JP2020155312A - Device and method for controlling secondary battery - Google Patents

Abstract

To provide a device and a method for controlling a secondary battery, which can suppress the deterioration of a battery capacity of the secondary battery.SOLUTION: The secondary battery control device includes: a battery temperature acquisition unit 42 which acquires the battery temperature of a battery 10; a battery capacity calculation unit 43 which applies the acquired battery temperature to the relation (temperature-battery capacity model 51) between a preset battery temperature and an actual battery capacity which is a chargeable battery capacity of the battery 10 at the above preset battery temperature, to thereby acquire an actual battery capacity corresponding to the battery temperature; and an SOC width calculation unit 45 which calculates an actual SOC width in a manner to make a rated SOC width, which is specified relative to the rated battery capacity of the battery 10, correspond to the actual battery capacity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a secondary battery control device and a secondary battery control method applied to an alkaline secondary battery.

Nickel-metal hydride secondary batteries are used as in-vehicle power sources for electric vehicles and hybrid vehicles because of their high energy density.
For such a secondary battery, a technique for calculating a charge state (SOC: System of Charge) and controlling charge / discharge according to the battery temperature has been proposed (see, for example, Patent Document 1).

The apparatus described in Patent Document 1 accurately estimates the battery temperature without time delay and controls charging / discharging based on the estimation. The hybrid ECU of this device has a step of calculating the SOC of the secondary battery (battery), a step of calculating the initial WIN (charging side limited power) and the initial WOUT (discharge side limited power), and the outside temperature and battery temperature. The program is executed, which includes a step of detecting the current value of the secondary battery and a step of detecting the current value of the secondary battery. Further, in this hybrid ECU, a step of calculating the estimated battery temperature, a step of calculating the output limit ratio using the higher temperature of the estimated battery temperature and the detected battery temperature, and a step of calculating the output limit ratio, and the final WIN and the final WIN using the output limit ratio. Execute the program, including the step of calculating the final WOUT.

Japanese Unexamined Patent Publication No. 2006-101674

In recent years, since the battery capacity of a secondary battery has increased and the usage environment has expanded, it is desired to set a wide usage range that can be charged and discharged. On the other hand, if the range of use is set wide, there is a risk that the battery capacity of the secondary battery will decrease faster due to continued use of the battery or an increase in battery temperature.

The present invention has been made in view of such circumstances, and an object of the present invention is a control device for a secondary battery capable of suppressing a decrease in the battery capacity of the secondary battery, and a method for controlling the secondary battery. Is to provide.

The secondary battery control device for solving the above problems includes a battery temperature acquisition unit that acquires the battery temperature of the alkaline secondary battery, and the acquired battery temperature at the predetermined battery temperature and the battery temperature. By applying the relationship with the actual battery capacity, which is the rechargeable battery capacity of the secondary battery, the actual battery capacity acquisition unit that acquires the actual battery capacity corresponding to the battery temperature, and the rating of the alkaline secondary battery. It is provided with a usage range calculation unit that calculates the actual usage range so that the rated usage range determined for the battery capacity corresponds to the actual battery capacity.

A method for controlling a secondary battery that solves the above problems includes a battery temperature acquisition step of acquiring the battery temperature of an alkaline secondary battery, and the acquired battery temperature at a predetermined battery temperature and the battery temperature. The actual battery capacity acquisition step of acquiring the actual battery capacity corresponding to the battery temperature and the rating of the alkaline secondary battery by applying to the relationship with the actual battery capacity which is the rechargeable battery capacity of the secondary battery. It includes a usage range calculation step for calculating the actual usage range so that the rated usage range determined for the battery capacity corresponds to the actual battery capacity.

Secondary batteries are used within the rated usage range determined based on the rated battery capacity in order to suppress deterioration, but since the actual usable range narrows depending on the usage environment and temperature, use within the rated usage range. Even if you do, the deterioration may be accelerated. In this regard, according to such a configuration or method, the usage range corresponding to the battery capacity that changes according to the battery temperature is calculated as the actual usage range, and the charge / discharge of the secondary battery is controlled with respect to the actual usage range. It becomes possible to do. As a result, it is possible to suppress a decrease in the battery capacity of the secondary battery.

As a preferable configuration, when the battery temperature is higher than a predetermined temperature, the usage range calculation unit outputs the actual usage range calculated by the usage range calculation unit, and when the battery temperature is equal to or lower than the predetermined temperature. , The rated usage range is output.

According to such a configuration, whether the use range used for control is the rated use range or the actual use range is appropriately selected depending on the battery temperature at which the battery capacity is changed.
As a preferable configuration, a charging state calculation unit for calculating the value of the rated charging state with respect to the rated battery capacity and calculating the value of the actual charging state with respect to the actual battery capacity from the calculated value of the rated charging state is further provided.

As a preferred method, a charge state calculation step of calculating the value of the rated charge state with respect to the rated battery capacity and calculating the value of the actual charge state with respect to the actual battery capacity from the calculated value of the rated charge state is further provided.

According to such a configuration or method, a charged state with respect to the rated battery capacity and a charged state with respect to the actual battery capacity can be obtained. As a result, the charge / discharge of the secondary battery can be controlled based on the actual charge state obtained from the rated charge state of the secondary battery.

As a preferable configuration, a charge / discharge control unit for controlling charging / discharging of the alkaline secondary battery so as to be performed within the practical use range is further provided.
According to such a configuration, the deterioration of the secondary battery is suppressed by charging and discharging the secondary battery within the range of actual use.

As a preferable configuration, the actual charge state calculated by the charge state calculation unit is stored, the charge amount for each charging opportunity is acquired based on the actual charge state, and the frequency distribution of the acquired charge amount is set as the frequency. The capacity reduction speed is acquired by applying it to the relationship between the distribution and the capacity reduction speed, and when the acquired capacity reduction speed becomes larger than the switching threshold value, the output usage range is narrowed to the rated usage range.

As a preferred method, the actual charging state calculated by the charging state calculation step is stored, the charging amount for each charging opportunity is acquired based on the actual charging state, and the frequency distribution of the acquired charging amount for each charging opportunity. Is applied to the relationship between the frequency distribution and the capacity reduction rate to acquire the capacity reduction speed, and when the acquired capacity reduction speed becomes larger than the switching threshold value, the output usage range is set from the rated usage range. Narrow it.

Since the actual usage range of a deteriorated secondary battery is narrowed, if the usage is continued based on the rated usage range, the actual battery state will gather on the side relatively close to the upper limit of the actual usage range, and the capacity reduction rate will decrease. It will increase and the deterioration of the secondary battery will progress more. In this regard, according to such a configuration or method, the usage range is adjusted to be narrower than the rated usage range based on the frequency distribution of the charge amount based on the actual charge state of the secondary battery obtained for each charging opportunity. Therefore, by narrowing the rated utilization range and setting the fluctuation range of the rated charging state to the range in which the capacity reduction rate can be suppressed, the reduction in the capacity of the secondary battery can be suppressed.

As a preferable configuration, the upper limit value of the actual use range is smaller than the upper limit value of the rated use range, and the lower limit value of the actual use range is the lower limit value of the rated use range.
According to such a configuration, the lower limit value of the actual use range that moves to the lower side as the battery capacity decreases does not fall below the lower limit value of the rated use range.

According to the present invention, it is possible to suppress a decrease in the battery capacity of the secondary battery.

The block diagram which shows the schematic structure in 1st Embodiment of the control device of a secondary battery and the control method of a secondary battery. The graph which shows the relationship between the battery temperature and the battery capacity in the same embodiment. In the same embodiment, it is a schematic diagram showing the battery capacity and the usage range (SOC width), (a) is a diagram showing the rated usage range corresponding to the rated battery capacity, and (b) is the rated usage range and the actual battery capacity. (C) is a diagram in which the SOC [%] of the rated usage range is reflected in the actual battery capacity. The flowchart which shows the procedure of calculating the control SOC width in the same embodiment. The flowchart which shows the procedure of calculating the control SOC width in the same embodiment. The graph which shows the capacity reduction according to the setting of the control SOC width in the same embodiment. The graph which shows the frequency distribution of the charge amount for every charge opportunity in the same embodiment. The block diagram which shows the schematic structure in the 2nd Embodiment of the control device of a secondary battery and the control method of a secondary battery. In the same embodiment, a graph showing the relationship between ΔSOC obtained from the frequency distribution of the charge amount for each charging opportunity and the battery capacity decrease rate. The graph which shows the relationship between the total discharge electricity amount of a secondary battery and the capacity decrease in the same embodiment. The flowchart which shows the procedure of calculating the control SOC width in the same embodiment. The flowchart which shows the procedure of calculating the control SOC width in the same embodiment.

(First Embodiment)
A first embodiment of the secondary battery control device and the secondary battery control method will be described with reference to FIGS. 1 to 7. In the present embodiment, the charge state (SOC: System of Charge) [%] of the battery 10 is calculated as a ratio to the battery capacity of the battery 10 when fully charged. SOC "%" is a ratio of the amount of electricity actually charged in the battery 10 to the battery capacity. The SOC [%] can be calculated based on the charge / discharge history, and can also be calculated by a well-known method such as estimation of the voltage between terminals, impedance, and electromotive force.

The battery 10 has a rated battery capacity immediately after being manufactured, but the battery capacity becomes lower than the rated battery capacity depending on the continuation of use and temperature conditions. Therefore, hereinafter, the SOC with respect to the rated battery capacity of the battery 10 is described as the rated SOC, the battery capacity actually possessed by the battery 10 having a reduced battery capacity is referred to as the actual charge capacity, and the SOC with respect to the actual charge capacity is described as the actual SOC. To do. Further, the battery life of the battery 10 used in a vehicle or the like is longer when it is used in the range of use regulated as the SOC width than when it is used in the range of SOC 0 [%] to SOC 100 [%]. .. For example, the SOC width is defined as a range of SOC 20 [%] or more and SOC 60 [%] or less. Therefore, hereinafter, the SOC width with respect to the rated battery capacity will be referred to as the rated SOC width, and the SOC width with respect to the actual battery capacity will be referred to as the actual SOC width. The rated SOC width constitutes the rated use range, and the actual SOC width constitutes the rated use range.

The battery 10 is an alkaline secondary battery such as a nickel-hydrogen secondary battery, and is configured as a battery stack (assembled battery) in which a plurality of battery modules are connected. For example, a battery module is composed of 6 battery cells (cells). The battery cell is composed of a group of electrode plates in which a positive electrode plate and a negative electrode plate are laminated via a separator, and an alkaline electrolytic solution.

As shown in FIG. 1, the battery 10 measures the battery temperature measuring unit 11 that measures the temperature of the battery 10, the voltage measuring device 21 that measures the voltage between the terminals of the battery 10, and the charge / discharge current of the battery 10. A current measuring device 22 is provided. Further, the battery 10 is provided with a control device 30 required for charge / discharge control of the battery 10.

The battery temperature measuring unit 11 measures the temperature of the battery 10 and outputs a temperature signal corresponding to the measured temperature of the battery 10 to the control device 30. The voltage measuring device 21 outputs a voltage signal corresponding to the measured voltage between terminals of the battery 10 to the control device 30. The current measuring device 22 outputs a current signal corresponding to the measured charge / discharge current of the battery 10 to the control device 30.

The control device 30 calculates the actual charge capacity, rated SOC, actual SOC, and the like of the battery 10 based on the various acquired information. The control device 30 may display the rated battery capacity and rated SOC of the battery 10, the actual charge capacity and the actual SOC, or output to an external device that controls the drive of the battery load. The control device 30 acquires the battery temperature as the temperature of the battery 10 from the temperature signal input from the battery temperature measuring unit 11, and acquires the voltage between the terminals of the battery 10 from the voltage signal input from the voltage measuring device 21. The charge / discharge current of the battery 10 is acquired from the current signal input from the current measuring device 22.

Further, the control device 30 includes a processing unit 40 that performs calculation processing of the SOC of the battery 10 and the like, and a storage unit 50 that holds data for calculation of the SOC and the like of the battery 10. The processing unit 40 includes a computer and includes an arithmetic unit, a volatile memory, a non-volatile memory, and the like. Further, the processing unit 40 can exchange data with and from the storage unit 50. The storage unit 50 is a non-volatile storage device such as a hard disk or a flash memory, and holds various data.

With reference to FIG. 2, the storage unit 50 stores a temperature-battery capacity model 51 that includes data L21 showing the relationship between the battery temperature and the battery capacity. The data L21 indicates that the battery capacity does not decrease when the battery temperature is equal to or lower than the predetermined temperature Tb, while the battery capacity decreases when the battery temperature exceeds the predetermined temperature Tb.

Further, the storage unit 50 stores a plurality of parameters 53 used for various processes such as the rated battery capacity and the rated SOC width.
Further, the storage unit 50 stores data used for calculating each SOC of the battery 10 as SOC calculation data 54. For example, the SOC calculation data 54 includes calculation data showing the relationship between the SOC and the terminal voltage, which can calculate the SOC based on the terminal voltage. Further, the SOC calculation data 54 may include various initial values and calculation data that is appropriately updated.

The processing unit 40 includes a voltage / current acquisition unit 41, a battery temperature acquisition unit 42, and a battery capacity calculation unit 43 as an actual battery capacity acquisition unit. Further, the processing unit 40 includes a determination unit 44 for determining the necessity of updating the battery capacity, an SOC width calculation unit 45 as a usage range calculation unit for calculating the SOC width which is the usage range of the secondary battery, and the battery 10. The SOC calculation unit 46 is provided as a charge state calculation unit for calculating the charge electricity amount and the charge state.

The voltage / current acquisition unit 41 acquires the voltage between the terminals of the battery 10 based on the voltage signal, and acquires the charge / discharge current of the battery 10 based on the current signal. The battery temperature acquisition unit 42 acquires the battery temperature, which is the temperature of the battery 10, based on the temperature signal.

By applying the acquired battery temperature to the temperature-battery capacity model 51, the battery capacity calculation unit 43 can actually charge the battery 10 at the time of measurement based on the battery temperature at the time of measurement. Calculate the actual battery capacity as.

The determination unit 44 determines whether to use the rated battery capacity or the actual battery capacity for the control battery capacity. The determination unit 44 makes the control battery capacity correspond to the rated battery capacity when the battery temperature is equal to or lower than the predetermined temperature Tb, and makes the control battery capacity correspond to the actual battery capacity when the battery temperature exceeds the predetermined temperature Tb.

The SOC width calculation unit 45 calculates the relationship between the rated SOC width and the actual battery capacity, and the actual SOC width in the actual battery capacity. The SOC width calculation unit 45 can output the rated SOC width and the actual SOC width. Further, when the SOC width calculation unit 45 allocates the range of the amount of electricity [Ah] determined by the rated SOC width to the actual battery capacity, the SOC width calculation unit 45 calculates the corresponding SOC width from each SOC [%] of the upper limit and the lower limit of the actual battery capacity. be able to. Further, the actual SOC width can be calculated by applying each SOC [%] of the upper limit and the lower limit defined by the rated SOC width to the actual charge capacity as it is. These will be described in detail with reference to FIG.

With reference to FIG. 3A, at a predetermined temperature Tb or less set to include room temperature, the battery 10 secures a rated battery capacity C1, for example 6.5 [Ah]. The battery 10 has a rated SOC width W1 defined as a range of use based on the battery capacity, here the rated battery capacity C1. The range of use is a range in which the deterioration of battery performance is small and the use within that range is recommended for use in automobiles and the like. When the rated battery capacity C1 corresponds to 100 [%] of the rated SOC, the rated SOC width W1 is in the range of 20 [%] before and after (40 [%], for example, when the center of the width is 40 [%]. ), The lower limit is 20 [%] of the rated SOC, and the upper limit is 60 [%] of the rated SOC. At this time, in terms of electric energy, the rated SOC width W1 is 2.6 [Ah], the lower limit is 1.3 [Ah], and the upper limit is 3.9 [Ah].

With reference to FIG. 3B, when the battery temperature of the battery 10 exceeds a predetermined temperature Tb and becomes high, the battery capacity of the battery 10 decreases according to the data L21 of the temperature-battery capacity model 51. Here, assuming that the high temperature decrease amount C2 with respect to the rated battery capacity is 2.0 [Ah], the actual battery capacity C3 is 4.5 [Ah]. Assuming that the electric energy of the rated SOC width W1 is applied to this actual battery capacity, the actual SOC width W2 is 58 [%], the lower limit is 29 [%] of the actual SOC, and the upper limit is the actual SOC. Corresponds to 87 [%].

As described above, in the present embodiment, the SOC width of about 40 [%], the lower limit value of about 20 [%], and the upper limit value of about 60 [%] are the recommended ranges for use with respect to the battery capacity. Is. However, for the battery 10 whose battery capacity is reduced, the actual SOC width W2 has a large SOC width and a high upper limit value with respect to the usable range, so that the battery capacity may be reduced earlier.

With reference to FIG. 3 (c), the battery 10 shown in FIG. 3 (b) having the above-mentioned high temperature decrease amount C2 of 2.0 [Ah] and an actual battery capacity C3 of 4.5 [Ah]. , Appropriate range of use, that is, the ratio specified in the rated SOC width is applied based on 4.5 [Ah] of the actual battery capacity C3. That is, as the usage range for the actual battery capacity C3, for example, when the center of the width of the usage range is 40 [%], the range of 20 [%] before and after is defined as the actual SOC width W3 of 40 [%] of the SOC. At this time, the actual SOC width W3 has a width of 40 [%], the lower limit value is determined to be 20 [%] of the actual SOC, and the upper limit value is determined to be 60 [%] of the actual SOC. Expressing this in terms of the amount of electricity, the actual SOC width W3 is 1.8 [Ah], the lower limit is 0.9 [Ah], and the upper limit is 2.7 [Ah].

As described above, in the present embodiment, the SOC width of about 40 [%], the lower limit value of about 20 [%], and the upper limit value of about 60 [%] are the recommended ranges for use with respect to the battery capacity. Is. On the other hand, in the actual battery capacity C3 of the battery 10 whose battery capacity is reduced, the actual SOC width W3 is the recommended usage range, the SOC width is about 40%, the lower limit value is about 20%, and the upper limit is about 20%. Since the value is about 60%, the decrease in battery capacity can be suppressed.

The rated SOC width W1 defined as the usage range has a lower limit value of 1.3 [Ah] and an upper limit value of 3.9 [Ah], but the actual SOC width W3 has an upper limit value of 0.9 [Ah]. The value is 2.7 [Ah] and has a range of less than 1.3 [Ah] with respect to the rated SOC width W1. Since the range of less than the lower limit value of 1.3 "Ah" of the rated SOC width W1 is not suitable for the usage range of the battery 10, it is preferable that it is not included in the actual SOC width W3. Therefore, the SOC width calculation unit 45 may limit the lower limit value of the actual SOC width W3 to 1.3 [Ah].

As shown in FIG. 1, the SOC calculation unit 46 obtains a charge amount or SOC [%] based on the measured voltage between terminals of the battery 10 and the SOC calculation data 54, and is based on the obtained charge amount. The rated SOC [%] of the battery 10 is calculated and the actual SOC [%] is calculated (charge state calculation step).

<Operation of control device 30>
The operation of the control device 30 of the battery 10 will be described with reference to FIGS. 4 and 5.
When the charging / discharging of the battery 10 is started, the processing unit 40 of the control device 30 shown in FIG. 1 performs a control SOC width setting process. In the control SOC width setting process, the processing unit 40 calculates values required for setting the control SOC width, for example, the rated battery capacity, the actual battery capacity, the rated SOC width, the rated SOC, the actual SOC width, and the actual SOC. (Charge status calculation step).

As shown in FIG. 4, the processing unit 40 determines the end of the control SOC width calculation process (step S10 in FIG. 4), the control SOC width adjustment (step S11 in FIG. 4), and the SOC adjustment process (FIG. 4). Step S12) and steps S12) are sequentially executed as necessary.

First, the processing unit 40 executes the control SOC width calculation process (step S10 in FIG. 4).
As shown in FIG. 5, in the control SOC width calculation process (step S10 in FIG. 4), the battery temperature acquisition unit 42 of the processing unit 40 measures the battery temperature (battery temperature acquisition step: FIG. 5). Step S20) is performed. Further, the battery capacity calculation unit 43 applies the measured battery temperature to the temperature-battery capacity model 51 to calculate the actual battery capacity of the battery 10 (actual battery capacity acquisition step: step S21 in FIG. 5). The processing unit 40 performs a battery temperature determination (step S22 in FIG. 5) for determining whether or not the battery temperature is higher than a predetermined temperature Tb. Then, when it is determined that the battery temperature is higher than the predetermined temperature Tb (YES in step S22), the processing unit 40 sets the control SOC width based on the actual SOC width based on the actual battery capacity (utilization). Configure a range calculation step: step S23 in FIG. On the other hand, when it is determined that the battery temperature is equal to or lower than the predetermined temperature Tb (NO in step S22), the processing unit 40 sets the control SOC width based on the rated SOC width based on the rated battery capacity (NO). Configure the usage range calculation step: Step S24 in FIG.

As a result, the rated SOC width or the actual SOC width is set to the control SOC width, and the control SOC width calculation process (step S10 in FIG. 4) is completed.
Subsequently, in the control SOC width adjustment (step S11), the processing unit 40 sets the rated SOC calculated for the battery 10 to the control battery capacity (rated battery capacity or actual battery) which is the battery capacity corresponding to the control SOC width. Scale by (capacity) to calculate the control SOC. This makes it possible to control the charge / discharge of the battery 10 by applying the control SOC to the control SOC width.

In the end determination (step S12) of the control SOC width setting process, it is determined whether or not the end condition for ending the control SOC width setting process such as turning off the power of the automobile is satisfied. If it is not determined that the end condition is satisfied (NO in step S12), the processing unit 40 returns the execution process to the control SOC width calculation process (step S10) in order to continue the control SOC width setting process. .. On the other hand, when it is determined that the end condition of the control SOC width setting process is satisfied (YES in step S12), the processing unit 40 ends the control SOC width setting process.

The control device 30 manages the charge / discharge of the battery by the charge / discharge control unit of the charging device, the load device, or the like connected to the battery by outputting the calculated control SOC and the control SOC width. That is, the charge / discharge control unit charges / discharges the battery based on the control SOC and the control SOC width calculated by the control device 30, so that the battery 10 is appropriately charged / discharged.

<Effect>
The effects of this embodiment will be described with reference to FIGS. 6 and 7. Although the description will be given with the total discharge electricity amount [Ah] in FIG. 6, this also applies to the total charge electricity amount [Ah]. The total discharge electricity amount is a value obtained by accumulating only the discharge electricity amount from the start of use of the battery 10.

As shown in FIG. 6, the battery capacity of the battery 10 decreases as the total discharge electricity amount [Ah] increases. At this time, the total discharge electricity amount [Ah] roughly corresponds to the mileage of the vehicle. At this time, the graph L62 shows a mode in which the battery capacity is reduced when discharging is performed while the control SOC width is fixed at the rated SOC width. On the other hand, the graph L61 shows a mode of reducing the battery capacity when discharging is performed by selectively setting the control SOC width to the rated SOC width or the actual SOC width according to the battery temperature. When the total amount of discharged electricity [Ah] increases, the decrease in battery capacity of the graph L61 is smaller than that of the graph L62. That is, by selecting and setting the rated SOC width and the actual SOC width according to the battery temperature for the control SOC width, the decrease in the battery capacity corresponding to the total discharge electricity amount of the battery 10 can be suppressed. The capacity will be maintained.

In each graph L71 and L72 of FIG. 7, in the battery 10 in which charging and discharging are repeated, each charging amount is set for a predetermined period such as one trip of the amount of electricity (charging amount) for charging the battery 10 at one charging opportunity. The frequency distribution of appearance of is shown. Generally, if the amount of charge is large, the number of times of charging and discharging is small, which is convenient, but the amount of charge needs to be a size suitable for the battery capacity. That is, a large charge amount requires a corresponding large battery capacity (SOC width). However, if a large charge amount is charged to the corresponding battery 10 having no large battery capacity, the charge amount exceeds the SOC width, which may accelerate the decrease in the battery capacity.

Here, the graph L72 shows the frequency distribution of the charge amount when the charge / discharge control is performed while the control SOC width is fixed to the rated SOC width, and the charge amount is frequently a large value. That is, since both the battery 10 immediately after production and the battery 10 after being used for a long period of time are charged with the same charge amount, the battery capacity of the battery 10 whose battery capacity has decreased is reduced. Is easy to progress.

On the other hand, the graph L71 shows the frequency distribution of the charge amount when the charge / discharge control is performed by selectively changing the control SOC width to the rated SOC width or the actual SOC width according to the battery temperature. The charge amount is often smaller than that of the above. That is, since the battery 10 is charged with a charge amount regulated within the range specified by the control SOC width corresponding to the battery capacity of the battery 10, even if the battery 10 has a reduced battery capacity due to an increase in the battery temperature. , The decrease in battery capacity is suppressed.

According to this embodiment, the effects described below can be obtained.
(1) The battery 10 is used with a rated SOC width determined based on the rated battery capacity in order to suppress deterioration, but since the actual usable SOC width narrows depending on the usage environment and temperature, the rated SOC width There is a risk that deterioration will be accelerated even if it is used in. In this respect, the range of use corresponding to the battery capacity that changes according to the battery temperature is calculated as the actual SOC width, and the charge / discharge of the battery 10 can be controlled with respect to the actual SOC width. As a result, it is possible to suppress a decrease in the battery capacity of the battery 10.

(2) Whether the control SOC width used for control is the rated SOC width or the actual SOC width is appropriately selected depending on the battery temperature at which the battery capacity is changed.
(3) By obtaining the rated SOC for the rated battery capacity and the actual SOC for the actual battery capacity, it is possible to control the charge and discharge of the battery 10 based on the acquired actual SOC.

(4) Deterioration of the battery 10 is suppressed by charging and discharging the battery 10 within the actual SOC width.
(5) By setting the lower limit of the actual SOC width as the lower limit of the rated SOC width, the lower limit of the actual SOC width that moves lower as the battery capacity decreases does not fall below the lower limit of the rated SOC width. Will be.

(Second Embodiment)
A second embodiment of the secondary battery control device and the secondary battery control method will be described with reference to FIGS. 8 to 12. In this embodiment, the point that the control SOC width is set according to the frequency distribution of the charge amount in one charging opportunity (hereinafter referred to as one charging opportunity) is controlled based on the battery temperature in the first embodiment. It is different from the case of setting the SOC width for. In the following, the differences from the first embodiment will be mainly described, the same reference numerals will be given to the same configurations, and detailed description will be omitted.

As shown in FIG. 8, the battery 10 is provided with a battery temperature measuring unit 11, a voltage measuring device 21, a current measuring device 22, and a control device 30. The control device 30 includes a processing unit 40 and a storage unit 50.

The storage unit 50 stores the temperature-battery capacity model 51, the capacity reduction rate data 52, the parameter 53, and the SOC calculation data 54.
The capacity reduction rate data 52 is data showing the relationship between ΔSOC and the capacity reduction rate.

ΔSOC is a typical charge amount or the most frequent charge amount obtained based on the frequency distribution of the charge amount in the set of charge amounts for each charging opportunity. ΔSOC is specified based on the data of each graph L71, L72 of FIG. 7 of the first embodiment which is the frequency distribution of the charge amount. Here, the charge amount of one charge opportunity is calculated as an actual SOC with respect to the actual battery capacity, which is the battery capacity based on the current battery state.

The capacity reduction rate is the degree to which the battery capacity of the battery 10 decreases with respect to ΔSOC. When the battery 10 is charged with a predetermined charge amount, the capacity decrease rate is slow if the decrease in battery capacity is small, and the capacity decrease rate is high if the decrease in battery capacity is large.

In the present embodiment, the SOC width calculation unit 45 calculates the actual SOC in the actual battery capacity from the charge amount for each charging opportunity, obtains the calculated actual SOC, and obtains the calculated actual SOC of the set. Calculate ΔSOC from the frequency distribution.

With reference to the graph L101 of the capacity reduction rate data 52 of FIG. 9, ΔSOC shows a small value on the left side and a large value on the right side, and the capacity reduction rate shows a slow value on the lower side and a fast value on the upper side. As shown in the graph L101, the capacitance reduction rate and ΔSOC have a relationship in which the capacitance reduction rate is slow when ΔSOC is small, and conversely, the capacitance reduction rate is high when ΔSOC is large. Therefore, even if the charge amount for each charging opportunity is constant, the actual SOC increases because the ratio of the charge amount to the actual battery capacity increases as the actual battery capacity of the battery 10 decreases. The ΔSOC calculated based on the SOC frequency distribution also increases.

In the present embodiment, the control SOC width is changed based on the capacity reduction speed calculated from the capacity reduction speed data 52. Specifically, the control SOC width is changed according to the capacity reduction rate becoming higher than the threshold value Tc.

As shown in FIG. 10, in general, the battery capacity of the battery 10 decreases as the total discharge electricity amount [Ah] increases. At this time, the total discharge electricity amount [Ah] roughly corresponds to the mileage of the vehicle. The battery 10 immediately after production has a rated battery capacity because the total discharge electricity amount [Ah] is "0", has the highest battery capacity, and has a wide rated SOC width. Therefore, if charging / discharging based on the rated SOC width is continued, the actual battery capacity decreases, and the upper limit SOC of the rated SOC width increases as the ratio of the rated SOC width to the actual battery capacity increases. Along with this, as shown in the graph L111, the capacity reduction rate increases, so that the actual battery capacity falls below the maintenance capacity Td at the target life.

Therefore, in the present embodiment, the control SOC width is reduced from the rated SOC width whose capacity reduction is graph L111 under predetermined conditions so that the actual battery capacity is maintained at the maintenance capacity Td at the target life. Is changed to the maintenance SOC width of graph L112. The maintenance SOC width is an SOC width having a capacity reduction rate capable of maintaining the battery capacity at the maintenance capacity Td at the target life.

Note that graph L113 shows an example in which the capacity reduction of the SOC width can maintain the battery capacity at the maintenance capacity Td at the target life. For example, it is conceivable to set the SOC width corresponding to the graph L113 to the control SOC width from the beginning. However, since the decrease in battery capacity varies greatly depending on the usage environment of the battery 10, it is not easy to set an appropriate SOC width as the control SOC width from the beginning. In this regard, in the present embodiment, the control SOC width is changed from the rated SOC width to the maintenance SOC width according to the capacity reduction speed, so that the SOC width according to the usage environment of the battery 10 is appropriately set. Become.

In the parameter 53, the rated SOC width and the maintenance SOC width, which are set in the control SOC width, are set. The maintenance SOC width may be calculated or selected from a plurality of SOC widths as long as the SOC width capable of maintaining the battery capacity at the maintenance capacity Td is selected when the capacity reduction rate reaches the threshold value Tc. It may be something like that.

<Operation of control device 30 of battery 10>
The control SOC width setting process, which is the operation of the control device 30 of the battery 10, will be described with reference to FIGS. 11 and 12.

When the charging / discharging of the battery 10 is started, the processing unit 40 of the control device 30 shown in FIG. 8 performs a control SOC width setting process. In the control SOC width setting process, the processing unit 40 appropriately sets values required for setting the control SOC width, for example, the rated battery capacity, the actual battery capacity, the rated SOC width, the rated SOC, the actual SOC width, and the actual SOC. calculate.

As shown in FIG. 11, when the control SOC width setting process is started, the processing unit 40 measures the current value to measure the charging current value (step S30) and integrates the charging time to perform total charging electricity. The integrated time calculation (step S31) for calculating the quantity [Ah] is sequentially executed. Further, the processing unit 40 sequentially executes the charge amount frequency calculation process (step S32), the capacity reduction speed calculation (step S33), and the determination of the capacity reduction speed (step S34). Further, the processing unit 40 executes the control SOC width setting (step S35) according to the result of the determination of the capacity reduction speed (step S34).

Of these, as shown in FIG. 12, in the charge amount frequency calculation process (step S32), the processing unit 40 includes a battery temperature measurement (step S40 in FIG. 12) in which the battery temperature acquisition unit 42 measures the battery temperature, and a battery. The actual battery capacity calculation (step S41 in FIG. 12) for calculating the actual battery capacity by the capacity calculation unit 43 is sequentially executed. Further, the processing unit 40 executes the calculation of the charge amount for each charging opportunity (step S42 in FIG. 12) and the calculation of the actual charging state (step S43 in FIG. 12) in the SOC width calculation unit 45. Then, the processing unit 40 calculates the actual SOC based on the actual battery capacity from the charge amount for each charging opportunity by the SOC width calculation unit 45, and calculates the ΔSOC from the aggregated frequency distribution of the actual SOC. (Step S44 in FIG. 12) is executed. This completes the charge frequency calculation process (step S32).

Subsequently, as shown in FIG. 11, the processing unit 40 applies the ΔSOC calculated in the charge amount frequency calculation process (step S32) to the graph L101 of FIG. 9 to calculate the capacity reduction speed (FIG. 11). Step S33) of 11 is executed. Then, the processing unit 40 determines whether or not the capacity reduction rate is larger than the predetermined threshold value Tc (step S34 in FIG. 11).

When it is determined that the capacity reduction rate is equal to or less than a predetermined threshold value (NO in step S34 in FIG. 11), the processing unit 40 does not need to change the control SOC width, so that the control SOC width is set. The process ends once. In this case, the control SOC width setting process is repeatedly executed with a predetermined interval.

On the other hand, when it is determined that the capacity reduction rate is larger than the predetermined threshold value Tc (YES in step S34 of FIG. 11), the processing unit 40 sets the control SOC width for changing the control SOC width (step S35). To execute. The processing unit 40 changes the control SOC width from the rated SOC width to the maintenance SOC width. Then, the setting process is temporarily terminated. Normally, since the charge capacity of the battery 10 decreases as the total charge electricity amount increases, when the control SOC width is changed from the rated SOC width to the maintenance SOC width, the control SOC width is set after that. It doesn't have to be.

As described above, according to the present embodiment, in addition to the effects (1) to (4) described in the first embodiment, the following effects can be obtained.
(5) The control SOC width is adjusted to be narrower than the rated SOC width based on the frequency distribution of the actual SOC of the battery 10 obtained for each charging opportunity. Therefore, by narrowing the rated utilization range and setting the fluctuation range of the rated charging state to the range in which the capacity reduction rate can be suppressed, the reduction in the capacity of the battery 10 can be suppressed.

Each of the above embodiments can be modified and implemented as follows. Each of the above embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

-In the second embodiment, when the control SOC width is changed from the rated SOC width to the maintenance SOC width, the case where the control SOC width setting process does not have to be performed thereafter is illustrated. However, the present invention is not limited to this, and if the control SOC width can be further changed, the control SOC width setting process may be performed after changing the control SOC width. At this time, for example, it is conceivable to set the SOC width narrower than the maintenance SOC width.

-In each of the above embodiments, the control device 30 outputs the calculated control SOC and control SOC width to a charge / discharge control unit such as a charging device or a load device to appropriately charge / discharge the battery 10. The case where it is possible is illustrated. However, the present invention is not limited to this, and the control device may manage the charging / discharging of the battery by the load device or the charging / discharging device connected to the battery. This also makes it possible to appropriately charge and discharge the battery based on the control SOC and the control SOC width calculated by the control device.

-In the first embodiment, the case where the output of the control device 30 is used by the charge / discharge control unit has been illustrated, but the present invention is not limited to this, and the control device may include the charge / discharge control unit.
-In each of the above embodiments, the case where the battery 10 is a battery module has been illustrated, but the present invention is not limited to this, and the battery may be a battery stack, a battery block, or a battery cell. In this case, the usage range and the like may be calculated for the battery stack, the battery block, and the battery cell.

-In each of the above embodiments, the case where the battery 10 is mounted on the vehicle is illustrated. This vehicle includes electric vehicles and hybrid vehicles, as well as gasoline-powered vehicles and diesel vehicles equipped with batteries. Further, the battery may be used as a moving body other than an automobile or as a fixed power source as long as the range of use is set.

10 ... Battery, 11 ... Battery temperature measuring unit, 21 ... Voltage measuring device, 22 ... Current measuring device, 30 ... Control device, 40 ... Processing unit, 41 ... Voltage / current acquisition unit, 42 ... Battery temperature acquisition unit, 43 ... Battery Capacity calculation unit, 44 ... determination unit, 45 ... SOC width calculation unit, 46 ... SOC calculation unit, 50 ... storage unit, 52 ... capacity reduction rate data, 53 ... parameter, 54 ... SOC calculation data.

Claims (9)

A battery temperature acquisition unit that acquires the battery temperature of an alkaline secondary battery,
By applying the acquired battery temperature to the relationship between the predetermined battery temperature and the actual battery capacity which is the rechargeable battery capacity of the secondary battery at the battery temperature, the battery temperature is dealt with. The actual battery capacity acquisition unit that acquires the actual battery capacity,
A secondary battery control device including a usage range calculation unit that calculates the actual usage range so that the rated usage range determined for the rated battery capacity of the alkaline secondary battery corresponds to the actual battery capacity. The usage range calculation unit outputs the actual usage range calculated by the usage range calculation unit when the battery temperature is higher than a predetermined temperature, and when the battery temperature is equal to or lower than the predetermined temperature, the rated utilization The secondary battery control device according to claim 1, which outputs a range. Claim 1 or 2 further includes a charge state calculation unit that calculates the value of the rated charge state with respect to the rated battery capacity and calculates the value of the actual charge state with respect to the actual battery capacity from the calculated value of the rated charge state. The described secondary battery control device. The secondary battery control device according to claim 3, further comprising a charge / discharge control unit that controls charging / discharging of the alkaline secondary battery so as to be performed within the practical use range. The actual charge state calculated by the charge state calculation unit is stored, the charge amount for each charging opportunity is acquired based on the actual charge state, and the frequency distribution of the acquired charge amount is divided into the frequency distribution and the capacity decrease. The capacity reduction rate is acquired by applying it in relation to the speed, and when the acquired capacity reduction rate becomes larger than the switching threshold value, the output usage range is narrowed to the rated usage range according to claim 3 or 4. The described secondary battery control device. The upper limit of the actual use range is smaller than the upper limit of the rated use range.
The secondary battery control device according to any one of claims 1 to 5, wherein the lower limit value of the actual use range is the lower limit value of the rated use range. Battery temperature acquisition step to acquire the battery temperature of the alkaline secondary battery,
By applying the acquired battery temperature to the relationship between the predetermined battery temperature and the actual battery capacity which is the rechargeable battery capacity of the secondary battery at the battery temperature, the battery temperature is dealt with. The actual battery capacity acquisition step for acquiring the actual battery capacity and
A method for controlling a secondary battery, comprising: a usage range calculation step of calculating an actual usage range so that a rated usage range determined for the rated battery capacity of the alkaline secondary battery corresponds to the actual battery capacity. The seventh aspect of claim 7, further comprising a charge state calculation step of calculating the value of the rated charge state with respect to the rated battery capacity and calculating the value of the actual charge state with respect to the actual battery capacity from the calculated value of the rated charge state. How to control the secondary battery. The actual charge state calculated by the charge state calculation step is stored, the charge amount for each charging opportunity is acquired based on the actual charge state, and the frequency distribution of the charge amount acquired for each charge opportunity is calculated as the frequency. Claim that the capacity reduction rate is acquired by applying to the relationship between the distribution and the capacity reduction rate, and when the acquired capacity reduction rate becomes larger than the switching threshold value, the output usage range is narrower than the rated usage range. 8. The method for controlling a secondary battery according to 8.