JP2003115331A - Measurement method and device of pure resistance of on board battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement method and device of pure resistance of on board battery wherein the pure resistance of the battery can be measured even if the vehicle is in use. SOLUTION: During the period in which monotonously decreasing rush current to flow after monotonously increase from 0 to the peak value in a constant load prescribed beforehand among loads of the vehicle, discharging current of the battery and this terminal voltage corresponding to this discharging current are periodically measured by a current/voltage measurement means 23a-1. The first approximation equation of current-voltage characteristic against increasing discharging current and the second approximation equation of current-voltage characteristic against decreasing discharging current are calculated by an approximation equation calculating means 23a-2. In case voltage reduction by concentration polarization component is included, an intermediate value of two terminal voltage change values per unit current change at the point corresponding to the peak value of the first and the second approximation equations excluding this voltage reduction is calculated by a calculating means 23a-3, and the measurement is made as the pure resistance value of the battery.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, a battery can be repeatedly used within the range of its charge capacity by charging it so as to cover the discharge current, but it has caused an unexpected situation such as over-discharge and lack of electrolyte. Of course, even if these situations are not brought about, if the battery is used for a long period of time and aged, the dischargeable capacity, which is the amount of electric power that can be supplied to the load by discharge, will suddenly decrease. Therefore, in the state where the dischargeable capacity has decreased due to aging, even if a discharge exceeding the charge occurs for a short period of time, it may not be possible to start the starter motor and restart the engine after the engine is stopped. Absent.

Incidentally, when comparing a new battery with an aged battery, it is known that the battery with an aged battery has a larger net resistance than the new battery. Therefore, it has been considered to measure the pure resistance of the battery as a guide for battery replacement, for example, at the time of periodic inspection of the vehicle. This is because by knowing the pure 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.

Generally, when a current is discharged from a battery, the terminal voltage of the battery drops. The voltage drop is due to the internal impedance (composite resistance) of the battery, but IR loss (pure resistance, that is, voltage drop due to ohmic resistance) due to the structure of the battery and polarization resistance due to chemical reaction. It can be divided into voltage drops due to components (activation polarization, concentration polarization). When the current-voltage (IV) characteristic is obtained, as shown in FIG.
The voltage drop due to IR loss does not change if the battery state is the same, but the voltage drop due to the polarization resistance component changes depending on the magnitude of the current and the time during which the current is discharged. It is known that when various states of the battery are estimated from the IV characteristics including such a polarization resistance component, an inaccurate estimation result is obtained. Therefore, a technique for measuring only the pure resistance obtained by separating the polarization resistance component is required.

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 voltage drop such as polarization occurs in the electrolyte. The net resistance of the battery is being measured when it is in the unbalanced state.

As an example thereof, the battery has a frequency of 1 kHz to 1 kHz.
A method of obtaining a pure resistance from the relationship between a voltage and a current that changes within a fixed time of, for example, about 1 μsec in a situation in which charging / discharging is repeated by applying an alternating current with a frequency of about 00 kHz and neither polarization of charging nor discharging is accumulated. There is. This is because, as shown in FIG. 13, after the discharge is stopped, the voltage recovers sharply and then gradually recovers.
It is considered that the rapid voltage recovery within t is caused only by the component due to the pure resistance R, and the gradual change thereafter is caused by the components (capacitance and inductance components) other than the pure resistance including polarization, and 1 kHz.
It is intended to measure the pure resistance by catching the change of voltage and current within a short time of each application cycle of alternating current having a frequency of about 100 kHz.

[0007]

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

Further, in the case of the above-mentioned example, since it is necessary to collect the data of the voltage V and the current I within a short time, it is necessary to perform sampling with a very short cycle and perform A / D conversion within a certain time Δt. Although it has to be carried out and can be realized as a measuring instrument used alone, it is very difficult to mount it on a vehicle and use it. Moreover, in order for the obtained ΔV / ΔI to be accurate, each of ΔV and ΔI must show a large value, but such a thing can be measured only when the vehicle is limited. Furthermore, any alternating current cannot be applied to the battery during vehicle operation. Therefore, there is the reality that the method described above cannot be applied to measure the net resistance of a battery during vehicle use.

Therefore, in view of the above situation, it is an object of the present invention to provide an on-vehicle battery pure resistance measuring method and device capable of measuring the pure resistance of a battery even during use of the vehicle.

[0010]

In order to achieve the above object, the present invention according to any one of claims 1 to 12 relates to a method for measuring the on-vehicle battery pure resistance, and the invention according to claim 13 relates to the on-vehicle battery pure resistance measurement. It relates to the device.

Claim 1 which was made in order to solve the above-mentioned topic
The described invention is an in-vehicle battery pure resistance measuring method for measuring a pure resistance of a battery mounted in a vehicle for supplying electric power to a load of the vehicle, wherein a predetermined constant load among the loads is from 0 to a peak value. After the monotonous increase, during the period when the inrush current flows, which monotonically decreases from the peak value to the steady value,
A first approximation of a current-voltage characteristic with respect to the increasing discharge current, which periodically measures a discharge current of the battery and a terminal voltage corresponding to the discharge current and shows a correlation between the measured discharge current and the terminal voltage. And a second approximation formula of the current-voltage characteristic with respect to the decreasing discharge current, and when the first and second approximation formulas include a voltage drop due to a concentration polarization component, the first and second approximation formulas exclude the voltage drop. The intermediate value of the two terminal voltage change values per unit current change at the point corresponding to the peak value of the first and second approximate expressions is obtained, and the obtained intermediate value is measured as the pure resistance value of the battery. The present invention resides in a method of measuring a vehicle battery pure resistance.

According to the above-mentioned procedure of claim 1, an inrush current that monotonically increases from 0 to a peak value and then monotonically decreases from a peak value to a steady value flows to a predetermined constant load of the vehicle load. The discharge current of the battery and the terminal voltage corresponding to the discharge current are periodically measured during the charging period, and the first approximation of the current-voltage characteristic with respect to the increasing discharge current showing the correlation between the discharge current and the terminal voltage. A formula and a second approximation formula of the current-voltage characteristic with respect to the decreasing discharge current are obtained.

Next, when the voltage drop due to the concentration polarization component is included in the first and second approximation formulas, this voltage drop is removed from the first and second approximation formulas, and the approximation formula of pure resistance and activation polarization only. Then, paying attention to the peak value that is common to the increasing and decreasing directions, two terminals per unit current change at the points corresponding to the peak values of both approximate expressions excluding the voltage drop due to the concentration polarization component. An intermediate value of the voltage change values is obtained, and the obtained intermediate value is measured as the value of the pure resistance of the battery. Therefore, by measuring the discharge current and terminal voltage of the battery when power is supplied to the load under the normal use condition of the vehicle and processing the data obtained as a result of this measurement, it is possible to measure the pure resistance of the battery. You can

According to a second aspect of the present invention, in the vehicle battery pure resistance measuring method according to the first aspect, the intermediate value is
A value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component is obtained by averaging. This is in the on-board battery pure resistance measuring method.

According to the above-mentioned procedure of claim 2, the intermediate value per unit current change at the point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Since the values of the changes in the two terminal voltages are calculated by averaging, when the changes in the activation polarization at the points corresponding to the peak values are equal, the peak values in the first and second approximate expressions are used. The pure resistance of the battery can be measured by adding the differential value at the point of adding and dividing by 2.

According to a third aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to the first aspect, the intermediate value is
The total of the inrush currents flowing at two terminal voltage change values per unit current change at points corresponding to the peak values of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. A vehicle-mounted battery pure resistance measuring method is characterized in that the ratios of time in the monotonous increase period and the monotonous decrease period in the time are multiplied and then obtained.

According to the procedure described in claim 3, the intermediate value per unit current change at the point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component. Since the values of the two terminal voltage changes are multiplied by the ratios of the monotonous increasing period and the monotonic decreasing period of the total time during which the inrush current flows, the values are added together. It is possible to obtain an intermediate value in consideration of the mutual influence of and, and measure it as the value of the pure resistance of the battery.

According to a fourth aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to any one of the first to third aspects, when the first and second approximate expressions are quadratic expressions, the intermediate value In obtaining the value, first and second modified approximate expressions are obtained by removing the voltage drop due to the concentration polarization component from the first and second approximate expressions, and the peak values of the first and second modified approximate expressions are obtained. 2 per unit current change at the point corresponding to
A method for measuring the on-board battery pure resistance is characterized in that the value of the change in one terminal voltage is obtained.

According to the above-mentioned procedure of claim 4, when the first and second approximate expressions are quadratic equations, the concentration polarization component is calculated from the first and second approximate expressions when obtaining the intermediate value. The first and second modified approximate expressions excluding the voltage drop due to are calculated, and the values of two terminal voltage changes per unit current change at points corresponding to the peak values of the first and second modified approximate expressions are calculated. Therefore, for example, when the modified approximate expression is a linear expression, its slope is used, and when it is a quadratic expression, the intermediate resistance is obtained by using the differential value at the peak value, whereby the pure resistance can be measured.

According to a fifth aspect of the present invention, there is provided the vehicle-mounted battery pure resistance measuring method according to the fourth aspect, wherein the first and second aspects are the same.
The difference in the terminal voltage of the battery at the point where the discharge current is 0 according to the above equation is calculated, and the total concentration polarization component generated during the period when the inrush current increases from 0 to the peak value and decreases from the peak value to 0 The voltage drop due to the concentration polarization component occurring until the inrush current occupying the total concentration polarization component reaches a peak value from 0 is obtained, and the voltage value excluding the obtained voltage drop is calculated as The in-vehicle battery pure resistance measuring method is characterized in that a quadratic equation in which a quadratic coefficient is determined by substituting the quadratic approximation equation of ## EQU1 ## into an equation in which a constant and a primary coefficient are equal is obtained as the first modified approximation .

According to the above-mentioned procedure of claim 5, the inrush current increases from 0 to the peak value to increase the peak value of the difference in the terminal voltage of the battery at the point where the discharge currents of the first and second approximate expressions are 0. It is regarded as the voltage drop due to the total concentration polarization component generated in the period from 0 to 0, and the voltage drop due to the concentration polarization component generated until the inrush current occupying in this total concentration polarization component reaches the peak value from 0 is obtained and obtained. Since the voltage value excluding the voltage drop is substituted into the first quadratic approximation formula and the formula in which the constant and the primary coefficient are equal, the quadratic coefficient is determined as the first modified approximation formula. Therefore, it is possible to accurately obtain a modified approximate expression excluding the concentration polarization component.

According to a sixth aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to the fifth aspect, in addition to the voltage value excluding the voltage drop due to the concentration polarization component in the peak value, a value between the peak value and 0 is obtained. A two-dimensional voltage value excluding the voltage drop due to the concentration polarization component is obtained, and a quadratic equation in which a coefficient is determined using the three voltage values is obtained as the second modified approximate equation. It exists in the resistance measurement method.

According to the above-mentioned procedure of claim 6, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the voltage drop due to the concentration polarization component between the peak value and 0 is excluded. Since the quadratic equation in which three voltage values are obtained and the coefficient is determined using the three voltage values is obtained as the second modified approximation equation, the second quadratic modified approximation excluding the voltage drop due to the concentration polarization component is obtained. The formula can be easily obtained.

According to a seventh aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to the sixth aspect, in order to obtain the intermediate value, a differential value at a peak value of the first and second modified approximate expressions. The present invention resides in a method for measuring a vehicle battery pure resistance, which is characterized in that

According to the above-mentioned procedure of claim 7, when both the first and second modified approximate expressions are quadratic expressions, it is only necessary to find the intermediate value of the differential value at the peak value. Pure resistance can be measured by a simple calculation.

According to an eighth aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to the fifth aspect, in addition to the voltage value excluding the voltage drop due to the concentration polarization component in the peak value, 0 point and the peak value and 0 The two voltage values excluding the voltage drop due to the concentration polarization component at the intermediate point between are calculated, and the quadratic equation in which the coefficient is determined by using the three voltage values is obtained as the second modified approximate expression. It lies in the characteristic on-board battery pure resistance measuring method.

According to the above-mentioned procedure of claim 8, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the concentration polarization component at the zero point and at the midpoint between the peak value and 0 is used. A two-dimensional equation in which the two voltage values excluding the voltage drop are obtained and the coefficient is determined using the three voltage values is obtained as a second modified approximate equation, and the zero point that originally does not include the concentration polarization component is used. Therefore, the processing for obtaining an approximate expression excluding the concentration polarization component can be reduced.

According to a ninth aspect of the present invention, in the on-vehicle battery pure resistance measuring method according to the fifth aspect, in addition to the voltage value excluding the voltage drop due to the concentration polarization component in the peak value, a value between the peak value and 0 is obtained. The voltage value excluding the voltage drop due to the concentration polarization component at the intermediate point is obtained, the linear equation determined by connecting the two points is obtained as the second modified approximate equation, and the second value is obtained in order to obtain the intermediate value. A method of measuring the on-board battery pure resistance is characterized in that the slope of the modified approximate expression is used.

According to the above-mentioned procedure of claim 9, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the voltage drop due to the concentration polarization component at the midpoint between the peak value and 0 is determined. The voltage value removed is obtained, the linear expression determined by connecting the two points is obtained as the second modified approximate expression, and the slope of the second modified approximate expression is used to obtain an intermediate value. The process for obtaining the value of becomes simple.

According to a tenth aspect of the present invention, there is provided a vehicle battery pure resistance measuring method according to any one of the fifth to ninth aspects,
The terminal voltage of the battery at the point where the voltage drop due to the concentration polarization component occurring until the inrush current in the total concentration polarization component reaches a peak value from 0 is the discharge current 0 of the first and second approximate expressions. Is calculated by multiplying the difference between the current-time product from 0 to the peak value with respect to the current-time product when the inrush current increases from 0 to the peak value and decreases from the peak value to 0. Exists in pure resistance measurement method.

According to the above-mentioned procedure of claim 10,
The voltage drop due to the concentration polarization component that occurs when the inrush current in the total concentration polarization component reaches a peak value from 0 is
And the difference in the terminal voltage of the battery at the point where the discharge current in the second approximation formula is 0, from 0 to the peak value for the current-time product when the inrush current increases from 0 to the peak value and decreases from the peak value to 0. Since it is calculated by multiplying by the ratio of the current-time product of, the voltage drop due to the concentration polarization component that occurs until the inrush current reaches the peak value from 0 is known, and the voltage corresponding to the peak value excluding the voltage drop due to the concentration polarization component The value can be calculated.

The invention described in claim 11 is the method for measuring the on-vehicle battery pure resistance according to any one of claims 5 to 9,
From the first and second approximation formulas, the difference equation between the two formulas is obtained, and the voltage drop due to the concentration polarization component generated until the inrush current occupying the total concentration polarization component reaches a peak value from 0 And the difference between the terminal voltage of the battery at the point where the discharge current is 0 in the second approximation formula, and the current value which is 0 based on the formula for the difference and the current value which is twice the peak current value. It is characterized in that it is obtained by multiplying the ratio of the difference between the voltage value at the point that is the peak current value and the voltage value at the point that is the current value twice the peak current value with respect to the difference between the voltage value at the point that is the value. It exists in the on-board battery pure resistance measurement method.

According to the above-mentioned procedure of claim 11,
From the first and second approximation formulas, the difference between the two formulas is obtained, and the voltage drop due to the concentration polarization component generated until the inrush current occupying the total concentration polarization component reaches a peak value from 0 is calculated as follows. The difference between the terminal voltage of the battery at the point where the discharge current is 0 in the approximate expression, and the voltage at the point where the current value is 0 obtained based on the expression for the difference and the voltage at the point where the current value is twice the peak current value The first and second approximations are made by multiplying by the ratio of the difference between the voltage value at the point of the peak current value and the voltage value at the point of the current value twice the peak current value with respect to the difference with the value. Even if the current-time product is not found only by knowing the equation, the voltage drop due to the concentration polarization component that occurs until the inrush current reaches the peak value from 0 is known, and the voltage corresponding to the peak value excluding the voltage drop due to the concentration polarization component. The value can be calculated.

The invention described in claim 12 is the method for measuring the on-vehicle battery pure resistance according to any one of claims 1 to 3,
In the case where the constant load is such that an inrush current that monotonically increases to a peak value flows in a short time without occurrence of concentration polarization, the first approximate expression is a linear expression, and in order to obtain the intermediate value, The vehicle-mounted battery pure resistance measuring method is characterized by using the slope of the first approximate expression.

According to the above-mentioned procedure of claim 12,
When the constant load is such that an inrush current that monotonically increases to the peak value flows in a short time without the occurrence of concentration polarization, the first approximate expression is a linear expression, and the first approximate expression is used to obtain an intermediate value. Since the slope of the approximate expression is used, not only the process for obtaining the intermediate value can be simplified, but also the approximate expression can be easily obtained.

Claim 1 which was made in order to solve the above-mentioned topic
In the invention described in No. 3, as shown in the basic configuration diagram of FIG. 1, in an in-vehicle battery pure resistance measuring device for measuring a pure resistance of a battery mounted in a vehicle for supplying electric power to a load of the vehicle, one of the loads is previously set. During a period in which an inrush current that monotonically increases from 0 to a peak value and then monotonically decreases from a peak value to a steady value is flowing in a predetermined constant load, the discharge current of the battery and a terminal voltage corresponding to the discharge current are cycled. And a first approximate expression of current-voltage characteristics with respect to the increasing discharge current showing the correlation between the discharge current measured by the current / voltage measuring means and the terminal voltage. Approximation formula calculating means 23a- for obtaining the second approximation formula of the current-voltage characteristic with respect to the decreasing discharge current
2 and a unit current change at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop when the voltage drop due to the concentration polarization component is included in the first and second approximate expressions. An in-vehicle battery, comprising: an arithmetic means 23a-3 for obtaining an intermediate value of the two terminal voltage change values per hit, and measuring the intermediate value obtained by the arithmetic means as the value of the pure resistance of the battery. Exists in pure resistance measuring device.

According to the above-mentioned structure of claim 13,
Corresponding to the discharge current of the battery and this discharge current during a period in which an inrush current that monotonically increases from 0 to a peak value and then monotonically decreases from the peak value to a steady value is flowing to a predetermined constant load of the vehicle load. The terminal voltage is periodically measured by the current / voltage measuring means 23a-1 and decreases with the first approximate expression of the current-voltage characteristic with respect to the increasing discharge current showing the correlation between the measured discharge current and the terminal voltage. The second approximate expression of the current-voltage characteristic with respect to the discharge current and the approximate expression calculating means 2
3a-2 is obtained, and when the first and second approximate expressions include a voltage drop due to the concentration polarization component, the first
And an intermediate value of the two terminal voltage change values per unit current change at the point corresponding to the peak value of the second approximation formula, and the calculating means 23a-3 calculates the calculated intermediate value. It is designed to be measured as the value of. Therefore, by measuring the discharge current and terminal voltage of the battery when power is supplied to the load under the normal use condition of the vehicle and processing the data obtained as a result of this measurement, it is possible to measure the pure resistance of the battery. You can

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing a vehicle-mounted battery pure resistance measuring device according to the present invention with reference to FIG.
The method for measuring the on-vehicle battery pure resistance according to the present invention will be described with reference to FIG.

By the way, as a vehicle load in which a battery is mounted and which is operated by being supplied with electric power from the battery, 12 V is used.
Vehicles, 42V vehicles, EV vehicles, and HEV vehicles are equipped with a constant load such as a starter motor, a motor generator, and a traveling motor that requires a large current. For example, when a starter motor or similar high-current constant load is turned on,
In the constant load, a rush current flows in the initial stage of its driving, and then a steady-state current according to the size of the load flows. Incidentally, when the load is a lamp, what corresponds to the inrush current may be called rush current.

When a DC motor is used as the starter motor, as shown in FIG. 3, the inrush current flowing from the field coil is almost zero within a short time of, for example, 3 milliseconds immediately after the start of constant load driving. After monotonically increasing to a peak value that is many times larger than the steady current, for example, 500 (A), it monotonically decreases from this peak value to a steady value according to the magnitude of the constant load within a short time of, for example, 150 milliseconds. It flows in such a manner and is supplied as discharge current from the battery. Therefore, by measuring the discharge current of the battery and the corresponding terminal voltage in the situation where the inrush current flows in the constant load, the discharge of the battery showing the change of the terminal voltage with respect to the current change in a wide range from 0 to the peak value. Current (I)-
The terminal voltage (V) characteristic can be measured.

Therefore, as a simulated discharge corresponding to the inrush current flowing when the starter motor is turned on, it increases from 0 to almost 200 A in 0.25 seconds, and decreases from the peak value to 0 in the same time. The battery is discharged using an electronic load, and the discharge current of the battery at that time and the terminal voltage are paired and measured at a short fixed period. The terminal voltage was made to correspond to each axis | shaft, and it plotted, and the graph shown in FIG. 4 was obtained. The current-voltage characteristics when the discharge current increases and decreases when shown in the graph of FIG. 4 can be approximated to the following quadratic equation using the least square method. V = a1I ² + b1I + c1 (1) V = a2I ² + b2I + c2 (2) The curves of the quadratic approximation formula are also drawn in the figure.

In FIG. 4, the voltage difference between the intercept of the approximate curve in the current increasing direction and the intercept of the approximate curve in the current decreasing direction is the voltage difference at the time of 0 (A) when the current does not flow, and therefore the pure resistance It is considered that the voltage drop is caused only by the concentration polarization component newly generated by the discharge and does not include the voltage drop caused by the activation polarization. Therefore, this voltage difference is due only to the concentration polarization, and the concentration polarization at the point of current 0 (A) is Vpolc.
Set to 0. This concentration polarization Vpolc0 is obtained by multiplying the magnitude of the inrush current by the time when the current flows, that is, A
h (since it is a short time, it will be expressed as Asec below).

Next, the concentration polarization Vpo at this current 0 (A) point
A method of calculating the concentration polarization of the current peak value using lc0 will be described. Assuming that the concentration polarization of the current peak value is Vpolcp, Vpolcp is expressed by the following equation. Vpolcp = [(Asec when current increases) / (Asec of entire discharge)] × Vpolc0 (3) The Asec of the entire discharge is expressed by the following equation. Total discharge Asec = (Asec when current increases + Asec when current decreases)

The concentration polarization Vpolcp at the peak value obtained as described above is added to the voltage at the peak value of the equation (1) to eliminate the concentration polarization component at the peak value as shown in FIG. When the voltage after removing the concentration polarization component in the peak value is V1, V1 is expressed by the following equation. ^{V1 = a1Ip 2 + b1Ip + c1} + Vpolcp Ip is a current value at the peak value.

Next, using V1 obtained as described above, a voltage drop curve of pure resistance and activation polarization as shown in FIG. V = a3I ² + b3I + c3 (4)

Focusing on the initial state of the characteristics represented by the equations (1) and (4), that is, the current is 0 (A),
Since the polarization in the initial state is the same, c3 = c1. Also,
Although the current rapidly increases from the initial state of the current increase, assuming that the reaction of concentration polarization is slow and the reaction hardly progresses, the differential of the point where the current in equations (1) and (4) is 0 (A). Since the values are equal, b3 = b1. Therefore, c3 ＝ c1
, B3 = b1 is substituted, the equation (4) is rewritten as V = a3I ² + b1I + c1 (5), and the unknown number is only a3.

Then, substituting the coordinates (Ip, V1) of the peak value of the current increase into the equation (5) and rearranging for a3,
The following formula is required. a3 = (V1-b1Ip -c1) / Ip 2 Therefore, Equation voltage drop curve of only the pure resistance and the activation polarization component (4) is determined by equation (5).

Generally, since the pure resistance is not generated by a chemical reaction, it is constant unless the state of charge (SOC), temperature, etc. of the battery is changed, so that it can be said that it is constant during one starter motor operation. . On the other hand, the activation polarization resistance is a resistance caused by a chemical reaction at the time of transfer of ions and electrons, and therefore, it may influence the concentration polarization and interact with each other. Since the current decrease curves do not completely match, it can be said that the equation (5) is a curve in the current increasing direction of the pure resistance and the activation polarization excluding the concentration polarization component.

Next, how to delete the concentration polarization component from the current decrease curve will be described below. The relational expression between the pure resistance and the current decreasing direction of the activation polarization can be obtained by the same method as the deletion of the concentration polarization at the current peak value. 2 other than peak value
The points are points A and B, and the concentration polarization Vpolc at each point
A and VpolcB are obtained by the following equation. VpolcA = [(Asec from start of current increase to point A) / (Asec of total discharge)] × Vpolc0 (6) VpolcB = [(Asec from start of current increase to point B) / (total discharge) Asec)] × Vpolc0 …… (7)

When the two points in which the concentration polarization component is deleted in addition to the peak value are obtained by the above equations (6) and (7), the following equation is used by utilizing the coordinates of these two points and the peak value. As shown in FIG. 6, the pure resistance and the current polarization direction curve of the activation polarization are obtained. V = a4I ² + b4I + c4 (8) The coefficients a4, b4, and c4 of the equation (8) are respectively substituted into the equation (8) by the two points A and B and the current value and the voltage value at the peak point. It can be determined by solving the simultaneous equations of three points set up.

Next, the method of calculating the pure resistance will be described. The pure resistance and activation polarization curves of the pure resistance and activation polarization in which the concentration polarization component is deleted, which is expressed by the above formula (5), and the pure resistance and activation polarization, which are also expressed by the formula (8) and in which the concentration polarization component is deleted The difference from the curve in the current decreasing direction is due to the difference in the activation polarization component, and therefore the pure resistance is required except for the activation polarization component.

Now, paying attention to the peak values of both curves where the activation polarizations are equal to each other, the differential value R1 of the current increase and the differential value R2 of the current decrease at the peak value are obtained by the following equations. R1 = 2 × a3 × Ip × b3 (10) R2 = 2 × a4 × Ip × b4 (11) The difference between the differential values R1 and R2 obtained by the above equation is
This is because one is the peak value in the increasing direction of the activation polarization, while the other is the peak value in the decreasing direction. Then, as a simulated discharge corresponding to the inrush current,
When an electric load is used to cause the battery to perform a discharge that increases from 0 to 200 A over 0.25 seconds and decreases over the same time from the peak value to 0, a change in both values near the peak value Since it can be understood that the rates are equal and the current-voltage characteristic due to the pure resistance exists between the two, the pure resistance R can be obtained by the following equation by adding both differential values and dividing by two. R = (R1 + R2) / 2 (12)

In the above, the case where a simulated discharge corresponding to an inrush current is made to occur in a battery using an electronic load has been described. However, in the case of an actual vehicle, a DC motor is used as the starter motor as described above. When used, the current reaches its peak while the inrush current flows through the field coil,
Cranking operates at a current that has reached a peak and has dropped below half the peak current. Therefore, the current increasing direction ends in a short time of 3 milliseconds (msec), and there is a fast current change in which the concentration polarization hardly occurs at the current increasing peak value, but the current decreasing direction is smaller than the current increasing direction. Since the current flows for a long time of 150 msec, a large concentration polarization occurs although it is in the decreasing direction.
However, in the cranking period, a phenomenon that is different from the period in which the inrush current flows occurs, so the current-voltage characteristics in the direction of current decrease are determined for the battery discharge current and terminal voltage during this period. Do not use it as data for.

In such a situation, in the actual vehicle, the current increasing direction can be approximated by a straight line connecting the current increasing start point and the peak value, as shown in FIG. The occurrence of concentration polarization at 500 (A) can be approximated to 0 (A). In this case, for the current increasing direction, the slope of the approximate straight line in the current increasing direction is used as the differential value of the peak value. However, in such a case, the slope of the approximate straight line in the current increasing direction,
It is not possible to simply add and average the slope of the tangent line at the peak point of the quadratic approximation formula in the current decreasing direction. Because in this situation, up to and after the peak,
This is because the degree of occurrence of activation polarization is completely different, and the assumption that the rates of change of the two become equal in the vicinity of the peak value cannot be established. In such a case, in obtaining the pure resistance, two terminal voltage change values per unit current change at points corresponding to the peak values of the first and second approximate expressions excluding the voltage drop due to concentration polarization, That is, the slope may be multiplied by the ratio of the time of the monotonous increase period and the time of the monotonous decrease period to the total time during which the inrush current flows, and then added. That is, the total time is proportionally proportionally divided by the time required for monotonous increase and monotonous decrease respectively, and the respective proportions are multiplied and then added. By doing so, the pure resistance can be obtained in consideration of the mutual influence of the activation polarization and the concentration polarization. That is, in principle, the activation polarization has a magnitude corresponding to the current value, but it does not occur as in principle depending on the concentration polarization amount at each time, and the smaller the concentration polarization, the smaller the activation polarization. And the bigger it is, the bigger it becomes. In any case, the intermediate value of the two terminal voltage change values per unit current change at the point corresponding to the peak value of the two approximate expressions excluding the voltage drop due to the concentration polarization component is taken as the pure resistance value of the battery. Can be measured.

In recent vehicles, the motor is
AC motors that require three-phase inputs, such as DC brushless magnet magnets, are increasingly used. In the case of such a motor, the inrush current does not reach the peak value so quickly and in a short time,
Since it takes about c time and concentration polarization occurs in the direction of increasing the current, the current change curve in the direction of increasing current needs to be quadratic-approximated as in the case of the simulated discharge described above. .

In the case of approximating the current decreasing direction of activation polarization, the peak value and the other two points are determined as shown in FIG.
As shown in, if the point of the current 0 (A) is used as the point B, the calculation for obtaining the approximate expression can be simplified.

Further, for example, when a point where concentration polarization is deleted is set at a point corresponding to a current value of about 1/2 of the peak current, as shown in FIG. 9, this point and the peak value are connected. It may be linearly approximated to a straight line. In this case, for the current decrease direction, the slope of the approximate straight line in the current decrease direction will be used as the differential value of the peak value, but an accurate pure resistance that is the same as that using the quadratic curve is obtained. Desired. In short, the intermediate value of the two terminal voltage change values per unit current change at the point corresponding to the peak value of the two approximate expressions excluding the voltage drop due to the concentration polarization component is measured as the pure resistance value of the battery. be able to.

Therefore, an in-vehicle battery pure resistance measuring method is
A specific description will be given of a case where, for example, a starter motor is used as the constant load, in which an inrush current that causes concentration polarization occurs in both the increasing discharge current and the decreasing discharge current.

When the constant load is operated, a discharge current flows from the battery, which exceeds the steady value and monotonically increases and monotonically decreases from the peak value to the steady value. The discharge current and the terminal voltage of the battery at this time are, for example, 100 microseconds (μsec).
By periodically sampling, the measurement is performed periodically, and a large number of sets of battery discharge current and terminal voltage are obtained.

The latest set of the battery discharge current and the terminal voltage thus obtained is stored for a predetermined time, for example, in a memory such as a RAM as a rewritable storage means, stored and collected. . A current-voltage characteristic with respect to an increasing discharge current and a decreasing discharge current showing a correlation between the terminal voltage and the discharge current by a least square method using a set of the discharge current and the terminal voltage stored in the memory and collected. For two, two quadratic approximation formulas as shown in formulas (1) and (2) are obtained. Next, the voltage drop due to the concentration polarization component is deleted from these two approximation formulas, and a modified quadratic approximation formula that does not include the concentration polarization component is obtained.

For this purpose, first, the voltage difference at the time of 0 (A) in which no current flows in the approximation formulas (1) and (2) is
There is no voltage drop due to pure resistance and activation polarization, and it is determined as due to concentration polarization. Further, by utilizing this voltage difference, the voltage drop due to the concentration polarization component at the current peak value in the approximate expression (1) of the current-voltage characteristic for the increasing discharge current is obtained. For this purpose, the concentration polarization utilizes the fact that it changes according to the current-time product obtained by multiplying the magnitude of the current by the time during which the current flows.

When the voltage drop due to the concentration polarization component at the current peak value on the approximate formula of the current-voltage characteristic for the increasing discharge current is obtained, then both the approximation formula not including the concentration polarization component and the approximation formula including it. Assuming that the constant and the linear coefficient are equal, a quadratic coefficient of the approximate expression not included is determined, and a quadratic approximate expression (5) obtained by modifying the approximate expression of the current-voltage characteristic for the increasing discharge current is obtained.

Next, with respect to the current-voltage characteristic with respect to the decreasing discharge current, an approximate expression not including the concentration polarization component is obtained from the approximate expression (2). For this purpose, two points in which the concentration polarization component is deleted in addition to the peak value are obtained. At this time, the concentration polarization utilizes the fact that it changes according to the current-time product obtained by multiplying the magnitude of the current by the time during which the current flows. Then, if two points are obtained in which the concentration polarization component is deleted in addition to the peak value,
Utilizing the coordinates of these three points of the two points and the peak value, a quadratic approximation formula (8) obtained by modifying the approximation formula (2) of the current-voltage characteristic for the decreasing discharge current is obtained.

The modified quadratic approximation formula for the current increasing direction of the pure resistance and the activation polarization in which the concentration polarization component represented by the above formula (5) is deleted, and the concentration polarization component represented by the formula (8) are deleted. Since the modified quadratic approximation formula of the pure resistance and the current decreasing direction of the activation polarization is due to the difference in the activation polarization component, the pure resistance can be obtained excluding the activation polarization component. For this reason, paying attention to the peak value of both approximate expressions, the difference between the differential value of the current increase and the differential value of the current decrease at the peak value is that one is in the increasing direction of the activation polarization, while the other is Although it is due to the decreasing direction, it is assumed that the current-voltage characteristic due to pure resistance exists in the middle of the rate of change of both in the vicinity of the peak value, and the total time during which the inrush current flows in both differential values The net resistance is obtained by multiplying the respective ratios of the monotonous increase period and the monotonic decrease period, and then adding them. For example,
Current increase time is 3 msec, current decrease time is 100 ms
ec, the differential value of the current increase at the peak value is Rpolk1,
When the differential value of the current decrease is Rpolk2, the pure resistance R can be calculated as follows. R = Rpolk1 × 100/103 + Rpolk2 × 3/103

A concrete embodiment of an apparatus for carrying out the above-described method for measuring the on-board battery pure resistance of the present invention by enabling the above will be described with reference to FIG. 2 again.

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

In this hybrid vehicle, only the output of the engine 3 is normally transmitted from the drive shaft 7 to the wheels 11 via the differential case 9 to drive the hybrid vehicle, and when the load is high, the electric power from the battery 13 is used to drive the motor generator. 5 is made to function as a motor, the output of the motor generator 5 in addition to the output of the engine 3 is transmitted from the drive shaft 7 to the wheels 11, and assisted travel is performed.

Further, this hybrid vehicle is configured to cause the motor generator 5 to function as a generator (generator) at the time of deceleration or braking and convert kinetic energy into electric energy to charge the battery 13.

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

Returning to the explanation of the configuration, the in-vehicle battery pure resistance measuring apparatus 1 of the present embodiment is configured so that the discharge current of the battery 13 with respect to electric components such as the motor for assisted traveling and the motor generator 5 functioning as a starter motor. I or
A current sensor 15 that detects a charging current from the motor generator 5 that functions as a generator to the battery 13, and a voltage sensor 17 that has a resistance value of about 1 Mohm connected in parallel to the battery 13 and that detects a terminal voltage V of the battery 13. It has and.

In the in-vehicle battery pure resistance measuring apparatus 1 of this embodiment, the outputs of the current sensor 15 and the voltage sensor 17 described above are A / in the interface circuit (hereinafter abbreviated as "I / F") 21. A microcomputer (hereinafter abbreviated as “microcomputer”) 23 that is loaded after D conversion is further provided.

Then, the microcomputer 23 has the CPU 23
a, a RAM 23b, and a ROM 23c,
Of these, the CPU 23a includes a RAM 23b and a ROM.
23c, the I / F 21 is connected, and
The starter switch, ignition switch, accessory switch, and motor generator 5 not shown above
Other electrical equipment (load) switches, etc. are further connected.

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

The current value and the voltage value which are the outputs of the current sensor 15 and the voltage sensor 17 are sampled at a high speed in a short cycle and taken into the CPU 23a of the microcomputer 23 via the I / F 21 and taken in. The current value and the voltage value are collected in the data area (corresponding to a storage means) of the RAM 23b and used for various processes.

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 the flowchart of FIG.

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

When the initial setting in step S1 is completed,
Next, the CPU 23a determines whether or not the ignition (IG) switch is turned on (step S2), and when the determination is not YES, another process (step S3).
I do. In addition, in the processing of this step S3, 500 μ
The discharge current and the terminal voltage are also measured and collected in a sampling cycle of sec, and this processing is repeated until the determination in step S2 becomes YES. And IG
When it is detected that the switch is turned on (YES in step S2), the abruptly changing inrush current at the time of driving the abruptly changing starter motor can be measured.
Sampling cycle from 500μsec to 100μsec
(Step S4).

After that, the A / D conversion value of 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 is paired to form an I / F.
21 is read through, and the read actual data is stored in the RAM 2
An actual data collection process of storing, storing and collecting in the data area 3b is executed (step S5).

During the process of collecting the actual data in step S5, the peak value of the inrush current is detected by comparing the magnitude relationship between the collected and collected actual data (step S6). When the peak value is detected (YES in step S6), the time from the peak value detection is counted, actual data collection is continued until a predetermined time has elapsed, and when the predetermined time has elapsed (YES in step S7). )
Then, the actual data for a predetermined time before and after the peak value is held (step S8), and the sampling cycle is returned to the original 500 μsec after a predetermined time from the detection of the peak value (step S9).

Then, the collected and held actual data for a predetermined time is analyzed, and it is determined by applying the least squares method whether or not it is suitable for obtaining the quadratic approximation formula of the current-voltage characteristic. . That is, an analysis process is performed to analyze whether or not a discharge current that monotonically increases from 0 to a peak value and a discharge current that monotonically decreases from a peak value to a steady value are flowing from the battery (step S10).

As a result of the analysis in step S10, when the appropriate ones for obtaining the quadratic approximate expression of the current-voltage characteristic are collected (YES in step S11), the expressions for the increasing discharge current and the decreasing discharge current are obtained. Approximate curve formula calculation processing for obtaining a quadratic approximate formula of the current-voltage characteristic represented by (1) and (2) is executed (step S12).

A calculation process for obtaining the pure resistance of the battery is executed from the quadratic approximation formula obtained by the quadratic approximation curve formula calculation process in step S12 (step S13). In this calculation process, when the quadratic equation includes a voltage drop due to the concentration polarization component, a modified quadratic approximation formula calculation process for obtaining a modified quadratic approximation formula excluding this voltage drop is performed to correct this The calculation process for obtaining the pure resistance of the battery is executed by using the quadratic approximation formula. In this case, two modified quadratic approximations of the current-voltage characteristics with respect to the increasing discharge current and the decreasing discharge current are performed. After the differential value at the peak value of the formula is calculated, the intermediate value of the two differential values is calculated as the pure resistance of the battery. Since the obtained pure resistance of the battery is used for various purposes, RA
It is stored and stored in the data area of M23b (step S14). When the process of step S14 is completed, the process waits until the determination of step S2 becomes YES.

There are two methods for obtaining the intermediate value of the differential values depending on the flow type of the inrush current. When the time in the increasing direction of the rush current and the time in the decreasing direction are substantially equal to each other, the arithmetic mean of the two differential values is calculated as the pure resistance. On the other hand, when the time in the increasing direction of the inrush current and the time in the decreasing direction are significantly different, the differential value at the peak value of the modified quadratic approximation formula of the current-voltage characteristic with respect to the increasing discharge current is The differential value at the peak value of the two modified quadratic approximation formulas of the current-voltage characteristics for the decreasing discharge current is multiplied by the ratio of the increasing time of the increasing discharge current to the total time, and A calculation is performed to obtain the added value obtained by adding the value obtained by multiplying the value obtained by multiplying the time ratio of the decreasing discharge current flowing in the time, as the pure resistance. Whichever method is used to determine the pure resistance, the pure resistance of the battery is determined as an intermediate value between the two differential values.

In the example shown in the flowchart of FIG. 10, the first and second approximation formulas are both quadratic approximation formulas. However, when the first approximation formula is a first-order approximation formula, the modified approximation formula is Needless to say, the required processing is unnecessary. In this case, the slope of the linear equation is used instead of the differential value.

Further, in the on-vehicle battery pure resistance measuring apparatus 1 of the present embodiment, step S5 in the flow chart is the processing for the current / voltage measuring means in the claims, and step S12 is the approximate expression calculating means in the claims. The process corresponding to step S13 corresponds to the calculating means in the claims.

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

First, in the state where the battery 13 is being discharged when the starter motor starts to drive, when a rush current flows to the starter motor which exceeds the steady value and monotonically increases and monotonically decreases from the peak value to the steady value. The battery terminal voltage and discharge current are measured periodically.

In the on-vehicle battery pure resistance measuring apparatus 1 of the present embodiment, the actual data for a predetermined time before and after the periodically measured peak value is stored in the data area of the RAM 23b and is collected. , The collected actual data of the discharge current I and the terminal voltage V for a predetermined time are analyzed and are suitable for obtaining a quadratic approximate curve formula of the current-voltage characteristic by applying the least squares method. It is determined whether there is. That is, it is analyzed whether or not the discharge current flowing from the battery monotonously increases beyond the steady value and monotonically decreases from the peak value to the steady value or less.

Therefore, the approximate curve formula calculation process is not performed until the appropriate one for obtaining the quadratic approximate curve formula of the current-voltage characteristic is collected, and the approximate curve formula calculation process is already performed. Since it may be performed using the collected actual data for a predetermined time, it is not necessary to perform the processing in synchronization with the periodic measurement of the terminal voltage and the discharge current, and a high processing speed is not required.

In the above-described embodiment, the present invention is implemented by focusing only on the inrush current included in the discharge current when the starter motor is driven, but the starter motor is different from the starter motor in size. Similarly, the invention can be equally applied to loads other than the starter motor in which an inrush current flows at the start of driving. However, in this case, I
Instead of the G switch, the ON operation of the load switch is detected at the load driving start time and the process of step S4 is performed, and other processes may be performed by substantially the same process as the flowchart of FIG. .

In the above-described embodiment, the difference in the terminal voltage of the battery at the point where the discharge current is 0 in the first and second approximate expressions is such that the inrush current increases from 0 to the peak value, and then the peak value changes to 0. The voltage drop due to the total concentration polarization component generated during the reduced period is regarded as the voltage drop due to the concentration polarization component occurring until the inrush current occupying in this total concentration polarization component reaches the peak value from 0. The difference between the terminal voltage of the battery at the point where the discharge current is 0 in the formula is the current-time product from 0 to the peak value with respect to the current-time product when the inrush current increases from 0 to the peak value and decreases from the peak value to 0. Although it is calculated by multiplying by the ratio, it can be calculated by other methods, and the method will be described below.

In the first place, if the difference between the first approximation formula and the second approximation formula is the difference in the concentration polarization component, by taking the difference equation between the two formulas, the peak current from which the concentration polarization component becomes equal is obtained. With respect to the concentration polarization until the current value becomes 0, the difference between the two can be made conspicuous, and the change of the concentration polarization component from the current value 0 to the peak current value can be predicted based on the expression of this difference.

The difference between the above equations (1) and (2) is taken to obtain ΔV = V = (a1-a2) I ² + (b1-b2) I + (c1-c2) (21). When this is plotted, as shown in FIG. 11, the concentration polarization component becomes 0 at the point of the peak current value, and a curve showing only the change of the concentration polarization component up to the current value 0 is drawn. Then, by extending the curve drawn by the equation (21) to a point having a value twice the peak current value as shown by the dotted line, the change in the concentration polarization component from the current value 0 to the peak current value is shown. Predict. That is, the relative change in concentration polarization between current increase and current decrease is predicted based on the difference equation.

The expression of the difference is obtained by condensing the state of occurrence and change of the concentration polarization from the current value 0 to the peak current and the concentration polarization from the peak current to the current value 0 between the current value 0 and the peak current. Therefore, by extending the curve represented by this equation to the value of the discharge current that is doubled, the change in concentration polarization when the current flows from current value 0-peak value-current value You will be able to assume the situation. Therefore, the present invention can be effectively applied even when the proportional relationship between the current-time product and the concentration polarization is disturbed and the accuracy deteriorates when the concentration-polarization at an arbitrary point is estimated using the current-time product.

Therefore, the difference between the voltage value V0 at the point where the current value is 0 and the voltage value V2P at the point where the peak current value is double (V2P
-V0) The ratio of the difference (V2P-VP) between the voltage value VP at the peak current value and the voltage value at the point twice the peak current value (V2P-VP) is calculated, and this is approximated in the current increasing direction. The concentration polarization component at the point of the peak current value is predicted by multiplying the concentration polarization Vpolc0 at the current 0 (A) point, which is the voltage difference between the intercept of the curve and the intercept of the approximate curve in the direction of decreasing current. The concentration polarization component at this predicted peak current value can be treated in the same manner as Vpolcp described above, and a voltage drop curve of pure resistance and activation polarization can be obtained.

When deleting the concentration polarization component from the current decrease curve, it is possible to remove the concentration polarization component at the current peak value by the same method. That is, the voltage values at two points other than the peak value are obtained by equation (21), and the voltage value V0 at the point where the current value is 0 and the voltage value V2P at the point where the peak current value is doubled.
The ratio of the difference between the voltage value at two points other than the peak value and the voltage value at a point that is twice the current value of the peak current value with respect to the difference between The concentration polarization component at each point is predicted by multiplying the concentration polarization Vpolc0 at the current 0 (A) point, which is the voltage difference of the intercept of the approximate curve in the direction. By using the predicted concentration polarization components at the two points together with the concentration polarization components at the peak current value, it is possible to obtain a voltage rise curve only for pure resistance and activation polarization.

The method of obtaining the pure resistance by using the modified approximate expression of the voltage drop curve and the voltage rise curve obtained as described above is the same as the case of the modified approximate expression obtained by using the current-time product. The detailed description is omitted here.

[0098]

As described above, according to claims 1 and 13
According to the invention described, the period during which the inrush current is flowing in the constant load predetermined in the normal use state of the vehicle, the discharge current of the battery and the terminal voltage corresponding to this discharge current are periodically measured, The first approximate expression of the current-voltage characteristic for the increasing discharge current and the second approximate expression of the current-voltage characteristic for the decreasing discharge current showing the correlation between the discharge current and the terminal voltage obtained as a result of the measurement are obtained. , Between the two terminal voltage change values per unit current change at the points corresponding to the peak values of the first and second approximate expressions excluding the voltage drop due to the concentration polarization component in the first and second approximate expressions. Since the intermediate value thus obtained is calculated as the value of the pure resistance of the battery, the in-vehicle battery that can measure the pure resistance of the in-vehicle battery when the battery is used in a normal state, that is, even when the vehicle is in use Pure The measuring method and apparatus can be provided.

According to the above-mentioned invention of claim 2, the intermediate value to be obtained for measuring as the value of the pure resistance of the battery is the first and second values excluding the voltage drop due to the concentration polarization component.
Since the values of the two terminal voltage changes per unit current change at the point corresponding to the peak value of the approximate expression are calculated by averaging, An on-vehicle battery pure resistance measuring method capable of accurately measuring the pure resistance of an on-vehicle battery can be provided.

According to the above-mentioned invention of claim 3, the intermediate value to be obtained for measuring as the value of the pure resistance of the battery is the first and second values excluding the voltage drop due to the concentration polarization component.
The value of the two terminal voltage changes per unit current change at the point corresponding to the peak value of the approximate expression of was multiplied by the ratio of the monotonous increase period and the monotonous decrease period to the total time during which the inrush current flows. Since it is obtained by the above addition, it is possible to provide a vehicle-mounted battery pure resistance measuring method capable of accurately measuring the pure resistance of the vehicle-mounted battery when the changes in the activation polarization at the points corresponding to the peak values are not equal.

According to the invention described in claim 4, when the modified approximate expression is a linear expression, its slope is used, and when it is a quadratic expression, the intermediate value is obtained by using the differential value at the peak value. Since the resistance can be measured, it is possible to provide a vehicle battery pure resistance measuring method that can measure the resistance by a simple calculation.

According to the invention described in claim 5, the voltage value excluding the voltage drop is substituted into the first quadratic approximation equation and the equation in which the constant and the linear coefficient are equal to determine the quadratic coefficient. Since the quadratic equation is obtained as the first modified approximate expression, a modified approximate expression excluding the concentration polarization component can be obtained with high accuracy, and a vehicle battery pure resistance measuring method capable of accurately measuring pure resistance can be provided. Can be provided.

According to the invention described in claim 6, since the second quadratic modified approximate expression excluding the voltage drop due to the concentration polarization component can be easily obtained, the pure resistance can be measured without troublesome processing. It is possible to provide a vehicle-mounted battery pure resistance measuring method that can be performed.

According to the seventh aspect of the present invention, when both the first and second modified approximate expressions are quadratic expressions, a pure calculation is performed by a simple calculation to find an intermediate value of the differential value at the peak value. An on-vehicle battery pure resistance measuring method capable of measuring resistance can be provided.

According to the above-mentioned invention of claim 8, the second point of the quadratic equation is used by utilizing the zero point which originally does not include the concentration polarization component.
Since the modified approximate expression of is calculated, it is possible to provide the on-vehicle battery pure resistance measuring method that requires less processing for calculating the approximate expression excluding the concentration polarization component.

According to the above-mentioned invention of claim 9, since the slope of the second modified approximate expression is used for obtaining the intermediate value, the process for obtaining the intermediate value is simplified in the vehicle. A battery pure resistance measuring method can be provided.

According to the invention described in claim 10 described above,
Since the voltage drop due to the concentration polarization component at the point corresponding to the peak value in the total concentration polarization component is known and the voltage value corresponding to the peak value excluding the voltage drop due to the concentration polarization component is obtained, the concentration polarization component can be accurately determined. It is possible to obtain the first modified approximate expression that has been removed, and it is possible to provide a vehicle-mounted battery pure resistance measuring method that can accurately measure pure resistance.

According to the invention of claim 11 described above,
Similarly to the invention according to claim 10, the voltage drop due to the concentration polarization component at the point corresponding to the peak value in the total concentration polarization component is known, and the voltage value corresponding to the peak value excluding the voltage drop due to the concentration polarization component is obtained. Therefore, the first modified approximate expression excluding the concentration polarization component can be obtained with high accuracy, and the current-time product does not have to be obtained only by understanding the first and second approximate expressions. In-vehicle battery pure resistance measuring method that can measure pure resistance easily and accurately without being affected by the correspondence between current-time product and occurrence of concentration polarization, and without requiring complicated processing. Can be provided.

According to the invention of claim 12 described above,
When an inrush current that monotonically increases to a peak value flows in a short time without concentration polarization occurring, not only the process for measuring pure resistance becomes simple, but also an approximate expression can be easily obtained. An on-vehicle battery pure resistance measuring method can be provided.

[Brief description of drawings]

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

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

FIG. 3 is a graph showing an example of a discharge current accompanied by a rush current when starting the starter motor.

FIG. 4 is a graph showing an example of an IV characteristic represented by a quadratic approximation formula.

FIG. 5 is a graph for explaining an example of how to remove the concentration polarization component from the approximate expression in the increasing direction.

FIG. 6 is a graph for explaining an example of how to remove a concentration polarization component from an approximate expression in a decreasing direction.

FIG. 7 is a graph showing an example of an IV characteristic in which the increasing direction is represented by a linear approximation formula.

FIG. 8 is a graph for explaining another example of how to remove the concentration polarization component from the approximate expression in the decreasing direction.

FIG. 9 is a graph for explaining another example of how to remove a concentration polarization component from an approximate expression in the decreasing direction.

FIG. 10 is a flowchart showing a process performed by the microcomputer in FIG. 2 according to a predetermined program for pure resistance measurement.

FIG. 11 is a view for explaining a method of obtaining a concentration polarization component at a point that is a peak current value and an arbitrary point based on a difference equation obtained by taking a difference between equations (1) and (2). Is a graph of.

FIG. 12 is a graph showing an IV characteristic that generally shows the breakdown of the terminal voltage drop due to discharge.

FIG. 13 is a graph for explaining how to measure the pure resistance of a conventional battery.

[Explanation of symbols]

23a-1 Current / voltage measuring means (CPU) 23a-2 Approximate expression calculation means (CPU) 23a-3 Computing means (CPU)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01R 31/36 ZHV G01R 31/36 ZHVA F term (reference) 2G016 CA03 CB01 CB06 CB12 CB21 CB23 CB31 CC02 CC03 CC04 CC16 CC24 CC27 CC28 CD02 2G028 AA01 BE04 CG02 DH01 FK01 FK02 GL07 GL09 GL11 MS03 5H030 AA08 AS08 FF42 FF44 5H115 PA14 PC06 PG04 PI16 PI22 PI29 PO06 PU01 PU25 PU29 SE06 TI02 TI05 TI06 TI10

Claims (13)

[Claims] 1. An on-vehicle battery pure resistance measuring method for measuring a pure resistance of a battery mounted on a vehicle for supplying electric power to a load of the vehicle, wherein a predetermined constant load among the loads is from 0 to a peak value. After the inrush current that monotonically increases and then monotonically decreases from the peak value to the steady value, the discharge current of the battery and the terminal voltage corresponding to the discharge current are periodically measured, and the measured discharge current and A first approximate expression of a current-voltage characteristic with respect to the increasing discharge current and a second approximate expression of a current-voltage characteristic with respect to the decreasing discharge current showing a correlation with a terminal voltage are obtained, and the first and second When the voltage drop due to the concentration polarization component is included in the approximate expression of, the two terminal voltage changes per unit current change at the points corresponding to the peak values of the first and second approximate expressions excluding the voltage drop. Is obtained, and the obtained intermediate value is measured as the value of the pure resistance of the battery. 2. The in-vehicle battery pure resistance measuring method according to claim 1, wherein the intermediate value corresponds to the peak value of the first and second approximate expressions excluding a voltage drop due to the concentration polarization component. A method for measuring an on-vehicle battery pure resistance, which is characterized by averaging two terminal voltage change values per unit current change at a point. 3. The in-vehicle battery pure resistance measuring method according to claim 1, wherein the intermediate value is a unit current at a point corresponding to the peak value of the first and second approximate expressions excluding the voltage drop. It is obtained by multiplying the values of the two terminal voltage changes per change by the respective ratios of the time of the monotonous increasing period and the time of the monotonic decreasing period to the total time during which the inrush current flows, and then adding them. In-vehicle battery pure resistance measurement method. 4. The in-vehicle battery pure resistance measuring method according to claim 1, wherein when the first and second approximate expressions are quadratic expressions, the intermediate value is determined when the intermediate value is obtained. First and second values obtained by removing the voltage drop due to the concentration polarization component from the first and second approximate expressions
Of the first and second modified approximate expressions, and a value of two terminal voltage changes per unit current change at a point corresponding to the peak value of the first and second modified approximate expressions is measured. Method. 5. The in-vehicle battery pure resistance measuring method according to claim 4, wherein a difference between the terminal voltages of the battery at a point where the discharge currents of the first and second approximate expressions are 0 is obtained, and the difference is the inrush value. Considered as a voltage drop due to the total concentration polarization component generated during the period in which the current increased from 0 to the peak value and decreased from the peak value to 0, the inrush current occupying in the total concentration polarization component occurred before reaching the peak value from 0. The voltage drop due to the concentration polarization component is obtained, and a value obtained by removing the obtained voltage drop from the voltage value corresponding to the peak value is substituted into a formula in which a constant and a linear coefficient are equal to the first quadratic approximation formula. A vehicle-mounted battery pure resistance measuring method, characterized in that a quadratic equation in which a quadratic coefficient is determined is obtained as the first modified approximate equation. 6. The in-vehicle battery pure resistance measuring method according to claim 5, wherein in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the voltage drop due to the concentration polarization component between the peak value and 0 is obtained. Is obtained, and a quadratic equation in which a coefficient is determined using the three voltage values is obtained as the second modified approximation equation. 7. The in-vehicle battery pure resistance measuring method according to claim 6, wherein differential values at peak values of the first and second modified approximate expressions are used to obtain the intermediate value. In-vehicle battery pure resistance measurement method. 8. The in-vehicle battery pure resistance measuring method according to claim 5, wherein in addition to the voltage value excluding the voltage drop due to the concentration polarization component in the peak value, a zero point and an intermediate point between the peak value and 0 are measured. A two-dimensional voltage value excluding a voltage drop due to a concentration polarization component is obtained, and a quadratic equation in which a coefficient is determined using the three voltage values is obtained as the second modified approximate equation. Resistance measurement method. 9. The in-vehicle battery pure resistance measuring method according to claim 5, wherein, in addition to the voltage value excluding the voltage drop due to the concentration polarization component at the peak value, the concentration polarization component at an intermediate point between the peak value and 0. The voltage value excluding the voltage drop due to
A vehicle-mounted battery pure resistance measuring method characterized in that a linear expression determined by connecting points is obtained as the second modified approximate expression, and the slope of the second modified approximate expression is used to obtain the intermediate value. . 10. The in-vehicle battery pure resistance measuring method according to claim 5, wherein the voltage drop due to the concentration polarization component that occurs until the inrush current in the total concentration polarization component reaches a peak value from 0. Is the current time when the inrush current increases from 0 to a peak value and then decreases from the peak value to 0 to the difference in the terminal voltage of the battery at the point where the discharge current is 0 in the first and second approximate expressions. An in-vehicle battery pure resistance measuring method, which is obtained by multiplying by a ratio of a current-time product from 0 to a peak value with respect to a product. 11. The in-vehicle battery pure resistance measuring method according to claim 5, wherein a difference equation between the two equations is obtained from the first and second approximation equations and occupies the total concentration polarization component. The voltage drop due to the concentration polarization component that occurs until the inrush current reaches a peak value from 0 is defined as the difference between the terminal voltage of the battery at the point where the discharge current of the first and second approximate expressions is 0. The difference between the voltage value at the point where the current value is 0 and the voltage value at the point where the current value is twice the peak current value obtained based on the formula An in-vehicle battery pure resistance measuring method, which is obtained by multiplying a ratio of a difference between a voltage value at a point having a double current value and a voltage value. 12. The in-vehicle battery pure resistance measuring method according to claim 1, wherein the constant load is an inrush current that monotonically increases to a peak value in a short time without occurrence of concentration polarization. And the first approximate expression is a linear expression, and the slope of the first approximate expression is used to obtain the intermediate value. 13. An in-vehicle battery pure resistance measuring device for measuring a pure resistance of a battery mounted on a vehicle for supplying electric power to a load of the vehicle, wherein a predetermined constant load among the loads is from 0 to a peak value. A current / voltage measuring means for periodically measuring the discharge current of the battery and the terminal voltage corresponding to the discharge current, during which the inrush current that monotonically increases and then monotonically decreases from the peak value to the steady value is flowing, A first approximation formula of the current-voltage characteristic for the increasing discharge current showing the correlation between the discharge current measured by the current / voltage measuring means and the terminal voltage, and a second approximation formula of the current-voltage characteristic for the decreasing discharge current. An approximation formula calculating means for obtaining an approximation formula, and, when the first and second approximation formulas include a voltage drop due to a concentration polarization component, before the first and second approximation formulas excluding the voltage drop. And a calculation means for calculating an intermediate value of two terminal voltage change values per unit current change at a point corresponding to the peak value, and the intermediate value calculated by the calculation means is measured as a pure resistance value of the battery. An in-vehicle battery pure resistance measuring device characterized by: