JP3188553B2 - Charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rechargeable nickel alloy.
The present invention relates to a charging device for a cadmium battery or the like.

[0002]

2. Description of the Related Art When a battery is charged, the battery voltage increases until the battery is fully charged, and the battery voltage decreases when charging is continued after the full charge. That is, the battery voltage becomes maximum in the fully charged state. Various techniques have been proposed to stop charging at the timing when the battery voltage becomes maximum using this phenomenon.

For example, Japanese Patent Application Laid-Open No. 63-234844 discloses a technique in which a battery voltage is detected every predetermined period and charging is stopped when it is found that the voltage has continuously dropped a predetermined number of times or more. Have been. According to this, the charging is stopped immediately after the full charge. FIG. 1B shows the details of this procedure. In step B1, the previous battery voltage (V
0) and the current battery voltage (VN). When the latter is larger than the former, the counter is cleared to zero (B3),
On the other hand, when the latter is equal to or smaller than the former, the counter is set to 1
Step forward (B2). Then, when the count value of the counter reaches a predetermined value, step B4 becomes YES and charging is stopped (B5). Until the predetermined number of times is reached, the processing after B1 is repeated every predetermined period. Step B6 replaces the previous battery voltage (V0) with the current battery voltage (VN). According to this technique, as shown in FIG. 1 (A), the counter is incremented after the battery voltage reaches a maximum, and charging is stopped when the battery voltage starts to decrease continuously. Note that ΔV in the figure indicates VN−VO, and + V
Is when the current detection value is larger, = is equal,-
Indicates a case where the current detection value is smaller.

[0004]

In an actual work site,
The large motor may be turned on and off near the charging device, and the power supply voltage is likely to fluctuate. Therefore, FIG.
The battery voltage as indicated by the black point in (C) may be detected. If the power supply voltage fluctuates irregularly or periodically as described above, the previous detection value and the current detection value fluctuate. Even though the battery voltage is in a falling period as a whole, sometimes the current detection value is smaller than the previous detection value. The counter value may be larger than the detected value, and when such a phenomenon occurs, the counter is cleared to zero each time. As a result, the increment of the counter is delayed, and the charging is not stopped unless the charging is continued for a considerable period after the full charge. If the charging is continued even after the full charge, the battery life is shortened. Therefore, in the present invention, it is possible to more stably detect a timing close to the full charge timing.

[0005]

For this purpose, the present invention provides a device for charging a battery by supplying a charging current to the battery, wherein the device detects a battery voltage every predetermined period during charging.
A device that extracts and stores the maximum voltage among the detected battery voltages, compares the detected battery voltage with the maximum voltage, and advances one step when the former is equal to the latter.
A counter that increments by n (here, n is an integer of 2 or more) when the count value is smaller than a predetermined value, and a device that stops the supply of the charging current when the count value of the counter becomes a predetermined value or more. A charging device characterized by the following was created.

[0006]

[Operation] As shown in FIG. 1 (1), the present detection value (VN)
Is not the previous detected value (V0) but is compared with the maximum voltage (VPEAK) up to that point. Even if the power supply voltage fluctuates a little, the V voltage is stably maintained while the battery voltage is on a downward trend as a whole.
PEAK ≧ VN, and the counter continues to advance. That is, even if VN> V0 happens to occur, the counter is not cleared to zero, and VPEAK ≧ VN
As long as. For this reason, after the battery voltage reaches the maximum, the counter rapidly advances and reaches a predetermined value. In this way, it is possible to prevent the charging from continuing for a considerable period even after the battery is fully charged .
Note that when VN = VPEAK, one step is advanced, and VN <VP
If a counter that advances by 2 or more is used at the time of EAK, the counter will rapidly advance after full charge and charging will be stopped at a timing closer to full charge .

[0007]

FIG. 3 shows a system configuration of an example of a charging device embodying the present invention. The current supplied from the commercial power supply 2 is rectified by the rectifying / smoothing circuit 4 and then smoothed, and is turned on / off by the switching element 6. The transformer 8 steps down the commercial voltage and supplies a charging current to the secondary side.
This current is rectified by the rectifying / smoothing circuit 9, smoothed, and supplied to the battery 10. The battery 10 includes a plurality of 1.2-volt cells, a 7.2-volt battery containing six cells, a 9.6-volt battery containing eight cells, and a 12-cell battery having 12 batteries. Any of the 0.0 volt batteries is used.

The secondary side circuit is provided with a charging current detecting circuit 12 and a battery voltage detecting circuit 14. Further, a temperature-sensitive switch (specifically, a thermostat) 16 that is turned on / off as the temperature of the battery rises is also provided. These are input to the microcomputer 18. An auxiliary power supply 20 is attached to the transformer 8 and the microcomputer 1
8 is supplied with a power supply voltage. Microcomputer 18
Executes the processing described below in accordance with a predetermined program, and sends the processing result to the primary side control circuit 26 via the photocoupler 24. The primary side control circuit 26 controls ON / OFF of the switching element 6 based on the processing result of the microcomputer 18. A drive voltage is supplied to the primary side control circuit 26 from the auxiliary power supply 22 attached to the transformer 8.

The microcomputer 18 receives the signal of the charging current detection circuit 12 and adjusts the duty ratio of the switching element 6 so that the charging current has a substantially constant value. 4 and 5, the switching element 6 is fixed to OFF when the battery 10 is fully charged. 4 and 5 compare the current detection value VN with the maximum voltage VPEAK so far, and stop charging if VN ≦ VPEAK continues. However, as will be described later, the comparison is not performed until the condition that the battery voltage starts to fluctuate greatly is satisfied, and the comparison between VN and VPEAK is started only when the battery voltage greatly fluctuates. This process prevents erroneous determination.

The processing shown in FIG.
Shows the processing procedure executed by the
0, a predetermined time (T1) after the start of charging
Is executed when elapses.

The predetermined time (T1) is a predetermined time, and is a time at which the initial voltage fluctuation shown by the lines A5 and A6 in FIG. 2 almost ends. When the overdischarged battery is charged, the battery voltage first rises sharply (line A).
5) After that, it falls once (line A6), and then gradually rises like a normal battery (line A2). After a lapse of T1 time from the start of charging, the battery voltage takes a value well corresponding to the rated voltage of the battery, regardless of the degree of discharging at the start of charging. On the other hand, the battery voltage at the start of charging may not be related to the rated voltage. For example, the battery voltage V00 (A) having a rated voltage of 12 volts may be lower than the battery voltage V0 (B) having a rated voltage of 7.2 volts. You get. When the time T1 elapses after the start of charging, the above-mentioned problem is solved, and the initial voltage fluctuation that occurs when the overdischarged battery is charged has also subsided. I have.

The process of FIG. 4 is programmed to be executed when a predetermined time (T1) has elapsed after the start of charging based on such knowledge. First, in step S2, the battery voltage at that time is detected and V1 is detected. To be stored.

Next, at step S4, the detected battery voltage V1 is compared with a predetermined voltage. The charging device of this embodiment is rated at 7.2 volts, 9.6 volts, and 12.0 volts.
It is planned to charge a battery having three rated voltages of volts, and V9.6L, 9.6 volts, and 12.12 as predetermined voltages for dividing 7.2 volts and 9.6 volts.
V9.6U is used as a predetermined voltage for classifying 0 volt. V9.6L uses 9.6 volt battery
V9.6U is a value slightly higher than the maximum voltage, which is slightly lower than the lowest voltage among the battery cells generated when the battery is charged for one hour. If V1 ≦ V9.6L, rating 7.
A 2 volt battery is charged and V9.6L <V1 <
If V9.6U, a battery with a rated 9.6 volt is charged, and if V1 ≧ V9.6U, a battery with a rated 12.0 volt is charged.

In FIG. 4, step S6 is executed when the battery is rated 7.2 volts, step S8 is executed when the battery is 9.6 volts, and step S10 is executed when the battery is 12.0 volts. Is done. Step S6, S
8, S10 are a predetermined potential difference ΔVS, values ΔVS (7.2), ΔVS (9.
6) and ΔVS (12.0) are stored.

After the above processing is completed, the processing is temporarily terminated (step S12). Next, when a predetermined period has elapsed, FIG.
Is executed by interruption. The process of FIG. 5 is thereafter executed every predetermined period (S14). Note that a timer in the microcomputer 18 is used to execute the timer every predetermined period. First, in step S16, the battery voltage is read and set to VN (step S16). Next, the current battery voltage VN is compared with the current maximum voltage VPEAK. If the current battery voltage exceeds the current maximum voltage, that is, if step S18 is NO, the current voltage VN is compared with the maximum voltage VPEAK. (Step S20). If the current maximum voltage VPEAK is higher, step S20 is skipped. While the voltage is increasing, that is, VN> V
During the PEAK, the counter value is set to zero (step S
22). While the voltage is increasing, the processing after step S24 is not executed, and the process is temporarily terminated (step S36). Step S16 is a process executed by the device that detects the battery voltage every predetermined period, and steps S18 and S20 are processes executed by the device that extracts and stores the maximum voltage. That is, the battery voltage detecting device is constructed by the battery voltage detecting circuit 14, the microcomputer 18, and the program for executing the processing of FIG. 5 (particularly, step S16). 5 (particularly steps S18 and S20).

When the present battery voltage VN is equal to or smaller than the maximum voltage VPEAK up to that time, step S24 is executed. Here, a value obtained by adding a predetermined potential difference (ΔVS) to a battery voltage (V1) when a predetermined time (T1) has elapsed after the start of charging is compared with a current battery voltage (VN). Here, V1 is stored in step S2 of FIG. Also, ΔV
S represents steps S6, S8, S1 according to the rated voltage of the battery.
It is set to one of 0.

The processing in step S24 is performed in step S26.
This is for determining whether or not to skip the subsequent processing. The processing is skipped during no and executed when the determination is yes. When the battery is charged, the battery voltage increases as shown by the line A in FIG. That is, the voltage rise rate increases before the battery is fully charged (see line A3). Step S24 is for judging whether or not the voltage suddenly changes as indicated by the line A3. The processing after step S26 is not executed at the time indicated by the line A2, that is, while the voltage fluctuation is small.
This is because if the comparison of VN ≦ VPEAK is performed during this time, if the voltage is detected with a coarse resolution, VN = VPEAK. On the other hand, after line A3,
Even if detection is performed at a coarse resolution, VN and VPEAK are not always equal, and accurate comparison can be performed even at a coarse resolution.

The processing after step S26 is based on the battery voltage VN
Is to detect the timing at which the voltage starts to fall after reaching the maximum voltage. Therefore, if the current battery voltage VN is smaller than the maximum voltage VPEAK, the value of the counter is set to 2
In step S28, if they are equal, the counter is advanced by one (step S30).
VN> VPEAK does not occur). As a result, VN ≦
The number of times the relationship of VPEAK is continuously detected is counted by the counter. At this time, counting is performed once when VN = VPEAK, and twice when VN <VPEAK. When it is surely falling, it counts with weight.

The number counted as described above is compared with a predetermined number in step S32. VN ≦
If VPEAK continues, charging is stopped in step S34. That is, the switching element 6 is kept in the off state. The microcomputer 18, the switching element 6, and a program for executing step S <b> 34 in FIG. 5 constitute a charging stop device. If the value of the counter has not reached the predetermined number of times, step S32 is NO, and the process of FIG. 5 is repeated. And when VN> VPEAK,
Step S18 becomes no, and the counter is cleared to zero (step S22). That is, by this processing, V
Even if N ≦ VPEAK, charging is not stopped unless charging is continued, and a process of stopping charging when the charging is continued is executed.

When it is known that VN <VPEAK and the drop has occurred as described above, step S32 is quickly set to YES by counting with weighting. In this embodiment, the counter is incremented by two in step S28, but may be incremented by 3, 4, 5,....

In the case of this embodiment, steps S26 to S26 are executed.
S32 constitutes means for detecting the timing at which the battery voltage starts to fall after it has reached the maximum, and this processing is executed only when the result of step S24 is YES. (VN) is a predetermined potential difference (Δ
VS), the timing detecting means operates after the voltage becomes equal to the sum of the voltage and the voltage. Step S34 is a means for stopping the charging current, which is executed when the timing at which the charging current starts to fall after being maximized in steps S26 to S32 is detected.

The advantages of this embodiment will be described with reference to FIG. In the case of this embodiment, when the voltage rise rate becomes large immediately before the full charge state, the inversion from the rise to the fall is detected. That is, the inversion is detected when the voltage fluctuation within the predetermined period is large. For this reason, the voltage detection accuracy may be relatively rough. For example, the voltage fluctuation of the solid line may be originally detected as a broken line (the broken line has a coarse resolution). If the detection resolution is low, it will not be erroneously detected that a reversal phenomenon from rising to falling has occurred due to a minute change in the battery voltage. If the resolution is coarse, detection delay may be a concern. In the present embodiment, not only VN <VPEAK but also VN = VPEAK is included in the count. For this reason, since the counter advances after the timing of X in FIG. 6, it is possible to detect a timing that is very close to the timing of inversion from rising to falling. VPEAK = VN
However, when the counter is incremented, when detection is performed with a coarse resolution, actually even if VPEAK <VN, VPEAK = VN
And sometimes. In this embodiment, VPEAK and VN are compared only when the voltage changes greatly.
Even a coarse resolution does not cause any inconvenience.

As described above, according to this embodiment, the timing detection performance does not deteriorate even with a coarse resolution. In addition, since the coarse resolution is sufficient, it is possible to use inexpensive electronic components and the like. In order to detect the timing at which the battery voltage changes from rising to falling, the deviation of the battery voltage within a predetermined period is taken, and after it has changed from positive to negative, it is determined whether or not the negative fluctuation has continued for a predetermined number of times. You may look. However, in this method, erroneous detection may be caused by a slight fluctuation of the power supply voltage. On the other hand, in this embodiment, erroneous detection hardly occurs because the voltage is compared with the maximum voltage instead of the voltage fluctuation within the predetermined period.

In the case of this embodiment, step S24 in FIG.
May be determined, the extraction processing of the maximum voltage in steps S18 to S20 may be executed. Further, the processing of FIG. 7 may be added. That is, a means for operating after the battery voltage becomes a voltage obtained by adding the predetermined potential difference (ΔVS) to the battery voltage (V1) at the lapse of the predetermined time (T1), and detecting the timing at which the battery voltage changes from rising to falling. It may consist of a plurality of means.

A step S72 detects a timing at which the voltage fluctuation ΔV within a predetermined period becomes a value obtained by subtracting a fixed value from the maximum fluctuation ΔVMAX. If a constant value is set as an appropriate value for each rated voltage of the battery, step S72 can be set to be YES just before the timing when the battery voltage changes from rising to falling. Similarly, in step S74, the inversion timing from the rise of the battery voltage to the fall can be detected. After the battery is fully charged, it has a characteristic that the temperature rises suddenly. If the thermostat is set at this temperature, step S7
4, the full charge timing can be detected.

Step S76 is to check the timing when the battery voltage VN becomes lower than the maximum voltage VPEAK by a predetermined value (ΔVC). If the absolute value of ΔVC is set to a small value, the battery is fully charged. You can see that it has become. Steps S26 to S32 and S72, S74, S
The present invention can also be embodied by executing one or more of 76.

[0027]

According to the present invention, since the detection of the full charge state is performed by comparison with the maximum voltage, the counter keeps stepping up against the fluctuation of the power supply voltage and the like, and the timing close to the full charge timing Stops charging.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing the principle and operation of the present invention in comparison with a conventional example.

FIG. 2 is a diagram showing a battery voltage during charging.

FIG. 3 is a system diagram of an embodiment.

FIG. 4 is a processing procedure diagram of an embodiment.

FIG. 5 is another processing procedure diagram of the embodiment.

FIG. 6 is a diagram for explaining the operation of the embodiment.

FIG. 7 is a diagram showing a modification of the embodiment.

[Explanation of symbols]

Battery voltage detection device for each predetermined period 14: Voltage detection circuit 18: Microcomputer Processing procedure of step S16 in FIG. 5 Maximum voltage extraction / storage device 18: Microcomputer Processing procedure of steps S18 and S20 in FIG. 5 Counter 18: Microcomputer Processing procedure of steps S28 and S30 in FIG. 5 Charge stopping device 6: switching element 18: microcomputer Processing procedure of steps S32 and S34 in FIG.

Claims (1)

(57) [Claims] 1. A device for charging a battery by supplying a charging current to the battery, a device for detecting a battery voltage at predetermined time intervals during charging, and extracting and storing a maximum voltage among the detected battery voltages. and to keep device, the detected battery voltage compared to the maximum voltage, after the former
Step forward when equal to the former, n when the former is smaller than the latter
(Where n is an integer of 2 or more) A charging device comprising: a stepping counter; and a device that stops supplying a charging current when the count value of the counter becomes equal to or more than a predetermined value.