KR930011222B1 - Lower voltage battery detection method and the system - Google Patents

Abstract

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Description

Low battery detection method and system

1 is a graph showing a cell voltage characteristic curve when currents emitted from a battery are 200 mA, 400 mA, and 600 mA, respectively.

2 is a graph showing a curve of battery voltage characteristics when the charging time is 1 hour, 2 hours, 4 hours and 8 hours, respectively.

3 is a block diagram of a low battery detection system of the present invention.

4 is a detailed block diagram of the power controller shown in FIG.

5 is a table for storing the correspondence between the voltage change amount and the reference voltage information value for low battery detection.

6A and 6B are flowcharts showing processing operations of low battery detection.

* Explanation of symbols for main parts of the drawings

1: Power Controller 1a: Power Control CPU

2: battery 4: host CPU

3: DC / DC converter 11: current detector

13: voltage detector 19: internal bus

The present invention relates to a battery detection system and method for use in a personal computer using a battery as a power source.

A personal computer having a function of using the battery as a power source and monitoring the remaining capacity of the battery by a power supply controller has been developed.

When detecting a state (low battery state) in which it is difficult to operate a personal computer normally due to a small amount of battery remaining capacity, conventionally, the current and battery voltage emitted from the battery are monitored, and the current and voltage satisfy certain conditions. When I did not let it was recognized as a low battery.

This method is specifically described using the battery characteristic diagram shown in FIG. The battery characteristics of FIG. 1 show how the battery voltage changes over time. The vertical axis represents battery voltage and the horizontal axis represents time. The three graphs shown in the battery characteristics of FIG. 1 indicate the change of each battery voltage when the currents emitted from the battery are 200 mA, 400 mA, and 600 mA. As shown in FIG. 1, the larger the current emitted from the battery, the faster the drop of the battery voltage is.

Point A on the vertical axis indicates that the personal computer cannot operate normally when the battery voltage falls above this level, and point C on the horizontal axis indicates the time when the battery voltage becomes A when the current emitted from the battery is 600 mA. Point B on the horizontal axis is a reference point for judging whether or not the battery is a low battery. Even when judging as a low battery state when the maximum amount of current emitted from the battery is 600 mA, the operation of the personal computer can be guaranteed at least between (CB). have.

In the conventional method, the current discharged from the battery and the battery voltage were monitored, and it was determined that the battery was a low battery when the voltage at the point B (B'-I, B'-II, B'-III) was reached. In a personal computer using a battery, the longer the driving time as the battery is, the better. For this purpose, accurate detection of the low battery and the use of the battery up to the allowable limit become one element of extending the driving time by the battery. In the conventional system, there is a problem in that the detection of the low battery cannot be made accurately because the influence of the error due to the state of the battery to be used is large. This will be described with reference to FIG. The battery characteristic shown in FIG. 2 shows the voltage change of a battery having a different charging time. Point A on the vertical axis indicates the voltage at which the normal operation of the personal computer stops when the battery voltage drops further, and point B 'on the vertical axis indicates the battery voltage determined by the low battery. The time from the determination of the low battery to the stop of the personal computer operation (Cn-Bn: n = 1, 2, 3, 4) is longer for the battery having a longer charging time. Therefore, in the conventional method, even if it is judged as a low battery, the remaining capacity may still remain sufficiently, so there is a drawback that the battery cannot be used efficiently.

SUMMARY OF THE INVENTION An object of the present invention is to provide a battery detection system and method which can prolong the driving time by a battery by accurately detecting a battery condition.

According to a first aspect of the invention, a low battery detection method comprises the steps of: a) reading a current emitted from a battery, b) obtaining a reference voltage for battery detection from the current read in step a), and c Reading the voltage of the battery; d) obtaining a voltage change amount from a battery voltage read last time and a battery voltage read this time; and e) calculating a reference voltage for detecting the low battery in response to the voltage change amount. Comparing the corrected low battery detection reference voltage with the voltage read in step c), and determining that the battery is low when the voltage read in step c) is lower than the reference voltage for detecting the battery. Steps.

According to a second aspect of the present invention, a low battery detection system includes: means for measuring a discharge current of a battery; Means for obtaining a reference voltage for low battery detection from the measured current; Means for measuring a battery voltage; Means for obtaining a voltage change amount from the measured voltage and the voltage measured last time; Means for correcting a reference voltage for low battery detection in accordance with the amount of voltage change; Means for comparing the corrected low battery detection reference voltage with a measured battery voltage; As a result of the comparison, means for determining as a low battery when the measured battery voltage is lower than the corrected reference value for detecting the low battery.

According to the present invention, the combination of the three factors of the battery voltage, the current discharged from the battery, and the amount of change in the battery voltage realizes accurate detection of the battery according to a program for determining the battery. By detecting the low battery state according to each of these determination factors, the low battery state can be detected accurately, and the battery driving time can be extended.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating one embodiment of the present invention. The power supply controller 1 is connected to the host CPU 4 via the system bus 5, and detects the low battery of the battery 2 according to the voltage, current, and voltage change of the battery 2, and performs the low battery. The state is transmitted to the host CPU 4. The power supply controller 1 incorporates a power supply control CPU 1a. The battery 2 is connected to the power supply controller 1 and the DC / DC converter 3 and supplies DC power to the DC / DC converter 3. The DC / DC converter 3 generates a DC power supply having a constant voltage necessary for operating the personal computer main body from the DC supplied from the battery 2. The host CPU 4 has a function of notifying the user of the information of the low battery sent from the power controller 1.

4 is a detailed block diagram of the power controller shown in FIG. In FIG. 4, the current detector 11 is connected in series with the battery 2, and the voltmeter 14 is connected in parallel. Each output (analog value) of the ammeter 11 and the voltmeter 13 is supplied to the first and second A / D converters 15 and 17, respectively, and the analog values are converted into digital values, respectively. Each output of the first and second A / D converters 15 and 17 is supplied to the CPU 21 via the system bus 19. The system bus 19 is further connected with a RAM 23, a ROM 25, a parallel I / O interface 27, and a programmable interrupt timer (PIT) 28. The CPU 21, the RAM 23, the ROM 25, the first and second A / D converters 15 and 17, the parallel I / O interface 17 and the PIT 28 are, for example, single chip microcomputers. It consists of a computer.

The RAM 23 is a software counter 23a for measuring the time for one second each time an interrupt enters the PIT 28, and a time memory 23b for storing the time taken for the battery voltage to drop 59mv as described later. Equipped with. The default value of the software counter 23a is 0, and the default value of the time memory 23b is 32. The ROM 25 stores a table 25a for detecting the low battery reference voltage and a table 25b for correcting the reference voltage of the low battery. The low battery detection table 25a displays the correspondence between each input current value and the low battery reference voltage value. The CPU 21 converts and takes the analog value from the current detector 11 into a digital value by the A / D converter 17, and obtains a low battery reference voltage corresponding to the detected current value with reference to the conversion table.

The low battery correction table 25b stores a value calculated in advance in consideration of the difference in charging time and the resolution of the first and second A / D converters 15 and 17. That is, in this embodiment, the battery voltage is read at intervals of one second to obtain a difference from the battery voltage read last time, and it is determined whether or not it has fallen by 59mv or more. The time which fell more than 59mv was measured, and the correction value of a low battery reference voltage is obtained with reference to a low battery correction table using that time as a parameter. In the low battery correction table shown in FIG. 5, the time taken for the 59mv falling is a parameter because the resolution of the A / D converter used is 59mv per digital value. Since the correction value of the reference voltage can calculate the slope of the battery voltage characteristic curve from the time taken to drop 59 mv, it is possible to estimate how long the charging time will take according to the battery voltage characteristic diagram shown in FIG. .

Therefore, the correction value of the reference voltage is calculated in advance from the battery voltage characteristic curve corresponding to the charging time and stored in the ROM 25.

In addition, the CPU 21 reads the voltage from the voltage detector 13 at a predetermined sampling time (1 second in this embodiment), converts it into a digital value in the first A / D converter 15, and stores it in the RAM 23. . The CPU 21 subtracts the battery voltage read this time from the battery voltage read last time and calculates the voltage change amount.

In addition, the CPU 21 programs the PIT 28 to interrupt at one second intervals, and executes the flowchart shown in FIG. 6 in response to the interrupt signal from the PIT 28. At this time, the CPU 21 installs a software counter in the RAM 23 and adds one second to the software counter every time an interrupt signal is applied.

5 shows a voltage conversion correction table for low battery detection.

As shown in FIG. 5, this correction table stores a correction value of the low battery reference voltage in correspondence with the time required for the battery voltage to drop to 59mv. For example, + 177mv is added to the low battery reference voltage in 8 seconds or less, + 118mv is added in 8-12 seconds, and + 0v is added in 32 seconds or more.

Next, the operation of one embodiment of the present invention will be described with reference to the flowcharts shown in FIGS. 6A and 6B.

The CPU 21 increments the contents of the software counter 23a installed in the RAM 23 in step S1. The initial value of the software counter 23a is '0'. Next, in step S3, the current value from the current detector 11, that is, the discharge current value of the battery 2, is read through the A / D converter 17. In step S5, the CPU 21 refers to the low battery detection reference voltage conversion table 25a to obtain a low battery detection reference voltage from the current value.

Next, in step S7, the voltage of the battery 2 is read from the voltage detector 13 via the A / D converter 15. Next, in step S9, the battery voltage read out this time is subtracted from the battery voltage read out previously, and the difference voltage is calculated | required. In step S11, it is determined whether or not the difference voltage is 59mv or more. If it is not 59mv or more, the process proceeds to step S15. In this case, the low battery reference voltage correction table 25b is referred to in accordance with the time data when it was set in the time memory 25b when it was lowered by more than 59mv last time. On the other hand, if it is determined in step S11 that it is 59mv or more, the content of the software counter 23a installed in the RAM 23 is stored in the time memory 23b in step S13.

Next, in step S15, the contents of the time memory 23b, i.e., the time taken to descend by 59mv or more, are read, and with reference to the reference voltage correction table 25b for the battery installed in the ROM 25 according to the value, The correction value corresponding to the time is obtained. In step S19, the corrected low battery reference voltage is compared with the measured battery voltage. If the battery voltage value is smaller than the low battery reference voltage value, the CPU 21 notifies the host CPU 4 of the low battery in step S21. . As a result, the host CPU 4 receives this notification and, in response to this, turns on the low battery indicator LED lamp or notifies the operator with a buzzer.

As described above, in the present invention, since the battery reference voltage is corrected to average the difference between Cn and Bn (n = 1, 2, 3, 4) shown in FIG. The time until the personal computer stops normal operation becomes constant regardless of the charging time.

While the present invention has been described above with reference to one embodiment of the present invention, those skilled in the art may make various changes and modifications to the present invention without departing from the scope of the invention as defined by the following claims. It is obvious. Therefore, the present invention is not limited to the above-described embodiments, but is defined by the following claims, but the reference numerals written in each component of the claims are merely for reference for easy understanding of the present invention and each component. It should be understood that the present invention is not intended to be limited to the embodiments shown in the drawings.

Claims (12)

A low battery detection method, comprising: (a) reading a current emitted from a battery (S3); b) obtaining a reference voltage for detecting a low battery from the current read in step (a) (S5); (c) reading the voltage of the battery (S7); (d) obtaining a voltage change amount from the battery voltage read last time and the battery voltage read this time (S9); (e) correcting the reference voltage for detecting the low battery in response to the voltage change amount (S17); (f) comparing the corrected low battery detection reference voltage with the voltage read in step (c) to determine the low battery when the voltage read in step (c) is lower than the low battery detection reference voltage ( S19), characterized in that a low battery detection method. The method of claim 1, wherein the step (b) comprises obtaining a reference voltage for battery detection according to a battery voltage characteristic curve (FIG. 1) corresponding to a different current value. 2. The low battery detection according to claim 1, wherein said step (e) comprises correcting a reference voltage for low battery detection according to a battery voltage characteristic curve (FIG. 2) obtained corresponding to a different charging time. Way. 4. The method of claim 3, wherein the correcting of the battery includes: after determining that the battery is a low battery, correcting the time until the device driven by the battery stops the normal operation so as to be uniform for different charging times (Bn-Cn). A low battery detection method comprising the. First table memory means (25a) for storing a correspondence between the current emitted from the battery and the reference voltage for low battery detection; Second table memory means 25b for storing a correspondence between the amount of change in battery voltage and a reference voltage correction value for low battery detection; Means (11) for measuring a current emitted from the battery; Means (21) for obtaining a reference voltage for low battery detection with reference to the first table memory means according to the measured current; Means (13) for measuring battery voltage; Means (21, S9) for obtaining a voltage change amount from the measured battery voltage and the last measured battery voltage; Means (21, S17) for correcting a reference voltage for low battery detection with reference to said second table memory means in accordance with the obtained voltage change amount; And a means (21, S19) for judging a low battery of said battery using a corrected low battery detection reference voltage. 6. The method according to claim 5, wherein the means for obtaining the reference battery for detecting the low battery 21 includes means for obtaining the reference voltage for detecting the battery according to a battery voltage characteristic curve (FIG. 1) corresponding to different current values. Low battery detection system. 6. The method according to claim 5, wherein the means for correcting the low battery detection reference voltage (21, S17) corrects the low battery detection reference voltage according to a battery voltage characteristic curve (FIG. 2) obtained corresponding to different charging times. A battery detection system comprising means. 8. The method according to claim 7, wherein the correcting means (21, S19) determines that the battery is a low battery, and then uniforms the time (Bn-Cn) until the device driven by the battery stops normal operation for different charging times. And means for compensating for termination. Means (11) for measuring the discharge current of the battery; Means (21, S5) for obtaining a reference voltage for low battery detection from the measured current; Means (13) for measuring battery voltage; Means (21, S9) for obtaining a voltage change amount from the measured voltage and the last measured voltage; Means (21, S17) for correcting a reference voltage for detecting a low battery according to the voltage change amount; Means (21, S19) for comparing the corrected low battery detection reference voltage with the measured battery voltage; And a means (21, S21) for determining that the battery is a low battery when the measured battery voltage is lower than the corrected reference value for detecting the low battery. 10. The method according to claim 9, wherein the means for obtaining the reference voltage for detecting the low battery (21, S5) comprises means for obtaining the reference voltage for detecting the low battery according to the battery voltage characteristic curve (FIG. 1) corresponding to different current values. Low battery detection system, characterized in that. 10. The method according to claim 9, wherein the means for correcting the low battery detection reference voltages (21, S17) corrects the low battery detection reference voltage according to a battery voltage characteristic curve (FIG. 2) obtained corresponding to different charging times. A battery detection system comprising means. 10. The apparatus according to claim 9, wherein the means for correcting means for correcting the time Bn-Cn to be uniform for different charging times after determining that the correcting means is a low battery and until the device driven by the battery stops normal operation. Low battery detection system comprising a.

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