JP2021021629A - Battery internal resistance measurement device and measurement method - Google Patents

Abstract

To measure internal resistance between both ends of one or more secondary batteries among batteries consisting of n pieces of serially-connected secondary batteries.SOLUTION: A battery internal resistance measurement device comprises: a ripple voltage generation unit for grouping n pieces of secondary batteries into a first battery group on a low potential side and a second battery group on a high potential side to control the first battery group and the second battery group to alternately perform discharge and discharge stop; one or two resistance elements having a predetermined resistance value, which is/are connected such that discharge current of the first battery group or discharge current of the second battery group flows therethrough; a first voltage measurement unit for performing measurement for deriving voltage between both ends of the first battery group; a second voltage measurement unit for performing measurement for deriving voltage between both ends of the second battery group; and a ripple voltage measurement unit for measuring ripple voltage between both ends of one or more secondary batteries in the first battery group or the second battery group.SELECTED DRAWING: Figure 1

Description

The present invention relates to a battery internal resistance measuring device and a measuring method configured by connecting a plurality of secondary batteries in series.

A method of measuring the internal resistance of each secondary battery is known in order to determine the quality of a battery composed of a plurality of secondary batteries connected in series. The secondary battery quality determination device described in Patent Document 1 measures the current I flowing when a charger and a load are connected between both ends of a battery composed of a plurality of secondary batteries connected in series, while individual two. The internal resistance of each secondary battery is obtained by passing a constant AC current through the secondary battery, measuring the ripple voltage vr between both ends, and dividing vr / I.

Japanese Unexamined Patent Publication No. 2003-121516

However, a Hall element or a shunt resistor is usually used to measure the current I flowing between both ends of the battery. Hall elements are expensive. In addition, the shunt resistance has poor sensitivity, and accurate measurement cannot be performed. Moreover, it is difficult to support a wide range of current measurement.

An object of the present invention is to provide an apparatus and a method for measuring the internal resistance of each secondary battery contained in a battery composed of a plurality of secondary batteries connected in series with high accuracy, easily and at low cost. Is.

In order to achieve the above object, the present invention provides the following configurations.
An aspect of the present invention is for measuring the internal resistance between both ends of one or a plurality of secondary batteries in a battery composed of n (n is a natural number of 2 or more) secondary batteries connected in series. It ’s a device,
The n secondary batteries are divided into two battery groups, a first battery group on the low potential side and a second battery group on the high potential side, with respect to the first battery group and the second battery group. A ripple voltage generator that controls discharge and discharge stop alternately,
One or two resistance elements having a predetermined resistance value connected so that the discharge current of the first battery group or the discharge current of the second battery group flows.
A first voltage measuring unit that performs measurement for deriving the voltage between both ends of the first battery group, and
A second voltage measuring unit that performs measurement for deriving the voltage between both ends of the second battery group, and
A ripple voltage measuring unit that measures the ripple voltage between both ends of the first battery group or one or a plurality of secondary batteries in the first battery group or the second battery group generated by the control of the ripple voltage generating unit. It is characterized by having.
-In the above embodiment, the value of the discharge current is calculated by dividing the voltage between both ends of the first battery group or the second battery group by the resistance value of the resistance element, and the measured ripple voltage is obtained. It is preferable to calculate the internal resistance of the one or more secondary batteries by dividing by the value of the discharge current.
-In the above embodiment, the two resistance elements are provided, the discharge current of the first battery group flows through one of the resistance elements, and the discharge current of the second battery group flows through the other resistance element. It is suitable.
-In the above embodiment, it is preferable to have one resistance element, and the discharge current of the first battery group and the discharge current of the second battery group alternately flow through the resistance element.
In the above embodiment, the first voltage measuring unit measures the voltage division of the voltage between both ends of the first battery group, and the voltage between both ends of the first battery group is calculated based on the measured voltage division. It is preferable to derive it.
-In the above embodiment, the second voltage measuring unit measures the voltage division of the voltage between both ends of the battery, and the voltage between both ends of the battery is derived based on the measured voltage division, and the derived battery is derived. It is preferable that the voltage between both ends of the second battery group is derived based on the voltage between both ends of the first battery group and the voltage between both ends of the first battery group.
-In the above embodiment, the ripple voltage generation unit switches the continuity and interruption of the discharge current path of the first battery group and the conduction and interruption of the first switch element and the discharge current path of the second battery group. It is preferable to have a second switch element for switching.
-Another aspect of the present invention is to measure the internal resistance between both ends of one or more secondary batteries in a battery consisting of n (n is a natural number of 2 or more) secondary batteries connected in series. Is a way to
The n secondary batteries are divided into two battery groups, a first battery group on the low potential side and a second battery group on the high potential side, with respect to the first battery group and the second battery group. A ripple voltage is generated in each secondary battery by alternately discharging and stopping the discharge.
The discharge current of the first battery group or the discharge current of the second battery group is passed through one or two resistance elements having a predetermined resistance value.
Measurements were made to derive the voltage across the first battery group.
The measurement for deriving the voltage between both ends of the second battery group was performed.
It is characterized in that the ripple voltage between both ends of the first battery group or one or a plurality of secondary batteries in the second battery group is measured.

INDUSTRIAL APPLICABILITY According to the present invention, a device and a method for measuring the internal resistance of each secondary battery included in a plurality of secondary batteries connected in series with high accuracy, simplicity and low cost are realized.

FIG. 1 shows the configuration of the first embodiment of the battery internal resistance measuring device according to the present invention. FIG. 2 is a diagram illustrating the operation of the measuring device of FIG. FIG. 3 is a diagram illustrating the operation of the measuring device of FIG. FIG. 4 shows the configuration of the second embodiment of the battery internal resistance measuring device according to the present invention. FIG. 5 is a diagram illustrating the operation of the measuring device of FIG. FIG. 6 is a diagram illustrating the operation of the measuring device of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings shown as examples.
(1) Circuit Configuration of First Embodiment (1-1) FIG. 1 shows the configuration of the first embodiment of the internal resistance measuring device for a battery according to the present invention. FIG. 1 also shows the battery B to be measured. The battery B is composed of n (n is a natural number of 2 or more) secondary batteries b _{1 to} b _n connected in series. Each secondary battery b _{1 to} b _n is, for example, a lead storage battery, a lithium ion battery, or the like. Each of the secondary batteries b _{1 to} b _n may be a single cell or an assembled battery (a plurality of single cells are housed in one package). In principle, a single cell and an assembled battery may be mixed. In the illustrated example, each secondary battery b _{1 to} b _n is an assembled battery. Each of the secondary batteries b _{1 to} b _n constituting the battery B can be replaced with another secondary battery when it is determined to be deteriorated.

The measurement target of the battery internal resistance measuring device 10 according to the present invention is typically the internal resistance of each of the secondary batteries b _{1 to} b _n constituting the battery B. In principle, not only can the internal resistance of one secondary battery be measured, but also the internal resistance between both ends of a plurality of (for example, two or three) secondary batteries connected in series (of each secondary battery). The sum of internal resistances) can also be measured.

In FIG. 1, the battery B is being charged by a charger (not shown), and charging voltages + Vin and −Vin are applied to the high potential end and the low potential end, respectively. The internal resistance measuring device 10 can measure even while the battery B is being charged. Further, the internal resistance measuring device 10 can measure even when the battery B is discharging with respect to a load (not shown).

In the measurement method using the internal resistance measuring device 10, the n secondary batteries b _{1 to} b _n of the battery B are 2 of the first battery group B1 on the low potential side and the second battery group B2 on the high potential side. It is divided into two battery groups. The first battery group B1 includes the secondary batteries b _{1 to} b _k , and the second battery group B 2 includes the secondary batteries b _{k + 1 to} b _n . Here, k is a natural number of 1 or more and n-1 or less. The number of secondary batteries included in the two battery groups B1 and B2 does not have to be the same, and in principle, both battery groups may include at least one secondary battery.

The internal resistance measuring device 10 has terminals 1, terminals 2 and terminals 3 connected to both ends of the battery group B1 and both ends of the battery group B2 at the time of measurement. The terminal 1 is connected to the low potential end of the battery group B1, the terminal 2 is connected to the high potential end of the battery group B1 and the low potential end of the battery group B2, and the terminal 3 is connected to the high potential end of the battery group B2. Here, the potential of the terminal 1 is used as the reference potential.

A resistance element R1 and a switch element Q1 are connected in series between the terminals 1 and 2. The resistance element R1 and the switch element Q1 form a discharge current path of the battery group B1. The resistance element R1 has a predetermined resistance value appropriately selected according to the measurement range. The switch element Q1 is an N-channel MOSFET as an example, and the drain is connected to the resistance element R1 and the source is connected to the terminal 1. By applying a predetermined control signal va to the gate which is the control end of the switch element Q1, the conduction and interruption of the current path between the drain sources, that is, the discharge current path of the battery group B1 is switched.

A resistance element R2 and a switch element Q2 are connected in series between the terminals 2 and 3. The resistance element R2 and the switch element Q2 form a discharge current path of the battery group B2. The resistance element R2 has a predetermined resistance value appropriately selected according to the measurement range. The resistance value of the resistance element R2 may be the same as or different from the resistance value of the resistance element R1. The switch element Q2 is an N-channel MOSFET as an example, and the drain is connected to the resistance element R2 and the source is connected to the terminal 2. By applying a predetermined control signal vb to the gate which is the control end of the switch element Q2, the conduction and interruption of the current path between the drain sources, that is, the discharge current path of the battery group B2 is switched.

The switch elements Q1 and Q2 correspond to a ripple voltage generating unit that generates a ripple voltage in the battery B by controlling the battery groups B1 and B2 to alternately discharge and stop discharging. Here, "alternately" means that discharge and discharge stop are repeated in each of the battery groups B1 and B2, and that when the battery group B1 is discharged, the battery group B2 is discharged and vice versa. Includes both meanings of. In that case, the discharge current of the battery group B1 flows through the resistance element R1, and the discharge current of the battery group B2 flows through the resistance element R2.

Further, the voltage dividing resistor elements r1 and r2 are connected in series between the terminals 1 and 2. The voltage dividing resistor elements r1 and r2 are provided to measure the voltage dividing of the voltage between both ends of the battery group B1, and the first voltage dividing V1 is acquired from the connection point of the voltage dividing resistor elements r1 and r2.

The voltage dividing resistor elements r1 and r2 correspond to the first voltage measuring unit that performs measurement in order to derive the voltage between both ends of the battery group B1.

Further, a voltage dividing resistor element r3 and r4 are connected in series between the terminal 1 and the terminal 3. The voltage dividing resistor elements r3 and r4 are provided to measure the voltage dividing of the voltage between both ends of the battery B, and the second voltage dividing V2 is acquired from the connection point of the voltage dividing resistor elements r3 and r4.

The voltage dividing resistor elements r1 and r2 and the voltage dividing resistor elements r3 and r4 described above correspond to a second voltage measuring unit that performs measurement for deriving the voltage between both ends of the battery group B2.

The internal resistance measuring device 10 further includes voltmeters M _{1 to} M _k for measuring the ripple voltage between both ends of each of the secondary batteries b _{1 to} b _{k in} the battery group B ₁ , and each in the battery group B 2. It has a voltmeter M _{k + 1 to} M _n for measuring the ripple voltage between both ends of the secondary battery b _{k + 1 to} b _n . The ripple voltage here causes the AC voltage components generated in the battery B, that is, the secondary batteries b _{1 to} b _n , by alternately discharging and stopping the discharge at a constant frequency for the battery groups B1 and B2. It means the generated AC voltage component. Voltmeters M _{1 to} M _n correspond to a ripple voltage measuring unit. The voltmeters M _{1 to} M _n may be incorporated in the internal resistance measuring device 10 as shown in the figure, or may be an external device.

In the illustrated example, n voltmeters M _{1 to} M _n are provided corresponding to each of the _n secondary batteries b _{1 to} b _n . However, only one voltmeter is required, and one voltmeter can be used to sequentially measure the ripple voltage between both ends of the secondary batteries b _{1 to} b _n . The target for measuring the ripple voltage does not necessarily have to be one secondary battery, and if necessary, the distance between both ends of a plurality of series-connected secondary batteries in the battery group B1 or the battery group B2 is measured. May be good.

Although details will be described later, the internal resistance of one or a plurality of secondary batteries between both ends can be calculated by measuring the ripple voltage between both ends of an arbitrary number of secondary batteries. When the ripple voltage of one secondary battery is measured, the internal resistance of the secondary battery can be calculated, and when the ripple voltage of multiple secondary batteries is measured, the sum of the internal resistances of those secondary batteries is calculated. Can be calculated.

Although not shown, the internal resistance measuring device 10 has a calculation processing unit that performs a predetermined calculation based on the measured value, and a signal generation unit that generates control signals va and vb. Further, it may have a display unit for displaying the measurement result. The arithmetic processing unit, the signal generation unit, the display unit, and the like may be incorporated in the internal resistance measuring device 10 or may be connected as an external device.

(1-2) Circuit Operation With reference to FIGS. 2 and 3, the operation of the internal resistance measuring device 10 shown in FIG. 1 and the method of deriving the internal resistance of the battery will be described. 2 and 3 show a state in which the internal resistance measuring device 10 is connected to the battery B for measurement.

The control signal va of the switch element Q1 and the control signal vb of the switch element Q2 shown in FIG. 1 are, for example, PWM signals having the same frequency but different phases by 180 °. In that case, the duty ratio is set to less than 50% so that the switch elements Q1 and Q2 do not conduct at the same time. By using such control signals va and vb, the switch elements Q1 and Q2 are alternately conducted or cut off.

In FIG. 2, the current flowing through the circuit when the switch element Q1 is conductive (on) and the switch element Q2 is cut off (off) is shown by a line with an arrow.

When the switch element Q1 becomes conductive, the discharge current i1 flows in the current path including the resistance element R1 and the switch element Q1 due to the voltage V3 between both ends of the battery group B1. Since the switch element Q2 is cut off, the battery group B2 is in the discharge stopped state, and no current flows through the resistance element R2.

Further, due to the voltage V3 between both ends of the battery group B1, the measurement current i2 flows in the current path including the voltage dividing resistor elements r1 and r2. The voltage divider V1 of the voltage V3 is acquired from the connection point of the resistors r1 and r2. Further, the measurement current i3 flows in the current path including the voltage dividing resistance elements r3 and r4 due to the voltage V4 between both ends of the battery B. The voltage divider V2 of the voltage V4 is acquired from the connection point of the resistors r3 and r4.

The measurement currents i2 and i3 are always flowing regardless of whether the switch elements Q1 and Q2 are on or off. The resistances r1 to r4 are selected so that the measurement currents i2 and i3 are sufficiently smaller than the discharge current i1 so as not to affect the measurement accuracy of the internal resistance.

Discharge current i1 is a current flowing through each of the secondary batteries _b 1 ~b _k groups of cells B1. As shown in Equation 1 below, the discharge current i1 is calculated by dividing the voltage V3 between both ends of the battery group B1 by the resistance value of the resistance element R1.
i1 = V3 / R1 ・ ・ ・ Equation 1

The voltage V3 between both ends of the battery group B1 and the partial pressure V1 have the following relationship.
V3 = ((r1 + r2) / r2) * V1 ・ ・ ・ Equation 2

From Equations 1 and 2, the discharge current i1 is expressed as follows.
i1 = (((r1 + r2) / r2) * V1) / R1 ... Equation 3

The resistance elements R1, r1 and r2 are circuit constants, and the partial pressure V1 is a measured value. Therefore, Equation 3 means that the value of the discharge current i1 can be calculated by measuring the partial pressure V1.

Next, in FIG. 3, the current flowing through the circuit when the switch element Q1 is cut off (off) and the switch element Q2 is conductive (on) is shown by a line with an arrow.

When the switch element Q2 becomes conductive, the discharge current i4 flows in the current path including the resistance element R2 and the switch element Q2 due to the voltage between both ends of the battery group B2. The voltage between both ends of the battery group B2 is a value obtained by subtracting the voltage V3 between both ends of the battery group B1 from the voltage V4 between both ends of the battery B. Since the switch element Q1 is cut off, the battery group B1 is in the discharge stopped state, and no current flows through the resistance element R1.

Further, the measurement current i2 flows in the current path including the voltage dividing resistance elements r1 and r2. The voltage divider V1 of the voltage V3 is acquired from the connection point of the resistors r1 and r2. Further, the voltage V4 between both ends of the battery B causes the measurement current i3 to flow in the current path including the voltage dividing resistor elements r3 and r4. The voltage divider V2 of the voltage V4 is acquired from the connection point of the resistors r3 and r4.

The discharge current i4 is a current flowing through each of the secondary batteries b _{k + 1 to} b _n of the battery group B2. As shown in Equation 4 below, the discharge current i4 is calculated by dividing the voltage V4-V3 between both ends of the battery group B2 by the resistance value of the resistance element R2.
i4 = (V4-V3) / R2 ・ ・ ・ Equation 4

The voltage V4-V3 between both ends of the battery group B2 and the partial pressure V1 and the partial pressure V2 have the following relationship.
V4-V3 = ((r3 + r4) / r4) * V2-((r1 + r2) / r2) * V1
... Equation 5

From Equations 4 and 5, the discharge current i4 is expressed as follows.
i4 = (((r3 + r4) / r4) * V2-((r1 + r2) / r2) * V1) / R2
... Equation 6

The resistance elements R2, r1, r2, r3, and r4 have circuit constants, and the partial pressures V1 and V2 are measured values. Therefore, Equation 6 means that the value of the discharge current i4 can be calculated by measuring the partial pressures V1 and V2.

While repeating the alternating discharge and discharge stop of the battery groups B1 and B2 shown in FIGS. 2 and 3, the ripple voltages vr ₁ to each of the secondary batteries b _{1 to} b _n are measured by the voltmeters M _{1 to} M _n. Measure vr _n .

A ripple voltage _vr 1 to VR _n that is measured, using the current i4 of the current i1 and formula 6 of the formula 3, the internal resistance _ri 1 to Ri _n of each of the secondary battery _b 1 ~b _n, as follows Can be calculated for each.
ri ₁ = vr ₁ / i1
:
ri _k = _{vr k} / i1
rik _{+ 1} = vr _{k + 1} / i4
:
ri _n = _{vr n} / i4 ··· formula 7
That is, the internal resistance of the secondary battery is obtained by dividing the ripple voltage of the battery by the value of the current flowing through the battery.

Although not shown, calculations such as the above-mentioned equations 1 to 7 can be performed by an appropriate calculation processing unit incorporated in the internal resistance measuring device 10 or connected as an external device. Such an arithmetic processing unit has a CPU that has an arithmetic function and an appropriate storage device. The storage device stores the resistance value of each resistance element, which is a circuit constant.

After the internal resistance ri ₁ to Ri _n of each of the secondary batteries as in Equation 7 is calculated, it is possible to determine deterioration of the secondary battery. A secondary battery that exhibits an internal resistance exceeding the specified value is determined to be deteriorated and can be replaced.

The internal resistance measuring device 10 of the present invention does not directly measure the current flowing through the battery B. Instead, the voltage between both ends of the two battery groups B1 and B2 is derived by voltage division measurement, the ripple voltage of each secondary battery generated by the ripple voltage generator is measured, and their measured values and circuit constants are measured. The internal resistance of each secondary battery can be calculated by using the resistance value of the resistance element. Therefore, in the present invention, a Hall element or a shunt resistor for measuring the current is unnecessary. Further, since it is only necessary to perform stable voltage measurement of the battery B or the secondary batteries b _{1 to} b _n contained therein, extremely high-precision measurement becomes possible.

When measuring various batteries using one internal resistance measuring device 10, it is necessary to correspond to a wide range of discharge currents i1 and i4. In that case, a wide measurement range can be supported by changing the resistance values of the resistance elements R1 and R2. As an example, a plurality of resistance elements having different resistance values can be switched by a mechanical switch, and optimum measurement can be performed by selecting resistance elements R1 and R2 having appropriate resistance values from them. ..

(2) Circuit Configuration of Second Embodiment (2-1) FIG. 4 shows the configuration of a second embodiment of the internal resistance measuring device for a battery according to the present invention. Regarding the second embodiment, the points different from those of the first embodiment will be mainly described, and the common points may be omitted. In FIG. 4, the same components as those in the first embodiment are indicated by the same reference numerals.

The internal resistance measuring device 20 of the second embodiment is provided with one resistance element R3 having a predetermined resistance value instead of the two resistance elements R1 and R2 of the first embodiment.

A resistance element R3 and a switch element Q1 are connected in series between the terminals 1 and 2. Further, a resistance element R3 and a switch element Q2 are connected in series between the terminal 2 and the terminal 3. The resistance element R3 is used for both the discharge current path of the battery group B1 and the discharge current path of the battery group B2.

The switch elements Q1 and Q2 correspond to a ripple voltage generating unit that generates a ripple voltage in the battery B by alternately discharging and stopping the discharge of the battery groups B1 and B2. In that case, the discharge current of the battery group B1 and the discharge current of the battery group B2 flow alternately (but in opposite directions) to the resistance element R3. Other configurations are the same as in the first embodiment.

(2-2) Circuit Operation With reference to FIGS. 5 and 6, the operation of the internal resistance measuring device 20 shown in FIG. 4 and the method of deriving the internal resistance of the battery will be described. 5 and 6 show a state in which the internal resistance measuring device 20 is connected to the battery B for measurement.

The control signal va of the switch element Q1 and the control signal vb of the switch element Q2 shown in FIG. 4 are the same as those in the first embodiment. The switch elements Q1 and Q2 alternately conduct or cut off.

In FIG. 5, the current flowing through the circuit when the switch element Q1 is conductive (on) and the switch element Q2 is cut off (off) is shown by a line with an arrow.

When the switch element Q1 becomes conductive, the discharge current i1 flows in the current path including the resistance element R3 and the switch element Q1 due to the voltage V3 between both ends of the battery group B1. Since the switch element Q2 is shut off, the battery group B2 is in the discharge stopped state. The measurement currents i2 and i3 are the same as those in the first embodiment, and the partial pressure V1 and the partial pressure V2 are acquired.

Discharge current i1 is a current flowing through each of the secondary batteries _b 1 ~b _k groups of cells B1. As shown in Equation 11 below, the discharge current i1 is calculated by dividing the voltage V3 between both ends of the battery group B1 by the resistance value of the resistance element R3.
i1 = V3 / R3 ・ ・ ・ Equation 11

The voltage V3 between both ends of the battery group B1 and the partial pressure V1 have the following relationship.
V3 = ((r1 + r2) / r2) * V1 ・ ・ ・ Equation 12

From Equations 11 and 12, the discharge current i1 is expressed as follows.
i1 = (((r1 + r2) / r2) * V1) / R3 ・ ・ ・ Equation 13

The resistance elements R3, r1 and r2 are circuit constants, and the partial pressure V1 is a measured value. Therefore, Equation 13 means that the value of the discharge current i1 can be calculated by measuring the partial pressure V1.

Next, FIG. 6 shows the current flowing through the circuit when the switch element Q1 is cut off (off) and the switch element Q2 is conductive (on) by a line with an arrow.

When the switch element Q2 becomes conductive, the discharge current i4 flows in the current path including the resistance element R3 and the switch element Q2 due to the voltage between both ends of the battery group B2. The voltage between both ends of the battery group B2 is obtained by subtracting the voltage V3 between both ends of the battery group B1 from the voltage V4 between both ends of the battery B. Since the switch element Q1 is shut off, the battery group B1 is in the discharge stopped state. The measurement currents i2 and i3 are the same as those in the first embodiment, and the partial pressure V1 and the partial pressure V2 are acquired.

The discharge current i4 is a current flowing through each of the secondary batteries b _{k + 1 to} b _n of the battery group B2. As shown in the following equation 14, the discharge current i4 is calculated by dividing the voltage V4-V3 between both ends of the battery group B2 by the resistance value of the resistance element R3.
i4 = (V4-V3) / R3 ・ ・ ・ Equation 14

The voltage V4-V3 between both ends of the battery group B2 and the partial pressure V1 and the partial pressure V2 have the following relationship.
V4-V3 = ((r3 + r4) / r4) * V2-((r1 + r2) / r2) * V1
... Equation 15

From equations 14 and 15, the discharge current i4 is expressed as follows.
i4 = (((r3 + r4) / r4) * V2-((r1 + r2) / r2) * V1) / R3
... Equation 16

The resistance elements R3, r1, r2, r3, and r4 have circuit constants, and the partial pressures V1 and V2 are measured values. Therefore, Equation 16 means that the value of the discharge current i4 can be calculated by measuring the partial pressures V1 and V2.

While repeating the alternating discharge and discharge stop of the battery groups B1 and B2 shown in FIGS. 5 and 6, the ripple voltages vr ₁ to each of the secondary batteries b _{1 to} b _n are measured by the voltmeters M _{1 to} M _n. Measure vr _n .

A ripple voltage _vr 1 to VR _n that is measured, using the current i4 of the current i1 and formula 16 of the formula 13, the internal resistance _ri 1 to Ri _n of each of the secondary battery _b 1 ~b _n, as follows Can be calculated for each.
ri ₁ = vr ₁ / i1
:
ri _k = _{vr k} / i1
rik _{+ 1} = vr _{k + 1} / i4
:
ri _n = _{vr n} / i4 ··· formula 17
That is, the internal resistance of the secondary battery is obtained by dividing the ripple voltage of the battery by the value of the current flowing through the battery.

The effects of the present invention described for the first embodiment also apply to the second embodiment. In addition, the illustrated configuration of the present invention is an example, and various modifications can be made within a range in line with the gist of the present invention.

1, 2, 3 terminals R1, R2, R3 Resistance element r1, r2, r3, r4 Pressure division resistance element Q1, Q2 Switch element B Battery B1 First battery group B2 Second battery group b _{1 to} b _n Secondary Battery M _{1 to} M _n voltmeter

Claims (8)

A device for measuring the internal resistance between both ends of one or a plurality of secondary batteries in a battery consisting of n (n is a natural number of 2 or more) secondary batteries connected in series.
The n secondary batteries are divided into two battery groups, a first battery group on the low potential side and a second battery group on the high potential side, with respect to the first battery group and the second battery group. A ripple voltage generator that controls discharge and discharge stop alternately,
One or two resistance elements having a predetermined resistance value connected so that the discharge current of the first battery group or the discharge current of the second battery group flows.
A first voltage measuring unit that performs measurement for deriving the voltage between both ends of the first battery group, and
A second voltage measuring unit that performs measurement for deriving the voltage between both ends of the second battery group, and
A ripple voltage measuring unit that measures the ripple voltage between both ends of the first battery group or one or a plurality of secondary batteries in the first battery group or the second battery group generated by the control of the ripple voltage generating unit. An internal resistance measuring device for a battery, characterized by having. The value of the discharge current is calculated by dividing the voltage between both ends of the first battery group or the second battery group by the resistance value of the resistance element, and the measured ripple voltage is the value of the discharge current. The battery internal resistance measuring device according to claim 1, wherein the internal resistance of the one or a plurality of secondary batteries is calculated by dividing by. The first aspect of the invention is characterized in that the two resistance elements are provided, the discharge current of the first battery group flows through one of the resistance elements, and the discharge current of the second battery group flows through the other resistance element. Or the battery internal resistance measuring device according to 2. The invention according to claim 1 or 2, wherein the resistance element has one, and the discharge current of the first battery group and the discharge current of the second battery group alternately flow through the resistance element. Battery internal resistance measuring device. The first voltage measuring unit measures the voltage division of the voltage between both ends of the first battery group, and the voltage between both ends of the first battery group is derived based on the measured voltage division. The internal resistance measuring device for a battery according to any one of claims 1 to 4. The second voltage measuring unit measures the voltage division of the voltage between both ends of the battery, and the voltage between both ends of the battery is derived based on the measured voltage division, and the voltage between both ends of the battery is derived. The internal resistance measuring device for a battery according to claim 5, wherein the voltage between both ends of the second battery group is derived based on the voltage between both ends of the first battery group. The ripple voltage generation unit switches between a first switch element that switches the continuity and interruption of the discharge current path of the first battery group and a second switch that switches the continuity and interruption of the discharge current path of the second battery group. The battery internal resistance measuring device according to any one of claims 1 to 6, further comprising an element. A method for measuring the internal resistance between both ends of one or a plurality of secondary batteries in a battery consisting of n (n is a natural number of 2 or more) secondary batteries connected in series.
The n secondary batteries are divided into two battery groups, a first battery group on the low potential side and a second battery group on the high potential side, with respect to the first battery group and the second battery group. A ripple voltage is generated in each secondary battery by alternately discharging and stopping the discharge.
The discharge current of the first battery group or the discharge current of the second battery group is passed through one or two resistance elements having a predetermined resistance value.
Measurements were made to derive the voltage across the first battery group.
The measurement for deriving the voltage between both ends of the second battery group was performed.
A method for measuring the internal resistance of a secondary battery, which comprises measuring the ripple voltage between both ends of the first battery group or one or a plurality of secondary batteries in the second battery group.

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