Battery pack

Abstract

To provide a battery pack that detects individual deterioration of battery cells and switches the use of the battery cells in accordance with the deterioration.SOLUTION: A battery pack 1 comprises: a series circuit 2 in which a plurality of unit modules EM having battery cells Ce is connected in series; a detection device 3 that detects a deterioration state of each of the battery cells Ce; and a control device 4 that controls the series circuit 2. Each of the unit modules EM includes: a first terminal T1 and a second terminal T2; and a switching circuit SW for switching connection states including a joined state and a withdrawal state. The detection device 3 includes: a parameter detection section 31 for detecting a parameter value PV of a parameter related to a state of each of the battery cells Ce; and a state estimation section 33 for estimating the deterioration state of the battery cell Ce for each of the unit modules EM on the basis of the parameter value PV. The control device 4 controls switching of the connection states by each of the switching circuits SW on the basis of estimation information for each of the unit modules EM estimated by the state estimation section 33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery pack that selects a battery cell to output power in consideration of the deterioration state of the battery cell. [Background technology]

[0002] In recent years, modular multilevel converters (MMCs), which combine modules in which multiple submodules are connected in series, have been used as inverters for DC-AC conversion (see, for example, Patent Document 1). Modular multilevel converters are capable of outputting any output voltage by integrating the terminal voltages of energy storage elements such as capacitors included in the submodules. Inverters using modular multilevel converters are suitable for use in electrically powered vehicles such as electric vehicles and hybrid vehicles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-012769 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional battery packs, multiple battery cells are connected in series. Each battery cell deteriorates at a different rate due to its own characteristics. However, because the battery cells are connected in series, it is difficult to detect the deterioration of each cell individually. For this reason, conventional battery packs are replaced if the performance of the entire battery pack deteriorates, even if some battery cells are not severely deteriorated, which shortens the usable life of the battery pack.

[0005] The present invention provides a battery pack that detects the deterioration of each battery cell individually and switches the use of the battery cells depending on the deterioration. [Means for solving the problem]

[0006] A battery pack according to the present invention comprises a series circuit in which a plurality of unit modules having battery cells are connected in series, a detection device that detects a deterioration state of each of the battery cells, and a control device that controls the series circuit, wherein each of the unit modules includes a first terminal and a second terminal, and a switching circuit that switches connection states including an connected state in which the battery cell is connected between the first terminal and the second terminal, and a disconnected state in which the first terminal and the second terminal are short-circuited, and the detection device includes a parameter detection unit that detects one or more parameter values ​​related to the state of each of the cells, and a state estimation unit that estimates the deterioration state of the battery cells for each of the unit modules based on the parameter values ​​detected by the parameter detection unit, and the control device controls the switching of the connection state by each of the switching circuits based on the estimation information for each of the unit modules estimated by the state estimation unit.

[0007] In this battery pack configuration according to the present invention, the parameter detection unit and the state estimation unit detect parameter values ​​and estimate the state of deterioration for each unit module, thereby switching the use of each battery cell according to the degree of deterioration, thereby suppressing battery cell deterioration and extending the usable life of the battery pack. Furthermore, when it is estimated that a battery cell is deteriorated, the battery cell can be switched to a detached state in the unit module, allowing replacement of each unit module or each battery cell, facilitating recycling.

[0008] It is also preferable that the parameter detection unit accumulates the addition time in the addition state for each unit module as the parameter value, and the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the addition time.

[0009] It is also preferable that the parameter detection unit accumulates, as the parameter value, the number of times that the switching circuit switches the connection state during the period in which the battery pack is in use, for each unit module, and the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the number of times that the switching circuit switches the connection state.

[0010] With such a battery pack configuration, it is possible to estimate the deterioration of each battery cell without knowing in advance the deterioration characteristics of the battery cells of each unit module.

[0011] It is also preferable that the parameter detection unit detects the voltage of each of the unit modules and the current of each of the unit modules as the parameter values, calculates the internal resistance of the battery cells for each of the unit modules based on the detected voltage information and current information, and the state estimation unit estimates the degradation state of the battery cells for each of the unit modules based on the internal resistance.

[0012] With this battery pack configuration, the internal resistance of the battery cell can be calculated in a pseudo manner by detecting the voltage and current of the unit module, and the deterioration state of the battery cell can be estimated from the magnitude of the internal resistance.

[0013] It is also preferable that the parameter detection unit detects the voltage of each of the unit modules and the current of each of the unit modules as the parameter values, calculates the amount of output power of the battery cells for each of the unit modules based on the detected voltage information and current information, and the state estimation unit estimates the deterioration state of the battery cells for each of the unit modules based on the amount of output power.

[0014] With this battery pack configuration, the output power of the battery cell is calculated by detecting the voltage and current of the unit module, and the deterioration state of the battery cell can be inferred from the amount of output power.

[0015] It is also preferable that the parameter detection unit detects the voltage of each of the unit modules and the current of each of the unit modules as the parameter values, calculates the output power amount and input power amount of the battery cell for each of the unit modules based on the detected voltage information and current information, respectively, and the state estimation unit estimates the deterioration state of the battery cell for each of the unit modules based on the input power amount and the output power amount.

[0016] With this battery pack configuration, the output power and input power of the battery cell are calculated by detecting the voltage and current of the unit module, and the deterioration state of the battery cell can be inferred from the difference between the output power and input power.

[0017] It is also preferable that the parameter detection unit detects the current of each of the unit modules as the parameter value, and integrates the integrated current flowing through the battery cells for each of the unit modules based on the detected current information, and the state estimation unit estimates the degradation state of the battery cells for each of the unit modules based on the integrated current.

[0018] With this battery pack configuration, the deterioration state of the battery cells can be estimated from the magnitude of the current integrated value.

[0019] It is also preferable that the parameter detection unit detects a cell temperature, which is the temperature of the battery cell, for each unit module as the parameter value, and the state estimation unit estimates the deterioration state of the battery cell for each unit module based on the cell temperature.

[0020] With this battery pack configuration, the deterioration state of the battery cells can be estimated from the cell temperatures detected in the battery cells. [Effects of the Invention]

[0021] Such a battery pack can detect the deterioration of each battery cell individually and switch the use of the battery cells according to the deterioration, thereby suppressing the deterioration of the battery cells and extending the usable life of the battery pack. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a block diagram showing an example of the configuration of a battery pack according to an embodiment of the present invention; [Figure 2] FIG. 2 is a conceptual circuit diagram showing an example of the configuration of the unit module shown in FIG. [Figure 3] FIG. 10 is a conceptual circuit diagram showing an example of a unit module using a full bridge as a switching circuit. [Figure 4] FIG. 1 is a conceptual circuit diagram showing each unit module in a series circuit. [Figure 5] 10 is a graph showing the joining time of each unit module during the usage period of the battery pack. [Figure 6] 10 is a graph showing the number of times each unit module is switched during the use period of the battery pack. [Figure 7] 6 is a graph showing the internal resistance of the battery cells of each unit module during the use period of the battery pack. [Figure 8] 10 is a graph showing the amount of output power of each unit module during the use period of the battery pack. [Figure 9] 10 is a graph showing the difference in input / output power of each unit module during the use period of the battery pack. [Figure 10] 10 is a graph showing the integrated current of each unit module during the use period of the battery pack. [Figure 11] 6 is a graph showing the cell temperatures of the battery cells of each unit module during the use period of the battery pack. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, a battery pack 1 according to an embodiment of the present invention will be described with reference to the drawings. Note that components with the same reference numerals in the various drawings are the same components, and their description will be omitted.

[0024] As shown in Fig. 1, the battery pack 1 includes a series circuit 2, a detection device 3, and a control device 4, and a high-potential side power line WH and a low-potential side power line WL extend therethrough. A plurality of unit modules EM are connected in series to the series circuit 2, and each unit module has a battery cell Ce. Note that although the series circuit 2 shown in Fig. 1 only shows a configuration in which a plurality of unit modules EM are connected in series, the series circuit 2 may include other components as long as a plurality of unit modules EM are connected in series.

[0025] As shown in Fig. 2, the unit module EM includes a first terminal T1, a second terminal T2, a battery cell Ce for storing electric charge, and a switching circuit SW. Various secondary batteries can be suitably used as the battery cell Ce, and are not limited to single cells. A battery pack made up of a combination of multiple secondary batteries can also be used as the battery cell Ce. The switching circuit SW is a circuit that switches the electrical connection state between the battery cell Ce and the first terminal T1 and second terminal T2, and is configured, for example, by a half-bridge circuit made up of switching elements SW1 and SW2 as shown in Fig. 2.

[0026] Specifically, the battery cell Ce and the switching element SW1 are connected in series, and the circuit in which the battery cell Ce and the switching element SW1 are connected in series is connected in parallel to the switching element SW2. The connection point of the switching elements SW1 and SW2 is connected to the first terminal T1, and the connection point of the switching element SW2 and the battery cell Ce is connected to the second terminal T2.

[0027] The first terminal T1 is connected to the second terminal T2 of the unit module EM on the higher potential side than the unit module EM, and the second terminal T2 is connected to the first terminal T1 of the unit module EM on the lower potential side than the unit module EM. As a result, the series circuit 2 is formed by connecting a plurality of unit modules EM in series, and the first terminal T1 of the unit module EM on the highest potential side in the series circuit 2 extends from the battery pack 1 as a power line WH, and the second terminal T2 of the unit module EM on the lowest potential side in the series circuit 2 extends from the battery pack 1 as a power line WL.

[0028] Various switching elements can be used as the switching elements SW1 and SW2, and for example, semiconductor switching elements such as transistors can be suitably used. The switching elements SW1 and SW2 may be any elements that can be turned on and off in response to a control signal from the control device 4.

[0029] When the unit module EM receives an on / off control signal from the control device 4, the connection state is switched between a join state and a disconnect state by the switching circuit SW, as shown in Figure 2. The connection state of the unit module EM indicated by symbol A is the join state, and the connection state of the unit module EM indicated by symbol B is the disconnect state. In the join state unit module EM, the switching element SW1 is on and the switching element SW2 is off, so that the battery cell Ce is joined to the series circuit 2. In the disconnect state unit module EM, the switching element SW1 is off and the switching element SW2 is on, so that the battery cell Ce is disconnected from the series circuit 2.

[0030] Furthermore, the unit module EM may use a full-bridge circuit as the switching circuit SW, as shown in Fig. 3. The unit module EM of the full-bridge circuit shown in Fig. 3 further includes switching elements SW3 and SW4 in addition to the switching elements SW1 and SW2 shown in Fig. 2. The switching elements SW3 and SW4 may be the same as the switching elements SW1 and SW2.

[0031] Specifically, a circuit in which switching elements SW3 and SW4 are connected in series is connected in parallel to a circuit in which switching elements SW1 and SW2 are connected in series. The connection point of switching elements SW1 and SW2 is connected to a first terminal T1, and the connection point of switching elements SW3 and SW4 is connected to a second terminal T2. Similar to the switching circuit SW of the half-bridge circuit, switching elements SW1, SW2, SW3, and SW4 are turned on and off in response to control signals from the control device 4.

[0032] When the unit modules EM of the full-bridge circuit receive an on / off control signal from the control device 4, the connection state is switched by the switching circuit SW among an add-on state, a disconnection state, and an inverted state, as shown in Fig. 3. In addition to the add-on state indicated by symbol A and the disconnection state indicated by symbol B, the connection state of the unit module EM indicated by symbol C is an inverted state. A unit module EM in the inverted state reverses the polarity of the battery cell Ce in the series circuit 2 and is connected to another unit module EM, i.e., another battery cell Ce.

[0033] In the add-on state, switching elements SW1 and SW4 are on, and switching elements SW2 and SW3 are off. In the remove-on state, switching elements SW1 and SW3 are off, and switching elements SW2 and SW4 are on. In the inverted state, switching elements SW1 and SW4 are off, and switching elements SW2 and SW3 are on. Note that in the remove-on state, switching elements SW1 and SW3 may be on, and switching elements SW2 and SW4 may be off.

[0034] The detection device 3 is composed of, for example, a CPU such as a microprocessor that executes predetermined logical operations, a memory such as RAM that temporarily stores data, and peripheral circuits for these, and operates by executing a predetermined program.

[0035] The detection device 3 includes a parameter detection unit 31 and a state estimation unit 33. The parameter detection unit 31 detects parameter values ​​of parameters related to the state of the battery cells Ce in each unit module EM. The state estimation unit 33 estimates the degradation state of the battery cells Ce for each unit module EM based on the parameter values ​​PV detected in each unit module EM.

[0036] The control device 4 is composed of, for example, a CPU such as a microprocessor that executes predetermined logical operations, a memory such as RAM that temporarily stores data, and peripheral circuits for these, and operates by executing a predetermined program.

[0037] The control device 4 turns on and off the switching elements SW1 and SW2 based on the estimation information for each unit module EM estimated by the state estimation unit 33, thereby controlling the connection state of each unit module EM of the battery pack 1. Hereinafter, the control of the control device 4 to control the connection state including the add-on state and the disconnection state by controlling the switching elements SW1 and SW2, or the control of the control device 4 to control the connection state including the add-on state, the disconnection state, and the inverted state by controlling the switching elements SW1 to SW4 may be simply referred to as controlling the connection state.

[0038] The parameter detection unit 31 and the state estimation unit 33 in the detection device 3 will be described below. To facilitate the description, the following assumptions are made as premises: the unit module EM uses a half bridge, and the series circuit 2 included in the battery pack 1 includes eight unit modules EM1 to EM8 as shown in FIG. 4. Therefore, in the following description of the unit modules EM, the unit modules EM1 to EM8 may be used.

[0039] The above assumed conditions are set for the convenience of explanation, and the battery pack 1 is not limited to these assumed conditions.

[0040] The parameter detection unit 31 detects a parameter value PV of one or more parameters relating to the state of each battery cell Ce in the unit modules EM1 to EM8. The parameters relating to the state of each battery cell Ce in the unit modules EM1 to EM8 may be any parameters required for the state estimation unit 33 to estimate the degradation state of the battery cells Ce in the unit modules EM.

[0041] The parameter detection unit 31 uses, as a parameter, the addition time P1, which is the time during which the connection state of the unit module EM is maintained in an addition state, as shown in Fig. 5, for example. The parameter detection unit 31 accumulates the parameter value PV for the addition time P1 for each of the unit modules EM1 to EM8 during the period in which the battery pack 1 is used, such as during discharging and charging. The state estimation unit 33 relatively compares the parameter value PV for the addition time P1 for each of the unit modules EM1 to EM8 as shown in Fig. 5, and infers, for example, that the battery cell Ce of the unit module EM with the smallest parameter value PV for the addition time P1 is degraded. In the case of the results shown in Fig. 5, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 is degraded because the parameter value PV for the addition time P1 of the unit module EM4 is the smallest.

[0042] Furthermore, the parameter detection unit 31 uses, as a parameter, the number of switching times P2, which is the number of times the connection state of the unit module EM has been switched, as shown in Fig. 6, for example. The parameter detection unit 31 accumulates the parameter value PV of the number of switching times P2 for each of the unit modules EM1 to EM8 during the usage period of the battery pack 1. The state estimation unit 33 relatively compares the parameter values ​​PV of the number of switching times P2 accumulated for each of the unit modules EM1 to EM8 as shown in Fig. 6, and infers, for example, that the battery cell Ce of the unit module EM with the largest parameter value PV of the number of switching times P2 has deteriorated. In the case of the results shown in Fig. 6, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 has deteriorated because the parameter value PV of the number of switching times P2 of the unit module EM4 is the largest.

[0043] As a result, by using the addition time P1 and the number of switching times P2 as indicators for estimating the deterioration state of the battery cells Ce, it is possible to estimate the deterioration of each battery cell Ce without having to know in advance the deterioration characteristics of the battery cells Ce possessed by each unit module EM1 to EM8, thereby simplifying the work.

[0044] Furthermore, the parameter detection unit 31 uses the internal resistance P3 of the battery cells Ce in the unit modules EM as a parameter, for example, as shown in Fig. 7. Each of the unit modules EM1 to EM8 includes a voltage sensor (not shown) that detects the terminal voltage of the unit module EM, i.e., the terminal voltage of the battery cells Ce, and a current sensor (not shown) that detects the intra-module current flowing within the unit module EM, i.e., the current flowing into the battery cells Ce. The parameter detection unit 31 calculates a parameter value PV of the internal resistance P3 of each battery cell Ce during the usage period of the battery pack 1, based on the voltage detected by each voltage sensor and the current detected by each current sensor. The state estimation unit 33 relatively compares the parameter values ​​PV of the internal resistance P3 calculated for each of the unit modules EM1 to EM8 as shown in Fig. 7, and estimates, for example, that the battery cells Ce of a unit module EM with a larger parameter value PV of the internal resistance P3 are degraded. In the case of the results shown in FIG. 7, the state inferring unit 33 infers that the battery cell Ce of the unit module EM4 has deteriorated because the parameter value PV of the internal resistance P3 of the unit module EM4 is the highest.

[0045] As a result, the parameter detection unit 31 calculates the internal resistance P3 of each battery cell Ce during the usage period based on the voltage and current detected by the voltage sensor and current sensor, and the magnitude of each internal resistance P3 can be compared relatively to estimate the deterioration state of the battery cells Ce in each unit module EM1 to EM8.

[0046] Furthermore, the parameter detection unit 31 uses the output power P4 of the battery cell Ce in the unit module EM as a parameter, for example, as shown in FIG. 8. As described above, each of the unit modules EM1 to EM8 includes a voltage sensor and a current sensor. The parameter detection unit 31 calculates a parameter value PV of the output power P4 of each battery cell Ce during the usage period of the battery pack 1, based on the voltage detected by each voltage sensor and the current detected by each current sensor. The state estimation unit 33 relatively compares the parameter values ​​PV of the output power P4 calculated for each of the unit modules EM1 to EM8 as shown in FIG. 8, and infers, for example, that the battery cell Ce of the unit module EM with the smallest parameter value PV of the output power P4 is degraded. In the case of the results shown in FIG. 8, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 is degraded because the parameter value PV of the output power P4 of the unit module EM4 is the smallest.

[0047] As a result, the parameter detection unit 31 calculates the output power P4 of each unit module EM1 to EM8 during the usage period based on the voltage and current detected by the voltage sensor and current sensor, and the magnitude of each output power P4 can be compared relatively to estimate the deterioration state of the battery cells Ce in each unit module EM1 to EM8.

[0048] Furthermore, the parameter detection unit 31 uses, as a parameter, for example, the input / output power difference P5 of the battery cell Ce in the unit module EM, as shown in FIG. 9. As described above, each of the unit modules EM1 to EM8 includes a voltage sensor and a current sensor. The parameter detection unit 31 calculates a parameter value PV of the input / output power difference P5, which is the difference between the amount of input power to the battery cell Ce and the amount of output power from the battery cell Ce, during the usage period of the battery pack 1, based on the voltage detected by each voltage sensor and the current detected by each current sensor. The state estimation unit 33 relatively compares the parameter values ​​PV of the input / output power difference P5 calculated for each of the unit modules EM1 to EM8 as shown in FIG. 9, and infers, for example, that the battery cell Ce of the unit module EM with the largest parameter value PV of the input / output power difference P5 is degraded. In the case of the results shown in FIG. 9, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 is degraded because the parameter value PV of the input / output power difference P5 of the unit module EM4 is the largest.

[0049] As a result, the parameter detection unit 31 calculates the input / output power difference P5 of each unit module EM1 to EM8 during the usage period based on the voltage and current detected by the voltage sensor and current sensor, and the magnitude of each input / output power difference P5 can be relatively compared to estimate the deterioration state of the battery cells Ce in each unit module EM1 to EM8.

[0050] Furthermore, the parameter detection unit 31 uses, as a parameter, an integrated current P6, calculated by integrating the absolute value of the current flowing into the battery cell Ce in the unit module EM, as shown in FIG. 10. As described above, each of the unit modules EM1 to EM8 includes a current sensor. The parameter detection unit 31 calculates a parameter value PV of the integrated current P6 of the battery cell Ce during the usage period of the battery pack 1, based on the current detected by each current sensor. The state estimation unit 33 relatively compares the parameter values ​​PV of the integrated current P6 calculated for each of the unit modules EM1 to EM8 as shown in FIG. 10, and infers, for example, that the battery cell Ce of the unit module EM with the largest parameter value PV of the integrated current P6 is degraded. In the case of the results shown in FIG. 10, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 is degraded because the parameter value PV of the integrated current P6 of the unit module EM4 is the largest.

[0051] As a result, the parameter detection unit 31 calculates the integrated current P6 of each battery cell Ce during the usage period based on the current detected by the current sensor, and the magnitude of each integrated current P6 can be compared relatively to estimate the deterioration state of the battery cells Ce in each unit module EM1 to EM8.

[0052] Furthermore, the parameter detection unit 31 uses, as a parameter, for example, cell temperature P7, which is the temperature of the battery cell Ce in the unit module EM, as shown in FIG. 11. Each of the unit modules EM1 to EM8 includes a temperature sensor that measures the temperature of the battery cell Ce in the unit module EM. The parameter detection unit 31 detects a parameter value PV of the cell temperature P7 of each battery cell Ce during the usage period of the battery pack 1, based on the temperature detected by each temperature sensor. The state estimation unit 33 relatively compares the parameter values ​​PV of the cell temperature P7 detected for each of the unit modules EM1 to EM8 as shown in FIG. 11, and infers, for example, that the battery cell Ce of the unit module EM with the largest parameter value PV of the cell temperature P7 is degraded. In the case of the results shown in FIG. 11, the state estimation unit 33 infers that the battery cell Ce of the unit module EM4 is degraded because the parameter value PV of the cell temperature P7 of the unit module EM4 is the highest.

[0053] As a result, the parameter detection unit 31 calculates the cell temperature P7 of each battery cell Ce during the usage period based on the temperature detected by the temperature sensor, and the magnitude of each cell temperature P7 can be compared relatively to estimate the deterioration state of the battery cells Ce in each unit module EM1 to EM8.

[0054] The state estimation unit 33 can also estimate the degradation state of the battery cells Ce in each of the unit modules EM1 to EM8 based on any two or more parameters of the add-on time P1, the number of switching times P2, the internal resistance P3, the output power amount P4, the output / input power difference P5, the integrated current P6, and the cell temperature P7 detected by the parameter detection unit 31. This allows the state estimation unit 33 to accurately estimate the degradation state of the battery cells Ce in each of the unit modules EM1 to EM8 using the two or more parameters.

[0055] Furthermore, in the above description, the state estimation unit 33 relatively compares various parameters in the unit modules EM1 to EM8 and estimates the most severely deteriorated battery cell Ce by relative evaluation, but the state of deterioration of the battery cell Ce may also be estimated by absolute evaluation depending on the parameter, or a combination thereof may be used.

[0056] Based on the estimation information estimated for each unit module EM1 to EM8 by the state estimation unit 33, the control device 4 turns on and off the switching elements SW1, SW2, and controls switching of the connection state of each unit module EM1 to EM8 of the battery pack 1. As a result, the battery pack 1 switches the use of each unit module EM1 to EM8 depending on the degree of deterioration of the battery cell Ce, thereby suppressing deterioration of each battery cell Ce and extending the service life of the entire battery pack 1.

[0057] Furthermore, in such a battery pack 1, when the state estimation unit 33 of the detection device 3 estimates that the deterioration state of the battery cell Ce is below a predetermined threshold, for example, that the performance of the battery cell Ce is 80% of the design value or less, the control device 4 can switch the battery cell Ce in the unit module EM to a detached state, thereby replacing each unit module EM or each battery cell Ce. [Explanation of symbols]

[0058] 1 Battery pack 2 Series circuit 3. Detector 4. Control device 31 Parameter detection unit 33 State estimation unit Ce battery cell EM, EM1 to EM8 unit module P1 Joining time P2 Number of switching P3 Internal resistance P4 Output power P5 Input / output power difference P6 Accumulated current P7 Cell temperature PV parameter value SW switching circuit SW1~SW4 switching elements T1 first terminal T2 second terminal WH Power line WL Power line

Claims

1. A battery pack comprising: a series circuit in which a plurality of unit modules each having a battery cell are connected in series; a detection device that detects a deterioration state of each of the battery cells; and a control device that controls the series circuit, Each of the unit modules includes: a first terminal and a second terminal; a switching circuit that switches a connection state between the battery cell and the first terminal and the second terminal, the connection state including an insertion state in which the battery cell is connected between the first terminal and the second terminal and a removal state in which the first terminal and the second terminal are short-circuited; the detection device includes a parameter detection unit that detects values ​​of one or more parameters related to the state of each of the battery cells, and a state estimation unit that estimates a deterioration state of the battery cells for each of the unit modules based on the values ​​of the parameters detected by the parameter detection unit, The control device controls switching of the connection state by each of the switching circuits based on the inferred information for each unit module inferred by the state inferring section.

2. the parameter detection unit integrates, as the parameter value, the subscription time in the subscription state for each unit module; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the joining time.

3. the parameter detection unit integrates, as the parameter value, the number of times that the switching circuit switches the connection state during a period in which the battery pack is used, for each unit module; 3. The battery pack according to claim 1, wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the number of switching operations.

4. the parameter detection unit detects a voltage of each of the unit modules and a current of each of the unit modules as the parameter values, and calculates an internal resistance of the battery cell for each of the unit modules based on the detected voltage information and current information, respectively; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the internal resistance.

5. the parameter detection unit detects a voltage of each of the unit modules and a current of each of the unit modules as the parameter values, and calculates an output power amount of the battery cell for each of the unit modules based on the detected voltage information and current information, respectively; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the amount of output power.

6. the parameter detection unit detects a voltage of each of the unit modules and a current of each of the unit modules as the parameter values, and calculates an output power amount and an input power amount of the battery cell for each of the unit modules based on the detected voltage information and current information, respectively; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the input power amount and the output power amount.

7. the parameter detection unit detects a current of each of the unit modules as a value of the parameter, and integrates an integrated current flowing through the battery cell for each of the unit modules based on the detected current information; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the integrated current.

8. the parameter detection unit detects a cell temperature, which is the temperature of the battery cell, for each unit module as the parameter value; The battery pack according to claim 1 , wherein the state estimation unit estimates the deterioration state of the battery cells for each unit module based on the cell temperature.

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