JPH0817478A - Power storing secondary battery charge/discharge current measuring method, remaining power amount measuring method, and device for it - Google Patents

Abstract

PURPOSE:To accurately measure and evaluate the residual capacity of a secondary battery with a low-cost measuring circuitry configuration without use of any high precision insulated amplifier etc. CONSTITUTION:At the time of charging and discharging a secondary battery 1, currents in different directions flowing in a charge/discharge circuit 2 are fed to a measuring circuit 5 upon putting them together as either in the positive direction or negative direction through the polarity inversion made by a polarity inverter circuit 6. The measuring circuit 5 has a measuring instrument 9 which measures the fed charging current and discharging current and determines the residual capacity of the secondary battery 1 through cumulation of the measurements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging / discharging current measuring method, a remaining power amount measuring method and a measuring device used for evaluating the remaining capacity of a power storage secondary battery. It is a thing.

[0002]

2. Description of the Related Art As a conventional charge / discharge current measuring device for a secondary battery for storing electric power of this type, a device having a structure as shown in FIG. 10 is known. That is, the secondary battery 21
At the time of charging or discharging, currents flowing in different directions in the charge / discharge circuit 22 are converted into voltages by the shunt resistor 23 and input to the measurement circuit 24. In the measuring circuit 24, the input voltage is measured by the voltage measuring device 26 in a state where the input voltage is insulation-converted into a predetermined measurement range by the insulation amplifier 25.

Then, the voltage measurement value of the voltage measuring device 26 is converted into a current measurement value by the arithmetic unit 27, and the current measurement value is integrated by the integrating unit 28 to obtain the remaining capacity of the secondary battery 21. . That is, the secondary battery 2
By setting the rated capacity of 1 as the initial value and integrating the charging current on the plus side and the discharging current on the minus side, the remaining capacity at each time point associated with the charging / discharging operation of the secondary battery 21 is calculated. To be evaluated.

[0004]

However, the conventional charge / discharge measuring device for a secondary battery has the following problems. (1) As shown by the chain line in FIG. 11, if there is an output error in the isolation amplifier 25, an error in current measurement between the charging side and the discharging side is added and generated, and those currents are integrated to calculate the remaining capacity from the difference. In the method of calculating, the evaluation error of the remaining capacity per charge / discharge becomes large. That is, the integrated value on the charge side is the one integrated on the plus side, and the integrated value on the discharge side is the one integrated on the minus side.
Since the absolute values are integrated on the plus and minus opposite sides, if the error values at the time of discharging and charging are the same, they will be doubled. As the number of times of charging / discharging increases, this error is accumulated and becomes larger. (2) Since one isolation amplifier 25 is configured to convert the currents in both positive and negative directions on the charging side and the discharging side, as shown in FIG. 8, the corresponding range L of the isolation amplifier 25 is wide, The inclination of the output curve C becomes smaller. Therefore, the rate of change of the output with respect to the fluctuation of the current becomes small,
Highly accurate measurement is not possible. (3) The voltage measuring device 26 used in the measuring circuit 24 is
Most of them have an input specification of 1 to 5 V, but the measured value on either the charge side or the discharge side becomes the low output side of the isolation amplifier 25, the output is not stable, and the measurement error of the voltage measuring device 26 growing. Therefore, the evaluation error of the residual capacity of the secondary battery 21 also increases.

The present invention has been made by paying attention to the problems existing in such conventional techniques. Its purpose is to enable accurate measurement and evaluation of the remaining capacity of the secondary battery with an inexpensive measurement circuit configuration without using a high-precision insulation amplifier, etc. It is to provide a measuring method and an apparatus thereof.

[0006]

[Means for Solving the Problems] In order to achieve the above object, in the invention of the charging / discharging current measuring method for a secondary battery for power storage according to claim 1, charging and discharging of the secondary battery are performed. The current flowing in different directions in the discharge circuit is unified into either the positive direction or the negative direction by polarity reversal and is input to the measurement circuit, and the charge and discharge currents are measured in the measurement circuit.

According to the second aspect of the invention, in the charging / discharging current measuring method for the secondary battery according to the first aspect, the current flowing in the charging / discharging circuit is converted into a voltage and input to the measuring circuit, and the voltage is Insulation amplifier is used for insulation conversion to measure.

Further, in the invention of claim 3, in the method for measuring the charging / discharging current of the secondary battery according to claim 1 or 2, the polarity is inverted according to the charging and discharging of the secondary battery by an external command. It is a thing.

Further, in the invention of claim 4, in the charging / discharging current measuring method for the secondary battery according to claim 1 or 2, the measured value of the measuring circuit is used to charge or discharge the secondary battery. The polarity is reversed.

In the invention of the charging / discharging current measuring device for a secondary battery for power storage according to claim 5, the currents flowing in different directions in the charging / discharging circuit at the time of charging and discharging the secondary battery are positive or A polarity reversing circuit for uniformly inputting to either one of the negative directions to the measuring circuit is provided between the charging / discharging circuit and the measuring circuit.

In addition, in the invention of the method for measuring the remaining power amount of the secondary battery for power storage according to claim 6, when charging and discharging the secondary battery, the currents flowing in different directions in the charge / discharge circuit are polarized. By reversing, input in either the positive direction or the negative direction to the measurement circuit, input the measurement circuit charge and discharge current, and measure the charging and discharging power from the current value and the battery voltage value during charging and discharging. Is calculated by summing up and, respectively, and the residual electric energy is measured by the difference.

Further, in the invention of the method for measuring the amount of remaining power of the secondary battery for power storage according to claim 7, when the secondary battery is charged and discharged, currents flowing in different directions in the charge / discharge circuit are reversed in polarity. Input to the measurement circuit in either the positive or negative direction, measure the charge and discharge currents in that measurement circuit, and measure the remaining capacity based on the current value. The remaining electric energy is measured based on

Further, in the invention of the method for measuring the remaining power amount of the secondary battery for power storage according to the eighth aspect, when the secondary battery is charged and discharged, currents flowing in different directions in the charge / discharge circuit are reversed in polarity. Input to the measurement circuit in either the positive direction or the negative direction, measure the charge and discharge currents in that measurement circuit, integrate the respective current values, and measure the remaining capacity based on the difference. Then, the depth of discharge is obtained from this, and the remaining electric energy is measured by estimating and calculating the discharge voltage and the discharge current after the depth of discharge based on the theoretical curve of the battery voltage.

[0014]

According to the first and fifth aspects of the present invention, when the secondary battery is charged and discharged, the currents flowing in different directions in the charge / discharge circuit are either in the positive direction or the negative direction due to the polarity inversion of the polarity inversion circuit. It is input to the measurement circuit as one unit. Then, in this measuring circuit, the input charging current and discharging current are measured, and the remaining capacity of the secondary battery is obtained by integrating the measured values with charging being positive and discharging being negative.

According to the second aspect of the present invention, even if the charging / discharging circuit has a high voltage, the insulation amplifier protects the measuring circuit and does not damage it, so that safe measurement is possible. In the inventions of claims 3 and 4, the polarity inversion can be automatically performed along with the switching of charging and discharging.

According to the sixth aspect of the present invention, the charging and discharging current values are measured, the charging power and the discharging power are integrated from the current value and the battery voltage value at the time of charging / discharging, and the remaining value is calculated based on the difference. Electric energy is measured.

In the seventh aspect of the present invention, the remaining capacity is measured based on the charging and discharging current values, and the remaining electric energy is measured based on the remaining capacity and the discharging voltage. Claim 8
In the invention, the charging and discharging current values are integrated, the remaining capacity is measured based on the difference, and the depth of discharge is obtained from this. Then, based on the theoretical curve of the battery voltage, the remaining voltage is measured by estimating the discharge voltage and the discharge current after the depth of discharge.

[0018]

EXAMPLES First Example A first example of a charging / discharging current measuring device for a secondary battery for power storage embodying the present invention will be described in detail below with reference to FIGS. 1 and 2.

As shown in FIG. 1, a secondary battery 1 for power storage.
Is connected to the charge / discharge circuit 2 and is composed of a module such as a sodium-sulfur battery. Although not shown, the module is composed of a plurality of blocks, the blocks are composed of a plurality of strings, and the strings are composed of a plurality of sodium-sulfur single cells. Then, by the switching control of the charging / discharging switching device 3, for example, during a predetermined time in the daytime, the secondary battery 1 is discharged and electric power is supplied from the charging / discharging circuit 2 to the power transmission line or the like via the AC / DC converter. During a predetermined time at night, the secondary battery 1 is charged and the charging / discharging circuit 2 charges the secondary battery 1.

The shunt resistor 4 is connected to the charging / discharging circuit 2, and when the secondary battery 1 is charged or discharged, currents flowing in different directions in the charging / discharging circuit 2 are converted into voltages by the shunt resistor 4 and measured. Input to 5.

The polarity reversing circuit 6 is interposed between the charging / discharging circuit 2 and the measuring circuit 5 and is composed of a plurality of relay switches. Then, when the secondary battery 1 is switched between the charging operation and the discharging operation by the charge / discharge switching device 3, an external command from the charge / discharge switching device 3 causes a polarity via the control device 7 including a sequencer or a CPU unit. The inverting circuit 6 is switched. As a result, as shown in FIG. 2, when charging and discharging the secondary battery 1, the currents flowing in different directions in the charging / discharging circuit 2 are either positive or negative in polarity reversal (in the embodiment, It is unified in the positive direction) and is input to the measurement circuit 5 in a state of being converted into a voltage.

The isolation amplifier 8 is connected to the measurement circuit 5, and the insulation amplifier 8 insulates and converts the input voltage of the measurement circuit 5 into a predetermined measurement range (1 to 5 V). The voltage measuring device 9 is connected to the output side of the isolation amplifier 8, and the voltage measuring device 9 measures the input voltage of the measuring circuit 5. The arithmetic device 10 is connected to the output side of the voltage measuring device 9, and the arithmetic device 10 converts the voltage measurement value of the voltage measuring device 9 into an absolute current value. At this time, by the control of the control device 7,
The absolute value of the current is switched between the positive direction and the negative direction of integration according to the conditions of charging and discharging. The integrator 11 is connected to the output side of the arithmetic unit 10, and the current value is integrated by the integrator 11. Then, if the rated capacity value of the secondary battery 1 is set at the end of charging in advance, the remaining capacity of the secondary battery 1 can be obtained by this integration.

Next, a method of measuring the charging / discharging current of the secondary battery in the charging / discharging measuring device for the secondary battery for power storage configured as described above will be described. During charging operation and discharging operation of the secondary battery 1, currents flowing in different directions in the charging / discharging circuit 2 are converted into voltages by the shunt resistor 4 and insulation conversion by the insulation amplifier 8, and the measurement circuit 5
Is input to The voltage between both electrodes of the charging / discharging circuit 2 of the secondary battery 1 is usually about 1000 V, and the isolation amplifier 8
Outputs 1 to 5 V from the secondary side in a state where insulation is secured from the charge / discharge circuit 2.

At this time, the polarity reversing circuit 6 is switched by the controller 7 in accordance with the switching of charging and discharging of the secondary battery 1 based on an external command from the charging / discharging switching device 3.
The polarity of the input voltage is inverted only in the positive direction and input to the measurement circuit 5.

Then, in the measuring circuit 5, the input voltage is measured by the voltage measuring device 9 in a state where the input voltage is insulation-converted into a predetermined measurement range by the insulation amplifier 8. After that, the absolute value of the current is obtained from the voltage measurement value of the voltage measuring device 9 by the calculation of the calculation device 10, and the absolute value of the current is controlled by the control device 7 to determine whether the integration is positive or negative according to the conditions of charging and discharging. The direction can be switched to the negative direction. Then, the integrating device 11 integrates the charging current into the plus side and the discharging current into the minus side, and evaluates the remaining capacity at each time point associated with the charging / discharging operation of the secondary battery 1.

As described above, in this embodiment, the polarity reversing circuit 6 reverses the polarity only in the positive direction while the charging and discharging currents flowing through the charging and discharging circuit 2 in different directions are converted into voltages. Is input to the measurement circuit 5. Therefore, as shown by the chain line in FIG. 2, even if there is an output error in the isolation amplifier 8, the current measurement error between the charging side and the discharging side is not added to the plus and minus opposite sides, but is offset. Therefore, when the remaining capacity is evaluated from the integrated value of these currents, the remaining capacity evaluation error can be reduced. Moreover, the switching for polarity reversal is automatically performed by the operation of the charging / discharging switching device 3 in conjunction with the switching of charging / discharging, and the switching timing is not missed so that the measurement result does not become an erroneous value.

Further, since the isolation amplifier 8 is adapted to convert the current only in the positive direction, the measurement range for measuring the current can be narrowed as shown in FIG. Therefore, the corresponding range L of the isolation amplifier 25 becomes narrow and the slope of the output curve C becomes large. Therefore, the rate of change of the output with respect to the fluctuation of the current becomes large, and measurement with high fluctuation accuracy becomes possible. In other words, it is not necessary to use an expensive isolation amplifier that exhibits a highly accurate function over a wide measurement range, and the measurement circuit 5 can be inexpensively configured.

Further, even when a voltage measuring device 9 having an input specification of 1 to 5 V is used, since the current is measured only in the positive direction by reversing the polarity, either the charging side or the discharging side is insulated. It is not performed on the low output side of the amplifier, the output of the isolation amplifier is stable, and the remaining capacity of the secondary battery 1 can be accurately measured and evaluated.

[0029]

[Other Embodiment] Another embodiment of the present invention will be described below. (Second Embodiment) First, in the second embodiment shown in FIGS. 3 and 4, the measured value of the voltage measuring device 9 is input to the control device 7. Further, the isolation amplifier 8 is provided with a function of slightly converting to the negative side, and when the voltage measuring device 9 measures a negative current more than a predetermined value, the control device 7 judges this and instantaneously activates the polarity reversing circuit 6. It is designed to switch to. Therefore, in this embodiment, the polarity of the charging / discharging current can be reversed according to the charging and discharging of the secondary battery 1 by self-determination based on the measurement value of the voltage measuring device 9. Therefore, also in the second embodiment, the polarity inversion can be automatically performed. (Third Embodiment) Next, in the third embodiment shown in FIGS. 5 and 6, a polarity determiner 12 for determining the voltage polarity is connected to the input side of the polarity inverting circuit 6. When the polarity determiner 12 detects a voltage equal to or higher than a predetermined value, the polarity reversing circuit 6 is switched by the identification threshold determination of the control device 7. That is, as shown in FIG.
The polarity determiner 12 outputs an output corresponding to the polarity and voltage of the charging / discharging circuit 2, and the controller 12 determines the polarity when the positive and negative outputs of the polarity determiner 12 exceed the threshold value. Therefore, also in this embodiment, the polarity inversion of the charge / discharge current can be automatically performed according to the charging and discharging of the secondary battery 1 by the self-determination based on the detection of the polarity determiner 12. Note that if this threshold value is set to about 5% or less of the rated current, a practically sufficient function can be obtained. (Fourth Embodiment) Next, in the fourth embodiment, the remaining electric energy is calculated by the following method and can be displayed. That is, the remaining power amount W ₁ (Wh) is calculated by the following equation (1).

W ₁ = ∫W _c (t) dt × η−∫W _d (t) dt (1) where W _c (t) is charging power and W _c (t) = V _c (t)
× I _c (t). V _c (t) is the charging voltage, I
_c (t) is the charging current. W _d (t) is discharge power,
_Wd (t) = _Vd (t) × _Id (t). V _d (t)
Is the discharge voltage, and I _d (t) is the discharge current. η represents charge / discharge efficiency.

This charging / discharging efficiency η may be one set value when the operating conditions are always the same, but when the operating conditions are different, the charging / discharging efficiency corresponding to the operating conditions can be automatically selected. It is desirable to do.

When the operating conditions are always the same, the efficiency η of each cycle is obtained by the following equation (2) and used as the efficiency η of the next cycle, so that the optimum evaluation can always be performed.

Η = (time average value of V _d (t)) / (time average value of V _c (t)) (2) Further, since Joule heat loss due to internal resistance of the battery is taken into consideration, The average internal resistance R _m of the cycle is calculated by the following equation (3).

R _m = (W _c −W _d ) / (∫I _C (t) ² dt + ∫I _d (t) ² dt) (3) where W _c is the charging power amount of one cycle, W _d is the discharge electric energy of one cycle, I _C (t) is the charging current (measured value), I
_d (t) is the discharge current (measured value).

Using R _m obtained by this evaluation, V _D can be corrected by the following equation (4). _{V D = V 0 -R m ×} I D ··· (4) where, V ₀ is the average discharge open voltage (set point), I _D is the rated discharge current (set value).

Alternatively, the average internal resistance R _m can be calculated by the following equation (5).
It can also be calculated by R _m ≈ (V _0e −V _de ) / I _de (5) where V _0e is the open circuit voltage after discharge, V _de is the battery voltage at the end of discharge, and I _de is the current value at the end of discharge. .

As described above, in this embodiment, the remaining electric energy (Wh) can be measured easily and accurately.
Moreover, since the remaining power amount can be displayed, the remaining capacity (Ah) cannot easily grasp the dischargeable time when discharging with constant power, whereas
It is possible to immediately know the dischargeable time with constant power. In addition, by evaluating the remaining power amount (Wh), not only the deterioration of the battery based on the remaining capacity (Ah) but also the deterioration of the battery can be determined in consideration of the change in the internal resistance R _m. Can be determined more accurately. (Fifth Embodiment) Next, a fifth embodiment of the present invention will be described with reference to FIGS.

In this example, the amount of remaining power was determined as follows from the remaining capacity (Ah) obtained in the first example. That is, the remaining electric energy W ₂ (Wh) is
It is calculated by the following equation (6).

W ₂ = remaining capacity (Ah) × V _D (6) However, V _D represents the initial setting value of the rated discharge voltage. This V
_It is desirable to correct _D by the internal resistance R _m described in the fourth embodiment. Further, when the discharge conditions are the same every cycle, it is also possible to directly obtain an appropriate V _D by the following equation (7).

V _D = W _D / ∫I _d (t) dt (7) V _D varies depending on the discharge power, and the residual power also varies accordingly. Therefore, as shown in FIG. 7A, the relationship between the discharge power (W) and the discharge voltage (V _D ) can be graphed,
As shown in FIG. 7 (b), it is desirable that the relationship between the two is also shown in a table so that the discharge voltage can be easily read from the discharge power and used for internal calculation.

Furthermore, as shown in FIG. 8 (a), the relationship between the discharge power (W) and the remaining power amount (Wh) is plotted in a graph, or as shown in FIG. It is desirable for the user to see at a glance the amount of remaining power corresponding to the discharge power by using the table below.

In addition, the discharge voltage (V _D ) is the depth of discharge (A
Since it also differs depending on h), more accurate evaluation can be made possible by expressing the discharge voltage as a function of the depth of discharge. FIG. 9 shows the relationship between the depth of the battery and the open circuit voltage. With V _D = V _D (q ₀ ), evaluation is performed in the depth region from the current depth (q ₀ ) to the end of discharge, and the residual power amount is evaluated using this V _D. V _D (q) is preset as an initial setting function, and there are a method of estimating it from test data and a method of giving it generally by a theoretical formula. In the case of the theoretical formula, the following procedure can be considered as an example. That is, in Example 1, the relationship between the depth and the open circuit voltage has already been theoretically shown, and since the open circuit voltage at that depth is already obtained when the discharge is once completed, the current depth reaches the end of the discharge. The average open-circuit voltage V _0D (q ₀ ) up to this point can be easily calculated.

The average open circuit voltage V _D (q ₀ ) from the current depth to the end of discharge can be evaluated by the following equation. The _{V D (q 0) = V} 0D (q 0) -R m × I d (q 0) The average internal resistance R _m of several of the aforementioned methods, it is also possible to use a correction value, I _d ( q ₀ ) is the measured current value at that depth. Instead of I _d (q ₀ ),
The rated discharge current I _D may be used, but it is considered that I _d (q ₀ ) is more accurate in a deeper region.
The current discharge depth is a value obtained by subtracting the remaining capacity (Ah) from the total capacity (Ah) of the battery.

As described above, in this embodiment, since the remaining electric energy (Wh) can be displayed, it is possible to easily grasp the dischargeable time by the constant electric power. Moreover,
By evaluating the remaining power amount (Wh), the internal resistance R
The deterioration of the battery can be accurately determined by considering the change in _m .

If higher accuracy is required, the following equation is considered effective. That is, if the rated discharge power is P _D , the following relationship is given. _{P D = (V 0D (q} ) -R m × I d (q)) × I d (q) where, q denotes the depth of discharge (q = q (t)) .

[0046]

[Equation 1]

[0047]

[Equation 2]

[0048]

(Equation 3)

However, te represents the dischargeable time from the current depth q ₀ . Therefore, it is possible to evaluate the remaining power amount with high accuracy by performing the arithmetic processing in a simulation from the time point of q = q ₀ (t = 0).

The present invention may be embodied by changing the configuration as follows, for example. (1) In the first embodiment, when there is no command for charging / discharging from the charging / discharging switching circuit 3 to the control device 7, it is determined that the secondary battery 1 is in a rest period during which charging / discharging operation is not performed. And stop charging and discharging current integration. With such a configuration, it is possible to prevent the error from accumulating due to the zero point fluctuation of the isolation amplifier during the idle period of the secondary battery 1, and the secondary battery 1
The remaining capacity of can be evaluated more accurately. (2) In the third embodiment, when the voltage detected by the polarity determiner 12 is equal to or lower than the predetermined threshold value as shown in FIG. 6, it is determined that the secondary battery 1 is in the idle period. , Configure to suspend the integration of charge / discharge current. In the case of such a configuration as well, it is possible to prevent the accumulation of errors due to the zero point variation and improve the evaluation accuracy of the remaining capacity. (3) In each of the above embodiments, the polarity reversing circuit 6 reverses the polarities of the charging current and the discharging current in the negative direction and inputs them to the measuring circuit 5.

Further, the technical idea grasped from the above embodiment will be described below. (A) When charging and discharging the secondary battery, the currents flowing in different directions in the charging / discharging circuit are unified into either the positive direction or the negative direction by polarity reversal and are input to the measuring circuit. A method for measuring the remaining capacity of a secondary battery for power storage, which measures a charging and discharging current and measures the remaining capacity based on the current value. According to this method, the remaining capacity can be accurately measured with a small evaluation error. (B) The residual power amount measuring method of the secondary battery for power storage according to claim 6 or 7, wherein the residual power amount can be displayed. With this configuration, it is possible to immediately understand the dischargeable time with constant power. (C) The residual power amount measuring method of the secondary battery for power storage according to claim 6 or 7, wherein the residual power amount is measured in consideration of the internal resistance of the battery. According to this configuration, it is possible to more accurately determine the deterioration of the battery.

[0052]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects. Claim 1
According to the invention of 5 and 5, when the secondary battery is charged and discharged,
Due to the polarity reversal of the polarity reversing circuit, the currents flowing through the charging / discharging circuit in different directions are uniformly input to the measuring circuit in either the positive direction or the negative direction. Then, in this measuring circuit, the input charging current and discharging current are measured, and the remaining capacity of the secondary battery is obtained by integrating the measured values with charging being positive and discharging being negative. Therefore, the remaining capacity of the secondary battery can be accurately measured and evaluated with an inexpensive measurement circuit configuration without using a high-precision insulating amplifier.

According to the second aspect of the present invention, even if the charge / discharge circuit has a high voltage, the measurement circuit is protected by the insulation amplifier and is not destroyed, so that the safe measurement can be performed. According to the third and fourth aspects of the present invention, the polarity inversion can be automatically performed along with the switching of charging and discharging.

According to the sixth and seventh aspects of the present invention, the amount of remaining power can be obtained easily and accurately, and the dischargeable time at constant power can be easily known from the amount of remaining power. Also, deterioration of the battery can be accurately determined.

According to the invention described in claim 8, the remaining electric energy can be evaluated with high accuracy.

[Brief description of drawings]

FIG. 1 is a block diagram of a charge / discharge measuring device according to a first embodiment.

FIG. 2 is a graph showing the relationship between voltage and current in a charge / discharge measuring device.

FIG. 3 is a block diagram of a charge / discharge measuring device according to a second embodiment.

FIG. 4 is a graph showing the relationship between voltage and current in a charge / discharge measuring device.

FIG. 5 is a block diagram of a charge / discharge measuring device according to a third embodiment.

FIG. 6 is a graph showing the relationship between measured voltage and current in another example.

FIG. 7A is a graph showing the relationship between discharge power and discharge voltage, and FIG. 7B is a tabular diagram showing the relationship between discharge power and discharge voltage.

FIG. 8A is a graph showing a relationship between discharge power and remaining power, and FIG. 8B is a tabular diagram showing a relationship between discharge power and remaining power.

FIG. 9 is a graph showing the relationship between the depth of discharge and the open circuit voltage.

FIG. 10 is a block diagram showing a conventional charge / discharge measuring device.

FIG. 11 is a graph showing the relationship between the voltage and current measured by the charge / discharge measuring device.

[Explanation of symbols]

1 ... Secondary battery, 2 ... Charge / discharge circuit, 3 ... Charge / discharge switching device,
4 ... Shunt resistance, 5 ... Measurement circuit, 6 ... Polarity inversion circuit,
7 ... Control device, 8 ... Insulation amplifier, 9 ... Voltage measuring device, 10
... arithmetic device, 11 ... integrating device.

Claims (8)

[Claims] 1. When charging and discharging a secondary battery, currents flowing in different directions in a charging / discharging circuit are unified into either a positive direction or a negative direction by polarity reversal and input to a measuring circuit, and the measurement is performed. A charging / discharging current measuring method for a secondary battery for power storage, which measures charging and discharging currents in a circuit. 2. The charging / discharging of the secondary battery for power storage according to claim 1, wherein the current flowing in the charging / discharging circuit is converted into a voltage, which is input to the measuring circuit, and the voltage is insulation-converted by an insulation amplifier for measurement. Current measurement method. 3. The charging / discharging current measuring method for a secondary battery for power storage according to claim 1, wherein polarity reversal is performed according to charging and discharging of the secondary battery in accordance with an external command. 4. The charge / discharge current measuring method for a secondary battery for power storage according to claim 1, wherein polarity reversal is performed according to charging and discharging of the secondary battery based on a measurement value of a measuring circuit. 5. A polarity reversing circuit for unifying the currents flowing in different directions in the charge / discharge circuit at the time of charging and discharging the secondary battery in either the positive direction or the negative direction into the measurement circuit, A charging / discharging current measuring device for a secondary battery for storing power, which is interposed between a charging / discharging circuit and a measuring circuit. 6. When charging and discharging a secondary battery, the currents flowing in different directions in the charge / discharge circuit are unified into either the positive direction or the negative direction by polarity reversal and input to the measurement circuit, and the measurement is performed. A secondary battery for power storage that measures charging and discharging currents in a circuit, calculates charging current and discharging power from the current value and battery voltage value during charging / discharging respectively, and measures the remaining power amount by the difference. Method for measuring the amount of remaining electric power. 7. When charging and discharging a secondary battery, currents flowing in different directions in a charge / discharge circuit are unified into either a positive direction or a negative direction by polarity reversal and are input to a measurement circuit, and the measurement is performed. A method for measuring the remaining power amount of a secondary battery for power storage, which measures the charge and discharge currents in a circuit, measures the remaining capacity based on the current value, and measures the remaining power amount based on the remaining capacity and the discharge voltage. . 8. When charging and discharging a secondary battery, currents flowing in different directions in a charge / discharge circuit are unified into either a positive direction or a negative direction by polarity reversal and are input to a measurement circuit, and the measurement is performed. Measure the charging and discharging current in the circuit, integrate each of those current values, measure the remaining capacity based on the difference, calculate the depth of discharge from this, based on the theoretical curve of the battery voltage A method for measuring the remaining power amount of a secondary battery for power storage, which measures the remaining power amount by estimating and calculating a discharge voltage and a discharge current.