JP3693000B2 - Secondary battery charge control method and electric device using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charging control method for a secondary battery, and more particularly to a charging control method for controlling charging by detecting the temperature and voltage of a secondary battery during charging.
[0002]
[Prior art]
Secondary batteries typified by nickel hydride secondary batteries or nickel cadmium secondary batteries have been widely put into practical use as operating power sources for various equipment systems such as portable telephones and portable photographing machines. In recent years, a large current can be discharged and it is also used as a power source for electric tools and vacuum cleaners.
[0003]
By the way, charge and discharge are the main functions of the secondary battery, and a conventional charge / discharge control method will be described below. FIG. 6 is a circuit block diagram in an actual embodiment of the charge control method. Reference numeral 1 denotes a charger, which is a charge control incorporating an input power source 2, a constant current circuit 3, a battery voltage detection means 4 and a calculator 5 (microcomputer). The circuit 6 and the DC power supply 7 that is the power supply of the arithmetic unit 5 are employed. The constant current circuit 3 can obtain the output of the computing unit 5 and output ON / OFF of charging and a plurality of types of constant current values. A battery pack 8 includes a plurality of secondary batteries 9 connected in series or in parallel, and a positive electrode and a negative electrode are connected so that the output of the constant current circuit 3 of the charger 1 is applied. Further, there is a temperature detection means 10 (generally a thermistor) that is disposed in the vicinity of the secondary battery 9 and detects the temperature at the time of charging and standby of the secondary battery 9, and the DC power supply 7 and the dividing resistor of the charger 1. 11 is connected. The signal from the temperature detection means 10 is configured to be transmitted to the calculator 5 of the charge control circuit 6. Charging of the secondary battery 9 is normally performed at a constant current by the constant current means 3, and the temperature detection means 10 for detecting the battery temperature and the battery voltage detection means 4 for detecting the battery voltage are charged. It is taken in and controlled by means 6. FIG. 7 is a characteristic diagram of battery temperature (T) change and battery voltage (V) change during charging, explaining the operation. When the charging control circuit 6 detects that the secondary battery 9 is connected to the charger 1, it is determined whether the battery voltage V and the battery temperature T are suitable for charging, and if so, charging is started. When it is not suitable, a current much smaller than the normal charging current is supplied, the battery voltage V rises to a predetermined voltage, and a standby state is entered until the battery temperature T cools to a predetermined temperature (not shown). During normal charging, the battery voltage V and battery temperature T of the secondary battery 9 are checked at any time to detect a fully charged state such as a -ΔV value or dT / dt (FIG. 7 shows nickel cadmium based on the -ΔV value). (The case of secondary battery charge control is shown). If the fully charged state can be detected, the normal charging is completed and the process proceeds to trickle charging to replenish the self-discharge. The purpose of this trickle charge is to compensate for the capacity that cannot be fully charged when the battery temperature T rises when the charge is completed. As for battery discharge control, there are various discharge controls such as detecting the battery voltage T and battery temperature V and stopping the operation when a constant voltage value is set so as not to cause overdischarge, or displaying the remaining amount. Various measures have been devised for charge / discharge control in order to extend the life of the battery, for example, by stopping the charge when the battery temperature is detected and exceeding a certain temperature.
[0004]
[Problems to be solved by the invention]
However, in the conventional configuration described above, in a device with a large amount of discharged electricity such as a vacuum cleaner using a large number of batteries, the temperature of the secondary battery immediately after discharging is 50 ° C. or higher, and the normal charging is performed as it is. Then, even at the end of charging, the temperature of the battery does not cool and charging is terminated at a high temperature, resulting in a significant shortage of charging. When charging and discharging in an insufficiently charged state are repeated, there is a problem that the amount of electricity that can be gradually charged (hereinafter referred to as charging capacity) decreases and the usage time for discharging becomes short. In addition, it takes a considerable amount of time for the battery to cool down to a temperature at which it can be fully charged. Therefore, when waiting for the battery to reach that temperature, the time from when the secondary battery is set in the charger until the battery is fully charged. When the user intends to use it, the battery becomes uncharged at the time when the user wants to use it.
[0005]
The present invention has been made in order to solve such problems. Even when the amount of discharged electricity is large and the battery temperature immediately after discharge is high, normal charging is completed in a short time, and charging is compensated by compensating for insufficient charging. An object of the present invention is to provide a secondary battery charge control method capable of preventing an early decrease in charge capacity due to repeated charging and discharging in an insufficient state.
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a current supply means for supplying a charging current to a secondary battery, a temperature detection means for detecting the temperature of the battery, a voltage detection means for detecting the voltage of the battery, and the temperature detection. Full charge is detected by temperature change (dT / dt) per unit time of battery temperature of the means, or full charge is detected by negative potential difference (-ΔV value) after the voltage detection means detects the peak voltage And control means for controlling the charging, and when the temperature of the secondary battery is lower than the preset normal charging start temperature of the secondary battery, the process proceeds to the normal charging, the full charging is detected and the normal charging is terminated. If the temperature of the secondary battery is equal to or higher than the preset normal charging start temperature of the secondary battery, it waits until the temperature reaches the normal charging start temperature or lower. migrated after full charge detection, the power Temperature Wait to stop charging until reaching the additional charging start temperature set in advance, performs additional charging one or more times of charging at a charging current of normal charging from the time it reaches the additional charging start temperature, The secondary battery charging control method is characterized in that the additional charging start temperature is set to a value lower than the normal charging start temperature in normal charging, whereby charging is performed by charging the secondary battery at a high temperature. Charging capacity can be compensated for, and charging can be performed sufficiently, and charging capacity is prevented from prematurely decreasing due to repeated charging / discharging in a state of insufficient charging, and charging is waited until the battery cools even when the battery temperature is high. Therefore, normal charging can be completed in a short time.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is a current supply means for supplying a charging current to the secondary battery, a temperature detection means for detecting the temperature of the battery, a voltage detection means for detecting the voltage of the battery, and the temperature detection. Full charge is detected by temperature change (dT / dt) per unit time of battery temperature of the means, or full charge is detected by negative potential difference (-ΔV value) after the voltage detection means detects the peak voltage And control means for controlling the charging, and when the temperature of the secondary battery is lower than the preset normal charging start temperature of the secondary battery, the process proceeds to the normal charging, the full charging is detected and the normal charging is terminated. If the temperature of the secondary battery is equal to or higher than the preset normal charging start temperature of the secondary battery, it waits until the temperature reaches the normal charging start temperature or lower. migration was fully after charge detection, battery temperature Together but waits to stop charging until reaching the additional charging start temperature set in advance, performs additional charging one or more times of charging at a charging current of normal charging from the time it reaches the additional charging start temperature, the Since the secondary battery charge control method is characterized in that the additional charge start temperature is set to a value lower than the normal charge start temperature in normal charge, the secondary battery can be charged by charging at a high temperature. It is possible to fully charge because it can compensate for the capacity not to be charged, and to prevent the premature decrease of the charge capacity due to repeated charge and discharge in the insufficient charge state, and to wait for the battery to cool down even when the battery temperature is high Since there is no need, normal charging can be completed in a short time.
[0008]
In addition , the capacity of the secondary battery that cannot be fully charged by charging at high temperature is compensated accurately without overcharging, and the charging efficiency of additional charging is improved more effectively by lowering the temperature at the start of additional charging. Since additional charging is possible, the charging capacity can be prevented from being quickly reduced due to repeated charging and discharging under insufficient charging conditions, and even when the battery temperature is high, it is not necessary to wait for the battery to cool down, so normal charging can be completed in a short time. Can be made.
[0009]
The invention according to claim 2 of the present invention is an electric device that is charged using the method for controlling charging of a secondary battery according to claim 1, and in a short time even when the amount of discharged electricity is large and the battery temperature immediately after discharge is high. By completing normal charging and compensating for insufficient charging, it is possible to provide an electric device that can prevent an early decrease in charging capacity due to repeated charging and discharging in an insufficient charging state.
[0010]
【Example】
(Example 1)
A first embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same component as a prior art example, and description is abbreviate | omitted.
[0011]
FIG. 1 is a circuit block diagram in an actual embodiment of a charging control method for a secondary battery according to the present invention. Reference numeral 1 denotes a charger, an input power source 2, a constant current circuit 3, a battery voltage detection means 4 and an arithmetic unit 5. A configuration including a charge control circuit 6 which is a charge control means incorporating a (microcomputer) and a DC power source 7 which is a power source thereof is adopted. The constant current circuit 3 can obtain the output of the computing unit 5 and output ON / OFF of charging and a plurality of types of constant current values. A battery pack 8 includes a plurality of nickel hydride secondary batteries or secondary batteries 9 which are nickel cadmium secondary batteries connected in series or in parallel, and the output of the constant current circuit 3 of the charger 1 is applied. As shown, the positive electrode and the negative electrode are connected. Further, there is a temperature detection means 10 that is disposed in the vicinity of the secondary battery 9 and detects the temperature at the time of charging and standby of the secondary battery 9, and is connected to the DC power source 7 of the charger 1 via the dividing resistor 11. Yes. The signal from the temperature detecting means 10 is transmitted to the calculator 5 of the charging control circuit 6. Obtaining information from the battery voltage detection means 4 and the battery temperature detection means 10, the calculator 5 in the charge control circuit 6 starts and ends normal charge (detects full charge), and performs additional charge after full charge detection. Then, the transition of trickle charge after the additional charge (not shown, not described) is determined, and the charge control circuit 6 outputs the constant current circuit 3 to the constant current circuit 3. The constant current circuit 3 generates a constant current corresponding to each charge state by the signal. The secondary battery 9 is charged. Further, the DC power source 7 is connected to a display means (hereinafter referred to as display LED) 12 constituted by an LED for indicating that charging is in progress, and the charging state is displayed by a signal from the charging control circuit 6.
[0012]
An embodiment will be described with reference to a charging operation explanatory diagram shown in FIG. 2 for a secondary battery charging control method with the circuit configuration shown in FIG.
[0013]
First, the secondary battery pack 8 is connected to the charger 1. Therefore, the charge control circuit 6 determines whether the temperature TA of the secondary battery 9 of the battery pack 8 is higher than the preset normal charging start temperature T0 from the signal of the temperature detection means 10. If the secondary battery 9 temperature TA is equal to or lower than the normal charging start temperature T0, the charger 1 shifts to normal charging and charges the battery pack 8 with the charging current IA0. When the temperature TA is high, the charger 1 supplies a very small current (about 1/5 to 1/10) from the constant current circuit 3 compared to the current IA0 during normal charging until charging is possible. It will wait in a state (not shown). Here, when the battery temperature TA is lowered and the normal charging start temperature T0 is reached, normal charging is started, but T0 is set to a temperature higher than room temperature (for example, 50 ° C.) in order to shorten the charging standby time as much as possible. . When normal charging is started when T0 is reached, the charging control circuit 6 determines that it is necessary to execute preset additional charging to compensate for insufficient charging because the secondary battery is charged at high temperature, and battery voltage detection means 4 detects -ΔV0 of the battery voltage VA of the secondary battery 9 and stops charging until the battery temperature TA reaches a preset additional charging start temperature T1 after the normal charging is completed, and reaches T1 The additional charging is performed with the charging current IA0 from the time point. At this time, when the charging current during standby from the end of normal charging to the start of additional charging is set to 0, if a trickle current is applied to a battery near the fully charged state, the battery temperature tends to rise somewhat. For this reason, the battery temperature is not easily lowered and it is prevented from taking a long time for additional charging. In order to increase the charging effect of the additional charging, the additional charging start temperature T1 needs to be charged at a low temperature rather than immediately after the end of the normal charging where the battery temperature TA is high. Therefore, the additional charging start temperature T1 is higher than the normal charging start temperature T0. The temperature is set to a low temperature (for example, 35 ° C.) close to normal temperature. The number of executions of additional charging is the temperature level of the minimum battery temperature at which the negative temperature change (-dT / dt) per unit time of the battery calculated by the calculator 5 from the signal of the temperature detection means 10 during normal charging becomes 0 Is determined by how many degrees Celsius is. For example, if the battery temperature minimum value level is TA3 or higher, additional charging is performed four times. If the level is TA2 or higher and lower than TA3, then three additional chargings are performed. Once. This is because even if the charging start temperature is the same, the battery temperature minimum level fluctuates due to the influence of the ambient temperature during charging and the new and old state of the battery itself. The higher the battery temperature minimum level, the higher the average battery temperature during charging. For this reason, it is estimated that the amount of charge that can be charged during normal charging of the battery is smaller, and therefore it is necessary to perform more additional charging. In addition, in order to prevent the battery from being overcharged, the termination determination in the case where the additional charging is performed two or more times is normally terminated when the battery voltage VA reaches the peak, and only the final additional charging is terminated at −ΔV1. ing. This -ΔV1 value is set to be larger than the -ΔV0 value during the normal charging because it is necessary to push the charging amount deeper in the final round. The display LED 12 is turned on during normal charging, displays to the user that charging is in progress, turns off when normal charging ends, and continues to turn off during subsequent additional charging. The purpose of this indicator LED is to inform the user whether or not the battery can be used, so that it is lit until the additional charge is completed, although about 90% of the battery capacity can be fully charged with normal charging. This is because the user determines that the user has not been charged yet and cannot use it and waits for a long time, which makes it very difficult to use as a charger. For the case where the charging start temperature is low, the details are omitted because of the operation of performing quick charging as in the prior art and shifting to trickle charging.
[0014]
In the above description, the number of executions of additional charging is determined based on the case where the battery temperature TA is determined based on the temperature level of the minimum battery temperature at which the negative temperature change (−dT / dt) per unit time becomes zero. As shown by 2, it can also be determined by the peak level near the full charge of the battery voltage VA. As with the minimum battery temperature level, the battery voltage VA peak level when fully charged varies depending on the ambient temperature during charging and the new and old battery conditions. The higher the battery voltage peak level, the higher the battery voltage peak level. This is because there is a correlation that the amount of charge that can be charged while the average battery temperature is high and the battery can be charged during normal charging is smaller. For example, in the case of the battery voltage peak level, if the battery voltage peak level is equal to or lower than TV3, additional charging is executed four times. If the level is equal to or higher than TV3 and lower than TV2, the additional charge is performed three times. 1 time if TV1 or more.
[0015]
Further, in this embodiment, additional charging is performed depending on the temperature level of the minimum battery temperature at which the negative temperature change (−dT / dt) per unit time of the battery temperature TA becomes 0 or the peak level near the full charge of the battery voltage VA. The example of setting the number of executions has been described. However, if the battery is charged at a high temperature and becomes insufficiently charged, the charging time is also shortened. Therefore, it is possible to set the number of additional charging executions in the time required for normal charging. A similar effect is obtained in that the shortage of battery capacity is compensated to prevent an early decrease in battery capacity.
[0016]
(Example 2)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In addition, about the structure of the charging control apparatus of a secondary battery for implement | achieving a present Example, and control until it starts additional charge through a standby mode from a normal charge, 1st Example of this invention, a component, and control Since the method is the same, the description is omitted.
[0017]
FIG. 3 is an explanatory diagram of the charging operation of the charging control method of this embodiment. The secondary battery 9 in a high temperature state reaches a normal charging start temperature T0 set in advance, and charging starts. The charging control circuit 6 determines that additional charging is necessary (not shown) and sets an additional charging completion battery voltage level VAP ′ with respect to the peak voltage VAP of the battery voltage VA for determining completion of additional charging. The peak voltage VAP of the battery voltage VA during the additional charging tends to gradually increase as the capacity of the battery approaches 100% after additional charging is performed a plurality of times. Therefore, each time additional charge is executed, the peak voltage VAP generated by the additional charge is compared with the additional charge completion battery voltage level VAP ′, and the additional charge is executed until VAP ≧ VAP ′. Accordingly, even a battery that is normally charged in a high temperature state can be sufficiently charged to nearly 100%, so that it is possible to prevent an early decrease in battery capacity due to repeated use of an undercharged battery.
[0018]
(Example 3)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In addition, about the structure of the charging control apparatus of a secondary battery for implement | achieving a present Example, and control until it starts additional charge through a standby mode from a normal charge, 1st Example of this invention, a component, and control Since the method is the same, the description is omitted.
[0019]
FIG. 4 is an explanatory diagram of the charging operation of the charging control method of the present embodiment. The secondary battery 9 in a high temperature state reaches a normal charging start temperature T0 set in advance, and charging starts. The charge control circuit 6 determines that additional charging is necessary (not shown) and presets a peak voltage increase difference ΔVP of the battery voltage VA for determining completion of additional charging. The peak voltage VP of the battery voltage VA gradually increases while the additional charging is performed a plurality of times. However, the rate of increase of the peak voltage VP (ΔVP1 ≧ ΔVP2 ≧ ΔVP3...) Gradually increases as the battery capacity approaches 100%. It tends to decrease. Accordingly, each time additional charging is performed, the peak voltage level generated in the previous additional charging is compared with the peak voltage level detected this time, and the additional charging is terminated when ΔVP3 ≦ ΔVP. Accordingly, even a battery that is normally charged in a high temperature state can be sufficiently charged to nearly 100%, so that it is possible to prevent an early decrease in battery capacity due to repeated use of an undercharged battery.
[0020]
(Example 4)
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. In addition, about the structure of the charging control apparatus of a secondary battery for implement | achieving a present Example, and control until it starts additional charge through a standby mode from a normal charge, 1st Example of this invention, a component, and control Since the method is the same, the description is omitted.
[0021]
FIG. 5 is an explanatory diagram of the charging operation of the charging control method of the present embodiment. The secondary battery 9 in the high temperature state reaches the preset normal charging start temperature T0 and charging starts. The charge control circuit 6 determines that additional charging is necessary, and the number of executions of additional charging is the negative temperature change per unit time (−) calculated by the calculator 5 from the signal of the temperature detection means 10 during normal charging. In addition to determining the temperature level of the minimum battery temperature at which dT / dt) is 0 (not shown), an additional charging end temperature level T2 of the battery temperature TA for determining completion of additional charging is set. Set. During additional charging, the battery temperature TA during additional charging tends to gradually increase as the capacity of the battery approaches the fully charged capacity. Therefore, the additional charging end temperature level T2 is set in advance to the battery temperature limit value immediately before overcharging, and the battery temperature TA reaches this additional charging end temperature level T2 every time additional charging is performed. By setting this point, the battery does not reach overcharge and can be sufficiently deeply charged.
[0022]
【The invention's effect】
By the present invention lever, it is possible to perform sufficient charge because it can be compensated accurately without being the capacity that can not be charged at the charging at a high temperature of the secondary battery to overcharging, charging and discharging in the charging insufficiency As a result, it is possible to complete normal charging in a short time since it is not necessary to wait until the battery cools even when the battery temperature is high. The Ri by to such control, can be used when you want to use immediately, good charging usage time of the discharge by the performed extend closer to 100% when placed time until use Can provide a charger.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram showing the configuration of a charge control device for a secondary battery according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of the charge operation of the charge control method. FIG. 4 is an explanatory diagram of charging operation of the charging control method according to the third embodiment of the present invention. FIG. 5 is an explanatory diagram of charging operation of the charging control method according to the third embodiment of the present invention. Charge operation explanatory diagram of control method [FIG. 6] Circuit block diagram of charge control showing conventional example [FIG. 7] Charge operation explanatory diagram [description of symbols]
3 Constant current circuit 4 Battery voltage detection means 6 Charge control circuit (charge control means)
9 Secondary battery 10 Temperature detection means 12 Charge display means

Claims (2)

Current supply means for supplying a charging current to the secondary battery, temperature detection means for detecting the temperature of the battery, voltage detection means for detecting the voltage of the battery, and the temperature per unit time of the battery temperature of the temperature detection means A control unit that detects full charge by a change (dT / dt), or detects full charge by a negative potential difference (−ΔV value) after the voltage detection unit detects a peak voltage, and controls charging; When the temperature of the secondary battery is lower than the preset normal charging start temperature of the secondary battery, the process proceeds to normal charging, the full charging is detected and the normal charging is terminated, and the temperature of the secondary battery is preset. and if the normal or charge start temperature of the secondary battery, and wait until the normal becomes less charging start temperature, if below normal charge starting temperature, first migrated after full charge detection to the normal charging, the battery temperature Additional charging start temperature set in advance Wait stop charging until reaching the, performs one or more times an additional charge for charging with a charging current of normal charging from the time it reaches the additional charging start temperature, the additional charge start temperature is usually charged A charge control method for a secondary battery, characterized in that it is set to a value lower than the normal charging start temperature . An electric device that is charged using the charge control method for a secondary battery according to claim 1 .

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