JP3304507B2 - Battery remaining capacity meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery state-of-charge meter particularly suitable for detecting the state of charge of a battery used as a driving source for a vehicle such as an electric vehicle.

[0002]

2. Description of the Related Art Heretofore, several different methods have been used as means for detecting the remaining capacity of a battery used as a driving source for an electric vehicle. One is to measure the battery's open circuit voltage in relation to the battery's capacity with a simple linear or quadratic function. A residual capacity meter based on this type of interrelation is described in Japanese Patent Application Laid-Open No. 57-149144.

Another method measures the output current of the battery while using the battery as an energy source. This type of detection is commonly known as Peukert
Take advantage of formula I ⁿ t = C. Where I is the discharge current, n is a value greater than 1 based on the battery type, t is the discharge time,
C is a constant. The Peukert equation describes the well-known phenomenon that the capacity of a battery decreases as the current increases. In JP-A-59-56177, NASA Technical Note D-5773, 1970, etc., the remaining capacity of a method of measuring battery current, converting the signal using the Peukert equation, and integrating the converted signal with respect to time is described. Several reports have been reported. The accumulated used capacity is continuously deducted from the current value of the battery capacity.

[0004]

However, the two methods described above for measuring the remaining capacity of a battery have significant drawbacks. Remaining capacity meters based on open circuit voltage measurements show accurate values only when no current is flowing and the battery approaches the equilibrium voltage. When the electric vehicle travels in a typical urban driving pattern, there are very few opportunities to measure the open circuit voltage. This is because the vehicle is constantly moving and current is flowing from the battery. In the worst case, where the vehicle never stops at a stop before it runs out of battery capacity, measurements will not be taken until the battery capacity is exhausted after the vehicle starts to start.

[0005] Remaining capacity meters based on converting the input current signal to a value that can be integrated over time using the Peukert equation are known to cause significant errors in normal operating conditions. For a battery that has been fully charged by a normal method, the integration can be restarted from the start point by turning on the reset switch. However, if the battery is partially charged, e.g., to charge 60% of the capacity by a quick-charging device, the capacity meter must also be capable of current integration in the opposite direction of discharge, since resetting is not possible. Unfortunately, accurate reverse current integration is difficult. This is because the charging efficiency of the battery changes unpredictably with temperature, depth of discharge, and charging conditions. If partial charge / discharge of the battery is continuously performed and reset cannot be continuously performed, the degree of error will be severe.

[0006] Further, all the well-known types of remaining capacity meters cannot correct for the aging of the battery. The main reason is that the aging of the battery changes considerably depending on the situation in which the battery is charged or discharged. Another problem with the known remaining capacity meter is related to a display format in which output information is displayed. Typically, capacity is displayed as a fraction or as a percentage of battery capacity. This is to require the user to know the correlation between the displayed value and the corresponding usage that the battery powered device emits for each displayed output unit. The discharge to zero capacity of the battery occurs earlier than expected by the user before the correlation is confirmed by the user, which is a very inconvenient point for the user.

It is an object of the present invention to incorporate the convenient features of the above two types of residual capacity meters into one residual capacity meter,
The purpose is to eliminate the disadvantages while utilizing the advantages of both. Further easiest way to correct for aging of the battery remaining capacity meter including.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The battery remaining capacity meter according to the first aspect of the present invention includes a voltage measuring unit that measures a terminal voltage of the battery, a current measuring unit that measures a terminal current of the battery, a temperature measuring unit that measures a temperature of the battery, Terminal voltage, terminal current,
Calculating means for calculating from the remaining capacity temperature, storage means for storing the calculation result, it has a display means for displaying the calculated results, before
The calculating means may determine that the current is zero for a certain time.
An open circuit voltage is estimated based on the terminal voltage,
According to a polynomial relating the open circuit voltage and the remaining capacity,
First calculating means for calculating the remaining capacity of the battery;
When a zero or more current flows in the discharge direction of the battery,
Subtracting the integrated value of the terminal current from the current remaining capacity
And second calculating means for calculating the remaining capacity by
Of the remaining battery capacity of battery-powered devices
And the polynomial used by the first calculating means is
The battery with the minimum current that can drive the battery drive device
Is a polynomial expressed assuming that constant current discharge occurs.
The calculating means is configured to store the residual volume by the second calculating means.
With the amount calculation process interposed, the remaining by the first calculation means
If the capacity calculation process is performed twice, the first total
Difference value of the remaining capacity of the new and old two times calculated by the calculation means
And the remaining capacity during the processing period of the second calculating means
Of the polynomial, so that both are equal.
The coefficients used in the equation are determined . Claim
The invention according to claim 2 is the invention according to claim 1 above.
The second calculating means calculates the integrated value of the terminal current by the product
Compensation based on the terminal current value and temperature during the minute period.
Is to be corrected . The invention according to claim 3 is the above-mentioned invention.
In the invention according to claim 1, the first calculating means
Stores time and voltage data in a memory device,
The combination of the accumulated time and voltage data is related by a logarithmic function.
Using the logarithmic function for time values of 10 ³ seconds or more
The open circuit voltage value is calculated . Claim 4
The invention according to claim 2 is the invention according to claim 2, wherein
The second calculation means measures the average current and temperature for a certain time
And use the Peukert equation with an index corresponding to the measured temperature.
Corresponding to the lowest available current corrected by the current value.
Time and calculate the temperature at which the battery capacity was measured.
Using the temperature compensation function,
Calculate the time corresponding to the lowest available current and
At the time of correction by the current and temperature to the minimum usable current value in degrees
By taking a while, the consumable capacity for a certain period of time can be accumulated.
Is to be calculated.

[0009]

According to the present invention, two different calculation principles are used.
The combination of the two basic remaining capacity calculation methods provides a remaining capacity meter with the best features of both methods. The first basic remaining capacity calculation method is a method using an open circuit voltage. In this method, the open circuit voltage is estimated and calculated in a certain time when the current value is zero. Using this open circuit voltage value, the current battery capacity is calculated from a simple function of the open circuit voltage value and the battery capacity. In an electric vehicle, such a measured current value is zero only when the vehicle is started or when the vehicle is stopped by congestion or stopped at a traffic light. Opportunities for these zero current measurements to occur are few, and in some cases very few. Therefore, the total number of measured data is not sufficient as the basic data for a continuously responding remaining capacity meter, but this kind of rare measured data may not be sufficient for actual battery capacity under certain circumstances as described below. Can be used to provide an accurately measured reference point for another basic remaining capacity meter which has the disadvantage of deviating from the value of

The second basic remaining capacity detection method used in the present application is a remaining capacity calculation method based on a coulometer. The coulometric remaining capacity meter integrates the current flowing from the battery, and periodically deducts the calculated integrated consumption capacity from the battery capacity value calculated or measured in advance. As a well-known characteristic of a battery, there is a phenomenon that when the used current increases, the consumed capacity further increases than the increased current. In the present invention, in order to correct this, the integrated current is corrected by using the relationship of the Peukert equation, and integration and subtraction are performed. Temperature correction is also necessary and implemented. The coulometric remaining capacity meter using the subtraction of the accumulated consumption capacity can accurately obtain the actual battery capacity as long as the remaining capacity value at the start of the subtraction process is accurate. The exact remaining capacity value at the start of the deduction, the reference point, is provided by the above-described open-circuit voltage-based remaining capacity meter that functions when the current is zero.

The present invention uses two types of remaining capacity meters to not only provide an accurate value of the battery capacity on a continuous basis, but also adjust for changes in the capacity of the battery over time. Peukert regardless of battery aging
The coulometer portion of the remaining capacity meter, which calculates the current and temperature corrected integrated capacity values using the formula, will continue to be accurate.

Since the integrated capacity is thus accurate, this value can be used to correct a simple function representing the relationship between open circuit voltage and remaining capacity in the first scheme. The value of the battery capacity is initially, for example, when starting an electric vehicle,
It is measured and calculated by the capacity calculation method based on the open circuit voltage. If the vehicle then travels a certain distance, during which time the current goes to zero for a short time, no second open circuit voltage measurement is made. During this time, the remaining capacity is continuously updated using the coulometer part of the remaining capacity meter. The vehicle stops, for example, at a signal, at which time a new open circuit voltage measurement is obtained. The difference in battery capacity due to the difference between the two open circuit voltage measurements and the integrated capacity by the coulometer between the two open circuit voltage measurement times should be equal if the battery does not change over time. When the battery capacity changes due to aging, a function indicating the relationship between the open circuit voltage and the capacity in the first method is adjusted using the integrated capacity value between two reference points by the coulometer. As a result of the adjustments in these two complementing methods, the necessity of the next adjustment will be completely numerically consistent until it is detected and executed.

[0013]

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the embodiments, in order to facilitate understanding of the present invention, a description will be given of the discharge characteristics of a battery, which is a known fact. FIG. 2 shows the relationship between terminal voltage and discharge time when a fully charged sealed lead-acid battery having a nominal capacity of 30 Ah is discharged at a constant current until the end of discharge. As shown, the voltage gradually decreases over most of the discharge period, and decreases abruptly when the available capacity is exhausted. The battery capacity in this discharged state can be obtained by multiplying the discharge current and the elapsed time until the voltage suddenly drops. Discharge time as the discharge current increases to decreases as Peukert formula (I ⁿ t = C). Where I
Is the discharge current, n is a value greater than 1 depending on the battery type, and C is a constant. Discharge duration (min)
FIG. 3 shows the relationship between the discharge current and the discharge current (A) in a log-log table. From the linear regression equation of the data in this figure, the values of n and c are each 1.313.
And 3.386 × 10 ³ . Since the time to the end of the discharge decreases as the discharge current increases, the capacity naturally also decreases. If a fully charged battery is discharged at several different constant currents, the capacity will also change according to the above function. FIG. 4 shows the relationship between the discharge current value of the 30 Ah nominal capacity battery and the dischargeable capacity. Further, the capacity of the battery at constant current discharge gradually changes as the number of cycles increases. It is well known that capacity generally decreases with increasing number of cycles. 28Ah
One example of such a variation in a nominal capacity sealed lead acid battery is shown in FIG. Finally, FIG. 6 shows the relationship between the open circuit voltage and the remaining capacity of the 30 Ah nominal capacity battery at an early stage of the cycle life. The relationship between the remaining capacity and the open circuit voltage is represented by the following equation for this battery.

Remaining capacity = 20.685 × (open circuit voltage-11.7) If the 30 Ah nominal capacity battery changes over time as shown in FIG. 5, the coefficient of 20.685 will first increase to a maximum. Thereafter, it decreases monotonically with the battery cycle.

(Embodiment 1) FIG. 1 is a circuit diagram of an embodiment for realizing a battery state of charge meter according to the present invention. 1 terminal voltage of the battery detection circuit (voltage detection means), 2 battery discharge current (terminal conductive
Current detection circuit (current detection means) . In particular,
The method of detecting the terminal voltage by the resistance division is simple. The method of detecting the discharge current includes a method using a shunt resistor connected in series with the battery load, a method using a current sensor using a Hall element, and the like. The current detector of the device is configured such that only the discharge current is measured as a positive value, and no reverse current, ie, the charging current is measured at that time. 3 is a battery temperature detection circuit
(Temperature detecting means) . The detected terminal voltage and discharge current are subjected to low-pass filters 4 and 5 to remove AC components. This is due to the fact that the discharge characteristics of the battery are governed by the extremely slow-changing phenomenon of diffusion of the electrolyte, which depends on the average discharge current value. The signal from which the AC component has been removed and the signal for detecting the temperature are converted into digital signals by the A / D converter 9 through the sample and hold circuits 6, 7, and 8, respectively. The following various program steps are stored in the ROM (read only memory) 11, and the remaining capacity of the battery is calculated.

A function relating the open circuit voltage to the battery capacity defined by the lowest drive current for a battery powered device.

A function of the Peukert equation that determines the consumption capacity integrated over time.

Various constants necessary for the calculation are also stored in the ROM . Microcomputers 10 (calculating means) terminal voltage value converted into the digital signal, the discharge current value, reads the temperature of the battery, calculates the remaining capacity value to execute a program command from the ROM 11, the calculated remaining capacity value The corresponding binary data is output to the latch circuit 12 (storage means) . The binary data is, for example, data decoded for driving the pointing device. The latch circuit 12 holds the previous data until new data is sent from the microcomputer 10. Pointing device 1
3 (display means) indicates the remaining capacity value by the data held in the latch circuit 12.

The above circuit configuration is merely an example. For example, instead of the low-pass filters 4 and 5, a digital low-pass filter can be used for data read into the microcomputer 10, and the sample-and-hold circuit 6 and 7 and 8 can also use one sample and hold circuit in a time division manner. If a D / A converter is used, an analog voltmeter can be used as the indicating device. Further, it is not the intention of the inventor to limit the output display means to the above embodiment.

FIG. 7 shows a typical flowchart of the programmed function steps executed by the microcomputer part of the battery state of charge meter according to the present invention . As can be seen from FIG. 7, the remaining capacity is calculated continuously from the start of driving the battery-powered device until the device stops. The program has two branches. The left branch (open circuit voltage branch) operates when the current value is zero for the entire period of the fixed time t _SET , and calculates a new value of the battery capacity (in other words, a new capacity) (first).
Calculation means) . The main branch on the right (coulometer branch) is activated when current is flowing in the discharge direction at zero or more, and calculates the consumption capacity (hereinafter referred to as △ capacity) obtained by integrating the current with respect to time. New value of battery capacity by subtracting △ capacity from current value of battery capacity (in other words, new capacity)
Is calculated (second calculation means) .

A schematic flow chart of the left branch in FIG. 7 is shown in the upper part of FIG. A more detailed flowchart of the program steps in this open circuit voltage branch is shown in FIG.
Shown below. In the first step after entering this branch, the memory space in the microcomputer is initialized in order to store a voltage-time data pair (V _N , t _N ) continuously measured for a certain time t _SET . Perform In the next step, one data pair is measured and stored in the memory space. next,
A condition determination is made as to whether the battery current value is zero and the elapsed time has not yet reached t _SET . If the current remains zero for a period of time t _SET , the voltage and time data pairs are fully stored in memory space and provided for subsequent calculations. If the current value becomes a non-zero value before reaching t _SET , No is selected in the next condition judging unit (elapsed time t ≧ t _SET ?), And the calculation is performed with the open circuit voltage branch without updating the battery capacity value. Get out of. If you continue to be the entire period current is zero until reaching the t _SET, YES under the following conditions determination unit (elapsed t ≧ t _SET?)
Is selected, and an exponential function is fitted to the voltage-time data pair stored in the memory space. The form of the fitted exponential function is V = Alog (t) + B
It is. Here, A and B are constants. In the next step, a time value of 10 ³ seconds or more is substituted for V = Alog (t) + B, and a V _OCV value that closely approximates the open circuit voltage is obtained.

In the final step in this branch, this open circuit voltage value is substituted into an expression that expresses the relationship between the open circuit voltage and the battery capacity defined by the minimum current that can drive the battery drive device. This equation is generally expressed as capacitance = M [a + bV
_OCV + c (V _OCV ) ² +. . . ], A, b,
c, etc. are constants. In this example, M is a constant. However, M can be treated as a variable that changes with repeated use if effective information about the change in battery capacity with repeated use can be obtained. The new capacity is capacity = M [a + bV _OCV + c (V _OCV )
² +. . . ], The value is stored in an appropriate register and displayed by the display circuit described above.

Then, the process goes through the open circuit voltage branch and moves to the main routine of the program.

A schematic flowchart of the right branch in FIG. 7 is shown in the upper part of FIG. A more detailed flowchart of the program steps in this coulometer branch is shown in the lower part of FIG. In the first step after entering this branch,
An average current i and a temperature T during a certain measurement time interval Δt are measured. The measured temperature T is expressed by the Peukert equation Δt ₂ = Δt ₁ (i ₁ /
i ₂₎ is used to calculate the index n used in the ^n. The function of the temperature for calculating the index n is the general formula n = Α +
Β (T) + Γ (T ² ) +. . . Is represented by Α 、 Β 、
Γ, etc. are constants. Next, the correction Δt corresponding to the time interval elapsed while the battery is discharged with the lowest available current for the drive device is calculated using the Peukert equation.
The lowest available current for the battery powered device is defined as standard i, and the above-mentioned general Peukert equation is calculated as follows.

Correction Δt = Δt (i / standard i) ^{n In the} next step, the correction Δt is quadratic-dependent by temperature using a temperature correction function based on the temperature when the battery capacity is measured and defined. Make corrections. The function for calculating the new correction Δt is represented by the following general formula.

New correction Δt = correction Δt + α (T−standard T) + β (T
−standard T) ² + γ (T−standard T) ³ +. . . Where α, β, γ,
Are constants. That is, the new correction Δt uses the battery,
1) at the lowest available current for the power device; and 2) at the reference temperature at which the battery capacity is measured and defined, corresponding to the time interval that elapses between discharges. In the next step, by multiplying the lowest available current (standard i) by the time interval for performing current and temperature correction (new correction Δt), the consumption capacity (△ capacity) integrated at a fixed measurement interval is obtained. Is calculated. In the final step of this branch, △ capacity is subtracted from the existing battery capacity and the result is used as the new capacity.
Next, the data is stored in an appropriate display register by the display circuit described above. The branch of the coulometer ends, the program moves to the main routine, and the program returns to the initial step current = 0? Return to

The device constructed according to the above description was connected to a scooter equipped with a battery having a capacity of 30 Ah when fully charged. The battery is not fully charged with a sealed lead-acid battery. The scale of the display device indicates, for example, 30 Ah in a fully charged state, 15 Ah in a half state, and 0 Ah in an empty state. At the start of the scooter, the battery capacity was calculated by the open circuit voltage branch of the program to be 21 Ah.

The vehicle continuously traveled for about 20 km, during which the displayed value gradually decreased to 9 Ah. The scooter was stopped and the battery was partially charged for about one hour. After removing the battery from the charger, he ran again on the scooter. The battery capacity after charging was 18 Ah. The vehicle continued to travel about 20 km continuously, during which time the display device gradually decreased to 4 Ah. When the vehicle was stopped, the program activated the open circuit voltage branch during that time. At that time, the display output remained at 4 Ah. The battery was removed from the vehicle, and a discharge test was performed on a specially designed battery charge / discharge characteristic measuring device in a laboratory. The actual remaining capacity confirmed in the laboratory was 4.3 Ah. This means that R
The constants stored in the OM and used in the program indicate that they were appropriate for this type of battery.

(Embodiment 2) The same circuit configuration of the battery remaining capacity meter as shown in FIG. 1 of Embodiment 1 is also used in this embodiment. FIG. 10 shows a typical flowchart of a program executed by the microcomputer of the battery remaining capacity meter according to the present invention . As can be seen from FIG. 10, capacity is measured continuously from the time the battery powered device discloses operation until the end of device operation. The program has three branches. The left branch (open circuit voltage branch) operates when the current value is zero during the entire period of the _{tSET for} a certain period, and calculates a new value of the battery capacity (in other words, a new capacity). I do. In the lower part of the open circuit voltage branch, two adjacent battery capacity calculated values in time series are compared to determine whether or not the calculated value has decreased. If the capacitance value decreases, the two values are stored and the flag (FLAG) becomes 1 indicating that the two values are to be analyzed in the right branch of the program. The central main routine (coulometer branch) operates when the discharge current is a positive value other than zero, and integrates the current with respect to time to calculate the consumed capacity / capacity. Then, a new value of the battery capacity (in other words, a new capacity) is calculated by subtracting the △ capacity from the current battery capacity value. In the coulometer branch of the program, the consumed capacity and the capacity _SUB are integrated with respect to time between two battery capacity measurement times that are adjacent and decrease in time series calculated in the open circuit voltage branch. The right branch (standardized branch) is activated when the current value is non-zero and positive, and the signal FLAG indicates the presence of data and the right branch is ready for analysis. In the standardized branch, the capacity difference between two adjacent and reduced battery capacity values in time series calculated by the open circuit voltage method, the consumption capacity integrated over time between adjacent measurement times, and the capacity _SUB
Compare with The integrated consumed capacity, that is, the value of the capacity _SUB is used as a basis for adjusting the calculation function of the battery capacity value in the open circuit voltage branch of the program. As a result, the two methods are numerically consistent.

The program steps executed by the microcomputer part of the battery capacity meter according to the present invention will be described in more detail. As can be seen from FIG. 10, after the battery powered device starts operation, 1) save the program signal variable, FLAG, 2) subtotal consumption capacity, capacity _SUB , 3) voltage value, V _OLD , integrated over time. Initializes the memory space in the microcomputer. These three values are all set to zero in the initialization process. In the next step, a conditional determination is made as to whether the current is zero or not.
If the current is zero, the program enters the open circuit voltage branch. The first two steps of this branch have been described in the description of the first embodiment with reference to FIGS. If the current value changes to a non-zero value before reaching t _SET , the first condition decision statement in this branch determines NO, and the battery capacity value leaves the open circuit voltage branch without change. However, if the current remains zero for a fixed period of time t _SET , the relationship between the battery capacity and the open circuit voltage defined by the lowest available current for the battery powered device will result in a new value for the battery capacity (in other words, a new value for the battery capacity). Capacity).

This equation is a general type capacitance = M [a + bV
_OCV + c (V _OCV ) ² +. . . Where a, b,
c and the like are constants. In this example, M is a variable that is adjusted in the standardization branch that normalizes the battery capacity that changes with repeated use. New capacity is capacity = M [a + b
V _OCV + c (V _OCV ) ² +. . . After that, this value is stored in a suitable register for display by the display circuit in the same manner as described in the first embodiment.

The new capacity is calculated as follows: Capacity = M [a + bV _OCV + c (V
_OCV ) ² +. . . The next step after calculating from the above is a condition determination step. The voltage value V _OLD accumulated in the memory space is: capacity = M [a + bV _OCV + c (V _OCV ) ²
+. . . ] _Is less than or equal to the voltage value V _OCV assigned to
1) The value of V _OCV is stored as a new V _OLD , 2) The subtotal of the accumulated consumption capacity and capacity SUB is initialized to zero value, and 3) The open circuit voltage branch shifts to the main routine of the program. If the voltage value V _OLD is greater than V _OCV , the signal variable FLAG is changed to 1 to indicate that there is data to analyze for the standardized branch of the program, and the open circuit voltage branch goes to the main routine of the program. . The condition determining step in which the signal variable FLAG becomes 1 is as follows:
It means that two battery capacity values that are adjacent and decreasing in time series are measured by the open circuit voltage method. The higher of the two values is calculated by the value stored in _VOLD . The lower value is calculated by the current V _OCV .

If the current changes from zero to a non-zero value, No is selected in the condition decision statement at the beginning of the program, and the program proceeds to the central main routine (coulometer branch).
to go into. If the signal variable FLAG is equal to zero, the coulometer branch shifts to the main routine having the same program steps as in the first embodiment described with reference to FIGS. The only difference is the final step. There, the program calculates an integrated subtotal of the consumed capacity different from the current battery capacity, the capacity _SUB . The subtotal of the accumulated consumption capacity, the capacity SUB, is calculated by adding the consumption capacity, Δ capacity, which is gradually increased with respect to time, to the current value of the capacity _SUB stored in the memory space. After the completion of this step, the calculation is performed at the first condition determination step (current = 0) of the coulometer branch.
? Return to).

When the signal variable FLAG becomes 1 after the shift to the central main routine of the program, the program exits the main routine and shifts to the right branch (standardized branch). As mentioned above, the fact that the signal variable FLAG is equal to 1 indicates that adjacent decreasing battery capacity values in two time series have been measured by the open circuit voltage method and stored in memory space. When the signal variable FLAG equals 1,
It also means that the current value of the capacity _SUB is determined during the measurement interval between the battery capacity values that are adjacent and decreasing in two time series. In the first step in this standardization branch, the sub-total of the integrated consumed capacity, the capacity _SUB, and the difference between the two successively decreasing current battery capacity values obtained by the open circuit voltage method, M, are made equal. Perform new value calculations. This is expressed mathematically as:

Capacity SUB = M [a + bV _OLD + c (V _OLD ) 2 +
...]-M [a + bV _OCV + c (V _OCV ) ² + ...] By rearranging this equation, M can be easily obtained. New M
Is used to calculate the battery capacity (in other words, the new capacity).

New capacity = M [a + bV _OCV + c (V _OCV ) ²
+. . . At this point in the program, the two methods are numerically consistent. At the end of this branch, the variables in the program are reinitialized as follows. That is, 1) the value of V _OCV is accumulated in V _OLD , and 2) the signal variable FLA
G is reset to zero, and 3) the subtotal of the consumable capacity, capacity _SUB , integrated over time is reset to zero. The standardization branch then terminates and moves to the main routine of the program.

The device constructed according to the above description was connected to a scooter equipped with a battery having a capacity of 30 Ah when fully charged. The battery is not fully charged with a sealed lead-acid battery. The scale of the display device indicates, for example, 30 Ah in a fully charged state, 15 Ah in a half state, and 0 Ah in an empty state. At the start of the scooter, the battery capacity was calculated to be 26 Ah by the open circuit voltage branch of the program.

When the vehicle continuously traveled for about 30 km, the displayed value gradually and stably decreased to 9 Ah during that time. The scooter was stopped and the battery was partially charged for about 2 hours. After removing the battery from the charger, he ran again on the scooter. The battery capacity after charging was 24 Ah. The vehicle continued to travel about 20 km continuously, during which time the display device gradually decreased to 6 Ah. When the vehicle was stopped, the program activated the open circuit voltage branch during that time. At that time, the display output remained at 6 Ah. The battery was removed from the vehicle, and a discharge test was performed on a specially designed battery charge / discharge characteristic measuring device in a laboratory. The actual remaining capacity confirmed in the laboratory was 6.1 Ah.
This indicates that the constants stored in the ROM and used in the program were appropriate for this type of battery.

The scooter was then run for several months under normal conditions, and the same tests were repeated. The battery capacity in the fully charged state was reduced to 25 Ah. At the beginning of the second test, the capacity was measured at 23 Ah by the open circuit voltage section of the program.

When the vehicle was continuously driven for about 10 km, the indicated value was gradually and gradually reduced to 17 Ah. When the vehicle was stopped, the program activated the open circuit voltage branch during that time. At that time, the display output remained at 17 Ah. The battery was removed from the vehicle, and a discharge test was performed on a specially designed battery charge / discharge characteristic measuring device in a laboratory. The actual remaining capacity confirmed in the laboratory is 16.
9Ah. This means that the R
It means that the constants stored in the OM were well matched to the battery and that the standardization branch of the program worked as expected.

[0042]

[0043]

[0044]

As described above, the present invention is based on an open-circuit voltage type battery state of charge meter that functions only when the current value is zero for a certain period of time, and continuously when the current is a positive value instead of zero in the discharge direction. Combining the beneficial features of a coulometric battery-capacity meter that functions in a single way, it provides a single battery-capacity meter that cancels out the disadvantages of both and combines the advantages of both. Simple to compensate for battery aging
Means are included in the battery capacity meter.

[0045]

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a battery state of charge meter according to the present invention.

FIG. 2 is a diagram showing constant current discharge characteristics of a battery.

FIG. 3 is a diagram showing a relationship between a common logarithm of a discharge current and a common logarithm of a discharge duration.

FIG. 4 is a diagram showing a relationship between a discharge current value and a dischargeable capacity.

FIG. 5 is a diagram showing a relationship between a cycle number and a dischargeable capacity.

FIG. 6 is a diagram showing the relationship between open circuit discharge voltage and dischargeable capacity.

FIG. 7 is a flowchart of a program control (claim 1) by a microcomputer of the battery remaining capacity meter of the present invention.

FIG. 8 is a flowchart of a program control (claim 3) by the microcomputer of the battery state of charge meter according to the present invention.

FIG. 9 is a flowchart of a program control (claim 4) by the microcomputer of the battery remaining capacity meter of the present invention.

FIG. 10 is a flowchart of a program control (claim 2) by the microcomputer of the battery state of charge meter according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery terminal voltage detection circuit Battery discharge current detection circuit Battery temperature detection circuit 5 Low pass filter 6, 7, 8 Sample hold A / D converter Microcomputer ROM Latch Pointing device 14 LED module

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-135303 (JP, A) JP-A-4-363679 (JP, A) JP-A-4-134280 (JP, A) JP-A-61- 209372 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 31/36

Claims (4)

(57) [Claims] 1. A voltage measuring <br/> means for measuring a terminal voltage of the battery, current measuring means for measuring the terminal current of the battery, a temperature measuring means for measuring the temperature of the battery, the terminal voltage and
Calculating means for calculating the remaining capacity from the terminal current and temperature, storage means for storing the calculation result, it has a display means for displaying the calculation result, the calculation unit, when the current is constant time zero
An open circuit voltage is estimated based on the terminal voltage,
According to a polynomial relating the open circuit voltage and the remaining capacity,
First calculating means for calculating the remaining capacity of the battery;
When a zero or more current flows in the discharge direction of the battery,
Subtracting the integrated value of the terminal current from the current remaining capacity
And second calculating means for calculating the remaining capacity by
In the remaining battery capacity meter of the battery-powered devices that will be, the polynomial said first computing means is used, the battery-powered
The battery has a constant current with the minimum current that can drive the power device.
And a polynomial expressed assuming that the battery is discharged in a discharge manner, wherein the calculating means calculates the remaining capacity of the second calculating means.
With the calculation process in between, the remaining capacity by the first calculation means
When the calculation processing of (1) is executed twice, the first calculation
The difference value of the remaining capacity between the new and old two times calculated by
The decrease in the remaining capacity during the processing period of the second calculation means
Compare the quantities and use them in the polynomial so that they are equal.
A battery remaining capacity meter characterized in that a required coefficient is obtained. 2. The method according to claim 1, wherein the second calculating means calculates the terminal current.
Integral value, the terminal current value during the integration period and
The battery remaining capacity meter according to claim 1, wherein the correction is performed based on the temperature . Wherein the first calculating means accumulates the time and voltage data to the memory device, the relationship pickled combinations of time and voltage data accumulated in a logarithmic function with a logarithmic function of its 10 ³ seconds according to claim 1 or claim 2 battery capacity meter according to, characterized in that is adapted to calculate the open-circuit voltage values for the above time values. Wherein said second calculating means measures the average current and temperature for a predetermined time, measuring with a Peukert equation having the corresponding index to the constant temperature, the lowest current available corrected by a current value calculating a corresponding time, using a temperature correction function to make the standard temperature when measuring battery-capacity, calculate the time corresponding to the lowest current that can be used corrected by the temperature, at standard temperature by applying a correction time by current and temperature to the lowest available current value, there remaining battery that 請 Motomeko 2 wherein you <br/> characterized adapted to integrate the exhaustion capacity at a certain time Capacity meter.