Battery control device and battery system

Abstract

The battery control device (combination battery control section 150) has a battery deterioration state estimation section 521, a storage section 180, and an upper limit voltage estimation section 1522. The battery deterioration state estimation section 521 estimates a first deterioration state of the battery based on at least any one of a use history, a capacity maintenance rate, and an internal resistance increase rate of the battery, and estimates a second deterioration state of a structural element inside the battery of each category of the battery. The storage section 180 stores information on an upper limit voltage of the chargeable electric power of each temperature of the battery. The upper limit voltage estimation section estimates the upper limit voltage of the chargeable electric power of the battery based on the information. The upper limit voltage estimation section 1522 updates the information based on the first deterioration state and the second deterioration state.

Description

Technical Field

[0001] This invention relates to a battery control device and a battery system. Background Technology

[0002] The battery systems of electric vehicles (EVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs) generally consist of multiple secondary batteries connected in series or parallel and various electrical components. These electrical components include relays that control the on / off switching of the secondary batteries to the current load, sensors that measure the current or voltage of the secondary batteries, and battery control devices that control the charging and discharging of the secondary batteries.

[0003] To ensure the secondary battery is used within a suitable range, the battery control device sets a voltage limit for the secondary battery and controls its charging and discharging within this limited voltage range. This control prevents overcharging or over-discharging of the secondary battery, thereby suppressing its degradation.

[0004] For example, regarding the control method of the upper limit voltage of a secondary battery, the technology described in Patent Document 1 is known. In Patent Document 1, the moving average of the voltage is calculated according to each average time, and based on the upper limit voltage spectrum composed of the upper limit voltage and temperature determined in advance according to each moving average time, the upper limit voltage is set according to each average time, and the minimum value of the upper limit voltage set according to each average time is set as the upper limit voltage.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent document 1: International Publication No. 2020 / 158182. Summary of the Invention

[0008] The problem the invention aims to solve

[0009] It is desirable to set the upper limit voltage appropriately based on the internal degradation state of the battery.

[0010] means for solving problems

[0011] To address the problems of the prior art, the battery control device of the present invention is characterized by comprising: a battery degradation state estimation unit that estimates a first degradation state of the battery based on at least one of the battery's usage history, capacity retention rate, and internal resistance increase rate, and estimates a second degradation state of structural elements within each type of battery; a storage unit that stores information relating to the upper limit voltage of the rechargeable power of the battery at each temperature; and an upper limit voltage estimation unit that estimates the upper limit voltage of the rechargeable power of the battery based on the information; the upper limit voltage estimation unit updates the information based on the first degradation state and the second degradation state.

[0012] The effects of the invention

[0013] According to the present invention, by variably controlling the upper limit voltage according to the degradation state of the secondary battery, the charging performance of the secondary battery can be safely and maximized. Attached Figure Description

[0014] Figure 1 This is a functional block diagram of the battery system according to the implementation method.

[0015] Figure 2 This is a functional block diagram of the single-battery control unit in the implementation method.

[0016] Figure 3 This is a functional block diagram of the combined battery control unit in the embodiment.

[0017] Figure 4 This is a functional block diagram of the upper limit voltage calculation unit in the implementation method.

[0018] Figure 5 This is a flowchart illustrating the diagnostic process performed by the battery degradation state estimation unit in an embodiment.

[0019] Figure 6 This is a diagram showing the upper limit voltage spectrum of the embodiment and an update of the upper limit voltage spectrum. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. In the following embodiments, the application of the present invention to a battery system constituting a power source for a hybrid electric vehicle will be described. However, the structure of the embodiments described below is not limited thereto, and it can also be applied to the energy storage control circuit, etc., of an energy storage device constituting a power source for a plug-in hybrid electric vehicle, an electric vehicle, or an industrial vehicle such as a hybrid truck.

[0021] Furthermore, the following embodiments are illustrated using lithium-ion batteries as an example, but any rechargeable secondary battery can also be used, such as lead-acid batteries, nickel-metal hydride batteries, and multivalent cation batteries. Further, in the following embodiments, multiple individual cells are connected in series to form a battery pack, but this can also be applied to systems composed of battery packs that are either formed by connecting multiple individual cells connected in parallel in series, or by connecting multiple individual cells connected in series in parallel.

[0022] Figure 1 This is a functional block diagram of the battery system 100 according to the embodiment. The battery system 100 is connected to the inverter 400 via relays 300 and 310. The battery system 100 is configured to include a battery pack 110, a single-cell management unit 120, a current detection unit 130, a voltage detection unit 140, a battery pack control unit 150, and a storage unit 180.

[0023] The battery pack 110 is composed of multiple individual cells 111. The individual cell management unit 120 monitors the status of the individual cells 111. The current detection unit 130 detects the current flowing through the battery system 100. The voltage detection unit 140 detects the total voltage of the battery pack 110. The battery pack control unit 150 detects the status of the battery pack 110 and performs status management, etc.

[0024] The battery pack 110 is constructed by electrically connecting multiple individual cells 111 capable of storing and releasing electrical energy (charging and discharging with direct current) in series. Each individual cell 111 is, for example, a lithium-ion battery with an output voltage of 3.0 to 4.2V (average output voltage: 3.6V). Alternatively, batteries with other voltage specifications may also be used.

[0025] In terms of the management and control of the implementation status, the individual cells 111 constituting the combined battery 110 are grouped into a predetermined number of units. The grouped individual cells 111 are electrically connected in series to form single-cell groups 112a and 112b. The number of individual cells 111 constituting the single-cell group 112 can be the same in all single-cell groups 112, or the number of individual cells 111 in each single-cell group 112 can be different.

[0026] The single-cell management unit 120 monitors the status of the individual cells 111 that constitute the battery pack 110. The single-cell management unit 120 has a single-cell control unit 121 provided for each single-cell group 112. Figure 1 In this configuration, single-cell control units 121a and 121b are respectively provided for single-cell packs 112a and 112b. The single-cell control unit 121 monitors and controls the state of the single cells 111 constituting the single-cell pack 112.

[0027] In this embodiment, for the sake of simplicity, four single cells 111 are electrically connected in series to form single cell groups 112a and 112b. Furthermore, single cell groups 112a and 112b are electrically connected in series to form a combined battery 110 having a total of eight single cells 111.

[0028] The measured values ​​of the battery voltage or temperature of the single battery 111 output from the single battery management unit 120, the current value from the current detection unit 130, the total voltage value of the combined battery 110 output from the voltage detection unit 140, and the battery characteristic information of the single battery 111 stored in the storage unit 180 are input to the combined battery control unit 150.

[0029] In addition, the single-battery management unit 120 has the function of diagnosing whether the single battery 111 is overcharged or over-discharged, and the function of outputting abnormal signals in the event of a communication error in the single-battery management unit 120. These diagnostic results and abnormal signals are also input to the combined battery control unit 150. Furthermore, signals are also input from the higher-level control device, namely the vehicle control unit 200.

[0030] The battery pack control unit 150 performs calculations to appropriately control the charging and discharging of the battery pack 110 based on input information and current limit values ​​and individual battery characteristics pre-stored in the storage unit 180. For example, it performs calculations of charge / discharge limits for each individual battery 111, calculations of the state of charge (SOC) and degradation state (state of health based on resistance, SOHR, and SOHC) for each individual battery 111, and calculations for voltage equalization control of each individual battery 111. The battery pack control unit 150 outputs these calculation results and instructions based on these results to the individual battery management unit 120 and the vehicle control unit 200.

[0031] The storage unit 180 stores information related to battery characteristics of the combined battery 110, individual cells 111, and individual battery pack 112. Furthermore, in this embodiment, the storage unit 180 is configured to be located outside the combined battery control unit 150 or the individual battery management unit 120, but it may also be configured so that the combined battery control unit 150 or the individual battery management unit 120 has a storage unit and stores the aforementioned information therein.

[0032] In addition, the storage unit 180 stores vehicle driving history and vehicle stopping history as information. The vehicle driving history is composed of a graph that combines the current load or electrical load information when charging and discharging the battery pack with the temperature at that time and the time spent in the state of charge (SOC). The vehicle stopping history is composed of a graph that combines the temperature when the vehicle stops and the time spent in the state of charge (SOC).

[0033] The combined battery control unit 150 and the single battery management unit 120 transmit and receive signals via an insulating element 170, typically an optocoupler, and a signal communication unit 160. The insulating element 170 is provided because the combined battery control unit 150 and the single battery management unit 120 operate from different power sources. Specifically, the single battery management unit 120 receives power from the combined battery 110, while the combined battery control unit 150 uses an onboard auxiliary battery (e.g., a 14V battery) as its power source. The insulating element 170 can be mounted on the circuit board constituting the single battery management unit 120 or the circuit board constituting the combined battery control unit 150. Depending on the system architecture, the insulating element 170 can also be omitted.

[0034] The communication method between the combined battery control unit 150 and the individual battery control units 121a and 121b constituting the individual battery management unit 120 will be described. The individual battery control units 121a and 121b are connected in series in descending order of the potential of the individual battery groups 112a and 112b that they monitor.

[0035] The signal sent from the combined battery control unit 150 to the single battery management unit 120 is input to the single battery control unit 121a via the insulating element 170 and the signal communication unit 160. The output of the single battery control unit 121a is input to the single battery control unit 121b via the signal communication unit 160, and the output of the lowest single battery control unit 121b is transmitted to the combined battery control unit 150 via the insulating element 170 and the signal communication unit 160.

[0036] In this embodiment, the single battery control unit 121a and the single battery control unit 121b do not communicate via the insulating element 170, but they can still transmit and receive signals via the insulating element 170.

[0037] The vehicle control unit 200 uses information sent by the combined battery control unit 150 to control the inverter 400, which is connected to the battery system 100 via relays 300 and 310. When the vehicle is in motion, the battery system 100 is connected to the inverter 400 and uses the energy stored in the combined battery 110 to drive the electric generator 410.

[0038] When the vehicle system equipped with battery system 100 is started and in motion, under the management of vehicle control unit 200, battery system 100 is connected to inverter 400, and the energy stored in battery pack 110 is used to drive electric generator 410. During regeneration, the generated electricity from electric generator 410 charges battery pack 110. The energy stored in battery pack 110 through charging is used during the next vehicle trip, or it is also used to operate electrical components inside and outside the vehicle.

[0039] Figure 2 This is a functional block diagram of the single-cell control unit 121 according to the embodiment. The single-cell control unit 121 is configured to include a voltage detection circuit 122, a control circuit 123, a signal input / output circuit 124, and a temperature detection unit 125. The voltage detection circuit 122 measures the voltage between the terminals of each single cell 111. The control circuit 123 receives the measurement results from the voltage detection circuit 122 and the temperature detection unit 125, and sends the measurement results to the combined battery control unit 150 via the signal input / output circuit 124. Furthermore, the circuit structure typically installed in the single-cell control unit 121 to equalize the voltage or SOC deviation between the single cells 111 caused by self-discharge or current consumption deviation is known, and therefore is omitted from description.

[0040] Figure 2 The temperature detection unit 125 of the single-cell control unit 121 has the function of measuring the temperature of the single-cell pack 112. The temperature detection unit 125 measures a temperature for the single-cell pack 112 as a whole, and regards this temperature as a representative temperature value of the single cell 111 constituting the single-cell pack 112. The temperature measured by the temperature detection unit 125 is used for various calculations to detect the state of the single cell 111, the single-cell pack 112, or the combined battery 110. Figure 2 Based on this premise, a temperature detection unit 125 is provided in the single-cell control unit 121. It is also possible to provide a temperature detection unit 125 for each single cell 111 so as to measure the temperature of each single cell 111 and perform various calculations based on the temperature of each single cell 111. However, in this case, the number of temperature detection units 125 increases, and correspondingly, the structure of the single-cell control unit 121 becomes more complex.

[0041] exist Figure 2 The temperature detection unit 125 is shown in a simplified form. In practice, a temperature sensor is installed in the object being measured. This temperature sensor outputs temperature information as a voltage, and the measurement result is sent to the signal input / output circuit 124 via the control circuit 123. The signal input / output circuit 124 then outputs the measurement result to the external device of the single-cell control unit 121. This series of processes is implemented by the temperature detection unit 125 installed in the single-cell control unit 121. The voltage detection circuit 122 can also be used for measuring temperature information (voltage).

[0042] Figure 3 This is a functional block diagram of the combined battery control unit 150 according to the embodiment. The combined battery control unit 150 is the part that performs functions equivalent to a battery control device. The combined battery control unit 150 is the part that determines the state of each individual battery 111 in the combined battery 110 or the power that can be input and output to each individual battery 111 based on the temperature, current value, and voltage value of each individual battery 111 detected during vehicle operation. As one of its functional structural elements, the combined battery control unit 150 has the function of performing calculations on the rechargeable power (charging power limit value) for limiting the charging power of each individual battery 111.

[0043] In addition to the calculation function of rechargeable power, the combined battery control unit 150 also has various functions required for the control of the combined battery 110, such as the function of discharging each individual battery 111 and the function of equalizing the voltage of each individual battery 111. However, these are known functions and are not directly related to the present invention, so detailed descriptions will be omitted below.

[0044] like Figure 3 As shown, the battery pack control unit 150 has functional blocks such as a battery state detection unit 151, an upper limit voltage calculation unit 152, and a rechargeable power calculation unit 153 as its functions. The battery pack control unit 150 uses these functional blocks to calculate the rechargeable power of each individual battery 111 based on the current of the battery pack 110 detected by the current detection unit 130, the voltage of the battery pack 110 detected by the voltage detection unit 140, and the temperature.

[0045] Furthermore, while the calculation of the rechargeable power of the combined battery 110 by the combined battery control unit 150 has been described above, the rechargeable power can also be calculated by aggregating multiple individual batteries 111. For example, it can be calculated for each individual battery pack 112a, 112b, or it can be calculated based on the voltage of each individual battery 111 detected by the individual battery control unit 120. In these cases, the rechargeable power can be calculated using the same process as for the combined battery 110. Additionally, the rechargeable power of each individual battery 111 can be calculated using the same process. Therefore, the object of the rechargeable power calculation will be simply referred to as a "battery" below, and the rechargeable power calculation function in the combined battery control unit 150 will be described.

[0046] The battery state detection unit 151 calculates the battery's SOC, SOHC, and SOHR based on information about the battery's current, voltage, and temperature input to the battery combination control unit 150. Furthermore, the calculation methods for SOC, SOHC, and SOHR are well-known and will not be explained further.

[0047] The upper limit voltage calculation unit 152 takes time-series data of battery voltage and temperature, SOHC, and SOHR as input and calculates the battery voltage history based on these. Then, the upper limit voltage calculation unit 152 calculates and outputs the upper limit voltage of the battery's rechargeable power based on the battery voltage history. Furthermore, the specific calculation method of the upper limit voltage performed by the upper limit voltage calculation unit 152 will be described later.

[0048] The rechargeable power calculation unit 153 calculates and outputs the rechargeable power of the battery based on the battery's SOC, SOHC, and SOHR calculated by the battery state detection unit 151, the battery temperature input to the battery combination control unit 150, and the battery's upper limit voltage calculated by the upper limit voltage calculation unit 152. Here, the rechargeable power is calculated as the product of the rechargeable current that can flow through the battery during charging and the battery voltage when the rechargeable current is applied. The rechargeable current can be calculated as the smaller of the current value that can flow before the battery voltage reaches the upper limit voltage and the current limit value determined by the constituent components (relays, fuses, etc.) of the battery system 100.

[0049] Next, refer to Figures 4-6 This section explains the specific calculation method for the upper limit voltage performed by the upper limit voltage calculation unit 152.

[0050] Figure 4 This is a functional block diagram of the upper limit voltage calculation unit 152 in this embodiment. In this embodiment, the upper limit voltage calculation unit 152 is configured to include a battery degradation state estimation unit 1521 and an upper limit voltage estimation unit 1522.

[0051] The battery degradation state estimation unit 1521 estimates the battery degradation state based on SOHC, SOHR, and the vehicle driving history and vehicle parking history stored in the storage unit 180, and calculates the rate α for updating the upper limit voltage spectrum M. The upper limit voltage spectrum M shows the range of the upper limit voltage of the rechargeable power of each individual cell 111 that can suppress Li deposition. The upper limit voltage spectrum M will be described later.

[0052] The upper limit voltage estimation unit 1522 updates the upper limit voltage spectrum M based on the ratio α of updating the upper limit voltage spectrum M calculated by the battery degradation state estimation unit 1521, which includes information on temperature and upper limit voltage stored in the storage unit 180.

[0053] Specifically, the upper limit voltage estimation unit 1522 updates the upper limit voltage spectrum M by multiplying the threshold V_th by the ratio α calculated by the battery degradation state estimation unit 1521, and updates the upper limit voltage spectrum M with the updated threshold V_th. The threshold V_th determines whether the upper limit voltage V at each temperature T stored in the upper limit voltage spectrum M is an upper limit voltage that can suppress Li deposition in the single cell 111.

[0054] The upper limit voltage estimation unit 1522 estimates the upper limit voltage of the battery corresponding to the temperature by referring to the updated upper limit voltage graph M.

[0055] Figure 5 This is a flowchart illustrating the diagnostic process performed by the battery degradation state estimation unit 1521 according to the embodiment. In step S1, the battery degradation state estimation unit 1521 begins diagnosing the battery degradation state after receiving a signal from the vehicle control unit 200 when the vehicle starts, for example.

[0056] Next, in step S2, the battery degradation state estimation unit 1521 acquires the SOHR and SOHC calculated by the battery state detection unit 151. Alternatively, only the SOHR may be acquired, and the SOHC may be indirectly calculated based on the relationship between SOHR and SOHC. Or, only the SOHC may be acquired, and the SOHR may be indirectly calculated based on the relationship between SOHR and SOHC.

[0057] Next, in step S3, the battery degradation state estimation unit 1521 compares the SOHR and SOHC values ​​obtained by the battery state detection unit 151 with the thresholds SOHR_th and SOHC_th, respectively. Then, if SOHR is higher than the threshold SOHR_th and SOHC is lower than the threshold SOHC_th (step S3 is yes (battery is in a degradation state)), the process proceeds to step S4; otherwise (step S3 is no (battery is not in a degradation state)), the process proceeds to step S7, and the diagnostic process ends.

[0058] Furthermore, in step S3, the battery degradation state estimation unit 1521 is not limited to comparing the values ​​of SOHR and SOHC with the thresholds SOHR_th and SOHC_th; it may only compare SOHC with the threshold SOHC_th. In this case, if SOHC is lower than the threshold SOHC_th (yes in step S3), the battery degradation state estimation unit 1521 will proceed to step S4; otherwise (no in step S3), it will proceed to step S7.

[0059] In addition, in step S3, the battery degradation state estimation unit 1521 can determine the battery degradation state based on the battery usage history (or at least one of vehicle driving history and vehicle parking history) stored in the storage unit 180, SOHR and at least any one of SOHR.

[0060] In step S4, the battery degradation state estimation unit 1521 estimates the internal degradation state of the battery based on the life model of the battery system 100 and the vehicle driving history and vehicle stopping history stored in the storage unit 180, and calculates the positive electrode degradation rate Cp, the negative electrode degradation rate Cn, and the degradation rate Csr caused by side reactions. Then, the battery degradation state estimation unit 1521 transfers the processing to step S5.

[0061] The lifetime model defines the degradation rate of each structural element within the battery. The lifetime model varies depending on the battery type, but for example, in the case of secondary batteries using electrolytes such as Li-ion batteries, the lifetime model defines three degradation indices: positive electrode degradation rate Cp, negative electrode degradation rate Cn, and degradation rate caused by side reactions Csr. The positive electrode degradation rate Cp represents the degradation status of the battery's positive electrode from the point of use (when the battery is new), showing the positive electrode capacity at that degradation rate point. The negative electrode degradation rate Cn represents the degradation status of the battery's negative electrode from the point of use (when the battery is new), showing the negative electrode capacity at that degradation rate point. The degradation rate caused by side reactions Csr represents the deposition of metal ions (lithium in this embodiment) in the electrolyte caused by side reactions of the battery from the point of use (when the battery is new), showing the amount of lithium loss at that degradation rate point. The degradation rate of the positive electrode Cp, the degradation rate of the negative electrode Cn, and the degradation rate Csr caused by side reactions are estimated, for example, based on the battery usage (the proportion of driving time and parking time relative to the total time) inferred from the vehicle's driving history and parking history, using a prescribed calculation method.

[0062] In step S5, the battery degradation state estimation unit 1521 compares each degradation rate calculated in step S4 with the threshold value of each degradation rate. Specifically, if the positive electrode degradation rate Cp is higher than the threshold value Cp_th, and the degradation rate Csr caused by the side reaction is higher than the negative electrode degradation rate Cn (yes in step S5), the battery degradation state estimation unit 1521 transfers the process to step S6; otherwise (no in step S5), the process transfers to step S7 and ends the diagnostic process.

[0063] In step S6, the battery degradation state estimation unit 1521 calculates and updates the ratio α of the upper limit voltage spectrum M according to formula (1) based on the negative electrode degradation rate Cn and the degradation rate Csr caused by the side reaction, and sends the calculated value of ratio α to the upper limit voltage estimation unit 1522. Then, the battery degradation state estimation unit 1521 transfers the processing to step S7 and ends the diagnostic process.

[0064] α = k × (Csr / Cn) (1)

[0065] Where k is a defined constant.

[0066] Figure 6 This is a diagram illustrating the upper limit voltage spectrum M of the embodiment and an updated version of the upper limit voltage spectrum M. Figure 6 In order to simplify the explanation, in the upper limit voltage spectrum M, the horizontal axis is set to the upper limit voltage from V=1 to 5, and the vertical axis is set to the temperature from T=1 to 5. It is represented by a 5th degree matrix of the region R(T,V) (T=1~5, V=1~5) corresponding to the temperature T and the upper limit voltage V. However, the granularity of the horizontal and vertical axes can also be finer. Figure 6 The diagram shows that each region R(T,V) represents any one of the following: "OK", "threshold", and "NG".

[0067] Region R(T, V) marked "OK" indicates that the upper limit voltage V is less than the threshold V_th. This region R(T, V) is the first region of the upper limit voltage that inhibits the deposition of metal ions in the battery electrolyte and allows for charging. Region R(T, V) marked "Threshold" indicates that the upper limit voltage V is equal to the threshold V_th. This is the threshold region of the upper limit voltage that inhibits the deposition of metal ions in the battery electrolyte and allows for charging. Region R(T, V) marked "NG" indicates that the upper limit voltage V exceeds the threshold V_th. This is the second region of the upper limit voltage that causes the deposition of metal ions in the battery electrolyte during charging. The first and second regions divide the upper limit voltage spectrum M in two, with the threshold region as the boundary.

[0068] Hereinafter, the threshold of the upper limit voltage V before the update is set as V_th_1, and the threshold of the upper limit voltage V after the update is set as V_th_2.

[0069] like Figure 6 As shown in the diagram above, the upper limit voltages of regions R(1,1), R(1,2), R(1,3), R(1,4), R(2,1), R(2,2), R(2,3), R(3,1), R(3,2), R(4,1), R(4,2), R(4,3), R(5,1), R(5,2), R(5,3), and R(5,4) are all less than the threshold V_th_1. Therefore, at each temperature T, these upper limit voltages are "OK" and are defined as the first region of the battery's upper limit voltage.

[0070] In addition, such as Figure 6As shown in the figure above, the upper limit voltages of regions R(1,5), R(2,4), R(3,3), R(4,4), and R(5,5) are equal to the threshold voltage V_th_1. Therefore, at each temperature T, these upper limit voltages are the "thresholds," defining the threshold regions for the upper limit voltage of the battery.

[0071] In addition, such as Figure 6 As shown in the figure above, the upper limit voltages of regions R(2,5), R(3,4), R(3,5), and R(4,5) exceed the threshold V_th_1. Therefore, at each temperature T, these upper limit voltages are "NG", defining the second region as the upper limit voltage of the battery.

[0072] Next, the upper limit voltage estimation unit 1522 uses, as shown in the example... Figure 5 The ratio α determined by the diagnostic treatment shown is based on formula (2), which changes the threshold V_th_1 of the upper limit voltage of each temperature T to the threshold V_th_2.

[0073] V_th_2=V_th_1×α (2)

[0074] For example, if α > 1, then V_th_2 > V_th_1. The upper limit voltage estimation unit 1522 re-evaluates each region R(T, V) using the updated threshold V_th_2.

[0075] Therefore, as Figure 6 As shown in the figure below, the upper limit voltages of regions R(1,1), R(1,2), R(1,3), R(1,4), R(2,1), R(2,2), R(2,3), R(2,4), R(3,1), R(3,2), R(3,3), R(4,1), R(4,2), R(4,3), R(4,4), R(5,1), R(5,2), R(5,3), and R(5,4) are all less than the threshold V_th_2. Therefore, at each temperature T, these upper limit voltages are "OK", and the first range of the battery's upper limit voltage is expanded.

[0076] In addition, such as Figure 6 As shown in the figure below, the upper limit voltages of regions R(1,5), R(2,5), R(3,4), R(4,5), and R(5,5) are equal to the threshold voltage V_th_2. Therefore, at each temperature T, these upper limit voltages are the "thresholds," defining the threshold regions for the upper limit voltage of the battery.

[0077] In addition, such as Figure 6As shown in the figure below, the upper limit voltage of region R(3,5) exceeds the threshold V_th_2. Therefore, at temperature T=3, this upper limit voltage is "NG", and the second region of the battery's upper limit voltage is reduced.

[0078] Furthermore, if α < 1, then V_th_2 < V_th_1. If the upper limit voltage of each region R(T, V) is re-evaluated using the updated threshold V_th_2, then the first region is shrunk and the second region is expanded.

[0079] Then, the upper limit voltage estimation unit 1522 estimates the upper limit voltage corresponding to the current battery temperature T based on the first region of the updated upper limit voltage spectrum M, and sets the estimated upper limit voltage in the rechargeable power calculation unit 153.

[0080] In this way, by changing the upper limit voltage threshold V_th, the range of the upper limit voltage of the battery in the upper limit voltage spectrum M can be increased or decreased.

[0081] Furthermore, the upper limit voltage spectrum M described in the above embodiments is an example of information on the range of the upper limit voltage of the battery corresponding to temperature, and is not limited to a spectrum, but may also be a table or function, etc.

[0082] As described above, according to the above embodiment, by variably controlling the upper limit voltage according to the degradation state of the secondary battery, it is possible to control the charging characteristics of the secondary battery safely and to maximize their potential.

[0083] In the above embodiment, the upper limit voltage of the battery's rechargeable capacity is variably controlled according to the battery's internal degradation state to prevent the precipitation of metal ions in the battery electrolyte and to charge a larger amount of energy. The higher the battery's upper limit voltage, the easier it is for metal ions to precipitate; however, the upper limit voltage that prevents metal ion precipitation varies depending on the battery's internal degradation state. By preventing metal ion precipitation and increasing the battery's upper limit voltage according to the battery's internal degradation state, rechargeable capacity can be ensured even as battery degradation progresses, thus suppressing the reduction of the renewable energy capacity of the battery-equipped vehicle and the decrease in fuel consumption rate.

[0084] Furthermore, in the above embodiment, the upper limit voltage of the battery's rechargeable power is variably controlled based on a first degradation state based on at least one of the battery's usage history, capacity retention rate, and internal resistance rise rate, and a second degradation state of the internal structural elements of each type of battery based on a lifespan model (positive electrode degradation rate, negative electrode degradation rate, and degradation rate caused by battery side reactions). The second degradation state is estimated based on the vehicle driving history and vehicle stopping history stored in the storage unit 180. Therefore, by using simple processing of general data such as battery usage history, capacity retention rate, and internal resistance rise rate, the degree of internal battery degradation, such as the precipitation of metal ions in the battery electrolyte, can be estimated.

[0085] Furthermore, in the above embodiment, when at least the capacity retention rate, positive electrode degradation rate, and degradation rate caused by side reactions meet specified conditions, an index value is calculated based on the quotient obtained by dividing the degradation rate caused by side reactions of the battery electrolyte by the negative electrode degradation rate. Then, based on this index value, information related to the upper limit voltage of rechargeable power at each temperature of the battery is updated. Therefore, based on an index that quantitatively grasps the degradation status inside the battery, information related to the upper limit voltage of rechargeable power at each temperature of the battery can be appropriately updated, and a more suitable upper limit voltage can be estimated, thus maximizing the utilization of battery performance throughout the battery's lifespan.

[0086] Furthermore, in the above embodiment, according to each temperature of the battery, the graph representing the first region (the upper limit voltage that can suppress the deposition of metal ions in the battery electrolyte), the threshold region (the threshold of the upper limit voltage that can be suppressed), and the second region (the upper limit voltage that cannot be suppressed) is updated by either expanding the first region and shrinking the second region, or shrinking the first region and expanding the second region. Therefore, since the upper limit voltage corresponding to the current battery temperature can be selected and set from the range determined by the first region and the threshold region, it is possible to consider suppressing the deposition of metal ions in the battery electrolyte and safely maximize the charging performance.

[0087] Furthermore, in the above embodiment, the updated second voltage threshold is calculated by multiplying the voltage threshold before the update by an index value obtained by dividing the degradation rate caused by the side reactions of the battery electrolyte by the degradation rate of the negative electrode. Based on the comparison results between the second voltage threshold and each upper limit voltage, the spectrum of the battery's upper limit voltage is updated. Therefore, with simple processing, the spectrum of the battery's upper limit voltage can be updated according to the battery's degradation state.

[0088] Furthermore, in the above embodiment, the upper limit voltage of the battery is estimated and set based on information related to the upper limit voltage of the rechargeable power at each temperature of the battery, which is updated according to the internal degradation condition of the battery. Therefore, by referring to this information in a simple process, the upper limit voltage of the battery corresponding to the internal degradation condition of the battery can be estimated and set.

[0089] Furthermore, in the above embodiments, in a battery system having a battery control device and a combined battery consisting of multiple batteries, the upper limit voltage of the battery corresponding to the internal degradation of the battery can be estimated and set by referring to information related to the upper limit voltage of the rechargeable power of the battery at each temperature, which is updated according to the internal degradation of the battery.

[0090] The above description is merely an example, and the present invention is not limited to the structures of the above embodiments, but includes various modifications. For example, the above embodiments are detailed descriptions provided for ease of understanding of the present invention and are not necessarily limited to having all the described structures. Furthermore, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and the structure of another embodiment can be added to the structure of one embodiment. Additionally, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced. Furthermore, the order in which the steps in the processing of each embodiment are performed can be appropriately changed as long as the same result is obtained.

[0091] Explanation of reference numerals in the attached figures

[0092] 100: Battery system; 110: Battery pack; 111: Single cell; 112, 112a, 112b: Single battery pack; 120: Single battery management unit; 121: Single battery control unit; 121a, 121b: Single battery control unit; 122: Voltage detection circuit; 123: Control circuit; 124: Signal input / output circuit.

[0093] 125: Temperature detection unit; 130: Current detection unit; 140: Voltage detection unit; 150: Battery combination control unit (battery control device); 151: Battery state detection unit; 152: Upper limit voltage calculation unit; 153: Rechargeable power calculation unit; 180: Storage unit; 1521: Battery degradation state estimation unit.

[0094] 1522: Upper limit voltage estimation section.

Claims

1. A battery control device, characterized in that, have: The battery degradation state estimation unit estimates a first degradation state of the battery based on at least one of the battery's usage history, capacity retention rate, and internal resistance increase rate, and estimates a second degradation state of the internal structural elements of each type of battery. The storage unit stores information related to the upper limit voltage of the rechargeable power of the battery at each temperature, and The upper limit voltage estimation unit estimates the upper limit voltage of the rechargeable power of the battery based on the information. The upper limit voltage estimation unit updates the information based on the first degradation state and the second degradation state. The first degradation state is represented by the capacity retention rate and the internal resistance increase rate. The second degradation state is represented by the degradation rate of the positive electrode, the degradation rate of the negative electrode, and the degradation rate caused by the side reactions of the battery. The battery degradation state estimation unit calculates an index value based on the quotient obtained by dividing the degradation rate caused by the side reaction of the battery electrolyte by the degradation rate of the negative electrode, when at least the capacity retention rate is lower than a threshold, the positive electrode degradation rate is higher than a threshold, and the degradation rate caused by the side reaction is higher than the negative electrode degradation rate. The index value is then sent to the upper limit voltage estimation unit. The upper limit voltage estimation unit updates the information based on the index value.

2. The battery control device according to claim 1, characterized in that, The information is a spectrum, in which, according to each temperature of the battery, the region corresponding to the upper limit voltage below the first voltage threshold is designated as a first region capable of suppressing the deposition of metal ions in the electrolyte of the battery; the region corresponding to the upper limit voltage above the first voltage threshold is designated as a second region unable to suppress the deposition of metal ions; and the region corresponding to the upper limit voltage equal to the first voltage threshold is designated as a threshold region capable of suppressing the deposition of metal ions. The upper limit voltage estimation unit updates the spectrum by either expanding the first region and shrinking the second region, or shrinking the first region and expanding the second region.

3. The battery control device according to claim 2, characterized in that, The upper limit voltage estimation unit calculates the product of the first voltage threshold and an index value based on the quotient obtained by dividing the degradation rate caused by the side reaction of the electrolyte of the battery by the degradation rate of the negative electrode of the battery, and uses this product as the second voltage threshold. In the spectrum, the spectrum is updated in the following manner: according to each temperature of the battery, the region corresponding to the upper limit voltage which is less than the second voltage threshold is set as a new first region capable of suppressing the precipitation of the metal ions, the region corresponding to the upper limit voltage which is greater than the second voltage threshold is set as a new second region that cannot suppress the precipitation of the metal ions, and the region corresponding to the upper limit voltage which is equal to the second voltage threshold is set as a new threshold region capable of suppressing the precipitation of the metal ions.

4. The battery control device according to any one of claims 1 to 3, characterized in that, The upper limit voltage estimation unit estimates and sets the upper limit voltage of the rechargeable power of the battery at each temperature based on the updated information.

5. A battery system, characterized in that, The battery control device having any one of claims 1 to 4, and A combined battery formed by connecting multiple of the aforementioned batteries; The battery control device sets the upper limit voltage of the rechargeable power of the battery at each temperature based on the updated information, thereby controlling the battery and the combined battery.

Images