JP6351347B2 - Charge / discharge control device and charge / discharge control method - Google Patents

Description

  The present invention relates to a charge / discharge control device and a charge / discharge control method, and in particular, a charge / discharge control device and charge / discharge control for minimizing heat generation of a storage battery at the end of charge / discharge and suppressing deterioration of the storage battery due to heat generation of charge / discharge. Regarding the method.

  As a control method of a storage battery, it is common to charge and discharge with a constant current. At this time, the amount of heat generated is small at the beginning of charging and discharging, and the temperature rise of the storage battery accompanying charging and discharging is small. However, at the end of charge / discharge, the amount of heat generation increases, so the temperature rise of the storage battery increases. As a result, the temperature of the storage battery rises, and the life of the storage battery decreases due to the temperature rise.

  In the conventional charge / discharge control method for a storage battery, for example, as described in Patent Document 1, the value of the current I of the storage battery being charged and discharged and the value of the voltage V between terminals are used, and the value of the internal resistance is r. The open end voltage Voc is estimated from the relational expression of Voc = V−Ir. Next, the SOC is estimated based on a relational expression between the estimated open-circuit voltage Voc and a previously determined SOC (State of Charge: remaining capacity of the storage battery). Thereafter, the setting of the charging current value is changed so that the charging power value decreases as the absolute value of ΔSOC = target SOC−estimated SOC, which is a deviation between the estimated SOC and the target SOC, decreases.

  According to Patent Document 2, a storage battery is rapidly charged with a constant current, and overcharge is detected by a change per unit time (temperature differential value) of the battery temperature as the charging progresses, and charging is stopped or terminated.

  According to Patent Document 3, after charging the storage battery in the constant current mode until the set battery voltage value is reached, the battery is charged by moving to the constant voltage mode. Further, a threshold T1 is provided for the battery temperature increase ΔT from the battery temperature T0 when switching to the constant voltage mode, and when the battery temperature increase ΔT becomes larger than the threshold T1 in the charging process in the constant voltage mode, The charging of the storage battery is terminated.

  According to Patent Document 4, when the temperature change per unit time (temperature differential value) in the charging process in the constant current mode becomes equal to or less than a preset value, from the voltage value set at the start of charging, Change to the set voltage value for the battery temperature at the time.

JP 2013-42598 A Japanese Patent No. 3737150 Japanese Patent No. 3638369 JP 09-107638 A

  In the said patent document 1, since the influence of the temperature of a storage battery is not considered, when the temperature of a storage battery rose unexpectedly, there existed a problem that the lifetime of a storage battery will fall by the said temperature rise.

  In the above Patent Documents 2 to 4, since the influence of the temperature of the storage battery is taken into consideration, the problem of the above Patent Document 1 is solved. Only the rise is considered, and the initial stage of energization (the initial stage of charging or the initial stage of discharging) is not considered. In general, a storage battery has a problem that the temperature of the storage battery is low because it generates little heat at the beginning of energization, and the resistance value of the storage battery is high in a low temperature state. However, in any of Patent Documents 1 to 4, there is a problem that the performance of the storage battery deteriorates in the initial stage of energization because the performance deterioration of the storage battery at low temperatures is not taken into consideration.

  The present invention has been made to solve such a problem, and a storage battery at a low temperature at the beginning of energization (initial charge or discharge) while suppressing heat generation of the storage battery at the end of energization (end of charge or end of discharge). An object of the present invention is to obtain a charge / discharge control device and a charge / discharge control method capable of suppressing the performance degradation.

The present invention is a charge / discharge control device for controlling charge / discharge of the storage battery in a storage battery system comprising a storage battery that performs charge / discharge and a storage battery management device that measures an SOC indicating a charge rate of the storage battery, An SOC range determination unit that determines a plurality of SOC ranges by dividing the entire SOC from the minimum charging rate to the maximum charging rate, and a current value for charging and discharging the storage battery for each SOC range. A current value determining unit that determines a value, and a charge / discharge unit that calculates the SOC range including the current SOC measured by the storage battery management device, and charges and discharges the storage battery with the current value corresponding to the SOC range The current value determining unit sets a weighting coefficient for each SOC range, and multiplies a reference current value by the weighting coefficient to determine the current value for each SOC range. And, wherein the weighting factor, the value is the largest weighting coefficient corresponding to SOC range of the charge and discharge initial, then gradually decreases and, as the value of the weighting coefficient corresponding to SOC range of the charge and the discharge ending is minimized It is a charge / discharge control device that is set and has a maximum discharge current at the beginning of discharge and then gradually decreases as the SOC value decreases during discharge .

  In the charge / discharge control device according to the present invention, the current value is reduced at the end of energization of the storage battery (the end of charge or the end of discharge), thereby suppressing the heat generation due to the charge / discharge of the storage battery and extending the life of the storage battery. Compared with charging / discharging at a constant current, the current value at the initial stage of energization (initial stage of charging or initial stage of discharging) is set larger, so that it is possible to suppress performance degradation at low temperatures in the initial stage of energization.

1 is a block diagram showing a configuration of a storage battery system provided with a charge / discharge control device according to Embodiment 1 of the present invention. FIG. It is the block diagram which showed the structure of the charging / discharging control apparatus which concerns on Embodiment 1 of this invention. It is the figure which showed the change of the electric current with respect to SOC, a voltage, and storage battery temperature at the time of performing constant current charge with the charging / discharging control method of a prior art example. It is the figure which showed the change of the electric current with respect to SOC, a voltage, and storage battery temperature at the time of charging with the charging / discharging control method in Embodiment 1 of this invention. It is the figure which showed the change of the electric current with respect to SOC, a voltage, and storage battery temperature at the time of performing constant current discharge by the charging / discharging control method of a prior art example. It is the figure which showed the change of the electric current with respect to SOC, a voltage, and storage battery temperature at the time of discharging with the charging / discharging control method in Embodiment 1 of this invention. It is the figure which charged with the charging / discharging control method in Embodiment 1 of this invention, and showed the charging current value and storage battery temperature when storage battery temperature exceeded a regulation value in the middle of charging. It is the figure which performed the discharge with the charging / discharging control method in Embodiment 1 of this invention, and showed the discharge current value and storage battery temperature when storage battery temperature exceeded a regulation value in the middle of discharge. 3 is a flowchart of a charge / discharge control method according to Embodiment 1 of the present invention. It is explanatory drawing which showed the change of the capacity retention rate of the storage battery in Embodiment 1 of this invention.

  Hereinafter, a charge / discharge control device and a charge / discharge control method according to embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a storage battery system according to Embodiment 1 of the present invention. As the storage battery system according to the first embodiment, for example, charging / discharging to effectively use surplus power generated by PV (Photovoltaic: photovoltaic power generation) and inexpensive late-night power of electricity bills installed in a smart house, for example. In addition, a storage battery system that is also used as an emergency power source during a power failure will be described as an example. The storage battery system performs charging / discharging according to PV output fluctuations and load fluctuations, and makes it possible to extend the life of the storage battery system by optimally controlling charging / discharging. However, this is merely an example, and it may be used for other purposes.

  As shown in FIG. 1, the storage battery system 7 includes a storage battery 5, a battery management unit 4 (hereinafter referred to as BMU 4), a temperature measurement circuit 3, and a charge / discharge control device 2, and is connected to the power source 1 during charging. And connected to the load 6 during discharging.

  The storage battery 5 is a rechargeable secondary battery composed of a lead storage battery, a nickel metal hydride battery, or a lithium ion battery, and has a single cell or module configuration.

  The temperature measurement circuit 3 measures the temperature of the storage battery 5. The temperature measurement circuit 3 may be any one as long as it has a configuration capable of measuring the temperature of the storage battery 5, for example, a thermometer or a temperature sensor.

  The BMU 4 is a storage battery management device that has a protection function and a state monitoring function for safety management of the storage battery 5 and acquires information on the storage battery 5 based on these functions. Specifically, if overcharge, overdischarge, overvoltage, overcurrent, temperature abnormality, or the like occurs in the storage battery 5, the BMU 4 stops the operation (charge / discharge) of the storage battery 5 with a protection function. In addition, the BMU 4 uses a state monitoring function to store battery states such as voltage measurement, current measurement, electric energy measurement, charge / discharge management, and remaining capacity management (that is, measurement of SOC indicating the charging rate of the storage battery 5). Monitor.

  The charge / discharge control device 2 calculates a current value and limits the charge / discharge current from information (charge state (SOC) and storage battery temperature) obtained from the BMU 4 and the temperature measurement circuit 3.

  As shown in FIG. 2, the charge / discharge control device 2 divides the entire SOC from the minimum charging rate (0%) to the maximum charging rate (100%) of the storage battery 5 into a plurality of sections for each SOC value. The SOC range determination unit 21 that determines the SOC range of the current, the current value determination unit 22 that determines the value of the current value for charging and discharging the storage battery 5 for each SOC range, and the current SOC measured by the BMU 4 are included. And a charge / discharge unit 23 that charges and discharges the storage battery 5 with a current value corresponding to the SOC range. Further, when the temperature of the storage battery 5 rises and reaches a preset limit during the charging / discharging operation, the charging / discharging unit 23 corresponds to the SOC range instead of the current value corresponding to the SOC range. The storage battery 5 is charged / discharged with a specified value set to a value equal to or less than the current value.

  Hereinafter, operation | movement of the charging / discharging control apparatus 2 in this Embodiment is demonstrated.

First, the charging operation of the charge / discharge control device 2 will be described.
The charging / discharging control device 2 determines a reference charging current value (hereinafter referred to as a reference current value I) with reference to the rated capacity of the storage battery 5 by the charging / discharging unit 23 before starting charging. .
Next, the charge / discharge control device 2 determines the SOC range by the SOC range determination unit 23. The SOC is a charging rate indicating the remaining storage capacity of the storage battery 5 and is represented by a numerical value of 0% to 100%. The charge / discharge control device 2 divides this 0% to 100% for each range width set in advance, and sets each SOC range. Here, in order to simplify the description, the range width set in advance will be described as 10% intervals. In that case, 0 to 10% is the first SOC range, 10 to 20% is the second SOC range, 20 to 30% is the third SOC range, ..., 90 to 100% is the tenth range. The entire SOC is divided like the SOC range, and a total of 10 SOC ranges are determined. The SOC range width is not limited to 10% and may be arbitrarily determined. However, it is preferable to set the SOC range width as small as possible so that the case where the storage battery 5 becomes abnormal can be detected quickly. Moreover, although SOC 0% was described as the minimum charging rate and SOC 100% was described as the maximum charging rate, these values may be arbitrarily determined.
Next, the charge / discharge control device 2 determines the current value when charging is performed for each SOC range by the current value determination unit 22. In the present embodiment, the current value is determined by weighting each SOC range. Specifically, as shown in the lower graph of FIG. 4, the weighting coefficients α ₁ , α ₂ , α ₃ ,..., Α ₁₀ are set to α ₁ > α ₂ > α ₃ for each SOC range. >...> α ₁₀ > 0. That is, the weighting coefficient value is set to decrease as the SOC value increases. At this time, the reduction range of the weighting coefficient may always be the same or different. That is, the value of each weighting coefficient may be monotonously decreased or the amount of decrease may vary. The current value determining unit 22 multiplies the reference current value I by the value of the weighting coefficient α _n (n = 1,..., 10) determined in this way, and the current when charging in each SOC range. Determine the value (= α _n I). As shown in FIG. 4, the current value is greatest at the initial stage of charging (SOC = 0%), then gradually decreases in a step-like manner, and is smallest at the end of charging (SOC = 100%). Yes. Note that the current value (= α ₁ I) at the initial stage of charging (SOC = 0%) needs to be set so as not to exceed the maximum allowable current value of the storage battery, but is optional if it does not exceed the maximum allowable current value You may decide.
Next, the charge / discharge control device 2 obtains the SOC range including the current SOC measured by the BMU 4 by the charge / discharge unit 22 and charges the storage battery 5 with the current value corresponding to the SOC range.

Similarly, in the case of discharging, the charge / discharge control device 2 determines each SOC range by the SOC range determination unit 21. Here, in order to simplify the description, the preset range width is described as 10% intervals. In this case, 100 to 90% is the first SOC range, and 90 to 80% is the second SOC. The range is divided such that 80 to 70% is the third SOC range,..., 10 to 0% is the tenth SOC range, and a total of ten SOC ranges are determined. The SOC range width is not limited to 10% and may be arbitrarily determined. However, it is preferable to set the SOC range width as small as possible so that the case where the storage battery 5 becomes abnormal can be detected quickly.
Next, the charge / discharge control apparatus 2 determines the current value at the time of discharging for each SOC range by the current value determination unit 22. That is, the current value is determined by weighting each SOC range. Specifically, as shown in the lower graph of FIG. 6, the weighting coefficients α ₁ , α ₂ , α ₃ ,..., Α ₁₀ are set to α ₁ > α ₂ > α ₃ for each SOC range. >...> α ₁₀ > 0. That is, the weighting coefficient value is set to decrease as the SOC value decreases. At this time, the reduction range of the weighting coefficient may always be the same or different. That is, the value of each weighting coefficient may be monotonously decreased or the amount of decrease may vary. The charge / discharge control device 2 multiplies the reference current value I by the value of the weighting coefficient α _n (n = 1,..., 10) determined in this way, and the current when charging in each SOC range. Determine the value (= α _n I). As shown in FIG. 6, the current value is greatest at the initial stage of discharge (SOC = 100%), then gradually decreases in a step-like manner, and is smallest at the end of discharge (SOC = 0%). Yes. Note that the current value (= α ₁ I) at the initial stage of discharge (SOC = 100%) needs to be set so as not to exceed the maximum allowable current value of the storage battery, but is optional if it does not exceed the maximum allowable current value You may decide.
Next, the charging / discharging control device 2 obtains the SOC range including the current SOC measured by the BMU 4 by the charging / discharging unit 22, and discharges the storage battery 5 at a current value corresponding to the SOC range.

In the present embodiment, the charging / discharging control device 2 determines the current value at the time of charging / discharging by weighting each SOC range in this way, and ends the energization of the storage battery 5 (the end of charging or the end of discharging). ), The heat generation due to charging / discharging of the storage battery 5 can be suppressed, and the deterioration of the storage battery 5 can be prevented.
In addition, as described above, generally, at the initial stage of energization (the initial stage of charging or the initial stage of charging), the storage battery 5 does not generate heat and is at a low temperature, so its resistance value tends to be large and performance tends to deteriorate. In this embodiment, the current value at the initial stage of energization (initial charge or initial charge) of the storage battery 5 is set to a large value, so that compared to the conventional case where charging / discharging is performed at a constant current, Since the amount of heat generated in the middle of energization increases and the temperature of the storage battery 5 increases, the resistance value can be reduced, and the performance deterioration of the storage battery 5 at low temperatures can be prevented.

  FIG. 3 illustrates the storage battery voltage, storage battery temperature, and current value when a conventional storage battery is charged with a constant current. When charging at a constant current, the charge is constant from the initial charge (SOC = 0%) to the end of charge (SOC = 100%), so the amount of heat generated increases at the end of charge and the temperature of the storage battery is charged. It becomes hot at the end. At this high temperature, the storage battery deteriorates and the life of the storage battery decreases. On the other hand, at the initial stage of charging, since the temperature of the storage battery is low, the resistance value of the storage battery is high and sufficient performance is not expected.

  FIG. 4 shows the storage battery voltage, storage battery temperature, and current value when charging is performed with the current value when the current value is determined for each SOC range in the present embodiment. By setting the current value to the largest value at the initial stage of charging (SOC = 0%), the heat generation of the storage battery 5 is increased at the initial stage of charging (SOC = 0%), and as the end of charging period (SOC = 100%) is reached, the current value It is possible to reduce the heat generation of the storage battery 5 by reducing. With this charging method, heat generation can be increased at the beginning of charging (SOC = 0%) when the temperature of the storage battery 5 is low, and performance deterioration of the storage battery 5 at low temperatures can be prevented. Further, by reducing the heat generation of the storage battery 5 at the end of charging (SOC = 100%), the storage battery 5 can be prevented from deteriorating and the life of the storage battery 5 can be extended.

  FIG. 5 shows the storage battery voltage, storage battery temperature, and current value when the conventional storage battery 5 is discharged at a constant current. In the case of discharging at a constant current, since the discharge is performed constantly from the initial stage of discharge (SOC = 100%) to the end of discharge (SOC = 0%), the calorific value increases at the end of discharge, and the temperature of the storage battery 5 is High temperature at the end of discharge. At this high temperature, the storage battery deteriorates and the life of the storage battery decreases. On the other hand, at the initial stage of charging, since the temperature of the storage battery is low, the resistance value of the storage battery is high and sufficient performance is not expected.

  FIG. 6 shows the storage battery voltage, storage battery temperature, and current value when discharging is performed at the current value when the current value is determined in each SOC range in the present embodiment. By setting the current value to be large at the initial stage of discharge (SOC = 100%), the heat generation of the storage battery 5 is increased at the initial stage of discharge, and the current value is decreased as the end of discharge (SOC = 0%) is reached. 5 can be reduced. By this charging method, heat generation can be increased at the initial stage of discharge (SOC = 100%) when the temperature of the storage battery 5 is low, and performance deterioration of the storage battery 5 at low temperatures can be prevented. Further, it is possible to extend the life of the storage battery 5 by reducing the heat generation of the storage battery 5 at the end of discharge (SOC = 0%).

In the present embodiment, as described above, charging / discharging is performed with the current value (= α _n I) weighted by the weighting coefficient α _n that gradually decreases stepwise for each SOC range set by the charge / discharge control device 2. However, if the temperature of the storage battery 5 exceeds the “limit” during the charging / discharging, the current value is set to a preset specified value instead of the weighted current value (= α _n I). Then, charging / discharging is performed while controlling the temperature of the storage battery 5 to decrease. This will be described below with a specific example.

  First, the “limit” regarding the temperature of the storage battery 5 will be described. In the present embodiment, the following two conditions are set as the “limit”, and when any one of them is satisfied, it is determined that the temperature of the storage battery 5 has exceeded the “limit”.

Condition 1: When the temperature rise amount (dT / dSOC) of the storage battery 5 exceeds a preset rise threshold value ΔT in an arbitrary n-th SOC range (SOC _n ) (that is, dT / dSOC> ΔT). If)
Condition 2: When the temperature T _SOCn of the storage battery 5 in a certain arbitrary n-th SOC range (SOC _n ) exceeds a preset temperature upper limit value T _LIMIT (that is, when T _SOCn > T _LIMIT ) .

When the temperature of the storage battery 5 satisfies any one of the condition 1 and the condition 2 in any arbitrary nth SOC range, the charge / discharge control device 2 is the SOC range next to the nth SOC range. That is, the current value for charging / discharging in the (n + 1) th SOC range is not set to α _{n + 1} I corresponding to the SOC range, but is re-set to a specified value I _min set to a smaller value, and the storage battery 5 Charge and discharge to minimize heat generation. The value of the prescribed value I _min may be arbitrarily set, but is set to a value that is the same as or smaller than α ₁₀ I, which is the smallest value among α _n I. For example, in the example of FIG. 7, since the storage battery 5 exceeded the limit in the third SOC range of SOC = 20 to 30%, the current value in the next fourth SOC range (SOC = 30 to 40%) is The specified value I _min is set. Similarly, in the example of FIG. 7, since the storage battery 5 exceeded the limit in the sixth SOC range of SOC = 50 to 60%, the current value in the next seventh SOC range (SOC = 60 to 70%) is The specified value _Imin . Here, the value of the specified value I _min is set to I _min = 0.5I. In addition, when the storage battery 5 is cooled by charging at the specified value I _min and the temperature of the storage battery 5 does not correspond to any of the condition 1 and the condition 2, the current value α _n corresponding to each SOC range again. Charge with I. In the example of FIG. 7 as well, the fourth SOC range (SOC = 30 to 40%) charged at the specified value I _min and the fifth SOC range following the seventh SOC range (SOC = 60 to 70%). In the eighth SOC range, charging is performed with current values α ₅ I and α ₈ I corresponding to the respective SOC ranges. Hereinafter, a more detailed description will be given using the examples of FIGS. 7 and 8.

FIG. 7 is a diagram illustrating a charging current value when charging is performed by the charging control method according to the present embodiment, and the storage battery temperature exceeds a specified value during charging. In the example of FIG. 7, as described above, the SOC range is in the range of SOC 20 to 30% and 50 to 60%, and the temperature of the storage battery 5 exceeds the limit. These cases will be described below.
First, in the example of FIG. 7, the SOC range is in the range of SOC 20 to 30%, and the temperature of the storage battery 5 exceeds the limit. That is, when the SOC range is SOC 20 to 30% and the storage battery temperature increase (dT / dSOC) exceeds the increase threshold ΔT (that is, when dT / dSOC> ΔT), or the storage battery temperature T _SOCn is A case where the temperature upper limit value T _LIMIT is exceeded (that is, a case where T _SOCn > T _LIMIT is satisfied) is shown. In this case, in the present embodiment, the current value in the range of SOC 30 to 40%, which is the SOC range next to the SOC range, is suppressed to a preset specified value (charging current = 0.5I). That is, the current value in the range of SOC 30 to 40% should be originally charging current = α ₄ I, but the temperature of the storage battery 5 exceeded the limit when the SOC range was SOC 20 to 30%. The charging current is suppressed to a preset specified value (charging current = 0.5I), and charging is performed so that the heat generation of the storage battery 5 is minimized.
In the example of FIG. 7, the SOC range is in the range of SOC 50 to 60%, and the temperature of the storage battery 5 again exceeds the limit. That is, when the temperature increase amount (dT / dSOC) of the storage battery 5 exceeds the increase threshold ΔT (that is, when dT / dSOC> ΔT), or when the storage battery temperature T _SOCn exceeds the temperature upper limit value T _LIMIT (That is, when T _SOCn > T _LIMIT ). Therefore, the current value in the range of SOC 60 to 70%, which is the SOC range next to the SOC range, is suppressed to a preset specified value (charging current = 0.5I).

FIG. 8 is a diagram showing a discharge current value when discharge is performed by the discharge control method in the present embodiment and the storage battery temperature exceeds a specified value during discharge.
In the example of FIG. 8, the temperature of the storage battery 5 exceeds the limit in the third SOC range (SOC 80 to 70%) and the sixth SOC range (SOC 50 to 40%). That is, in the third and sixth SOC ranges, the temperature increase amount of the storage battery 5 has exceeded the increase threshold ΔT (that is, dT / dSOC> ΔT), or the temperature of the storage battery 5 has exceeded the temperature upper limit value T _LIMIT The case (ie, Tsoc> T _LIMIT ) is shown as an example. In the present embodiment, as in the case of charging in FIG. 7, the fourth SOC range (SOC 70 to 60%) and the seventh SOC range, which are the SOC ranges next to the SOC range in which the storage battery 5 has exceeded the temperature limit, are used. At (SOC 40 to 30%), the current value for discharging is suppressed to a preset specified value I _min (discharge current = 0.5I).
When the storage battery 5 is cooled by charging at the specified value I _min and the temperature of the storage battery 5 does not correspond to either of the conditions 1 and 2, the current value α _n I corresponding to each SOC range is again used. Discharge. Also in the example of FIG. 8, the fourth SOC range (SOC = 70 to 60%) in which charging is performed at the specified value I _min and the fifth SOC range next to the seventh SOC range (SOC = 40 to 30%) are performed. In the eighth SOC range, charging is performed with current values α ₅ I and α ₈ I corresponding to the respective SOC ranges.

In the above example, there has been a prescribed value I _min in discharging a specified value I _min when the charge to the same value, not limited to the case, may be set to different values.

As described above, in the present embodiment, when the temperature of the storage battery 5 exceeds the limit, charging / discharging is performed by setting a small charge / discharge current value in the SOC range next to the SOC range exceeding the limit. Thus, it is possible to prevent the temperature of the storage battery 5 from rising. Thus, in this Embodiment, when the temperature of the storage battery 5 exceeds the restrictions of the conditions 1 and 2, the charge / discharge current value is limited to the preset specified value _Imin , and the storage battery 5 is cooled. By continuing charging / discharging, deterioration by the temperature rise of the storage battery 5 can be prevented, and the lifetime of the storage battery 5 can further be improved.

  The flowchart of FIG. 9 summarizes the charging / discharging method of the storage battery 5 of the charging / discharging control apparatus 2 in this Embodiment mentioned above. FIG. 9 shows a process of charging / discharging the storage battery 5.

In FIG. 9, the charge / discharge control device 2 first determines whether to charge or discharge the storage battery 5 based on information on the state of charge obtained from the BMU 4 (SOC value of the storage battery 5). As a result of the determination, when the storage battery 5 is charged (step S101), a reference charging current value (that is, a reference current value I) is determined with reference to the rated capacity of the storage battery 5 (step S102). Next, the SOC range is determined (step S103), and the current value in each SOC range is determined (step S104). Since the method for determining the SOC range and the method for determining the current value α _n I in each SOC range are as described above, the description thereof is omitted here. Thereafter, the temperature (cell temperature) of the storage battery 5 is measured using information from the temperature measurement circuit 3 (step S105), and it is determined whether the measured storage battery 5 temperature is a preset usable temperature (step S106). If the temperature is not the usable temperature, the process returns to step S105 and waits until the temperature of the storage battery 5 reaches the usable temperature. On the other hand, if the temperature of the storage battery 5 is a usable temperature, charging is started (step S107). During charging, the SOC range including the current SOC is obtained sequentially based on the state of charge information (SOC value of the storage battery 5) obtained from the BMU 4, and charging is performed with the current value corresponding to the SOC range. Do. Furthermore, during charging, for each SOC range, the temperature of the storage battery 5 is measured using information from the temperature measurement circuit 3, and whether the temperature of the storage battery 5 has reached a preset temperature upper limit value _TLIMIT , Alternatively, it is determined whether or not the temperature increase amount of the storage battery 5 is greater than a preset increase threshold value ΔT (step S108). As a result of the determination, when the temperature of the storage battery 5 reaches a preset temperature upper limit value T _LIMIT , or when the temperature increase amount of the storage battery 5 is greater than a preset increase threshold value ΔT, the current value for charging is set. suppressing the preset specified value I _min (step S109), the heat generation of the battery 5 to charge so as to minimize. When the temperature of the storage battery 5 becomes smaller than the preset temperature upper limit value _{TLIMIT due} to this charging, or when the temperature rise amount of the storage battery 5 becomes smaller than the preset increase threshold value ΔT (step S110), again. Then, charging is performed with a current value corresponding to each SOC range (step S107). On the other hand, as a result of the determination in step S108, when the temperature of the storage battery 5 does not reach the temperature upper limit value T _LIMIT , or when the temperature increase amount of the storage battery 5 is smaller than the increase threshold value ΔT, each determined in step S104 Charging is performed at a current value α _n I corresponding to the SOC range, and when the SOC of the storage battery 5 reaches the upper limit SOC that is the rated capacity of the storage battery 5, the charging is terminated (step S111).

On the other hand, when the storage battery 5 is discharged as a result of the determination in step S101, a reference discharge current value (that is, a reference current value I) is determined with reference to the rated capacity of the storage battery 5 (step S202). Next, the SOC range is determined (step S203), and the current value in each SOC range is determined (step S204). Since the determination method of the SOC range and the determination method of the current value α _n I in each SOC range are as described above, the description thereof is omitted here. Thereafter, the temperature of the storage battery 5 is measured using information from the temperature measurement circuit 3 (step S205), and it is determined whether the measured temperature of the storage battery 5 is a usable temperature (step S206). In step S205, the process returns to step S205 and waits until the temperature of the storage battery 5 reaches the usable temperature. On the other hand, if the temperature is usable, discharging is started (step S207). During the discharge, the SOC range including the current SOC is sequentially obtained based on the state of charge information (SOC value of the storage battery 5) obtained from the BMU 4, and the discharge is performed at the current value corresponding to the SOC range. Do. Further, during the discharge, the temperature of the storage battery 5 is measured for each SOC range sequentially using the information from the temperature measurement circuit 3, and the temperature of the storage battery 5 reaches the temperature upper limit value _TLIMIT , or when temperature increase is greater than the rise threshold ΔT of the battery 5 (step S208), the discharge is suppressed to a preset prescribed value I _min the current value for performing (step S209), the heat generation of the battery 5 is minimized Discharge so that When the temperature of the storage battery 5 becomes smaller than the preset temperature upper limit value T _{LIMIT due} to this discharge, or when the temperature rise amount of the storage battery 5 becomes smaller than the preset increase threshold value ΔT, each SOC range is again set. Is charged with a current value α _n I corresponding to (step S207). On the other hand, as a result of the determination in step S208, if the temperature of the storage battery 5 has not reached the temperature upper limit value _TLIMIT , or if the temperature increase amount of the storage battery 5 is smaller than the increase threshold value ΔT, the determination is first made in step S204. Discharge is performed at the current value α _n I, and the discharge is terminated when the SOC of the storage battery 5 reaches the lower limit SOC (step S211).

  FIG. 10 shows the secular change of the capacity maintenance rate when the storage battery 5 is operated by the charge / discharge control method shown in the present embodiment. In the conventional example, the storage battery temperature becomes large at the end of energization (the end of charging or the end of discharging), and the deterioration of the storage battery is large. When the storage battery 5 is operated by the control method, it becomes possible to suppress the storage battery temperature at the end of energization (the end of charge or the end of discharge), and the storage battery 5 does not deteriorate at the time of charge / discharge. The life of the storage battery 5 can be expected to be increased.

As described above, the charge / discharge control device 2 according to the present embodiment is a storage battery system 7 that includes the storage battery 5 that performs charge / discharge and the BMU 4 that is a storage battery management device that measures the SOC indicating the charge rate of the storage battery 5. It is a device that controls charging / discharging of the storage battery 5. The charge / discharge control device 2 divides the entire SOC from the minimum charging rate to the maximum charging rate of the storage battery 5 into a plurality of sections, and determines a plurality of SOC ranges, and for each SOC range, The current value determination unit 22 that determines the value of the current value for charging and discharging the storage battery, and the SOC range that includes the current SOC measured by the BMU 4 is obtained, and the storage battery is charged and discharged with the current value corresponding to the SOC range. and a discharge unit 23 for the current value determination section 22 sets a weighting factor alpha _n for each SOC range, for each SOC range by multiplying the weighting factor alpha _n to the reference current value I of the battery 5 The current value α _n I is determined. Here, the weighting coefficient α _n has the largest weighting coefficient value corresponding to the SOC range at the beginning of energization (initial stage of charging or discharging), and the weighting corresponding to the SOC range at the end stage of energization (end of charging period or end of discharging). The coefficient value is set to be the smallest. Thus, in the present embodiment, the charge / discharge control device 2 determines the current value at the time of charging / discharging weighted for each SOC range, and the initial energization of the storage battery 5 (initial charge or initial discharge). The current value is maximized and thereafter gradually decreased to minimize the current value at the end of energization (the end of charge or the end of discharge), thereby increasing the amount of heat generated from the initial energization to the middle energization of the storage battery 5. 5 can be prevented from degrading the performance at low temperatures, and the heat generation due to charging / discharging of the storage battery 5 at the end of energization can be prevented, so that the deterioration of the storage battery 5 can be prevented and the life of the storage battery 5 can be extended. .

In the present embodiment, the storage battery system 7 further includes a temperature measurement circuit 3 that measures the temperature of the storage battery 5. The charging / discharging unit 23 of the charging / discharging control device 2 has a current value α corresponding to the SOC range when the temperature of the storage battery 5 measured by the temperature measuring circuit 3 is equal to or higher than a preset temperature upper limit value T _{LIMIT. Since the} storage battery 5 is charged / discharged with a specified value I _min set to a value equal to or less than the current value α _n I corresponding to the SOC range instead of _n I, the deterioration of the storage battery 5 due to temperature rise is prevented. The life of the storage battery 5 can be further improved.

Furthermore, in the present embodiment, the charging / discharging unit 23 of the charging / discharging control device 2 is based on the temperature change of the storage battery 5 measured by the temperature measurement circuit 3 and the temperature increase amount of the storage battery 5 is set in advance. If it was threshold ΔT or more, instead of the current value alpha _{n I} corresponding to SOC range, charging of the storage battery 5 at a current value alpha _{n I} following values for the set specified value I _min corresponding to the SOC range Since the discharge is performed, deterioration due to the temperature rise of the storage battery 5 can be prevented, and the life of the storage battery 5 can be further improved.

Embodiment 2. FIG.
Hereinafter, an example of a simulation test of the charge / discharge control method shown in the first embodiment will be described.

  It shows about the charging method of the storage battery 5 whose usable temperature range is 10-40 degreeC and 30Ah. Initially, the charging current value is determined. Since a 30 Ah storage battery is assumed, it is assumed that charging is performed at 1 C (30 A (1 C is a current value at which charging can be completed in one hour)). This charging current value can be changed depending on the performance of the storage battery. If the chargeable time is clear, it is desirable to set it to a current value that can be terminated within that time. For example, if charging is possible for 3 hours, the life of the storage battery 5 can be further extended by setting 10 A (30 Ah / 3 h) as the reference current value.

  Next, consider a case where the SOC range width is assumed to be 10%. This range width can be arbitrarily determined. Next, the current value in each SOC range is determined. Since the reference current value 30A is determined, the SOC range in which charging is performed with the reference current value is determined. It is desirable to select an intermediate SOC range as much as possible as the reference SOC range. This time, based on the current value at SOC 40 to 50%, the current value in each SOC range is determined by the following equation (1).

In the expression (1), It is 30 Ah on the left side, α _{n on} the right side is a weighting coefficient of each SOC range, I is a reference current value, and t _n is a chargeable time in each SOC range. Since the current value of SOC is 40 to 50%, α ₅ = 1. In order to set the initial charge to the largest current, the magnitude of α _n is defined. Ideally, the current value at the initial stage of charging is set to be the largest, but it is important to set the current value so as not to adversely affect the life of the storage battery 5. Considering this point, the value of α ₁ is set to 1.4, and the value of α is decreased as the SOC decreases. From the conditional expression shown in the above formula (1), the value of α was set to decrease by 0.1. That is, α ₁₀ = 0.5 in the SOC range at the end of energization (SOC 90 to 100%). The current rate was determined considering the value of α. In this embodiment, since SOC 0 to 100% is divided into 10 parts, the charging time is exceeded, and in the case of even number division, the charging time when charging with reference current value I and the above method are used. An error occurs in the charging time due to the charged current. Therefore, it is necessary to correct the charging time. The corrected charging time is calculated for each SOC range with reference to the time to end with the reference current. Table 1 below shows the corrected charge / discharge time and current rate. Charging is performed according to Table 1. In the case of the odd division, the center SOC range is set to the reference current value (α ₅ = 1 in the case of 9 divisions), thereby eliminating the need for correction.

Next, the temperature of the storage battery 5 is measured, and if it is the usable temperature range of -10-40 degreeC, charge will be started. Here, the temperature upper limit value T _LIMIT of the storage battery 5 is set to T _LIMIT = 40 ° C., and the increase threshold ΔT with respect to the temperature increase amount of the storage battery 5 in each SOC range is set to ΔT = 10 ° C. This increase threshold value ΔT can be set freely. Thus, for each SOC range, the temperature of the storage battery 5 is monitored sequentially, the temperature increase amount of the storage battery 5 is less than the increase threshold ΔT = 10 ° C., and the temperature of the storage battery 5 is equal to the temperature upper limit value T _LIMIT = 40 ° C. If it does not exceed, charging is continued, and charging is terminated when the upper limit SOC is reached.

A case will be described in which the temperature rise amount of the storage battery 5 is the increase threshold ΔT = 10 ° C. or more, or the temperature of the storage battery 5 is the temperature upper limit value T _LIMIT = 40 ° C. or more. When the temperature increase amount in a certain SOC range is 10 ° C. or higher, or the temperature of the storage battery 5 is 40 ° C. or higher, the current value in the SOC range next to the SOC range is set to the heat generation of the storage battery 5. The small current value is set to about 15 A (about 0.5 C), and the temperature rise of the storage battery 5 is suppressed. Thus, when the temperature increase amount of the storage battery 5 in the next SOC range is less than the increase threshold and the temperature of the storage battery 5 is equal to or lower than the temperature upper limit value 40 ° C., each SOC determined first with reference to the current SOC range Charging is performed according to the current value α _n I corresponding to the range.

For example, as shown in FIG. 7, in a range of SOC 20 to 30% and SOC 50 to 60% after starting charging, the temperature increase amount of the storage battery 5 is 10 ° C. or more, or the temperature of the storage battery 5 is a temperature. Assume that the upper limit of 40 ° C is exceeded. That is, dT / dSOC> 10 ° C. or the cell temperature Tsoc ₃ > 40 ° C. when the SOC reaches 30%. In this case, charging is performed at the current value calculated according to Table 1 until SOC = 0 to 30%, but the current value is set to a current value 15A that can suppress the heat generation of the storage battery 5 at SOC = 30 to 40%. To charge the battery and lower the storage battery temperature. In the range of SOC = 30 to 40% where the current is limited, if the temperature rise is 10 ° C or less and the storage battery temperature upper limit value is 40 ° C, the SOC 40 to 50% or later is charged with the current value of Table 1. Do. Similarly, it is assumed that the temperature rise amount in the range of SOC = 50 to 60% exceeds 10 ° C. or exceeds the storage battery temperature upper limit 40 ° C. That is, dT / dSOC> 10 ° C., or the cell temperature Tsoc ₆ > 40 ° C. when the SOC reaches 50%. Charging is performed by setting the current value of SOC = 60 to 70% to a current value 15A that can suppress the heat generation of the storage battery 5, and the storage battery temperature is lowered. When the temperature rise amount is 10 ° C. or less and the storage battery temperature upper limit value is 40 ° C. within the range of SOC 50 to 60% in which the current is limited, charging is performed at the current value shown in Table 1 after SOC 70 to 80%. Thereafter, when the upper limit SOC is reached, charging is terminated.

  Next, the case where it is determined that the battery is discharged rather than charged will be described. Similarly to the charging, a 30 Ah storage battery is assumed, and therefore, it is assumed that the discharging current value is discharged at 1 C (30 A (1 C is a current value at which discharging can be completed in one hour)). The discharge current value can be changed depending on the performance of the storage battery. If the dischargeable time is clear, it is desirable to set the discharge current value to a current value that can be finished within that time. For example, if discharge is possible for 3 hours, the life of the storage battery can be further extended by setting 10 A (30 Ah / 3 h) as the reference current value.

  Next, consider the case where the SOC range is assumed to be 10% as in the case of charging. This range can be arbitrarily determined. Next, the discharge current value in each SOC range is determined. Since the reference current value 30A is determined, the SOC range in which discharge is performed is determined based on the reference current value. It is desirable to select an intermediate SOC range as much as possible as the reference SOC range. This time, the current value in each SOC range is determined by the following equation using the current value at SOC 40 to 50% as a reference.

In the equation (2), It is 30 Ah on the left side, α _{n on} the right side is a weighting coefficient for each SOC range, I is a reference current value, and t _n is a chargeable time in each SOC range. Since the current value of SOC is 40 to 50%, α ₆ = 1. In order to set the initial stage of discharge to the largest current, the magnitude of α _n is defined. Ideally, the current value at the initial stage of discharge is set to be the largest, but it is important to set the current value so as not to adversely affect the life of the storage battery. In consideration of this point, the value of α1 is 1.5, with the SOC decreases, reducing the value of alpha _n. From the above conditional expression, it was set to decrease by 0.1. That is, α ₁₀ = 0.6. The current rate was determined considering the value of α. In this embodiment, since SOC 0 to 100% is divided into 10 parts, the discharge time is exceeded, and in the case of even divisions, the charge time when discharging at the reference current value and the discharge calculated by the above method An error occurs in the discharge time due to the current. Therefore, it is necessary to correct the discharge time. The corrected discharge time is calculated in each SOC range with reference to the time to end with the reference current. Table 2 shows the corrected discharge time and current rate. Charging is performed according to Table 2. In the case of the odd division, the center SOC range is set to the reference current value (α ₅ = 1 in the case of 9 divisions), thereby eliminating the need for correction.

Next, the temperature of the storage battery 5 is measured, and if it is the usable temperature range of -10-40 degreeC, discharge will be started. Here, the temperature upper limit value of the storage battery 5 is T _LIMIT = 40 ° C., and the rising threshold value for the temperature increase amount of the storage battery 5 in each SOC range is ΔT = 10 ° C. This increase threshold value ΔT can be set freely. Sequentially monitor the temperature of the storage battery 5 and continue discharging if the temperature rise in the SOC range does not exceed 10 ° C and the temperature of the storage battery 5 does not exceed the upper temperature limit of 40 ° C. When the lower limit SOC is reached, the discharge is terminated.

The case where the temperature rise amount of the storage battery 5 is equal to or higher than the increase threshold value ΔT or the temperature of the storage battery 5 exceeds the temperature upper limit value will be described. When the temperature rise amount in a certain SOC range is 10 ° C. or more and the temperature of the storage battery 5 exceeds the temperature upper limit value 40 ° C., the current value in the SOC range next to the SOC range is reduced, and the heat generation of the storage battery 5 is small. The current value is set to about 15 A (about 0.5 C), and the temperature rise of the storage battery 5 is suppressed. As a result of the discharge, if the temperature rise amount in the next SOC range is less than the rise threshold ΔT and the cell temperature is less than the upper temperature limit value of 40 ° C., the current SOC is referred to and each SOC range determined first is set. Discharging is performed according to the corresponding current value α _n I.

For example, as shown in FIG. 8, when discharge is started, the temperature rise in the SOC 80 to 70% range and the SOC 50 to 40% range exceeds 10 ° C. or exceeds the storage battery temperature upper limit 40 ° C. Assume a case. That is, dT / dSOC> 10 ° C., or the temperature Tsoc ₃ > 40 ° C. of the storage battery 5 when the SOC reaches 70%. In this case, SOC 100 to 70% is discharged with the current value calculated according to Table 2, but the current value of SOC 70 to 60% is set to a current value 15A that can suppress the heat generation of the storage battery 5 and charging is performed. Reduce the storage battery temperature. When the temperature rise is less than 10 ° C. and the storage battery temperature upper limit value is 40 ° C. within the range of SOC 70 to 60% in which the current is limited, charging is performed at the current value shown in Table 2 after SOC 60 to 50%. Similarly, the case where the temperature rise amount in the range of SOC 50 to 40% is 10 ° C. or higher, or the temperature of the storage battery 5 exceeds the temperature upper limit value 40 ° C. is assumed. That is, dT / dSOC> 10 ° C., or the storage battery temperature Tsoc ₆ > 40 ° C. when the SOC reaches 50%. Charging is performed by setting the current value of SOC 40 to 30% to a current value 15A that can suppress the heat generation of the storage battery, and the storage battery temperature is lowered. In the SOC range of SOC 30 to 30% with limited current, if the temperature rise is 10 ° C or less and the storage battery temperature upper limit value 40 ° C is below 40 ° C, discharge is performed at the current value shown in Table 2 until SOC 30 to 0%. Do. Thereafter, when the lower limit SOC is reached, the discharge is terminated.

As described above, also in the present embodiment, as in the first embodiment, the charging / discharging control device 2 determines the current value during charging / discharging by weighting each SOC range, and Energizing from the initial energization of the storage battery 5 by increasing the current value at the beginning of energization (initial stage of charging or discharging) and then gradually decreasing it to minimize the current value at the end of energizing period (end of charging or end of discharging). The amount of heat generated in the middle period is increased to prevent the performance of the storage battery 5 from being lowered at a low temperature, and the deterioration of the storage battery 5 can be prevented by suppressing the heat generation due to charging / discharging of the storage battery 5 at the end of energization. 5 can be extended in service life.
Also in the second embodiment, as in the first embodiment, when the temperature of the storage battery 5 exceeds the limit during charging / discharging with the above-described weighted current value, a current value for charging / discharging is set in advance. Since the charging and discharging are continued while cooling the storage battery 5 while being limited to the specified value _Imin , the deterioration due to the temperature rise of the storage battery 5 can be prevented, and the life of the storage battery 5 can be further improved.

  In the first and second embodiments, the example in which two “restrictions” on the temperature of the storage battery 5 are provided, that is, the condition 1 and the condition 2. However, the present invention is not limited to this, and the conditions 1 and 2 Only one of them may be provided as “restriction”. Alternatively, the number of conditions may be three or more by adding other conditions without setting the number of conditions to two or less.

  DESCRIPTION OF SYMBOLS 1 Power supply, 2 Charging / discharging control apparatus, 3 Temperature measurement circuit, 4 BMU (battery management unit), 5 Storage battery, 6 Load, 7 Storage battery system, 21 SOC range determination part, 22 Current value determination part, 23 Charging / discharging part.

Claims (5)

A charge / discharge control device for controlling charge / discharge of the storage battery in a storage battery system comprising a storage battery that performs charge / discharge and a storage battery management device that measures an SOC indicating a charge rate of the storage battery,
An SOC range determination unit that divides the entire SOC from the minimum charging rate to the maximum charging rate of the storage battery into a plurality of sections and determines a plurality of SOC ranges;
For each SOC range, a current value determining unit that determines a current value for charging and discharging the storage battery;
A charge / discharge unit that obtains the SOC range including the current SOC measured by the storage battery management device, and charges and discharges the storage battery at the current value corresponding to the SOC range;
The current value determining unit sets a weighting coefficient for each of the SOC ranges, multiplies a reference current value by the weighting coefficient to determine the current value for each of the SOC ranges,
The weighting coefficient is set so that the weighting coefficient value corresponding to the SOC range at the beginning of charging / discharging is the largest, then gradually decreasing, and the weighting coefficient value corresponding to the SOC range at the end of charging / discharging becomes the smallest. And
During discharge, the discharge current at the beginning of discharge is the largest, and then the discharge current gradually decreases as the SOC value decreases.
Charge / discharge control device. The storage battery system further includes a temperature measurement circuit that measures the temperature of the storage battery,
When the temperature of the storage battery measured by the temperature measurement circuit is equal to or higher than a preset temperature upper limit value, the charging / discharging unit replaces the current value corresponding to the SOC range with the SOC range. The charge / discharge control device according to claim 1, wherein the storage battery is charged / discharged with a current regulation value set to a value equal to or less than the current value corresponding to. The storage battery system further includes a temperature measurement circuit that measures the temperature of the storage battery,
The charging / discharging unit corresponds to the SOC range when a temperature increase amount of the storage battery is equal to or higher than a preset increase threshold based on a temperature change of the storage battery measured by the temperature measurement circuit. The charge / discharge control device according to claim 1, wherein the storage battery is charged / discharged with a current regulation value set to a value equal to or less than the current value corresponding to the SOC range instead of the current value. The storage battery system further includes a temperature measurement circuit that measures the temperature of the storage battery,
The charging / discharging unit is configured such that the temperature of the storage battery measured by the temperature measurement circuit is equal to or higher than a preset temperature upper limit value, or the temperature increase amount of the storage battery is equal to or higher than a preset increase threshold value. The charge / discharge control according to claim 1, wherein the storage battery is charged / discharged with a current regulation value set to a value equal to or less than the current value corresponding to the SOC range instead of the current value corresponding to the SOC range. apparatus. A charge / discharge control method for controlling charge / discharge of the storage battery in a storage battery system comprising a storage battery that performs charge / discharge and a storage battery management device that measures an SOC indicating a charge rate of the storage battery,
An SOC range determining step for determining a plurality of SOC ranges by dividing the entire SOC from the minimum charging rate to the maximum charging rate of the storage battery into a plurality of sections;
A current value determining step for determining a current value for charging and discharging the storage battery for each SOC range by setting a weighting coefficient for each SOC range and multiplying the reference current value by the weighting coefficient;
A charge / discharge step of obtaining the SOC range including the current SOC measured by the storage battery management device, and charging / discharging the storage battery with the current value corresponding to the SOC range; and
The weighting coefficient is set such that the weighting coefficient value corresponding to the SOC range at the beginning of charging / discharging is the largest, then gradually decreases, and the weighting coefficient value corresponding to the SOC range at the end of charging / discharging becomes the smallest. ,
During discharge, the discharge current at the beginning of discharge is the largest, and then the discharge current gradually decreases as the SOC value decreases.
Charge / discharge control method.

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