JP3390502B2 - Rechargeable battery charging method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging method for two secondary batteries, and more particularly to a charging method for a secondary battery which enables efficient and rapid charging.

[0002]

2. Description of the Related Art Secondary batteries represented by nickel-hydrogen secondary batteries or nickel-cadmium secondary batteries are widely used as operating power sources for various equipment systems such as mobile phones and portable image pickup devices. Has been converted.
In other words, this type of secondary battery is capable of ensuring or storing electric power by a so-called charging operation, and repeatedly driving (discharging) a load using the ensured or stored electric power as a power source. As such, it has been put into practical use by being incorporated in various equipment systems.

By the way, in any case of the secondary battery, charging and discharging are the main functions as described above, and from the viewpoint of safety, the end voltage of charge and the end voltage of discharge are set as the respective limits. Charging and discharging are performed with a voltage within the limit range. The charging efficiency of the secondary battery depends on the temperature (charging temperature) of the secondary battery to be charged, and when the temperature is high (for example, about 45 ° C. or higher), the charging efficiency decreases with an increase in oxygen generation. As a result, the battery life (discharging action) is shortened. On the other hand, when the temperature of the secondary battery is as low as about 5 ° C, oxygen generation during charging is reduced, so that the charging efficiency itself is improved. However, if the charging temperature is 5 ° C, for example
In the low temperature range below, the oxygen absorption reaction at the negative electrode decreases, so when a large current is passed for quick charging, the internal pressure of the battery rises, resulting in battery life (damage to the battery, etc.)
Bring about a decline. Therefore, for example, when performing rapid charging, avoid charging below 5 ° C, perform charging within the temperature range of 5 to 45 ° C, and ensure that the battery temperature during charging is 45 ° C.
A method of stopping charging when the temperature exceeds about ℃ is generally adopted.

[0004]

As described above, in the rapid charging of the secondary battery, the temperature range in which charging is generally possible (appropriate charging temperature) is set in advance, and the full charge is actually reached. Even if the battery temperature exceeds a certain temperature, the charging is stopped (terminated) to prevent or avoid damage or damage to the secondary battery due to overcharging. If the secondary battery charge temperature is 5 ° C or lower (low temperature), wait until the secondary battery temperature rises to about 5 ° C, which is the temperature at which charging can be started, and then start the required rapid charge. Will be done. That is, in the case of the rapid charging conventionally used, there is a problem in that the secondary battery is required to be used without being sufficiently charged, and the operation efficiency of the secondary battery is also reduced. In addition, such a problem further decreases the total operating efficiency and the charging operation efficiency of each secondary battery when a plurality of secondary batteries are arranged and combined in parallel. It can be said to accelerate.

The present invention has been made in consideration of the above circumstances. It is possible to solve or avoid a shortage of charge due to a high temperature due to charging of a secondary battery (while ensuring a full charge), while starting charging. By avoiding stagnation and shortening the charging time,
It is an object of the present invention to provide a secondary battery charging method capable of efficiently achieving required charging.

[0006]

A first method of charging a secondary battery according to the present invention is a method for performing constant current charging via an arithmetic control circuit based on a result of detecting a charging temperature of the secondary battery. In a method of charging a secondary battery, in a low temperature region until the temperature of the secondary battery reaches a temperature at which charging can be started, the secondary battery is preheated by a current supplied from a constant current charging circuit and then required for the secondary battery. When charging is advanced and the temperature exceeds the appropriate high temperature side for charging and reaches a predetermined high temperature, charging is temporarily stopped, and when the temperature of the secondary battery reaches below the appropriate high temperature side for charging due to natural cooling, a constant current is reached. A second rechargeable battery charging method according to the present invention is characterized by comprising an operation for recharging, and a second rechargeable battery charging method according to the present invention is applied to a plurality of rechargeable batteries connected in parallel. Operation control circuit based on the detection result of charging temperature A constant current charging circuit and an output switching circuit are controlled via a charging method for a secondary battery, in which the plurality of secondary batteries are charged as required, in a low temperature until the charging temperature of the secondary battery reaches a predetermined temperature. In the temperature range, after preheating with the current supplied from the constant current charging circuit, the required charging is advanced to the first secondary battery, and once the temperature exceeds the proper high temperature side charging temperature and reaches a predetermined high temperature, Until the temperature of the first secondary battery reaches the proper high temperature side or below for charging due to natural cooling after suspending charging, the output of the constant current charging circuit is output to the second secondary battery side by the output switching circuit. It is characterized by switching and charging and stopping similarly.

In the present invention, the predetermined temperature is a temperature at which charging can be started, and the low temperature region is a temperature range in which charging is not possible (charging avoidance) is a temperature at which charging is possible (adequate charging) is a high temperature side. Indicates the required maximum chargeable temperature. Further, the supply current from the constant current charging circuit that forcibly preheats and raises the temperature of the corresponding secondary battery from a low temperature region to a predetermined temperature is a current that does not affect battery life (preliminary charging). Current) is desirable. Since these respective temperatures and the charging current for preheating differ depending on the type, structure or capacity of the secondary battery, it is necessary to pay attention to these points.

In the present invention, the determination of a predetermined high temperature exceeding the proper high temperature side for charging, in other words, the time at which the required charging is stopped, is the temperature rise per unit time of the secondary battery during this charging. May be a sudden increase. In other words, in the process of charging the secondary battery, the temperature rise per unit time of the secondary battery changes rapidly as it approaches or reaches the fully charged state (temperature differential control), and the required charging is performed. It is also possible to determine that it is time to stop.

Further, in the present invention, as a power source for charging, a commercial AC power source converted into a direct current having an appropriate voltage is used. In addition, a power source such as a fuel cell is used. Alternatively, electric power generated from a gasoline engine or a diesel engine may be used.

[0010]

In the present invention, the charging temperature of the secondary battery is detected during the rapid charging process of the secondary battery, and the constant current charging circuit of the constant current charging circuit is detected through the arithmetic control circuit in the fully charged state or in the state close to the fully charged state. By suspending output (charging) and naturally cooling to the proper temperature side for charging, by performing rapid charging again,
Further, by repeating this operation as appropriate, charging in a state closer to full charging can be achieved.

Further, in a form in which a plurality of secondary batteries are arranged in parallel, the charging temperature of each secondary battery is detected, and the constant current charging circuit and the output switching circuit are controlled via the arithmetic control circuit, In performing the required charging, the first secondary battery is preheated and set to a temperature at which charging can be started, and then the required charging is performed on the first secondary battery. Then, when the charging temperature of the first secondary battery reaches a high temperature exceeding the appropriate high temperature side for charging, the charging is temporarily stopped,
The output switching circuit switches the output of the constant current charging circuit to the side of the second secondary battery to perform preheating, charging and rest as in the case of the first secondary battery. That is, the state of charge of the first secondary battery is temporarily grasped by the temperature rise change of the first secondary battery, the charging is temporarily stopped based on the state of charge (the degree of charging), and the charging is performed again. The natural cooling time until the temperature reaches a temperature that can be performed is switched to the charging of the second secondary battery and the required charging of the second secondary battery is performed, so that the charging operation is continuous and efficient. It will progress well.

The enabling of the charging operation that makes it easy to achieve the fully charged state, combined with the forcible securing of the temperature at which charging can be started by preheating, makes the charging more efficient and shortens the charging operation. This will greatly contribute to the achievement of the realization of a longer life of the secondary battery.

[0013]

Embodiments of the present invention will be described below with reference to FIGS.

First, FIG. 1 is a block diagram schematically showing an embodiment of a method for charging a secondary battery according to the present invention. 1 is an input power source, 2 is a constant current control circuit, and 3 is the constant current control circuit. 2 is an output switching circuit for switching the output of 2; 4a is a first secondary battery (for example, nickel-hydrogen secondary battery) to be charged to which a constant current charging current output is applied via the output switching circuit 3; Similarly, a second secondary battery to be charged (for example, a nickel-hydrogen secondary battery) to which a constant current charging current output is applied via the output switching circuit 3, 5a and 5b are the first secondary battery to be charged. A temperature detection sensor, which is arranged in the vicinity of each of the secondary battery 4a and the second secondary battery 4b, and detects the temperature of the secondary batteries 4a, 4b, and 6 is the temperature detection sensor based on the temperature information from the temperature detection sensors 5a, 5b. Controls the current control circuit 2 and the output switching circuit 3, respectively. It is a calculation control circuit. here,
The arithmetic control circuit 6 controls the output of the constant current control circuit 2 according to the battery temperature signals from the temperature detection sensors 5a and 5b, and includes a rapid charge command 7a, a preliminary charge (preliminary heating) command 7b,
The output switching command 7c is output respectively.

Next, the charging operation in the illustrated embodiment will be described. Fig. 2 (a) shows the relationship between the charging time and the battery voltage of the secondary batteries 4a, 4b to be charged, and Fig. 2 (b) shows the charging time and the temperature change of the secondary batteries 4a, 4b to be charged. FIG. In FIG. 2B, t ₁ is the upper limit of the temperature at which charging is not possible, t ₂ is the temperature at which charging can be started, t ₃ is the temperature above the temperature at which charging is possible (the temperature at which charging is suspended), and t ₄ is the temperature at which charging is restarted. In the temperature range of t _{1 to} t _2, the temperature is such that preheating is required before charging, and in this temperature range, the charging current can be supplied at a level that does not affect the battery life. In addition, charging (rapid charging) can be started or charged within the temperature range of t ₂ to t ₄ . Furthermore, Fig. 2 (a)
In (b) and (b), the area A on the horizontal axis shows the time of precharging,
Area is for fast charging to secondary battery 4a, area C is for secondary battery
Stop charging to 4a ・ When the secondary battery 4b is being rapidly charged, in the D area is stopping charging to the secondary battery 4b ・ When restarting the rapid charging to the secondary battery 4a, in area E is the secondary battery 4a Charging is suspended and rechargeable battery 4b is rapidly charged again.

First, the temperature t of the first secondary battery 4a to be charged is detected by the temperature detection sensor 5a, and the detection signal is sent to the arithmetic control circuit 6. Here, the arithmetic control circuit 6 is
When the temperature of the first secondary battery 4a is t ₁ <t <t ₂ , the output of the constant current control circuit 2 is changed to the first by the output switching command 7c.
While switching to the secondary battery 4a side, the precharge (preheat) command 7b is output to the constant current control circuit 2, and the first secondary battery 4a
Preheat while precharging. This pre-charge
By the preheating, the temperature t of the first secondary battery 4a becomes t ₂ ≦
At the time when the temperature detection sensor 5a detects that t has been reached (when the temperature reaches the temperature at which rapid charge can be started), the arithmetic control circuit 6 outputs a rapid charge command 7a to the constant current control circuit 2 to request Perform quick charge of. In this process,
As shown in FIG. 2 (b), the battery voltage t changes as shown in FIG. 2 (a), and the battery temperature t rises to a temperature (charging stop or rest temperature) t ₃ that exceeds the appropriate charging temperature, and t = t ₃
At the point of time, the output of the constant current control circuit 2 is switched to the side of the second secondary battery 4b by the output switching command 7c from the arithmetic control circuit 6, while the required rapid charging for the first secondary battery 4a is stopped. . At this point, generally, the temperature t of the second secondary battery 4b has also risen to about t = t _2, so that the preliminary charging (preheating) can be omitted.

Then, by stopping (pausing) the required rapid charging of the first secondary battery 4a, the first secondary battery 4a is stopped.
Is naturally cooled, and the battery temperature t is the temperature t at which rapid charging can be resumed.
_When it decreases to _4, the output of the constant current control circuit 2 is changed to the first secondary battery by the output switching command 7c from the arithmetic control circuit 6 again.
While switching to the 4a side, the rapid charging for the second secondary battery 4b is stopped. The rapid charging and the rapid charging of the secondary batteries 4a and 4b are alternately repeated to achieve the fully charged state. More specifically, in the charging operation, the temperature (temperature per unit time) of each of the secondary batteries 4a and 4b rapidly rises as they approach full charge. Then, using the temperature differential signal as a guide, the fully charged state can be easily and accurately detected and the required charging can be performed.

In the above description, the case where the required rapid charging for the first secondary battery 4a is stopped (paused) is illustrated once, but it is not limited to one time and can be repeated. Along with the use of the temperature differential method, a higher fully charged state can be achieved. There are also 2 secondary batteries to be charged.
The number is not limited to one, and three or more may be arranged in parallel. Further, the secondary battery is not limited to the nickel-hydrogen secondary battery, but can be applied to rapid charging of other secondary batteries such as nickel-cadmium secondary battery, and similar effects can be obtained.

In the above description, the case of rapid charging of a plurality of secondary batteries has been exemplified. For example, in the charging circuit of FIG. 1, the output switching circuit 3 is omitted and one secondary battery to be charged is used. However, it is possible to charge the battery in a fully charged state in the same manner. That is, the temperature t of the secondary battery to be charged (for example, nickel-hydrogen secondary battery 4a) is detected by the temperature detection sensor 5a, and the detection signal is sent to the arithmetic control circuit 6. Here, when the temperature of the secondary battery 4a is t ₁ <t <t ₂ , the arithmetic control circuit 6 outputs a pre-charging (pre-heating) command 7b to the constant current control circuit 2, and the secondary battery 4 a Preheat while precharging 4a. When the temperature detection sensor 5a detects that the temperature t of the secondary battery 4a has reached t ₂ ≦ t due to this preliminary charging / preheating, the calculation control is performed. The circuit 6 outputs the quick charge command 7a to the constant current control circuit 2 to perform the required quick charge. In this process, the charging voltage changes as shown in FIG. 2 (a), and the battery temperature (charging temperature) t
Is also shown in FIG. 2 (b), increased to a temperature (charging stop or pause temperature) t ₃ greater than the chargeable temperature, t =
At the time of t _3, pauses required rapid charging of the secondary battery 4a.

[0020] Then, the required rapid charging of resting for said secondary battery 4a, the secondary battery 4a is naturally cooled, when the battery temperature t decreases to rapid charging resumable temperature t _4,
The secondary battery 4a is again sent by the quick charge command 7a from the arithmetic control circuit 6.
Then, the constant current control circuit 2 outputs to the side, and the secondary battery 4a is rapidly charged. The rapid charging and the suspension of the rapid charging for the secondary battery 4a are alternately repeated to achieve the charging in the fully charged state. More specifically, in the charging operation, the temperature (temperature per unit time) of the secondary battery 4a rapidly rises when approaching full charge, so the temperature rise per unit time, in other words, the temperature differential signal. As a guideline, the fully charged state can be detected easily and accurately,
The required charging can be performed.

[0021]

As can be seen from the above description of the embodiments, according to the present invention, when the battery temperature is low, the secondary battery to be charged can be precharged to a temperature at which it can be charged, and the secondary battery can be quickly charged. On the other hand, when the battery temperature exceeds the temperature at which proper charging is possible due to the rapid charging, the rapid charging is temporarily stopped, and if necessary, the second charged object is charged during the suspension time. Since the required rapid charging is performed on the secondary battery for the vehicle, the charging time can be shortened accordingly. Then, it is possible to efficiently achieve the required charging by detecting the full charge by repeating the rapid charging and the suspension of the rapid charging and the temperature differential control of the secondary battery corresponding to the charging state. .

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing an embodiment example of a charging method for a secondary battery according to the present invention.

FIG. 2 is a schematic view showing a state change of each secondary battery in an embodiment of a method for charging a secondary battery according to the present invention, in which (a) is a relationship between charging voltage and charging / switching / charging pause. Curve diagram,
(b) is a relationship curve diagram between the battery temperature and each operation of charging, switching, and charging suspension.

[Explanation of symbols]

1 ... Input power supply 2 ... Constant current control circuit 3 ... Output switching circuit 4a, 4b ... Secondary battery 5a, 5b ... Temperature detection sensor 6 ... Arithmetic control circuit 7a ... Quick charge command 7b
… Pre-charge (pre-heat) command 7c… Output switching command

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-190062 (JP, A) JP-A-5-129038 (JP, A) Actual development Sho-58-115077 (JP, U) JP-B-45- 4253 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 10/42-10/48 H02J ⁷ /00-7/12

Claims (2)

(57) [Claims] 1. A method of charging a secondary battery, which charges a constant current through an arithmetic control circuit based on a result of detecting a charging temperature of the secondary battery, wherein the temperature of the secondary battery is a temperature at which charging can be started. In the low temperature range until reaching, after the preheating by the current supplied from the constant current charging circuit, the required charging is advanced to the secondary battery, and when the charging reaches the predetermined high temperature beyond the proper high temperature side temperature. The charging of the secondary battery is stopped once, and when the temperature of the secondary battery reaches a temperature equal to or lower than an appropriate high temperature side for charging due to natural cooling, a constant current charging is performed again. How to charge. 2. Based on the result of detecting the charging temperature of each secondary battery for a plurality of secondary batteries connected in parallel,
In a secondary battery charging method for controlling a constant current charging circuit and an output switching circuit via an arithmetic control circuit to charge the plurality of secondary batteries as required, a temperature of the secondary battery reaches a predetermined temperature. In the low temperature range up to, the battery was preheated by the current supplied from the constant current charging circuit, and then the required charging was advanced to the first secondary battery, and the temperature reached a predetermined high temperature, exceeding the appropriate high temperature side temperature for charging. At this point, the charging is paused, and the output of the constant current charging circuit is controlled by the output switching circuit until the temperature of the first secondary battery reaches below the appropriate charging high temperature side due to natural cooling. A method of charging a secondary battery, which comprises switching to the battery side and similarly performing charging and charging suspension.