JP2014187807A - Power storage system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a fuse from getting melted although there is no need to melt a fuse in a plurality of parallel-connected fuses.SOLUTION: A power storage system has: a power storage device (10) including a plurality of power storage elements (12) connected in parallel, a plurality of fuses (12b) connected in parallel with each of the plurality of power storage elements, and a controller (40) for controlling the charge/discharge of the power storage device. The controller uses the voltage values of the plurality of power storage elements and the internal resistance of each power storage element to calculate a current value flowing in each power storage element. When the amount of damage to each fuse corresponding to the calculated current value is larger than a threshold, the controller limits the charge and/or the discharge of the power storage device.

Description

  The present invention relates to a technique for grasping the amount of damage of a fuse and suppressing the fuse from operating under conditions other than the conditions under which the fuse should operate.

  In the assembled battery described in Patent Document 1, in a configuration in which a plurality of batteries are connected in parallel, a fuse is connected to each of the single cells connected in parallel. The fuse cuts off the current path by fusing when an excessive current flows.

JP 05-275116 A

  In the configuration described in Patent Document 1, it is necessary to consider the deterioration of the fuse. When the deterioration of the fuse progresses, the fuse may be blown even though it is not necessary to blow the fuse. If the fuse is blown carelessly, a current easily flows through another fuse connected in parallel, and the deterioration of the other fuse is promoted.

  The power storage system of the present invention includes a power storage device and a controller that controls charging / discharging of the power storage device. The power storage device includes a plurality of power storage elements connected in parallel, and a fuse is connected in series to each power storage element. Here, the plurality of fuses connected to the plurality of power storage elements are connected in parallel.

  The controller calculates the value of the current flowing through each power storage element using the voltage values of the plurality of power storage elements and the internal resistance of each power storage element. Since the plurality of power storage elements are connected in parallel, the voltage values of the plurality of power storage elements are aligned. Thereby, a specific voltage value (one voltage value) is obtained as the voltage values of the plurality of power storage elements. On the other hand, in a plurality of power storage elements connected in parallel, variations may occur in the deterioration state (internal resistance), and the current values flowing in the power storage elements differ from each other according to the variation in the deterioration state.

  The controller limits at least one of charging and discharging (referred to as charging / discharging) of the power storage device when the damage amount of each fuse corresponding to the calculated current value is larger than a threshold value. The deterioration of the fuse depends on the value of the current flowing through the fuse. Specifically, as the current value flowing through the fuse increases, the deterioration of the fuse easily proceeds. For this reason, the amount of damage of each fuse can be calculated by calculating the value of the current flowing through each power storage element (in other words, each fuse).

  By limiting charging / discharging of the power storage device when the amount of damage to the fuse is larger than the threshold value, it is possible to suppress the progress of deterioration of the fuse. That is, if charging / discharging is limited, it is difficult for current to flow through the fuse, and the deterioration of the fuse can be suppressed. When the deterioration of the fuse progresses, the fuse may be blown even though it is not necessary to blow the fuse. Therefore, as described above, by restricting charging / discharging of the power storage device, it is possible to suppress the fuse from being easily blown.

  When charging / discharging of the power storage device is controlled, an upper limit value of allowable power is set for each of charging and discharging. Specifically, charging / discharging of the power storage device is controlled so that charging power or discharging power does not exceed an upper limit value. Here, when charging is limited, the upper limit value related to charging is reduced. Moreover, when limiting discharge, the upper limit regarding discharge is reduced.

  As described above, the larger the current value flowing through the fuse, the easier the deterioration of the fuse proceeds. Therefore, the greater the current value, the greater the amount of damage. By calculating the amount of damage corresponding to the current value flowing through each power storage element (each fuse) and accumulating the amount of damage, the current amount of damage in the fuse can be grasped. Based on the current damage amount, charging / discharging of the power storage device can be controlled.

  When limiting the charging / discharging of the power storage device, a limiting amount corresponding to the difference between the damage amount and the threshold value can be set. As described above, when the upper limit value related to charging / discharging is lowered, the upper limit value can be lowered by the limit amount. Thereby, when limiting charging / discharging, it is possible to perform appropriate limitation while reflecting the difference between the damage amount and the threshold value. Specifically, it is possible to suppress the charge / discharge from being restricted excessively, or to suppress the charge / discharge restriction from being insufficient.

  When the current values flowing through the plurality of fuses are different from each other, the damage amounts of the plurality of fuses are also different from each other. In this case, charging / discharging of the power storage device can be controlled based on the largest damage amount. Specifically, charging / discharging can be limited when the largest amount of damage is greater than a threshold value. The fuse with the greatest amount of damage is most degraded. For this reason, it is preferable to prevent the fuse that is most deteriorated from being inadvertently blown out.

  The power storage device can be configured by a plurality of power storage blocks. Here, the plurality of power storage blocks can be connected in series, and each power storage block can be constituted by a plurality of power storage elements connected in parallel. In such a configuration, the damage amount of each fuse is calculated based on the value of the current flowing through each power storage element in each power storage block. Based on the amount of damage in these fuses, charging / discharging of the power storage device is controlled.

  By using the current sensor, the value of the current flowing through the power storage device can be detected. Here, since the plurality of power storage elements are connected in parallel, the sum of the current values flowing through the plurality of power storage elements becomes the current value detected by the current sensor. When calculating (estimating) the current value flowing through each power storage element using the voltage value and internal resistance of the power storage element, the estimated current value is in accordance with the actual measurement value by comparing the sum of the current values and the detected current value. It can be confirmed whether or not. When the sum of the current values and the detected current value match, the current value calculated (estimated) at this time can be used as the current value flowing through each power storage element.

  By using the voltage sensor, it is possible to detect voltage values in a plurality of power storage elements connected in parallel. If the voltage value is detected in this manner, the value of the current flowing through each power storage element can be calculated (estimated) by specifying the internal resistance of each power storage element.

It is a figure which shows the structure of a battery system. It is a figure which shows the structure of an assembled battery and a monitoring unit. It is a figure which shows the structure of a cell. It is a figure which shows the structure which adjusts the temperature of an assembled battery. It is a figure which shows the characteristic of a fuse. It is a flowchart which shows the process which estimates the electric current value which flows into a cell. It is a figure explaining the method of estimating the environmental temperature of a cell. It is a figure which shows the relationship between the thermal resistance at the time of the thermal radiation of a cell, and the output of a fan. It is a flowchart which shows the process which estimates the electric current value which flows into a cell. It is a flowchart which shows the process which controls the output of an assembled battery based on the amount of damage of a fuse. It is a figure which shows the amount of damage of a fuse, and the change of output electric power. It is a flowchart which shows the process which controls the input of an assembled battery based on the amount of damage of a fuse. It is a figure which shows the amount of damage of a fuse, and the change of input electric power.

  Examples of the present invention will be described below.

  A battery system (corresponding to the power storage system of the present invention) that is Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a battery system. The battery system of this embodiment is mounted on a vehicle.

  Vehicles include hybrid cars and electric cars. The hybrid vehicle includes an engine or a fuel cell as a power source for running the vehicle in addition to the assembled battery described later. The electric vehicle includes only an assembled battery described later as a power source for running the vehicle.

  A system main relay SMR-B is provided on the positive electrode line PL connected to the positive electrode terminal of the assembled battery (corresponding to the power storage device of the present invention) 10. System main relay SMR-B is switched between ON and OFF by receiving a control signal from controller 40. A system main relay SMR-G is provided on the negative electrode line NL connected to the negative electrode terminal of the assembled battery 10. System main relay SMR-G is switched between on and off by receiving a control signal from controller 40.

  A system main relay SMR-P and a current limiting resistor R are connected in parallel to the system main relay SMR-G. System main relay SMR-P and current limiting resistor R are connected in series. System main relay SMR-P is switched between on and off by receiving a control signal from controller 40. The current limiting resistor R is used for suppressing an inrush current from flowing when the assembled battery 10 is connected to a load (specifically, a booster circuit 32 described later).

  When connecting the assembled battery 10 to a load, the controller 40 switches the system main relays SMR-B and SMR-P from off to on. Thereby, a current can be passed through the current limiting resistor R, and the inrush current can be suppressed from flowing. Here, when the ignition switch of the vehicle is switched from OFF to ON, the assembled battery 10 is connected to the load. Information relating to turning on and off the ignition switch is input to the controller 40.

  Next, the controller 40 switches the system main relay SMR-G from off to on and switches the system main relay SMR-P from on to off. Thereby, connection of the assembled battery 10 and load is completed, and the battery system shown in FIG. 1 will be in a starting state (Ready-On). On the other hand, when cutting off the connection between the assembled battery 10 and the load, the controller 40 switches the system main relays SMR-B and SMR-G from on to off. Thereby, the battery system shown in FIG. 1 is in a stopped state (Ready-Off). Here, when the ignition switch is switched from on to off, the connection between the assembled battery 10 and the load is cut off.

  The current sensor 31 detects the current value Ib flowing through the assembled battery 10 and outputs the detection result to the controller 40. In the present embodiment, when the assembled battery 10 is being discharged, the current value detected by the current sensor 31 is set to a positive value. Further, when the battery pack 10 is being charged, the current value detected by the current sensor 31 is a negative value.

  In the present embodiment, the current sensor 31 is provided on the positive electrode line PL, but is not limited thereto. That is, the current sensor 31 only needs to detect the current value Ib flowing through the assembled battery 10. Specifically, the current sensor 31 can be provided in the negative electrode line NL. A plurality of current sensors 31 can also be used. In consideration of cost, physique, and the like, it is preferable to provide one current sensor 31 for one assembled battery 10 as in the present embodiment.

  The booster circuit 32 boosts the output voltage of the assembled battery 10 and outputs the boosted power to the inverter 33. Further, the booster circuit 32 can step down the output voltage of the inverter 33 and output the lowered power to the assembled battery 10. The booster circuit 32 operates in response to a control signal from the controller 40. In the battery system of this embodiment, the booster circuit 32 is used, but the booster circuit 32 may be omitted.

  The inverter 33 converts the DC power output from the booster circuit 32 into AC power, and outputs the AC power to the motor / generator 34. The inverter 33 converts AC power generated by the motor / generator 34 into DC power and outputs the DC power to the booster circuit 32. As the motor generator 34, for example, a three-phase AC motor can be used.

  Motor generator 34 receives AC power from inverter 33 and generates kinetic energy for running the vehicle. When the vehicle is driven using the output power of the assembled battery 10, the kinetic energy generated by the motor / generator 34 is transmitted to the wheels.

  When the vehicle is decelerated or stopped, the motor generator 34 converts kinetic energy generated during braking of the vehicle into electrical energy (AC power). The inverter 33 converts AC power generated by the motor / generator 34 into DC power and outputs the DC power to the booster circuit 32. The booster circuit 32 outputs the electric power from the inverter 33 to the assembled battery 10. Thereby, regenerative electric power can be stored in the assembled battery 10.

  The controller 40 includes a memory 41, and various types of information for the controller 40 to perform predetermined processing are stored in the memory 41. In the present embodiment, the memory 41 is built in the controller 40, but the memory 41 may be provided outside the controller 40.

As will be described later, the monitoring unit 20 detects the voltage value V _j of the battery block included in the assembled battery 10 and outputs the detection result to the controller 40. In FIG. 2, the structure of the assembled battery 10 and the monitoring unit 20 is shown. As shown in FIG. 2, the assembled battery 10 includes a plurality of battery blocks (corresponding to the storage block of the present invention) 11 connected in series. By connecting a plurality of battery blocks 11 in series, the output voltage of the assembled battery 10 can be secured. Here, the number of battery blocks 11 can be appropriately set in consideration of the voltage required for the assembled battery 10.

  Each battery block 11 has a plurality of single cells (corresponding to the storage element of the present invention) 12 connected in parallel. By connecting the plurality of single cells 12 in parallel, the full charge capacity of the battery block 11 (the assembled battery 10) can be increased. For example, when the vehicle is driven using the output of the assembled battery 10, the traveling distance can be extended by increasing the full charge capacity of the assembled battery 10. The number of single cells 12 constituting each battery block 11 can be appropriately set in consideration of the full charge capacity required for the assembled battery 10.

A monitoring IC (Integrated Circuit) 21 is connected to each battery block 11 in parallel. The monitoring unit 20 has a plurality of monitoring ICs 21, and as many monitoring ICs 21 as the number of battery blocks 11 are provided. Each monitoring IC 21 detects the voltage value V _j of each battery block 11 and outputs the detection result to the controller 40.

  As the unit cell 12, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor can be used instead of the secondary battery. For example, as the single battery 12, a 18650 type battery can be used. The 18650 type battery is a so-called cylindrical battery, which has a diameter of 18 [mm] and a length of 65.0 [mm].

  In a cylindrical battery, a battery case is formed in a cylindrical shape, and a power generation element for charging and discharging is accommodated in the battery case. The configuration of the power generation element will be described later. The shape of the unit cell 12 can be set as appropriate. For example, a square battery can be used as the single battery 12. In the rectangular battery, a battery case is formed in a shape along a rectangular parallelepiped.

  As shown in FIG. 3, the unit cell 12 includes a power generation element 12 a and a fuse 12 b. The power generation element 12 a and the fuse 12 b are accommodated in a battery case that constitutes the exterior of the unit cell 12. The power generation element 12a is an element that performs charging and discharging, and includes a positive electrode plate, a negative electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a current collector plate and a positive electrode active material layer formed on the surface of the current collector plate. The negative electrode plate has a current collector plate and a negative electrode active material layer formed on the surface of the current collector plate. The positive electrode active material layer includes a positive electrode active material and a conductive agent, and the negative electrode active material layer includes a negative electrode active material and a conductive agent.

When a lithium ion secondary battery is used as the single battery 12, for example, the current collector plate of the positive electrode plate can be made of aluminum, and the current collector plate of the negative electrode plate can be made of copper. As the positive electrode active material, for example, LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ can be used, and as the negative electrode active material, for example, carbon can be used. An electrolyte solution is infiltrated into the separator, the positive electrode active material layer, and the negative electrode active material layer. Instead of using the electrolytic solution, a solid electrolyte layer can be disposed between the positive electrode plate and the negative electrode plate.

  The fuse 12b is used to interrupt the current path of the unit cell 12. Specifically, when the value of the current flowing through the fuse 12b becomes larger than a preset value, the fuse 12b is blown. By blowing the fuse 12b, the current path of the unit cell 12 can be mechanically interrupted. Thereby, it can prevent that an excessive electric current flows into the electric power generation element 12a, and can protect the cell 12 (electric power generation element 12a).

  In this embodiment, the fuse 12b is accommodated in the battery case, but the fuse 12b can be provided outside the battery case. When the fuse 12 b is provided outside the battery case, the fuse 12 b is connected to each unit cell 12, and the fuse 12 b is connected in series with the unit cell 12.

  Next, a structure for adjusting the temperature of the assembled battery 10 (unit cell 12) will be described with reference to FIG. The arrow shown in FIG. 4 has shown the main moving direction of the air used for the temperature control of the cell 12. In the structure shown in FIG. 4, a cylindrical battery is used as the single battery 12, and the single battery 12 extends in a direction perpendicular to the paper surface of FIG. 4. The unit cell 12 shown in FIG. 4 is a cross-sectional view when the unit cell 12 is cut along a plane orthogonal to the longitudinal direction of the unit cell 12.

  As shown in FIG. 4, the plurality of battery blocks 11 are accommodated in the case 13. A partition plate 14 is provided inside the case 13, and each battery block 11 is accommodated in a space partitioned by the partition plate 14. Here, the plurality of battery blocks 11 are arranged side by side in a predetermined direction (left-right direction in FIG. 4). Further, the plurality of single cells 12 constituting each battery block 11 are arranged side by side in two directions (vertical direction and horizontal direction in FIG. 4).

  An intake duct 15 and an exhaust duct 16 are connected to the case 13. The intake duct 15 and the exhaust duct 16 are provided at positions sandwiching the case 13. The intake duct 15 extends in the arrangement direction of the plurality of battery blocks 11, and a fan 50 is connected to the intake duct 15. The driving of the fan 50 is controlled by the controller 40.

By driving the fan 50, air can be taken into the intake duct 15. For example, by exposing an opening formed at one end of the intake duct 15 into the vehicle interior, air in the vehicle interior can be taken into the intake duct 15. The passenger compartment is a space where passengers get on. A temperature sensor 51 is provided in the intake duct 15. The temperature sensor 51 detects the temperature T _{input of} air moving through the intake duct 15, in other words, the temperature T _input of air supplied to the unit cell 12, and outputs the detection result to the controller 40.

  The case 13 has a plurality of air inlets 13 a at the connection portion with the air intake duct 15. The air moving inside the intake duct 15 passes through the intake port 13 a and enters the inside of the case 13. Thereby, air contacts the cell 12 of each battery block 11, and heat exchange is performed between the air and the cell 12.

  For example, when the cell 12 is generating heat due to charging / discharging or the like, the temperature rise of the cell 12 can be suppressed by bringing cooling air into contact with the cell 12. In addition, when the unit cell 12 is excessively cooled due to an external environment or the like, the temperature drop of the unit cell 12 can be suppressed by bringing heating air into contact with the unit cell 12. The air in the passenger compartment is easily set to a temperature suitable for adjusting the temperature of the unit cell 12 by an air conditioner installed in the vehicle. For this reason, it becomes easy to adjust the temperature of the unit cell 12 by guiding the air in the vehicle compartment to the unit cell 12.

The case 13 has a plurality of exhaust ports 13 b at the connection portion with the exhaust duct 16. The air after heat exchange with the unit cell 12 passes through the exhaust port 13 b and is guided to the exhaust duct 16. The air guided to the exhaust duct 16 moves along the exhaust duct 16 and is discharged to a predetermined place. A temperature sensor 52 is provided in the exhaust duct 16. The temperature sensor 52 detects the temperature T _{output of} the air moving through the exhaust duct 16, in other words, the temperature T _output of the air after heat exchange with the unit cell 12, and outputs the detection result to the controller 40.

  In the present embodiment, the temperature of the assembled battery 10 (unit cell 12) is adjusted using the structure shown in FIG. 4, but the present invention is not limited to this. It is sufficient if air can be supplied to the unit cell 12 to adjust the temperature of the unit cell 12, and a known structure can be appropriately adopted as the structure for moving the air. For example, in the present embodiment, the fan 50 is connected to the intake duct 15, but the fan 50 can be connected to the exhaust duct 16.

  In the assembled battery 10 of the present embodiment, a fuse 12 b is provided for each single battery 12. Here, the larger the value of the current flowing through the fuse 12b, the easier the fuse 12b deteriorates, and the more the deterioration of the fuse 12b progresses, the easier the fuse 12b blows. The fact that the fuse 12b is easily blown means that the fuse 12b is blown even though the current value flowing through the fuse 12b is smaller than the current value at which the fuse 12b should be blown.

  When the fuse 12b is blown, no current flows through the unit cell 12 including the blown fuse 12b. Here, since a plurality of single cells 12 (a plurality of fuses 12 b) are connected in parallel in the battery block 11, if at least one fuse 12 b is blown in the battery block 11, the unfused fuse 12 b The current that was supposed to flow through the blown fuse 12b also flows. As a result, the value of the current flowing through the unfused fuse 12b increases.

  When the value of the current flowing through the unit cell 12 including the unfused fuse 12b increases, in other words, when the current load on the unit cell 12 increases, the salt concentration tends to be biased inside the unit cell 12. And it becomes easy to generate | occur | produce with the bias | inclination of salt concentration, and the internal resistance of the cell 12 may rise. Further, when a lithium ion secondary battery is used as the single battery 12, lithium may be deposited due to an increase in current load on the single battery 12.

  Furthermore, if the value of the current flowing through the unfused fuse 12b increases, the fuse 12b is likely to deteriorate. As the deterioration of the fuse 12b progresses, the fuse 12b is likely to blow as shown in FIG. FIG. 5 shows the characteristics of the fuse 12b. The horizontal axis represents the current value, and the vertical axis represents the energization time. In the characteristic line set in advance, a time during which energization can be continued at an arbitrary current value (energization time) is defined.

  In the characteristic line shown in FIG. 5, the energization time is shortened as the current value increases. In other words, the energization time is lengthened as the current value decreases. Here, when the energization time at a specific current value becomes longer than the energization time defined by the characteristic line (set value), the fuse 12b is blown. Further, according to the characteristic line (set value), the fuse 12b is easily blown as the current value increases even when the energization time is the same.

  As the deterioration of the fuse 12b proceeds, the characteristic line changes as indicated by the arrows in FIG. In the characteristic line after deterioration, the energization time at a specific current value is shorter than that in the preset characteristic line. Thereby, the fuse 12b is easily blown. As described above, when the fuse 12b is blown in one battery block 11, a current easily flows through the unfused fuse 12b, and the unfused fuse 12b is likely to deteriorate. And there exists a possibility that the fuse 12b in a non-blown state may be blown in a chain.

Thus, in this embodiment, the damage amount of the fuse 12b is calculated, and the input / output of the assembled battery 10 is controlled based on the damage amount so that the fuse 12b is not inadvertently blown. Here, the damage amount of the fuse 12b depends on the current value I _i flowing through the fuse 12b as described above. For this reason, first, it is necessary to specify the current value I _i flowing through each of the plurality of fuses 12 b included in the battery block 11.

If a current sensor is provided for each fuse 12b (each cell 12) included in the battery block 11, the current value I _i flowing through each fuse 12b can be detected. However, in this case, the number of current sensors increases too much, and considering the cost and size, it is not possible to provide a current sensor for each fuse 12b. Therefore, in the configuration of the battery system shown in FIG. 1, in other words, in the configuration in which the current sensor 31 is provided for the assembled battery 10, it is necessary to estimate the current value I _i flowing through each fuse 12b.

The process of estimating the current value I _i flowing through each fuse 12b (each cell 12) will be described with reference to the flowchart shown in FIG. The process shown in FIG. 6 is executed by the controller 40 and is repeatedly performed at a predetermined cycle (dt).

In step S101, the controller 40 detects the intake air temperature T _input and the exhaust gas temperature T _output based on the outputs of the temperature sensors 51 and 52 (see FIG. 4). Further, the controller 40 detects the current value Ib flowing through the assembled battery 10 based on the output of the current sensor 31.

In step S102, the controller 40 sets the voltage value V _j of each battery block 11. This voltage value V _j is not a voltage value detected by the monitoring IC 21 but a voltage value set in calculation. In step S <b> 103, the controller 40 calculates a resistance value (internal resistance) R _i of each unit cell 12 included in each battery block 11. Specifically, the resistance value R _i can be calculated based on the following formula (1).

As shown in the above formula (1), the current resistance value R _i of each unit cell 12 can be calculated by multiplying the initial resistance value R _0i by the deterioration rate r _i . The initial state is a state before the deterioration of the unit cell 12, for example, a state immediately after the unit cell 12 is manufactured. T shown in the above formula (1) indicates time.

The deterioration rate r _i is a deterioration rate related to the resistance value of the unit cell 12 and is specified by a method described later. As the deterioration of the unit cell 12 progresses, the resistance value of the unit cell 12 increases. Therefore, as the unit cell 12 progresses, the deterioration rate r _i becomes larger than “1”. When the unit cell 12 is not deteriorated, the deterioration rate r _i is “1”.

The resistance value of the unit cell 12 depends on the value of the current flowing through the unit cell 12, the SOC (State of Charge) of the unit cell 12, and the temperature of the unit cell 12. For this reason, the resistance value R _0i in the initial state can also be specified from the current value I _{i of} the cell 12, the SOC (SOC _i ) of the cell 12, and the temperature T _{i of the} cell 12. Here, the SOC is the ratio of the current charge capacity to the full charge capacity.

Specifically, if the correspondence relationship between the resistance value R _0i , the current value I _i , the SOC _i, and the temperature T _i is obtained in advance by experiments or the like, the current value I _i , the SOC _i, and the temperature T _i can be specified. The resistance value R _0i can be calculated. Here, the correspondence relationship described above can be expressed as a map or a function, and information regarding the correspondence relationship can be stored in the memory 41. The current value I _i , SOC _i and temperature T _i are specified by the processing described later. Further, the deterioration rate r _i is also specified by the processing described later.

In step S104, the controller 40 calculates an OCV (Open Circuit Voltage) of the unit cell 12. Since the OCV and the SOC have a predetermined correspondence relationship, the OCV can be calculated from the SOC if the correspondence relationship is obtained in advance by an experiment or the like. Specifically, the controller 40 calculates OCV _i corresponding to SOC _i . The correspondence relationship between the OCV and the SOC can be expressed as a map or a function, and information regarding this correspondence relationship can be stored in the memory 41.

In step S <b> 105, the controller 40 calculates a current value I _i flowing through each unit cell 12. The calculation of the current value I _i is performed for each single battery 12 included in each battery block 11. Specifically, the current value I _i can be calculated based on the following formula (2).

In the above equation (2), the value calculated in the process of step S104 is used as OCV _i . Further, as V _j , the value set in the process of step S102 is used. Furthermore, as R _i , the value calculated in the process of step S103 is used. Since the plurality of single cells 12 included in each battery block 11 are connected in parallel, the voltage values in the plurality of single cells 12 are equal to each other and become the voltage value V _j . On the other hand, when the resistance values R _i are different from each other in the plurality of single cells 12 included in each battery block 11, the current values I _i are different from each other.

In step S <b> 106, the controller 40 calculates the integrated value ΣI _i by integrating the current values I _i of all the unit cells 12 included in the battery block 11. Then, the controller 40 determines whether or not the current value Ib detected in the process of step S101 matches the integrated value ΣI _i .

Here, if the integrated value ΣI _i matches the current value Ib, the controller 40 determines that the current value I _i estimated by each unit cell 12 matches the measured value, and the process of step S107 I do. On the other hand, if the integrated value ΣI _i does not match the current value Ib, the controller 40 determines that the current value I _i estimated by each unit cell 12 does not match the actual measurement value, and performs the process of step S102. Return.

The processing from step S102 to step S106 is repeated until the integrated value ΣI _i matches the current value Ib. That is, in the processing from step S102 to step S106, convergence calculation is performed, and an integrated value ΣI _i that matches the current value Ib is specified. In other words, the current value I _i of each unit cell 12 included in the battery block 11 is specified. As the convergence calculation method, for example, a known method such as a bisection method or a Newton method can be used.

In this embodiment, it is determined whether or not the integrated value ΣI _i matches the current value Ib. However, the present invention is not limited to this. Specifically, when the difference between the integrated value ΣI _i and the current value Ib is within the allowable range, the controller 40 can perform the process of step S107. Since the current value Ib is a value detected by the current sensor 31, the current value Ib may include a detection error of the current sensor 31. In consideration of this detection error, the allowable range described above can be set. The allowable range can be set in advance, and information regarding the allowable range can be stored in the memory 41.

In step S107, the controller 40 calculates the environmental temperature T _ia of each unit cell 12. The environmental temperature T _ia is the temperature around the unit cell 12. The environmental temperature T _ia of each unit cell 12 can be specified using the intake air temperature T _input and the exhaust gas temperature T _output, as shown in FIG. In FIG. 7, the horizontal axis indicates the number of the unit cell 12 included in the battery module 11, and the vertical axis indicates the environmental temperature _Tia . In the structure shown in FIG. No. 1 cell 12 is disposed at a position closest to the air inlet 13a. The environmental temperature T _ia of one unit cell 12 can be regarded as being equal to the intake air temperature T _input .

No. No. 2 unit cell 12 is No.2. No. 1 cell 12 is further away from the air inlet 13a. No. 2 cell 12 has an environmental temperature T _ia of No. It becomes higher than the environmental temperature T _ia (intake air temperature T _input ) of one single cell 12. As the number of the unit cell 12 increases, the unit cell 12 moves away from the air inlet 13a. Therefore, as the number of the unit cell 12 increases, the environmental temperature _{Tia of the unit} cell 12 increases. No. km unit cell 12 is arranged at the position closest to the exhaust port 13b. It can be considered that the environmental temperature T _ia of the km unit cell 12 is equal to the exhaust temperature T _output .

As described above, the environmental temperature T _ia of each unit cell 12 is determined based on the intake temperature T _input and the exhaust temperature T _output as shown in FIG. 7 by considering the position where each unit cell 12 is disposed. Can be estimated. The temperature characteristics shown in FIG. 7 can be prepared as a function or a map by conducting an experiment in advance. Based on this function or map and the detected intake air temperature T _input and exhaust gas temperature T _output , the temperature characteristics shown in FIG. 7 can be specified. If the temperature characteristics shown in FIG. 7 are specified, the environmental temperature T _ia of each cell 12 can be estimated.

Moreover, the controller 40 calculates thermal resistance _Ria at the time of heat dissipation of the cell 12 in step S107. The thermal resistance R _ia can be calculated using the relationship shown in FIG. In FIG. 8, the horizontal axis indicates the output of the fan 50, in other words, the air volume supplied from the fan 50. Further, the vertical axis of FIG. 8 indicates the thermal resistance R _ia when the unit cell 12 is radiating heat.

As shown in FIG. 8, the higher the output of the fan 50, in other words, the greater the amount of air supplied from the fan 50, the lower the thermal resistance R _ia of each unit cell 12. Here, as the thermal resistance R _ia decreases, the unit cell 12 is more easily dissipated. The single battery 12 (No. 1 battery 12) closest to the air inlet 13a is likely to receive air from the fan 50. _Therefore , as the output of the fan 50 increases, the thermal resistance _Ria tends to decrease.

On the other hand, in the single battery 12 (No. km battery 12) closest to the exhaust port 13b, it is difficult to receive air from the fan 50. Therefore, even if the output of the fan 50 increases, the thermal resistance _Ria is unlikely to decrease. Thus, the thermal resistance _Ria is less likely to decrease as the position of the unit cell 12 moves away from the air inlet 13a.

If the thermal resistance characteristics shown in FIG. 8 are obtained in advance for each unit cell 12 through experiments or the like, the thermal resistance R _ia of each unit cell 12 can be calculated by specifying the output of the fan 50. The thermal resistance characteristics shown in FIG. 8 can be expressed as a map or a function, and information regarding the thermal resistance characteristics can be stored in the memory 41. When the temperature of the assembled battery 10 (unit cell 12) is adjusted, the controller 40 controls the drive of the fan 50, so the controller 50 can specify the output of the fan 50.

In step S108, the controller 40 calculates the temperature _{T i} of each cell 12, and updates the battery temperature _{T i} stored in the memory 41. That is, each time to calculate the battery temperature T _i, erases the battery temperature T _i stored in the memory 41, and stores the battery temperature T _i which is newly calculated in the memory 41. Battery temperature T _i can be calculated based on the following equation (3).

According to the above equation (3), the current battery temperature T _i (t + dt) takes into account the amount of heat generated and the amount of heat released from the unit cell 12 for a predetermined time dt, based on the previous battery temperature T _i (t). Can be calculated. C shown in the above formula (3) indicates the heat capacity of the unit cell 12. The second term on the right side of the above formula (3) indicates the amount of heat generated when a current flows through the unit cell 12. Here, I _i is the current value (estimated value) specified by the processing from step S102 to step S106, and R _i is the resistance value calculated by the processing of step S103.

The third term on the right side of the formula (3) indicates the amount of heat released from the unit cell 12 to the periphery of the unit cell 12. Here, T _i (t) indicates the previous battery temperature, and T _ia and R _ia indicate the environmental temperature and the thermal resistance calculated in the process of step S107, respectively. The fourth term on the right side of the above formula (3) indicates the amount of heat released between the two unit cells 12. Here, R _ik indicates the thermal resistance between the two unit cells 12 and can be calculated in advance by experiments or the like.

k is a value from 1 to km and indicates the number of unit cells 12 constituting the battery block 11. When calculating the temperature T _i of the particular unit cell 12, it is necessary to consider the specific unit cell 12, the heat radiation amount between the other of each cell 12. Therefore, according to the above formula (3), the heat radiation amount between the two single cells 12 is defined as the fourth term on the right side of the above formula (3).

As the initial value of the battery temperature T _i, the environmental temperature T _ia calculated in the process of step S107 can be used. That is, assuming that the temperature T _i of the cell 12 is equal to the temperature T _ia around the cell 12, the initial value of the battery temperature T _i can be regarded as the environmental temperature T _ia . The battery temperature T _i calculated in the process of step S108 is used when specifying the resistance value R _0i in the process of step S103.

On the other hand, the controller 40 calculates the SOC _i of each unit cell 12 in step S108. The SOC _i can be calculated based on the following formula (4).

In the above formula (4), q _i indicates a deterioration rate related to the full charge capacity of the unit cell 12. Q indicates the full charge capacity in the initial state and can be measured in advance. As described above, the initial state is a state before the cell 12 is deteriorated. By multiplying the full charge capacity Q by the deterioration rate q _i , the current full charge capacity of the unit cell 12 can be calculated. Here, since the full charge capacity of the single cell 12 tends to decrease as the deterioration of the single cell 12 progresses, the deterioration rate q _i becomes smaller than “1” as the deterioration of the single cell 12 progresses. When the unit cell 12 is not deteriorated, the deterioration rate q _i is “1”.

By dividing the current value I _i during the predetermined time dt by the current full charge capacity of the cell 12, it is possible to calculate the amount of change in the SOC when the current flows through the cell 12. Here, the current value I _i is a value estimated by the processing from step S102 to step S106. When the cell 12 is discharged, the current value I _i becomes a positive value, so the current SOC _i (t + dt) is lower than the previous SOC _i (t). On the other hand, when the unit cell 12 is charged, the current value I _i is a negative value, so the current SOC _i (t + dt) is higher than the previous SOC _i (t).

Note that the initial value of SOC _i can be calculated from the OCV of the unit cell 12. If the OCV of the unit cell 12 is measured, the SOC (SOC _i ) corresponding to the measured OCV can be calculated by using the correspondence relationship between the SOC and the OCV. After calculating the initial value of the SOC _i, based on the equation (4), it is possible to calculate the current SOC _i. The SOC _i calculated in the process of step S108 is used when the resistance value _R0i is specified in the process of step S103 or the OCV _i is calculated in the process of step S104.

In step S109, the controller 40 calculates the deterioration rates r _i and q _i of the unit cells 12. The deterioration rates r _i and q _i can be calculated based on the following formulas (5) and (6).

  In the above formula (5), r represents a deterioration coefficient related to the resistance value of the unit cell 12. The deterioration coefficient r is set according to the current value, the SOC, and the battery temperature. That is, the degradation coefficient r changes according to a change in at least one of the current value, the SOC, and the battery temperature. Specifically, if information indicating the correspondence relationship between the degradation coefficient r, current value, SOC, and battery temperature is obtained through experiments or the like, the degradation coefficient r is identified by identifying the current value, SOC, and battery temperature. be able to.

Here, as the current value, the current value (estimated value) I _i calculated by the processing from step S102 to step S106 is used. As the SOC, the value (SOC _i ) calculated in the process of step S108 is used. The battery temperature, the temperature T _i is used which is calculated by the processing in step S108.

  F (t) shown in the above equation (5) represents a function of time. The time t indicates an accumulated time when the state of the unit cell 12 exists in each section when each of the current value, the SOC, and the battery temperature is divided into a plurality of sections. Regarding each of the current value, the SOC, and the battery temperature, the range of each section can be set as appropriate.

  When each of the current value, the SOC, and the battery temperature in the unit cell 12 indicates a specific value, the time is accumulated for the classification corresponding to the current value, the SOC, and the battery temperature at this time. Here, when at least one of the current value, the SOC, and the battery temperature changes exceeding the category, the category in which the time is accumulated changes.

The memory 41 stores the accumulated time in a state associated with each of the current value, SOC, and battery temperature. This accumulated time is substituted into the function f (t). As described above, since the deterioration coefficient r is set for each section, the deterioration rate r _i for each section can be calculated by multiplying the deterioration coefficient r by the function f (t) in each section. In the present embodiment, the deterioration rates r _i are calculated in all the sections, and these deterioration rates r _i are integrated. The deterioration rate r _i as the integrated value is used when calculating the resistance value R _i in the process of step S103.

The deterioration rate q _i is also calculated in the same manner as the deterioration rate r _i . That is, when each of the current value, the SOC, and the battery temperature is divided into a plurality of sections, the accumulated time when the state of the cell 12 (current value I _i , SOC _i , battery temperature T _i ) exists in each section. Measure. This accumulated time is substituted into the function g (t). In addition, a deterioration coefficient q is set in each section, and the deterioration rate q _i for each section can be calculated by multiplying the deterioration coefficient q by a function g (t) in each section. In this embodiment, the deterioration rates q _i are calculated in all the sections, and these deterioration rates q _i are integrated. The deterioration rate q _i as the integrated value is used when calculating SOC _{i in} the process of step S108.

In this embodiment, a plurality of sections are set for each of the current value, the SOC, and the battery temperature, but the present invention is not limited to this. Specifically, a plurality of categories can be set for at least one of the current value, the SOC, and the battery temperature. Then, in each set section, as in the present embodiment, the deterioration rate (r _i , q _i ) is based on the deterioration coefficient (r, q) and the time function (f (t), g (t)). ) Can be calculated.

In the present embodiment, the current value I _i flowing through each unit cell 12 included in each battery block 11 is estimated by the process shown in FIG. 6, but the present invention is not limited to this. Specifically, the current value I _i flowing through each unit cell 12 included in each battery block 11 can be estimated by the process shown in FIG. The process shown in FIG. 9 is executed by the controller 40 and is repeatedly performed at a predetermined cycle (dt). In the process shown in FIG. 9, the same processes as those shown in FIG. 6 are denoted by the same reference numerals.

In the process shown in FIG. 9, in step S <b> 110, the controller 40 detects the intake air temperature T _input and the exhaust gas temperature T _output based on the outputs of the temperature sensors 51 and 52. The controller 40, in step S110, based on the output of the monitoring unit 20 (monitoring IC 21), for detecting a voltage value _{V j} of each battery block 11. Then, the resistance value R _i of each unit cell 12 is calculated by the process of step S103, and the OCV _{i of} each unit cell 12 is calculated by the process of step S104.

In step S105, the controller 40 calculates the current value I _i of each unit cell 12 based on the above equation (2). Here, the voltage value V _j represented by the above formula (2), the voltage value V _j used detected by the processing of step S110. After calculating the current value I _i , the processing from step S107 to step S109 is performed as in the processing shown in FIG.

In the present embodiment, the current value I _i flowing through each unit cell 12 is estimated based on the processing shown in FIG. 6 or FIG. 9, but the present invention is not limited to this. For example, Japanese Unexamined Patent Application Publication No. 2008-243373 describes a technique for calculating an estimated current value using a battery model. In this technique, the current value I _i flowing through the unit cell 12 can be estimated using the voltage value V _j and the temperature T _i of the unit cell 12 as input values.

By performing the processing shown in FIG. 6 or FIG. 9 and the like, it is possible to estimate the current value I _i flowing through each single battery 12 included in each battery block 11, so that each single unit is based on this current value I _i. The damage amount FD of the fuse 12b included in the battery 12 can be calculated. Specifically, the damage amount FD of the fuse 12b can be calculated based on the following formula (7).

In the above equation (7), FD (t + dt) is the current damage amount, and FD (t) is the previous damage amount. F (I) is the amount of damage generated during the time dt, and changes according to the current value I _i flowing through the fuse 12b.

Here, if the correspondence between the damage amount F (I) and the current value I _i is obtained in advance by experiments or the like, the damage amount F (I) is calculated by estimating the current value I _i as described above. be able to. Generally, as the current value flowing through the fuse 12b increases, the fuse 12b is more likely to deteriorate. Therefore, the damage amount F (I) can be increased as the current value I _i increases. The correspondence relationship between the damage amount F (I) and the current value I _i can be expressed as a map or a function, and information regarding this correspondence relationship can be stored in the memory 41.

In the present embodiment, the damage amount F (I) of the fuse 12b is calculated from the current value I _i flowing through the fuse 12b, but is not limited thereto. For example, the damage amount F (I, T) can be calculated in consideration of not only the current value I _i but also the temperature of the fuse 12b. Specifically, if the correspondence relationship between the current value I _i , the fuse temperature and the damage amount F (I, T) is obtained in advance by experiments or the like, the damage amount F can be determined by specifying the current value I _i and the fuse temperature. (I, T) can be calculated.

In the process shown in FIG. 6 or FIG. 9, the environmental temperature T _ia of the unit cell 12 is calculated. For this reason, the temperature of the fuse 12b can be calculated based on the environmental temperature _Tia . Here, when housing the fuse 12b in the battery case, as the temperature of the fuse 12b, it is also possible to use a temperature T _i of the cell 12.

  If the damage amount FD of the fuse 12b increases, the fuse 12b is likely to be blown, and therefore it is preferable to limit the value of the current flowing through the fuse 12b. Specifically, it is preferable to limit the discharge current when discharging the assembled battery 10, and it is preferable to limit the charging current when charging the assembled battery 10.

  Thus, charging / discharging of the assembled battery 10 can be controlled based on the damage amount FD of each fuse 12b. FIG. 10 shows a process for controlling the discharge of the battery pack 10 based on the damage amount FD of the fuse 12b. The process shown in FIG. 10 is executed by the controller 40.

In step S201, the controller 40 calculates the damage amount FD of each fuse 12b. The damage amount FD is calculated based on the above formula (7). When the current value I _i varies among the plurality of unit cells 12 included in the battery block 11, the damage amount FD of the fuse 12b included in the unit cell 12 also varies.

In step S202, the controller 40 specifies the largest damage amount FD _max (t) among the damage amounts FD (t) in the plurality of fuses 12b. As described above, when the damage amount FD (t) varies in the plurality of fuses 12b, the largest damage amount FD _max (t) is specified. Here, the damage amount FD _max (t) is the largest damage amount FD (t) in all the fuses 12 b included in the assembled battery 10.

In step S203, the controller 40 specifies a threshold value G _lim (t) at the current time t. Here, the threshold value G _lim (t) will be described with reference to FIG. In FIG. 11, the vertical axis indicates the damage amount FD (t) and the output power of the unit cell 12. Moreover, the horizontal axis of FIG. 11 shows time. G _MAX indicates the maximum value of the damage amount FD (t) allowed in the fuse 12b. That is, the damage amount G _MAX is the damage amount FD (t) when the fuse 12b reaches the end of its life.

When the unit cell 12 (or vehicle) reaches a preset life, the damage amount FD (t) can reach the damage amount G _MAX . Thereby, the lifetime of the fuse 12b can be matched with the lifetime of the unit cell 12 (or vehicle). The lifetime of the unit cell 12 (or vehicle) can be defined as time t _MAX . The time t _MAX indicates an elapsed time from when the single battery 12 (or vehicle) is used for the first time. For this reason, when the elapsed time reaches the time t _MAX , the unit cell 12 (or vehicle) has a lifetime.

The allowable damage amount G (t) is the maximum value of the allowable damage amount FD (t) at time t. The allowable damage amount G (t) is determined based on the damage amount G _MAX and the time t _MAX . In FIG. 11, the allowable damage amount G (t) is determined based on a straight line (dashed line) connecting the damage amount FD (t) at time 0 and the damage amount G _MAX at time t _MAX. Is done. According to the alternate long and short dash line shown in FIG. 11, the time t and the allowable damage amount G (t) are in a proportional relationship.

  In the present embodiment, the allowable damage amount G (t) is determined based on the alternate long and short dash line (straight line) shown in FIG. 11, but the present invention is not limited to this. That is, the trajectory indicated by the alternate long and short dash line in FIG. Specifically, the alternate long and short dash line that specifies the allowable damage amount G (t) may be a curved line instead of a straight line.

The threshold G _lim (t) is a value smaller than the allowable damage amount G (t) by a predetermined amount ΔG. The output of the single battery 12 (the assembled battery 10) can be controlled on the basis of the allowable damage amount G (t). In this case, the damage amount FD _max (t) is the allowable damage amount due to a control delay or the like. There is a possibility that it may be larger than G (t).

Therefore, in this embodiment, the output of the unit cell 12 (the assembled battery 10) is controlled with reference to a threshold G _lim (t) smaller than the allowable damage amount G (t). Thereby, even if the damage amount FD _max (t) becomes larger than the threshold value G _lim (t), the damage amount FD _max (t) can be prevented from reaching the allowable damage amount G (t).

Here, the difference ΔG between the allowable damage amount G (t) and the threshold G _lim (t) can be set as appropriate. In addition, you may control the output of the cell 12 (assembled battery 10) on the basis of the allowable damage amount G (t).

As described above, the threshold G _lim (t) is set in advance based on the allowable damage amount G (t). For this reason, information regarding the threshold value G _lim (t) can be stored in the memory 41. The controller 40 can specify the threshold value G _lim (t) corresponding to the measurement time t by measuring the current time t. Here, the current time t is an elapsed time since the unit cell 12 (the assembled battery 10) is used for the first time, and can be measured using a timer. In the process of step S203, the threshold value G _lim (t) is specified as described above.

In step S204, the controller 40 determines whether or not the damage amount FD _max (t) specified in the process of step S202 is larger than the threshold value G _lim (t) specified in the process of step S203. If the damage amount FD _max (t) is larger than the threshold value G _lim (t), the controller 40 performs the process of step S205. On the other hand, if the damage amount FD _max (t) is smaller than the threshold value G _lim (t), the controller 40 performs the process of step S210.

Here, when the damage amount FD _max (t) is larger than the threshold value G _lim (t), the controller 40 determines that it is necessary to limit the output of the unit cell 12 (the assembled battery 10), and after step S205. Process. By limiting the output of the unit cell 12 (the assembled battery 10), the current flowing through the fuse 12b can be suppressed, and the progress of the deterioration of the fuse 12b can be suppressed. In this manner, the damage amount FD _max (t) can be reduced below the threshold G _lim (t) by suppressing the progress of deterioration of the fuse 12b.

In step S205, the controller 40 specifies the allowable damage amount G (t) at the current time t. As described above, the allowable damage amount G (t) is set in advance based on the damage amount G _MAX and the time t _MAX . For this reason, information regarding the allowable damage amount G (t) can be stored in the memory 41. That is, the correspondence between the elapsed time t after the first use of the unit cell 12 and the allowable damage amount G (t) can be stored in the memory 41. Thereby, the controller 40 can specify the allowable damage amount G (t) corresponding to the current time t by measuring the time t until the present time.

In step S206, the controller 40 calculates the maximum output power W _{out, max} (t) allowed at time t. The output power W _{out, max} (t) is calculated based on the following equation (8).

In the above formula (8), W _{out, MAX} is the maximum power value obtained when the battery pack 10 is discharged. The output power W _{out, MAX} is set in advance based on the output characteristics of the battery pack 10. Here, information on the output power W _{out, MAX} can be stored in the memory 41. W _limit is the amount of power when limiting the output of the battery pack 10. As can be seen from the above equation (8), when the output of the battery pack 10 is limited, the output power W _{out, max} (t) is lower than the output power W _{out, MAX} by the _limit power amount W _limit. .

The limit power amount W _limit can be calculated based on, for example, the following formula (9).

In the above equation (9), FD _max (t) indicates the maximum amount of damage at time t, and G _limit (t) indicates the threshold value at time t. k represents a weighting coefficient and can be set as appropriate. The weighting coefficient k can be stored in the memory 41.

According to the above equation (9), the limit power amount W _limit is determined according to the difference between the threshold value G _limit (t) and the damage amount FD _max (t). If the limited power amount W _limit is determined in this way, the difference between the threshold value G _limit (t) and the damage amount FD _max (t) can be reflected in the process of limiting the output of the assembled battery 10. That is, as the difference between the damage amount FD _max (t) and the threshold value G _limit (t) increases, the limit power amount W _limit increases and the output of the assembled battery 10 is more likely to be limited. In other words, as the difference between the damage amount FD _max (t) and the threshold value G _limit (t) becomes smaller, the limit power amount W _limit decreases and the output of the assembled battery 10 becomes less likely to be restricted.

In step S207, the controller 40 specifies the output power W _out (t) required for the assembled battery 10. For example, the required output power W _out (t) increases as the accelerator pedal of the vehicle is pushed. In step S208, the controller 40 determines whether or not the output power W _out (t) specified in the process of step S207 is higher than the output power W _{out, max} (t) calculated in the process of step S206. To do.

When the output power W _out (t) is higher than the output power W _{out, max} (t), the controller 40 performs the process of step S209. On the other hand, when the output power W _out (t) is lower than the output power W _{out, max} (t), the controller 40 performs the process of step S210. In step S210, the controller 40, as the actual output power _{W out} of the assembled battery 10 (t), sets the required output power _{W out} (t).

When the process proceeds from step S208 to step S209, the required output power W _out (t) is higher than the output power W _{out, max} (t). For this reason, if the actual output power W _out (t) of the assembled battery 10 is set to the output power W _{out, max} (t) in the process of step S209, the actual output power W _out (t) is required. Output power W _out (t). That is, the output of the assembled battery 10 is limited.

In step S210, the controller 40, as the actual output power _{W out} of the assembled battery 10 (t), sets the required output power _{W out} (t). When the process proceeds from step S208 to step S210, the required output power W _out (t) is lower than the output power W _{out, max} (t). Here, the output power W _{out, max} (t) is the maximum output power in consideration of the damage amount FD _max (t).

For this reason, if the required output power W _out (t) is lower than the output power W _{out, max} (t), the actual output power W _out (t) of the assembled battery 10 is allowed while allowing the fuse 12b to deteriorate. The required output power W _out (t) can be set as Thus, in the process of step S210, the output of the assembled battery 10 is not limited.

Here, the output of the assembled battery 10 is not limited even when the process proceeds from step S204 to step S210. When the process proceeds from the process of step S204 to the process of step S210, the damage amount FD _max (t) has not reached the threshold value G _limit (t). For this reason, an increase in the damage amount FD _max (t) can be allowed, and there is no need to limit the output of the assembled battery 10.

FIG. 11 is a diagram (an example) showing changes in the damage amount FD _max (t) and changes in the output power W _{out, max} (t) when the processing shown in FIG. 10 is performed. As shown in FIG. 11, when the damage amount FD _max (t) becomes larger than the threshold value G _limit (t), the output power W _{out, max} (t) becomes lower than the output power W _{out, MAX} , and the assembled battery 10 outputs are limited.

As described above, if the output of the assembled battery 10 is limited, it is difficult for current to flow through the fuse 12b, and the deterioration of the fuse 12b can be suppressed. Accordingly, the damage amount FD _max (t) can be made smaller than the threshold value G _limit (t). If the damage amount FD _max (t) is smaller than the threshold value G _limit (t), the output restriction of the assembled battery 10 is released. That is, the output power W _{out, max} (t) is set to the output power W _{out, MAX} . Thereby, the output of the assembled battery 10 can be controlled while monitoring the damage amount FD _max (t) of each fuse 12b.

Further, according to the present embodiment, the damage amount FD _max (t) can be changed along the threshold value G _limit (t). Thereby, it is possible to continue using the fuse 12b without blowing it, unless it is necessary to blow the fuse 12b until the time t _{MAX at} which the assembled battery 10 (or vehicle) reaches the end of life.

In the process shown in FIG. 10, the output of the assembled battery 10 is controlled based on the magnitude relationship between the damage amount FD _max (t) and the threshold value G _limit (t), but the present invention is not limited to this. Specifically, the input of the assembled battery 10 can be controlled based on the magnitude relationship between the damage amount FD _max (t) and the threshold value G _limit (t). Even when the battery pack 10 is input, a current flows through the fuse 12b, causing the fuse 12b to deteriorate. Therefore, the input of the assembled battery 10 can be controlled based on the damage amount FD _max (t).

  FIG. 12 is a flowchart showing a process when the input of the assembled battery 10 is controlled. The process shown in FIG. 12 is executed by the controller 40.

The processing from step S301 to step S305 is the same as the processing from step S201 to step S205 shown in FIG. In step S306, the controller 40 calculates the maximum input power W _{in, max} (t) allowed at time t. The input power W _{in, max} (t) is calculated based on the following equation (10).

In the above formula (10), Win _{, MAX} is the maximum power value obtained when charging the assembled battery 10. W _limit is the amount of electric power when the input of the battery pack 10 is limited. As can be seen from the above equation (10), when the input of the battery pack 10 is limited, the input power W _{in, max} (t) is lower than the input power W _{in, MAX} by the _limit power amount W _limit. . The limited power amount W _limit can be determined according to the difference between the threshold value G _limit (t) and the damage amount FD _max (t), similarly to the above equation (9).

If the limited power amount W _limit is determined in this way, the difference between the threshold value G _limit (t) and the damage amount FD _max (t) can be reflected in the process of limiting the input of the assembled battery 10. That is, as the difference between the damage amount FD _max (t) and the threshold value G _limit (t) increases, the limit power amount W _limit increases and the input of the assembled battery 10 is more likely to be limited. Further, as the difference between the damage amount FD _max (t) and the threshold value G _limit (t) increases, the limit power amount W _limit decreases, and the input of the assembled battery 10 is less likely to be limited.

In step S307, the controller 40 specifies the power W _in (t) input to the assembled battery 10. In step S308, the controller 40 determines whether or not the input power W _in (t) specified in step S307 is higher than the input power W _{in, max} (t) calculated in step S306. To do.

When the input power W _in (t) is higher than the input power W _{in, max} (t), the controller 40 performs the process of step S309. On the other hand, when the input power W _in (t) is lower than the input power W _{in, max} (t), the controller 40 performs the process of step S310. In step S310, the controller 40, as the actual input power _W in the assembled battery 10 (t), setting the power _W in (t) to be input.

When the process proceeds from step S308 to step S309, the input power W _in (t) is higher than the allowable maximum input W _{in, max} (t). Therefore, in the process of step S309, the input power _{W in} the actual input power _W in (t) of the assembled battery _10, is set to _max (t), actual input power _W in (t) will try to enter It becomes lower than the power W _in (t). That is, the input of the assembled battery 10 is limited.

In step S310, the controller 40, as the actual input power _W in the assembled battery 10 (t), setting the power _W in (t) to be input. When the process proceeds from step S308 to step S310, the power W _in (t) to be input is lower than the input power W _{out, max} (t). The input power W _{out, max} (t) is the maximum input power considering the damage amount FD _max (t).

For this reason, if the power W _in (t) to be input is lower than the input power W _{in, max} (t), the power W _out to be input as the actual input power W _out (t) of the battery pack 10. (T) can be set. Thus, in the process of step S310, the input of the assembled battery 10 is not limited.

Here, when the process proceeds from the process of step S304 to the process of step S310, the input of the assembled battery 10 is not limited. When the process proceeds from the process of step S304 to the process of step S310, the damage amount FD _max (t) has not reached the threshold value G _limit (t). For this reason, an increase in the damage amount FD _max (t) can be allowed, and there is no need to limit the input of the assembled battery 10.

FIG. 13 is a diagram (an example) showing a change in the damage amount FD _max (t) and a change in the input power Win _{, max} (t) when the process shown in FIG. 12 is performed. As shown in FIG. 13, when the damage amount FD _max (t) becomes larger than the threshold value G _limit (t), the input power W _{in, max} (t) becomes lower than the input power Win _{, MAX} , and the assembled battery Ten inputs are limited.

When the input of the assembled battery 10 is restricted, it is difficult for a current to flow through the fuse 12b, and the deterioration of the fuse 12b can be suppressed. Accordingly, the damage amount FD _max (t) can be made smaller than the threshold value G _limit (t). If the damage amount FD _max (t) is smaller than the threshold value G _limit (t), the input restriction of the assembled battery 10 is released. That is, the input power Win _{, max} (t) is set to the input power Win _{, MAX} . Thereby, the input of the assembled battery 10 can be controlled while monitoring the damage amount FD _max (t) of each fuse 12b.

10: assembled battery (power storage device), 11: battery block (power storage block),
12: single cell (storage element), 12a: power generation element, 12b: fuse, 13: case,
13a: intake port, 13b: exhaust port, 14: partition plate, 15: intake duct,
16: Exhaust duct, 20: Monitoring unit (voltage sensor),
21: Monitoring IC (voltage sensor), 31: Current sensor, 32: Booster circuit,
33: Inverter, 34: Motor generator, 40: Controller, 41: Memory,
50: Fan, 51, 52: Temperature sensor, PL: Positive line, NL: Negative line,
R: current limiting resistor, SMR-B, SMR-G, SMR-P: system main relay

Claims (7)

A power storage device including a plurality of power storage elements connected in parallel;
A plurality of fuses connected in series with each of the plurality of power storage elements;
A controller for controlling charging and discharging of the power storage device,
The controller is
Using the voltage values of the plurality of power storage elements and the internal resistance of each power storage element, the current value flowing through each power storage element is calculated,
A power storage system that restricts at least one of charging and discharging of the power storage device when a damage amount of each fuse corresponding to the calculated current value is larger than a threshold value.   The power storage system according to claim 1, wherein the controller calculates a damage amount of each fuse using a relationship in which the damage amount increases as the current value increases.   3. The power storage system according to claim 1, wherein the controller sets a limit amount according to a difference between the damage amount and the threshold when limiting at least one of charging and discharging of the power storage device. .   The controller limits at least one of charging and discharging of the power storage device when the largest damage amount among the damage amounts in the plurality of fuses is larger than the threshold value. The electrical storage system as described in any one of these.   The power storage device according to any one of claims 1 to 4, wherein the power storage device includes a plurality of power storage blocks that are respectively configured by the plurality of power storage elements connected in parallel and connected in series. system. A current sensor for detecting a current value flowing through the power storage device;
In the plurality of power storage elements connected in parallel, the controller is configured to calculate a current value as a current value flowing through each power storage element when a total sum of calculated current values is equal to a current value detected by the current sensor. The power storage system according to claim 1, wherein a value is used. Having a voltage sensor for detecting a voltage value in the plurality of power storage elements connected in parallel;
The said controller calculates the electric current value which flows into each said electrical storage element using the internal resistance of each said electrical storage element, and the voltage value detected by the said voltage sensor, Any one of Claim 1 to 5 characterized by the above-mentioned. The electrical storage system as described in any one.