JPH03242573A - Apparatus for displaying residual power of battery - Google Patents

Abstract

PURPOSE:To display an index indicating residual power of a storage battery with high precision by calculating an index indicating consumption rate per unit hour from a previous discharge until present discharge and displaying the index indicating residual amount obtained based on the above index. CONSTITUTION:When time dt has elapsed since an operation switch SW was turned ON and a storage battery 4 was connected to a load 6 (discharge), an index (%) Q20 indicating a standard consumption amount per unit hour dt is subtracted from an index (%) Q0 indicating residual amount of the storage battery 4, and further a unit hour dt is added to actual discharge time tD from the time when the storage battery was fully charged. The discharge time tD is written into a non-volatile memory 9 each time. The index Q0 at this time is displayed on a display unit 7. When discharge is to be continued, the above operation is repeated until the operation switch SW is turned OFF. When the storage battery 4 is empty after continuance of discharge, the discharge time tD which was calculated most recently is finally written into the non-volatile memory 9 as total discharge time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to electric and electric equipment using storage batteries, and particularly to a device that recognizes and displays the remaining power or usable time of a used battery.

[Conventional technology]

In electric equipment that uses rechargeable and dischargeable storage batteries, the remaining amount of battery or usable time, as well as the number of screws that can be tightened in the case of power tools, are used to inform the user of the equipment of the estimated usage time. There are known devices that display the number of holes that can be drilled.

FIG. 4 shows a display method for displaying the remaining amount or usable time of the battery. FIG. 4(a) is an example of percentage display, and FIG. 4(b) is an example of time display.

In addition, A□ to A5 and 81 to B5 in the figure are, for example, LEDs.
These display elements are used to notify the user by lighting up each element up to the corresponding percentage or time.

Conventionally, a timer method and a current integration method, which will be described later, are known as methods for generating such display data.

The timer method is a method that sequentially changes the display according to preset charging and discharging times, as shown in Figures 5 and 6 below.
This will be explained using figures.

In FIG. 5, when the AC power supply 1 is connected, that is, the charging switch SW is turned on, the AC power is full-wave rectified by the rectifier 2, and then converted into a predetermined charging current by the charging circuit 3.
It flows into a storage battery 4 such as a Ni-Cd battery and is charged. Meanwhile, the operation switch SW is turned on, and the load 6 and the storage battery 4 are
When connected, current is discharged from the storage battery 4 and supplies power to the load 6. The control calculation unit 5 detects the states of the charging switch SW and the operation switch SW to control charging and discharging. That is, the control calculation unit 5 has a function of detecting full charge and outputting a charge control signal to the charging circuit 3, a function of calculating the amount of charge during charging, an amount of discharge during discharging, and storing the remaining amount. It has a function of outputting and displaying the amount on the display section 7. Note that 8 is a DC-DC converter for supplying power to each part.

Next, the operation will be explained with reference to FIG.

Now, when charging starts from the empty state of the storage battery 4 (step #1) (charging in step #2), the control calculation unit 5 calculates the capacity Q is sequentially added to the remaining amount Qo every dt time, and the addition result is displayed on the display unit 7 in % or time units as shown in FIG. 4 (loop from step #3 to step #7). . Then, when the remaining amount Qo reaches the pre-stored nominal capacity Q MAX of the storage battery 6 (YES in step #5), charging control is performed and charging is stopped (step #8).

Next, when the operation switch SW is turned on, that is, discharge is started (discharging in step #2), the control calculation unit 5 calculates the capacity Q2 consumed per unit time dt stored in advance.
It sequentially subtracts from the remaining amount Qo every time, and displays the result of the subtraction in % or in units of time on the display unit 7 (
Step #9 to step #, loop of 2). In this way, the remaining amount Qo can be displayed with an inexpensive configuration.

Note that Ql=atx1. It is expressed as cSQ2 = dtXIo, where IC1ID are predetermined charging and discharging currents.

Further, the current integration method is a method of measuring charging current and discharging current, calculating and displaying the remaining amount as shown in Japanese Patent Laid-Open No. 61-209373, and will be explained below with reference to FIG. 7. In this figure, the same numbers as those in FIG. 5 indicate the same parts.

The charging current and discharging current detected from both ends of the current detection resistor 13 connected in series to the storage battery 4 are amplified by the amplifier 4, further converted into digital data by the A/D converter 15, and then introduced to the control calculation unit 5. It will be destroyed.

The control calculation unit 5 appropriately changes the ratio of addition and subtraction of the capacitances Ql and Q2 according to the magnitude of the input actual measured current value.

Then, the calculated remaining amount is displayed in % or in units of time. By using the measured current value in this way, accuracy can be improved.

[Problem to be solved by the invention]

Although the timer method can be constructed at low cost, the charging current of the charging circuit 3 is low. variation and current consumption to the load I
Display accuracy is low because errors occur due to variations in O.
This is not desirable because it gives the user a sense of distrust. Furthermore, although the current integration method absorbs errors due to variations in the charging current and discharging current, since the current measuring resistor 13 is inserted, the voltage drop across the resistor 13 deteriorates the starting performance of a motor such as a motor. In addition, in recent years, with the demand for shortening charging time, it is necessary to increase the charging current, but it is necessary to increase the charging current.
3 creates a new problem of heat generation.

Furthermore, if a low-resistance resistor 13 is used as a solution to the heat generation problem, the detection level will become smaller and the measurement error will increase, or noise countermeasures for the amplifier 14 will be required to ensure the desired accuracy, making it expensive. Become.

The present invention has been made in view of the above, and it is possible to accurately determine the remaining amount or usage without being affected by variations in the charging current and consumption current, without measuring the charging current during charging and the current consumption during discharging. The present invention aims to provide a battery remaining amount display device that calculates and displays the available time.

[Means to solve the problem]

The present invention provides a battery remaining capacity display device that displays an index indicating the remaining capacity of a storage battery obtained by sequentially subtracting an index indicating consumption per unit time during discharging from an index indicating full charge. , a discharge time measuring means for measuring the discharge time required from full charge until the storage battery becomes empty, a non-volatile memory in which the obtained discharge time is written, and a means for measuring the discharge time required from full charge until the storage battery becomes empty. Control that calculates an index indicating the consumption amount per unit time from the discharge time of the previous discharge stored in the non-volatile memory, and uses the calculated index in place of the index indicating the consumption amount per unit time of the previous discharge. and means.

Further, in a battery remaining capacity display device that displays an index indicating the remaining capacity of the storage battery obtained by sequentially subtracting an index indicating the consumption amount per unit time during discharging from an index indicating full charge, A non-volatile memory in which an index indicating the remaining capacity at the time when the storage battery becomes empty and an index indicating the amount consumed per unit time at the time of discharging are written, and the above-mentioned full charge at the time of discharging from the time when the storage battery becomes empty. index for displaying,
Calculate an index indicating the consumption amount per unit time according to the remaining amount ratio from the index indicating the previous remaining amount stored in the nonvolatile memory and the index indicating the previous consumption amount per unit time,
and control means for using the calculated index in place of the index indicating the amount consumed per unit time during the previous discharge.

[Effect]

According to the present invention, when discharging is started, an index indicating the amount consumed per unit time during discharging is sequentially subtracted from an index indicating full charge, and the remaining capacity of the storage battery, which is the result of the subtraction, is The indicated index is displayed. At this time, the discharge time required from full charge until the storage battery becomes empty is measured, and this discharge time is written into the nonvolatile memory. Then, when discharging from full charge until the Ti battery becomes empty is performed next time, the index indicating the amount of consumption per unit time from the discharge time of the previous discharge stored in the nonvolatile memory, for example, It is calculated by dividing the index used to display full charge by the previous discharge time and multiplying this by the above unit time, and the calculated index is changed to an index indicating the amount consumed per unit time during the previous discharge. and used.

Further, according to the invention as claimed in claim 2, when discharging is started, an index indicating the amount consumed per unit time during discharging is sequentially subtracted from an index indicating full charge, and the subtraction result is An index indicating the remaining capacity of a certain storage battery is displayed. At this time, an index indicating the remaining capacity at the time when the storage battery becomes empty and an index indicating the consumption amount per unit time at the time of discharging are written into the nonvolatile memory. The next time the battery is discharged from full charge until it becomes empty, the index for displaying full charge, the index indicating the previous remaining amount stored in the non-volatile memory, and the previous An index indicating the consumption amount per unit time according to the remaining amount ratio is calculated from the index indicating the consumption amount per unit time, and the calculated index is changed to an index indicating the consumption amount per unit time at the time of the previous discharge. It is used as

〔Example〕

FIG. 1 is a block diagram showing an example of a battery remaining amount display device according to the present invention.

1 is an AC power source such as a commercial power source, and 2 to 11 are circuit blocks constituting an electric device to which this remaining amount display device is applied.

2 is a rectifier consisting of a diode bridge or the like that performs full-wave rectification of the alternating current from the AC power supply 1; 3 is a charging circuit that converts the rectified current from the rectifier 2 into a charging current of a predetermined level; 4 is a charging circuit that performs charging from the charging circuit 3; It is a storage battery such as a Ni-Cd battery that is charged by current and supplies current consumption to a load 6, which will be described later. The charging switch SW is for connecting the electric device to the AC power supply 1, and the operation switch SW is for connecting the storage battery 4 to the load 6.

5 detects the connection state of the charging switch SW and operation switch SW, and at the time of charging, a temperature sensor 1 such as a thermistor is used.
This is a control calculation unit that detects full charge from the storage battery temperature obtained from 0 and outputs a charge control signal to the charging circuit 3 to stop charging. 1 (is a temperature measurement circuit that outputs an analog voltage corresponding to the storage battery temperature detected by the temperature sensor 10, 1
2 is an A/D converter that converts the analog voltage from the temperature measurement circuit 11 into a digital value and inputs it to the control calculation section 5. In addition, as a method of detecting full charge, the so-called -d method uses the charging characteristics of the storage battery to detect that the electric voltage has dropped by dV (V) from the peak value and determines that the charge is full.
V control method and other known methods can be used.

Further, the control calculation unit 5 detects the connection state of the power switch SW and the operation switch SW, and adds an index indicating the capacity according to the charging time when charging, while indicating the capacity according to the discharging time when discharging. A function to calculate an index indicating the remaining capacity of the storage battery 4 by subtracting the index (a function to obtain the usable time), a display control function to display an index indicating the current remaining capacity on the display unit 7, and a remaining capacity after charging is completed. The nonvolatile memory 9 has a function of storing an index (or usable time) and other required numerical values as necessary in the nonvolatile memory 9 described below. The display section 7 displays an index indicating the remaining amount (usable time) in a numerical display or a graph format, for example, in units of % or time, and is provided at a suitable location outside the electric device.

The non-volatile memory 9 stores an index indicating the remaining amount (usable time) and other numerical values as required (an index Q2 in a second embodiment described later) based on a command from the control calculation unit 5.
) is written in a timely manner, and the memory contents are retained even when the storage battery is discharged and empty, and the subsequent restart (charging)
This makes it possible to read the data from time to time.

Note that the DC-DC converter 8 stores electricity/l! ! The power from the storage battery 4 is transferred to the control calculation unit 5, until the storage battery 4 is empty.
It converts and supplies each voltage level required by the display section 7, A/D converter 12, etc.

Next, a first example of the remaining amount display operation will be described with reference to the flowchart of FIG. 2.

In this first embodiment, the discharge time to is stored in the non-volatile memory 9, and the discharge time t is stored in the non-volatile memory 9. The index Q2 indicating the amount consumed per unit time dt is changed from .

In addition, the definition of each symbol is as follows.

Qo VIiden/l! Index (%) for display indicating remaining capacity of lI4 QM^X Index (%) for display indicating full charge tCO charging current to predetermined current I. Standard time required for full charge when closed QIO Index (%) indicating the standard amount accumulated in the storage battery 4 per unit time dt tDo - Standard time available from full charge when the consumption current is set to the predetermined current ID to , Actual discharge time from full charge 020 Index (%) indicating the standard amount consumed per unit time dt Q2 - Index (%) indicating the calculated amount consumed per unit time dt To - Charging start Storage battery temperature TN/Storage battery temperature T per unit time dt (TN-TO) value when fully charged The number of possible holes, ampere hours (Ah), etc. may also be used. For example, when displaying the actual capacity as an index, such as ampere hours, the above symbols are t CO = Q MAX / I (Q,, = d t x Io (Ah) t DO = Q !IIAX / I.

Q2o=d t X ID (Ah)Q2=d t
It may be defined in units of ampere hours per unit time as X QMAX / t o (A h). Other time units can also be obtained in the same way.

Now, when charging starts from the empty state of the storage battery 4, first, the values of internal counters (not shown) that measure the Qos discharge time to are both reset to 0 (step wall construction).
Subsequently, the discharge time tD is read from the nonvolatile memory 9 (step S2).

Initially, the discharge time tD is 0 or is not stored (NO in step S3), so the process moves to step S4, and as described later, the index Q2o indicates the standard amount as Q2.
is used. When charging is continued by turning on the charging switch SW (charging in step S6), the current discharging time tD is canceled to O as described later, and
The to flag is reset (step S7), and then the storage temperature To is taken in from the temperature measurement circuit 11 (step Ss). Next, a built-in timer is used to determine whether the dt waiting time has elapsed. That is, when the dt waiting time has elapsed (YES in step S9), the index Q1o indicating the standard amount is added to Qo, and the storage battery temperature TN at this time is
is measured (step SIO, 5ll). Then, the difference between the temperature at this time and the initial temperature (TN To) is compared with a predetermined value T END to determine whether it is large or small (step 512). Since the temperature difference is smaller than T END until full charge (NO in step S12), the QO at that time is displayed on the display section 7 (step S14). When charging is continued, the process returns to step S9, and steps 89 to 4 are repeated until the battery is fully charged. That is, each time dt time elapses, Q lo is added to Qo, and the added Qo is displayed. Then, when the temperature difference becomes more than T END (
YES in step S12), and charging is stopped by the charging control signal output from the control calculation unit 5 (step S□
5), index QM for display indicating full charge as Qo
100 (%) as AX is written (step S□6
), and the to flag is further set (step S1□)
. Note that full charge may be detected by the above-mentioned -dV control method or other methods.

Thereafter, when the operation switch SW is turned on and the storage battery 4 is connected to the load 6 (discharged in step S6), a built-in timer is used to determine whether the dt waiting time has elapsed. That is, when the dt waiting time has elapsed (YE in step 818).
S), Q20 is subtracted from Qo, and the discharge time t.

unit time dt is added to (step 319, S2
0). Here, it is determined whether the tD flag is set (step 521). When discharging after full charge, the tD flag is set (YES in step S2), so this discharging time tD is written in the nonvolatile memory 9 each time (step 522).
. Then, the QO at this time is displayed on the display section 7 (step 523). If the discharge continues (YES in step S24), the process returns to step 818 and continues until the operation switch SW is turned off (NO in step S24).
O) The operations from step 818 to step S24 are repeated. In other words, each time dt time elapses, Qo
Subtraction of 020 from, addition of unit time dt to discharge time to, writing of the discharge time tD to nonvolatile memory 9, and Q
The display of o on the display section 7 is repeated. When charging continues and the storage battery 4 becomes empty, the discharge time to calculated immediately before is finally written into the nonvolatile memory 9 as the total discharge time.

Note that the 1D flag should be set only when fully charged (YES in step S12) (step 517), and the set state of this tD flag should be checked during discharging (step S2□
YES), write the discharge time tD, and write the current discharge time obtained up to that point, unless it is selected to continue discharging until the storage battery is empty. Since tD is canceled (step S7), the total discharge time is written only when the storage battery is emptied after being fully charged, and in other conditions, the total discharge time is written as when the storage battery 4 was previously discharged to empty. Total discharge time t.

is still retained. Also, until the storage battery 4 is empty,
Processing from step S6 onwards is performed.

Then, after the storage battery 4 becomes empty, when the charging switch SW is turned on and charging is performed again, the written total discharge time t. is read out from the non-volatile memory 9 (
step Sz). At this time, since the discharge time to is not 0 (YES in step s3), the process moves to step S5. In step S5, Q2 is changed based on the read discharge time 1D. That is, the total discharging time tD is the usable time depending on the capacity and load current of the storage battery 4 used in this electric appliance, and therefore, step S5
Then, Q2 consumed per dt time from Q20
(=d t XQMAX / tD(MatahaQ2=Q2
oxtDO/1D)). As a result, when the discharge occurs in step S6, the display of Qo and the actual storage/I
I! 4, for example, the time when Qo=O(%) is displayed coincides with the time when the storage battery 4 becomes empty.

Next, a second embodiment of the remaining amount display operation will be described with reference to the flowchart of FIG. 3.

In this second embodiment, the Qo is stored in a non-volatile memory 9; This is to change Q2 consumed per unit time dt.

Note that the same symbols as in the first embodiment have the same definitions, and other symbols are defined as follows.

Q'1. lAX: Index (%) indicating actual capacity, index Q MAX (%) and storage battery 4 for indicating full charge
An index Q that indicates the amount remaining when the is empty. (%) When charging starts from the empty state of the storage battery 4, the value of the internal counter that measures Qo becomes 0 and Q2 are both reset (step 531), and then the non-volatile memory Qo 1Q2 is read from 9 (step S3
゜).

Initially, Qa is not stored in the nonvolatile memory 9 (NO in step S33), so the process moves to step S34, Q20 is used as Q2, and this Q2 is written to the nonvolatile memory 9 (step 836). . When charging continues (charging in step S37), first the stored N/ll! from the temperature measuring circuit 11! 2 temperature To is captured (step 838). Thereafter, until charging is completed, Qlo is added to Qo every time the dt time elapses, and the Qo
is displayed (steps 839 to 544). Then, the temperature difference (TN-T.) is a predetermined value TEN[
When the value becomes 1 or more (YES in step S4□), charging is stopped by the charging control signal from the control calculation unit 5 (step 545), and the index QMAX is set to 100 ( %) is written (step 546).

After that, when the operation switch SW is turned on and the storage battery 4 is connected to the load 6 (discharged in step S37), the above-mentioned steps 39 to 524 (however, step S2
(excluding 0), each time dt elapses, Qo to Q
The subtraction of 20, the writing of the subtracted Qo into the non-volatile memory 9, and the display of Qo on the display section 7 are repeated. When charging continues and the storage battery 4 becomes empty, the Qo obtained immediately before is finally written into the nonvolatile memory 9 as an index indicating the final remaining capacity. Note that until the storage battery 4 becomes empty, the processes from step S37 onwards are performed.

After the storage battery 4 is empty, when the charging switch SW is turned on and charging is performed again, the written Qo and Q2 are read out from the nonvolatile memory 9 (step 5).
32). At this time, since Qo is stored in the nonvolatile memory 9 (YES in step 333), step S3
Move to 5. In step S35, the read Q
Q2 is changed using OQ2 and QMAX, that is, according to the remaining amount ratio as described below. That is, the index Q'MAX (=QMAX - Qo) indicating the actual capacity is calculated, and furthermore, Q2 written last time is calculated from this Q'MAX as the new Q2 (=Q2 XQMAX /Q'
MAX). This new Q2 is then updatedly written into the nonvolatile memory 9. As a result, when discharge occurs in step S37, Qo is displayed and the actual discharge state of the storage battery 4, for example, Q. - The time when 〇(%) is displayed and the time when the storage battery 4 becomes empty coincides. Related Qo=O(%)
While the display time and the time when the storage battery 4 becomes empty coincide, the same value as the immediately preceding Q2 is written into the nonvolatile memory 9 as Q2 (step 536).

On the other hand, the above Q.

- If the display time of 〇 (%) and the time when the storage battery 4 becomes empty no longer match, the previous Q2 is changed to a new Q2 according to the percentage of discrepancy, and this new Q2 is stored in the non-volatile memory 9. Written updated.

In this way, the display time of Qo=O(%) and the storage M4
It is possible to maintain consistency with the point in time when the data becomes empty.

For example, in an electric device such as a razor, where the load current changes depending on how the user uses it and the thickness of his beard, the display will be tailored to the user.

In addition, in this embodiment, the Q written to the nonvolatile memory 9
Since the value o is just before the power storage M4 becomes empty, there is a risk that incorrect data will be written, and therefore step S
It is determined whether the Qo stored immediately after 32 is within the allowable range, and if it is outside the allowable range, the first Q
20 may be selected to prevent erroneous display due to malfunction.

In addition, in each of the above-mentioned implementation columns, accuracy is not achieved because no data is written in the nonvolatile memory 9 at the time of first discharge.
If the first data (tD, Qo, Q2) is stored in the non-volatile memory 9 after being fully charged and completely discharged before shipment, the user will be able to obtain a relatively accurate display from the first use. This electric equipment can be used in this condition. In this case, Q20 does not need to be an index indicating an accurate standard amount, and may be any appropriate value (however, in step S5 of the first embodiment, as a conversion formula, Q2-
(Except when using Q2oxtDO/l).

Further, as described above, in the first and second embodiments, the data (tolQo, Q2
), so even if, for example, there is a deterioration in the capacity of the storage battery, a new Q2 will be updated at a rate corresponding to the current capacity.
can be updated and the accuracy maintained.

Furthermore, Qo may be calculated in units of ampere hours or the like, and only the display may be converted into % or units of time and displayed.

Also, there is no particular need to display Qo during charging;
In such a case, in the first embodiment, steps S9 and S in FIG.
1o, S13 in the second embodiment, step S in FIG.
39.54oXS43 becomes unnecessary.

Further, the unit time dt can be set to, for example, 1 second or 1 minute, which is suitable for the pond design.

〔Effect of the invention〕

As explained above, according to the present invention, an index indicating the consumption amount per unit time during the current discharge is calculated from the previous discharge state by so-called learning, and this calculated index is newly used. Since the index indicating the remaining amount obtained based on the new index indicating the consumption amount is displayed, the display state of the index indicating the remaining amount corresponds to the actual discharge state of the storage battery, for example, the index indicating the remaining amount. It is possible to match the time when 0 is displayed and the time when the storage battery becomes empty, and 5J
It is possible to display the index indicating fn with high accuracy. Therefore, highly reliable electric and electric equipment can be provided to users.

In addition, since the discharging time, the index indicating the remaining capacity, and the index indicating the consumption amount per unit time are written in the non-volatile memory, the control means and other means become inoperable when the storage battery becomes empty. Even if this happens, the above memory contents will be maintained as they are.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of an electric device to which the battery remaining amount display device according to the present invention is applied, FIG. 2 is a flowchart showing a first embodiment, and FIG. 3 is a flowchart showing a second embodiment. , FIG. 4 is a diagram showing a conventional display method, and FIG. 5 is a block diagram illustrating a conventional battery remaining amount display device.
FIG. 6 is a flowchart explaining its operation, and FIG. 7 is a block diagram explaining another conventional battery remaining amount display device. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Rectifier, 3... Charging circuit, 4... Storage battery, 5... Control calculation unit, 6... Load,
7...Display section, 8...DC-DC converter, 9.
...Nonvolatile memory, 10...Temperature sensor, 11...
Temperature measurement circuit, 12...A/D converter.

Claims (1)

[Claims] 1. A battery that displays an index indicating the remaining capacity of the storage battery obtained by sequentially subtracting an index indicating the consumption amount per unit time during discharging from an index indicating full charge. The remaining capacity display device includes a discharge time measuring means for measuring the discharge time required for the storage battery to become empty from full charge, a non-volatile memory in which the obtained discharge time is written, and a discharge time for the storage battery to become empty from full charge. An index indicating the amount consumed per unit time is calculated from the discharge time during the previous discharge stored in the non-volatile memory during the discharge up to, and the calculated index is used as an index indicating the amount consumed per unit time during the previous discharge. A battery remaining amount display device comprising a control means used in place of the battery. 2. In a battery remaining capacity display device that displays an index indicating the remaining capacity of the storage battery obtained by sequentially subtracting an index indicating consumption per unit time during discharging from an index indicating full charge, A non-volatile memory in which an index indicating the remaining capacity at the time when the storage battery becomes empty and an index indicating the amount consumed per unit time at the time of discharging are written, and the above-mentioned full charge at the time of discharging from the time when the storage battery becomes empty. , an index indicating the previous remaining amount stored in the non-volatile memory, and an index indicating the previous consumption amount per unit time, indicating the consumption amount per unit time according to the remaining amount ratio. A battery remaining amount display device comprising: a control means for calculating an index and using the calculated index instead of an index indicating the consumption amount per unit time at the time of previous discharge.