JP3945050B2 - Charger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charger for charging a secondary battery such as a nickel cadmium battery.
[0002]
[Prior art]
The structure of the conventional charger will be described with reference to FIGS.
[0003]
In FIG. 12, it has a transformer 2 whose primary side is connected to the commercial power source 1, a diode bridge 3 connected to the secondary side of the transformer 2 for rectifying operation, and a capacitor 4 for smoothing the current, A DC voltage generated by the action of the diode bridge 3 and the capacitor 4 is applied to the secondary battery 6 via the constant current circuit 5. At this time, the voltage of the secondary battery 6 is measured by the voltage detection means 7, and a charging current having an optimum magnitude is selected according to the charge amount of the secondary battery 6 estimated from the transition, and the signal control means A signal is sent from 9 to the constant current circuit 5 so that a predetermined charging current is supplied to the secondary battery 6.
[0004]
There are the following methods for estimating the amount of charge.
[0005]
1. -ΔV detection method: The peak of the battery voltage during charging is detected, and when the amount of decrease in battery voltage -ΔV reaches the set value -ΔVx, it is estimated that the battery is fully charged.
[0006]
2. Temperature-controlled charging method: The battery temperature during charging is measured, and it is estimated that the battery is fully charged when the battery temperature T reaches a predetermined value or when the amount of decrease T-ΔT reaches a predetermined value.
[0007]
3. Timer method: The elapsed time from the start of charging is counted, and it is estimated that the battery is fully charged when a predetermined time has elapsed.
[0008]
When it is estimated that the battery is fully charged by the above method, in order to prevent the battery from being overcharged, a transition to trickle charge (charging at about 1/10 of the normal charging current) is performed. Or it was going to end charge.
[0009]
The above operation will be described with reference to FIG. FIG. 13 is a flowchart of a charger that uses both the -ΔV detection method and the timer method, and the operation of the temperature control charging method is the same as that of the -ΔV detection method, and is therefore omitted.
[0010]
The timer starts counting when the secondary battery 6 is connected to the charging terminal 10 in Step 1, and it is determined whether or not a predetermined time has elapsed in Step 2, and if it has elapsed, the process proceeds to trickle charging. If not, the peak value of the battery voltage from the start of charging to the present time is obtained in step 3. If the current voltage value is not equal to or higher than the peak value, the maximum value of the battery voltage is compared with the current value in step 4, and if the difference −ΔV is equal to or greater than the set value −ΔVx, it is determined that the battery is fully charged. If it transfers to charge and it is less than-(DELTA) Vx, normal charge will be performed. In step 5, it is determined whether or not the secondary battery 6 has been removed from the charging terminal 10, and if removed, the timer is reset and the charging is terminated.
[0011]
[Problems to be solved by the invention]
Usually, the charging voltage of the secondary battery 6 has a characteristic that it reaches a peak value before it is fully charged and then decreases again to settle to a constant value. When the battery voltage becomes a considerably large value during charging due to a change in the contact state between the battery 6 and the charging terminal 10 or noise, and the value is updated as a peak value, the peak value is erroneously determined at that point, and −ΔV Charging may be terminated by detection, and the amount of charge may be insufficient.
[0012]
The present invention is intended to solve the conventional problems as described above, and an object thereof is to eliminate insufficient charging of a battery.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention updates and stores a voltage detection means for detecting the voltage of a secondary battery and a peak value which is the maximum value of past detection values detected by the voltage detection means. and a counting means for said counting means, the current value of the voltage of the secondary battery measured by the analog-to-digital conversion, even if greater than said peak value stored, the peak value to the value in the case that big Without updating directly, the peak value is counted by one count of the accuracy of the analog-digital conversion and is added and updated, and if the count of the counting means is not updated for a predetermined time, the magnitude of the charging current is changed, or When the peak value is updated, for example, the counting means counts only one count to the peak value, so the peak value may be updated due to noise or the like. Peak value can be a voltage gradually thereafter so not only increased one count to reaffirm the peak value when that has increased, it is not erroneously determine the peak value.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
According to a first aspect of the present invention, a voltage detection means for detecting a voltage of a secondary battery, and a peak value which is a maximum value of past detection values detected by the voltage detection means is updated and stored. and a counting means for said counting means, the current value of the voltage of the secondary battery measured by the analog-to-digital conversion, even if greater than said peak value stored, the peak value to the value in the case that big Without updating directly, the peak value is counted by one count of the accuracy of the analog-digital conversion and is added and updated, and if the count of the counting means is not updated for a predetermined time, the magnitude of the charging current is changed, or When the peak value is updated, for example, the counting unit counts only one count to the peak value, so even if the peak value may be updated due to noise or the like, the charging is terminated. Click value can be a voltage gradually thereafter so not only increased one count to reaffirm the peak value when that has increased, it is not erroneously determine the peak value.
[0015]
The invention of claim 2, wherein the present invention was to vary the detection sampling period of voltage of the secondary battery from the charge start immediately after start of charging after a predetermined time has elapsed, a large voltage change immediately after the start of charging In this case, the detection sampling period is shortened, and when the voltage change becomes small after a predetermined time, the detection sampling period is lengthened, so that the battery voltage can be accurately measured at any time. The battery can be charged without misjudging the battery, so that it is possible to eliminate insufficient charging of the battery.
[0016]
According to a third aspect of the present invention, there is provided a voltage detecting means for detecting the voltage of the secondary battery, an amplifying means for amplifying the voltage of the secondary battery, the voltage detecting means, and the past detected by the amplifying means. Counting means for updating and storing each peak value, which is the maximum value of the detected values, and the counting means measures the current value of the voltage of the secondary battery and the amplified voltage measured by analog-digital conversion. Even if both of the current values of the secondary battery voltage are larger than the stored peak value, the peak value is not directly updated to the value when it is larger, and the peak value is counted by one count of analog-digital conversion accuracy. together with updates plus, if the peak value of the voltage detection means and the peak value both amplifying means said voltage detecting means and the amplifying means is not updated predetermined time, changing the size of the charging current Alternatively, charging is terminated, and the change can be accurately detected by the amplifying means even in a small voltage change range, and the peak time point that is the starting point of the end time of charging can be accurately detected. , It has the effect of fully charging and eliminating the lack of charging.
[0017]
【Example】
Example 1
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the part same as a prior art example, and description is abbreviate | omitted.
[0018]
A transformer 2 having a primary side connected to the commercial power source 1; a diode bridge 3 connected to the secondary side of the transformer 2 for rectifying operation; and a capacitor 4 for smoothing current; A DC voltage generated by the action of the capacitor 4 is applied to the secondary battery 6 via the constant current circuit 5.
[0019]
7 is a voltage detection means for detecting the voltage of the secondary battery 6, and stores the peak value of the voltage of the secondary battery 6 detected by the voltage detection means 7 by the peak value setting means 8 which is a counting means. . The peak value setting means 8 measures the voltage by 8-bit analog-digital conversion (hereinafter referred to as A / D conversion), and if the measured voltage is larger than the stored peak value, the stored peak value is incremented by +1. Count up.
[0020]
A charging current having an optimum magnitude is selected according to the amount of charge of the secondary battery 6 estimated from the transition of the voltage of the secondary battery 6, and a signal is sent from the signal control means 9 to the constant current circuit 5, The charging current is supplied to the secondary battery 6. The first timer 11 measures the absolute time that the battery 6 is connected to the charging terminal 10, and the second timer 12 counts a predetermined time shorter than the first timer 11.
[0021]
When the secondary battery 6 is connected to the charging terminal 10 in step 1, the counting of the first timer 11 is started. In step 2, it is determined whether or not the predetermined time T1 has elapsed. If so, it is determined that the battery is fully charged, a trickle charge flag is set, the charge current is changed, or the charge is terminated. If the predetermined time T1 has not elapsed, the magnitude of the current value of the secondary battery 6 and the peak value so far is determined by the peak value setting means 8 in step 3, and the current value of the voltage of the secondary battery 6 is determined. If it is less than the peak value, the count of the second timer 12 is started in step 4, and if the current value of the voltage of the secondary battery 6 is larger than the peak value, the peak value is set to the peak value setting means 8 in step 6. The A / D conversion accuracy is incremented by 1 and updated (for example, the hexadecimal value 69 is 1 count larger than the hexadecimal value 68), and the second timer 12 is reset. In step 5, if the second timer 12 has reached a predetermined time T2 from the peak time, it is determined that the battery has been fully charged and a trickle charge flag is set to change the magnitude of the charge current or the charge is terminated. .
[0022]
The operation of the above configuration is as follows.
[0023]
Even if the current value of the voltage of the secondary battery 6 is quite large due to some factor in Steps 3 and 6, the peak value is not directly updated to the value when the voltage is large, and the peak value is counted as one A / D conversion accuracy. Only count and update. When the peak value is directly updated to a large value as shown in FIG. 3A, the time point is erroneously recognized as a peak point, but the peak value is only counted by 1 count of A / D conversion accuracy as shown in FIG. When the voltage is counted and updated, the peak time can be re-recognized when the voltage gradually increases thereafter. The second timer 12 counts from the re-recognition time, and is sufficient when the predetermined time T2 has elapsed. Since the charging current can be supplied, the charging current is changed after the lapse of the predetermined time T2 or the charging is terminated, so that there is an effect that the charging is sufficiently performed and the charging shortage is eliminated.
[0024]
(Example 2)
Next, a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
[0025]
Generally, immediately after the start of charging, the battery voltage rises sharply, and as the charging proceeds, the battery voltage rise is suppressed. The battery voltage sampling period by the voltage detection means 7 of the battery voltage is short immediately after the start of charging, the battery voltage can be accurately measured even at a steep rise immediately after the start of charging, and the battery voltage sampling period is increased as charging progresses. Since there is not much voltage change, there is no problem even if the measurement is delayed. Since the battery voltage can be accurately measured at any time, the peak time can be accurately captured, and the charging current can be sufficiently supplied when the predetermined time T2 has elapsed from the peak time. By changing or terminating charging, there is an effect of sufficiently charging and eliminating insufficient charging.
[0026]
(Example 3)
Next, a third embodiment of the present invention will be described with reference to FIGS. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0027]
In order to measure the battery voltage, an amplifier 13, a second voltage detection unit 14, and a second peak value setting unit 15 are added, and the measurement is performed in a plurality of systems when the battery voltage is measured as it is and when it is amplified.
[0028]
In step 3, both the value of the first voltage detection means 7 (the current value of the 1-fold voltage) and the value of the amplified second voltage detection means 14 (the current value of the amplified voltage) are the respective peaks. The first peak value setting means 8 and the second peak value setting means 15 determine whether the value is equal to or greater than the value. If the value is smaller than the peak value, the second timer 12 starts counting, and the current value of the battery voltage is determined from the peak value. If the value is larger, the peak value is updated by the first peak value setting means 8 and the second peak value setting means 15 plus one count of the accuracy of the A / D converter, and the second timer 12 is updated. Reset. If the peak value is not updated in both the first and second peak value setting means 8 and 15, it is determined in step 4 that the second timer 12 has been fully charged if the predetermined time T2 has elapsed since the peak point. A trickle charge flag is set to change the magnitude of the charge current, or the charge is terminated.
[0029]
When amplification is performed, the change in the battery voltage also increases, so detection can be performed with high accuracy. However, if the absolute voltage of the battery voltage is greatly amplified due to variations in temperature, the amount of charge of the battery, etc., the voltage detection range will be exceeded. There is a case where the output of the detection means 14 is saturated and there is no change. FIG. 8 shows a case where the output of the second voltage detection means 14 is saturated and there is no change. In this case, the output of the first voltage detection means 7 with the battery voltage as it is changes, and the peak time can be detected. Point A is a case where the battery voltage remains as it is and the amplified voltage does not rise, that is, the point where the peak value is not updated in both the first and second peak value setting means 8 and 15 can be detected as the peak time point. Therefore, it is possible to accurately detect the peak time point that is the starting point of the end time in charging, and there is an effect that charging is sufficiently performed and insufficient charging is eliminated.
[0030]
( Reference Example 1 )
Next, a first reference example of the present invention will be described with reference to FIGS.
[0031]
In addition, the thing of the same structure as the said Example attaches | subjects the same code | symbol, and abbreviate | omits description.
[0032]
In FIG. 9, an amplifier 13, a second voltage detection means 14, and a second peak value setting means 15 are added to measure the battery voltage, and the measurement is performed in a plurality of systems when the battery voltage is measured as it is and when it is amplified. . In step 3, the value of the first voltage detection means 7 (1 times the current voltage value) and the peak value of the battery voltage as they are are determined by the first peak value setting means 8, and in step 4, a predetermined value ΔV1 is determined from the peak value. If it decreases above, the charging current is changed or the charging is terminated. In step 5, the value (amplified voltage current value) of the second voltage detection means 14 after the battery voltage amplification and the peak value are determined by the peak value setting means 15, and in step 6, a predetermined value ΔV2 or more is determined from the peak value. When it decreases, the charging current is changed or the charging is terminated.
[0033]
As shown in FIG. 10, when either of them decreases by ΔV1 and ΔV2 from their respective peak values, the magnitude of the charging current is changed or the charging is terminated. When amplification is performed, the change in the battery voltage also increases, so detection can be performed with high accuracy. However, if the absolute voltage of the battery voltage is greatly amplified due to variations in temperature, the amount of charge of the battery, etc., the voltage detection range will be exceeded. There is a case where the output of the detection means 14 is saturated and there is no change.
[0034]
FIG. 11 shows a case where the output of the second voltage detecting means 14 is saturated and there is no change. In this case, the output of the first voltage detection means 7 with the battery voltage as it is changes, and the peak time can be detected. Point B is the case where either the battery voltage as it is or the amplified voltage drops and the battery voltage drops by a predetermined value, that is, either the first or second peak value setting means 8 or 15 has its peak value. The points at which ΔV1 and ΔV2 are reduced from ΔV1 can be detected as the end of charging. Even if variations occur due to temperature, the amount of charge of the battery, etc., it is possible to accurately detect the end time of charging, and there is an effect of sufficiently charging and eliminating insufficient charging.
[0035]
【The invention's effect】
According to the invention set forth in claim 1 of the present invention, it is varied greatly battery voltage, carefully charging, the effect of eliminating the charging shortage.
[0036]
If according to claim 2 the invention described in the present invention, it captured the peak time accurately, the effect of eliminating carefully insufficient charging charging.
[0037]
According to the invention described in claim 3 of the present invention, it is possible to accurately detect the peak time point that is the starting point of the end time of charging, and it has the effect of sufficiently charging and eliminating insufficient charging of the battery.
[Brief description of the drawings]
FIG. 1 is a block diagram of a charger showing a first embodiment of the present invention. FIG. 2 is a main part flowchart of the charger. FIG. Direct update)
(B) Peak value update characteristic diagram of the charger (peak value is updated by 1 count)
FIG. 4 is a charging characteristic diagram of a charger showing a second embodiment of the present invention. FIG. 5 is a block diagram of a charger showing a third embodiment of the present invention. FIG. 7 is a charging characteristic diagram of the charger. FIG. 8 is a charging characteristic diagram when there is variation in the charger. FIG. 9 is a main part flowchart of the charger showing a first reference example of the invention. Charging characteristic diagram of the charger [Fig. 11] Charging characteristic diagram of the charger with variations [Fig. 12] Block diagram of the conventional charger [Fig. 13] Main part flowchart of the charger [Explanation of symbols]
6 Secondary battery 7 Voltage detection means 8 Peak value setting means 9 Signal control means 10 Charging terminal 13 Amplifier

Claims (3)

Comprising a voltage detecting means for detecting a voltage of the secondary battery, and a counting means for updating and storing the peak value is the maximum value of the past detection value detected by the voltage detecting means, said counting means Even if the current value of the voltage of the secondary battery measured by analog-digital conversion is larger than the stored peak value, the peak value is not directly updated to the larger value, and the peak value is analog-digital converted. A charger having a control means for changing the magnitude of the charging current or terminating the charging if the counting by the counting means is not updated for a predetermined time. . The charger according to claim 1, wherein the sampling period for detecting the voltage of the secondary battery immediately after the start of charging and after a predetermined time has elapsed since the start of charging is changed. Each of the voltage detection means for detecting the voltage of the secondary battery, the amplification means for amplifying the voltage of the secondary battery, the voltage detection means, and the maximum value among the past detection values detected by the amplification means. Counting means for updating and storing the peak value, the counting means, both the current value of the voltage of the secondary battery and the current value of the voltage of the secondary battery after amplification, measured by analog-digital conversion, Even if it is larger than each of the stored peak values, the peak value is not directly updated to the value when the peak value is larger, the peak value is counted by one count of the accuracy of analog-digital conversion, and is added and updated. A charger provided with a control means for changing the magnitude of the charging current or terminating the charging if both of the peak values of the voltage detecting means and the amplifying means are not updated for a predetermined time.

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