JP7043948B2 - Power system - Google Patents

Description

The present invention relates to a power supply system including a battery module in which a plurality of secondary batteries are connected in parallel and a control unit for controlling charging / discharging of the battery module.

Conventionally, a power supply system including a battery module in which a plurality of secondary batteries are connected in parallel and a control unit for controlling charging / discharging of the battery module has been known. In this power supply system, relays are provided in each secondary battery (see FIG. 21). The control unit controls the on / off operation of these relays. This is configured to control the charging and discharging of the secondary battery.

It is known that when the battery module is discharged, the SOC (state of charge) varies due to the variation in the internal resistance of each secondary battery. That is, since the secondary battery having a small internal resistance is easily discharged, the SOC is likely to decrease. Further, since the secondary battery having a large internal resistance is hard to discharge, the SOC is hard to decrease. When the SOC varies in this way, a large current flows from the secondary battery having a high SOC (that is, the voltage is high) to the secondary battery having a low SOC (that is, the voltage is low) when the discharge is completed. Therefore, it is conceivable that problems such as melting of the relay may occur.

In order to solve this problem, it has been studied to provide a equalization circuit for equalizing the SOC of the secondary battery in the battery module (see Patent Document 1 below).

Japanese Patent No. 5772708

However, if the equalization circuit is provided, the circuit configuration of the power supply system tends to be complicated. Therefore, the manufacturing cost of the power supply system tends to increase. Further, a resistor is installed in the equalization circuit so that a large current does not flow from the secondary battery having a high SOC to the secondary battery having a low SOC. Therefore, the resistance causes wasteful power consumption.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power supply system capable of equalizing the SOCs of a plurality of secondary batteries and simplifying a circuit configuration.

One aspect of the present invention is a battery module (4) in which a plurality of series bodies (10) having a secondary battery (2) and a relay (3) connected in series to the secondary battery are connected in parallel to each other. )When,
A control unit (5) for controlling charging / discharging of the battery module is provided.
The control unit
The SOC estimation unit (50) that estimates the SOC of each of the above secondary batteries, and
A discharge indicator (51) that discharges the electric charge stored in the plurality of secondary batteries to the load (6) by turning on the plurality of the relays.
Based on the SOC estimated by the SOC estimation unit, among the plurality of secondary batteries discharged to the load, the relays of some of the secondary batteries are turned off, so that the plurality of secondary batteries are discharged. It is provided with an equalization processing unit (52) for equalizing the SOC of the next battery.
The control unit is an individual when the power prediction unit (53) that predicts the electric energy (W) consumed by the load and the power prediction unit (53) have completed the supply of the electric energy to the load while equalizing the SOC. Further, the SOC prediction unit (54) for calculating the predicted SOC which is the predicted value of the SOC of the secondary battery is further provided, and the equalization processing unit uses the estimated value of the SOC by the SOC estimation unit as the predicted SOC. The power system (1) is configured to turn off the relay in order from the reached secondary battery .

The control unit of the power supply system includes the equalization processing unit. The equalization processing unit turns off the relay of some of the plurality of discharging secondary batteries based on the estimated SOC. This equalizes the SOC of the secondary battery.
Therefore, the SOC can be equalized without providing a special circuit such as an equalization circuit, and the circuit configuration of the power supply system can be simplified. Further, since there is no power consumption due to the resistance included in the equalization circuit, the power of the secondary battery can be effectively used.

As described above, according to the above aspect, it is possible to provide a power supply system capable of equalizing the SOCs of a plurality of secondary batteries and simplifying the circuit configuration.
The reference numerals in parentheses described in the scope of claims and the means for solving the problem indicate the correspondence with the specific means described in the embodiments described later, and limit the technical scope of the present invention. It's not a thing.

Further, the above-mentioned "equalization" means reducing the variation in SOCs of a plurality of secondary batteries, and is not limited to the meaning of making the SOCs completely equal.

The circuit diagram of the power supply system in Embodiment 1. The operation explanatory diagram of the power-source system in Embodiment 1. The figure following FIG. The figure following FIG. The figure following FIG. The flowchart of the control unit in Embodiment 1. OCV-SOC characteristics in Embodiment 1. FIG. 6 is a cross-sectional view of a battery cell having approximately 100% SOC in the first embodiment. FIG. 6 is a cross-sectional view of a battery cell having a SOC of about 0% in the first embodiment. The side view of the refrigerator truck in Embodiment 1. The graph which showed the time change of the temperature of the freezer in Embodiment 1. The circuit diagram of the power supply system in Embodiment 2. The flowchart of the control unit in Embodiment 2. OCV-SOC characteristics in Embodiment 2. The circuit diagram of the power supply system in Embodiment 3. The flowchart of the control unit in Embodiment 3. The flowchart following FIG. The circuit diagram of the power supply system in Embodiment 4. The flowchart of the control unit in Embodiment 4. The flowchart following FIG. An operation explanatory diagram of a power supply system in a comparative form.

(Embodiment 1)
An embodiment of the power supply system will be described with reference to FIGS. 1 to 11. As shown in FIG. 1, the power supply system 1 of the present embodiment includes a battery module 4 and a control unit 5. The battery module 4 is formed by connecting a plurality of series bodies 10 having a secondary battery 2 and a relay 3 connected in series to the secondary battery 2 in parallel with each other. The control unit 5 controls the charging / discharging of the battery module 4.

The control unit 5 includes an SOC estimation unit 50, a discharge instruction unit 51, and a equalization processing unit 52. The SOC estimation unit 50 estimates the SOC of each secondary battery 2. The discharge instruction unit 51 turns on a plurality of relays 3 (see FIG. 2). As a result, the electric charges stored in the plurality of secondary batteries 2 are discharged to the load 6.

The equalization processing unit 52 turns off the relay 3 of some of the secondary batteries 2 discharged to the load 6 based on the SOC estimated by the SOC estimation unit 50 (the equalization processing unit 52 turns off the relay 3 of some of the secondary batteries 2 discharged to the load 6. (See FIGS. 3 to 5). As a result, the SOCs of the plurality of secondary batteries 2 are equalized.

As shown in FIG. 1, the secondary battery 2 is composed of a plurality of battery cells 20. The secondary battery 2 is provided with a voltage sensor 7 _V and a current sensor 7 _I. Further, the load 6 and the charging device 11 are connected to the battery module 4. A discharge switch 12 is interposed between the load 6 and the battery module 4. A charging switch 13 is interposed between the charging device 11 and the battery module 4. When the battery module 4 is discharged, the control unit 5 turns on the discharge switch 12 and each relay 3. Further, when charging the battery module 4, the charging switch 13 and each relay 3 are turned on.

As shown in FIG. 10, the power supply system 1 of this embodiment is used for the refrigerator truck 14. The freezer truck 14 is provided with a freezer 61. In this embodiment, the battery module 4 is used to drive the compressor (load 6) of the freezer 61 to lower the temperature inside the freezer 61.

While the refrigerator truck 14 is running, the engine operates a mechanical compressor to lower the temperature inside the refrigerator. Further, when loading and unloading the luggage, the engine is stopped and the electric compressor is operated by the battery module 4.

As shown in FIG. 11, since the mechanical compressor operates during traveling, the temperature is maintained at a low temperature. If you open the door when loading and unloading luggage, the temperature will rise due to the outside air. After that, when the door is closed and the luggage is carried in and out of the store, the electric compressor operates and the temperature drops.

As shown in FIG. 10, the freezer 61 is provided with a temperature sensor 7 _T. From the temperature of the freezer 61 measured by the temperature sensor 7 _T , it is possible to predict the amount of electric power W required to lower the temperature to the target temperature.

As shown in FIG. 1, the control unit 5 includes a power prediction unit 53, an SOC prediction unit 54, and a storage unit 55 in addition to the SOC estimation unit 50 and the like. The electric power prediction unit 53 predicts the electric energy W consumed by the compressor (load 6) by using the measured value of the temperature of the freezer 61. Further, the SOC prediction unit 54 calculates the predicted SOC, which is the predicted value of the SOC of each secondary battery 2 when the supply of the electric energy W to the load 6 is completed while equalizing the SOC. The storage unit 55 stores the relationship between the OCV (Open Circuit Voltage) and the SOC of the secondary battery 2 (OCV-SOC characteristics: see FIG. 7).

When the temperature of the freezer 61 is lowered, the control unit 5 turns on a plurality of relays 3 as shown in FIG. Since the internal resistance of the secondary battery 2 varies, as shown in FIG. 3, the secondary battery _2a having the smallest internal resistance has a rapid decrease in SOC. When the SOC of the secondary battery _2a reaches the predicted SOC, the equalization processing unit 52 turns off the relay _3a of the secondary battery _2a . When discharging is continued in this state, the SOC of the secondary battery 2 _b , which has the second smallest internal resistance, reaches the predicted SOC as shown in FIG. At this time, the equalization processing unit 52 turns off the relay 3 _b of the secondary battery 2 _b . When the discharge is continued, as shown in FIG. 5, the SOC of the secondary battery _2c having the largest internal resistance reaches the predicted SOC. At this time, the equalization processing unit 52 turns off the relay _3c of the secondary battery _2c . As a result, the SOCs of all the secondary batteries _2a to _2c are equalized.

Next, the structure of the battery cell 20 will be described. In this embodiment, a lithium ion secondary battery is used as the battery cell 20. As shown in FIG. 8, the battery cell 20 includes a pair of electrodes 23 (positive electrode 23 _P and negative electrode 23 _N ), a separator 24 interposed between them, and an electrolytic solution 25. The electrode 23 includes a collecting electrode 21 and an active material 22 into which lithium ions are inserted and removed. As shown in FIG. 8, when the electric discharge is performed, the lithium ions are desorbed from the negative electrode active material 22 _N , move the electrolytic solution 25, and are inserted into the positive electrode active material 22 _P.

Further, as shown in FIG. 9, when charging is performed, lithium ions are desorbed from the positive electrode active material 22 _P , move the electrolytic solution 25, and are inserted into the negative electrode active material 22 _N.

FIG. 7 shows the OCV-SOC characteristics of the secondary battery 2. As described above, this OCV-SOC characteristic is stored in the storage unit 55 (see FIG. 1). The SOC estimation unit 50 estimates the SOC of the secondary battery 2 using this OCV-SOC characteristic. That is, if the secondary battery 2 is not charged and discharged for a while, the voltage of the secondary battery 2 becomes stable and the OCV can be measured. When this state is reached, OCV is measured using the voltage sensor 7 _V (see FIG. 1), and the SOC corresponding to the measured value is estimated from the OCV-SOC characteristics.

Further, when the secondary battery 2 is discharged, the SOC of the secondary battery 2 is lowered. The SOC of the secondary battery 2 being discharged can be estimated as follows, for example. That is, first, the OCV is measured in a state where the secondary battery 2 has not been charged / discharged for a while, and the measured value is used to calculate the SOC _ini before discharging. Then, the SOC during discharge can be calculated from the current I of the secondary battery 2 being discharged, the discharge time t, and the capacity C of the secondary battery 2 by using the following formula.
SOC = SOC _ini -Δ SOC
= SOC _ini -It / C

Next, the flowchart of the control unit 5 will be described. FIG. 6 shows a flowchart for performing the operations of FIGS. 2 to 4. As shown in FIG. 6, the control unit 5 first performs step S1. Here, the electric energy W consumed by the load 6 (that is, the compressor) is predicted. After that, the process proceeds to step S2, and the current SOC of each secondary battery 2 is estimated.

Next, the process proceeds to step S3, and the predicted SOC (that is, the predicted value of the SOC of each secondary battery 2 when the supply of the electric energy W to the load 6 is completed while equalizing the SOC) is calculated. The predicted SOC can be calculated using, for example, the following formula.
Prediction SOC = SOC _ini -ΔW / W _FULL
ΔW = W / N
In the above formula, SOC _ini is the SOC of the secondary battery 2 before discharge, ΔW is the amount of power discharged by each secondary battery 2, and W _FULL is the energy of the secondary battery 2 when fully charged. It is a quantity, and N is the number of secondary batteries 2 connected in parallel.

After step S3, the process proceeds to step S4 to start discharging the battery module 4. After that, the process proceeds to step S5. Here, it is determined whether or not the secondary battery 2 that has reached the predicted SOC exists. If it is determined to be Yes here, the process proceeds to step S6, and the relay 3 of the secondary battery 2 that has reached the predicted SOC is turned off.

After that, the process proceeds to step S7. Here, it is determined whether or not all the relays 3 have been turned off. If No is determined here, the process returns to step S5. If it is determined to be Yes, the process ends.

The action and effect of this embodiment will be described. As shown in FIG. 1, the control unit 5 of the present embodiment includes an equalization processing unit 52. As shown in FIGS. 2 to 5, the equalization processing unit 52 turns off the relay 3 of some of the plurality of discharged secondary batteries 2 based on the estimated SOC. .. As a result, the SOC of the secondary battery 2 is equalized.
Therefore, the SOC can be equalized without providing a special circuit such as an equalization circuit, and the circuit configuration of the power supply system 1 can be simplified. Therefore, the manufacturing cost of the power supply system 1 can be reduced. Further, since the equalization is completed when the discharge is completed, the number of operations of the relay 3 can be minimized. Therefore, it is possible to suppress the shortening of the life of the relay 3.

That is, as shown in FIGS. 21 (A) and 21 (B), if the SOC is not equalized, the SOC of the secondary battery _2a having a small internal resistance drops rapidly. Therefore, after stopping the discharge, as shown in FIG. 21 (C), from the secondary batteries 2 _b and 2 _c with high SOC (that is, the secondary battery 2 with high voltage) to the secondary battery 2 _a with low SOC (that is, the secondary battery 2 a with high voltage). That is, a large current flows through the secondary battery 2) having a low voltage. Therefore, it is conceivable that a problem such as melting of the relay 3 may occur. In order to solve this problem, conventionally, a dedicated circuit (equalization circuit) for equalizing the SOC has been provided, but if this is done, the circuit configuration of the power supply system 1 becomes complicated, and the power supply system 1 becomes complicated. Manufacturing costs tend to be high. On the other hand, in the present embodiment, among the plurality of secondary batteries 2 being discharged, the relay 3 of some of the secondary batteries 2 is turned off and the discharge of the other secondary batteries 2 is continued to perform SOC. Is equalized. Therefore, it is not necessary to provide a special equalization circuit, and the circuit configuration of the power supply system 1 can be simplified. Moreover, the manufacturing cost of the power supply system 1 can be reduced.

Further, as shown in FIG. 1, the control unit 5 of the present embodiment further includes a power prediction unit 53 that predicts the electric energy W consumed by the load 6 and an SOC prediction unit 54 that calculates the predicted SOC. As shown in FIG. 6, the equalization processing unit 52 is configured to turn off the relay 3 in order from the secondary battery 2 whose estimated SOC reaches the predicted SOC (steps S5 and S6).
In this way, the SOC (predicted SOC) of each secondary battery 2 when the electric energy W is supplied to the load 6 is predicted, and the relay 3 of the secondary battery 2 that has reached this predicted SOC is turned off. 3 can be turned off at the optimum timing. Therefore, the SOC can be equalized with high accuracy.

Further, as shown in FIG. 10, the load 6 of this embodiment is a compressor of the freezer 61. A temperature sensor 7 _T is provided in the freezer 61. The electric power prediction unit 53 is configured to predict the electric energy W based on the measured value of the temperature of the freezer 61.
In this way, the amount of power W consumed can be predicted with high accuracy. Therefore, the predicted SOC of each secondary battery 2 can be calculated accurately, and the SOC can be equalized with high accuracy. Further, the number of operations of the relay 3 can be minimized, and the life of the relay 3 can be shortened.

As described above, according to this embodiment, it is possible to provide a power supply system capable of equalizing the SOCs of a plurality of secondary batteries and simplifying the circuit configuration.

(Embodiment 2)
This embodiment is an example in which the configuration of the control unit 5 is changed. As shown in FIG. 12, the control unit 5 of the present embodiment includes the SOC estimation unit 50 to the storage unit 55, as in the first embodiment. In addition to these, the control unit 5 includes a non-blocking SOC prediction unit 56 and an off stop command unit 57. The storage unit 55 stores OCV-SOC characteristics as in the first embodiment. The non-disruptive SOC prediction unit 56 predicts the SOC of each secondary battery 2 as the non-disruptive SOC when the supply of the electric energy W to the load 6 is completed without turning off any of the plurality of relays 3. .. Further, the off stop command unit 57 calculates the slope ΔOCV / ΔSOC of the OCV-SOC characteristic in the non-blocking SOC of each secondary battery 2. When the inclination of all the secondary batteries 2 is smaller than the predetermined threshold value _ΔTH , the equalization processing unit 52 stops the off processing of the relay 3.

FIG. 14 shows an example of OCV-SOC characteristics in this embodiment. As shown in the figure, the secondary battery 2 of the present embodiment has a region (low fluctuation region A) in which the OCV hardly changes even if the SOC changes. Depending on the type of the active material 22 (see FIG. 8), such characteristics may be exhibited. If the SOCs of all the secondary batteries 2 are present in the low fluctuation region A when the relay 3 is not turned off, a large voltage is not generated between the plurality of secondary batteries 2 when the discharge is completed. .. Therefore, there is no problem that a large current flows from the secondary battery 2 having a high SOC to the secondary battery 2 having a low SOC. In this embodiment, in this case, the process of turning off the relay 3 of the secondary battery 2 being discharged to equalize the SOC is stopped.

Next, the flowchart of the control unit 5 in this embodiment will be described. As shown in FIG. 13, the control unit 5 first performs steps S1 to S4 in the same manner as in the first embodiment. In this embodiment, after step S4, the process proceeds to step S11. Here, the non-blocking SOC is calculated. Then, the process proceeds to step S12. In step S12, the slope ΔOCV / ΔSOC of each secondary battery 2 in the non-blocking SOC is calculated.

Then, the process proceeds to step S13. Here, it is determined whether or not there is a secondary battery 2 whose inclination exceeds the threshold value Δ _TH . If it is determined that Yes (that is, there is a secondary battery 2 having a large inclination), the process proceeds to step S5 of the first embodiment. If it is determined that No (that is, the secondary battery 2 having a large inclination does not exist), the process proceeds to step S14. Here, it is determined whether or not the planned electric energy W has been supplied to the load 6. If it is determined to be Yes here, all relays 3 are turned off.

Next, the action and effect of this embodiment will be described. As described above, in this embodiment, the slope ΔOCV / ΔSOC of the OCV-SOC characteristic in the non-blocking SOC of each secondary battery 2 is calculated. When the inclination of all the secondary batteries 2 is smaller than the predetermined threshold value _ΔTH , the equalization processing unit 52 stops the off processing of the relay 3.
By doing so, the load 6 is less likely to be operated by only a part of the secondary batteries 2, and it is possible to suppress the flow of a large current through the secondary batteries 2. Therefore, it is possible to prevent the secondary battery 2 from suddenly deteriorating.
In addition, it has the same configuration and action as in the first embodiment.

(Embodiment 3)
This embodiment is an example in which the configuration of the control unit 5 is changed. As shown in FIG. 15, the control unit 5 of the present embodiment includes the SOC estimation unit 50 to the storage unit 55, as in the first embodiment. In addition to these, the control unit 5 includes an off stop command unit 57 and a current prediction unit 58. The current prediction unit 58 determines the current I of each secondary battery 2 other than the reaching secondary battery 2 _Z when the relay 3 of the reaching secondary battery 2 _Z , which is the secondary battery 2 that has reached the predicted SOC, is turned off. Predict. The off stop command unit 57 turns off the relay 3 of the reached secondary battery 2 _Z by the equalization processing unit 52 when there is a secondary battery 2 in which the predicted current I exceeds a predetermined threshold value I _TH . Cancel the process.

When the relay 3 of the reaching secondary battery 2 _Z is turned off, the number of the secondary batteries 2 that can supply the current I to the load 6 decreases. Therefore, the current I of each secondary battery 2 increases. In this embodiment, when the relay 3 of the reaching secondary battery 2 _Z is temporarily turned off, the current I of the other secondary battery 2 is predicted, and when the current I larger than the threshold value I _TH flows, the secondary battery 2 Do not turn off the relay 3 of the reaching secondary battery 2 _Z because the life is likely to be shortened and the relay 3 is likely to be melted.

Next, the flowchart of the control unit 5 will be described with reference to FIGS. 16 and 17. As shown in FIG. 16, the control unit 5 of the present embodiment first performs steps S1 to S5 as in the first embodiment. Then, after step S5, step S21 is performed. Here, the current I of the remaining secondary battery 2 after the relay 3 of the reaching secondary battery 2 _Z is turned off is predicted.

After that, the process proceeds to step S22. Here, it is determined whether or not there is a secondary battery 2 in which the predicted current I exceeds the threshold value I _TH . If it is determined to be Yes (that is, if it is determined that a large current flows through the other secondary battery 2 when the relay 3 of the reaching secondary battery 2 _Z is turned off), the process proceeds to step S23. In step S23, it is determined whether or not the planned electric energy W has been supplied to the load 6. If it is determined to be Yes here, the process proceeds to step S24, and all relays 3 are turned off.

If it is determined as No in step S22 (that is, if it is determined that a large current does not flow to the other secondary battery 2 even if the relay 3 of the reaching secondary battery 2 _Z is turned off), the process is performed in step S25. Move. Then, the relay 3 of the reaching secondary battery 2 _Z is turned off. After that, the process proceeds to step S26, and it is determined whether or not all the relays 3 have been turned off. If Yes is determined here, the process ends, and if No is determined, the process returns to step S5.

The action and effect of this embodiment will be described. With the above configuration, when the relay 3 of the reaching secondary battery 2 _Z is turned off, a large current flows through the remaining secondary battery 2, and it is possible to suppress a problem that the life of the secondary battery 2 is shortened.
In addition, it has the same configuration and action as in the first embodiment.

(Embodiment 4)
This embodiment is an example in which the configuration of the control unit 5 is changed. As shown in FIG. 18, the control unit 5 of the present embodiment includes the SOC estimation unit 50 to the storage unit 55, as in the first embodiment. In addition to these, the control unit 5 includes an off stop command unit 57 and a voltage prediction unit 59. The voltage prediction unit 59 turns off the relay 3 of the secondary battery 2 (that is, the reaching secondary battery 2 _Z ) that has reached the predicted SOC, and the voltage of each secondary battery 2 other than the reaching secondary battery 2 _Z. Predict V. When the secondary battery 2 whose predicted voltage is lower than the predetermined threshold value V _TH exists, the off stop command unit 57 performs the off processing of the relay 3 of the reaching secondary battery 2 _Z by the equalization processing unit 52. Abort.

When the relay 3 of the reaching secondary battery 2 _Z is turned off, as described above, the number of the secondary batteries 2 that can supply the current I to the load 6 decreases, and the current I of each secondary battery 2 increases. Since the voltage V (that is, CCV: Closed Circuit Voltage) of the secondary battery 2 can be expressed by the following equation, if the current I increases too much, the CCV may decrease and the secondary battery 2 may deteriorate. Conceivable. Therefore, in this case, the relay 3 of the reaching secondary battery 2 _Z is not turned off.
CCV = OCV-IR

Next, the flowchart of the control unit 5 will be described with reference to FIGS. 19 and 20. As shown in FIG. 19, the control unit 5 of the present embodiment first performs steps S1 to S5 as in the first embodiment. Then, after performing step S5, step S31 is performed. Here, the voltage V of the remaining secondary battery 2 after the relay 3 of the reaching secondary battery 2 _Z is turned off is predicted.

After that, the process proceeds to step S32. Here, it is determined whether or not there is a secondary battery 2 whose predicted voltage V is lower than the threshold value V _TH . If it is determined that Yes (that is, when the relay 3 of the reaching secondary battery 2 _Z is turned off, the voltage V of the other secondary battery 2 drops significantly), the process proceeds to step S33. In step S33, it is determined whether or not the planned electric energy W has been supplied to the load 6. If it is determined to be Yes here, the process proceeds to step S34 and all relays 3 are turned off.

If it is determined in step S32 that No (that is, even if the relay 3 of the reaching secondary battery 2 _Z is turned off, the voltage V of the other secondary battery 2 does not drop significantly), the process proceeds to step S35. Then, the relay 3 of the reaching secondary battery 2 _Z is turned off. After that, the process proceeds to step S36, and it is determined whether or not all the relays 3 have been turned off. If Yes is determined here, the process ends, and if No is determined, the process returns to step S5.

The action and effect of this embodiment will be described. With the above configuration, when the relay 3 of the reaching secondary battery 2 _Z is turned off, the voltage V of the remaining secondary battery 2 drops significantly, and it is possible to suppress the problem that the secondary battery 2 tends to deteriorate.
In addition, it has the same configuration and action as in the first embodiment.

The present invention is not limited to each of the above embodiments, and can be applied to various embodiments without departing from the gist thereof.

1 Power supply system 10 Series 2 Secondary battery 3 Relay 4 Battery module 5 Control unit 50 SOC estimation unit 51 Discharge indicator 52 Equalization processing unit

Claims (5)

A battery module (4) in which a plurality of series bodies (10) having a secondary battery (2) and a relay (3) connected in series to the secondary battery are connected in parallel to each other, and a battery module (4).
A control unit (5) for controlling charging / discharging of the battery module is provided.
The control unit
The SOC estimation unit (50) that estimates the SOC of each of the above secondary batteries, and
A discharge indicator (51) that discharges the electric charge stored in the plurality of secondary batteries to the load (6) by turning on the plurality of the relays.
Based on the SOC estimated by the SOC estimation unit, among the plurality of secondary batteries discharged to the load, the relays of some of the secondary batteries are turned off, so that the plurality of secondary batteries are discharged. It is provided with an equalization processing unit (52) for equalizing the SOC of the next battery.
The control unit is an individual when the power prediction unit (53) that predicts the amount of power (W) consumed by the load and the power prediction unit (53) have completed the supply of the power amount to the load while equalizing the SOC. Further, the SOC prediction unit (54) for calculating the predicted SOC which is the predicted value of the SOC of the secondary battery is further provided, and the equalization processing unit uses the estimated value of the SOC by the SOC estimation unit as the predicted SOC. A power supply system (1) configured to turn off the relay in order from the reached secondary battery . The load is a compressor of the freezer (61), a temperature sensor (7 _T ) is provided in the freezer, and the power prediction unit predicts the electric energy based on the measured value of the temperature of the freezer. The power supply system according to claim 1 , which is configured. The control unit is a storage unit (55) that stores OCV-SOC characteristics, which is the relationship between the OCV of the secondary battery and the SOC, and the above-mentioned load to the load without turning off any of the plurality of relays. The non-blocking SOC prediction unit (56) that predicts the SOC of each of the secondary batteries as a non-blocking SOC when the supply of the amount of power is completed, and the above-mentioned in the non-blocking SOC of each of the secondary batteries. The gradient of OCV-SOC characteristics (ΔOCV / ΔSOC) is calculated, and if the gradient of all the secondary batteries is smaller than the predetermined threshold ( _ΔTH ), the secondary battery by the equalization processing unit is used. The power supply system according to claim 1 or 2 , further comprising an off stop command unit (57) for stopping the off process of the relay. The control unit measures the current of each of the secondary batteries other than the reaching secondary battery when the relay of the reaching secondary battery (2 _Z ), which is the secondary battery that has reached the predicted SOC, is turned off. If there is a predicted current prediction unit (58) and the secondary battery in which the predicted current exceeds a predetermined threshold ( _ITH ), the equalization processing unit performs the above-mentioned reaching secondary battery. The power supply system according to claim 1 or 2 , further comprising an off stop command unit for stopping the off process of the relay. The control unit predicts the voltage of each of the secondary batteries other than the reaching secondary battery when the relay of the reaching secondary battery, which is the secondary battery that has reached the predicted SOC, is turned off. If there is a unit (59) and the secondary battery whose predicted voltage is lower than a predetermined threshold (V _TH ), the equalization processing unit performs the relay off processing of the reaching secondary battery. The power supply system according to claim 1 or 2 , further comprising an off-stop command unit for stopping.

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