Secondary battery control system

Abstract

This system provides a secondary battery control system that enables secondary batteries to perform at their full potential by setting power control values ​​that represent more appropriate upper and lower limits for usable power. [Solution] The secondary battery control system includes a first acquisition unit that acquires a power limit value that limits the power that can be input and output during charging and discharging of the secondary battery; a second acquisition unit that acquires a measured voltage value indicating the voltage when power input and output exceeding a predetermined value is performed during charging and discharging of the secondary battery; and a correction unit that corrects the power limit value based on the measured voltage value.

Description

Technical Field

[0001] The present invention relates to a secondary battery control system.

Background Art

[0002] Conventionally, if a rechargeable secondary battery is used beyond the usable upper and lower voltage limits, for example, excessive heat generation may occur, accelerating the deterioration of the secondary battery, or the safety device may function and temporarily disable use (charging and discharging). Therefore, techniques have been proposed to estimate in advance the input / output available power using the difference between the measured terminal voltage and the upper and lower voltage limits, the estimated value of the internal resistance, etc., and perform the input / output of the secondary battery within that range.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is difficult to estimate the internal resistance of a secondary battery, and sufficient estimation accuracy may not be obtained. Also, when estimating the input / output available power in advance based on the estimation of the internal resistance of the secondary battery, there is a tendency to make a conservative estimation. Therefore, there is a problem that the input / output available power is restricted more than necessary, and the original performance of the secondary battery may not be exhibited.

[0005] An object of the present invention is to provide a secondary battery control system capable of setting a power control value, which is a more appropriate usable upper and lower limit value, and exhibiting the original performance of the secondary battery.

Means for Solving the Problems

[0006] To achieve the above objective, the secondary battery control system according to the present invention comprises: a first acquisition unit that acquires a power limit value that limits the power that can be input and output during charging and discharging of a secondary battery; a second acquisition unit that acquires a measured voltage value indicating the voltage when power input and output exceeding a predetermined value is performed during charging and discharging of the secondary battery; and a correction unit that corrects the power limit value based on the measured voltage value.

[0007] With this configuration, for example, the power limit that restricts the input and output power is corrected based on the actual measured voltage value when power exceeding a predetermined value is input or output. As a result, feedback control based on the actual state (response) of the secondary battery optimizes the charging and discharging (input and output) of the secondary battery, making it easier for the secondary battery to perform at its full potential.

[0008] Furthermore, the secondary battery control system according to the present invention may include, for example, a third acquisition unit that acquires a target value for the measured voltage that can take when power input and output exceeding a predetermined value is performed during charging and discharging, and the correction unit may correct the power limit value so that the measured voltage converges to a predetermined range including the learned target value.

[0009] With this configuration, for example, the power limit value can be corrected so that the measured voltage value converges to a predetermined range (or the learning target value) that includes the learning target value when power input and output exceeding a predetermined value is performed. As a result, it becomes possible to correct the power limit value of the secondary battery to a targeted range that takes into account the performance and safety of the secondary battery, making it easier to fully utilize the performance of the secondary battery.

[0010] Furthermore, the secondary battery control system according to the present invention may include, for example, a fourth acquisition unit that acquires learning regions for the secondary battery that are divided according to the charge state and temperature of the secondary battery, and the correction unit may correct the power limit value for each learning region based on the current charge state and temperature of the secondary battery.

[0011] This configuration allows for adjustment of power limits for each learning region, which is divided by factors such as the charge state and temperature of the secondary battery. As a result, the performance of the secondary battery can be controlled in more detail, enabling it to perform at its full potential. [Effects of the Invention]

[0012] According to the present invention, it becomes possible to set power control values ​​that are more appropriate upper and lower limits for usability, and a secondary battery control system is provided that can bring out the full potential of the secondary battery. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is an exemplary and schematic block diagram showing the configuration of a secondary battery control system according to an embodiment. [Figure 2] Figure 2 is an illustrative and schematic diagram illustrating the power change, differential power change, timing for satisfying the learning execution conditions, and voltage change during the discharge of a secondary battery in a secondary battery control system according to an embodiment. [Figure 3] Figure 3 is an illustrative and schematic diagram showing the learning area (map) used when correcting the power limit value in the secondary battery control system according to the embodiment. [Figure 4] Figure 4 is an illustrative and schematic diagram showing the amount of learning update during correction learning in the secondary battery control system according to the embodiment. [Figure 5] Figure 5 is an exemplary flowchart showing the control flow in the secondary battery control system according to the embodiment. [Modes for carrying out the invention]

[0014] Embodiments of the secondary battery control system according to the present invention will be described in detail below with reference to Figures 1 to 5. However, the present invention is not limited to the following embodiments, and the components in the following embodiments include those easily conceivable by those skilled in the art, those substantially identical, and those within the so-called equivalent range. Furthermore, various omissions, substitutions, modifications, and combinations of components can be made without departing from the spirit of the following embodiments.

[0015] Figure 1 is an illustrative and schematic block diagram showing the configuration of the secondary battery control system 10 according to this embodiment. In this embodiment, as an example, the case in which the secondary battery control system 10 is installed and applied to an electric vehicle will be described.

[0016] The secondary battery control system 10 is also referred to as a BMS (battery management system) 12. The BMS 12 suppresses performance degradation due to overcharging or over-discharging of the secondary battery 14 during charging and discharging by limiting the power that can be input and output to the rechargeable secondary battery 14. The BMS 12 may also have functions to manage the temperature of the secondary battery 14 to prevent excessive heat generation and to calculate the remaining capacity of the secondary battery 14 and equalize the cell voltage. In Figure 1, the characteristic functions of this embodiment are mainly explained, including the processing including correction learning of the power limit value that limits the power that can be input and output to the secondary battery 14 during charging and discharging, and the management of the secondary battery 14, and other functions are not illustrated or explained.

[0017] The BMS12 is connected to the secondary battery 14 and manages the input and output of the secondary battery 14. The BMS12 may be provided separately from the secondary battery 14, as shown in Figure 1, or it may be provided integrally with the secondary battery 14.

[0018] The secondary battery 14 is mounted on, for example, an electric vehicle and can supply (discharge) power to a motor / generator (hereinafter referred to as MG) 18 via an inverter 16. Also, when the MG 18 is regeneratively driven, the power generated by regeneration can be supplied (charged) to the secondary battery 14. Note that the secondary battery 14 may also be charged by being connected to another power source such as a commercial power supply. The secondary battery 14 may be composed of a battery pack in which a plurality of cell batteries are connected in series and in parallel. In the present embodiment, the secondary battery 14 is regarded as one battery, and correction learning of a power limit value described below is performed so that optimal charge and discharge can be achieved in the secondary battery 14.

[0019] The inverter 16 converts direct current (DC) supplied from the secondary battery 14 into alternating current (AC). Note that the inverter 16 includes a converter circuit that converts AC into DC and a capacitor. Therefore, the power when the MG 18 is regeneratively driven can be supplied (charged) to the secondary battery 14.

[0020] The MG 18 is, for example, a three-phase AC motor and is driven by the power stored in the secondary battery 14. That is, the DC power output from the secondary battery 14 is boosted by a converter (not shown), and this boosted DC power is converted into AC power by the inverter 16 and supplied to the MG 18. When the MG 18 is mounted as a drive source of an electric vehicle, the driving force of the MG 18 is transmitted to the wheels via a speed reducer (not shown) to run the electric vehicle. Also, when the electric vehicle decelerates, etc., the MG 18 is rotated by the wheels and regenerative operation can be executed. In this case, the MG 18 functions as a generator, and the AC regeneratively generated by the MG 18 is converted into DC by the converter function included in the inverter 16 and charged to the secondary battery 14. Note that the MG 18 may be incorporated into the wheel as an in-wheel motor. Also, the MG 18 may be mounted on a hybrid vehicle that is used together with an internal combustion engine as a drive source or in which the internal combustion engine and the MG 18 are selectively used.

[0021] The vehicle ECU (Electronic Control Unit) 20 is connected to the BMS 12 and the inverter 16 and controls the MG 18. In addition to controlling the MG 18, the vehicle ECU 20 can perform various controls for driving (using) the electric vehicle, but its configuration and description are omitted.

[0022] The BMS 12 includes an acquisition unit 22, a correction unit 24, a control unit 26, a storage unit 28, etc. The acquisition unit 22, the correction unit 24, the control unit 26, etc. may be modules realized by the CPU (Central Processing Unit) included in the BMS 12 reading a control program installed and stored in, for example, a ROM (Read Only Memory) or an SSD (Solid State Drive, flash memory), etc., and according to the control program. Also, all or part of the acquisition unit 22, the correction unit 24, the control unit 26, etc. may be configured by hardware.

[0023] The acquisition unit 22 includes individual acquisition modules that acquire basic information such as the current state of charge (SOC: State Of Charge) of the secondary battery 14 and the current temperature of the secondary battery 14, and also acquire various information used to correct the power limit value for charging and discharging the secondary battery 14 in an optimal state. That is, the acquisition unit 22 includes, as acquisition modules, for example, a first acquisition unit 22a, a second acquisition unit 22b, a third acquisition unit 22c, a fourth acquisition unit 22d, etc. that are functionally divided. In another embodiment, the first acquisition unit 22a, the second acquisition unit 22b, the third acquisition unit 22c, the fourth acquisition unit 22d, etc. may be configured by integrating two or more functions.

[0024] The correction unit 24 performs correction processing and learning processing on the power limit value for charging and discharging the secondary battery 14 in an optimal state. Note that the details of the correction learning in the correction unit 24 will be described later. The control unit 26 manages the corrected power limit value and controls the charging and discharging of the secondary battery 14. The storage unit 28 stores the reference power limit value, the corrected power limit value, etc. Also, the storage unit 28 can store various parameters used to charge and discharge the secondary battery 14 and various programs used in the BMS 12.

[0025] Figure 2 is an illustrative and schematic diagram illustrating the power changes, differential power changes, timing of satisfying the learning execution conditions, and voltage changes during control (e.g., discharge) of the secondary battery 14 in the secondary battery control system 10 (BMS12). Note that in this embodiment, the control in the secondary battery control system 10 (BMS12) shows the output and input states of power and voltage in reverse during discharge and charging of the secondary battery 14, but the phenomena are substantially the same. Therefore, when illustrating phenomena in Figure 2 and the following description, the description will refer to the state when the secondary battery 14 is discharging.

[0026] The first acquisition unit 22a, included in the acquisition unit 22, acquires a power limit value that limits the input / output power during charging and discharging of the secondary battery 14. Based on the current state of the secondary battery 14, the first acquisition unit 22a acquires a power limit value that will serve as the standard for the current processing cycle. For example, consider the case where the secondary battery 14 is discharged as shown in Figure 2, where power W is represented. When the correction learning of this embodiment is performed for the first time on a new secondary battery 14 (a secondary battery 14 in a state without degradation, etc.), a power limit value Wout1 that limits power W is set. The power limit value Wout1 is, for example, a value stored in the storage unit 28. The power limit value Wout1 used for the first time in the correction learning of this embodiment can be a fixed value determined in advance by testing, etc.

[0027] In this embodiment, the power limit value is appropriately modified by the correction unit 24 based on the input and output voltages of the secondary battery 14 during charging and discharging, and by learning this modification, the power limit value is optimized each time the secondary battery 14 is charged or discharged. In addition, the contents of the memory unit 28 are updated with the modified power limit value. For example, as a result of correction learning, the power limit value Wout1 is corrected to, for example, the power limit value Wout2 shown by the dashed line in Figure 2. Furthermore, the corrected power limit value Wout2 can be further modified depending on the state of the secondary battery 14. In this way, the correction unit 24 makes it possible to continuously achieve optimal charging and discharging for each secondary battery 14 (charging and discharging in a state in which the capacity of the secondary battery 14 is fully utilized) by appropriately updating (correcting) the power limit value.

[0028] The second acquisition unit 22b acquires a measured voltage value V11 that indicates the voltage V1 when power W is input or output at a predetermined value (for example, the learning execution condition power Wt in Figure 2) or higher during charging and discharging of the secondary battery 14 (for example, the voltage when the power W during discharge is equal to or higher than the learning execution condition power Wt). In this case, the power W of the secondary battery 14 is limited by the power limit value (for example, power limit value Wout1) acquired by the first acquisition unit 22a. Therefore, the output voltage V1 is also limited. Here, the measured voltage value V11 is a value that can be used to determine whether or not to perform correction learning of the power limit value. Therefore, when the power W output from the secondary battery 14 becomes equal to or higher than the predetermined value (equal to or higher than the learning execution condition power Wt), the correction unit 24 can execute the power limit value correction learning process based on the measured voltage value V11. The power equal to or higher than the predetermined value (learning execution condition power Wt) can be set to a value such as 0.9 times the current power limit value (selectable as appropriate). In other words, the learning execution condition power Wt is set so that when the secondary battery 14 is charged or discharged (discharged in the case of Figure 2), a power value as close as possible to the power limit (power limit Wout1) is obtained, without exceeding the current power limit. As a result, it becomes easier to identify the power W at which power W is greater than or equal to the learning execution condition power Wt and is output within the range that does not exceed the power limit, and the second acquisition unit 22b can more easily obtain the highest value among the measured voltage values ​​V11 corresponding to the power W during discharge near the current power limit.

[0029] Furthermore, when the second acquisition unit 22b acquires a measured voltage value, it is desirable that the charge / discharge state of the secondary battery 14 in the preceding stage is stable. If the charge / discharge state of the secondary battery 14 in the preceding stage is not stable (for example, if the internal resistance state of the secondary battery 14 is not stable), the measured voltage value V11 to be acquired may also be unstable. As a result, there is a risk that incorrect learning may occur in the correction learning of the power limit value. Therefore, as shown in Figure 2, when the power ΔW (Δ power) that fluctuates during the charge / discharge of the secondary battery 14 (for example, during discharge) is within a predetermined range L1 (when the output state of the secondary battery 14 can be considered stable), the correction unit 24 determines that one of the learning execution conditions (conditions under which the power limit value can be corrected) has been met. The second acquisition unit 22b then acquires the maximum voltage as the measured voltage value V11 when the power W exceeds the learning execution condition power Wt and is less than or equal to the power limit value at that time (for example, power limit value Wout1). When the fluctuation of power W output from the secondary battery 14 (power ΔW) is stable within a predetermined range L1, it becomes possible to detect significant power fluctuations (rising point of change in power ΔW), making it easier to determine a learning interval T that satisfies the learning execution conditions. As a result, the second acquisition unit 22b can acquire accurate measured voltage values, and the correction unit 24 can perform appropriate learning correction processing. When the secondary battery 14 is installed in an electric vehicle, the state in which power ΔW (Δ power) falls within the predetermined range L1 is, for example, when the electric vehicle is stopped or driving at a constant speed. Furthermore, the state in which power W exceeds the learning execution condition power Wt and is less than or equal to the power limit value at that time (for example, power limit value Wout1) is when the electric vehicle is accelerating. In other words, in the secondary battery control system 10 (BMS12) of this embodiment, power limit value correction learning is performed when the electric vehicle is accelerating. Therefore, power limit value correction learning during charging of the secondary battery 14 is performed when the electric vehicle is decelerating.

[0030] The third acquisition unit 22c acquires a target value V2 for the measured voltage when power input / output exceeds a predetermined value during charging and discharging. The learned target value V2 is the target value for converging the voltage (measured voltage value V11) when power input / output exceeds a predetermined value during charging and discharging of the secondary battery 14. In the third acquisition unit 22c, the learned target value V2 may be a value that has been determined (calculated) in advance, or it may be determined (calculated) and acquired in the third acquisition unit 22c. When determining the learned target value V2, first, the lower limit voltage V0 of the secondary battery 14 shown in Figure 2 is acquired (calculated). The lower limit voltage V0 is the voltage that is expected to be reached when power is used up to the power limit value (input / output lower limit guard value) during the design stage of the secondary battery 14, and can be acquired (calculated) from, for example, the open circuit voltage, the power limit value at the initial setting, the internal resistance, etc. Next, the expected voltage value Vs is acquired (calculated). The expected voltage Vs is the voltage expected to be reached when using the power of the learned execution condition power Wt during charging and discharging. The expected voltage Vs can be calculated, for example, from the open-circuit voltage, the power limit value at the initial setting, the internal resistance at the initial setting, etc., similar to the lower limit voltage V0. The expected voltage Vs can be obtained (calculated) for example, (open-circuit voltage - lower limit voltage) × (ratio of the learned execution condition power Wt to ​​the power limit value Wout1: e.g., 0.9). The learning target value V2 can then be obtained (calculated) as the expected voltage Vs plus a voltage that takes a safety factor into consideration. The safety factor may be a fixed value, for example, 0.1V (selectable as appropriate), or it may be selected as appropriate based on the state of the secondary battery 14, etc. For example, if the temperature of the secondary battery 14 is low, the safety factor may be estimated to be higher.

[0031] The correction unit 24 can set a predetermined learning dead zone L2 centered on the learning target value V2 acquired by the third acquisition unit 22c. The learning dead zone L2 defines the range in which the measured voltage value V11 will not converge to the learning target value V2. As mentioned above, the learning target value V2 is the target value for convergence of the voltage (measured voltage value V11) when power input and output exceeding a predetermined value is performed during charging and discharging of the secondary battery 14. Therefore, if correction learning of the power limit value is performed when the measured voltage value V11 is sufficiently close to the learning target value V2, the power limit value, which is already an appropriate value, may be overcorrected, and the power limit value may diverge. In other words, if the learning dead zone L2 is not set or if the learning dead zone L2 is too small, there is a risk of incorrect learning of the power limit value. Conversely, if the setting of the learning dead zone L2 is too large, it may become difficult to perform correction learning of the power limit value. Therefore, it is desirable to set an appropriate value for the learning dead zone L2 in advance through testing or other means. The learning dead zone L2 may also be changed depending on the state of the secondary battery 14 (e.g., temperature).

[0032] The fourth acquisition unit 22d acquires learning regions for the secondary battery 14, which are divided by the state of charge (SOC) and temperature of the secondary battery 14. In the correction unit 24, the correction of the power limit value of the secondary battery 14 described above is corrected and learned for each learning region based on the current SOC and temperature of the secondary battery 14. For example, the internal resistance of the secondary battery 14 changes significantly depending on the temperature and SOC during use. Therefore, the correction unit 24 can perform detailed correction of the power limit value according to the current state of the secondary battery 14 by performing correction learning for each region divided by the temperature and SOC of the secondary battery 14 during use.

[0033] Figure 3 is an illustrative and schematic diagram showing the learning area M used when correcting the power limit value in the secondary battery control system 10 (BMS 12). The learning area M can be stored in the memory unit 28 as map information, for example. The learning area M has temperature on the vertical axis and SOC on the horizontal axis, and is divided into multiple individual areas (for example, areas A to I), and the size of each area and the number of divisions can be determined in advance by testing, etc. When the power limit value is corrected in the correction unit 24, the corrected power limit value is stored in the corresponding division, and in the next correction learning processing cycle (processing timing), the first acquisition unit 22a can acquire the reference power limit value based on temperature and SOC. In addition, areas A to I of the learning area M corresponding to a new secondary battery 14 store power control values ​​determined in advance by testing, etc., and the contents of areas A to I can be updated each time correction learning is performed.

[0034] Incidentally, in Figure 2, a correction learning exclusion region Z is provided around regions A to I. This region represents a state of the secondary battery 14 where at least one of the temperature or state of charge (SOC) is close to the limit value, for example, a region where the temperature of the secondary battery 14 is too high or too low, or a region where the SOC is too high or too low, or a combination of these. The internal resistance in such regions may become unstable, and as a result, the state of the secondary battery 14 may also become unstable. In other words, performing correction learning of the power limit value in the aforementioned limit regions increases the likelihood of mislearning. Therefore, regions where mislearning is possible are excluded in advance as the correction learning exclusion region Z. The power limit value in the correction learning exclusion region Z is set to a fixed value with a sufficiently high safety factor, determined in advance through testing, etc., and is used to control the power during charging and discharging of the secondary battery 14.

[0035] In this embodiment, the correction unit 24 acquires (calculates) the above-mentioned lower limit voltage V0, estimated voltage Vs, learning target value V2, etc. for regions A to I selected based on the current state of the secondary battery 14, and corrects the power limit value for each region A to I. Note that the learning target value V2 may be set uniformly for all regions.

[0036] As described above, the correction unit 24 corrects the power limit value based on the measured voltage value V11 acquired by the second acquisition unit 22b. First, the correction unit 24 determines whether the measured voltage value V11, which represents the voltage when power W of a predetermined value (for example, the learning execution condition power Wt in Figure 2) or more is input / output during charging and discharging of the secondary battery 14 (for example, the voltage when it is equal to or greater than the learning execution condition power Wt), is included in the learning dead zone L2. Then, as shown in Figure 2, if the measured voltage value V11 is not included in the learning dead zone L2, the correction unit 24 corrects the power limit value so that the measured voltage value V11 converges to a predetermined range including the learning target value V2. For example, as shown in Figure 2, if the measured voltage value V11 during discharge is smaller than the learning target value V2, the correction unit 24 increases the power limit value so that the measured voltage value V11 converges to a predetermined range including the learning target value V2, for example, the measured voltage value V12.

[0037] In this case, the correction unit 24 determines the amount of correction (learning update amount) for the power limit value for each region (region A to region I) shown in Figure 3, according to the difference between the learning target value V2 and the voltage during learning, i.e., the acquired measured voltage value V11. Figure 4 is an illustrative and schematic explanatory diagram showing the learning update amount (magnitude of correction) during correction learning in the secondary battery control system 10. As shown in Figure 4, the learning update amount is set to be larger the further the measured voltage value V11 is from the learning target value V2 (learning dead zone) (the larger the difference between the measured voltage value V11 and the learning target value V2). In other words, the larger the difference, the more efficiently the value is set to converge to the learning target value V2. Note that the learning update amount may also be changed according to the current temperature of the secondary battery 14. That is, the lower the temperature of the secondary battery 14, the smaller the learning change amount may be. In this way, by setting the learning update amount according to the state of the secondary battery 14, the occurrence of erroneous learning can be suppressed.

[0038] Furthermore, attempting to drastically reduce the difference between the measured voltage value V11 and the learning target value V2 during learning increases the likelihood of erroneous learning. For example, there is a possibility of accidentally using an inappropriate value during learning. Therefore, the correction unit 24 performs correction learning in stages. In other words, the learning update amount is set so that correction learning is performed in small increments. With this setting, when correcting the power limit value, the measured voltage value V11 can be gradually (slowly) converged to the learning target value V2. For example, in the first learning cycle (power limit value correction cycle), the learning update amount is set to X% (e.g., 5%) of the current power limit value and added to the current power limit value. Due to this +X% correction, in the second learning cycle, the measured voltage value V11 is likely to approach the learning target value V2, and the difference between the measured voltage value V11 and the learning target value V2 is likely to be small. Therefore, in the second learning cycle, the learning update amount is set to Y% (X>Y: e.g., 2%) of the current power limit value (the value after +X%) and added to the power limit value. This +Y% correction makes it possible to bring the acquired measured voltage value V11 (a voltage value that does not reach the learning dead zone L2) even closer to the learning target value V2. Similarly, the correction unit 24 repeats the correction learning of the power limit value while reducing the amount of learning update each time correction learning is performed (each time the voltage difference becomes smaller). When the measured voltage value V11 comes into the learning dead zone L2 due to this correction of the power limit value (measured voltage value V12), that is, when it approaches the learning target value V2 sufficiently, the correction unit 24 terminates the correction learning.

[0039] However, as a result of correcting the power limit value, the measured voltage value V13 shown in Figure 2 may exceed the learning dead zone L2 on the opposite side. In such cases, the correction unit 24 subtracts P% (for example, 3%) of the current power limit value as the learning update amount so that the measured voltage value converges to the learning target value V2.

[0040] The control unit 26 provides a battery control signal to the vehicle ECU to control the charging and discharging of the secondary battery 14 based on the corrected and learned power limit value. The control unit 26 also continuously monitors and manages the state of the secondary battery 14.

[0041] The memory unit 28 is a rewritable, non-volatile memory unit that continues to store data (such as corrected and learned power limit values) even when the power supply of the secondary battery control system 10 (BNS12) is turned off (including when the ignition switch of an electric vehicle is turned off). The memory unit 28 can be configured as, for example, flash memory. In addition to the reference power limit value used during initial learning, the memory unit 28 stores learning areas M (maps) in which corrected and learned power limit values ​​are stored for each area A to I shown in Figure 3. When the power supply of the secondary battery control system 10 (BMS12) is turned on again after being turned off once, and the secondary battery 14 is charged and discharged for the next time, the already corrected and learned power limit value that serves as the reference for corrected learning is read out and referenced by the first acquisition unit 22a. In other words, even if the performance of the secondary battery 14 may have changed due to aging or other reasons, a power limit value appropriate to that state is referenced from the beginning, and charge and discharge control is performed, and further corrected learning can be continuously and smoothly performed for the current state of the secondary battery 14. Furthermore, the corrected and learned power limit values ​​stored in the memory unit 28 can be reset. In this case, it becomes possible to perform new correction learning based on the state of the secondary battery 14, for which the performance may have changed due to aging or other factors.

[0042] The procedure for correction learning processing by the secondary battery control system 10 (BMA12) configured in this way will be explained using the flowchart in Figure 5.

[0043] When the secondary battery control system 10 (BMS12) is started (for example, when the ignition switch of an electric vehicle is turned on), the acquisition unit 22 acquires the state of charge (SOC) and the temperature of the secondary battery 14, which indicate the current state of the secondary battery 14 (S100).

[0044] Next, the correction unit 24 performs a learning area determination (S102). That is, the fourth acquisition unit 22d of the acquisition unit 22 acquires the learning area M (areas A to I, or the correction learning exclusion area Z) to which the current state of the secondary battery 14 belongs, based on the acquired SOC and temperature.

[0045] Next, the correction unit 24 determines whether the learning execution conditions for performing a power limit correction learning process for the secondary battery 14 in its current state are met (S104). If the correction unit 24 determines that the current state of the secondary battery 14 belongs to the correction learning exclusion region Z, it considers that the possibility of erroneous learning is high, as described above, and determines that the learning execution conditions are not met (No in S104), and terminates this flow for the time being. In other words, no power limit correction learning is performed, the current power limit is maintained, and the control unit 26 performs charge and discharge control of the secondary battery 14 with the uncorrected power limit.

[0046] Furthermore, if the correction unit 24 determines that the current state of the secondary battery 14 belongs to any of the regions A to I, the third acquisition unit 22c acquires the learning target value V2 as described above. The correction unit 24 also sets a predetermined learning dead zone L2 around the learning target value V2.

[0047] Next, the correction unit 24 determines whether the second acquisition unit 22b can acquire the measured voltage value, that is, whether the power ΔW (power fluctuation) of the secondary battery 14 during charging and discharging (for example, during discharging) is within a predetermined range L1, as another learning execution condition determination. If the power ΔW (power fluctuation) is not within the predetermined range L1, the measured voltage value may become unstable, and in this case, it is determined that the learning execution condition is not met (No. in S104), and this flow is terminated. In other words, no correction learning of the power limit value is performed, the current power limit value is maintained, and the control unit 26 performs charging and discharging control of the secondary battery 14 with the uncorrected power limit value.

[0048] If the power ΔW (power fluctuation) of the secondary battery 14 during charging and discharging (for example, during discharging) is within a predetermined range L1, it is determined that the learning execution condition (condition for correcting the power limit value) is met (Yes in S104), and the process proceeds to S106. In this case, the second acquisition unit 22b acquires the maximum voltage as the measured voltage value V11 in the learning interval T where the power W output by the secondary battery 14 exceeds the learning execution condition power Wt and is less than or equal to the power limit value at that time (for example, power limit value Wout1).

[0049] The correction unit 24 then performs a learning determination (S106). First, the correction unit 24 determines whether the measured voltage value V11 acquired by the second acquisition unit 22b is included in the learning dead zone L2. As shown in Figure 2, if the measured voltage value V11 is included in the learning dead zone L2, the correction unit 24 determines that the measured voltage value V11 has already converged to the learning target value V2, and that correction of the power limit value is unnecessary in the current state of the secondary battery 14 (No. in S106), and terminates this flow for the time being. In other words, no correction learning of the power limit value is performed, the current power limit value is maintained, and the control unit 26 performs charge and discharge control of the secondary battery 14 with the uncorrected power limit value.

[0050] On the other hand, as shown in Figure 2, if the measured voltage value V11 is not included in the learning dead zone L2, it is determined that it is necessary to converge the measured voltage value V11 to a predetermined range including the learning target value V2 (Yes in S106). That is, the correction unit 24 performs a correction of the power limit value and updates the learning value (S108). For example, as shown in Figure 2, if the measured voltage value V11 is smaller than the learning target value V2 during discharge, a correction is performed to increase the power limit value so that the measured voltage value V11 converges to a predetermined range including the learning target value V2, for example, to a measured voltage value V12. In this case, as described above, the correction unit 24 performs the correction learning in stages. That is, the amount of learning update is set in small increments, and the power limit value is corrected to gradually converge the measured voltage value V11 to the learning target value V2.

[0051] The control unit 26 calculates a power limit value (power guard value) that reflects the results of the correction learning, stores it in the corresponding area (area A to area I) of the learning area M (map) stored in the memory unit 28 (S110), and then terminates this flow. In other words, the control unit 26 performs charge and discharge control of the secondary battery 14 based on the corrected and learned power limit value.

[0052] (Effects of this embodiment) As described above, the secondary battery control system 10 (BMS12) according to this embodiment includes a first acquisition unit 22a that acquires a power limit value that limits the power that can be input and output during charging and discharging of the secondary battery 14, a second acquisition unit 22b that acquires measured voltage values ​​(V11, V12, V13) that indicate the voltage when power input and output exceeding a predetermined value is performed during charging and discharging of the secondary battery 14, and a correction unit 24 that corrects the power limit value based on the measured voltage values ​​(V11, V12, V13). With this configuration, for example, the power limit value that limits the input and output power is corrected based on the actual measured voltage values ​​(V11, V12, V13) when power input and output exceeding a predetermined value is performed. As a result, by feedback control based on the actual state (response) of the secondary battery 14, the charging and discharging (input and output) of the secondary battery 14 can be optimized, making it easier for the secondary battery 14 to exhibit its original performance.

[0053] Furthermore, the secondary battery control system 10 (BMS12) according to the present invention includes a third acquisition unit 22c that acquires a target value V2 for the measured voltage values ​​(V11, V12, V13) when power input / output exceeds a predetermined value during charging and discharging. The correction unit 24 may correct the power limit value so that the measured voltage values ​​(V11, V12, V13) converge to a predetermined range including the learning target value V2. With this configuration, for example, the power limit value can be corrected so that the measured voltage values ​​(V11, V12, V13) when power input / output exceeds a predetermined value converge to a predetermined range including the learning target value V2 (or the learning target value V2). As a result, it becomes possible to correct the power limit value of the secondary battery 14 to a targeted range that takes into account the performance and safety of the secondary battery, making it easier to fully utilize the performance of the secondary battery 14.

[0054] Furthermore, the secondary battery control system 10 (BMS12) according to the present invention includes a fourth acquisition unit 22d that acquires a learning region M (regions A to I) for a secondary battery 14, which is divided by the charge state (SOC) and temperature of the secondary battery 14. The correction unit 24 may correct the power limit value for each learning region M (regions A to I) based on the current SOC and temperature of the secondary battery 14. With this configuration, for example, it becomes possible to correct the power limit value for each learning region M (regions A to I) which is divided by the SOC and temperature of the secondary battery 14. As a result, the performance of the secondary battery 14 can be controlled in more detail, and the performance of the secondary battery 14 can be fully utilized.

[0055] As described above, the secondary battery control system 10 (BMS12) of this embodiment makes it possible to set appropriate power limits, thereby making it easier for the secondary battery 14 to perform to its full potential. As a result, when the secondary battery control system 10 (BMS12) is applied to, for example, an electric vehicle, it is possible to easily improve the acceleration performance of the electric vehicle, improve energy efficiency (fuel consumption) in the case of a hybrid vehicle, and extend the lifespan of the secondary battery 14. Furthermore, by setting appropriate power limits using the secondary battery control system 10 (BMS12), it is also possible to contribute to improving the safety of the secondary battery.

[0056] The target of the secondary battery control system 10 (BMS12) of this embodiment can be appropriately changed as long as it is a system that utilizes a secondary battery 14. The secondary battery control system 10 (BMS12) can be applied to other types of vehicles such as railway vehicles, aircraft, ships, etc. that are equipped with a secondary battery 14, and the same effects as in this embodiment can be obtained. Furthermore, the secondary battery control system 10 (BMS12) of this embodiment can be applied to equipment and electronic devices that utilize a secondary battery 14, and the same effects as in this embodiment can be obtained.

[0057] Furthermore, the above-described embodiment showed a case where the secondary battery 14 is composed of a group of batteries connected in series and parallel. Then, an example was shown in which the entire group of batteries is considered as a single secondary battery 14 and corrected learning of the power limit value is performed to enable optimal charging and discharging.In other embodiments, first, corrected learning of the power limit value is performed for each of the batteries connected in series and parallel.Then, the most stringent power limit value among the power limit values ​​corrected and learned for each battery may be selected and used as the power limit value for the entire secondary battery 14.In this case, corrected learning of the power limit value can be performed with improved reliability, taking into account the performance and safety of the secondary battery 14.

[0058] Although embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other forms. Furthermore, various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Moreover, this embodiment is included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0059] 10. Secondary battery control system 12 BMS 14 Secondary battery 16 Inverters 18 MG 20 Vehicle ECU 22 Acquisition Department 22a 1st acquisition part 22b 2nd acquisition part 22c 3rd acquisition part 22d 4th acquisition part 24 Correction section 26 Control Unit 28 Memory section V11, V12, V13 Measured voltage values V2 Learning Target Values

Claims

1. A first acquisition unit acquires a power limit value that limits the power that can be input and output during charging and discharging of a secondary battery, A second acquisition unit acquires a measured voltage value indicating the voltage when power input and output exceeding a predetermined value is performed during the charging and discharging of the secondary battery. A correction unit that corrects the power limit value based on the measured voltage value, Equipped with, Secondary battery control system.

2. The system includes a third acquisition unit that acquires a target value as a learned target value for the measured voltage when power input and output exceeding a predetermined value is performed during charging and discharging. The correction unit corrects the power limit value so that the measured voltage value converges to a predetermined range including the learning target value. The secondary battery control system according to claim 1.

3. The secondary battery is equipped with a fourth acquisition unit that acquires learning regions that are divided according to the charge state and temperature of the secondary battery. The correction unit corrects the power limit value for each learning area based on the current charge state and temperature of the secondary battery. A secondary battery control system according to claim 1 or claim 2.

Images