JP2000228226A - Charging device for nickel-based battery for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device for a nickel-based battery for an electric automobile that can correctly perform the full-charge determination of the nickel-based battery even when there is a remarkable temperature difference between indoor and outdoor locations. SOLUTION: This charging device detects the temperature of nickel-based batteries 4 and the temperature of the outside air before charging the nickel- based batteries 4, keeping the start of charging on standby until both temperatures becomes nearly equal to each other, and charging of the nickel- based batteries 4 is first started when the temperature of the nickel-based batteries 4 becomes nearly equal to the temperature of the outside air, so that the full charge determination of the nickel-based batteries 4 can correctly be performed without being affected by the outside air temperature by using a characteristic of temperature rise occurring at the terminating period of the charging even if the charging of the nickel-based batteries 4 is carried out with a charger 12 located indoor immediately after running at a cold district where there is a remarkable temperature difference between indoor and outdoor locations.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle charger for charging a nickel-based battery mounted on an electric vehicle.

[0002]

2. Description of the Related Art In an electric vehicle (EV), a battery having a high energy density is required in order to obtain power required for traveling from an electric motor. In addition, the battery is required to have a long life and cost.

[0003] In response to such demands, in electric vehicles,
As a battery suitable for an electric vehicle, a Ni-hydrogen battery using a nickel member for a positive electrode and a hydrogen storage alloy for a negative electrode is often used.

[0004] Similar to other batteries (Japanese Patent Application Laid-Open No. 9-46917), a Ni-hydrogen battery is charged with a constant current over a period of time (about 8H) using a charger. However, unlike other batteries, the Ni-hydrogen battery has a characteristic that the temperature rises at the end of charging as shown in the diagram of FIG. This is because electrolysis of water occurs due to the reaction between the electrolyte and the electrode plate at the end of charging of the Ni-hydrogen battery, and the heat generated by the electrolysis causes an increase in temperature.

[0005] The Ni-hydrogen battery is judged to be fully charged by reading the point where the temperature rises.

However, the temperature rise at the end of charging of a Ni-hydrogen battery is a small temperature change at a moment of 0.3 ° C. to 0.5 ° C. per minute.
-It is difficult to read because the hydrogen battery itself tends to warm up.

As a countermeasure, a structure is adopted in which the Ni-hydrogen battery is cooled by the outside air using an outside air intake fan.
-The charge management of charging the hydrogen battery is performed.

As a result, heat due to charging is removed to the outside, so that the temperature at the end of charging of the original Ni-hydrogen battery rises,
That is, a full charge determination can be made, and the charger is stopped at a favorable time according to the full charge determination.

[0009]

By the way, in a cold region, a charger is installed indoors, for example, in a garage whose entire periphery is surrounded by a wall, and after traveling in the cold region, the electric vehicle is immediately turned on. May be charged.

However, if the Ni-hydrogen battery is charged in such an environment where there is a considerable temperature difference indoors and outdoors, an error occurs in the determination of the full charge of the Ni-hydrogen battery.

For example, an electric vehicle that has finished traveling in a cold region of -20 ° C. enters, for example, a heated indoor garage of about 10 ° C., and immediately performs charging by the charger while performing the charge management described above. Let's say it started.

[0012] At this time, the surface temperature of the Ni-hydrogen battery of the electric vehicle which has traveled outdoors below minus is several degrees Celsius, but the outside air blown from the outside air intake fan to the Ni-hydrogen battery is in the indoor garage. The warm air inside warms the cooled Ni-hydrogen battery.

[0013] Then, the battery surface temperature rises only by blowing outside air, even though the battery is not yet fully charged, so that the charger erroneously determines that this temperature rise is the temperature rise at the end of charging and starts charging. Stop it. In this case, accurate full charge determination cannot be performed.

Therefore, charging outdoors is conceivable, but charging work under low outside temperature in a cold region is difficult. Moreover,
There is a problem that the charging efficiency of the battery itself is reduced, and there is a demand for a technology that can perform satisfactory full charging indoors even when there is a temperature difference between indoor and outdoor.

The present invention has been made in view of the above circumstances. It is an object of the present invention to provide a battery capable of accurately determining whether a nickel-based battery is fully charged, even when the battery has a considerable temperature difference indoors and outdoors. An object of the present invention is to provide a charging device for a nickel-based battery for an automobile.

[0016]

According to a first aspect of the present invention, there is provided a charging device, wherein a temperature difference between a temperature of a nickel-based battery and a temperature of an outside air temperature is determined before charging the nickel-based battery. When the value is within the range, the nickel-based battery is started to be charged until the temperature rise at the end of charging is detected, and the nickel-based battery is not charged until the temperature of the nickel-based battery becomes equal to the temperature of the outside air. Charging started.

[0017] Thus, even if the nickel-based battery is charged by a charger indoors immediately after traveling in a cold region where there is a temperature difference between indoor and outdoor, the battery temperature rises due to the outside air. Since it is suppressed, the full charge of the nickel-based battery can be accurately determined without being affected by the outside air temperature.

Therefore, even in charging where there is a considerable temperature difference indoors and outdoors, it is possible to determine whether the nickel-based battery is fully charged by utilizing the temperature rise at the end of charging.

According to the second aspect of the present invention, even when there is a considerable difference in temperature between indoor and outdoor, the charging device starts the charging of the nickel-based battery before charging the nickel-based battery. When the temperature difference exceeds a predetermined value, the outside air is blown to the nickel-based battery, so that the difference between the temperature of the nickel-based battery and the temperature of the outside air quickly falls.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on one embodiment shown in FIGS.

FIG. 1 (a) shows a schematic configuration of a nickel-based battery charger for an electric vehicle to which the present invention is applied. In the figure, reference numeral 1 denotes a box-shaped garage formed indoors in a cold region, for example. is there. Doorway 2 formed in front of garage 1
Has a garage structure which is opened and closed by a shutter 3 and is entirely surrounded by walls. In the garage 1, for example, a stationary charger 12 is installed.

In the garage 1, an electric vehicle 5 (EV) equipped with a nickel-based battery, for example, a Ni-hydrogen battery 4, is parked.

In the electric vehicle 5, for example, a Ni-hydrogen battery 4 is placed under the floor of a vehicle body 5a in a lateral direction and a depth direction (both in FIG. 1).
), A plurality of flat box-shaped battery trays 6 are arranged and an electric motor 8 for driving a front wheel 7 (running wheel) is incorporated on the front side of the vehicle body 5a. Each Ni-hydrogen battery 4 is controlled by a command signal corresponding to an accelerator pedal or the like output from a controller 9 (for example, a microcomputer) incorporated in the vehicle body 5a.
To drive the electric motor 8. The terminal 4a of each Ni-hydrogen battery 4 is connected in series via a cable 10 so that a high power supply voltage is secured, and a charging port 11 formed on the rear side of the electric motor 8, for example, the vehicle body 5a. [(Fig. 1
(Illustrated in (a)).

The charging connector 1 formed at the end of the cable 13 extending from the charger 12 with respect to the charging port 11
4 are connected (for example, by an inductive method). Note that a signal line 15 for receiving a charge start signal / charge stop signal is also inserted through the cable 13.

On the other hand, as shown in detail in FIG. 1B, a suction port 16 is formed in the upper part of the front wall of the battery tray 6. An exhaust port 17 is formed in a rear wall of the battery tray 6. In addition, each Ni-hydrogen battery 4 is provided inside the battery tray 6, specifically, between each battery 4 and the tray upper wall 6a.
There is formed an air passage 18 through which outside air can be distributed. The air passage 18 communicates between the suction port 16 and the exhaust port 17. In addition, the suction port 16 communicates with an outside air inlet 19 on the tray bottom wall 6b of the battery tray 6 which is stepped so as to face the suction port 16 at the front thereof. Can be captured. Further, for example, a plurality of outside air intake / suction fans 20 are attached near the exhaust port 17. This suction fan 2
The operation (suction) of 0 allows outside air to be blown into the battery tray 6. In addition, 21 is
4 shows a prevention plate disposed between the outside air inlet 17 and the suction port 16 for preventing foreign matter from entering.

After the Ni-hydrogen battery 4 in the battery tray 6, the surface of the case of each battery 4 placed at, for example, a point that is not easily affected by the outside air (for example, at the four corners or the center of the battery tray 6) A temperature sensor 22 is attached to each of them so that the surface temperature (corresponding to the battery temperature) of the Ni-hydrogen battery 4 can be detected. Further, an outside air temperature sensor 23 is provided between the outside air inlet 19 and the suction port 16, particularly at a point where there is no possibility of foreign matter such as snow and sand entering, and the temperature of the outside air taken into the battery tray 6 is provided. Can be detected.

The controller 9 includes these suction fans 2
0, the temperature sensor 22, and the outside air temperature sensor 23 are used to accurately determine whether the Ni-hydrogen battery 4 is fully charged.

That is, the controller 9 includes: The function of detecting the difference between the battery surface temperature of the temperature sensor 22 and the outside air temperature when the charging connector 14 of the charger 12 is connected.

2. A function for detecting whether or not the battery surface temperature is substantially equal to the outside air temperature based on the detection result.

3. When the battery surface temperature is substantially equal to the outside air temperature, the charger 12
A function to output a charge start command to the device and to operate the suction fan 20 to start charging.

4. When there is a temperature difference between the battery surface temperature and the outside air temperature, a charge prohibition signal is output from the charging port 11 to the charger 12 through the signal line 15 and the charge start command is issued until the battery surface temperature and the outside air temperature become substantially equal. Standby function to delay the output of

5. While the charging is prohibited, the suction fan 20 is operated to quickly eliminate the difference between the battery surface temperature and the outside air temperature.

6. A function of detecting a temperature rise at the end of charging from a change in battery surface temperature detected by the temperature sensor 22 during charging.

7. When this end-of-charge temperature rise is detected,
A function of stopping the suction fan 20 and outputting a charge stop command to the charger 12 from the charging port 11 through the signal line 15.

In any environment, regardless of the temperature difference between indoor and outdoor, it is possible to determine whether the Ni-hydrogen battery 4 is fully charged by focusing only on the temperature rise at the end of charging. is there.

FIG. 2 shows a flowchart of the detailed charge control.

The charging of the Ni-hydrogen battery will be described with reference to the flowchart of FIG.
It is assumed that the electric vehicle 5 which has finished traveling in the cold region enters the heated garage 1 (indoor) at about 10 ° C. and immediately charges the vehicle.

At this time, first, the charging port 11 of the electric vehicle 5 parked in the garage 1 is opened, and the charging connector 14 of the charger 12 installed in the garage 1 is connected to this.

Thus, both the charger 12, the Ni-hydrogen battery 4, and the controller 9 are connected through the charging port 11.

In response to the connection of the charging connector 14, the controller 9 reads the outside air temperature A from the outside air temperature sensor 23 and reads the battery surface temperature B from the temperature sensor 22 as shown in steps S2 and S3. .

Then, the process proceeds to step S4, and based on the deviation (A−B) between the outside air temperature A and the averaged battery surface temperature B of each Ni-hydrogen battery 4, whether the outside air temperature A and the battery surface temperature B have become equal. Is determined. Note that the battery surface temperature B was Ni-
Since there is variation depending on the location in the battery tray 6 where the hydrogen batteries 4 are arranged, in consideration of this, the temperature difference α (for example, 3 ° C.) is used as a predetermined value, and the temperature difference is determined by the temperature difference value. It is determined whether or not each Ni-hydrogen battery 4 is substantially equal to the indoor temperature (outside air temperature) based on whether it is within α (AB ≧ α).

In conventional charging of a nickel-based battery, charging is started irrespective of the outside air temperature A and the battery surface temperature B. Therefore, the electric vehicle 5 that has finished traveling in a cold region is immediately heated. If the garage is charged, an erroneous full charge determination is made, but this is not the case with the present invention.

That is, the controller 9 calculates the temperature difference value α
If there is a temperature difference exceeding, the process proceeds to step S5, and a charging prohibition signal for prohibiting charging is output to the charger 12 through the charging port 11 and the signal line 15. As a result, charging of the Ni-hydrogen battery 4 by the charger 12 is not performed until the temperature difference between the outside air temperature A and the battery surface temperature B falls within the temperature difference value α.

Due to the prohibition of charging, the start of charging is waited until the battery surface temperature B becomes substantially equal to the outside air temperature A.

Next, the routine proceeds to step S10, where the suction fan 20 is operated. By the operation of the suction fan 20, the battery surface temperature B increases faster than the battery surface temperature B naturally increases.

To explain this point, warm air (outside air) in the garage 1 is taken into the battery tray 6 through the outside air intake 19 and the intake 16 by the suction of the suction fan 20. The air is blown to each Ni-hydrogen battery 4 in the tray 6.

Here, since the Ni-hydrogen battery 4 of the electric vehicle 5 traveling outdoors under minus is cold, the Ni-hydrogen battery 4 is warmed by the warm outside air in the garage 1.

As a result, the battery surface temperature B of the Ni-hydrogen battery 4 quickly rises to a temperature substantially equal to the indoor temperature (outside air temperature), and the temperature difference from the outside air temperature A is eliminated.

When it is determined in step S4 that the average battery surface temperature B of each Ni-hydrogen battery 4 has become substantially equal to the indoor temperature, the controller 9 sets the outside air temperature to a subsequent rise in the end-of-charge temperature. It is determined that there is no need to affect the detection, and the process proceeds to step S6, where
And outputs a charge start signal to start charging.

As a result, the charger 12 is connected to the charging port 11
Is supplied with power required for charging.

In step S9, the operation of the suction fan 20 is performed, and each of the Ni-hydrogen batteries 4 is charged with cooling in the indoor air (outside air), that is, charged while suppressing a temperature rise due to an exothermic reaction caused by the charging. . This allows
Charging is continued while ensuring an environment for accurately reading the temperature rise at the end of charging.

During this charging, the controller 9 detects a change in the battery surface temperature B of the Ni-hydrogen battery 4, and as shown in step S7, increases the temperature at the end of charging (for example, 0.3 ° C. per minute). (A small temperature change at the moment of about 0.5 ° C.).

In step S7, if there is a temperature rise (shown in FIG. 3) observed at the end of charging, the controller 9 determines that only water electrolysis has been performed and determines that the battery is fully charged. A charge end signal for stopping charging is output, and the suction fan 20 is stopped.

Thus, charging of the Ni-hydrogen battery 4 is completed. After the start of charging, if the temperature in the garage 1 suddenly changes for some reason and a difference occurs between the battery temperature and the outside air temperature, a charging prohibition signal for prohibiting charging is output to the charger 12. The charger 12 is stopped. However, when the outside air temperature A becomes equal to the battery surface temperature B again, charging is started.

Thus, even when the battery has a considerable temperature difference indoors and outdoors, the temperature rise of the battery due to the outside air is suppressed, and the full charge determination of the Ni-hydrogen battery 4 is accurately performed by using the temperature rise at the end of charging. Can be.

As a result, the Ni-hydrogen battery can be fully charged correctly.

Further, if the temperature difference does not prevent the temperature rise at the end of charging, the charging is immediately started while cooling the battery as before, so that it can be used in any environment.

In addition, when the temperature difference between the outside air temperature A and the electric surface temperature B exceeds a predetermined value, the indoor air (outside air) is blown to the Ni-hydrogen battery 4 so that even when there is a considerable temperature difference indoors and outdoors. The charging can be started as soon as possible.

In one embodiment, an example using a Ni-hydrogen battery has been described. However, the present invention is not limited to this, and a battery that determines full charge by using the other end-of-charge temperature rise, that is, nickel The present invention can be applied to a case where a nickel-based battery using a member is used.

In one embodiment, charging in a cold region has been described as an example. However, the charging is not limited to this. Needless to say, the present invention can also be applied to a case where a hydrogen battery is charged).

[0061]

As described above, according to the first aspect of the present invention, it is possible to accurately determine whether or not a nickel-based battery is fully charged even when there is a considerable temperature difference indoors and outdoors.

Furthermore, if the temperature difference does not prevent the temperature rise at the end of charging, the charging is immediately started while cooling the battery, as in the past, so that it can be used in any environment.

According to the invention described in claim 2, according to claim 1
In addition to the above-mentioned effects, even when charging with a considerable temperature difference indoors and outdoors, the difference between the outside air temperature and the battery surface temperature of the nickel-based battery is quickly eliminated by the ventilation of the outside air. It has the effect that it can be done.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a charging device for a nickel-based battery for an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating control performed by the charging device when charging a Ni-hydrogen battery indoors and outdoors when there is a considerable temperature difference.

FIG. 3 is a diagram for explaining characteristics of temperature rise at the end of charging of a Ni-hydrogen battery used for detecting full charge of the battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Garage 4 ... Ni-hydrogen battery (nickel-based battery) 5 ... Electric vehicle 8 ... Electric motor 9 ... Controller (control means) 11 ... Charging port 12 ... Charger 14 ... Charging connector 20 ... Suction fan (blowing means) 22 ... temperature sensor (battery temperature detecting means) 23 ... outside air temperature sensor (outside air temperature detecting means).

Claims (2)

[Claims] A battery charger for charging a nickel-based battery for an electric vehicle; a battery temperature detecting unit for detecting a temperature of the nickel-based battery; an outside air temperature detecting unit for detecting a temperature of outside air; Before charging, when the temperature difference between the temperature of the battery and the temperature of the outside air is within a predetermined value based on the temperature information from the battery temperature detection means and the outside air temperature detection means,
A charging device for a nickel-based battery for an electric vehicle, comprising: control means for starting charging of the nickel-based battery and charging the battery until a temperature rise at the end of charging is detected at the time of charging. 2. The air blower according to claim 1, wherein said controller is configured to blow air to said nickel-based battery when a temperature difference between a temperature of said battery and a temperature of outside air exceeds said predetermined value before charging said nickel-based battery. The charging device for a nickel-based battery for an electric vehicle according to claim 1, further comprising a unit.