JP2002249006A - Method and device for measuring battery pure resistance for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for measuring battery pure resistance for a vehicle capable of measuring pure resistance of a battery even during a use of a vehicle. SOLUTION: A terminal voltage and a discharge current when a discharge current flows from a battery are periodically measured by a voltage.current measuring means 23a-1, and a first approximate curve formula for voltage- current characteristics to an increasing discharge current and a second approximate curve formula for a voltage-current characteristics to a decreasing discharge current are determined by an approximate curve formula calculating means 23a-2. A computing means 23a-3 determines two linear formulas indicating a change of synthetic resistance presented by the battery to the increasing discharge current and the decreasing discharge current by respectively differentiating the two approximate secondary curve formulas. Two values corresponding to the maximum values of the determined the discharge currents of the two linear formulas are determined. A value obtained by multiplying a value, obtained by adding the determined two values, by 1/2 is measured as pure resistance of the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the pure resistance of a battery mounted on a vehicle for supplying power to a load of the vehicle.

[0002]

2. Description of the Related Art Generally, when a current is discharged from a battery, a terminal voltage of the battery drops. The voltage drop is due to the internal impedance (combined resistance) of the battery, but the IR loss (pure resistance, that is, the voltage drop due to ohmic resistance) due to the structure of the battery and the polarization resistance due to the chemical reaction. It can be divided into voltage drops due to components (activation polarization, concentration polarization). When the voltage-current (VI) characteristic is obtained, the voltage drop due to the IR loss does not change if the state of the battery is the same, but the voltage drop due to the polarization resistance component is the magnitude of the current and the current is discharged. It changes with time. Therefore, it can be seen that inferring various states of the battery from the VI characteristics including the polarization resistance component results in an inaccurate estimation result. Therefore, a technique for measuring only the pure resistance separated from the polarization resistance component is necessary. It is said.

[0003] In addition, the battery can be used repeatedly within the range of its charge capacity by charging the battery to cover the discharge current. However, if an unexpected situation such as overdischarge or insufficient electrolyte is caused, Of course, even if these situations do not occur, if the battery is used for a long period of time and changes over time, the dischargeable capacity, which is the amount of power that can be supplied to the load by discharging, rapidly decreases. For this reason, in a state where the dischargeable capacity is reduced due to aging, even if a discharge exceeding the charge occurs for a short period of time, the starter motor can be started after the engine is stopped and the engine cannot be restarted. Absent.

Incidentally, it is known that when a new battery is compared with a battery that has undergone aging, the battery that has undergone aging has a higher net resistance than a new battery. For this reason, it has been considered to measure the pure resistance of the battery as a guide for battery replacement at the time of periodic inspection of the vehicle or the like. This is by knowing the net resistance
This is because the degree of deterioration can be determined in consideration of the ratio between the pure resistance and the polarization resistance component. Also, knowing the pure resistance can be used to estimate the open circuit voltage of the battery.

Conventionally, in a measuring instrument generally used for measuring the pure resistance of a battery, when the battery is in a static state, that is, when the battery is charged or discharged, a voltage rise or a voltage drop such as polarization occurs in the electrolyte. The battery's net resistance is being measured when it is in equilibrium where it has not occurred. (Delete.)

[0006] As an example, 1 kHz to 1
A method of obtaining a pure resistance from a relationship between a voltage and a current that changes within a certain time of, for example, about 1 μs in a situation where charging and discharging are repeated by applying an alternating current of about 00 kHz and neither polarization of charging nor discharging is accumulated. There is. This is because, as shown in FIG. 10, after the discharge is stopped, the voltage rapidly recovers and then gradually recovers.
It is considered that a sudden voltage recovery within t is caused only by the component due to the pure resistance R, and that a gradual change thereafter is caused by components (capacitance and inductance components) other than the pure resistance, including polarization, other than the pure resistance.
The purpose of the present invention is to measure a change in voltage and current within a short time of each application cycle of an alternating current having a frequency of about 100 kHz to measure a pure resistance.

[0007]

However, when a battery mounted on a vehicle is used as a target, a static state exists only in a limited case, and is applicable when the vehicle is in use. Can not.

In the case of the above-mentioned example, since it is necessary to collect data of the voltage V and the current I within a short time, it is necessary to perform A / D conversion by performing sampling with a very short period within a fixed time Δt. Although it must be performed, it can be realized as a measuring device used alone, but it is very difficult to use it mounted on a vehicle. In addition, in order for the required ΔV / ΔI to be accurate, each of ΔV and ΔI must indicate a large value, but such a vehicle can be measured only in limited cases. Furthermore, any alternating current cannot be applied to the battery during vehicle operation. Therefore, there is a reality that the method of the above-described example cannot be applied to measure the pure resistance of the battery while the vehicle is in use.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method and an apparatus for measuring a battery pure resistance of a vehicle, which can measure the pure resistance of the battery even when the vehicle is in use.

[0010]

In order to achieve the above object, the present invention according to any one of claims 1 to 3 relates to a method of measuring a battery pure resistance for a vehicle, and claims 4 to 6.
The described invention relates to a vehicle battery pure resistance measuring device.

[0011] The present invention has been made to solve the above problems.
The invention described in a vehicle battery pure resistance measuring method for measuring the pure resistance of a battery mounted on a vehicle to supply power to a load of the vehicle, wherein the load monotonically increases beyond a predetermined value and is increased from a maximum value to a predetermined value. A voltage-current characteristic for the increasing discharge current, which periodically measures the terminal voltage and the discharge current of the battery when a discharge current that monotonously decreases below the value flows and indicates a correlation between the terminal voltage and the discharge current. And a second approximate quadratic curve equation of the voltage-current characteristic with respect to the decreasing discharge current, and differentiating the two approximate quadratic curve equations, Two linear equations showing the change in the combined resistance exhibited by the battery with respect to the increasing discharge current and the decreasing discharge current are determined, and between two values corresponding to the maximum value of the determined two linear equations. It consists in the vehicle battery pure resistance measuring method and measuring the net resistance as there is a pure resistance in the combined resistance presented by the serial battery.

According to the first aspect of the present invention, the discharge current is supplied from the battery to the load of the vehicle, and the load of the vehicle monotonically increases beyond a predetermined value and monotonically decreases from the maximum value to a predetermined value or less. Periodically measures the terminal voltage and the discharge current of the battery when the current flows, and decreases the first approximate curve expression of the voltage-current characteristic with respect to the increasing discharge current showing the correlation between the terminal voltage and the discharge current. A second approximate curve expression of the voltage-current characteristic with respect to the discharge current is obtained.

Next, the two approximate quadratic curve equations obtained are differentiated to obtain two linear equations indicating the change in the combined resistance exhibited by the battery with respect to the increasing discharge current and the decreasing discharge current. .

Thereafter, the pure resistance is measured on the assumption that there is a value of the pure resistance in the combined resistance exhibited by the battery between the two values corresponding to the maximum values of the two obtained linear expressions. The resistance value measured in this way agrees well with the resistance actually measured by another method, which means that the slope of the voltage-current characteristic due to only the resistance actually measured by the other method is different from the one at the point of the maximum value. Can be understood from the fact that the slope of the tangent at the maximum value of the voltage-current characteristic with respect to the increasing discharge current is smaller than the slope of the tangent at the maximum value of the voltage-current characteristic with respect to the decreasing discharge current. Therefore, it is necessary to measure the terminal voltage and the discharge current of the battery when power is supplied to the load in a normal use state of the vehicle, and to process the data obtained as a result of the measurement to measure the pure resistance of the battery. Can be.

According to a second aspect of the present invention, in the vehicle battery pure resistance measuring method according to the first aspect, a value at an intermediate point between the two values is measured as the pure resistance. It consists in resistance measurement method.

According to the above-described procedure of claim 2, 2
Since the value at the midpoint between the two values is measured as pure resistance,
For example, the pure resistance can be measured by a simple operation of multiplying the value obtained by adding two values to 乗.

The third aspect of the present invention is the first or second aspect.
In the method for measuring a battery pure resistance for a vehicle according to the present invention, in obtaining the first approximate curve equation and the second approximate curve equation, the terminal voltage and the discharge current of the battery that are periodically measured are updated for the latest predetermined time. A vehicle battery pure resistance measuring method characterized by collecting, storing and storing minute amounts.

According to the above-described procedure, when obtaining the first approximate curve equation and the second approximate curve equation, the terminal voltage and the discharge current of the battery that are periodically measured are updated. Since the data is collected, stored and stored for a predetermined time, it is confirmed that the discharge current necessary for obtaining the first approximate curve equation and the second approximate curve equation has flowed using the stored actual data. After that, the first approximate curve equation and the second approximate curve equation can be obtained using the stored actual data.

A fourth aspect of the present invention has been made to solve the above problems.
As shown in the basic configuration diagram of FIG. 1, the described invention is a vehicle battery pure resistance measuring device that measures the pure resistance of a battery mounted on a vehicle to supply power to the vehicle load. Voltage / current measuring means 23a-1 for periodically measuring a terminal voltage and a discharge current of the battery when a discharge current monotonically increases beyond the threshold value and monotonically decreases from a maximum value to a predetermined value or less; A first approximation curve expression of the voltage-current characteristic for the increasing discharge current and a second approximation of the voltage-current characteristic for the decreasing discharge current, showing a correlation between the terminal voltage measured by the current measuring means and the discharge current. Approximate curve expression calculating means 23 for obtaining a curve expression
a-2 and the two approximate quadratic curve equations obtained by the approximate curve equation calculating means, respectively, to differentiate the change in the combined resistance exhibited by the battery with respect to the increasing discharge current and the decreasing discharge current. Calculating means 23a-3 for obtaining two linear expressions shown, calculating two values corresponding to the maximum values of the obtained two linear expressions, and the battery value between the two values obtained by the arithmetic means. The present invention resides in a vehicle battery pure resistance measuring apparatus characterized in that the pure resistance is measured assuming that there is a pure resistance in the combined resistance.

According to the above configuration, a discharge current flows by supplying power from the battery to the load of the vehicle and monotonically increasing the load beyond a predetermined value and monotonically decreasing from the maximum value to a predetermined value or less. The voltage / current measuring means 23a-1 periodically measures the terminal voltage of the battery and the discharge current when the battery is discharged. The voltage for the increasing discharge current, which indicates the correlation between the terminal voltage measured by the voltage / current measuring means and the discharge current,
The approximate curve equation calculating means 23a-2 calculates a first approximate curve equation of the current characteristic and a second approximate curve equation of the voltage-current characteristic with respect to the decreasing discharge current.

In measuring the pure resistance of the battery, the calculating means 23a-3 first differentiates the two approximate quadratic curve equations obtained by the approximate curve equation calculating means, respectively, to calculate the increasing discharge current and the decreasing Two linear equations showing the change in the combined resistance exhibited by the battery with respect to the discharge current to be applied are obtained. Next, two values corresponding to the maximum values of the obtained two linear discharge currents are obtained. Then, the pure resistance is measured by multiplying the value obtained by adding the two calculated values by １ ／. The resistance value measured in this way agrees well with the resistance actually measured by another method, which means that the slope of the voltage-current characteristic due to only the resistance actually measured by the other method is different from the one at the point of the maximum value. Can be understood from the fact that the slope of the tangent at the maximum value of the voltage-current characteristic with respect to the increasing discharge current is smaller than the slope of the tangent at the maximum value of the voltage-current characteristic with respect to the decreasing discharge current.
Therefore, the terminal voltage and the discharge current of the battery when power is supplied to the load in the normal use state of the vehicle are measured,
The pure resistance of the battery can be measured simply by processing the data obtained as a result of this measurement.

According to a fifth aspect of the present invention, in the vehicle battery pure resistance measuring device according to the fourth aspect, a value at an intermediate point between the two values is measured as the pure resistance. In the resistance measuring device.

According to the above-described structure of the fifth aspect, 2
Since the value at the midpoint between the two values is measured as the pure resistance, for example, the pure resistance can be measured by a simple operation of multiplying the value obtained by adding the two values to 乗.

According to a sixth aspect of the present invention, in the apparatus for measuring the battery pure resistance of the vehicle according to the fourth or fifth aspect, the approximate curve equation calculating means includes the first approximate curve equation and the second approximate curve equation. Storage means 23b for collecting, storing, and storing terminal voltage and discharge current of the battery periodically measured by the voltage / current measurement means for a predetermined period of time in order to obtain In vehicle battery resistance measuring device.

According to the configuration of the sixth aspect, the storage means 23b determines the first approximated curve equation and the second approximated curve equation by using the battery periodically measured by the voltage / current measuring means. Are collected, stored and stored for the latest predetermined time, and a first approximate curve equation and a second approximate curve equation are obtained using the stored actual data. After confirming that the necessary discharge current has flowed, the first approximate curve equation and the second approximate curve equation can be obtained using the stored actual data.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for measuring a vehicle battery pure resistance according to the present invention will be described with reference to the drawings together with a vehicle battery pure resistance measuring apparatus according to the present invention. To consider.

By the way, 12V car, 42V car, EV car, H
EV vehicles are equipped with loads requiring a large current, such as a starter motor, a motor generator, and a driving motor.
Examples of the current (VI) characteristics are as shown in FIGS.

Conventionally, the VI characteristic is 1 as shown in FIG.
Although a method of approximating by the following equation V = aI + b has been generally used, it is difficult to obtain an equation having a high correlation with the linear equation due to the influence of the nonlinear characteristic of the polarization resistance component shown in FIG. all right. Therefore, in the present invention, as shown in FIG. 4, an approximation formula having a high correlation is used by obtaining a quadratic approximation curve expression of V = aI ² + bI + c by the least square method.

When a load requiring a large current as described above is driven, a discharge current that monotonically increases beyond a predetermined value and monotonically decreases from a maximum value of 100 A to a predetermined value or less flows by one discharge. At this time, the terminal voltage and the discharge current of the battery are periodically measured, and the discharge is started and increased as shown in the graph of FIG. 6 based on the actual data indicating the correlation between the terminal voltage and the discharge current. First approximation curve expression M1 of VI characteristic for increasing discharge current in the direction
Then, two equations of the second approximate curve equation M2 of the VI characteristic with respect to the discharge current that reaches the maximum and then decreases in the decreasing direction are obtained. The equation shown in FIG. 6 is an example of a specific approximate curve equation obtained from actual data.
The difference between these two approximate curve expressions M1 and M2 will be analyzed below.

On the other hand, in the case of the approximate curve formula M1, when the discharge starts and the current increases, the polarization resistance component gradually increases based on the polarization resistance component at the time of starting the discharge. Thereafter, when the current reaches the maximum value, the polarization resistance component reaches a peak, and the polarization should be eliminated as the current decreases. However, in practice, the polarization resistance component does not disappear in proportion to the decrease in the current, but the reaction appears later rather than disappearing. Therefore, in the case of the approximate curve equation M2, the same VI characteristic as the increasing direction is not exhibited. A larger voltage drop is generated, and two quadratic approximate curve expressions M1 and M2 corresponding to the increase and decrease of the current are obtained.

A method of measuring the pure resistance R of the battery using the above-mentioned two quadratic approximate curves M1 and M2 of the VI characteristic will be described in detail with reference to FIGS. explain.

According to the two approximate curves represented by the two quadratic approximate curves M1 and M2, the terminal voltage value for an arbitrary discharge current value is the value of the combined resistance of the battery at that current value. Is determined by Further, the change ΔV of the terminal voltage per unit change ΔI of the discharge current at an arbitrary point on the approximate curve depends on the rate of change of the approximate curve expressions M1 and M2 at that point, that is, the value of the combined resistance of the battery at that point. Determined and approximate curve expression M1
And the slope of the tangent to M2. In general, a tangent to an arbitrary point of a quadratic curve is represented by a linear expression obtained by differentiating a quadratic curve expression representing the curve, and a slope of the tangent is a combination of arbitrary points substituted into the obtained linear expression. The value reflects the value of the resistance.

More specifically, the combined resistance R of the battery is composed of a pure resistance component that keeps a constant value at all times and a polarization resistance component that changes according to the magnitude of the discharge current and the discharge time. Although it is a part of the element that determines the slope of the tangent, it does not work as the element that changes the slope of the tangent, and the slope of the tangent is changed only by the change in polarization (voltage drop) per unit current change, That is, it is a polarization resistance component. By the way, the value of the combined resistance corresponding to the current value at an arbitrary point of the battery is obtained by differentiating the two quadratic approximated curve expressions M1 and M2 (ΔV1 / ΔI, ΔV2 / ΔI).
By substituting the current value at an arbitrary point into the two primary linear equations obtained in this way, two values can be obtained. That is, since the change in polarization due to the increasing discharge current is different from the change in polarization due to the decreasing discharge current, the battery exhibits different combined resistance values when the current increases and when the discharge decreases.

More specifically, approximate curve expressions M1 and M2
The ^{respective, V1 = a1I 2 + b1I +} c1 and V2
= A2I ² + b2I + c2, these approximate curve expressions M1 and M2 are differentiated to obtain ΔV1 / ΔI = 2a1I + b
1 = R1 and ΔV2 / ΔI = 2a2I + b2 = R2. As described above, the combined resistances R1 and R2 at any point are obtained by substituting the current value at any point into the obtained linear equation.

Two specific approximate curve expressions M1 = 0.00003I ² described in FIG. 6 obtained based on actual data.
−0.0197I + 12.03243 and M2 = 0.0
In the case of 0004I ² −0.01830I + 1.772026, M1 ′ = 0.0
0006I-0.01979 = R1 (I) and M2 '=
Two first-order expressions are obtained, that is, 0.00008I-0.018301 = R2 (I). If two current-resistance characteristic lines representing the resistance that changes with respect to this current are represented by a graph,
As shown in FIG. The two straight lines shown in FIG. 7 show the change in the combined resistance of the battery with respect to the current,
Since the pure resistance component in the combined resistance always keeps a constant value with respect to the current, all the changes in the combined resistance are the polarization resistance components in the combined resistance with respect to the change in the unit current, that is, the polarization per unit current change. It can be understood that this is due to the amount of change in (voltage drop).

Further examination with reference to two quadratic approximation curves M1 and M2 and two linear equations obtained by differentiating them, the discharge current of the intersection between the approximation curves represented by the equations M1 and M2 is obtained. The point at the maximum value Ip (= 100A) is a singular point. Although the actual data at this point has the same value, the slope of the tangent at this point, ie, the primary term I in the two linear equations R1 (I) and R2 (I), is 10
Two values R1 (100) and R1 obtained by substituting 0 (A)
2 (100) is different. This is due to the fact that one is based on the approximate curve equation at the time of discharge when the current increases, and the other is based on the approximate curve equation at the time of discharge where the current decreases. Thus, two tangents having different inclinations are obtained as shown in FIG. All of the causes of this difference are the result of the discharge current switching from an increase to a decrease at a singular point, resulting in a change in the way of changing the polarization. It is imagined that the value of the pure resistance exists. This means
This is consistent with the experience that the slope of the voltage-current characteristic due to the pure resistance actually measured for various types of batteries indicates a value between the two slopes of the tangent lines at the singular points obtained for the two approximate curves.

Further analysis of the relationship between the point R of the pure resistance and the change in the combined resistance shown in the graph of FIG. 7 shows that the first approximate curve expression M of the VI characteristic with respect to the increasing discharge current is obtained.
The linear equation M1 'obtained by differentiating 1 indicates that as the discharge current increases toward the maximum value, the amount of change in polarization (voltage drop) per unit current increase gradually decreases, and the voltage per unit current change As the polarization resistance component that determines the change gradually decreases, the combined resistance gradually decreases. However, even after reaching the singular point, the operation in the battery to increase the polarization and increase the voltage drop does not stop, so the apparent combined resistance value at the singular point is greater than the pure resistance value. It is a big source. Therefore, the value at the maximum value of the linear expression M1 'obtained by differentiating the first approximate curve expression M1 of the VI characteristic with respect to the increasing discharge current, that is, the value of the combined resistance is a value larger than the value of the pure resistance. It becomes.

The operation in the battery for increasing the polarization and increasing the voltage drop as described above continues for a while even if the discharge current is switched to the decrease. For this reason, even if the discharge current decreases and the voltage drop due to the pure resistance decreases, there is an increase in the voltage drop due to the polarization, so that apparently only a smaller voltage change occurs than the voltage increase due to the pure resistance alone. As the combined resistance, the resistance is smaller than the pure resistance. However, when the discharge current continues to decrease and reaches a certain current value, the polarization stops increasing and starts to decrease.When the voltage drop due to the polarization does not change, the value of the combined resistance, that is, the slope of the tangent, Is equal to the value of pure resistance only.

After the discharge current further decreases and drops below a certain value, the speed of the polarization elimination gradually increases, and the voltage change with respect to the decrease in the current becomes larger than that of the pure resistance. The resistance value increases as the current decreases.

As is apparent from the above, the slope of the tangent line of the VI characteristic with respect to the increasing discharge current at the point of the maximum value of the discharge current, which is a singular point, is larger than the slope of the pure resistance alone and decreases. The slope of the tangent to the VI characteristic with respect to the discharge current is smaller than the slope of the pure resistance alone. This indicates that the pure resistance of the battery exists between two values indicating the magnitude of the slope at the singular point. Therefore,
The pure resistance can be measured as a value existing between the two values obtained by substituting the maximum value of the discharge current into two linear expressions obtained by differentiating the two quadratic approximation curve expressions M1 and M2. it can. Specifically, the value of the intermediate point between the two values R1 and R2 is obtained by adding the values R1 (Ip) and R2 (Ip) of the two points and dividing by 2 to obtain a pure resistance R. .

The method of measuring the vehicle battery pure resistance will be described first with reference to FIGS. When a load that requires a large current, such as a starter motor, a motor generator, or a traction motor, mounted on the vehicle to supply power to the vehicle load is operated, the battery exceeds a predetermined value and monotonically increases. Then, a discharge current that monotonously decreases from the maximum value to a predetermined value or less flows. At this time, the battery terminal voltage and the discharge current are sampled at a cycle of, for example, 1 ms, and are periodically measured, whereby a large number of sets of the battery terminal voltage and the discharge current are obtained.

The latest set of the battery terminal voltage and the discharge current obtained in this way is stored for a predetermined period of time, for example, in a memory such as a RAM as rewritable storage means, and is collected. . Using the set of the terminal voltage and the discharge current stored and stored in the memory, and using the least squares method, for example, V1 (I) of the voltage-current characteristic with respect to the increasing discharge current indicating the correlation between the terminal voltage and the discharge current ) = A1I
A first approximation curve equation M1 represented by a quadratic expression that ² + b1 + c1, voltage for decreasing the discharge current - for example, V2 of the current characteristic ^{(I) = a2I 2 + b2I} + c2 becomes the second approximation expressed by a quadratic equation A curve equation M2 is obtained.

Next, a tangent at an arbitrary point on the voltage-current characteristic curve represented by the first approximate curve equation M1 and an arbitrary point on the voltage-current characteristic curve represented by the second approximate curve equation M2 is determined. Therefore, the first approximation curve equation M1 and the second approximation curve equation M2 are respectively differentiated to obtain a first-order linear equation M1 '.
And M2 '. By substituting the current value at an arbitrary point into this linear equation, the slope of the tangent of the approximate curve equation at the arbitrary point, that is, the first approximate curve equation M1 and the second approximate curve equation M2, is used. It is possible to obtain the combined resistance of the battery at an arbitrary point on the obtained voltage-current characteristic curve. In particular, the first approximate curve expression M1 and the second approximate curve expression M2 are used to determine the slope of the tangent to the point of the maximum value of the discharge current on the two voltage-current characteristic curves.
Are substituted for the primary linear expressions M1 '= R1 and M2' = R2, respectively, obtained by differentiating. Then, the intermediate value between the slopes of the two tangents is calculated by adding the slopes of the two tangents at the maximum values of the two approximate curve expressions M1 and M2 obtained as described above and dividing the sum by two. , Can be measured as the pure resistance R in the combined resistance of the battery that does not change with current.

A specific embodiment of an apparatus for performing the above-described method for measuring a battery pure resistance of a vehicle which enables the above-described operation will be described below with reference to the drawings.

FIG. 2 is an explanatory diagram showing, in partial blocks, a schematic configuration of a vehicle battery pure resistance measuring apparatus according to an embodiment of the present invention to which the vehicle battery pure resistance measuring method of the present invention is applied. The vehicle battery pure resistance measurement device according to the present embodiment, which is indicated by the reference numeral 1, is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3.

In this hybrid vehicle, normally, only the output of the engine 3 is transmitted from the drive shaft 7 to the wheels 11 via the differential case 9 to run the vehicle. The motor 5 is configured to function as a motor, and the output of the motor generator 5 is transmitted from the drive shaft 7 to the wheels 11 in addition to the output of the engine 3 to perform the assist traveling.

The hybrid vehicle is configured such that the motor generator 5 functions as a generator (generator) at the time of deceleration or braking, and converts the kinetic energy into electric energy to charge the battery 13.

The motor generator 5 is further used as a cell motor for forcibly rotating the flywheel of the engine 3 when the engine 3 is started by turning on a starter switch (not shown). A large current flows in a short time.
When the engine 3 is started by the motor generator 5 by turning on the starter switch, the starter switch is turned off and the ignition switch and the accessory switch are turned on with the release of the operation of an ignition key (not shown). And the battery 13
The discharge current flowing from the battery shifts to a steady current.

Returning to the description of the configuration, the vehicle battery pure resistance measuring apparatus 1 of the present embodiment comprises a motor generator 5 functioning as a motor for assisting traveling or a cell motor.
A current sensor 15 for detecting a discharge current I of the battery 13 with respect to electric components and a charging current of the motor generator 5 functioning as a generator with respect to the battery 13.
And a voltage sensor 17 having an infinite resistance connected in parallel with the battery 13 and detecting a terminal voltage V of the battery 13.

Further, in the vehicle battery pure resistance measuring apparatus 1 of the present embodiment, the output of the current sensor 15 and the voltage sensor 17 is A / A in the interface circuit (hereinafter abbreviated as “I / F”) 21. It further includes a microcomputer (hereinafter abbreviated as “microcomputer”) 23 taken in after the D conversion.

The microcomputer 23 has a CPU 23
a, a RAM 23b, and a ROM 23c,
The CPU 23a includes a RAM 23b and a ROM
23c, the I / F 21 is connected.
Starter switch, ignition switch, accessory switch, and motor generator 5 (not shown)
Switches and the like of other electrical components (loads) are further connected.

The RAM 23b has a data area for storing various data and a work area used for various processing operations. The ROM 23c stores a control program for causing the CPU 23a to perform various processing operations. .

The current value and the voltage value output from the current sensor 15 and the voltage sensor 17 are sampled at high speed in a short cycle, and are taken in by the CPU 23a of the microcomputer 23 via the I / F 21 and taken in. The current value and the voltage value are stored and stored in a data area (corresponding to a storage means) of the RAM 23b from a value before a predetermined period to a latest value. The stored actual data is used to obtain a second-order approximate curve equation of the voltage-current characteristics of the battery.

Next, the processing performed by the CPU 23a in accordance with the control program stored in the ROM 23c will be described with reference to FIG.

When the microcomputer 23 is started by receiving power supply from the battery 13 and the program is started, the CPU 23
First, a performs initial setting (step S1).

When the initial setting of step S1 is completed,
Next, the CPU 23a pairs the A / D conversion value between the discharge current I of the battery 13 detected by the current sensor 15 and the terminal voltage V of the battery 13 detected by the voltage sensor 17,
A real data collection process is performed in which the latest real data read through F21 is stored in the data area of the RAM 23b for a predetermined time, stored, and collected (step S2). The actual data collection process in step S2 is always performed continuously.

Subsequently, the actual data of the latest predetermined time between the discharge current I and the terminal voltage V collected in step S2 is analyzed, and the least-squares method is applied to obtain a second-order approximation of the voltage-current characteristic. It is determined whether it is appropriate to determine the curve equation. That is, an analysis process is performed to analyze whether a discharge current that monotonically increases from the battery beyond a predetermined value and monotonically decreases from the maximum value to a predetermined value or less flows (step S3).

As a result of the analysis in step S3, the voltage-
When appropriate one for obtaining a second-order approximation curve equation of current characteristics are collected (Y of step S4), and a voltage for increasing the discharge current - current characteristic V1 (I) = a1I ²
+ B1 + C1 a first approximate curve expression M represented by a quadratic expression
1, the voltage for decreasing the discharge current - for example, V2 of the current characteristic ^{(I) = a2I 2 + b2I} + C2 becomes finding a second approximation curve equation M2 represented by the quadratic equation to perform an approximate curve equation calculation process (step S5).

After the two approximate curve equations M1 and M2 are obtained by the approximate curve equation calculation processing in step S5, next, an arithmetic processing for obtaining the pure resistance of the battery is executed (step S6). In the calculation processing in step S6, V1 of the voltage-current characteristic with respect to the increasing discharge current
(I) = the first approximation curve equation M1 represented by a1I ² + b1 + c1 becomes quadratic, voltage for decreasing the discharge current - current characteristic example ^{V2 (I) = a2I 2 +} b2I + c
A second linear equation is obtained by differentiating the second approximate curve equation M2 expressed by two quadratic equations.

In the calculation processing in step S6, the maximum value is further substituted near the two primary linear equations thus obtained, and the slopes of the two tangents at the maximum value are obtained. Then, the slopes of the two tangents determined in step S6 are averaged, and this value is measured as the pure resistance of the battery. The measured pure resistance is used for various purposes.
Is stored in the data area (step S
7). After the measurement processing in step S7 is completed, the determination in step S4 becomes Y, and the collection processing and step S2 in step S2 are performed until there is an opportunity to execute the approximate curve expression calculation processing in step S5 and the calculation processing in step S6. The analysis processing of S3 is repeatedly executed.

Further, in the vehicle battery pure resistance measuring apparatus 1 of the present embodiment, step S2 in the flowchart is a process for the voltage / current measuring means in the claims, and step S5 is an approximate curve calculating means in the claims. And step S6 is a process corresponding to the calculating means in the claims.

Next, the operation (action) of the vehicle battery resistance measuring apparatus 1 of the present embodiment configured as described above will be described.

First, in a state where electric components (loads) other than the motor generator 5 of the hybrid vehicle are operating or the motor generator 5 is operating so as to function as a motor and the battery 13 is discharging accordingly. The terminal voltage and the discharge current of the battery are periodically measured when a discharge current that monotonically increases beyond the predetermined value and monotonically decreases from the maximum value to a predetermined value or less flows to the load.

In the vehicle battery pure resistance measuring apparatus 1 of this embodiment, the latest one periodically measured is stored and stored in the data area of the RAM 23b for a predetermined time, and collected. The actual data of the latest predetermined time between the discharge current I and the terminal voltage V is analyzed, and is it suitable for obtaining a quadratic approximate curve expression of the voltage-current characteristic by applying the least squares method? Is determined. That is,
An analysis is made as to whether a discharge current that monotonically increases from a battery beyond a predetermined value and monotonically decreases from a maximum value to a predetermined value or less flows.

For this reason, the approximate curve expression calculation process is not performed until an appropriate one for obtaining the secondary approximate curve expression of the voltage-current characteristic is collected. The processing need not be performed in synchronization with the periodic measurement of the terminal voltage and the discharge current, and a high processing speed is not required.

[0066]

As described above, according to the first or fourth aspect of the present invention, the terminal voltage and the discharge current of the battery when the power is supplied to the load in the normal use state of the vehicle are measured. The data obtained as a result of this measurement is processed to obtain a first approximation curve expression of the voltage-current characteristic for the increasing discharge current and a second approximation curve expression of the voltage-current characteristic for the decreasing discharge current. Since the pure resistance is measured assuming that there is a pure resistance in the combined resistance exhibited by the battery between the two values corresponding to the maximum values of the two linear formulas, when the battery is used in a normal state, Further, it is possible to provide a method and an apparatus for measuring a battery pure resistance for a vehicle, which can measure the pure resistance of the battery even when the vehicle is in use.

According to the second or fifth aspect of the present invention, at least one of the methods for obtaining the slope between the two points for measuring the pure resistance is based on the actual data. Since it is not necessary to use the method, it is possible to provide a method and an apparatus for measuring a battery pure resistance for a vehicle, which can keep the measurement precision of the pure resistance stable.

According to the third or sixth aspect of the present invention, the discharge current necessary for obtaining the first approximate curve expression and the second approximate curve expression flows using the stored actual data. Is confirmed, and the first using the stored real data
And the second approximation curve expression can be obtained, so that a waste battery process can be omitted and the pure resistance measurement method for a vehicle battery can measure the pure resistance without performing real-time high-speed processing. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a vehicle battery pure resistance measuring device of the present invention.

FIG. 2 is an explanatory diagram showing, in partial blocks, a schematic configuration of a vehicle battery pure resistance measuring apparatus according to an embodiment of the present invention to which the vehicle battery pure resistance measuring method of the present invention is applied.

FIG. 3 is a graph showing an example of a VI characteristic represented by a first-order approximation formula.

FIG. 4 is a graph showing an example of a VI characteristic represented by a second-order approximation formula.

FIG. 5 is a graph showing an example of a change in polarization with respect to a current.

FIG. 6 is a graph showing an example of an approximate characteristic curve represented by two secondary approximate curve expressions obtained by one discharge.

FIG. 7 is a graph showing the inclination of a tangent at an arbitrary point on the two approximate characteristic curves shown in FIG.

FIG. 8 is a graph in which tangent lines are drawn at points where the discharge current on the curves has the maximum value with respect to the two approximate characteristic curves in FIG. 6;

9 is a flowchart showing processing performed by the microcomputer in FIG. 2 according to a predetermined program for measuring pure resistance.

FIG. 10 is a graph for explaining a method of measuring a pure resistance of a conventional battery.

[Explanation of symbols]

 23a-1 Voltage / current measurement means (CPU) 23a-2 Approximate curve expression calculation means (CPU) 23a-3 Calculation means (CPU) 23b Storage means (RAM)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02J 7/10 H02J 7/10 BH (72) Inventor Tomohito Enomoto 1500 Onjuku 1500, Susono City, Shizuoka Prefecture In-house (72) Inventor Tomohiro Kawaguchi 1500 Onjuku, Susono-shi, Shizuoka Prefecture F-term (reference) 2G016 CA03 CB01 CB06 CB12 CB21 CC01 CC02 CC03 CC16 CC24 CC27 CC28 5G003 BA01 CA01 CA11 CC02 DA06 EA08 FA06 GB06 GC05 5H030A AS08 FF42 FF44 FF52 5H115 PA08 PG04 PI16 PO02 PU01 PU21 QE12 SE06 TI02 TI05 TI06 TI10 TR19 TU16 TU17

Claims (6)

[Claims] 1. A vehicle battery pure resistance measuring method for measuring the pure resistance of a battery mounted on a vehicle for supplying power to a load of the vehicle, wherein the load monotonically increases beyond a predetermined value and increases from a maximum value to a predetermined value. A voltage-current characteristic for the increasing discharge current, which periodically measures the terminal voltage and the discharge current of the battery when a discharge current that monotonously decreases below the value flows and indicates a correlation between the terminal voltage and the discharge current. And a second approximate quadratic curve equation of the voltage-current characteristic with respect to the decreasing discharge current, and differentiating the two approximate quadratic curve equations, Two linear equations showing the change in the combined resistance exhibited by the battery with respect to the increasing discharge current and the decreasing discharge current are obtained, and between two values corresponding to the maximum value of the obtained two linear equations. Vehicle battery pure resistance measuring method and measuring the net resistance as there is a pure resistance in the combined resistance presented by the serial battery. 2. The vehicle battery pure resistance measuring method according to claim 1, wherein a value of an intermediate point between the two values is measured as the pure resistance. 3. The method of measuring a battery pure resistance for a vehicle according to claim 1, wherein the first approximate curve equation and the second approximate curve equation are periodically measured when obtaining the first approximate curve equation and the second approximate curve equation. A method for measuring a battery pure resistance for a vehicle, wherein a voltage and a discharge current are collected, stored, and stored for the latest predetermined time. 4. A vehicle battery pure resistance measuring device for measuring a pure resistance of a battery mounted on a vehicle to supply power to a load of the vehicle, wherein the load monotonically increases beyond a predetermined value and increases from a maximum value to a predetermined value. A voltage / current measuring means for periodically measuring a terminal voltage and a discharging current of the battery when a discharging current monotonously decreasing below the value flows; and a terminal voltage and a discharging current measured by the voltage / current measuring means. Approximation curve expression calculating means for obtaining a first approximation curve expression of a voltage-current characteristic with respect to the increasing discharge current and a second approximation curve expression of the voltage-current characteristic with respect to the decreasing discharge current. The two approximate quadratic curve equations obtained by the approximate curve equation calculation means are respectively differentiated to calculate the combined resistance of the battery with respect to the increasing discharge current and the decreasing discharge current. Calculating means for obtaining two linear expressions indicating the change, and obtaining two values corresponding to the maximum values of the obtained two linear expressions; and presenting the battery between the two values obtained by the arithmetic means. A battery pure resistance measuring device for a vehicle, wherein the pure resistance is measured assuming that there is a pure resistance in the combined resistance. 5. The vehicle battery pure resistance measuring device according to claim 4, wherein a value of an intermediate point between the two values is measured as the pure resistance. 6. The vehicle battery pure resistance measuring device according to claim 4, wherein the approximate curve equation calculating means is configured to determine the first approximate curve equation and the second approximate curve equation. A battery pure resistance measuring device for a vehicle, comprising storage means for collecting, storing, and storing terminal voltage and discharge current of the battery periodically measured by a voltage / current measuring means for a latest predetermined time. .