JP2791751B2 - Remaining capacity meter and method for evaluating remaining capacity of lead-acid battery for electric vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention mainly relates to a current integrating method.
Remaining lead-acid battery for electric vehicles using internal resistance detection
Regarding the improvement of the capacity meter and the remaining capacity evaluation method,
Internally executed when full charge is completed and when the vehicle is temporarily stopped
Each measurement is made from the internal resistivity defined and calculated based on the resistance measurement.
Obtain the discharge rate at a fixed point in time, and use the current
Lead for electric vehicles corrected for estimation of storage capacity
The present invention relates to a remaining capacity meter and a remaining capacity evaluation method for a storage battery .

[0002]

2. Description of the Related Art Since electric vehicles have high energy utilization efficiency, the remaining capacity of storage batteries is greatly affected by driving conditions. Therefore, the storage battery remaining capacity meter is an indispensable device for estimating the remaining mileage, and the remaining mileage can be estimated in consideration of the running conditions after the accurate knowledge of the remaining storage capacity is obtained. It has been desired.

[0003] In the conventional voltage detection type storage battery remaining capacity meter, since the capacity of the storage battery is affected by the running state (voltage fluctuations during running, etc.) and the remaining capacity display always changes, it is difficult to determine the remaining capacity and the life of the storage battery. , Did not lead to gaining practical accuracy.

[0004] In addition, the life of a lead storage battery is significantly shortened when it is discharged to 80% or more of the total capacity. Therefore, there is a need for a method for accurately and accurately detecting the usable capacity of a point storage battery which is 80% of the total capacity.

Under these circumstances, the applicant of the present invention has previously disclosed an "electric vehicle" capable of displaying, with high accuracy, a remaining possible travel distance predicted according to a traveling state (traveling mode) in a remaining traveling section by a current integration method. For the remaining travelable distance meter. " (Japanese Patent Application No. 4-355200)

Further, there has been proposed a "battery state display device for electric vehicles" which displays the state of charge of the storage battery from the start of traveling and can calculate the state of charge of the storage battery according to the actual running state of the electric vehicle. . (JP-A-3-1353)
No. 03)

[0007] Further, there has been proposed a "data storage device" which is attached to an electric vehicle and can be used as a remaining capacity meter of a storage battery or a life determining device. (See JP-A-3-17966)

[0008]

However, although there are suggestions to be taken in the analysis of the actual running state (driving results) and the use state of the storage battery, there has been no new method of voltage detection. That is, the sequential data of the storage battery still reflects the voltage fluctuation during running, and there is a subject in obtaining the storage battery remaining capacity and the total running data (history) after the actual running correction.

[0009] The earlier proposal of the present applicant is also close to this subject, and is not affected by voltage fluctuation during traveling.
The task of knowing the remaining capacity of the storage battery with extremely high accuracy has been left. Furthermore, since the total capacity of the storage battery cannot be grasped, there is also a problem that it is not possible to determine the point storage battery usable capacity which is 80% of the total capacity.

[0010] The present invention has been made in view of such circumstances, and solves the above-mentioned problems relating to improvement in accuracy , and provides a fully charged battery.
Of the internal resistance that is executed when the
Each measurement point from the internal resistivity defined and calculated based on the measurement
Battery discharge capacity by the current integration method
Lead-acid battery for electric vehicles that corrects the estimation calculation
It is an object of the present invention to provide a remaining capacity meter and a remaining capacity evaluation method .

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method which is carried out when a full charge is completed and when a vehicle is temporarily stopped.
The internal resistance defined and calculated based on the measured internal resistance
The discharge rate at each measurement point is obtained from the drag coefficient, and the current integration method is used.
Of the estimated remaining battery capacity
It is a remaining capacity meter of a lead-acid battery for an electric vehicle, and is configured of a measuring unit connected to a cable, a display circuit unit, and a display LED unit, wherein the measuring unit has an analog circuit unit and a digital circuit unit, and the analog circuit portion is resistance
Forced discharge circuit by a resistor, voltage drop during forced discharge and
Internal resistance detection means consisting of a differential circuit for detecting a current change
It is characterized by having .

[0012] Here, the digital circuit portion of the configuration is stored in the calculation program ROM, calculation means for calculating the quantities relating to the storage battery available capacity based on the measured data of the main storage battery incorporated into the analog circuitry When,
The display circuit unit has a serial data transmission unit for transmitting the result to the display circuit unit, the display circuit unit has a maintenance terminal for enabling to update various setting data input from an external computer, the display LED unit, It has a display panel for receiving a signal from the display circuit unit and updating / displaying at least the battery capacity, the travelable distance, and the battery replacement time.

Further , the remaining capacity meter is used as a technical means.
Of residual capacity of lead-acid battery for electric vehicle
Method, when full charge is completed and when driving
Activate the forced discharge circuit several times instantly,
Voltage drop and current change via
From these, the average value of the internal resistance is calculated, and when the full charge is completed
At the time of the suspension with respect to the internal resistance value calculated and stored in
The ratio of the internal resistance is defined and calculated as the internal resistivity.
The discharge rate at each measurement point corresponding to the internal resistivity is
To obtain a current integration method using the discharge rate.
To estimate the remaining battery capacity estimation calculation
It is characterized by the following.

[0014]

The present invention measures the current, voltage, temperature and internal resistance of the battery (calculated from the amount of voltage change and the amount of current change during forced discharge) and processes digital data to calculate the capacity of the battery.

The total capacity of the storage battery at a certain point in time is represented by A [Ah].
Then, the actually usable storage battery capacity (point storage battery usable capacity) is A × 0.8 [Ah] from the condition introduced in the above-described conventional technique.

Therefore, the point storage battery usable capacity (0.8 A) is in the range of 100 to 30% (ie, discharge rate 0 to 0).
(70%) is obtained by finely integrating the discharge current of the storage battery and subtracting it from the storage battery capacity for display. (Current integration method)

Further, a range of 30 to 0% (ie, discharge rate 70
〜100%), the internal resistance of the storage battery is measured, the usable capacity of the point storage battery is obtained, and the remaining capacity obtained by the current integration method is corrected and displayed. (Internal resistance detection method)

That is, when the ignition key is turned on or when the vehicle is stopped, it is determined that no current is flowing, the internal resistance of the storage battery is measured each time, and the ratio of the measured internal resistance to the internal resistance at full charge ( Internal resistivity; see definition below)
However, when it is less than 1.2, the remaining capacity is calculated by the current integration method, and when it is 1.2 or more, the remaining capacity is calculated and displayed from the relation table between the internal resistivity and the remaining capacity (FIG. 4 described later). I do.

Further, the obtained remaining capacity is divided by the electricity consumption rate per km to digitally display the remaining travelable distance. Then, when the capacity at the time of full charge becomes 50% or less of the rated capacity, an alarm is displayed.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in the following order with reference to the accompanying drawings. 1 Outline of hardware 2 Outline of operation 3 Outline of software 3-1 Algorithm 3-1-1 Basic policy 3-1-2 Definition and symbol of each term 3-1-3 Calculation of remaining capacity 3-1-4 Self Discharge 3-1-5 Aging 3-1-6 Display method of remaining capacity 3-1-7 Display method of remaining mileage 3-1-8 Display method of battery replacement timing alarm 3-2 Internal resistance due to forced discharge Method for estimating full charge capacity and remaining capacity of main battery from measurement

[0021] 1 Hardware Overview Figure 1 is a device configuration schematic diagram according to an embodiment of the present invention,
FIG. 2 is an external view of the same. Here, 1 is the main storage battery, 2
Is a measurement unit, 3 is a display circuit unit, 4 is a display LED unit, 5 is an analog circuit unit, 6 is a digital circuit unit, 7 is an internal resistance detecting unit, 31 is a maintenance terminal (connected to an external computer), 41 is a display panel, 61 is a ROM, 62 is a calculation means (CPU), 63 is a serial data transmission means (SIO),
71 is a forced discharge circuit, 72 is a differentiation circuit, and X is a lead storage battery remaining capacity meter for an electric vehicle (the device of the present invention).

As shown, the device (X) of the present invention comprises a measuring unit (2), a display circuit unit (3) and a display LED unit (4).
The measurement unit (2) is divided into an analog circuit unit (5) and a digital circuit unit (6).

Each measurement data of current, voltage and temperature is taken from the main storage battery (1) of the electric vehicle (side) into the analog circuit section (5) via the insulating amplifier. In the digital circuit section (6), a 16-bit CPU (H8 / 536) (62)
, And serially transmitted to the display circuit (3) (63)
Then, the display LED unit (4) updates and displays the battery capacity and the possible travel distance every second.

The measuring section (2) has a forced discharge circuit (7
1) is provided, the voltage change and the current change are detected by the differentiating circuit (72), and the internal resistance of the main storage battery (1) is measured.
It is reflected in the calculation of battery capacity and travelable distance. The calculation program is stored in the ROM (61).

A maintenance terminal (31) is provided in the display circuit section (3), and a personal computer can be connected from the outside to update various setting data used for calculation. The display program is stored in the ROM inside the display CPU.

The display LED section (4) detects the external brightness and automatically adjusts the brightness of the LED.

2. Outline of Operation An outline of the operation of the device of the present invention will be described below in (1) to (6). (1) After the first full charge is completed, turn on the ignition key and press the reset button of the measurement unit for 2 seconds or more. When the battery capacity of the display LED unit is 100% and the travelable distance is 60 km (current consumption during traveling is 2.0 Ah) / Km to battery capacity 120Ah
Is displayed).

(2) After confirming the above (1), when the ignition key is turned off, the display LED section is turned off.

(3) Thereafter, when the ignition key is turned on,
The battery capacity and the mileage are displayed and updated every second.

(4) During running or charging, the current value is finely integrated to determine the battery capacity. When no current is flowing through the main storage battery when the ignition key is turned on or stopped at the start, an instantaneous current is forcibly applied to the resistance load in the measuring unit, and the internal resistance is measured to update the battery capacity.

(5) When the ignition key is OFF and no current flows through the main storage battery and the vehicle is parked for a long time, the amount of self-discharge is calculated and the battery capacity is reduced. The self-discharge coefficient uses the value input from the maintenance terminal.

(6) The number of times of charge / discharge use is measured, the aging deterioration amount is calculated, and the full charge amount is reduced. The aging coefficient uses the value input from the maintenance terminal.

3. Software Overview The software algorithm for displaying the remaining capacity of the lead-acid battery for an electric vehicle, the mileage, and the warning of the battery replacement time by the CPU of the device of the present invention is based on the current integration method. The correction is performed using the resistance detection method together. The algorithm will be described below.

3-1 Algorithm 3-1-1 Basic Policy Since the life of a lead storage battery is significantly deteriorated when it is discharged to 80% or more of the rated capacity, the point of time of 80% discharge (the usable capacity of the point storage battery described above) is accurately detected. At that time, the remaining capacity display of the meter must be set to zero.

The lead storage battery is used under the following conditions (battery temperature,
Since the retrievable electric energy (usable capacity of the storage battery) greatly changes depending on the charging / discharging current, the amount of the internal electrolytic station, etc., it is necessary to constantly correct the available capacity of the storage battery. Therefore, the current integration method and the internal resistance detection method are used together to calculate the remaining capacity of the storage battery, and the calculation accuracy of the remaining capacity of the storage battery is increased.

That is, up to the range of 100 to 30% of the usable capacity of the point storage battery, the discharge current of the storage battery is finely integrated and subtracted from the storage battery capacity (current integration method) and displayed. The resistance is measured (internal resistance detection method) and the remaining capacity obtained by the current integration method is corrected and displayed.

3-1-2 Definitions and Symbols of Each Term Hereinafter, the terms (1) to (13) are listed. (1) Remaining capacity [Ah]: Refers to the remaining capacity of the storage battery. (2) Full charge capacity [AhF]: The full capacity when the storage battery is fully charged. (3) Minimum storage battery remaining capacity: The lower limit capacity that must always be left. Usually 20% of the rated capacity of the storage battery
And (In the case of a storage battery with a rated capacity of 150 Ah, the minimum remaining capacity of the storage battery is 30 Ah.) (4) Maximum usable capacity of the storage battery: a value obtained by subtracting the minimum remaining battery capacity from the full charge [AhF]. (5) Storage battery usable capacity: A value obtained by subtracting the minimum storage battery remaining capacity from the remaining capacity [Ah]. (6) Full charge: When the storage battery is charged, it is determined that the battery is fully charged when the terminal voltage per storage battery is 15 V or more and the charging current is 9 A or less. (7) Running: A state in which a current of 2 A or more flows from the storage battery in the discharging direction. (8) During suspension: A state in which the storage battery current is 0 to 2 A or less has continued for 2 seconds or more. (9) Reference internal resistance [R0]: An internal resistance measured immediately after the completion of full charge. (10) Internal resistivity [Rr]: A value obtained by dividing the internal resistance [Rt] measured during stoppage by the reference internal resistance [R0]. (11) Discharge rate [α]: A value obtained by dividing the amount of discharge by the maximum usable capacity of the storage battery. (12) Amount of self-discharge: The amount of self-discharge when the ignition key is turned off, which is 0.75 Ah per day
And However, this self-discharge amount is a set value that can be arbitrarily changed from the maintenance terminal. (13) Aging deterioration amount [kd]: The amount by which the full charge capacity decreases with the number of times of charging / discharging of the storage battery.
5Ah. However, the aged deterioration amount is a set value that can be arbitrarily changed from the maintenance terminal.

3-1-3 Calculation of Remaining Capacity (1) At the time of installation (including at the time of replacement of the main storage battery) At the time of installation, the storage battery of the electric vehicle must be fully charged. At this time, the full charge capacity and the remaining capacity are set to 150 Ah regardless of the degree of deterioration of the storage battery, and the self-discharge amount and the aging deterioration amount are set to 0.

(2) Running and Stopping The remaining capacity is calculated by the current integration method. The calculation formula is shown in the following formula <1>. <1> Ah (t) = Ah (0) −Σ (kd · id · Δt) +
Σ (kr · ir · Δt) where Ah (t): remaining capacity at time t [A
h] Ah (0): Remaining capacity at time 0 [Ah] Σ (id · Δt): Electricity used from time 0 to t Σ (kr · ir · Δt): Regenerative braking from time 0 to t Charged electricity amount id: discharge current value kd: discharge current coefficient ir: regenerative braking current value kr: regenerative braking current coefficient (0.8 to 0.9); arbitrarily changeable

The number of times the current value is sampled is 5000 samplings per second, and the integrated value of the 5000 samplings is the current value per second. i. e. I = Σi · Δt I: Current value every second [A] i: Instantaneous value of current [A / S] Δt: Sampling interval (0.2 mS)

(3) Correction of Full Charge Capacity and Remaining Capacity Immediately after Stopping Once immediately after the stop, the internal resistivity [R
r], the remaining capacity [Ah] and the full charge capacity [AhF] at that time are corrected by the method of 3-2 described later.

(4) At the time of charging At the time of charging, it is basically calculated by the current integration method. Expression <
2> shows a formula for calculating the remaining capacity [Ah] during charging. <2> Ah (t) = Ah (t ₁ ) + Σ (kc · ic · Δt) where Ah (t): remaining capacity at time t [A
h] Ah (t ₁ ): remaining capacity at time t ₁ [Ah] Σ (kc · ic · Δt): amount of electricity charged by the charger from time t ₁ to t ic: charging current value kc: charging current Coefficient [0.8 to 0.9] (can be changed arbitrarily from the maintenance terminal)

However, if the remaining capacity at the time of charging exceeds the full charge capacity of the meter at that time, the remaining capacity is the same as the full charge capacity.

Although the full charge condition is satisfied at the time of charging,
If the remaining capacity does not reach the full charge capacity of the meter at that time, the remaining capacity at that time is regarded as the full charge capacity, and it is assumed that the meter is fully charged.

If the full charge condition is not satisfied at the time of charging and the remaining capacity does not reach the full charge capacity of the meter at that time, the full charge capacity is not updated and the remaining capacity is the current capacity. .

3-1-4 Self-discharge The self-discharge amount is obtained by measuring the time during which the ignition key is left in an OFF state in minutes, and calculating the self-discharge amount per minute (0.75 / The value multiplied by (24 × 60) is subtracted from the remaining capacity when the ignition key is turned on next time. However, it is assumed that there is no self-discharge during charging, and the self-discharge amount is not counted even when the ignition key is turned off.

3-1-5 When the accumulated aging discharge amount exceeds the full charge capacity, the aging deterioration amount kd (0.15 Ah / time) is calculated from the full charge capacity AhF (t−1) inside the meter at that time. ) Is taken as the new full charge capacity AhF (t).

The total discharge amount is set to 0 when the full charge capacity is updated, and the total discharge amount is newly started from that point. i. e. AhF (t) = AhF (t-1) -kd AhF (t): Updated full charge capacity AhF (t-1): Full charge capacity inside the meter at that time kd: Aged deterioration amount

3-1-6 Display Method of Remaining Capacity The display of the remaining capacity indicates that the maximum usable capacity of the storage battery is 100%.
The ratio of the available capacity of the storage battery to the maximum available capacity of the storage battery is indicated by 10 LEDs at 10% intervals.
Green display is performed between 0 and 100%, and red display is performed when 0% or less.

3-1-7 Display Method of Remaining Drivable Distance A value obtained by dividing the available capacity of the storage battery by the electricity consumption rate is displayed as a numerical value in km. The electric consumption rate uses the numerical value shown in Table 1 in which the average electric consumption rate determined from the results of the running test on the chassis dynamo of the electric vehicle owned by the present applicant is divided into up to three sections based on the remaining capacity. I do.

[0051]

[Table 1]

3-1-8 Display Method of Battery Replacement Timing Alarm
The legal storage battery replacement timing warning indicates that the full charge capacity is 75
This is displayed when the state of Ah or less is continuously continued 10 times or more.

Table 2 shows each coefficient used in the above algorithm.
Table 3 shows the operation modes in which the calculation formulas are classified by each external event. In addition, the storage battery (ED
FIG. 3 shows a graph of the discharge characteristics of ten in series of −150).

[0054]

[Table 2]

[0055]

[Table 3]

3-2 From Measurement of Internal Resistance by Forced Discharge
Method for Estimating Full Charge Capacity and Remaining Capacity of Main Storage Battery The procedure is described below in (1) to (4). (1) Immediately after the completion of full charge, instantaneous forced discharge is performed 10 times, and the average internal resistance is defined as a reference internal resistance R0. (The time required for 10 instantaneous forced discharges is 200 mS)

(2) When the main storage battery current is within 0 to 2 A for 2 seconds or more, the instantaneous forced discharge is performed once as one sample, and the main storage battery internal resistance R is calculated from the average value.
t is determined and the internal resistivity is determined.

(3) At this time, the internal resistivity [Rr] is 1.
When the value becomes 2 P.U. or more, a discharge rate table (see FIG. 4) showing the relationship between the internal resistivity previously determined in the experiment and the ratio α of the discharge amount up to that point relative to the full charge capacity (hereinafter referred to as the discharge rate). With reference to 4), the discharge rate αt is obtained. When the internal resistivity [Rr] is 1.2 P.U. or less, neither the full charge capacity AhF (t) nor the remaining capacity Ah (t) is corrected.

(4) Based on the discharge rate αt, the full charge capacity and the remaining capacity are corrected as shown in (a) and (b) below.

(A) Method of Estimating Full Charge Capacity Assuming that the full charge capacity is AhF (t), its calculation formula is shown below. AhF (t) = Σid (t) / αt where, Σid (t): amount of discharge until that time (time t) αt: discharge rate

(B) Method of estimating the remaining capacity The remaining capacity is represented by Ah (t), and its calculation formula is shown below. Ah (t) = (full charge capacity) − (discharge amount discharged up to that time) = AhF (t) −Σid (t) = (1 / αt) Σid (t) −Σid (t) = ｛(1− αt) / αt｝ Σid (t)

[0062]

According to the present invention, the remaining capacity can be displayed with high accuracy even during traveling. Therefore, the driver can travel with peace of mind and drive up to the full battery capacity, so that the utilization rate of the electric vehicle can be improved.

In addition, since the existing electric vehicle can be easily mounted without modification, and is small and inexpensive, it can be expected to contribute to the spread of electric vehicles.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a device configuration according to an embodiment of the present invention.

FIG. 2 is an external view of the same.

FIG. 3 is a graph (data plot) of a discharge characteristic of a storage battery (example) on which an algorithm of the present invention is based.

FIG. 4 is a data plot showing a relationship between an internal resistivity and a discharge rate used by the apparatus of the present invention as a discharge table.

[Explanation of symbols]

Reference Signs List 1 Main storage battery 2 Measurement section 3 Display circuit section 4 Display LED section 5 Analog circuit section 6 Digital circuit section 7 Internal resistance detection means 31 Maintenance terminal (external computer connection) 41 Display panel 61 ROM 62 Calculation means (CPU) 63 Serial data transmission Means (SIO) 71 Forced discharge circuit 72 Differentiation circuit X Lead-acid battery remaining capacity meter for electric vehicles (device of the present invention)

Continuation of the front page (72) Inventor Norihiro Okubo 4-33 Komachi, Naka-ku, Hiroshima City, Hiroshima Prefecture Inside Chugoku Electric Power Company (56) References JP-A-5-341022 (JP, A) JP-A-5-180912 (JP, A) JP-A-4-368401 (JP, A) JP-A-6-43225 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60L 3/00 B60L 11 / 18 G01R 31/36 H01M 10/48

Claims (3)

(57) [Claims] An internal resistance is detected using a current integration method as a main method.
Capacity meter for lead-acid batteries for electric vehicles using a new method
To be executed at the time of full charge completion and suspension during driving
Each measurement is made from the internal resistivity defined and calculated based on the resistance measurement.
Obtain the discharge rate at a fixed point in time, and use the current
Lead for electric vehicles corrected for estimation of storage capacity
A remaining capacity meter for a storage battery, comprising a measuring unit, a display circuit unit, and a display LED connected to a cable.
The measuring section has an analog circuit section and a digital circuit section, and the analog circuit section has a forced discharge circuit using resistors and a voltage drop at the time of forced discharge.
And internal resistance detection consisting of a differential circuit that detects current changes
Of a lead-acid battery for electric vehicles characterized by having means for
Remaining capacity meter. 2. A digital circuit section executes an operation program by an RO.
M for calculating various quantities related to the available capacity of the storage battery based on each measurement data of the main storage battery stored in the analog circuit unit and transmitting serial data for transmitting the result to the display circuit unit Means, a display circuit section having a maintenance terminal for updating various setting data input from an external computer, a display LED section receives a signal from the display circuit section, and has at least a battery capacity and Updated mileage and battery replacement time
2. A display device having a display panel for displaying.
A lead-acid battery remaining capacity meter for an electric vehicle as described in the above. 3. An internal resistance detection method mainly using a current integration method.
Of residual capacity evaluation method for lead-acid batteries for electric vehicles
For improvement, a forced discharge circuit is provided when full charge is completed and when the vehicle is temporarily stopped during driving.
Activated multiple times instantly, each time through the differentiator circuit
Detects drops and current changes, and
Calculate the average value of the resistance and calculate and store it when the full charge is completed.
Of the internal resistance value at the time of the pause with respect to the
The ratio is defined and calculated as the internal resistivity, and this internal resistivity
Look up the discharge rate at each corresponding measurement point from the data table
Obtain and use the discharge rate to determine the remaining battery by the current integration method.
Characterized in that so as to correct the estimated calculation of the volume
Method for evaluating the remaining capacity of lead-acid batteries for electric vehicles.