JPH03231175A - Apparatus for detecting capacity of battery - Google Patents

Abstract

PURPOSE:To accurately detect the capacity of a battery by calculating the capacity of the battery after the starting of an internal combustion engine on the basis of the integrated value of a charging/discharging current and the initial capacity of the battery. CONSTITUTION:An initial battery capacity detection part 11 calculates the initial capacity of a battery B at the starting time of an engine on the basis of the signals from a current detection part 1 and a voltage detection part 3. A charging/discharging current integrating part 13 integrates the charging/ discharging current of the battery B on the basis of the signals from the current detection part 1, the voltage detection part 3 and a temp. detection part 5. A battery capacity operation part 15 operates the capacity of the battery B at every predetermined time after the starting of the engine on the basis of the initial capacity of the battery B and the integrated value of the charging/ discharging current to output an alarm signal to an alarm part 9. The alarm part 9 is provided in the inner panel of a vehicle and informs the capacity insufficiency of the battery B to a driver on the basis of the signal from the battery capacity operation part 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a battery capacity detection device, and more particularly to a device for detecting battery capacity when an internal combustion engine is being driven.

[Prior Art] Conventionally, an on-vehicle battery covers the electrical load when starting the internal combustion engine, and also charges or discharges while the internal combustion engine is running depending on the balance between the generator output and the electrical load. Therefore, the capacity of the battery constantly changes. A technique for controlling the generated voltage of a generator in accordance with such changes in battery capacity is disclosed in Japanese Patent Laid-Open No. 122327/1983. This technology detects the charging current and discharging current of the battery and integrates them over time to calculate the amount of charging electricity and the amount of discharging electricity, respectively, and detects changes in battery capacity.

[Problems to be Solved by the Invention] However, when charging a battery, if the battery state is close to fully charged, gassing due to water electrolysis increases, and the ratio of gassing current to the charging current increases. Therefore, an error occurs between the amount of electricity actually charged to the battery and the integrated value obtained by integrating the charging current over time. That is, since the gassing current does not contribute in any way to charging the battery, the charging efficiency decreases, and when this integrated value is replaced with the amount of electricity charged in the battery, an error occurs. Therefore, if the battery capacity is estimated based on the amount of electricity charged and discharged by the battery over a long period of time, the capacity will be incorrectly determined to be large, even though the capacity is actually small. It is no longer possible to predict in advance when the battery will run out.

The battery capacity detection device of the present invention aims to solve the above problems and accurately detect the capacity of a battery.

The configuration of the present invention that achieves the above object will be described below.

[Means for Solving the Problems] As illustrated in FIG. 1, the battery capacity detection device of the present invention includes: current detection means M for detecting charging and discharging current of battery B; and detecting the voltage of battery B. initial capacity calculation means M3 for calculating the initial capacity of the battery B from the discharge current and voltage of the battery B at the time of starting the internal combustion engine; A battery capacity calculation means M4 calculates the battery capacity after starting the internal combustion engine based on the integrated value of the discharge current and the initial capacity of the battery B; The gist is that the integrated value correction means M5 corrects the integrated value based on the charging efficiency.

[Function] The battery capacity detection device of the present invention having the above configuration (like
When the internal combustion engine is started, the battery capacity calculating means M4 calculates the integrated value of the charging and discharging current detected by the current detecting means M1, and based on this integrated value and the initial battery capacity calculated by the initial capacity calculating means M3. to calculate the battery capacity after starting the internal combustion engine. When charging battery B, all of the detected charging current is
It does not contribute to the actual charging of battery B. That is,
It does not directly increase battery capacity. Therefore, if the battery capacity is simply calculated from the integrated value of the charging current, the calculated capacity will be excessive. Therefore, the integrated value correcting means M5 corrects the value related to the charging current out of the integrated value of the charging/discharging current based on the charging efficiency of the battery B taking into account the influence of gassing and the like. Therefore,
Battery capacity is accurately calculated. Note that the degree of gassing that affects the charging efficiency of battery B is determined by the degree of charging of battery B, temperature, voltage, etc.

Embodiments] In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the battery capacity detection device of the present invention will be described below.

FIG. 2 is a schematic configuration diagram of an in-vehicle battery capacity detection device as an example. Battery Bt& which is the object of capacity detection is a general lead-acid battery that supplies power to the stator S that starts the engine and various electrical loads, and is charged by the alternator A1 as a generator.

In-vehicle battery capacity detection device (composed of a current detection section 1, a voltage detection section 3, a temperature detection section 5, an electronic control device 7, and an alarm section 9). The voltage detection unit 3 detects the terminal voltage of battery B,
Temperature detection section 5 detects the temperature of battery B.

Electronic control unit 7 (well-known CPU, RAM, ROM, 1
/○ port, etc., and performs predetermined processing.If we pay attention to such processing, the initial battery capacity detection section 11. Charge/discharge current integration section 13. It consists of a battery capacity calculation section 15. The initial capacity of battery B at the time of engine startup is determined based on the signal from the battery initial capacity detection unit] 1 (current inspection unit) and the voltage detection unit 3. The charging/discharging current integration unit 13 Checking unit 3: integrates the charging/discharging current of battery B based on the signal from temperature detecting unit 5.Battery capacity calculation unit 15 starts the engine based on the initial capacity of battery B and the integrated value of the charging/discharging current. The capacity of battery B is calculated for each subsequent predetermined period of time, and an i-report signal is sent to the alarm section 9.

The alarm unit 9 is provided in an inner panel (not shown) of the vehicle, and is configured to notify the driver of insufficient capacity of the battery B based on a signal from a battery capacity calculation unit 5.

Next, the process of detecting a decrease in battery capacity executed by the electronic control unit 7 will be described with reference to the flowchart of FIG. 3. FIG. 3 shows a battery capacity reduction detection routine, which starts at the same time as an ignition switch (not shown) is turned on and the starter S is driven.

First, the current detection unit] takes in the signal from the voltage detection unit 3, and the discharge current of battery B is set to a predetermined value (for example, 150A).
The battery terminal voltage is measured when the voltage reaches the voltage (step 101). Next, the initial capacity of battery B, 5ocs, is calculated and stored based on the measured battery terminal voltage (step 02). This process is performed using a conversion table in which the battery terminal voltage during discharging and the battery capacity are stored as shown in FIG. The value of the initial capacity 5ocs of B is the current battery capacity (hereinafter referred to as
The current capacity is called 5OCN) (step] 03).

After these processes, a timer is started for determining the current capacity of battery B, 5OCN, at predetermined intervals (step 104). Next, a signal is taken in from the current detection section 1 and the charging/discharging current IC is measured (step 05). Next, it is determined whether the measured charge/discharge current IC is positive or negative (
Step 106). That is, it is determined whether the charging current (positive) flows to the side that charges battery B or the discharging current (negative) flows to the side that supplies the load. In this process, if it is determined that the current is a charging current, a process of correcting the value of the charging current is performed (step 07). This correction process will be explained below.

The charging current includes the gassing current used for gassing of battery B, that is, the gassing current used for water electrolysis, and this gassing current does not contribute equally to the charging (capacity change) of battery B, so the charging efficiency is decreases. As shown in FIGS. 5(A) to 5(T), this charging efficiency mainly changes depending on the capacity and terminal temperature of battery B. The process in step 107 calculates each charging efficiency α1. from the conversion table storing this relationship. α2. α3 is determined, the overall charging efficiency α is calculated as α=α1×α2×α3, and the value obtained by multiplying the charging/discharging current IC (charging current) measured in step 105 by this charging efficiency α is defined as the charging/discharging current IC. That's what I do. In addition, the charging efficiency α1 is the current capacity of battery B, 5OCN.
Charge efficiency α2. α3 (obtained by reading the signals from the surface pressure test section 3 and the temperature test section 5).

If it is determined in step 106 that it is a discharge current, this process is skipped and the process moves to step 108. This process is performed in step 105 or step 107.
The charging/discharging current C (positive in case of charging, negative in case of discharging) obtained in is integrated, and this integrated value is taken as the amount of change in battery capacity AH. Note that when this process is performed for the first time after starting this routine, the value of the battery capacity change amount Al-1 is reset to 0 as an initialization process, and the value of the charging/discharging current C is reset each time this process is performed. is added up.

Next, after confirming that the waiting time of ]Om seconds has elapsed (step 109), it is determined whether one minute has elapsed since the timer T started (step 1]o).

If 1 minute has not elapsed (ヱ) Return to step 105 and repeat the above-mentioned process. Therefore, the battery capacity change amount Al-1[1 in step 108 of the charging/discharging current IC every 10 msec after the timer T starts. This becomes the integrated value. Step 1] When the timer T determines that one minute has elapsed in 0, the current capacity 5OCN is corrected to the value obtained by adding the battery capacity change amount AH to the current capacity 5OCN obtained in step 103 ( Step] 11).

Subsequently, it is determined whether the corrected and determined current capacity 5OCN is less than or equal to a preset reference capacity socw (step]]2). If the reference capacity is less than 5 OCW, a dead battery alarm signal is turned on and a Y alarm signal is output to the alarm section 9 (step 113). Conversely, if the current capacity 5OCN is larger than the reference capacity socw, then it is determined whether the current capacity 5OCN is larger than the initial capacity 5ocs calculated in step 102 (step 115). Current capacity 5OCN is initial capacity 5o
If it is larger than cs, reset the current capacity 5OCN to the initial capacity, 1sOcs. Step 1] 5)
, turn off the low battery warning signal (step 1)
16). Conversely, if the current capacity 5OCN is less than the initial capacity 5ocs, the process of step 1]6 is directly performed.

When the process of step 116 or step 113 is completed, the timer T and the battery capacity change amount AHu are cleared to zero (step 117), and the process returns to step 104 to repeat the above-described process. Note that this routine ends when an ignition key (not shown) is turned off.

The battery capacity detection device of this embodiment described above calculates the current capacity 5OCN of the battery B by adding the integrated value of the charging/discharging current IC (battery capacity change amount A)-1) to the initial capacity 5ocs.

Moreover, the integrated value of the charging/discharging current IC is corrected by the charging efficiency α based on the battery capacity, i-terminal voltage, and battery temperature. From this, a decrease in the capacity of battery B can be reliably detected. In addition, even if the actual charging efficiency deviates from the value obtained from the conversion table due to deterioration of battery B, etc., if the calculated current capacity 5OCN is larger than the initial capacity 5ocs, then (Step 1) 5 Since the current capacity 5OCN is replaced with the initial capacity 5ocs, the problem that the current capacity 5OCN is judged to be larger than the actual capacity and the alarm is not issued does not occur.

That is, since the capacity of battery B is not judged to be excessive, the alarm is reliably issued. Therefore, the driver
Decrease in battery capacity can be recognized at an early stage, and the battery can be prevented from dying by reducing the electrical load, increasing engine speed, etc.

Next, a second embodiment of the present invention will be described based on a flowchart of FIG. 6 showing a battery capacity reduction detection routine. The configuration of the on-vehicle battery capacity detection device of this embodiment is the same as that of the first embodiment, and the same steps as those shown in FIG. 3 are given the same step numbers and only a brief explanation will be provided.

First, the current detection section when starting the engine].

The signal from the voltage detection unit 3 is taken in, and the initial capacity of battery B, 5ocs, is calculated and stored from the terminal voltage for a predetermined charging current value (step 101°] 02). continue,
It is determined whether the calculated initial capacity 5ocs is larger than the final value of the current capacity 5OCN determined last time (hereinafter referred to as final capacity 5OCNN) (Step 1] 8).

Note that the final capacity 5OCNN is always stored regardless of the end of this routine.

If the initial capacity 5ocs of battery B is larger than the final capacity 5OCNN, it is assumed that the measurement of the charging current terminal voltage in step 101 is incorrect, and the value of the initial capacity 5ocs is corrected to the value of the final capacity 5OCNN (step 11
9). If the initial capacity S○C8 is below the final capacity 5OCNNIJ, or after the processing in step 119 (step 120), the value of the current capacity S○CN and final capacity 5OCNN is reset to the value of the initial capacity 5OC8.

Next, in the same way as in the first embodiment, timer T is started, and the charge/discharge current IC is measured and corrected to integrate the charge/discharge current IC for 1 minute every 10 msec to obtain the battery capacity change amount AH (step 104-110). next,
Current capacity SOCN.

The value of the final capacity 5OCN is corrected to the value obtained by adding the battery capacity change amount AH to the current capacity 5OCN and final capacity 5OCN obtained in step 120 (Step) 2
1).

After the processing in step 121 (this is the same processing as in the first embodiment, if the current capacity 5OCN is less than the reference capacity 5OCW, the battery exhaustion alarm signal is turned on (steps 112 and 113). , if the current capacity 5OCN is larger than the reference capacity socw, turn off the battery exhaust warning signal (step 1] 6), and if the current capacity S○CN is larger than the initial capacity 5ocs, turn off the battery exhaustion alarm signal (step 1). The value is reset to the value of the initial capacity 5ocs (steps 114, 115).Steps 113, 1
When the processing of the alarm signal No. 16 is completed, the timer T and the battery capacity change amount AH are zeroed (step 11).
7) Return to step 104 and repeat the process described above.

Due to the installation of the in-vehicle battery capacity detection of the second embodiment described above (in addition to the effects of the first embodiment)
In step 8, it is possible to determine the erroneous measurement of the initial capacity of 5 ocs, and it is possible to detect a decrease in the capacity of battery B with high precision. In other words, the initial capacity S○C8 to be measured may have a measurement error due to the environmental history of battery B, etc., but the final capacity 5
If it is mistakenly determined that the current capacity is larger than OCNN, the value of the initial capacity 5OCS is replaced with the value of the final capacity 5OCNNO, thereby preventing the current capacity 5OCN from being judged to be larger than the actual capacity.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. It goes without saying that the present invention may be implemented in various ways without departing from the gist of the present invention. In addition, in this example, (friend charging efficiency α
Although the correction is performed before integrating the charging/discharging current 1c, a configuration may be adopted in which the charging current and the discharging current are integrated separately, and the integrated value of the charging current is corrected after the integration.

Effects of the Invention As detailed above, according to the battery capacity detection device of the present invention, the capacity when the battery is in use is determined by adding the integrated value of charging and discharging current to the initial capacity of the battery.
Furthermore, since the integrated value of charging and discharging current is corrected based on the charging efficiency of the battery, an excellent effect is achieved in that the capacity of the battery can be accurately detected. Therefore, unlike the conventional case, the battery capacity is not judged to be excessive, and the system becomes suitable for actual use.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram of an in-vehicle battery capacity detection device as an embodiment, FIG. 3 is a flowchart showing a battery capacity reduction detection routine, and FIG. The figure is a graph showing the relationship between battery terminal voltage and battery capacity during discharging, Figure 5 (a) is a graph showing the relationship between battery capacity and charging efficiency, and Figure 5
Figure (A) is a graph showing the relationship between battery terminal voltage and charging efficiency, Figure 5 (T) is a graph showing the relationship between battery temperature and charging efficiency, and Figure 6 is a graph showing the relationship between battery terminal voltage and charging efficiency. 3 is a flowchart showing a capacity reduction detection routine. ] 1... Current detection section 3... Voltage detection section 5...
Temperature detection section 7...Electronic control attachment 1...Battery initial capacity detection section 3...-Charge/discharge current integration section 5...Battery capacity calculation section

Claims (1)

[Scope of Claims] 1. Current detection means for detecting charging and discharging current of the battery; Voltage detection means for detecting the voltage of the battery; and determining the initial capacity of the battery from the discharge current and voltage of the battery at the time of starting the internal combustion engine. and a battery that calculates a battery capacity after starting the internal combustion engine based on an integrated value of charging and discharging current of the battery since starting the internal combustion engine, and an initial capacity of the battery. A battery capacity detection device comprising: capacity calculation means; and integrated value correction means for correcting a value related to charging current among the integrated values based on charging efficiency of the battery.