JP2015040764A - Battery charge rate detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery charging rate detection device which, when obtaining a final charging rate by weighting a first charging rate obtained by a current integration method and a second charging rate obtained by an open-circuit voltage estimation method, can detect the charging rate of a battery with high accuracy by taking even a slow response speed portion of the battery into account.SOLUTION: A battery charging rate detection device comprises: first charging rate calculation means 4 for calculating a first charging rate by integrating charge/discharge currents; second charging rate calculation means 5 for estimating an open-circuit voltage of the battery from the charge/discharge currents, a terminal voltage detected by voltage detection means, and an impedance of an equivalent circuit of the battery, and calculating a second charging rate on the basis of the estimated open-circuit voltage; and third charging rate calculation means 6 for combining the first charging rate and the second charging rate after weighting these charging rates using a weight set in accordance with a response speed determined by a charging-rate region in which a previous charging rate exists, and calculating a third charging rate of the battery.

Description

  The present invention relates to a battery charge rate detection device capable of accurately detecting a charge rate of a secondary battery.

As a conventional battery charge rate detection device, the one described in Patent Document 1 is known.
This conventional battery charge rate detection device uses a battery charge rate (SOC: State of Charge) obtained by integrating the charge / discharge current of the battery and a charge rate obtained from an estimated value of the battery open voltage. The charging capacity corresponding to the final charging rate of the battery is obtained by weighting and synthesizing with weights that change as needed according to the situation.

JP 2005-201743 A

However, the conventional battery charge rate detection device has the following problems.
That is, in the above-described conventional battery charge rate detection device, a response (slow response) at a slow speed of the battery appears, and due to this, the accuracy of the charge rate has deteriorated. However, since the above calculation is performed as it is, there is a problem that the actual characteristics of the battery cannot be reflected and the calculated charging rate is deteriorated.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to use the charging rate obtained based on the integrated charging / discharging current and the charging rate obtained based on the open circuit voltage. When the final charge rate is obtained by weighting the battery, the battery charge rate detection device can detect the battery charge rate with higher accuracy in consideration of the slow response speed part of the battery. Is to provide.

For this purpose, the battery charge rate detection device according to the present invention comprises:
Current detection means for detecting the charge / discharge current of the battery;
Voltage detection means for detecting the terminal voltage of the battery;
First charge rate calculation means for calculating the first charge rate by integrating the charge / discharge current detected by the current detection means;
A battery open-circuit voltage is estimated from the charge / discharge current detected by the current detection means, the terminal voltage detected by the voltage detection means, and the impedance of the battery equivalent circuit, and the second charge rate is calculated based on the estimated open-circuit voltage. 2 charging rate calculation means;
The first charging rate obtained by the first charging rate calculating means and the second charging rate obtained by the second charging rate calculating means are set according to the response speed determined by the area of the charging rate where the previous charging rate exists. A third charging rate calculating means for calculating a third charging rate of the battery by weighting and combining using the weights obtained;
It is provided with.

Preferably, the third charging rate calculation means increases the weight of the first charging rate as the time until the terminal voltage of the battery becomes stable is longer.
It is characterized by that.

Preferably, the third charging rate calculation means increases the weight of the first charging rate in proportion to the time taken for the terminal voltage to stabilize.
It is characterized by that.

Preferably, the range in which the first weight is increased is determined based on the material of the positive electrode of the battery in the region where the previous charging rate is high, and is determined based on the material of the negative electrode of the battery in the region where the previous charging rate is low.
It is characterized by that.

Preferably, the battery is a battery using lithium manganate as a positive electrode,
When the third charging rate calculating means is in the charging rate region where the response rate of the previous charging rate is 50 to 80% becomes slow, the weight of the first charging rate is increased.
It is characterized by that.

Preferably, the battery is a battery using graphite as a negative electrode,
When the third charging rate calculation means is in the charging rate region where the response rate of the previous charging rate is 10 to 40% is slow, the weight of the first charging rate is increased.
It is characterized by that.

Preferably, the battery is a battery using lithium manganate for the positive electrode and graphite for the negative electrode,
The third charging rate calculation means is configured to increase the weight of the first charging rate when the previous charging rate is in the range of 65 to 80% and 30 to 40%.
It is characterized by that.

Preferably, the battery is a battery using nickel-based material for the positive electrode and graphite for the negative electrode,
The third charging rate calculation means increases the weight of the first charging rate when the previous charging rate is in the range of 50 to 80% and 10 to 30%.
It is characterized by that.

Preferably, the battery is a battery using lithium manganate for the positive electrode and lithium titanate for the negative electrode,
When the third charging rate calculation means is in the region where the previous charging rate is 50 to 70%, the weight of the first charging rate is increased.
It is characterized by that.

  In the battery charge rate detection device of the present invention, the battery charge rate can be detected with higher accuracy in consideration of the slow response speed portion of the battery.

  In addition, since the third charging rate calculation means increases the weight of the first charging rate as the time until the terminal voltage of the battery stabilizes, the influence of the slow response speed portion of the battery is minimized. It can be made smaller.

  In addition, since the third charging rate calculation means increases the weight of the first charging rate in proportion to the time required for the terminal voltage to stabilize, the third charging rate calculation means is adapted to the influence of the slow response speed portion of the battery. Therefore, it is possible to detect a charging rate with high accuracy.

  In addition, the range in which the first weight is increased is determined based on the material of the positive electrode of the battery in the region where the charging rate is high, and is determined based on the material of the negative electrode of the battery in the region where the charging rate is low. It becomes possible to detect the charging rate with high accuracy according to the material of the electrode.

  In addition, when the battery is a battery using lithium manganate as the positive electrode, and the third charging rate calculation means is in a charging rate region where the response rate of the previous charging rate is 50 to 80% is slow, Since the weight of the charging rate of 1 is increased, even when the battery is used, it is possible to detect the charging rate with high accuracy according to the material of the battery pole.

  Further, when the battery is a battery using graphite as a negative electrode, and the third charging rate calculation means is in a charging rate region where the response rate of the previous charging rate is 10 to 40% is slow, the first charging rate is Since the charging rate weight is increased, it is possible to detect a highly accurate charging rate.

  Further, the battery is a battery using lithium manganate for the positive electrode and graphite for the negative electrode, and the third charging rate calculation means is in a region where the previous charging rate is 65 to 80% and 30 to 40%. At this time, since the weight of the first charging rate is increased, it is possible to detect the charging rate with high accuracy.

  Further, the battery is a battery using a nickel-based material for the positive electrode and graphite for the negative electrode, and the third charging rate calculation means is in a region where the previous charging rate is 50 to 80% and 10 to 30%. At this time, since the weight of the first charging rate is increased, it is possible to detect the charging rate with high accuracy.

  Further, when the battery is a battery using lithium manganate for the positive electrode and lithium titanate for the negative electrode, and the third charge rate calculating means is in the region where the previous charge rate is 50 to 70%, Since the weight of the charging rate of 1 is increased, it is possible to detect a highly accurate charging rate.

It is a block diagram which shows the structure of the charging rate detection apparatus of the battery which concerns on Example 1 of this invention. It is a figure which shows the flowchart of the charging rate detection process performed in the charging rate determination part of the charging rate detection apparatus of a battery. (a) is the figure which represented the relationship between the charging rate of a battery-an open circuit voltage for every elapsed time, (b) is a figure which shows the relationship between a charging rate and a weight. It is a block diagram which shows the structure of the charge rate determination part which comprises the charge rate detection apparatus of the battery which concerns on Example 2 of this invention. (a) is a figure which shows the relationship between a charging rate and a voltage difference according to elapsed time, (b) is a figure which shows the relationship between a charging rate and a 1st weight. The figure which compared and showed the experimental result of the charging rate by the true value of a charging rate, the charging rate by a prior art, and the charging rate by Example 2 about the relationship between a travel distance and a charging rate when the charging rate is in a range of 60-80%. It is. The figure which compared and showed the experimental result of the charging rate by the true value of a charging rate, the charging rate by a prior art, and the charging rate by Example 2 about the relationship between a travel distance and a charging rate when the charging rate is in a range of 20 to 50% It is. It is a figure which shows the relationship of the charging rate-open circuit voltage for every different elapsed time in the battery which respectively used the nickel type for the positive electrode and the graphite for the negative electrode. It is a figure which shows the relationship of the difference of a charging rate-terminal voltage and an open circuit voltage for every different elapsed time in the battery which respectively used the nickel-type acid for the positive electrode, and the graphite for the negative electrode. It is a figure which shows the relationship of the charging rate-open circuit voltage for every different elapsed time in the battery which respectively used the lithium manganate for the positive electrode and the lithium titanate for the negative electrode. It is a figure which shows the relationship of the difference of the charging rate-terminal voltage open voltage and open voltage for every different elapsed time in the battery which respectively used the lithium manganate for the positive electrode and the lithium titanate for the negative electrode.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
In the following embodiments, substantially the same parts are denoted by the same reference numerals, and the omission thereof may be described.

First, the overall configuration of the battery charge rate detection apparatus according to the first embodiment will be described.
The battery charge rate detection apparatus according to the first embodiment is mounted on an electric vehicle or a hybrid vehicle.
That is, as shown in FIG. 1, the charging rate detection device is connected to a battery 1 that is also mounted on the vehicle, and is connected to a charging / discharging current detection unit 2, a terminal voltage detection unit 3, a current integration method charging rate estimation unit 4, and an open circuit. A voltage estimation method charging rate estimation unit 5, a charging rate determination unit 6, and a previous value holding unit 7 are provided.

  The battery 1 is a secondary battery that can be charged and discharged, and has a large number of cells connected in series. Although a lithium ion battery is used here, the present invention is not limited to this, and other types of batteries may be used.

The charge / discharge current detection unit 2 detects the charge / discharge current that flows when the battery 1 is charged and when the battery 1 is discharged, and corresponds to the current detection means of the present invention.
The terminal voltage detection unit 3 detects the terminal voltage of the battery 1 and corresponds to the voltage detection means of the present invention.

The current integration method charging rate estimator 4 performs a calculation by a current integration method (also referred to as a coulomb count method). That is, the charge / discharge current detected by the charge / discharge current detector 2 is integrated to obtain the amount of change in charge, and the value obtained by dividing by the full charge is added to the initial charge rate to calculate the first charge rate SOC1. This is input to the charging rate determination unit 6.
The current integration method charging rate estimation unit 4 corresponds to the first calculation means of the present invention.

The open-circuit voltage estimation method charging rate estimation unit 5 performs calculation by the open-circuit voltage estimation method. That is, the battery 1 has an equivalent circuit model (not shown) and a Kalman filter, and the charge / discharge current detected by the charge / discharge current detection unit 2 and the terminal voltage detected by the terminal voltage detection unit 3 are input and based on these. Thus, the open circuit voltage (OCV) of the battery 1 is estimated. In addition, it has relational data of the open circuit voltage (OCV) -charge rate (SOC) of the battery 1 obtained by measuring in advance, and based on the relation data, the charge rate corresponding to the estimated open circuit voltage is 2 is calculated as a charging rate SOC2 and is input to the charging rate determination unit 6.
The open-circuit voltage estimation method charging rate estimation unit 5 corresponds to a second calculation means.

The charging rate determination unit 6 receives the first charging rate SOC1 calculated by the current integration method charging rate estimation unit 4 and the second charging rate SOC2 calculated by the open circuit voltage estimation method charging rate estimation unit 5, The previous value SOC3 (k−1) of the third charging rate SOC3 calculated last time by the charging rate determination unit 6 and held by the previous setting holding unit 7 is input.
Here, k represents the current time (however, discrete time), so k-1 represents the previous sampling time.
The charging rate determination unit 6 performs weighting synthesis by multiplying the first charging rate SOC1 and the second charging rate SOC2 by weights described later according to the value of the previous position SOC (k−1), The third charging rate SOC3 is calculated and output.
The charging rate determination unit 6 corresponds to the third calculation means of the present invention.

  The previous value holding unit 7 stores the third charging rate SOC3 (k) output from the charging rate determination unit 6, and this value is stored in the previous third charging rate SOC3 ( Since it is used as k-1), this previous value can be input to the charging rate determination unit 6. Note that z in the block indicates z conversion.

The charging rate determination unit 6 executes a charging rate determination process according to the flowchart shown in FIG.
The charging rate determination unit 6 reads the previous value SOC3 (k−1) of the third charging rate SOC3 from the previous position holding unit 7 in step S1. Next, the process proceeds to step S2.
In step S2, whether or not the previous value SOC3 (k-1) read is in the range of 60% <SOC3 (k-1) <80% or 20% <SOC3 (k-1) <50% is determined. judge.
If this determination is YES, the process proceeds to step S3, and if NO, the process proceeds to step S4.

Here, it is determined whether or not the previous value SOC3 (k-1) is within the above range because the instability of the battery 1 increases within the above range, in other words, whether the terminal voltage of the battery 1 has settled for a long time. Because there is no. As a result, in the above range, the response range that can be estimated by the Kalman filter is limited. Therefore, the open-circuit voltage method cannot obtain a highly accurate charging rate SOC2.
The reason why the terminal voltage does not settle for a long time as described above is that the battery 1 has a voltage change due to a slow response portion (long time constant).

In general, the spinel-type lithium manganate that is the positive electrode of the battery 1 is reduced from a tetravalent to a trivalent manganese as the lithium is inserted from the charged state (lithium ion desorption state), and the crystal lattice is reduced as this reduction occurs. Instability increases, and the crystal lattice transitions when the SOC is in the range of 60 to 80%. For this reason, nonlinearity appears in the electrode potential.
On the other hand, when the charge rate SOC is in the range of 20 to 50%, lithium ions are desorbed and inserted in the graphite, which is the negative electrode of the battery 1, and the stage structure in the battery 1 changes. For this reason, nonlinearity appears in the electrode potential.

In step S3, the first charging rate SOC1 is multiplied by a weight having a value of 1, and the second charging rate SOC2 is multiplied by a weight having a value of 0 to obtain a third charging rate SOC3. Therefore, in this case, SOC3 = SOC1.
On the other hand, in step S4, the first charging rate SOC1 is multiplied by a weight of value 0, and the second charging rate SOC2 is multiplied by a weight of value 1 to obtain the third charging rate SOC3. Therefore, in this case, SOC3 = SOC2.

FIG. 3 shows such weighting. In other words, as shown in the characteristic diagram of charge rate vs. open-circuit voltage in Fig. 5A, when the previous third charge rate is in the range of 20-30%, 60-80%, it is calculated by the current integration method. The first charging rate SOC1 is the third charging rate SOC3, and in the other regions, the second charging rate SOC2 calculated by the open-circuit voltage method is the third charging rate SOC3.
Here, the weight α multiplied by the second charging rate SOC2 and the previous third charging rate SOC3 (k−1) (however, simply indicated as SOC in the same drawing) in FIG. The relationship is shown.

The weight α (drawn with a thick solid line in FIG. 3B) is a weight multiplied by the first charging rate SOC1. That is, in this embodiment, the weight α is set to 1 or 0 according to the previous third charging rate SOC3 (k−1).
On the other hand, the second charging rate SOC2 is multiplied by a weight of 0 or 1, which is the reverse of the above.
Note that the one-dot chain line shown in the figure is a weight that is closer to the actual value, but the weight of the thick solid line is a binary value of 1 and 0, but approximates the value fairly well.

As a result, when the previous third charging rate SOC3 (k-1) is within the above range, the first charging rate SOC1 is multiplied by the weight 1, and the second charging rate SOC2 is 0. Will be multiplied.
On the other hand, when the previous third charging rate SOC3 (k-1) is outside the above range, the first charging rate SOC1 is multiplied by a weight 0, and the second charging rate SOC2 is 1 Will be multiplied.
The third charging rate is an added value of the first and second charging rates SOC1 and SOC2 in consideration of the weights.

The effect | action of the charging rate detection apparatus of Example 1 is demonstrated below.
The charging / discharging current detection unit 2 detects the charging / discharging current of the battery 1, and inputs this detection signal to the current integration method charging rate estimation unit 4 and the open circuit voltage estimation method charging rate estimation unit 5.
The terminal voltage detection unit 3 detects the terminal voltage of the battery 1 and inputs this detection signal to the open-circuit voltage estimation method charging rate estimation unit 5.

The current integration method charging rate estimation unit 4 calculates the first charging rate SOC1 of the battery 1 based on the value obtained by integrating the input charging / discharging current, and inputs this to the charging rate determination unit 6.
At the same time, the open-circuit voltage estimation method charging rate estimation unit 5 calculates the second charging rate SOC2 based on the input charging / discharging current and the terminal voltage, and inputs this to the charging rate determination unit 6.

Here, the charging rate determination unit 6 calculates the previous value SOC3 (k−1) of the third charging rate calculated last time and stored in the previous value holding unit 7, the first charging rate SOC1, and the second charging rate. SOC2 is input, and it is determined whether or not the previous position SOC3 (k-1) of the previous third charging rate is in the range of 20 to 50% or in the range of 60 to 80%. Here, being in the above range corresponds to the time required for the terminal voltage of the battery 1 being equal to or longer than a predetermined value until the terminal voltage of the battery 1 is stabilized.
On the other hand, if it is outside the above range, the weight is set to 1, so that the first charging rate SOC1 is multiplied by 0, and the second charging rate SOC2 is multiplied by 1. Therefore, in this case, the third charging rate SOC3 becomes the second charging rate SOC2.

On the other hand, if it is within the above range, the weight is set to 0, so the first charging rate SOC1 is multiplied by the weight of value 1, and the second charging rate SOC2 is multiplied by the weight of value 0. . Therefore, in this case, the third charging rate SOC3 becomes the first charging rate SOC1.
As a result, in the part where the influence of the part where the reaction speed of the battery 1 is slow is large, the second charging rate SOC2 obtained by the open-circuit voltage estimation method which deteriorates the accuracy is not used, and the current integration method which is not affected by the second charging rate SOC2 is obtained. By using the first charging rate SOC1, deterioration of the charging rate estimation accuracy is suppressed.

As can be seen from the above description, the battery 1 charging rate detection device of the first embodiment can obtain the following effects.
That is, in the charging rate detection device for battery 1, when the charging rate SOC is in the range of about 20 to 50% and in the range of about 60 to 80%, the first charging rate SOC1 calculated by the current integration method is used. The weight value is set to 1 and the weight value of the second charging rate SOC2 calculated by the open-circuit voltage method is set to 0, and the weight α is set according to the response speed of the battery 1 determined by the charging rate region. That is, in the region where the response speed is slow, the second charging rate SOC2 calculated by the open-circuit voltage method is not used.
Therefore, it is possible to calculate the final charge rate of the battery 1, that is, the third charge rate SOC3 in consideration of the slow response speed portion of the battery 1, and as a result, charge with higher accuracy than in the case of the prior art. Can detect the rate

  In addition, since the weight is binary, 0 and 1, it is possible to calculate a highly accurate charging rate with a simple calculation.

Next, a battery charge rate detection apparatus according to a second embodiment of the present invention will be described with reference to the drawings.
The battery charge rate detection device according to the second embodiment includes the functional blocks having the same configuration as the battery charge rate detection device according to the first embodiment illustrated in FIG. 1, but the specific configuration of the charge rate determination unit 6 is as follows. This is different from the case of the first embodiment.

That is, in the second embodiment, as shown in FIG. 4, the charging rate determination unit 6 includes a first weight setting unit 6a, a first multiplier 6b, an adder 6c, a second weight setting unit 6d, 2 multiplier 6e.
The first weight setting unit 6a stores the relationship data of the charging rate-first weight, and the previous third charging rate SOC3 (k-1) held by the previous value holding unit 7 is inputted. Is determined based on the above data and input to the first multiplier 6b.
Note that the relationship data of the charging rate-first weight will be described later.

  The first multiplier 6b receives the first weight α determined by the first weight setting unit 6a and the first charging rate SOC1 calculated by the current integration method charging rate estimation unit 4 and multiplies them. The multiplication value is input to the adder 6c.

The second weight setting unit 6d stores the charging rate-second weight relationship data, and the previous third charging rate SOC3 (k-1) held by the previous value holding unit 7 is input. Is determined based on the above data and input to the second multiplier 6e.
Note that the relation data of the charging rate-second weight will be described later.

  The second multiplier 6e receives the second charging rate SOC2 calculated by the open-circuit voltage estimation method charging rate estimation unit 5 and the second weight β set by the second weight setting unit 6d, and multiplies them. Then, this multiplication value is input to the adder 6c.

The adder 6c adds the multiplication value obtained by the first multiplier 6b and the multiplication value obtained by the second multiplier 6e, and outputs this addition value as the third charging rate SOC3.
Other configurations are the same as those of the first embodiment, and the description thereof is omitted.

Here, the values of the first weight α and the second weight β will be described.
FIG. 5A shows the relationship between the charging rate of the battery 1 and the voltage difference, and shows the characteristics for each elapsed time after the flow of the charging / discharging current of the battery 1 is stopped. Here, the potential difference is a voltage difference between the open voltage when the battery 1 is stabilized and the open voltage at a different elapsed time.
In the figure, the solid line indicates that 3 hours have elapsed, the alternate long and short dash line indicates that 1 hour has elapsed, the broken line indicates that 10 minutes have elapsed, and the alternate long and two short dashes line indicates that 1 minute has elapsed. The shorter the elapsed time, the more the influence of the slower response portion of the battery 1 appears. That is, it can be seen that the open circuit voltage estimation method in a short time causes an estimation error in the open circuit voltage.

Therefore, as shown in FIG. 5B, the second charge rate calculated by the open-circuit voltage estimation method is set such that the value of the first weight α increases as the influence of the slow response portion of the battery 1 increases. The value of the second weight β of SOC2 is made small.
Note that since the added value of the first weight α and the second weight β is set to be always 1, the second weight β is a value obtained by subtracting the first weight α from 1. Therefore, as shown in FIG. 4, the graph of the second weight β has a shape obtained by inverting the figure (b) in the vertical direction.

The effect | action of the charging rate detection apparatus of Example 2 is demonstrated below.
The current integration method charging rate estimation unit 4 calculates the first charging rate SOC1, the open-circuit voltage estimation method charging rate estimation unit 5 calculates the second charging rate SOC2, and these calculated values are used as the charging rate determination unit 6 The signal flow and processing until the signal is input to are the same as those in the first embodiment.

The charging rate determination unit 6 receives the previous third charging rate SOC3 (k-1) stored in the previous value holding unit 7, and based on this value, the first weight setting unit 6a and the second weight The setting unit 6d determines the corresponding first weight α and second weight β, respectively.
The first weight α determined by the first weight setting unit 6a is input to the first multiplier 6b, multiplied by the first charging rate SOC1, and the second weight determined by the second weight setting unit 6d. β is input to the second divider 6e and multiplied by the second charging rate SOC2.

These division values are added by the adder 6b to become the third charging rate SOC3 (k).
That is, SOC3 = α · SOC1 + β · SOC2. Note that α + β = 1.
Here, when the third charging rate SOC3 (k-1) of the previous time is in the range of 20 to 50%, or 60 to 80%, the 1 weight setting unit 6a sets the first weight α to the second value. The weight is made larger than β, and when it is out of the range, the tendency is reversed.

  In other words, when the time taken for the terminal voltage of the battery 1 to stabilize is long, the first weight multiplied by the first charging rate is increased. In the second embodiment, the first weight α is increased in proportion to the time required for the terminal voltage to stabilize. The second weight β tends to be opposite to the above.

Fig. 6 and Fig. 7 show the results of experiments comparing the accuracy of the charge rate when the previous third charge rate SOC3 (k-1) is in the range of 60-80% or 20-50%. Indicates. In either case, the horizontal axis represents the travel time (seconds), and the vertical axis represents the charging rate (%).
In both the above figures, the true value is a solid line, the charging rate in the prior art is indicated by a one-dot chain line, and the charging rate in the charging rate detection device of Example 2 is indicated by a broken line.
In FIG. 6 showing the range of 60 to 80%, the detection accuracy of the charging rate is deteriorated in the case of the prior art in the range of about 2,500 seconds to about 3,500 seconds, but in the case of Example 2, it is extremely true. It can be seen that close values are obtained.
On the other hand, in FIG. 7 representing the range of 20 to 50%, the true value is obtained in the example 2 after about 19,700 seconds, although the deviation from the true value is large in the prior art. It can be seen that a value very close to is obtained.

As described above, the charging rate detection device for the battery 1 according to the second embodiment can obtain the following effects.
That is, in the charge rate detection device for the battery 1 of the second embodiment, the battery 3 in which the previous third charge rate SOC3 (k-1) is in the range of 60 to 80%, or in the range of 20 to 50%. In the region where the time taken for the terminal voltage to stabilize becomes long, the first weight α of the first charging rate SOC1 is increased in proportion to the time, and the second weight β of the second charging rate SOC2 is set to α. The third charging rate SOC3 is a value obtained by adding weights so as to have an opposite tendency (β = 1−α).
Therefore, it is possible to accurately detect the charging rate SOC3 of the battery 1 regardless of the presence of the slow response speed portion of the battery 1. This accuracy is better than that of the first embodiment.

As described above, the first embodiment and the second embodiment have been described. However, since an experiment was performed with respect to a range in which the response speed becomes slow according to the type of the battery, these examples will be described below.
In the present invention, the range in which the first weight in the region with a high charging rate is increased is determined based on the material of the positive electrode of the battery, and the range in which the first weight in the region with a low charging rate is increased. Is determined based on the material of the negative electrode of the battery. By doing in this way, it becomes possible to calculate a highly accurate charging rate.

As a result of the experiment, preferred embodiments are as follows.
In the case of a battery using lithium manganate as the positive electrode, the weight of the first charge rate is increased when the previous charge rate is in the charge rate region where the response speed is near 50 to 80%. .
Further, in the case of a battery using graphite as the negative electrode, the weight of the first charging rate is increased when the previous charging rate is in the charging rate region where the response speed is in the vicinity of 10 to 40%.
In addition, in the case of a battery using lithium manganate for the positive electrode and graphite for the negative electrode, when the previous charging rate is in the region of the charging rate where the response speed is slow in the vicinity of 65-80% and in the vicinity of 30-40%, The weight of the first charging rate is increased.
Also, in the case of a battery using a nickel-based material for the positive electrode and graphite for the negative electrode, when the previous charge rate is in the charge rate region where the response speed is slow in the vicinity of 50 to 80 and in the vicinity of 10 to 30%, 1 is to increase the weight of the charging rate.
Further, in the case of a battery using lithium manganate for the positive electrode and lithium titanate for the negative electrode, the first charge is performed when the previous charge rate is in the charge rate region where the response speed is near 50 to 70%. Increasing the weight of the rate.

  Here, among the above experimental examples, in the case of a battery using a nickel-based material for the positive electrode and graphite for the negative electrode, the relationship between the charging rate (SOC) and the open circuit voltage (OCV) for each different elapsed time, and FIG. 8 and FIG. 9 show the relationship between the charging rate (SOC) −the difference between the terminal voltage and the open circuit voltage (that is, the terminal voltage when stabilized such as after 24 hours) for each elapsed time with different terminal voltages.

Here, the elapsed time is 1 minute later, 10 minutes later, 30 minutes later, 1 hour later, 3 hours later, 24 hours later, and the straight line, the dotted line, the broken line, the one-dot chain line, and the two points in the figure, respectively. It is indicated by a chain line and a bold line.
As can be seen from FIG. 8, it can be seen that the open-circuit voltage changes depending on the amount of elapsed time. It is known that the open circuit voltage approaches the terminal voltage as the elapsed time becomes longer.
On the other hand, as shown in FIG. 9, the response rate is slow in the region where the charging rate is in the vicinity of 50 to 80% and 10 to 30%, and the charging rate obtained by the open-circuit voltage method in this region is a short elapsed time. Then, it turns out that accuracy deteriorates.

  Next, in the case of a battery using lithium manganate for the positive electrode and lithium titanate for the negative electrode, the relationship between the charging rate (SOC) and the open circuit voltage (OCV) for each different elapsed time, and the elapsed time with different terminal voltages The relationship between the difference between the charging rate (SOC) -terminal voltage and the open circuit voltage is shown in FIGS. 10 and 11, respectively.

Here, the elapsed time is taken after 1 minute, 10 minutes, 1 hour, 3 hours, and 24 hours, and is indicated by a straight line, a dotted line, a one-dot chain line, a two-dot chain line, and a thick line in the figure, respectively. Yes (however, in FIG. 11, it is omitted after 24 hours).
As can be seen from FIG. 10, it can be seen that the open circuit voltage changes depending on the amount of elapsed time. It is known that the open circuit voltage approaches the terminal voltage as the elapsed time becomes longer.
On the other hand, when FIG. 11 is seen, the response speed in the vicinity of 60% of the charging rate is slow, and it can be seen that the charging rate obtained by the open-circuit voltage method in this region becomes inaccurate in a short elapsed time.

  As described above, the present invention has been described based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and even if there is a design change or the like without departing from the gist of the present invention, the present invention is included.

  For example, the weighting may be performed when the charge / discharge current is large, such as when charging with an external power source, traveling on an uphill road, or traveling at high speed. In this case, a great effect can be obtained.

  Further, the third charging rate calculation means may increase the weight of the first charging rate when the charge / discharge current value becomes a predetermined value or more.

1 battery
2 Charge / discharge current detector (charge / discharge current detector)
3 Terminal voltage detector (terminal voltage detector)
4 Current integration method charging rate estimator (first calculation means)
5 Open-circuit voltage estimation method Charging rate estimator (second calculation means)
6 Charging rate determination unit (third calculation means)
6a First weight setting section
6b First multiplier
6c Second weight setting section
6d second multiplier
6e adder
7 Previous value holding section

Claims (9)

Current detection means for detecting the charge / discharge current of the battery;
Voltage detecting means for detecting a terminal voltage of the battery;
First charge rate calculating means for calculating a first charge rate by integrating charge / discharge currents detected by the current detection means;
The open circuit voltage of the battery is estimated from the charge / discharge current detected by the current detection unit, the terminal voltage detected by the voltage detection unit, and the impedance of the equivalent circuit of the battery, and the second charge rate is calculated based on the estimated open circuit voltage Second charging rate calculating means for
The first charging rate obtained by the first charging rate calculating unit and the second charging rate obtained by the second charging rate calculating unit are set according to a response speed determined by a region of the charging rate where the previous charging rate exists. A third charging rate calculating means for calculating a third charging rate of the battery by weighting and combining using the weight set in
A battery charge rate detection device comprising: The battery charge rate detection device according to claim 1,
The third charging rate calculation means increases the weight of the first charging rate as the time until the terminal voltage of the battery becomes stable is longer.
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The third charging rate calculation means increases the weight of the first charging rate in proportion to the time taken for the terminal voltage to stabilize.
What is claimed is: 1. A battery charge rate detection apparatus comprising: The battery charge rate detection device according to any one of claims 1 to 3,
The range in which the first weight is increased is determined based on the material of the positive electrode of the battery in the region where the previous charging rate is high, and is determined based on the material of the negative electrode of the battery in the region where the previous charging rate is low. To
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The battery is a battery using lithium manganate as a positive electrode,
The third charging rate calculation means is configured to increase the weight of the first charging rate when the previous charging rate is in a charging rate region where a response speed of 50 to 80% is slow.
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The battery is a battery using graphite as a negative electrode,
The third charging rate calculating means is configured to increase the weight of the first charging rate when the previous charging rate is in the charging rate region where the response speed is slowed by 10 to 40%.
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The battery is a battery using lithium manganate for the positive electrode and graphite for the negative electrode,
The third charging rate calculation means is configured to increase the weight of the first charging rate when the previous charging rate is in the range of 65 to 80% and 30 to 40%.
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The battery is a battery using nickel-based material for the positive electrode and graphite for the negative electrode,
The third charging rate calculation means increases the weight of the first charging rate when the previous charging rate is in a range of 50 to 80% and 10 to 30%.
What is claimed is: 1. A battery charge rate detection apparatus comprising: In the battery charge rate detection device according to claim 1 or 2,
The battery is a battery using lithium manganate for the positive electrode and lithium titanate for the negative electrode,
The third charging rate calculation means increases the weight of the first charging rate when the previous charging rate is in a range of 50 to 70%.
What is claimed is: 1. A battery charge rate detection apparatus comprising:

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