JP2001091604A - Remaining capacity detection device for power storage device - Google Patents

Abstract

(57) [Problem] To provide a remaining capacity detection device for a power storage device with improved detection accuracy of the remaining capacity. SOLUTION: A battery control device 5 samples a current and a voltage of a battery 1 at a predetermined timing at a predetermined interval until reaching a preset sampling number.
If the amount of change in the sampled battery current is large, the open circuit voltage of the battery 1 is estimated from the sampled battery current and battery voltage, and
The remaining capacity corresponding to the detected open-circuit voltage is detected from the remaining capacity-open-circuit voltage characteristic. On the other hand, when the amount of change in the sampled battery current is small, the remaining current of the battery 1 is detected by integrating the sampled current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the remaining capacity of a power storage device.

[0002]

2. Description of the Related Art Hitherto, a hybrid vehicle equipped with a motor in addition to an engine as a driving source for running the vehicle has been known. As one type of this hybrid vehicle, there is a parallel hybrid vehicle using a motor as an auxiliary drive source for assisting the output of the engine. This parallel hybrid vehicle performs various controls such as assisting the output of the engine by the motor during acceleration and charging the battery by deceleration regeneration during deceleration to secure the remaining capacity of the battery. While satisfying the driver's requirements.

As a method of detecting the remaining capacity of the battery, there is a method of calculating the remaining capacity by integrating the battery current. This is a method of detecting a battery current at a predetermined timing, and integrating this value to detect a remaining capacity. However, if the accuracy of the current sensor for detecting the battery current is low, an error occurs in the detected current value.
As described above, in the present method, the remaining capacity of the battery is obtained by integrating this current value, so that the error is integrated together with the current value, and as a result, the calculated remaining capacity value becomes A large error will be included. As described above, in calculating the remaining capacity by current integration, an error occurs in the calculated value of the remaining capacity, so that the detection accuracy of the remaining capacity is poor.

In addition to the above-described method of detecting the remaining battery charge by current integration, there is a method of detecting the remaining battery charge from the open voltage of the battery. Specifically, a plurality of battery currents and battery voltages are sampled at predetermined intervals,
Based on these sampling data, battery current =
The battery voltage at the time of 0, that is, the open circuit voltage is obtained. Then, the remaining capacity corresponding to the above-mentioned open-circuit voltage is detected from the remaining capacity-open-circuit voltage characteristic unique to the battery. The remaining capacity detection method has an advantage that the remaining capacity detection accuracy is higher than the remaining capacity detection by current integration described above.

[0005]

However, the above-described method for detecting the remaining battery charge from the open-circuit voltage of the battery involves the following:
In a period in which the amount of change in the battery current is large, for example, in a period of time T1 to T2 and T3 to T4 in FIG. 7, the open circuit voltage can be accurately detected, and can be effectively used for detecting the remaining capacity. On the other hand, during a period when the battery current is constant, for example, during a period from time T2 to T3 in FIG. 7, it is difficult to estimate the open-circuit voltage, and it is impossible to detect the remaining capacity. As a result, there is a problem that the remaining capacity cannot be detected during the period when the battery current is constant. The present invention has been made in view of such circumstances,
An object of the present invention is to provide a remaining capacity detection device of a power storage device with improved detection accuracy of the remaining capacity.

[0006]

In order to achieve the above object, the present invention relates to a method for controlling the current (in the embodiment, battery current Ibat) of a power storage device (in the embodiment, battery 1).
t), voltage (in the embodiment, battery voltage Vbatt)
(In the embodiment, step S1) for sampling at a predetermined interval, current of the power storage device sampled by the sampling means,
An open-circuit voltage estimating unit (in the embodiment, step S4) for estimating an open-circuit voltage (in the embodiment, the open-circuit voltage OCV of the battery 1) from the voltage, and the open-circuit voltage estimated by the open-circuit voltage estimating unit. A first remaining capacity detecting means (in the embodiment, step S5) for detecting a remaining capacity of the power storage device from a second power source, and a second remaining capacity for detecting the remaining capacity of the power storage device by integrating the sampled current. Detecting means (step S10 in the embodiment) and a case where the current change of the power storage device sampled by the sampling means is greater than or equal to a first reference value (in the embodiment, the current change amount is 0.5 ( In the case where the ratio M of the sampling number P smaller than A) to the total sampling number n is 50% or less), the first remaining capacity detecting means is selected. In the case where the current change of the power storage device is smaller than the first reference value (in the embodiment, the sampling number P in which the current change amount is smaller than 0.5 (A) is larger than the total sampling number n) The occupying ratio M is 5
(In the case of being larger than 0%), selecting means for selecting the second remaining capacity detecting means (in the embodiment, step S6)
And characterized in that:

As described above, in an area where the amount of change in the battery current is small and it is impossible to estimate the open voltage from the sampling data of the battery voltage and the battery current, the first remaining capacity detection that detects the remaining capacity based on the open voltage is performed. From the means
The remaining capacity detection means is switched to the second remaining capacity detection means for detecting the remaining capacity by current integration. Thereby, the remaining capacity is detected by the appropriate remaining capacity detecting means in accordance with the amount of change in the battery current, so that the accuracy of detecting the remaining capacity of the power storage device can be improved.

Further, according to the invention described in claim 2, the current of the power storage device (the battery 1 in the embodiment) is
Sampling means for sampling the battery current Ibatt) and the voltage (battery voltage Vbatt in the embodiment) at predetermined intervals (step S1 in the embodiment)
An open-circuit voltage estimating unit for estimating an open-circuit voltage (open-circuit voltage OCV of the battery 1 in the embodiment) of the power storage device from a current and a voltage of the power storage device sampled by the sampling unit; Remaining capacity detection means for detecting the remaining capacity of the power storage device from the open circuit voltage estimated by
5) The remaining capacity detection device for a power storage device, further comprising: when the open voltage estimated last time is present, the open voltage estimating means is configured to sample the open voltage estimated last time and the open voltage. The open circuit voltage of the power storage device is estimated from the current and the voltage of the power storage device (in the embodiment,
Steps S7 and S8).

As described above, by adding the open circuit voltage used for detecting the remaining capacity of the power storage device to the sampling data last time, it is possible to estimate the open circuit voltage even in a region where the change in the battery current is small. The value of the remaining capacity corresponding to the estimated open-circuit voltage can be detected from a graph of the remaining capacity-open-circuit voltage characteristic. This allows
Since the remaining capacity is detected by the appropriate remaining capacity detecting means in accordance with the amount of change in the battery current, the accuracy of detecting the remaining capacity of the power storage device can be improved.

[0010] Further, according to the invention of claim 3, the current of the power storage device (the battery 1 in the embodiment) (in the embodiment,
Sampling means for sampling the battery current Ibatt) and the voltage (battery voltage Vbatt in the embodiment) at predetermined intervals (step S1 in the embodiment)
And the change in current of the power storage device sampled by the sampling means is equal to or greater than a first reference value (in the embodiment, the number of samplings P in which the amount of change in current is smaller than 0.5 (A) is equal to the total number of samplings n Is less than or equal to 20%), the current of the power storage device sampled by the sampling means,
First open-circuit voltage estimating means for estimating the open-circuit voltage of the power storage device from the voltage (step S4 in the embodiment); and the open-circuit voltage of the power storage device estimated from the open-circuit voltage estimated by the first open-circuit voltage estimating device. First remaining capacity detection means (step S5 in the embodiment) for detecting the remaining capacity, and a change in the current of the power storage device less than the first reference value (in the embodiment, the change in the current is 0.5 ( A) The ratio M of the sampling number P smaller than the total sampling number n
Is larger than the second reference value (in the embodiment, the ratio M of the sampling number P in which the current variation is smaller than 0.5 (A)) to the total sampling number n. Is less than or equal to 50%), a second open-circuit voltage estimating means for estimating the open-circuit voltage from the current and voltage of the power storage device sampled by the sampling means and the open-circuit voltage estimated last time ( In the embodiment,
Steps S7 and S8), third remaining capacity detection means (in the embodiment, step S9) for detecting the remaining capacity of the power storage device from the open voltage estimated by the second open voltage estimation means, The change in the current of the power storage device sampled by the sampling means is less than the second reference value (in the embodiment, the sampling number P in which the current change amount is smaller than 0.5 (A) becomes the total sampling number n). A second remaining capacity detection means for integrating the current of the power storage device sampled by the sampling means and detecting the remaining capacity of the power storage device when the ratio M of the power storage device to the power storage device is larger than 50%. (Step S10 in the embodiment).

As described above, since the remaining capacity is detected by the appropriate remaining capacity detecting means in accordance with the change in the current of the power storage device, the accuracy of detecting the remaining capacity of the power storage device can be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment adapted for a parallel hybrid vehicle. In this figure, reference numeral 1 denotes a high-voltage battery, which is configured by connecting a plurality of cells in series, and further connecting a plurality of modules in series. Reference numeral 2 denotes a power drive unit, which is configured by connecting two switching elements in series and three in parallel.

Reference numeral 3 denotes an engine operated by the combustion energy of fuel, and reference numeral 4 denotes a motor used in combination with the engine 3 and operated by electric energy. The driving force of both the engine 3 and the motor 4 is transmitted to driving wheels (not shown) via a transmission (not shown) composed of an automatic transmission or a manual transmission. When the hybrid vehicle is decelerated, the driving force is transmitted from the driving wheels to the motor 4, and the motor 4 functions as a generator to generate a so-called regenerative braking force and charge the battery 1. It should be noted that a configuration may be adopted in which a generator for charging the battery 1 is provided separately from the driving motor 4.

The drive and regeneration of the motor 4 are controlled by the power drive unit 2 in response to a control command from the motor controller 6.
It is performed by Specifically, when the switching element inside the power drive unit 2 is turned on and off by the motor control device 6, the electric power from the battery 1 is supplied to the motor 2 via the three-phase line, or Regenerative power is supplied to the battery 1.

Reference numeral 5 denotes a battery control device which detects a battery voltage Vbatt, a battery current Ibatt, and a battery temperature Tbatt at predetermined timings, and detects the remaining capacity SOC of the battery 1 from these values.

Reference numeral 7 denotes an engine control device, which monitors the engine speed NE, the vehicle speed, and the like at predetermined intervals to determine a mode such as motor regeneration, assist, and deceleration.
At the same time, the engine control device 7 determines the result of the above-described mode determination and the remaining capacity S transmitted from the battery control device 5.
The assist / regeneration amount is determined from the OC. The battery control device 5, the motor control device 6, the engine control device 7
Is constituted by a CPU (Central Processing Unit) and a memory, and realizes the functions by executing a program for realizing the functions of the control device.

Reference numeral 8 denotes a noise cut filter, which is installed near a voltage sensor for detecting the voltage of the battery 1 and a current sensor for detecting the current of the battery 1. External noise can be cut by the noise cut filter 8, whereby the above-described voltage sensor and current sensor can detect accurate voltage and current.

Next, the first embodiment of the present invention having the above-described configuration will be described.
FIG. 4 shows detection of remaining capacity of battery 1 according to the embodiment.
This will be described in detail with reference to FIG. It is assumed that all the processes described below are performed by the battery control device 5.

First, in step S1 in FIG. 4, the battery control device 5 in FIG.
t, battery current Ibatt, battery temperature Tbatt
Are sampled n times at predetermined intervals. Here, the sampling number n is a value preset in the battery control device 5 and can be arbitrarily determined. Next, the battery control device 5 controls the battery voltage Vbatt and the battery current Ibat.
When the sampling data of t and the battery temperature Tbatt reaches the arbitrarily set sampling number n, the process proceeds to step S2.

In step S2, the number P of sampling data whose change in detected battery current Ibatt is 0.5 (A) or less is extracted. Specifically, the Nth (N: an arbitrary integer) detected battery current Ibat
The battery current Ibatt detected at (N-1) th from t
Is extracted, the number P of sampling data whose current difference is within 0.5 (A) is extracted.

Next, in step S3, the ratio M of the sampling data number P having a small current change amount to the entire sampling number n is calculated, and it is determined whether or not the calculated value is larger than the second reference value. . Specifically, it is determined by the following equation. M = (P / n) * 100> 20 (%) (1)

In the equation (1), P indicates that the amount of change in the battery current Ibatt detected in step S2 is 0.
5 (A) or less. N is the number of samplings set in advance in step S1. Then, the number of sampling data P detected in step S2 is changed to the total number of samplings n.
, The ratio M of the sampling data number P having the small current change amount ΔI to the entire sampling number n, that is, the current value stability M is calculated.

The greater the value of the current value stability M, the smaller the amount of change over time of the battery current Ibatt. When the value of the current value stability M thus calculated is equal to or smaller than 20 (%) of the second reference value, that is, when the time change amount of the battery current Ibatt is relatively large, step The process proceeds to S4, and if the value of the current value stability M is larger than 20 (%), that is, if the amount of change in the battery current Ibatt is relatively small, the process proceeds to step S6.

In step S4, the battery current Ibatt detected in step S1 and the battery voltage Vbatt are detected.
Is plotted on a current-voltage graph. That is, the battery current Ibatt detected at the same time and the battery voltage Vbat
With t as a set of coordinates, (Ibatt, Vbatt) is plotted on a current-voltage characteristic graph (see FIG. 2) with the X-axis as battery current Ibatt and the Y-axis as battery voltage Vbatt.

When plotting is completed for all sampling data, an asymptote B of the plotted coordinates is obtained.
And the point at which this asymptote B contacts the Y axis, that is, the value E0 of the Y intercept, is detected. The value E0 of the Y-intercept means the value of the battery voltage Vbatt at the battery current Ibatt = 0, that is, the open-circuit voltage OCV of the battery 1. Thus, the Y intercept of the asymptote B is detected as the open circuit voltage OCV.

Next, at step S5, the remaining capacity SOC corresponding to the open-circuit voltage OCV detected at step S4.
Is detected from the remaining capacity-open circuit voltage characteristic. FIG. 5 shows a remaining capacity-open-circuit voltage characteristic of the battery 1. In this figure,
The X axis is the remaining capacity SOC, and the unit is (%). The Y-axis is the open circuit voltage OCV, and the unit is (V). Then, engine control device 5 determines remaining capacity SOC corresponding to open-circuit voltage OCV detected in step S4.
Is detected from the graph shown in FIG.

Since the remaining capacity-open-circuit voltage characteristic varies depending on the temperature of the battery 1, the battery control device 5
Stores the remaining capacity-open-circuit voltage characteristic at each temperature. Then, the remaining capacity-open-circuit voltage characteristic corresponding to the battery temperature Tbatt detected in step S1 is selected.

When the state of charge SOC is detected in step S5, the battery control unit 5
C is output to the motor control device 6. Then, the detected remaining capacity SOC of the battery 1 is referred to by each control device as one of important parameters for controlling the hybrid vehicle.

On the other hand, if the current value stability M is larger than 20 (%) in step S3, the process proceeds to step S3.
Move to 6. In step S6, it is further determined whether or not the above-described current value stability M is greater than 50 (%). If the current value stability M is equal to or less than 50 (%), the process proceeds to step S7. If the current value stability M is greater than 50 (%), the process proceeds to step S10.

In step S7, similarly to the processing in step S4, the battery current Ibat detected in step S1 is detected.
t, a process of plotting the battery voltage Vbatt in a current-voltage graph is performed. At this time, in step S7, the value of the open circuit voltage OCV used for the previous remaining capacity detection is added as one of the sampling data to the data of the battery current Ibatt and the battery voltage Vbatt detected in step S1.

When plotting is completed for all the sampling data, the process proceeds to step S8, where the asymptote B of the coordinates plotted in step S7 is obtained, and the point at which this asymptote B contacts the Y axis, ie, the value of the Y intercept, E0 is detected. Note that the value E0 of the Y intercept is a value slightly different from the value of the open circuit voltage SOC used in the previous detection of the remaining capacity. This is because the asymptote B was newly obtained from the previous open-circuit voltage SOC and the sampling data detected this time. Then, the point at which the newly obtained asymptote touches the Y axis, that is, the Y intercept E0 is detected as the current open circuit voltage OCV.

Then, in step S9, the remaining capacity SOC corresponding to the open circuit voltage OCV detected in step S8.
Is detected from the remaining capacity-open-circuit voltage characteristic of the battery 1 shown in FIG. 5, similarly to the processing of step S5 described above.

On the other hand, if the current value stability M is larger than 50 (%) in step S6,
Move to 10. In step S9, the remaining capacity ΔSOC per unit time is calculated by integrating the battery current Ibatt detected in step S1, and this value is multiplied by the temperature coefficient α. The temperature coefficient α is drawn, for example, by a curve as shown in FIG. 6, and when the temperature exceeds a predetermined temperature, the value of the temperature coefficient α becomes constant. Accordingly, a corresponding temperature coefficient α is determined from the battery temperature Tbatt detected in step S1, and the value is multiplied by the remaining capacity per unit time ΔSOC determined above.

Further, a value obtained by multiplying the remaining capacity per unit time ΔSOC by a temperature coefficient α corresponding to the remaining capacity SOC of the battery 1 detected last time is added. Thus, the current remaining capacity of the battery 1 is calculated. The case where the remaining capacity is detected by current integration is when sampling data as shown in FIG. 3 is obtained, for example. In FIG. 3, the value of the battery current Ibatt hardly changes. In such a current-voltage plot, the asymptote becomes infinite, so that the value of the Y intercept, that is, the value of the open circuit voltage OCV, cannot be detected from the asymptote.

In such a case, the remaining capacity is detected by current integration as described above. Note that, in the present embodiment, if the current value stability M becomes a value larger than 50 (%), FIG.
Is set as described above, and the remaining capacity detection by current integration is performed.

As described above, by changing the method of detecting the remaining capacity SOC according to the value of the current value stability M, it is possible to select the detection method most suitable for the state of the current change. This makes it possible to detect an accurate remaining capacity with the least error.

Next, when the vehicle is stopped and the battery current Ib
The detection of the remaining capacity of the battery 1 when no att is flowing will be described. First, just like when the vehicle is running,
The battery control device 5 determines the battery current Ibatt, the battery voltage Vbatt, and the battery temperature T at a predetermined timing.
Detect batt. However, while the vehicle is stopped, the value of the battery current Ibatt becomes zero. Therefore, the detected battery voltage Vbatt is the open circuit voltage OCV.
The battery control device 5 calculates the battery voltage Vbatt,
That is, the remaining capacity SOC corresponding to the open-circuit voltage OCV is detected from the remaining capacity-open-circuit voltage characteristic shown in FIG. 5, and the remaining capacity is determined.

As described above, when the vehicle is stopped, the battery current Ibatt indicates zero, so that the remaining capacity SOC can be determined from the battery voltage Vbatt detected at the same time. Even when the vehicle is not stopped, the remaining capacity can be detected in the same manner even when the state where the battery current Ibatt is zero continues for a predetermined period or more.

Next, transitions of the battery voltage Vbatt and the battery current Ibatt corresponding to the state of the vehicle are shown in FIG. In this figure, at time 0 to T1, the vehicle is stopped.
The vehicle is running from T4 to T4, and the vehicle is stopped after time T4. In each state of such a vehicle, first, when the vehicle is stopped, that is, after time 0 to T1 and time T4, the battery current Ibatt indicates zero and the battery voltage Vba
tt is constant. Therefore, the battery voltage Vbatt
= Open circuit voltage OCV, and the battery control device 5
The remaining capacity can be easily detected from the remaining capacity-open-circuit voltage characteristic of the battery 1 shown in FIG.

Next, a period during which the vehicle is running and the time variation of the battery current Ibatt is large, that is, from time T1 to time T1.
During the periods T2 and T3 to T4, the battery control device 5
Can determine the open circuit voltage OCV from a plurality of sampled battery currents Ibatt and battery voltage Vbatt. Then, when the open circuit voltage OCV is obtained, FIG.
The remaining capacity SOC corresponding to the open-circuit voltage OCV is detected from the remaining capacity-open-circuit voltage characteristic of the battery 1 shown in FIG. 4 (steps S4 and S5 in FIG. 4).

On the other hand, during the period from time T2 to time T3, the battery current Ibatt is constant and the amount of change is small. That is, the battery current Ibatt and the battery voltage Vbatt sampled by the battery control device 5 are as shown in FIG. 3, for example. Thus, the battery current I
When the batt is constant, the asymptote of the current-voltage characteristic becomes parallel to the Y axis, so that the Y intercept E0, that is,
The open circuit voltage OCV cannot be detected. In such a case, the battery control device 5 calculates the remaining capacity SOC of the battery 1 by integrating currents (step S10 in FIG. 4).

It should be noted that the battery current Ibatt changes at time T2.
In the case where the current value stability M is not constant as shown by T3 and slightly fluctuates, that is, when the current value stability M is larger than 20 (%) and equal to or smaller than 50 (%), FIG. As shown in steps S7 to S9, the remaining capacity SOC is detected by obtaining the current open voltage OCV by adding the value of the open circuit voltage OCV previously used for detecting the remaining capacity of the battery 1 to the sampling data.

In the above-described embodiment, the change in the battery current Ibatt is determined based on the time change ΔI. However, the change width of the battery current Ibatt may be used as the reference for determining the current change. . In particular,
The rate at which the change width of the battery current Ibatt is close to a predetermined value, or the rate of change of the battery voltage Ibatt, by arbitrarily setting the change width of the current and changing the range from the set lower reference value to the upper limit reference value, or May be determined based on the width of the minimum value and the maximum value of the current data sampled within the time period.

[0044]

As described above, according to the apparatus for detecting the remaining capacity of the power storage device according to the present invention, when the amount of change in the current of the power storage device is equal to or greater than the first reference value, the current and voltage of the power storage device are plotted. And the remaining capacity corresponding to the open-circuit voltage is obtained from the remaining capacity-open-circuit voltage characteristic. on the other hand,
When the amount of change in the current of the power storage device is smaller than the first reference value, the remaining capacity of the battery is calculated by current integration.

As described above, the remaining capacity is detected by current integration only in a region where the amount of change in the current of the power storage device is small and the open-circuit voltage cannot be estimated from the current and voltage sampling data of the power storage device. Accordingly, the remaining capacity is detected by the appropriate remaining capacity detection unit in accordance with the amount of change in the current of the power storage device, so that the accuracy of detecting the remaining capacity of the power storage device can be improved.

According to the second aspect of the invention, the open-circuit voltage used when the remaining capacity of the power storage device was detected last time is added to the sampled current and voltage values of the power storage device, and the values are released from these values. Detect voltage. Then, the remaining capacity corresponding to the detected open-circuit voltage is detected from the remaining capacity-open-circuit voltage characteristic. Accordingly, even when the current change of the power storage device is small, the remaining capacity can be detected from the open circuit voltage, and the detection accuracy of the remaining capacity can be further improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a hybrid vehicle.

FIG. 2 is a diagram showing current-voltage characteristics of a battery during running of a vehicle.

FIG. 3 is a diagram showing current-voltage characteristics of a battery during running of a vehicle.

FIG. 4 is a flowchart illustrating a process performed by a remaining capacity detection device according to an embodiment of the present invention.

FIG. 5 is a diagram showing a remaining capacity-open-circuit voltage characteristic of the battery 1 in FIG.

FIG. 6 is a diagram showing a transition of a temperature coefficient of the battery 1 in FIG.

FIG. 7 is a diagram showing changes in battery voltage and battery current in each state of the vehicle.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 battery 5 battery control device 6 motor control device 7 engine control device S1 sampling means S3, S6 selection means S4, S8 open-circuit voltage estimation means S5 first remaining capacity detection means S10 second remaining capacity detection means

Continued on the front page F term (reference) 2G016 CA03 CB11 CB12 CB13 CB21 CB22 CB31 CB32 CC01 CC04 CC27 5G003 AA07 BA01 DA07 EA05 FA06 GC05 5H030 AA08 AS08 FF42 FF44 5H115 PG04 PI16 PO17 PU01 PU25 QE10 TI05 SE12

Claims (3)

[Claims] A sampling means for sampling a current and a voltage of the power storage device at predetermined intervals; and an open-circuit voltage estimation for estimating an open-circuit voltage of the power storage device from a current and a voltage of the power storage device sampled by the sampling means. Means, first remaining capacity detection means for detecting the remaining capacity of the power storage device from the open-circuit voltage estimated by the open-circuit voltage estimation means, and integrating the sampled current to obtain the remaining capacity of the power storage device. A second remaining capacity detecting means for detecting, when the current change of the power storage device sampled by the sampling means is equal to or greater than a first reference value, selecting the first remaining capacity detecting means, And selecting means for selecting the second remaining capacity detection means when the current change of the power storage device is smaller than the first reference value. The remaining capacity detection device of the power storage device. 2. Sampling means for sampling the current and voltage of the power storage device at predetermined intervals, and open-circuit voltage estimation for estimating the open-circuit voltage of the power storage device from the current and voltage of the power storage device sampled by the sampling means. Means for detecting the remaining capacity of the power storage device from the open-circuit voltage estimated by the open-circuit voltage estimating means, and a remaining capacity detection device for the power storage device, further comprising: The means, when the previously estimated open circuit voltage is present, estimates the open circuit voltage of the power storage device from the previously estimated open circuit voltage and the sampled current and voltage of the power storage device. Power storage device remaining capacity detection device. 3. Sampling means for sampling the current and voltage of the power storage device at predetermined intervals, and when the change in current of the power storage device sampled by the sampling means is equal to or greater than a first reference value, the sampling is performed. First open-circuit voltage estimating means for estimating the open-circuit voltage of the power storage device from the current and voltage of the power storage device sampled by the means; and the open-circuit voltage estimated by the first open-circuit voltage estimating device, First remaining capacity detection means for detecting the remaining capacity of the power storage device, and when the current change of the power storage device is less than the first reference value and greater than or equal to the second reference value, the sampling means Second open-circuit voltage estimating means for estimating the open-circuit voltage from the sampled current and voltage of the power storage device and the open-circuit voltage estimated last time; A third remaining capacity detecting means for detecting a remaining capacity of the power storage device from the open voltage estimated by the second open voltage estimating means; and a change in current of the power storage device sampled by the sampling means, And a second remaining capacity detecting means for detecting the remaining capacity of the power storage device by integrating the current of the power storage device sampled by the sampling means when the value is less than a second reference value. An apparatus for detecting a remaining capacity of a power storage device.