JP2987384B2 - Rechargeable battery charge control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control method for a secondary battery, and more particularly to a method for performing a predetermined charge control operation in accordance with the magnitude of a battery voltage during charging.

[Related Art] Generally, a rechargeable battery such as a nickel-cadmium battery repetitively overcharges greatly reduces the cycle life of the battery. Therefore, it is necessary to accurately detect a full charge state and control charging to shift to auxiliary charging. Become.

To such requests, utilizing the fact that the battery voltage with the progress of charging is increased as indicated by the solid line in FIG. 2, when it is detected that the battery voltage during charging has reached a set value V ₁ predetermined control operation , A method of performing a steady charging control operation has been proposed.

Further, by utilizing the fact that the surface temperature of the battery rises as the charging proceeds, the charging is forcibly stopped when the temperature rises beyond the set value, so that the above-described charge control by detecting the battery voltage is appropriately performed. Even in the case where the charging is not performed, a charging control method capable of appropriately detecting a charging abnormality of the battery and preventing overcharging is also performed.

[Problems to be Solved by the Invention] By the way, at the time of rapid charging with a large current, as shown by the dashed line in FIG. 2, the internal gas pressure of the battery rises sharply at the end of charging and the ambient temperature Tb decreases. Its value increases. Therefore, if charging is continued under the same conditions as when the temperature Tb is high despite the remarkable decrease in the cycle temperature Tb, the gas valve provided in the secondary battery is activated, and the electrolyte inside the battery squirts out. Is caused, and there is a strong possibility that the battery itself is deteriorated.

The present invention has been made based on the above-described problem, and by detecting an ambient temperature during charging and controlling charging in accordance with the temperature, appropriate charging control can be performed regardless of the ambient temperature. It is an object to provide a charge control method that can be performed.

Another object of the present invention is to provide a charge control method capable of terminating charging without deteriorating a battery even when charging is performed under extremely low ambient temperature conditions.

[Means for Solving the Problems] The charge control method according to the present invention provides a method for controlling a battery voltage of a secondary battery.
When Va reaches the set value V ₁ and enters the control of the charged amount, the ambient temperature Tb of the battery is measured, and the narrowing rate of the charged amount is corrected according to the magnitude of the measured value Tb. .

The present invention further provides a set value V ₁ of the battery voltage Va as described above, while correcting in response to a change in ambient temperature Tb, subsequent charging amount correction battery voltage Va has reached the set value V ₁ was, ambient temperature When it is detected that Tb is Shitamawa' the lower limit temperature T ₁ of, for example, about 0 ° C., then it was subjected to either rapidly narrowing immediately stop performing have rapidly charged to it, configured so as to shift the auxiliary charge doing.

[Effect "by the above structure, by the cell voltage at time t ₁ reaches the set value V _1, it can be determined that the predetermined charging is being performed in the secondary battery.

At this time, if it is further detected that the ambient temperature Tb is a low temperature such as 0 ° C. or less, it is a normal charging end time.
to terminate the charge in a short t ₂ 'than t _2, it is corrected to squeeze than normal charging. This prevents the internal gas pressure of the secondary battery from unnecessarily increasing.

[Embodiment] Hereinafter, the present invention will be described based on an example in which the present invention is applied to an electric shaver. However, the present invention is not limited to this, and the same applies to various small electric appliances including a charging device alone or a charging unit in a power supply portion. Of course, it can be implemented.

In the electric shaver embodying the present invention, as shown in FIG. 3, an outer blade 1 is detachably mounted on an upper portion of a main body case 2, and an inner blade 3 is slidably disposed inside the outer blade 1. . Further, inside the main body case 2, a motor 4 for reciprocatingly driving the inner blade 3, a secondary battery 5 for supplying rotational driving power to the motor 4, a charge control for the secondary battery 5, An electric circuit 6 for performing various controls such as rotation control is housed. Further, a knob 8 of a slide switch 7 for regulating the timing of energizing the motor 4 is provided at the center of the front of the main body case 2.
A motor rotation display section 9 for displaying the rotation control state of the motor and a battery capacity display section 10 for displaying a change in the battery capacity are provided. Further, a power cord 11 having a power plug provided at a tip thereof is detachably provided at a lower portion of the main body case 2 so that the motor 4 can be directly driven by a commercial AC power supply 12 in addition to charging the secondary battery 5.

FIG. 4 is a block diagram schematically showing the entire electric circuit 6 built in the main body case 2 described above, and includes a drive circuit 13 for the motor 4, a detection circuit 14 for performing various detection operations on the drive circuit 13, and The control circuit 15 includes a control circuit 15 that generates a predetermined signal in response to the input of a detection signal from the detection circuit 14, and a display circuit 16 that performs display corresponding to the state of the motor drive circuit 13.

The motor drive circuit 13 performs charging by converting the commercial AC power supply 13 into a predetermined charging voltage by the inverter circuit 17 and then applying the charging voltage to the secondary battery 5 such as a nickel-cadmium battery. The output voltage from the secondary battery 5 is applied to the motor rotation control unit 18 via the switch 7 to perform rotation control for maintaining the rotation speed of the motor 4 at a constant value. At 9, the state in which the rotation control is being performed is displayed.

The detection circuit 14 includes an AC input detection unit 20 and a load drive timing detection unit 21 so that the drive mode of the motor drive circuit 13 can be detected.According to detection signals from both the detection units 20 and 21, the AC input is detected. When it is detected that the motor is driven and the motor is not driven, the operation of the control circuit 15 enters a “charging mode” shown in detail in FIGS. 5 and 1.

The present invention is characterized by the configuration of the charging mode, and includes a battery voltage detecting unit 22 that measures a value of a battery voltage.
And a battery temperature detector 23 for measuring the surface temperature of the secondary battery 5
In addition to the output from the inverter circuit 17 and the battery capacity display unit, in conjunction with the input of the detection signal output from the periodic temperature detection unit 24 for measuring the temperature around the battery during charging,
10 controls.

The battery capacity display unit 10 includes six light emitting diodes 25a to 25f. By increasing or decreasing the number of light emitting diodes 25, the lighting position of each light emitting diode 25 is 0 to 100%.
Digital display of battery capacity every 20%. Further, each light-emitting diode 25 is connected to an output terminal of a shift register 26 provided in the control circuit 15, and always saves the contents of the shift register 26, and shifts the charge timing and the discharge timing in the opposite direction, so that the The change in the battery capacity can be displayed continuously over the entire period in which the razor is used.

By the way, the display of the battery capacity and the control of the amount of charge at the time of charging are basically based on the time using the timer 27. For example, if the charging is terminated in about 30 minutes the start of the rapid charge battery capacity from time t ₀ in a state of "0", performs a shift of 1 bit shift register 26 at the output pulse from counter 28 The counter 28 is set to count up in 7 minutes by a pulse signal output from the 7-minute timer 29. Then, the steps in FIG.
After turning on the light emitting diodes 25a and 25b corresponding to "0 and 20% display" with almost no capacity at 50, steps 51 to 54
The number of light-emitting diodes 25 is increased every 7 minutes, and all the light-emitting diodes 25 are lit to perform 100% display in step 54, and at the same time, the output control unit
A signal is sent to 30.

The output control unit 30 regulates the operation of the inverter circuit 17, and maintains the output from the inverter circuit 17 at or near 100% during fast charging. In conjunction with this, the output of the inverter circuit 17 is reduced three minutes after the input of the signal,
By making a transition to the supplementary charging in step 55, the quick charging is configured to end at the maximum 31 minutes after the start of the charging in step 50.

Here, even during the control period by the timer mode A, the detection mode B is entered at minute time intervals to perform various detection operations, and if the detection satisfying the setting conditions described later is not performed, the operation returns to the original timer mode A. However, when the detection is performed, control for shifting to the control mode C is performed.

That is, the battery temperature output from the battery temperature detection unit 23
The magnitude of the signals corresponding to Ta, as compared to the set temperature T ₂ in the first comparing section 31a, when it is determined in step 56 that the battery temperature Ta is higher than the set temperature T _2, the first comparator unit A set signal is sent from 31a to the output control unit 30, and the inverter circuit 17 is immediately shifted to the auxiliary charging state in step 55. In this case, the display on the capacity display unit 10 is the first comparison unit 31.
a, by switching the timer 27 for counting up the counter 28 from the 7-minute timer 29 to the 1-minute timer 32, the display state in the timer mode A is taken over, and the light emitting diode
The increase in the number of lighting of 25 is reduced every minute. For example, after performing the display of 40% in step 51, the determination in step 56 is YE 30 minutes after the counter 28 has completed the half counting, 3 minutes and 30 seconds later.
If the count reaches S, the remaining count of the counter 28 is counted by the 1-minute timer 32 over 30 seconds, thereby completing the step.
It moves to the 60% display of 59, and after that, the number of lighting of the light emitting diode 25 is increased by one every minute, and the step is performed.
The 61 "100% display" prevents the operator from feeling uncomfortable by suddenly shifting from a small percentage display to a full charge display.

If the battery temperature detection in step 56 is NO, the output Va from the battery voltage detection unit 22 is further compared with the second comparison unit 31.
proceeds to step 62 of comparing set voltages V ₁ and in terms of b.

The set temperature V ₁ is, for example, _{one such} that even when the battery voltage curve changes from the normal temperature state of the ambient temperature Tb shown by the thick line in FIG. 2 to the low temperature state shown by the thin line, it can be detected at substantially the same time t _1. The temperature is continuously corrected such that the temperature rises by several mV at a drop of 1 ° C. per cell. Therefore, when the battery voltage Va in such step 62 that exceeds V ₁ of the second view is determined at time t _1, the charge of the same, predetermined volume regardless of changes in ambient temperature Tb in the secondary battery 5 Therefore, the timer for counting up the counter 28 is switched from the seven-minute timer 29 to the three-minute timer 33. At the same time proceeds to step 63, it is compared with the output signal from the ambient temperature detection unit 24 in the third comparing unit 31C set temperature T _1. Here, when it is determined that the ambient temperature Tb is higher than 0 ° C., for example,
Thereafter, the display increasing speed of the battery capacity display section 10 is increased to about twice that in the case of the timer mode A, and the control for limiting the quick charging time to about half of that in the case of the timer mode A is performed. Turning to supplementary charging step 55 to t _2.

On the other hand, if the determination in step 63 is YES, the battery voltage Va is set to the set value for the display of the battery capacity.
Performed similarly using 3 minute timer 33 and when it exceeds V _1, but for the output control of the inverter circuit 17, by sending a reset signal to the direct output control section 30 from the third comparator unit 31C Regardless of the stage at which the display of the battery capacity display unit 10 is at any time, the process shifts to the supplementary charging at the step 55 at a time t ₂ ′ three minutes after the determination at the step 63 is made.

Although the control for reducing the charging time is performed in the control mode C described above, the control for reducing the charging current may be performed with the same time as in the timer mode A. Further, the control of the charge amount and the display of the battery capacity may be made to match. Further, instead of the two-stage charge correction for the change in the ambient temperature Tb, a continuous correction may be performed.

Further, without performing the correction of the set value V ₁ of the battery voltage Va in correspondence with changes in ambient temperature Tb, after the detection of the set value V _1,
Only the charge amount correction corresponding to the measured value of the ambient temperature Tb may be performed.

The control circuit 15 uses a one-chip microcomputer,
The same operation as described above can be performed by a program.

[Effect of the Invention] As described above, the present invention detects the ambient temperature Tb and simultaneously corrects the charge control amount by controlling the charge amount by detecting the battery voltage Va.
Regardless, the appropriate charge control can be performed.

When it is detected that the ambient temperature Tb is extremely low,
By making the correction of the charge amount sufficiently large, even when quick charge is performed at a low temperature, deterioration of the secondary battery 5 due to the operation of the gas valve is prevented beforehand, and the battery life is extended.

Furthermore, since the battery surface temperature Ta decreases due to the decrease in the ambient temperature Tb, even if the charging abnormality detection that monitors the change in the battery surface temperature Ta does not work sufficiently, the auxiliary charging is surely performed. It has many advantages, including the ability to migrate.

[Brief description of the drawings]

1 and 2 are diagrams for explaining a method according to the present invention. FIG. 1 is a flowchart of control, and FIG.
It is a graph explaining the criterion in the detection mode of the figure. 3 to 5 show an example in which the present invention is applied to an electric shaver, FIG. 3 is a partially cutaway front view showing an appearance state, and FIG. 4 is a block diagram showing a schematic configuration of an electric circuit. FIG. 5 is an explanatory diagram showing the operation of the control circuit of FIG. 5 Secondary battery, 14 Detection circuit, 15 Control circuit, 17 Inverter circuit, 22 Battery voltage detection section, 23 Battery temperature detection section, 24 Ambient temperature detection section.

Claims (1)

(57) [Claims] 1. Battery voltage of a secondary battery (5) during charging
Measured Va, when the measured value reaches the set value V _1, a charging control method for applying a predetermined narrowing it subsequent charge amount, when the control of the charge amount by the detection of the battery voltage Va as described above, the two with measuring the ambient temperature Tb of the next cell (5), the set value V ₁ mentioned above, while performing correction to increase in response to lowering of the ambient temperature Tb, the lower limit temperature T ₁ of the ambient temperature Tb is preset A charge control method for a secondary battery, characterized in that when it is detected that the charge is lower, the quick charge is immediately stopped or rapidly narrowed down to shift to an auxiliary charge.