JPH08182215A - Charging method and charging apparatus for secondary battery - Google Patents

Abstract

PURPOSE: To provide adequate charging without generation of overcharging or insufficient charging, regardless of the history of the secondary battery to be charged. CONSTITUTION: A voltage difference Vd between the voltage during the feeding period of pulse current and the voltage during the no-feeding period is obtained from an arithmetic means 402. A battery condition judging means 404 judges the condition of battery depending on the fact that the voltage difference Vd is larger than the allowable maximum voltage difference or not and the first and second control command generating means 406 and 407 change, depending on the battery condition and voltage difference Vd, a current value of charging current and duty ratio to increase a discharge capacity without greatly increasing the battery temperature. Moreover, the first and second control command generating means 406 and 407 compensates, when the temperature judging means 405 judges necessity of temperature compensation, for a current value and duty ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging method and a charging device for a secondary battery using a pulse current.

[0002]

2. Description of the Related Art In recent years, with the development of portable equipment, use of secondary batteries as power sources for electronic equipment such as cassette tape recorders, VTRs, computers, communication equipment such as mobile phones, power equipment such as electric tools, etc. It has increased significantly. In particular, in portable equipment, there is an increasing demand for lightweight, compact, and high-capacity rechargeable batteries that can be rapidly charged. Further, in the portable device, at the same time, it is desired that the rapid charging device be downsized.

In charging these secondary batteries, a constant current charging method is generally used in which charging is performed at a constant current or constant voltage of about 0.1 to 1.0C. Since this charging method requires a long time for charging, in recent years, rapid charging with a constant current of 1.0 C or more has become the mainstream, and in addition, JP-A-64-8
There is also a charging method such as the invention described in No. 1628 in which charging is performed by a constant current having a pulse waveform to reduce gas generation due to charging and improve charging efficiency.

There is a -ΔV detection method as one of the charging control methods for nickel-cadmium batteries. This is to detect a peak voltage at which the rate of change in battery voltage over time, that is, the rate of voltage change, changes from positive (increases with time) to negative (decreases with time), and detects that the battery voltage has decreased by ΔV from the peak voltage. It is a method to stop charging. However, even in the case of the same battery, the electrode of the secondary battery is inactivated depending on its storage state. When the secondary battery that has been deactivated is charged, the charging characteristics are different from normal ones.
For example, when charging, the peak does not appear in the range where it should appear, and the voltage gradually rises. Alternatively, the first peak may appear immediately after the start of charging (within a few minutes), and then the second peak may appear again at the point where the charging is completed.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
No. 628 does not consider the history and temperature of the secondary battery in charging with a constant current having a pulse waveform, and the secondary battery at the end of its life is charged in the same manner as a new battery.・ In the case of hydrogen batteries, there is a danger that the amount of heat generated during charging will be extremely large.

Depending on the history of the battery, for example, when a battery for long-term storage is charged with a -ΔV detection type charging device, which is widely used as a charging system for nickel-cadmium batteries, -ΔV may be detected. However, there are drawbacks in that the battery cannot be overcharged due to failure of charging, or that it is impossible to carry out necessary charging by detecting -ΔV at the start of charging and assuming that charging is completed.

An object of the present invention is to increase discharge capacity without causing overcharging or insufficient charging, regardless of the history of the secondary battery to be charged, and without significantly increasing the temperature of the secondary battery. It is to provide a charging method and a charging device for a secondary battery that can achieve the above.

Another object of the present invention is to provide a charging method and a charging device for a secondary battery which does not malfunction even if the -ΔV detection method is used as a charging control method.

Still another object of the present invention is to provide a charging method and a charging device for a secondary battery which can improve charging efficiency in response to changes in ambient temperature.

[0010]

The charging method of the present invention is intended for a secondary battery charging method for charging a secondary battery with a pulse current having a predetermined duty ratio Q.

In the present invention, the voltage Von during the energization period of the pulse current and the voltage Voff during the non-energization period of the pulse current.
Is measured to obtain the difference voltage Vd between the two voltages. Then, charging is performed by changing at least one of the duty ratio Q and the current value I of the pulse current according to the difference voltage Vd so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery.

When charging is performed by changing at least one of the duty ratio Q and the current value I of the pulse current according to the difference voltage Vd, the secondary battery to be charged is a new and normal battery, and the secondary battery to be charged is a normal battery. It is preferable to change the charging condition depending on whether the battery has been left for a long period of time, or has been charged and discharged a large number of times to reach the end of its life. Therefore, in one example of a more specific method of the present invention, the following method is adopted. First, when the difference voltage Vd is smaller than the maximum allowable difference voltage Vur, it is determined that the secondary battery is in a normal state. In this case, the duty ratio Q and the current value of the pulse current are set in inverse proportion to the change in the difference voltage Vd so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. Charging is performed by changing I. Here, the "predetermined inverse proportional relationship" is determined in accordance with the type of the battery, and is not limited to the case where the inverse proportional relationship is obtained continuously with the change of the difference voltage Vd, but the difference It also includes a stepwise inverse proportional relationship in which the duty ratio Q and the current value I of the pulse current are changed in the inverse proportional direction when the change width of the voltage Vd exceeds a predetermined value. In the embodiments described later, a stepwise inverse proportional relationship is adopted.

The magnitude of the difference voltage Vd is proportional to the state of the secondary battery, especially the internal resistance. The small difference voltage Vd means that the internal resistance of the battery is small. Therefore, in this state, even if the charging current is increased, the battery temperature of the secondary battery does not rise much. On the other hand, a large difference voltage Vd means a large internal resistance of the battery. Therefore, if the charging current is increased in this state, the amount of heat generation increases, and the rate of increase in the battery temperature of the secondary battery increases. Therefore, in the embodiment of the present invention, when the secondary battery is in the normal state, the duty ratio Q and the current value I of the pulse current are decreased as the difference voltage Vd increases, and the duty ratio decreases as the difference voltage Vd decreases. Q and the current value I of the pulse current are increased. From another perspective, this is
The larger the difference voltage Vd, the smaller the amount of charge given to the battery by one pulse charge, and the smaller the difference voltage Vd, the larger the amount of charge given to the battery by one pulse charge.

When the difference voltage Vd is equal to or higher than the maximum allowable difference voltage Vur, it is determined that the secondary battery is in an abnormal state (left for a long time or the end of life). In this case, a pulse current having a larger current value than the current value used when the secondary battery is in the normal state is used with a duty ratio smaller than the minimum duty ratio of the duty ratio Q used when the secondary battery is in the normal state. To charge. As described above, the large difference voltage Vd means that the internal resistance of the secondary battery is large. There are various causes for increasing the internal resistance of the secondary battery, and one of them is inactivation or oxidation of the electrode surface. Therefore, in the present invention, a large current is applied with a short pulse width. Passing a large current with a short pulse width here means applying a high voltage, thereby charging the secondary battery while destroying the inactive layer or the oxide film on the electrode surface.

When charging the secondary battery, the battery temperature or ambient temperature of the secondary battery affects the charging characteristics. For example, when the battery temperature or the ambient temperature of the secondary battery is low, the internal pressure in the battery case of the secondary battery is high, the battery voltage is high, and the absorption performance of the gas generated during charging is high. It's getting worse. Further, when the battery temperature or the ambient temperature of the secondary battery is high, the gas absorption performance is improved, the internal pressure is low, and the battery voltage is low. Therefore, when charging the secondary battery, if the charging conditions are determined in consideration of these conditions, the secondary battery can be charged more efficiently and satisfactorily. Therefore, in the present invention, the battery temperature T or the ambient temperature of the secondary battery is measured, and the duty ratio Q and the current value I are temperature-corrected according to the battery temperature T or the ambient temperature.

As a concrete method of temperature correction, for example, when the battery temperature T or the ambient temperature is high, the duty ratio Q and the current value I are set so that the duty ratio Q and the current value I become larger than a predetermined relationship. Correct at least one of the values I. When the battery temperature or the ambient temperature is high, the gas absorption performance is high, so the secondary battery can be charged without any problem even if the charge amount is increased. Therefore, if such temperature correction is performed, the charging efficiency becomes high. If the duty ratio Q or the current value I is excessively increased by the temperature correction, the temperature rise width of the battery becomes large. Therefore, in consideration of this point, the increase amount of the duty ratio Q or the current value I must be appropriately determined. .

Further, when the battery temperature T or the ambient temperature is low, the duty ratio Q and the current value I are set so that the duty ratio Q and the current value I become smaller than a predetermined relationship.
Correct at least one of the. When the battery temperature or ambient temperature is low, the gas absorption performance is degraded as described above.Therefore, reduce the charge amount and lengthen the non-energization period of the pulse current to absorb the generated gas as much as possible. .

The determination as to whether or not the temperature should be corrected preferably has a certain temperature range. By setting such a temperature width, that is, a set temperature range (T1 <T <T2), unnecessary temperature correction can be prevented.

The charging device to which the present invention is to be improved is a DC power supply device 1 capable of changing a current value in accordance with a control command, and a switch arranged between the DC power supply device 1 and the secondary battery 5. Circuit 2 and switch circuit 2 according to a control command
A control signal generating circuit 3 for outputting a control signal for turning on / off the switch, and a control device 4 for outputting a control command to the control signal generating circuit 3 and the DC power supply device 1 are provided to turn on / off the switch circuit. A charging device for charging a secondary battery with a pulse current having a predetermined duty ratio Q, which specifically executes the charging method of the present invention.

The control device 4 used in the charging device of the present invention is
A voltage measuring unit 401 that measures the voltage of the secondary battery, and a calculation unit 402 that measures the voltage Von during the energization period of the pulse current and the voltage Voff during the non-energization period of the pulse current to obtain the difference voltage Vd between the two voltages. And a control command for changing the duty ratio Q and the current value I of the pulse current according to the difference voltage Vd so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. And a charge completion confirmation unit 408 that stops the operation of the control device when the completion of charging is confirmed.

The structure of the charging completion confirmation means 408 is arbitrary. When the −ΔV detection method is adopted, charging may be performed in consideration that the first peak may appear immediately after the start of charging (within a few minutes), and then the second peak may appear again at the time of completion of charging. Even if the peak is detected for a predetermined time after the start, it is preferable to configure the charging completion confirming means so as to ignore the detection of the peak. Further, the charging completion confirmation operation may not be performed for a predetermined time after the start of charging. By doing this, the secondary battery can be reliably charged.

The control command generator 403 may be configured to temperature-correct the duty ratio Q and the current value I according to the output of the temperature measuring unit 6.

The control command generating section 403 can be composed of a battery state determining means 404, a temperature determining means 405, a first control command generating means 406, and a second control command generating means 407. The battery state determination means 404 is
When the difference voltage Vd is smaller than the maximum allowable difference voltage Vur, it is determined that the secondary battery is in a normal state, and when the difference voltage Vd is the maximum allowable difference voltage Vur, it is determined that the secondary battery is in an abnormal state. . The temperature determination means 405 determines that the battery temperature T of the secondary battery or the ambient temperature is within a set temperature range (T1 <T <T2)
Or not. First control command generating means 40
6, the battery state determination means determines that the secondary battery is in a normal state, and the temperature determination means 405 confirms that the battery temperature T or the ambient temperature is within the set temperature range (T1 <T <T2). When the determination is made, charging is performed by changing the duty ratio Q and the current value I of the pulse current according to a predetermined inverse proportional relationship with respect to the change of the difference voltage Vd, and the temperature determination means 405 causes the battery temperature to change. When it is determined that T or the ambient temperature is higher than the set temperature range (T1 <T <T2), the temperature is corrected so that the duty ratio Q is increased according to the battery temperature T or the ambient temperature, and charging is performed. Then, the temperature determination means 405 determines that the battery temperature T is within the set temperature range (T
When it is determined that it is lower than 1 <T <T2), the control signal generation circuit 3 and the control signal generation circuit 3 are configured to perform temperature correction so as to reduce the duty ratio Q in accordance with the battery temperature T or the ambient temperature. A control command is output to the DC power supply device 1. The second control command generation means 407 is higher than the minimum duty ratio of the duty ratio Q determined by the first control command generation means 406 while the battery state determination means 404 determines that the secondary battery is in an abnormal state. A control command is output to the control signal generation circuit 3 and the DC power supply device 1 so that charging is performed using a pulse current having a small duty ratio and a current value larger than the current value determined by the first control command generation means 406.

[0024]

The difference voltage Vd between the voltage Von during the energization period of the pulse current and the voltage Voff during the non-energization period of the pulse current indicates the state of the secondary battery, that is, the state of the internal resistance. Therefore, the difference voltage Vd is monitored, and the duty ratio Q of the pulse current and the current value I of the pulse current are monitored according to the difference voltage Vd.
By changing at least one of the above, regardless of the history of the secondary battery to be charged, the occurrence of overcharging or insufficient charging can be prevented,
Moreover, the discharge capacity can be increased without significantly increasing the temperature of the secondary battery.

[0025]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing an embodiment of a charging device for carrying out the method of the present invention. In the figure, 1 is a DC power supply device capable of changing a current value according to a control command, 2 is a switch circuit, and 3 is a control signal generator for outputting a control signal for turning on / off the switch circuit 2 according to the control command. Circuit. Four
Is a control device that outputs a control command to the control signal generation circuit 3 and the DC power supply device 5, reference numeral 5 is a secondary battery to be charged, and reference numeral 6 is a temperature measuring unit that measures the temperature or ambient temperature of the secondary battery 5.

The control device 4 has a built-in CPU (Central Processing Unit) 41, a memory 42, an output port 43, an A / D converter 44 for an input port, and the like. Is input to the A / D converter 44. This input is processed by the CPU 41 using software stored in the CPU 41 and the memory 42, and a control command signal is output from the output port 43. The memory 42 also stores predetermined data as shown in FIGS. 9 to 11 regarding the secondary battery to be charged. The temperature measuring unit 6 is composed of a temperature detecting element such as a thermistor whose resistance value changes with temperature. The control signal generation circuit 3 receives the control command signal from the control device 4 and controls ON / OFF of the switch circuit 2. A transistor is suitable as a switching element of the switch circuit 2, and when the switch circuit 2 is ON, a constant current is passed through the secondary battery 5.

FIG. 2 shows a concrete example of the configuration realized by using software in the control device 4 in FIG. 1. Reference numeral 401 denotes a voltage measuring unit for measuring the voltage of the secondary battery. The measuring unit 401 outputs the battery voltage V converted from analog to digital by the A / D converter 44 as a signal for easy arithmetic processing. Reference numeral 402 denotes a voltage difference (Von-Vof) between the two voltages by measuring the voltage Von during the pulse current conduction period and the voltage Voff during the pulse current non-conduction period.
f) A calculating means for obtaining Vd. Reference numeral 403 is for charging by changing the duty ratio Q and the current value I of the pulse current according to the difference voltage Vd so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. Is a control command generation unit that outputs the control command. Four
Reference numeral 08 denotes a charging completion confirming unit that stops the operation of the control device 4 when confirming the completion of charging. The charging completion confirming means is configured not to perform the charging completion operation or to ignore the detection of the completion of charging until a predetermined period of time elapses after the start of charging.

The control command generator 403 temperature-corrects the duty ratio Q and the current value I according to the output of the temperature measuring unit 6. Reference numeral 404 denotes a battery state determination unit that determines that the secondary battery is in a normal state when the difference voltage Vd is smaller than the maximum allowable difference voltage Vur (0.1 V in this embodiment), and the difference voltage Vd is the maximum allowable value. It is determined that the secondary battery is in an abnormal state when the difference voltage is Vur or more. 405 indicates that the battery temperature of the secondary battery or the ambient temperature T is within a set temperature range (T1 <T <T2
) Is a temperature determination means for determining whether or not In this embodiment, the temperature correction is not performed when the battery temperature of the secondary battery or the ambient temperature T is within the set temperature range (T1 <T <T2), and when the temperature is out of the set temperature range, the temperature correction is performed. . For example, when charging a nickel-hydrogen battery, the lower limit temperature T1 can be about 5 ° C and the upper limit temperature T2 can be 35 ° C. Needless to say, it is also possible to set one reference temperature without setting such a set temperature range and always perform temperature correction when the reference temperature is deviated from this one reference temperature.

Reference numeral 406 is a first control command generating means, 407.
Is a second control command generating means. In the first control command generation means 406, the battery state determination means 404 determines that the secondary battery is in a normal state, and the temperature determination means 405 determines that the battery temperature or the ambient temperature T is within the set temperature range (T1 <T < T
2) If it is determined that the voltage is within the range, the difference voltage Vd
The charging is performed by changing the duty ratio Q and the current value I of the pulse current in a predetermined inverse proportional relationship as shown in FIGS. Also, the temperature determination means 40
5 is the battery temperature or the ambient temperature T is the set temperature range (T1 <
If it is determined that the value is higher than T <T2), FIG.
The duty ratio Q is higher than the value determined based on the data shown in
Is corrected according to the battery temperature or the ambient temperature T to perform charging (see FIG. 11). When the temperature determination means 405 determines that the battery temperature or the ambient temperature T is lower than the set temperature range (T1 <T <T2), the battery is lower than the value determined based on the data shown in FIG. A control command signal is output to the control signal generation circuit 3 and the DC power supply device 1 to perform temperature correction (see FIG. 11) so as to reduce the duty ratio Q according to the temperature T or the ambient temperature and perform charging.

In the present embodiment, the target of temperature correction is only the duty ratio Q, but the current value I may be the target of temperature correction, or both may be the target of temperature correction. Is.

The second control command generating means 407, while the battery state determining means 404 determines that the secondary battery is in an abnormal state, the minimum duty of the duty ratio Q determined by the first control command generating means 406. The control signal generating circuit 3 and the DC power supply device 1 so that charging is performed using a pulse current having a duty ratio smaller than the ratio and a current value larger than the current value determined by the first control signal generating means 406.
The control command is output to. By doing so, a pulse current having a small pulse width and a large current value is passed through the battery, the inactive layer or the oxide film on the surface of the electrode is destroyed, and the charge acceptability is improved. When the voltage difference Vd becomes smaller than the maximum allowable difference voltage Vur during such charging, the second control command generating means 407 stops outputting the control command, and the first control command generating means 406 causes the control command to occur. Will be output.

In this embodiment, the duty ratio Q of the pulse current for charging the secondary battery 5 is changed by turning on / off the switch circuit 2 by the control signal from the control signal generating circuit 3. Further, the change of the charging current is, for example, as shown in FIG. 3, the switching transistors 11 to 11 which are FETs (field effect transistors) provided in the DC power supply device 1 as shown by a control command signal from the control device 4. The current value is changed by controlling 14 to change the series resistance value. In the configuration of FIG. 3, four resistors having different resistance values (R, 2R, 4R, 8R) are connected in series to the output part of the DC power supply 1a, and a transistor 11 composed of an FET 11 is connected in parallel to these resistors. To 14 are respectively connected. The current value can be controlled by turning on or off the selected transistor.

FIG. 4 shows the CPU 41 of the control device 4 of this embodiment.
3 is a flowchart showing an example of a software algorithm for operating the. When the charging of the secondary battery 5 is started, the control device 4 reads and stores the voltage Voff during the non-energization period (OFF time) of the pulse current of the secondary battery 5 in step ST1. Then, the pulse current is turned on in step ST2, and the voltage Von during the energization period of the pulse current is read in step ST3. Next, the pulse current is turned off in step ST4, and the battery temperature is measured by the temperature measuring unit 6 in step ST5. In the next step ST6, the control device 4 compares the battery voltage Voff when the charging current is not applied and the battery voltage Von when the charging current is applied to obtain the differential voltage Vd. Based on this difference voltage Vd, the current value I of the charging current and the duty ratio Q are determined in step ST7 to perform charging. Then, in step ST8, it is determined whether or not the charging is completed. If YES, the charging is stopped, and if NO, the process returns to step ST1.

In this embodiment, the voltage measuring section 401 is realized by steps ST1 and ST3, and step S
The calculating means 402 is realized by T6, and step ST7
The control command generator 403 is thereby realized. Step ST
8, the charging completion confirmation unit 408 is realized.

FIG. 5 is a detailed flowchart of a part of steps ST6 and ST7 (I decision flow) of the flowchart of FIG. In FIG. 5, step S in FIG.
Subsequent to T5, the above-mentioned difference voltage Vd is sequentially compared with a predetermined reference value in steps ST61 to ST63, and steps ST71 to ST71 are performed according to the determined magnitude of the difference voltage Vd.
In ST74, the current value I of the pulse current is determined to be a different value. The reference value is the value shown in FIG. 9, and is the value of the difference voltage Vd when changing the current value I. Although not shown in FIG. 5, the duty ratio Q is also based on FIG.
It is determined by the same flow as the determination of the current value I.

Then, in step ST75, it is determined whether the battery temperature or the ambient temperature T is within the set temperature range,
If YES, the process proceeds to step 8, and if NO, the current value I and the duty ratio Q are temperature-corrected based on the temperature measurement value of step 5 in FIG. 4 and the process proceeds to step 8. In this embodiment, as shown in FIG. 11, the temperature is corrected by the duty ratio Q. Current value I
A method for determining the magnitude of the duty ratio Q and a specific example of the temperature correction will be described later.

FIG. 6 is a detailed flowchart of step ST8 of the flowchart of FIG. In FIG.
After the start of charging, the battery voltage Von is measured in step 81, and it is determined in step 82 whether the battery voltage Von has reached the peak voltage. When the peak voltage is reached, it is detected in the next step 83 whether the battery voltage Von is lower than the peak voltage by ΔV. If the detection result is NO, the process returns to step ST1 in the flowchart of FIG. If the detection result is YES, it is checked in the next step ST84 whether or not the charging has continued for a certain period of time, and if NO, the process returns to step ST1 and if YES, the charging is stopped. This step ST84 is provided for the purpose of preventing the charging from being stopped when the first peak appears in the initial stage of charging. Note that step ST84 may be inserted before step ST81.

FIG. 7 (A) shows the manner of change of the pulse current, and FIG. 7 (B) shows the change with time of the battery voltage during charging by the pulse current. Figure 7
In (A), the charging pulse current is turned on at a predetermined time interval.
/ OFF is repeated. The controller reads and stores the battery voltage Voff when the pulse is OFF at points d and d'and the battery voltage Von when the pulse is ON at points e and e '. FIG. 7 (B) shows the curves of the above voltages Von and Voff with time, which are associated with charging. The difference voltages Vd are obtained by comparing the read battery voltages Von and Voff, and the magnitudes of the charging current and the duty ratio Q are changed according to the magnitudes of the difference voltages Vd.

For example, as shown in FIG. 9, when the differential voltage Vd is 0.04 V / cell or more, the charging current is 50% of the normal setting of 100%. This is because the heat generated inside the battery increases as the charging current increases.
Not only does the temperature rise of the battery become a problem, but if charging is continued for a long time while charging is in progress, the electrodes inside the battery will partially become overcharged, accelerating the deterioration of battery performance, This is because it is not preferable in terms of safety.

Even if the differential voltage Vd is 0.04 V / cell or more, 150% of the voltage is 0.1 V / cell or more.
Flow the charging current of. This is because, for example, in the case of a lead storage battery, the oxide film of lead sulfate or lead oxide on the electrode surface, which is a resistor formed by discharging, is destroyed.

Further, in order to prevent the temperature rise of the battery due to charging according to the relationship shown in FIG. 10, the duty ratio Q is also changed according to the magnitude of the difference voltage Vd.

Further, by correcting the current value I of the charging current and the duty ratio Q with the battery temperature or the ambient temperature T, more appropriate charging can be performed.

FIG. 8 shows the waveform of the charging current of the pulse current. As shown in the figure, the charging current has a positive pulse waveform, and charging ON / OFF is repeated at predetermined time intervals. The relationship between the charging ON and the charging OFF is represented by a duty ratio Q = ton / (ton + toff), and 0 <Q <1.
For the purpose of shortening the charging time, it is preferable to set the value as close to 1 as possible. However,
When a nickel-cadmium battery or a nickel-hydrogen battery is charged, gas is generated and the battery temperature rises. These reduce charging efficiency. Especially at low temperatures, the internal pressure of the battery is higher than at high temperatures, so it is preferable to lengthen the charge OFF time to provide a gas absorption time. As shown in FIG. Ratio Q
It is preferable that the charge OFF time is shortened and the duty ratio Q is increased at high temperatures. However, if the duty ratio Q is increased, the charging O
Since the FF time becomes short, the temperature rise becomes large. Therefore, it is necessary to set the duty ratio Q according to the battery in consideration of charging efficiency.

Next, according to the charging method of the present invention, the capacity 110
An example of charging a 0 mAh nickel-hydrogen battery is shown. In this embodiment, the charging current I and the voltage difference V shown in FIG.
Charging was controlled using the relationship with d and the relationship between the duty ratio Q and the voltage difference Vd shown in FIG. 10. The charging current I is 2.0 CmA at a voltage difference of 0.04 V or less, 0.04 to
It was 1.8 CmA at 0.07 V, 0.5 CmA at 0.07 to 0.10, and 3.0 CmA at 0.10 or more.
The maximum duty ratio Q is set to 0.90, and the duty ratio Q is gradually reduced as shown in the figure as the difference between the battery voltage Voff when the charging current is off and the battery voltage Von when the charging current is on increases. .

Further, these values are corrected by the battery temperature (or ambient temperature) as described above. For example, the duty ratio Q changes as shown in FIG. Assuming that the difference Von-Voff between the voltage during charging suspension and the voltage during charging is V1,
Normally, it is charged with Q1. However, when the ambient temperature is low, the duty ratio slides down to Q2, and when the ambient temperature is high, slides up to Q2.
It becomes 3. Similarly, the current value I of the charging current is
You may perform the correction | amendment which increases / decreases according to low. The charging current at the start of charging was 1.0 CmA.

FIG. 12 shows charge curves of batteries A, B and C having different histories, and curves A, B and C in FIG. 12 correspond to batteries A, B and C, respectively.
Battery A is 0.1C, 150% charged, 0.2C discharged 3 times
Battery B is a battery set for a long period of time and battery C is a battery at the end of its life. In the case of battery A, it is a so-called normal battery, and
Voltage difference V at the point (the point where Vd was calculated after the start of charging)
d is 0.030 V and the charging current value I is 2.0 Cm
A, the duty ratio Q is 0.85. b point, c point,
The same is true at point d. On the other hand, the battery B has a
The voltage difference Vd at the point is 0.065 V, and the voltage difference Vd at the point b
Is 0.065V, the voltage difference Vd at point C is 0.045V,
Since the voltage difference Vd at the point d is 0.038 V, the charging current changes to 1.0 CmA and 2.0 CmA, and the duty ratio Q changes to 0.60, 0.75 and 0.85. . Further, in the battery C, the voltage difference Vd is 0.
The charging is performed at 080 V, a current value of 0.5 CmA, and a duty ratio Q of 0.5.

Table 1 shows a 1100 mAh nickel-metal hydride battery charged by the charging method according to the present invention and conventional pulse charging (duty ratio 0.85, current value 1.0).
A comparison with that by CmA) is shown.

[0048]

[Table 1] Battery A is a battery that has been charged after performing 0.1 C, 150% charge and 0.2 C discharge for 3 cycles, battery B is a battery that has been left for a long time, and battery C is a battery that has reached the end of its life. The battery that has been left for a long period of time and the battery at the end of its life are charged by the charging method according to the present invention, the temperature rise is small, and the discharge capacity is obtained.

In the above-described embodiment, both the duty ratio Q and the current value I of the pulse current are changed and charged according to the difference voltage Vd. However, when the present invention is implemented, at least one of them is charged. You can change it.

[0050]

As described above, according to the charging method of the present invention, the pulse current is used for charging the secondary battery, and the difference voltage between the voltage during the energization period of the pulse current and the voltage during the de-energization period. Depending on the above, charging is performed by changing at least one of the duty ratio and the current value of the pulse current, so regardless of the history of the secondary battery to be charged, overcharging or insufficient charging can be prevented and good Can be charged. Moreover, the discharge capacity can be increased without significantly increasing the temperature of the secondary battery.

Further, the charging efficiency can be improved by correcting at least one of the duty ratio and the current value of the charging pulse current according to the temperature of the secondary battery or the ambient temperature.

Furthermore, according to the charging device of the present invention, the method of the present invention can be carried out extremely well.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a charging device of the present invention.

FIG. 2 is a block diagram showing a configuration example of a control device in FIG.

3 is a circuit diagram showing a configuration example of a DC power supply device in FIG.

FIG. 4 is a flowchart showing a charge control algorithm according to the embodiment of this invention.

FIG. 5 shows a step ST- in the flowchart of FIG.
6 is a flowchart specifically showing the contents of ST-7.

6 is a flowchart specifically showing the contents of step 8 in the flowchart of FIG.

FIG. 7A is a characteristic curve diagram showing a battery voltage measurement timing in the present invention, and FIG. 7B is a characteristic curve diagram showing a measured voltage curve.

FIG. 8 is a waveform diagram showing a variation example of the waveform of the charging pulse current according to the present invention in accordance with the battery temperature.

FIG. 9 is a characteristic curve diagram showing the relationship between the voltage difference and the charging current in the example of the present invention.

FIG. 10 is a characteristic curve diagram showing the relationship between the voltage difference and the duty ratio in the example of the present invention.

FIG. 11 is a characteristic curve diagram showing a temperature correction characteristic of a duty ratio in the example of the present invention.

FIG. 12 is a characteristic curve diagram showing charge curves of batteries having different histories.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC power supply device 1a DC power supply 2 Switch circuit 3 Control signal generation circuit 4 Control device 401 Voltage measurement unit 402 Calculation means 403 Control command generation unit 404 Battery state determination unit 405 Temperature determination unit 406 First control command generation unit 407 Second Control command generation means 408 Charge completion confirmation means 41 CPU 42 Memory 43 Output port 44 A / D converter 5 Secondary battery 6 Temperature measurement unit

Claims (9)

[Claims] 1. A charging method for a secondary battery, wherein a secondary battery is charged with a pulse current having a predetermined duty ratio (Q), wherein a voltage (Von) during the energization period of the pulse current and a non-existence of the pulse current. The voltage (Voff) during the energization period is measured to obtain the voltage difference (Vd) between the two voltages, and the voltage difference (Vd) is set so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. A charging method for a secondary battery, comprising charging at least one of the duty ratio (Q) and the current value (I) of the pulse current according to Vd). 2. A battery temperature (T) or an ambient temperature of the secondary battery is measured, and at least the duty ratio (Q) and the current value (I) are measured according to the battery temperature (T) or the ambient temperature. The method for charging a secondary battery according to claim 1, wherein one of them is corrected. 3. A charging method for a secondary battery, which charges a secondary battery with a pulse current having a predetermined duty ratio (Q), wherein a voltage (Von) during the energization period of the pulse current and a non-existence of the pulse current The voltage (Voff) during the energization period is measured to obtain the difference voltage (Vd) between the two voltages. When the difference voltage (Vd) is smaller than the maximum allowable difference voltage (Vur), it is determined that the secondary battery is in a normal state. Then, the duty ratio (Q) is set in a predetermined inverse proportional relationship with respect to the change of the difference voltage (Vd) so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. And charging is performed by changing the current value (I) of the pulse current. When the difference voltage (Vd) is equal to or higher than the allowable maximum difference voltage (Vur), the secondary battery is determined to be in an abnormal state, and Used when the secondary battery is in a normal state Charging is performed by using a pulse current having a current value larger than the current value used when the secondary battery is in a normal state with a duty ratio smaller than the minimum duty ratio of the duty ratio (Q). How to charge the next battery. 4. A battery temperature (T) or an ambient temperature of the secondary battery is measured, and when the battery temperature (T) or the ambient temperature is higher than a set temperature range, the duty ratio (Q) and the At least one of the duty ratio (Q) and the current value (I) is corrected so that the current value (I) becomes larger than the predetermined relationship, and the battery temperature (T) or the ambient temperature is set within a set temperature range. If it is lower than the above, at least one of the duty ratio (Q) and the current value (I) is corrected so that the duty ratio (Q) and the current value (I) become smaller than the predetermined relationship. The method for charging a secondary battery according to claim 1, wherein 5. A charging method for a secondary battery, comprising charging a secondary battery with a pulse current having a predetermined duty ratio (Q), the battery temperature (T) or the ambient temperature of the secondary battery being measured, The voltage (Von) during the energization period of the pulse current and the voltage (Voff) during the non-energization period of the pulse current are measured to obtain the difference voltage (Vd) between the two voltages, and the difference voltage (Vd) is the maximum allowable value. When it is smaller than the voltage difference (Vur), it is determined that the secondary battery is in a normal state, and the battery temperature (T) or the ambient temperature is within the set temperature range (T1).
In the case of <T <T2), a predetermined inverse proportional to the change of the differential voltage (Vd) so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. Therefore, charging is performed by changing the duty ratio (Q) and the current value (I) of the pulse current, and the battery temperature (T) or the ambient temperature is set within a set temperature range (T1 <T
If it is higher than <T2), the battery temperature (T or ambient temperature is corrected according to the ambient temperature so that the duty ratio (Q) is increased and charging is performed to set the battery temperature (T) or ambient temperature. When the temperature is lower than the temperature range (T1 <T <T2), temperature is corrected so that the duty ratio (Q) is reduced according to the battery temperature (T) or the ambient temperature, charging is performed, and the difference voltage ( When Vd) is equal to or more than the allowable maximum difference voltage (Vur), it is determined that the secondary battery is in an abnormal state, and is smaller than the minimum duty ratio of the duty ratio (Q) used when the secondary battery is in the normal state. A charging method for a secondary battery, comprising: charging using a pulse current having a larger current value than the current value used when the secondary battery is in a normal state at a duty ratio. 6. A DC power supply device (1) capable of changing a current value according to a control command, and a switch circuit (2) arranged between the DC power supply device (1) and a secondary battery (5). )
And the switch circuit (2) is turned on according to the control command.
Control signal generation circuit for outputting control signal to turn off (3)
And a control device (4) that outputs the control command to the control signal generation circuit (3) and the DC power supply device (1), and turns on and off the switch circuit to set a predetermined duty ratio ( A charging device for a secondary battery that charges a secondary battery with the pulse current of Q), wherein the control device (4) measures a voltage of the secondary battery (401).
And a calculating means (402) for measuring a voltage (Von) during the energization period of the pulse current and a voltage (Voff) during the non-energization period of the pulse current to obtain a difference voltage (Vd) between the two voltages. The duty ratio (Q) and the current value (I) of the pulse current are changed according to the difference voltage (Vd) so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. A control command generator (403) for outputting the control command for performing charging by means of charging, and a charging completion confirmation means (408) for stopping the operation of the control device when the completion of charging is confirmed. Rechargeable battery charger. 7. A DC power supply device (1) capable of changing a current value according to a control command, and a switch circuit (2) arranged between the DC power supply device (1) and a secondary battery (5). )
And the switch circuit (2) is turned on according to the control command.
Control signal generation circuit for outputting control signal to turn off (3)
And a control device (4) that outputs the control command to the control signal generation circuit (3) and the DC power supply device (1), and turns on and off the switch circuit to set a predetermined duty ratio ( A charging device for a secondary battery that charges a secondary battery with the pulse current of Q), comprising a temperature measuring unit (6) for measuring a battery temperature (T) or an ambient temperature of the secondary battery, The device (4) includes a voltage measuring unit (401) for measuring the voltage of the secondary battery.
And a calculating means (402) for measuring a voltage (Von) during the energization period of the pulse current and a voltage (Voff) during the non-energization period of the pulse current to obtain a difference voltage (Vd) between the two voltages. The duty ratio (Q) and the current value (I) of the pulse current are changed according to the difference voltage (Vd) so as to increase the discharge capacity without significantly increasing the temperature of the secondary battery. The control command generation unit (403) that outputs the control command for performing charging by charging, and a charging completion confirmation unit (408) that stops the operation of the control device when the completion of charging is confirmed. The generator (403) temperature-corrects the duty ratio (Q) and the current value (I) according to the output of the temperature measuring unit 6, and is a secondary battery charging device. 8. A DC power supply device (1) capable of changing a current value according to a control command, and a switch circuit (2) arranged between the DC power supply device (1) and a secondary battery (5). )
And the switch circuit (2) is turned on according to the control command.
Control signal generation circuit for outputting control signal to turn off (3)
And a control device (4) that outputs the control command to the control signal generation circuit (3) and the DC power supply device (1), and turns on and off the switch circuit to set a predetermined duty ratio ( A charging device for a secondary battery that charges a secondary battery with the pulse current of Q), comprising a temperature measuring unit (6) for measuring a battery temperature (T) or an ambient temperature of the secondary battery, The device (4) includes a voltage measuring unit (401) for measuring the voltage of the secondary battery.
And a calculating means (402) for measuring a voltage (Von) during the energization period of the pulse current and a voltage (Voff) during the non-energization period of the pulse current to obtain a difference voltage (Vd) between the two voltages. When the difference voltage (Vd) is smaller than the maximum allowable difference voltage (Vur), the secondary battery is determined to be in a normal state, and the difference voltage (Vd) is equal to or larger than the maximum allowable difference voltage (Vur). A battery state determination means (404) for determining that the secondary battery is in an abnormal state, and whether the battery temperature (T) or the ambient temperature of the secondary battery is within a set temperature range (T1 <T <T2). Temperature determining means (405) for determining whether or not the battery state determining means determines that the secondary battery is in a normal state, and the temperature determining means determines whether the battery temperature (T) or ambient temperature is Set temperature range (T1 <T <
When it is determined that the current is within T2), the duty ratio (Q) and the current value (I) of the pulse current (I) are set in a predetermined inverse proportional relationship with respect to the change in the difference voltage (Vd). The battery temperature (T) or the ambient temperature is higher than the set temperature range (T1 <T <T2) when the battery temperature (T) is higher than the set temperature range (T1 <T <T2). According to T), the temperature is corrected so that the duty ratio (Q) is increased and charging is performed, and the temperature determination means causes the battery temperature T to fall within a set temperature range (T1).
If it is determined that the temperature is lower than <T <T2), the temperature is corrected so as to reduce the duty ratio (Q) according to the battery temperature (T) or the ambient temperature, and charging is performed. A first control command generation means (406) for outputting the control command to the control signal generation circuit (3) and the DC power supply device (1); and the battery state determination means when the secondary battery is in an abnormal state. During the determination, the duty ratio is smaller than the minimum duty ratio of the duty ratio (Q) determined by the first control command generating means, and more than the current value determined by the first control command generating means (406). Second control command generation means (407) for outputting the control command to the control signal generation circuit (3) and the DC power supply device (1) so that charging is performed using a pulse current having a large current value. Charging device for a secondary battery characterized by comprising a charging completion confirmation means for stopping the operation of the control device to confirm the completion of charging (408). 9. The charging completion confirmation means (408) is configured not to perform a charging completion operation or to ignore the detection of charging completion until a predetermined time has elapsed after the start of charging. The charging device for a secondary battery according to claim 6, 7, or 8.