JPH03242575A - Apparatus for displaying residual power of battery - Google Patents

Abstract

PURPOSE:To easily recognize a drop in a storage battery capacity by calculating an initial index at present full charge from a first and previous discharge times according to a change ratio in discharge time and displaying this calculated index as the initial index at the time of full charge. CONSTITUTION:When storage battery 4 is empty and a charging switch SW is turned ON to start third charging, charge time tc, discharge time tD and an initial index Q0 are read out from a non-volatile memory 9. An index (%) Q2 indicating a calculated amount of consumption per unit hour dt is changed as dtXQ0/tD based on the discharge time tD. Thus by using Q1 (index (%) indicat ing a calculated amount to be accumulated on the storage battery 4 per unit hour dt) obtained based on the charge time tc calculated at the time of first charge in subsequent charging, if a capacity drop occurs due to deterioration of the storage battery the displayed index Q0 during charging does not exceed the deteriorated index so that the drop in capacity can be recognized.

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 for recognizing and displaying the remaining amount 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. 3 shows a display method for displaying the remaining amount of the battery or the usable time. FIG. 3(a) shows an example of percentage display, and FIG. 3(b) shows 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 4 and 5 below.
This will be explained using figures.

In FIG. 4, when the AC power supply 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 to 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 is started from the empty state of the storage battery 4 (step #1) (charging is performed in step #2), the control calculation unit 5 stores the battery for each pre-stored unit time dt! , 71!114 is sequentially added to the remaining amount Qo every dt time, and the addition result is displayed on the display section 7 in % or in units of time as shown in FIG. Loop from step #3 to step #7). And the remaining amount Q. When it 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 (released in step #2), the control calculation unit 5 calculates the capacity consumed per unit time dt stored in advance.
2 is sequentially subtracted from the remaining amount Qo every dt time, and the result of the subtraction is displayed on the display unit 7 in % or in units of time (loop from step #9 to step #12). In this way, the remaining fit Qo can be displayed with an inexpensive configuration.

Note that it is expressed as Q,=dtxlo, Q2=dtxID, and Io and I are predetermined charging current and discharging current.

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. 6. In this figure, the same numbers as those in FIG. 4 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 14, further converted into digital data by the A/D converter 15, and guided to the control calculation section 5. .

The control calculation unit 5 appropriately changes the ratio of addition and subtraction of the capacitances Q 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]

In both of the above conventional technologies, when a full charge is detected, the nominal capacity QMAX of the storage battery is used as the full charge state, but even if the storage battery deteriorates due to long-term use or other causes and capacity deterioration occurs, If the nominal capacity ffiQMAX is uniformly used as the capacity indicating full charge, the displayed remaining capacity will not match the actual capacity of the storage battery, making it difficult to properly display the remaining capacity.

In addition, although the timer method can be configured at low cost,
Charging current I of charging circuit 3. Errors occur due to variations in current ID and variations in current consumption ID to the load, resulting in low display accuracy, which is undesirable as it gives the user a sense of distrust. Furthermore, although the current integration method absorbs errors due to variations in charging current and discharging current, the current measurement resistor 13
Since the resistor 13 is inserted, the voltage drop across the resistor 13 deteriorates the starting performance of an electric motor such as a motor. In addition, with the recent demand for shorter charging times, it is necessary to increase the charging current.
The resistor 13 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 will be required in the amplifier 4 to ensure the desired accuracy, making it expensive. becomes.

The present invention has been made in view of the above-mentioned problems, and it is possible to accurately measure the full charge state without measuring the charging current during charging or the current consumption during discharging, and without being affected by variations in the charging current and current consumption. The present invention aims to provide a battery remaining capacity display device that calculates and displays the remaining capacity (initial index) or usable time.

[Means to solve the problem]

The present invention is 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 the consumption amount per unit time during discharging from an initial index when fully charged. , 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, a full charge detection means for detecting full charge, and a full charge. At times, the index for display indicating full charge is multiplied by the ratio of the discharge time measured the first time and the discharge time measured last time, and the index of the multiplication result is used as the initial index at the time of full charge. It also includes a control means used in place of the control means.

[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 initial index at full charge, and the index indicating the remaining capacity of the storage battery, which is the result of the subtraction, is 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. When full charge is detected, the index for displaying full charge is multiplied by the ratio of the first discharge time and the previous discharge time stored in the non-volatile memory, and this multiplication index is It is changed to the initial index at the time of full charge and used.

〔Example〕

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

Reference numeral 1 is an AC power source such as a commercial power source, and reference numerals 2 to 1 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. 11 is a temperature measurement circuit that outputs an analog voltage corresponding to the storage battery temperature detected by the temperature sensor 10;
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 when the battery voltage has dropped by dV (V) from the peak value and determines that the battery is fully charged.
V control method and other known methods can be used.

Further, the control calculation section 5 detects the connection state of the power switch SW and the operation switch SW, and detects the remaining f when fully charged.
A function to calculate it (initial index), when charging, adds an index indicating the capacity according to the charging time, - during normal charging and discharging, subtracts the index indicating the capacity according to the discharging time to indicate the remaining amount of the storage battery 4 A function to calculate the index (a function to determine the usable time), a display control function to display the index indicating the current remaining capacity on the display section 7, and a discharge time and other necessary times and indexes described below are stored in the non-volatile memory 9 as appropriate. It has a function to store data in 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 is timely written with a charging time, a discharging time, an initial index at full charge, and an index indicating the capacity according to the charging time at the time of charging based on commands from the control calculation unit 5, and the storage battery is discharged. The memory contents are retained even when the battery is empty and can be continued after a subsequent restart (charging). Note that the DC-DC converter 8 converts the electric power from the storage battery 4 into voltage levels required by the control calculation unit 5, display unit 7, A/D converter 12, etc. until the storage battery 4 is empty. It is provided by

Next, the remaining amount display operation will be explained with reference to the flowchart shown in FIG.

In this embodiment, the discharge time tD is stored in the non-volatile memory 9, and the first discharge time t is stored in the discharge time 1D. , and the previous discharge time t. The index Qo (initial index) indicating the remaining amount at full charge is changed using the ratio of M.

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

Qo, an index (%) for displaying the remaining capacity of the storage battery 4
. Note that the index indicating the remaining amount at full charge may be referred to as an initial index if necessary.

Q Index (%) tc for display indicating MAX full charge
: Actual discharge time required for full charge QIO Index (%) indicating the standard amount accumulated in the storage battery 4 per unit time dt Ql : Index indicating the calculated amount accumulated in the storage battery 4 per unit time dt ( %) tD: Actual discharge time from full charge. Note that the discharge time measured the Mth time is expressed as tDM.

Q20: Index (%) indicating the standard amount consumed per unit time dt Q2 - Index (%) indicating the calculated amount consumed per unit time dt To - Storage battery temperature TN at the start of charging - Unit time di Storage battery temperature T Ell[l
The value of (TN To) when fully charged.The unit of Qo etc. is %.
In addition, time (minutes), the number of screws that can be tightened, the number of holes that can be drilled, or ampere hours (Ah) may also be used. For example, when displaying the actual capacity as an index, such as ampere hours, the above symbols are Qzo = d t X Ic (Ah) Ql = d t
XQl, tAX /lc (Ah)Q20= d
t X In (A h) Q2 = d t xQMA
It may be defined in ampere hours per unit time as X/to (Ah). Other time units can also be obtained in the same way.

Now, when charging starts from the empty state of the storage battery 4, the values of internal counters (not shown) that measure the charging time tc and the discharging time 1D are both reset to O (step S1
), then the charging open tc1 discharge time tD and Qo are read from the nonvolatile memory 9 (step S2).

Initially, both the charging time tc and the discharging time to are not stored (NO in step S3), so the process moves to step S4, and as will be described later, an index Q20 indicating the standard amount as Q2
However, an index Q1o indicating a standard amount is used as Ql.

Then, in step S10, the tc flag is set.

By turning on the charging switch SW (step S □)
:4), when charging continues, the current discharging time tI) is canceled to O as described later, the tD flag is reset (step 512), and then the storage battery temperature T from the temperature measurement circuit 11 is .

is captured (step 513). Next, a built-in timer is used to determine whether 41 hours have elapsed. In other words, when 41 hours have passed (step S, YES)
), an index Q +, which indicates the standard amount in Qo.

is added, then a unit time dt is added to the charging time tc, and the storage battery temperature TN at this time is further measured (steps 315 to S-F). Then, the difference between the temperature at this time and the initial temperature (TN To) is compared to determine the magnitude of the predetermined value T END (step 518). Since the temperature difference is smaller than TEND until full charge (No in step S18), the Qo at that time is displayed on the display section 7 (step 519).

Then, when charging continues (step S
20), the process returns to step S14, and steps S L4 to S20 are repeated until the battery is fully charged. In other words, each time dt time elapses, QIO is added to Qo.
is added, the unit time dt is added to the charging time tc, and the Qo after the addition is displayed. Then, when the temperature difference becomes T END or more (YE in step S8).
S), charging is stopped by the charging control signal output from the control calculation unit 5 (step S2□). During the first charging, the discharge time 1 is not stored in the nonvolatile memory 9, so in this case, 100 (%) as the index QMAX for displaying full charge is written as the initial index Qo. (step 522). Then, it is determined whether the tc flag is set (step 523).
. If the tc flag is set (step S23
YES), the charging time t was measured assuming that the storage battery 4 was fully charged from empty. And the initial index Qo obtained in step S22 is written into the non-volatile memory 9 (step 524), after which the tD flag is set (step 525). Note that full charge may be detected by the above-mentioned 1 dV control method or other methods.

After this, when the operation switch SW is turned on and the storage battery 4 is connected to the load 6 (discharged at the step wall construction), the to flag is reset (step 526), and the dt dark time has elapsed using the built-in timer. It is determined whether That is, when the dt dark time has elapsed (YE in step S27)
S), Q20 is subtracted from Qo, and unit time dt is further added to discharge time tD (steps 828 and 529).
. Here, it is determined whether the tD flag is set (step S30). When discharging after full charge, the above tD flag is set (
Step S30: YES), this discharge time tD is written into the non-volatile memory 9 each time (Step 531)
.

Then, the Qo at this time is displayed on the display section 7 (step 532). If the discharge continues (YES in step S33), the process returns to step S27 until the operation switch SW is turned off (NO in step S33).
), the operations from step 327 to step S33 are repeated. In other words, each time dt time elapses, Qo
Subtraction of Q20 from, addition of unit time dt to discharge time tD, writing of the discharge time tD to nonvolatile memory 9, and Q
The display of o on the display section 7 is repeated. When the discharge continues and the storage battery 4 becomes empty, the discharge calculated just before
The time tD is the total discharge time of the non-volatile memory 9
will be finally written.

Note that only when fully charged (YES in step 318)
The D flag is set (step 525), and the set state of this to flag is confirmed during discharging (step S30).
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 512), 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
D is still retained. Also, the tc flag should be set at the start of charging after the storage battery 4 is empty in step S1.
O), this t when full charge is detected. The set state of the flag is confirmed (step 523), and the charging time t is determined. and the obtained initial index Qo are written, and the tc flag is reset by the time the full charge detection period ends (step 526), so only when the storage battery 4 is changed from empty to full charge. The charging time tc is written, and in other states, the previous charging time tc is still held. In addition, storage battery 4
The processing from step Sll onwards is performed until the space becomes empty.

After the storage battery 4 is empty, when the charging switch SW is turned on and the second charging is performed, the written charging time tc, discharging time to (=tD t) and initial index Qo are stored in the non-volatile memory. 9 (step S
2). At this time, since the charging time jcs and the discharging time rj1tD are stored (YES in step S3), step S
Move to 5. In step S5, Q2 is changed based on the read discharge time tD and initial index Qo.

That is, the total discharging time tD is the usable time according to the capacity and load current of the storage battery 4 used in this electric appliance, and therefore, in step S5, Q2 (dtXQo/lo ) will be changed to Furthermore, since tDl indicating the first discharge time is not stored (No in step S6), the previous Ql
Ql accumulated per dt time from o (=d t xQ
MAX /lc), and the discharge time tD at this time is obtained as the first discharge time 1D□ (step S7), and these Ql and tDl are written into the nonvolatile memory 9 (step Ss). .

Then, when charging continues (charging in step S□□)
, the discharge time to is canceled to 0, and tD
The flag is reset (step 512), and then the storage battery temperature To is taken in from the temperature measurement circuit 11 (step 513). Thereafter, steps S14 to S20 are repeated as described above until the battery is fully charged. When full charge is reached (Y in step 318)
ES), charging is stopped, and Qo, that is, the initial index at full charge, is Qo - QMAX X to 1
/ to 1 (in step S22, joM=
jot) (step S2□).

As a result, the initial index at full charge displayed on the display section 7 becomes Q MAX. Then, the charging time t obtained at this time
c and the initial index Qo are written into the nonvolatile memory 9.

After this, discharging is started (discharging in step 811),
When the storage battery 4 is empty, the second discharge time tD is t.
D2 is written to non-volatile memory 9 (step 531
).

After this, when the storage battery 4 becomes empty and the charging switch SW is turned on to perform the third charging, the written charging time tc, discharging time to (=tD2) and the initial index Q
o is read from the non-volatile memory 9 (step S2
). At this time, since the charging time tcs and the discharging time tD are stored (YES in step S3), the process moves to step S5. In step S5, as described above, the discharge time t
Based on D, Q2 is changed as dtXQo/lo. The first discharge time tD was memorized from the previous time, so (
(YES in step S6), the Ql calculated in step S7 last time is used as is from now on (step S9). In this way, the charging time t measured during the first charging. By using Q□ obtained based on for each subsequent charge,
When capacity deterioration occurs due to battery deterioration, the display index Qo during charging does not increase beyond the deterioration index, and the capacity deterioration can be recognized.

Then, when charging continues (charging in step S11), the discharging time t. is canceled to 0, and 1
．． The flag is reset (step 512), and then the storage battery temperature To is taken in from the temperature measurement circuit 11 (step 513). Thereafter, steps S L4 to S 20 are repeated as described above until the battery is fully charged. When the battery reaches full charge (YES in step 318)
), charging is stopped, and Qo, that is, the initial index at full charge, is determined as QO=QMAX X tD2/to 1 (step 522).

As a result, the initial index at full charge displayed on the display section 7 is an index obtained by multiplying the QMAX index by the ratio of the ↓ discharge time to the second discharge time. and,
The charging time tc and initial index Qo obtained at this time are written into the nonvolatile memory 9.

Subsequently, when discharge is started (discharge in step S Ll), the initial index Q. Q2 is subtracted from dt every unit time, the subtracted Qo is displayed, and at the same time, the discharge time tD (=tD2) until the storage battery 4 becomes empty is written into the nonvolatile memory 9 (step S31. 532)・After this, charging from step S1 is repeated, and (M
+1) When the 1st charging is started, the charging time is t. and M
tDM as the second discharge time tD is the nonvolatile memory 9
(YES in step S3),
Q2 is newly changed (step S5), and then Ql is used as is in step S9. Then, the same charging operation as described above is performed (step S2 to step S2).
0 ), when it reaches full charge (YES in step S□8)
, charging is stopped, and Qo, that is, the initial index at full charge, is determined as QO=QMAX x tDy/to 1 (step 522).

As a result, the initial index at the time of full charge displayed on the display section 7 becomes an index obtained by multiplying the index of Q MAX by the ratio of the discharge time of the first cycle to the discharge time of the M-th cycle. Therefore, when capacity deterioration occurs due to deterioration of the storage battery 4, the initial index Qo corresponding to the capacity after the capacity deterioration is displayed on the display section 7.

Then, when discharge starts (discharge in step S1□)
, Q2 is subtracted from the initial index Qo every unit time dt, the subtracted Qo is displayed, and at the same time, the discharge time tD (=joM+1) until the storage battery 4 becomes empty is written into the nonvolatile memory 9. (Steps S3□, S3□).

As a result, the display of Qo and the actual discharge state of the storage battery 4, for example, when the charging capacity of the storage battery decreases to 50%, Qo = 50 (%) is displayed as the initial index, and Qo = O
The time point when (%) is displayed and the time point when the storage battery M4 becomes empty coincides.

Note that in the above embodiment, accuracy is not achieved because no data is written in the non-volatile memory 9 at the time of first discharging. (1D.

By storing tc), the user can use the electric appliance with relatively accurate display from the first use.

Further, in the above embodiment, the initial index Qo calculated in step S22 is written into the nonvolatile memory 9 in step S24, and the QO is used for calculating Q2 (step S5) during the next charging. First discharge time tD
It is also possible to calculate Q2=d t

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.

Further, as the unit time dt, for example, a time suitable for the top plug, 1 minute, or other suitable time during design can be set.

〔Effect of the invention〕

As explained above, according to the present invention, the initial index at the time of the current full charge is calculated by so-called learning from the first and previous discharge times to be changed according to the change rate of the discharge time, Since the calculated index is displayed as the initial index at full charge, the user can easily recognize the capacity deterioration of the storage battery. Also, for this reason, the displayed index and the actual remaining capacity of the storage battery should be matched, for example, if the battery capacity has deteriorated to 50%, the initial index will be 50%.
% is displayed, and it is possible to match the display time of the index O indicating the remaining capacity with the point in time when the storage battery becomes empty, making it possible to display the index indicating the remaining capacity with high accuracy. Therefore, it is possible to provide highly reliable electric and electric equipment with low operating noise.

In addition, necessary time data such as discharge time and indices are written in non-volatile memory, so even if the storage battery becomes empty and the control means and other means become inoperable, the above memory contents will remain unchanged. maintained.

[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 explaining the operation of displaying the remaining battery amount, and Fig. 3 shows the conventional display method. FIG. 4 is a block configuration diagram explaining a conventional battery remaining amount display device, FIG. 5 is a flowchart explaining its operation, and FIG. 6 explains another conventional battery remaining amount display device. FIG. 2 is a block configuration diagram. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Rectifier, 3... Charging circuit, 4... Storage battery, 5... Control calculation section, 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 remaining capacity display device that displays an index indicating the remaining capacity of a storage battery obtained by sequentially subtracting an index indicating the consumption amount per unit time during discharging from an initial index when fully charged, A discharge time measuring means for measuring the discharge time required from charging until the storage battery becomes empty, a non-volatile memory in which the obtained discharge time is written, a full charge detection means for detecting full charge, and when fully charged, Multiply the index for displaying full charge by the ratio of the first measured discharge time to the previously measured discharge time, and replace the multiplication result index with the initial index at the time of full charge. A battery remaining amount display device comprising a control means for use.