JP2019187065A - Power supply system - Google Patents

Abstract

To provide a power supply system capable of equalizing an SOC of a plurality of secondary batteries and simplifying a circuit configuration.SOLUTION: A battery module 4 in which a plurality of secondary batteries 2 are connected in parallel to each other, and a control section 5 that controls charging and discharging of the battery module 4 are provided. The control section 5 includes an SOC estimation section 50, a discharge instruction section 51, and an equalization processing section 52. The SOC estimation section 50 estimates the SOC of each secondary battery 2. The discharge instructing section 51 turns on a plurality of relays 3 and discharges a charge stored in the secondary battery 2 to a load 6. The equalization processing section 52 turns off one part of the relays 3 of the secondary batteries 2 among the plurality of the secondary batteries 2 that are discharged, based on the SOC estimated by the SOC estimation section 50. Thereby, the SOC of the plurality of secondary batteries 2 are equalized.SELECTED DRAWING: Figure 1

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 that controls 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 that controls charging / discharging of the battery module is known. In this power supply system, each secondary battery is provided with a relay (see FIG. 21). The control unit controls the on / off operation of these relays. Thereby, it is comprised so that charging / discharging of a secondary battery may be controlled.

  It is known that when a battery module is discharged, variation in SOC (State Of Charge) occurs due to variation in internal resistance of each secondary battery. That is, since the secondary battery having a small internal resistance is likely to be discharged, the SOC is likely to be lowered. Moreover, since a secondary battery with a large internal resistance is difficult to discharge, the SOC is difficult to decrease. When the SOC varies as described above, when discharging is completed, a large current flows from a secondary battery having a high SOC (ie, a high voltage) to a secondary battery having a low SOC (ie, a low voltage). For this reason, there is a possibility that problems such as melting of the relay may occur.

  In order to solve this problem, it has been studied to provide an 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 an 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 is likely to increase. The equalizing circuit is provided with a resistor so that a large current does not flow from a secondary battery having a high SOC to a secondary battery having a low SOC. Therefore, wasteful power consumption occurs due to the resistance.

  This invention is made | formed in view of this subject, and it aims at providing the power supply system which can equalize SOC of a some secondary battery, and can simplify a circuit structure.

One aspect of the present invention is a battery module (4) in which a plurality of series bodies (10) each 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 and discharging of the battery module;
The control unit
An SOC estimation unit (50) for estimating the SOC of each of the secondary batteries;
A discharge instructing section (51) for discharging the charges stored in the plurality of secondary batteries to the load (6) by turning on the plurality of relays;
Based on the SOC estimated by the SOC estimation unit, the relays of some of the secondary batteries among the plurality of secondary batteries that are discharged to the load are turned off, whereby the plurality of secondary batteries are turned off. The power supply system (1) includes an equalization processing unit (52) for equalizing the SOC of the secondary battery.

The control unit of the power supply system includes the equalization processing unit. The equalization processing unit turns off relays of some secondary batteries among the plurality of discharged secondary batteries based on the estimated SOC. Thereby, the SOC of the secondary battery 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 can be simplified. Moreover, since there is no power consumption by the resistance included in the equalization circuit, the power of the secondary battery can be used effectively.

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.
In addition, the code | symbol in the parenthesis described in the means to solve a claim and a subject shows the correspondence with the specific means as described in embodiment mentioned later, and limits the technical scope of this invention. It is not a thing.

  Moreover, the above “equalization” means to reduce the variation in SOC of a plurality of secondary batteries, and is not limited to the meaning of making the SOCs completely equal.

FIG. 2 is a circuit diagram of a power supply system in the first embodiment. FIG. 3 is an operation explanatory diagram of the power supply system in the first embodiment. The figure following FIG. The figure following FIG. The figure following FIG. 5 is a flowchart of a control unit in the first embodiment. The OCV-SOC characteristic in Embodiment 1. FIG. 3 is a cross-sectional view of a battery cell having approximately 100% SOC in the first embodiment. Sectional drawing of the battery cell in Embodiment 1 whose SOC is substantially 0%. FIG. 3 is a side view of the refrigerator car in the first embodiment. The graph showing the time change of the temperature of the freezer in Embodiment 1. FIG. The circuit diagram of the power supply system in Embodiment 2. FIG. 6 is a flowchart of a control unit in the second embodiment. The OCV-SOC characteristic in Embodiment 2. The circuit diagram of the power supply system in Embodiment 3. FIG. 10 is a flowchart of a control unit in the third embodiment. The flowchart following FIG. The circuit diagram of the power supply system in Embodiment 4. FIG. 10 is a flowchart of a control unit in the fourth embodiment. The flowchart following FIG. Operation | movement explanatory drawing of the power supply system in a comparison form.

(Embodiment 1)
An embodiment according to the power supply system will be described with reference to FIGS. As shown in FIG. 1, the power supply system 1 of this 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 each having a secondary battery 2 and a relay 3 connected in series to the secondary battery 2 in parallel. The control unit 5 controls charging / discharging of the battery module 4.

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

  The equalization processing unit 52 turns off the relays 3 of some of the secondary batteries 2 among the plurality of secondary batteries 2 discharged to the load 6 based on the SOC estimated by the SOC estimation unit 50 ( 3 to 5). Thereby, the SOCs of the plurality of secondary batteries 2 are equalized.

As shown in FIG. 1, the secondary battery 2 includes a plurality of battery cells 20. The secondary battery 2 is provided with a voltage sensor 7 _V and a current sensor 7 _I. In addition, a load 6 and a 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. The controller 5 turns on the discharge switch 12 and each relay 3 when discharging the battery module 4. 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 according to the present embodiment is used in a refrigerator car 14. The freezer 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 in the freezer 61.

  The refrigerated vehicle 14 operates a mechanical compressor by the engine during traveling to lower the internal temperature. Further, the engine is stopped when the cargo is carried in and out, and the electric compressor is operated by the battery module 4.

  As shown in FIG. 11, the mechanical compressor is operated during traveling, so that it is maintained at a low temperature. If you open the door when loading / unloading luggage, the temperature rises due to outside air. After that, when the door is closed and the baggage is carried in and out of the store, the electric compressor is operated and the temperature is lowered.

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 necessary for lowering 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 power prediction unit 53 predicts the amount of power W consumed by the compressor (load 6) using the measured value of the temperature of the freezer 61. In addition, the SOC prediction unit 54 calculates a predicted SOC that is a 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 controller 5 turns on the plurality of relays 3 as shown in FIG. Since the internal resistance of the secondary battery 2 varies, as shown in FIG. 3, the SOC of the secondary battery _2a having the smallest internal resistance decreases quickly. When the SOC of the secondary battery 2 _a reaches the predicted SOC, the equalization processing unit 52 turns off the relay 3 _a of the secondary battery 2 _a . Continuing discharge in this state, as shown in FIG. 4, SOC small rechargeable battery 2 _b in the second internal resistance reaches prediction SOC. At this time, the equalization processing unit 52 turns off the relay 3 _b of the secondary battery 2 _b . If the discharge is further 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 3 _c of the secondary battery 2 _c . Thereby, SOC of all the secondary batteries _{2a- 2c} is 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 (a positive electrode 23 _P and a negative electrode 23 _N ), a separator 24 interposed therebetween, and an electrolytic solution 25. The electrode 23 includes a collecting electrode 21 and an active material 22 from which lithium ions are inserted and removed. As shown in FIG. 8, when discharged, lithium ions are desorbed from the negative electrode active material 22 _N, to move the electrolytic solution 25, it is inserted in the positive electrode active material 22 _P.

Further, as shown in FIG. 9, when charged, lithium ions are desorbed from the positive electrode active material 22 _P, by moving the electrolyte solution 25, it is inserted into the anode active material 22 _N.

FIG. 7 shows the OCV-SOC characteristics of the secondary battery 2. The OCV-SOC characteristic is stored in the storage unit 55 (see FIG. 1) as described above. 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 / discharged for a while, the voltage of the secondary battery 2 becomes stable and the OCV can be measured. In this state, the 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 characteristic.

Further, when the secondary battery 2 is discharged, the SOC of the secondary battery 2 decreases. 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 SOC _ini before the discharge is calculated using the measured value. Then, from the current I of the secondary battery 2 being discharged, the discharge time t, and the capacity C of the secondary battery 2, the SOC during discharge can be calculated using the following equation.
SOC = SOC _ini −ΔSOC
= 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. As shown in FIG. 6, the controller 5 first performs step S1. Here, the amount of electric power W consumed by the load 6 (that is, the compressor) is predicted. Thereafter, the process proceeds to step S2, and the current SOC of each secondary battery 2 is estimated.

Next, the process proceeds to step S3, where 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 making the SOC uniform) is calculated. The predicted SOC can be calculated using, for example, the following equation.
Predicted SOC = SOC _ini −ΔW / W _FULL
ΔW = W / N
In the above equation, SOC _ini is the SOC of the secondary battery 2 before discharging, ΔW is the amount of electric power discharged by each secondary battery 2, and W _FULL is the energy of the secondary battery 2 when fully charged. 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. Thereafter, the process proceeds to step S5. Here, it is determined whether or not there is a secondary battery 2 that has reached the predicted SOC. If the determination is Yes, the process proceeds to step S6, and the relay 3 of the secondary battery 2 that has reached the predicted SOC is turned off.

  Thereafter, the process proceeds to step S7. Here, it is determined whether all the relays 3 are turned off. If NO is determined here, the process returns to step S5. Moreover, when it determines with Yes, it complete | finishes.

The effect of this form is demonstrated. As shown in FIG. 1, the control unit 5 of this embodiment includes an equalization processing unit 52. As shown in FIGS. 2 to 5, the equalization processing unit 52 turns off the relays 3 of some of the secondary batteries 2 among the plurality of discharged secondary batteries 2 based on the estimated SOC. . Thereby, 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 life reduction of the relay 3.

That is, as shown in FIGS. 21A and 21B, if the SOC is not equalized, the SOC of the secondary battery _2a having a small internal resistance is quickly reduced. Therefore, after the discharge is stopped, as shown in FIG. 21C, the secondary battery 2 _b , 2 _c (that is, the secondary battery 2 having a high voltage) having a high SOC is changed to the secondary battery 2 _a (having a low SOC. That is, a large current flows to the secondary battery 2) having a low voltage. Therefore, there is a possibility that a malfunction such as melting of the relay 3 occurs. Conventionally, in order to solve this problem, a dedicated circuit (equalization circuit) for equalizing the SOC has been provided. However, in this case, the circuit configuration of the power supply system 1 becomes complicated, and Manufacturing costs tend to be high. On the other hand, in the present embodiment, among the plurality of secondary batteries 2 that are being discharged, the relays 3 of some of the secondary batteries 2 are turned off and the discharge of the other secondary batteries 2 is continued, so that the SOC Are 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.

As shown in FIG. 1, the control unit 5 of the present embodiment further includes a power prediction unit 53 that predicts the amount of power 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 value has reached the predicted SOC (steps S <b> 5 and S <b> 6).
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 an 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 power prediction unit 53 is configured to predict the power amount W based on the measured value of the temperature of the freezer 61.
In this way, it is possible to predict the power consumption W with high accuracy. Therefore, the predicted SOC of each secondary battery 2 can be accurately calculated, and the SOC can be equalized with high accuracy. In addition, the number of operations of the relay 3 can be minimized, and the life reduction of the relay 3 can be suppressed.

  As described above, according to this embodiment, it is possible to provide a power supply system that can equalize the SOCs of a plurality of secondary batteries and can simplify 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 the OCV-SOC characteristics as in the first embodiment. The non-blocking SOC prediction unit 56 predicts the SOC of each secondary battery 2 as the non-blocking 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. Then, all of the secondary battery 2 slope if a predetermined threshold delta _TH smaller, due to the equalization processing section 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 variation region A) in which the OCV hardly changes even when 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 exist in the low fluctuation region A when the relay 3 is not turned off, no large voltage is 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 relay 3 of the secondary battery 2 that is being discharged is turned off to stop the process of equalizing the SOC.

  Next, the flowchart of the control part 5 in this form is demonstrated. As shown in FIG. 13, the control unit 5 first performs steps S <b> 1 to S <b> 4 as in the first embodiment. In this embodiment, after step S4, the process proceeds to step S11. Here, the non-blocking SOC is calculated. Thereafter, the process proceeds to step S12. In step S12, the slope ΔOCV / ΔSOC in the non-blocking SOC of each secondary battery 2 is calculated.

Next, the process proceeds to step S13. Here, it is determined whether or not tilt is present secondary battery 2 exceeds the threshold delta _TH. Here, if it is determined Yes (that is, there is a secondary battery 2 having a large inclination), the process proceeds to step S5 of the first embodiment. On the other hand, if it is determined No (that is, there is no secondary battery 2 having a large inclination), the process proceeds to step S14. Here, it is determined whether or not the scheduled power amount W has been supplied to the load 6. If it is determined Yes, all relays 3 are turned off.

Next, the effect of this form is demonstrated. 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. Then, all of the secondary battery 2 slope if a predetermined threshold delta _TH smaller, due to the equalization processing section 52, stops the off processing of the relay 3.
If it does in this way, it will become less to operate the load 6 only with some secondary batteries 2, and it can suppress that a large current flows into the secondary battery 2. FIG. Therefore, rapid deterioration of the secondary battery 2 can be prevented.
In addition, the same configuration and operational effects as those of the first embodiment are provided.

(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 the above, the control unit 5 includes an off stop command unit 57 and a current prediction unit 58. The current predicting unit 58 determines the current I of each secondary battery 2 other than the reached secondary battery 2 _Z when the relay 3 of the reached secondary battery 2 _Z that is the secondary battery 2 that has reached the predicted SOC is turned off. Predict. When there is a secondary battery 2 in which the predicted current I exceeds a predetermined threshold value I _TH , the off stop command unit 57 turns off the relay 3 of the reached secondary battery 2 _Z by the equalization processing unit 52. Cancel processing.

When the relay 3 of the reaching secondary battery 2 _Z is turned off, the number of 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 I 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 I _TH flows, Since there is a possibility that the service life may be reduced or the relay 3 may be melted, the relay 3 of the reaching secondary battery 2 _Z is not turned off.

Next, the flowchart of the control part 5 is demonstrated using FIG. 16, FIG. As shown in FIG. 16, the control unit 5 of the present embodiment first performs steps S <b> 1 to S <b> 5 as in the first embodiment. And step S21 is performed after step S5. 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.

Thereafter, 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 another 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 scheduled amount of power W has been supplied to the load 6. If YES is determined here, the process proceeds to step S24, and all the relays 3 are turned off.

When it is determined No in step S22 (i.e., if even off the relay 3 reaching the secondary battery 2 _Z, is judged not a large current flows other secondary batteries 2), in step S25 Move. Then, the relay 3 of the reaching secondary battery 2 _Z is turned off. Thereafter, the process proceeds to step S26, and it is determined whether or not all the relays 3 are turned off. If it is determined Yes, the process ends. If it is determined No, the process returns to Step S5.

The effect of this form is demonstrated. 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 batteries 2, so that it is possible to suppress problems such as a decrease in the life of the secondary battery 2.
In addition, the same configuration and operational effects as those of the first embodiment are provided.

(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 the above, the control unit 5 includes an off stop command unit 57 and a voltage prediction unit 59. The voltage predicting unit 59 is the voltage of each secondary battery 2 other than the reached secondary battery 2 _Z when the relay 3 of the secondary battery 2 that has reached the predicted SOC (that is, the reached secondary battery 2 _Z ) is turned off. Predict V. When there is a secondary battery 2 in which the predicted voltage is lower than a predetermined threshold value V _TH , the off cancellation command unit 57 performs an off process of the relay 3 of the reached secondary battery 2 _Z by the equalization processing unit 52. Cancel.

When the relay 3 of the reaching secondary battery 2 _Z is turned off, as described above, the number of 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 of the secondary battery 2 (that is, CCV: Closed Circuit Voltage) can be expressed by the following formula, 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 part 5 is demonstrated using FIG. 19, FIG. As shown in FIG. 19, the control unit 5 of the present embodiment first performs steps S <b> 1 to S <b> 5 as in the first embodiment. And after performing step S5, step S31 is performed. Here, the voltage V of the remaining secondary batteries 2 after the relay 3 of the reaching secondary battery 2 _Z is turned off is predicted.

Thereafter, the process proceeds to step S32. Here, it is determined whether or not there is a secondary battery 2 in which the predicted voltage V is lower than the threshold value V _TH . Here, when 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 greatly decreases), the process proceeds to step S33. In step S <b> 33, it is determined whether or not the scheduled power amount W is supplied to the load 6. If YES is determined here, the process proceeds to step S34 and all relays 3 are turned off.

On the other hand, if it is determined No in step S32 (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 is not greatly reduced), the process proceeds to step S35. Then, the relay 3 of the reaching secondary battery 2 _Z is turned off. Then, it moves to step S36 and it is judged whether all the relays 3 were turned off. If it is determined Yes, the process ends. If it is determined No, the process returns to Step S5.

The effect of this form is demonstrated. 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 is greatly reduced, and a problem that the secondary battery 2 is likely to deteriorate can be suppressed.
In addition, the same configuration and operational effects as those of the first embodiment are provided.

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

DESCRIPTION OF SYMBOLS 1 Power supply system 10 Serial body 2 Secondary battery 3 Relay 4 Battery module 5 Control part 50 SOC estimation part 51 Discharge instruction | indication part 52 Equalization process part

Claims (6)

A battery module (4) formed by connecting a plurality of serial bodies (10) each having a secondary battery (2) and a relay (3) connected in series to the secondary battery in parallel;
A control unit (5) for controlling charging and discharging of the battery module;
The control unit
An SOC estimation unit (50) for estimating the SOC of each of the secondary batteries;
A discharge instructing section (51) for discharging the charges stored in the plurality of secondary batteries to the load (6) by turning on the plurality of relays;
Based on the SOC estimated by the SOC estimation unit, the relays of some of the secondary batteries among the plurality of secondary batteries that are discharged to the load are turned off, whereby the plurality of secondary batteries are turned off. A power supply system (1) provided with the equalization process part (52) which equalizes said SOC of a secondary battery.   The control unit predicts the amount of power (W) consumed by the load, and the power prediction unit (53), and when the supply of the amount of power to the load is completed while equalizing the SOC, An SOC prediction unit (54) that calculates a predicted SOC that is a predicted value of the SOC of the secondary battery, and the equalization processing unit converts the estimated value of the SOC by the SOC estimation unit into the predicted SOC. The power supply system according to claim 1, wherein the power supply system is configured to turn off the relay in order from the arrived 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 amount of power based on a measured value of the temperature of the freezer. The power supply system according to claim 2, which is configured. The control unit stores the OCV-SOC characteristic that is a relationship between the OCV of the secondary battery and the SOC, and the load to the load without turning off any of the plurality of relays. A 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 electric power is completed, and the above-mentioned in the non-blocking SOC of each of the secondary batteries When the slope of the OCV-SOC characteristic (ΔOCV / ΔSOC) is calculated and the slopes of all the secondary batteries are smaller than a predetermined threshold value (Δ _TH ), the secondary battery by the equalization processing unit The power supply system according to claim 2 or 3, further comprising an off stop command section (57) for canceling off processing of the relay. The controller controls the currents of the individual secondary batteries other than the reached secondary battery when the relay of the reached secondary battery (2 _Z ) that is the secondary battery that has reached the predicted SOC is turned off. When there is a current prediction unit (58) to predict and the secondary battery in which the predicted current exceeds a predetermined threshold (I _TH ), the equalization processing unit performs the above of the reaching secondary battery The power supply system according to claim 2, further comprising an off stop command unit that stops the relay off process. The control unit predicts a voltage of each of the secondary batteries other than the reaching secondary battery when the relay of the reaching secondary battery that is the secondary battery that has reached the predicted SOC is turned off. Part (59) and the secondary battery having a predicted voltage lower than a predetermined threshold value (V _TH ), the relay process of the reaching secondary battery is turned off by the equalization processing part. The power supply system according to claim 2, further comprising an off stop command unit to stop.

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