20. Also,
The voltage is also constantly detected by the hybrid circuit electronic control unit 20. And the battery 1
2 is increased to the reference value range, when the value of the current supplied from the fuel cell 11 reaches the maximum supply current value, and when the SOC is supplied to the motor 14 via the inverter 13. When the required current value is large, the IGBT 15a is turned off. Further, when the value of the current supplied to the battery 12 is excessive, the IGBT 15a is turned on / off by a switching signal of a predetermined cycle to control the value of the current flowing through the IGBT 15a.

On the other hand, since the fuel cell 11 is not controlled at all, a current obtained by adding the charging current and the required current is supplied from the fuel cell 11.

Next, when the sum of the charging current and the required current exceeds the maximum supply current value of the fuel cell 11,
It is determined whether or not the required current exceeds the maximum supply current value of the fuel cell 11.

If the battery charge does not exceed the limit, the charging of the battery 12 is stopped. In this case, the IGBT 15a in the battery charge control circuit 15 is turned off. Since the fuel cell 11 is not controlled at all, a current equal to the required current is supplied from the fuel cell 11 to the motor 14 via the inverter 13.

Next, when the required current exceeds the maximum supply current value of the fuel cell 11, the charging of the battery 12 is stopped, and the current is also supplied from the battery 12 to the motor 14. To do. In this case, the IGBT 15a in the battery charge control circuit 15 is turned off, and the IGBT 16a in the battery discharge control circuit 16 is turned on / off by a switching signal of a predetermined cycle to boost the output voltage of the battery 12.

The current value from the fuel cell 11 and the current value supplied from the battery 12 are measured by a current sensor 18 and are constantly checked by the hybrid circuit electronic control unit 20. Also, regarding the voltage, the hybrid circuit electronic control unit 20 is used.
Always checked by Then, the on / off ratio (duty ratio) of the IGBT 16 a in the battery discharge control circuit 16 is controlled to control the value of the current output from the battery 12.

On the other hand, since the fuel cell 11 is not controlled at all, a current obtained by subtracting the current from the battery 12 from the required current is supplied from the fuel cell 11.

Next, when the SOC of the battery 12 exceeds the upper limit of the range of the reference value, it is determined whether or not the required current exceeds the maximum supply current value of the battery 12.

If the current is not exceeded, the current is supplied from the battery 12 so that the current is not supplied from the fuel cell 11. In this case, the IGBT 15a in the battery charge control circuit 15 is turned off, and the IGBT 15 in the battery discharge control circuit 16 is turned off.
The output voltage of the battery 12 is boosted by turning on / off the switch 16a by a switching signal of a predetermined cycle.

The value of the current supplied from the battery 12 is measured by the current sensor 18 and is constantly detected by the hybrid circuit electronic control unit 20. Also, the voltage is constantly detected by the hybrid circuit electronic control unit 20.

On the other hand, although the fuel cell 11 is not controlled at all, since the boosted output voltage of the battery 12 is higher than the open terminal voltage of the fuel cell 11, the fuel cell 1
No current is output from 1.

Next, when the required current exceeds the maximum supply current value of the battery 12, the current value supplied from the battery 12 is set. Then, current is supplied from the fuel cell 11 and the battery 12 to the motor 14. In this case, the IGBT 15a in the battery charge control circuit 15 is turned off, and the IGBT 16a in the battery discharge control circuit 16 is turned on / off by a switching signal of a predetermined cycle to boost the output voltage of the battery 12.

The value of the current from the fuel cell 11 and the value of the current supplied from the battery 12 are measured by a current sensor 18 and are always detected by the hybrid circuit electronic control unit 20. Also, the voltage is constantly detected by the hybrid circuit electronic control unit 20. Then, the value of the current output from the battery 12 is controlled by controlling the on / off ratio of the IGBT 16 a in the battery discharge control circuit 16.

On the other hand, since the fuel cell 11 is not controlled at all, a current obtained by subtracting the current from the battery 12 from the required current is supplied from the fuel cell 11.

As described above, in the present embodiment, the reference value of the SOC of the battery 12 is set according to the determined driving mode so that the measured value of the SOC of the battery 12 falls within the range of the reference value. Next, the operation of the fuel cell circuit 10 is controlled. Therefore, there is adequate room for charging the regenerative current in the battery 12, so that the regenerative current, which is energy generated as a by-product, is not wasted.
The fuel cell 11 can be used as much as possible, and the fuel of the fuel cell 11 can be saved. In addition, since it is not necessary to increase the capacity of the battery 12 more than necessary, the weight and size of the vehicle accommodating the battery 12 can be reduced,
Cost can be reduced.

Further, without special control, the fuel cell 1
1 supplies the appropriate current. Therefore, even when the required current exceeds the maximum supply current value of the fuel cell 11, the insufficient current is supplied from the battery 12, so that the running of the vehicle is not hindered.

Further, even if the measured value of the SOC of the battery 12 does not fall within the range of the reference value, the fuel cell 1
1 and the distribution of the current output from the battery 12 can be appropriately controlled, so that there is no hindrance to the running of the vehicle and the battery 12 does not run out.

Next, the main flowchart of the control operation of the fuel cell circuit will be described. Step S1 The vehicle speed is detected. Step S2: Changes in vehicle speed are stored. Step S3: A torque to be generated by the motor 14 is detected. Step S4: The value of the current supplied from the battery 12 is detected. Step S5: The SOC of the battery 12 is calculated. Step S6: The value of the current supplied from the fuel cell 11 is detected. Step S7: The running mode of the vehicle is determined. Step S8: The battery 12 according to the traveling mode of the vehicle
The SOC reference value is set. Step S9: It is determined whether or not the detected SOC of the battery 12 is within the range of the reference value. If it is within the range, the process proceeds to step S11.
Proceed to. Step S10: The process outside the SOC reference range is performed. Step S11: The accelerator opening θ is detected. Step S12 The outputs of the fuel cell 11 and the battery 12 are controlled according to FIGS.

Next, a flowchart of a subroutine for processing outside the SOC reference range in step S10 will be described. Step S10-1: It is determined whether or not the detected SOC of the battery 12 is equal to or lower than the lower limit of the range of the reference value. In the following cases, the process proceeds to step S10-2, and if not, that is, if the value exceeds the upper limit of the reference value range, the process proceeds to step S1.
Go to 0-7. Step S10-2: Set the current value of the charging current. Step S10-3: It is determined whether or not the sum of the charging current and the required current is less than the maximum supply current value of the fuel cell 11. If it is less, the process proceeds to step S10-4, and if not, the process proceeds to step S10-19. Step S10-4 A part of the current supplied from the fuel cell 11 is used for charging the battery 12. Step S10-5: IG of the battery charge control circuit 15
Turn on the BT 15a. Step S10-6 The fuel cell 11 is not controlled at all,
A current obtained by adding the charging current and the required current is supplied, and the process ends. Step S10-7: It is determined whether the required current is less than the maximum supply current value of the battery 12. If it is less than, the process proceeds to step S10-8.
Proceed to. Step S10-8: Supply current from the battery 12,
No current is supplied from the fuel cell 11. Step S10-9: IG of the battery discharge control circuit 16
The BT 16a is turned on / off by a switching signal of a predetermined cycle, and the output voltage of the battery 12 is boosted. Step S10-10 The fuel cell 11 is not controlled at all, and the process ends without supplying current. Step S10-11 The current value of the current supplied from the battery 12 is set. Step S10-12 In addition to the current from the battery 12, the current from the fuel cell 11 is also supplied to the motor 14. Step S10-13 The current value of the current supplied from the battery 12 to the motor 14 is calculated. Step S10-14: I of the battery discharge control circuit 16
The GBT 16a is turned on / off by a switching signal of a predetermined cycle, and the output voltage of the battery 12 is boosted. Step S10-15 The fuel cell 11 is not controlled at all, supplies a current having a value obtained by subtracting the current from the battery 12 from the required current, and ends the processing. Step S10-16: It is determined whether the required current is less than the maximum supply current value of the fuel cell 11. If the value is less than the value, the process proceeds to step S10-17.
Go to 20. Step S10-17 Charging of the battery 12 is stopped. Step S10-18: I of the battery charge control circuit 15
Turn off the GBT 15a. Step S10-19 The fuel cell 11 is not controlled at all, supplies the required current, and ends the processing. Step S10-20: The charging of the battery 12 is stopped. Step S10-21 In addition to the current from the fuel cell 11, the current from the battery 12 is also supplied to the motor 14. Step S10-22 The current value supplied from the battery 12 to the motor 14 is calculated. Step S10-23: I of the battery discharge control circuit 16
The GBT 16a is turned on / off by a switching signal of a predetermined cycle, and the output voltage of the battery 12 is boosted. Step S10-24 The fuel cell 11 is not controlled at all, supplies the required current, and ends the processing.

The present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0129]

As described above in detail, according to the present invention, in a fuel cell circuit, a fuel cell, a load connected to an output terminal of the fuel cell, and the fuel In a fuel cell circuit including a battery and a secondary battery circuit connected in parallel, the secondary battery circuit includes a secondary battery having a lower voltage than the fuel cell as a reference voltage, and an output voltage of the secondary battery. A booster circuit for boosting and supplying the load to the load; and a charging circuit for charging the secondary battery with a current output from the fuel cell.

In this case, even if the required current required by the load exceeds the maximum supply current value of the fuel cell,
Insufficient current is supplied from the secondary battery. In addition, since the secondary battery is appropriately charged by the regenerative current or the like, the secondary battery does not rise.

In another fuel cell circuit, the fuel cell circuit includes a fuel cell connected to a load, and a secondary cell circuit connected in parallel to the fuel cell and the load. The secondary battery circuit includes a charging switching element and a boosting switching element connected in series to each other, a secondary battery connected in parallel to the boosting switching element via a reactor, the load or the secondary battery. A diode element arranged to prevent current from the next cell from being supplied to the fuel cell.

In this case, while having a simple circuit configuration,
Since the SOC of the secondary battery can be appropriately controlled,
The regenerative current can be utilized as much as possible without wasting, and fuel for the fuel cell can be saved. Moreover, there is no need to increase the capacity of the secondary battery more than necessary. Further, a current corresponding to the required current is appropriately supplied from the fuel cell and the battery. Further, since the secondary battery is appropriately charged by the regenerative current or the like, the secondary battery does not run out.

Further, in still another fuel cell circuit,
Further, the load is a drive control device of a drive motor that drives the vehicle.

In this case, while having a simple circuit configuration,
Since the current corresponding to the required current is appropriately supplied from the fuel cell and the secondary battery, the running of the vehicle is not hindered.

Further, in still another fuel cell circuit,
Further, the load is an inverter device of a drive motor for driving the vehicle.

In this case, the distribution of the current output from the fuel cell and the secondary battery can be appropriately controlled.
There is no hindrance to the running of the vehicle, and the secondary battery does not run out.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a fuel cell circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional fuel cell circuit.

FIG. 3 is a diagram showing characteristics of a fuel cell and a battery in a conventional vehicle hybrid circuit.

FIG. 4 is a diagram showing characteristics of the fuel cell and the battery according to the embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of a relationship between an operation of the fuel cell circuit and a driving mode in the embodiment of the present invention.

FIG. 6 is a diagram showing a basic concept of a control method of a fuel cell circuit in an embodiment of the present invention.

FIG. 7 is a diagram showing SOC values of a battery in various traveling modes according to the embodiment of the present invention.

FIG. 8 is a diagram showing output ranges of a fuel cell and a battery in various traveling modes according to the embodiment of the present invention.

FIG. 9 is a flowchart showing a control operation of the fuel cell circuit in the embodiment of the present invention.

FIG. 10 is a first flowchart illustrating an operation of an SOC out-of-reference range process according to the embodiment of the present invention.

FIG. 11 is a first flowchart showing an operation of an SOC out-of-range processing according to the embodiment of the present invention.

FIG. 12 is a first flowchart illustrating an operation of an out-of-SOC reference range process according to the embodiment of the present invention.

[Explanation of symbols]

 10 Fuel cell circuit 11 Fuel cell 12 Battery 17 Reactor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/00 H02J 7/00 P 7/34 7/34 C (72) Inventor Akira Suzuki Anjo-shi, Aichi 10 Takane Fujiimachi Inside Aisin AW Co., Ltd. (72) Inventor Yoshihiko Minatani 10 Takane Fujiimachi Aki, Aichi Prefecture Aisin AW Co., Ltd. (72) Inventor Yutaka Hotta Anjo City, Aichi Prefecture 10 Takane Fujiimachi Inside Aisin AW Co., Ltd. (72) Inventor Yoshihiro Nakajima 10 Takane Fujiimachi Aki, Aichi Prefecture Aisin AW Co., Ltd. F-term (reference) 5G003 AA05 BA01 CA14 CC02 DA07 DA16 FA06 GB06 5H027 AA03 AA04 AA05 AA06 DD00 DD03 MM26 5H030 AA01 AA03 AA04 AS08 BB01 BB22 BB26 DD04 DD20 5H420 BB14 CC03 CC06 DD03 DD05 EA10 EB39

Claims (4)

[Claims] 1. A fuel cell circuit comprising: a fuel cell; a load connected to an output terminal of the fuel cell; and a secondary cell circuit connected to the load in parallel with the fuel cell. The secondary battery circuit includes a secondary battery that uses a voltage lower than the fuel cell as a reference voltage, a booster circuit that boosts an output voltage of the secondary battery and supplies the boosted output voltage to the load, A charging circuit for charging the secondary battery. 2. A fuel cell circuit comprising: a fuel cell connected to a load; and a secondary cell circuit connected in parallel to the fuel cell and the load, wherein the secondary cell circuit comprises:
A charging switching element and a boosting switching element connected in series to each other, a secondary battery connected in parallel to the boosting switching element via a reactor, and a current from the load or the secondary battery. And a diode element disposed so as not to be supplied to the fuel cell. 3. The fuel cell circuit according to claim 1, wherein the load is a drive control device of a drive motor that drives a vehicle. 4. The fuel cell circuit according to claim 1, wherein the load is an inverter device of a drive motor for driving a vehicle.