Battery characteristic detection method and apparatus

Abstract

Device for detecting a characteristic of a rechargeable battery, comprising: a detector (31) for generating deterioration information representing a deterioration state (α, β, γ) of a rechargeable battery at a first time (t1), the detector generating the deterioration information based on: a first characteristic value (D1, R1) representing an actual deterioration state of the rechargeable battery at the first time (t1), a first reference value (Db, Rb) representing a virtual condition of a first virtual battery at the first time (t1), the first virtual battery having the same temperature (T1) as the rechargeable battery at the first time (t1), the first virtual battery exhibiting a deterioration in performance as it exists at a first reference time (tb) which is earlier than the first time (t1), and a second reference value (De, Re) representing a virtual condition of a second virtual battery at the first time (t1), the second virtual battery having the same temperature (T1) as the rechargeable battery at the first time (t1), the second virtual battery exhibiting a deterioration in performance as it exists at a second reference time (te) that is later than both the first reference time (tb) and the first time (t1), and an estimator (32) for estimating a characteristic value (D2, R2) of the rechargeable battery possibly representing a deterioration state of the battery at a second time (t2) based on the deterioration information generated by the detector and a degree of temperature (T2) of the rechargeable battery at the second time (t2), the second time (t2) being later than the first time (t1), wherein the deterioration information consists of a ratio (α) between a reference difference and a calculation difference, wherein the reference difference is a difference between the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time and the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time, wherein the calculation difference is a difference between the characteristic value (D, R) of the rechargeable battery actually detected at the first time and either the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time or the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time.

Description

BACKGROUNDTechnical field

[0001] The present disclosure relates to a battery characteristic detecting method and a battery characteristic detecting apparatus. background

[0002] Some control devices that control a battery mounted on a vehicle detect an internal resistance value of the battery and control use of the battery based on the detected resistance value, as discussed in, for example, Japanese Patent Application Laid-Open No. 2018-148720 (JP-2018-148720-A).

[0003] However, to accurately measure the battery's resistance, the battery must be charged and discharged with a certain amount of current flowing through its internal resistance. Therefore, depending on the battery type, the battery's resistance may not be measured immediately after the vehicle starts operating. If the resistance is unknown, battery usage cannot be controlled based on the resistance. Consequently, battery usage time is reduced, leading to a decrease in power consumption efficiency.

[0004] It is generally impossible to save and continuously use a battery resistance value acquired during a previous activation period after a momentary activation. That is, if the battery temperature at a momentary activation time is different from that in the previous activation period, the instantaneous battery resistance value will be different. This is because the battery resistance value exhibits temperature dependence.

[0005] As a countermeasure to such a problem, the method described below can be exemplified. That is, in the previous activation period, a ratio between a resistance value of the battery at that time and that of a fresh battery is calculated and stored as a coefficient indicating a deterioration state of the battery (hereinafter simply referred to as a deterioration coefficient). Then, after starting instantaneous operation, an instantaneous resistance value is estimated based on the stored deterioration coefficient and an instantaneous temperature. Thus, the resistance value is immediately obtained, and the battery can be used directly after starting instantaneous activation without waiting for an actual measurement of the resistance value.

[0006] However, the degradation coefficient is not completely constant regardless of temperature changes, and varies depending on the battery specification and temperature range, even if the battery is in the same degradation state. Therefore, if the temperature deviation between the previous activation period and the current activation time is large, the estimation of the current resistance value based on a previously calculated degradation coefficient may be inaccurate.

[0007] The occurrence of such a problem is not limited to the situation described above where the battery resistance value is estimated. That is, the same problem may occur when estimating other various characteristic values, such as a battery's charge capacity, etc.

[0008] The present invention is made to address the above-described problem, and an object thereof is to provide a system capable of accurately estimating a characteristic value of a currently used battery even when a deviation of a temperature of the battery between a time when deterioration thereof is previously detected and a current use time is large.

[0009] Document DE 11 2006 000 499 T5 discloses a battery condition monitoring device for monitoring the condition of a battery. According to the battery condition monitoring device, the lower voltage limit at the time a load is connected at an engine start time with a battery in a substantially new condition is measured as an initial reference lower limit voltage value. This initial reference lower limit voltage value, an initial reference open-circuit voltage or the open-circuit voltage of the battery, and the information pre-stored in a memory unit regarding a rate of change of the internal resistance depending on the change in the open-circuit voltage of the battery are used to derive the reference discharge characteristics of a new battery to the engine start load inherent in the vehicle.

[0010] JP 2015-171275 A discloses a charger and a charging method for a secondary battery capable of safely charging the secondary battery to a target charge amount by determining a charging termination condition by directly considering an internal resistance value of the secondary battery.

[0011] The document DE 11 2017 000 588 T5 discloses a battery state estimation device configured to estimate the state of a secondary battery based on a battery model of the secondary battery. SUMMARY

[0012] Accordingly, one aspect of the present disclosure provides a novel battery characteristic detection device comprising a detector (31) for generating deterioration information (α, β, γ) representing a deterioration state of a rechargeable battery at a first time (t1). The detector generates the deterioration information based on a characteristic value (D, R) representing an actual deterioration state of the rechargeable battery at the first time (t1) (D1, R1) and a first reference value (Db, Rb) representing a virtual condition of a first virtual battery at the first time (t1). The first virtual battery has the same temperature (T1) as the rechargeable battery at the first time (t1).The first virtual battery exhibits a deterioration in performance that it exhibits at a first reference time (tb) that is earlier than the first time (t1). The detector also generates the deterioration information based on a second reference value (De, Re) that represents a virtual condition of a second virtual battery at the first time (t1). The second virtual battery has the same temperature (T1) that the rechargeable battery has at the first time (t1). The second virtual battery exhibits a deterioration in performance that it exhibits at a second reference time (te) that is later than both the first reference time (tb) and the first time (t1).The battery characteristic detection device further comprises an estimator (32) for estimating a second characteristic value (D2, R2) of the rechargeable battery, possibly representing a deterioration state of the battery at a second time (t2), based on the deterioration information generated by the detector and a degree of temperature (T2) of the rechargeable battery at the second time (t2). The second time (t2) is later than the first time (t1). The deterioration information consists of a ratio (α) between a reference difference and a calculation difference.The reference difference is a difference between the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time point and the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time point. The calculation difference is a difference between the characteristic value (D, R) of the rechargeable battery actually detected at the first time point and either the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time point or the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time point.

[0013] Another aspect of the present disclosure provides a novel method of detecting a battery characteristic comprising the steps of: calculating a first resistance value (R1) in the rechargeable battery at a first time (t1); calculating a first deterioration resistance (Rb1) of a virtual new battery in a virtual new battery having the same temperature as the rechargeable battery at the first time; and calculating a first deterioration resistance (Re1) of a virtual battery at the end of its life in a virtual battery at the end of its life having the same temperature as the rechargeable battery at the first time.The method further comprises the steps of: calculating a first deterioration coefficient (Db1) of a new battery at the first time (t1) based on the first deterioration resistance (Rb1) of a virtual new battery and the first deterioration resistance (Re1) of a virtual battery at its end of life; calculating a first deterioration coefficient (D1) based on a first resistance value (R1) and the first deterioration resistance (Re1) of the virtual battery at its end of life; and calculating a deterioration value (α) based on the first deterioration coefficient (Db1) of the new battery, the first deterioration coefficient (D1), and a final-stage battery deterioration coefficient (De1).The method further comprises the steps of: calculating a second deterioration resistance (Rb2) of a virtual new battery in a virtual new battery having the same temperature as the rechargeable temperature at the second time (t2); calculating a second deterioration resistance (Re2) of a virtual battery at its end of life in a virtual battery at its end of life having the same temperature as the rechargeable battery at the second time (t2); and calculating a second deterioration coefficient (Db2) of a new battery at the second time based on the second deterioration resistance (Rb2) of the virtual new battery and the second deterioration resistance (Re2) of the virtual battery at its end of life.

[0014] The method further comprises the steps of: estimating a second deterioration coefficient (D2) based on the second deterioration coefficient (Db2) of the new battery and the deterioration value (α); calculating a resistance (R2) in the rechargeable battery at the second time point based on the second deterioration coefficient (D2) and the second deterioration resistance (Re2) of the virtual battery at its end of life; and using the resistance (R2) as control information. The deterioration value (α) is a ratio (α) between a reference difference and a calculation difference.The reference difference is a difference between the first deterioration coefficient (Db1) of the new battery of the first virtual battery, calculated based on the temperature at the first time, and the final-stage battery deterioration coefficient (De1) of the second virtual battery, calculated based on the temperature at the first time. The calculation difference is a difference between the first deterioration coefficient (D1) of the rechargeable battery actually detected at the first time and either the first deterioration coefficient (Db1) of a new battery of the first virtual battery, calculated based on the temperature at the first time, or the final-stage battery deterioration coefficient (De1) of the second virtual battery, calculated based on the temperature at the first time.

[0015] According to one aspect of the present disclosure, the detector detects deterioration information indicating deterioration of the battery at a first time. The estimation unit then estimates a characteristic value at a second time based on the deterioration information and the temperature of the battery at the second time. Consequently, the characteristic value at the second time can be estimated according to a change in temperature.

[0016] Furthermore, the deterioration information is determined based on two reference values ​​of the above-described first and second reference values. Therefore, the deterioration information can more accurately indicate a deterioration state of the battery than the deterioration coefficient defined based only on one reference value (e.g., a characteristic value of a fresh battery, a characteristic value of the battery at a terminal time). Therefore, even if a deviation in the temperature of the battery between the first time and the second time is large, the deterioration information is not greatly affected by the temperature and can more accurately indicate a deterioration state at each detection time.As a result, by estimating the characteristic value of the battery at the second time point based on the deterioration information, an estimation accuracy of the characteristic value can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete appreciation of the present disclosure and many of the attendant advantages of the present disclosure will be more readily obtained as the present disclosure becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: Fig. 1 is a circuit diagram schematically illustrating a battery characteristic detecting device according to a first embodiment of the present disclosure; Fig. 2 is a block diagram illustrating battery characteristic detection and estimation performed by the battery characteristic detection device; Fig. 3A to 3E are graphs collectively illustrating battery characteristic detection and estimation performed by the battery characteristic detection device; Fig. 4A and Fig. 4B Graphs each showing a relationship per deterioration value or the like between temperature and a deterioration coefficient of a battery; Fig. 5A to 5F graphs each illustrating a transition of an applicable value; Fig. 6A to 6C are graphs each illustrating battery characteristic detection and estimation performed by a battery characteristic detection apparatus according to a second embodiment of the present disclosure; Fig. 7A to 7C are graphs each illustrating battery characteristic detection and estimation performed by a battery characteristic detection apparatus according to a third embodiment of the present disclosure; and Fig. 8A to 8C are graphs each illustrating battery characteristic detection and estimation performed by a battery characteristic detection apparatus according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0018] Referring now to the drawings, in which like reference characters designate identical or corresponding parts throughout the several views thereof, and to Fig. 1 and applicable drawings, a first embodiment of the present disclosure will be described.

[0019] First, in Fig. 1 schematically illustrates a battery characteristic detecting device and its periphery of the first embodiment by means of a circuit diagram. As illustrated, a battery 10, a rotary electric machine 60, and a load 70 or the like are mounted in a vehicle in addition to a machine (not shown). A battery characteristic detecting device 20 is connected to the battery 10. A starter switch 80 is connected to the engine. The battery 10 has an internal resistance 13. A resistance value of the internal resistance 13 is referred to herein as a resistance value R of the battery 10. The battery characteristic detecting device 20 includes a reference value acquiring unit 25, a detector 31, and an estimator 32.

[0020] Although the battery 10 in this embodiment is a lithium battery, any other type of battery may be used. The load 70 includes various electrical devices or the like. The battery 10 supplies power to the electric rotary machine 60 and the load 70. In contrast, the battery 10 is supplied with power and charged with electricity by the electric rotary machine 60.

[0021] Now, terms used herein will be described first. That is, a value indicating a deterioration state of the battery 10 is referred to as a deterioration value α. In this embodiment, the deterioration value α corresponds to deterioration information in the claimed invention. A point in time at which a battery 10 is brand new is referred to as a new battery time tb. In this embodiment, the new battery time tb corresponds to a first reference time in the claimed invention. Furthermore, a point in time at which a predetermined period, such as 10 years, etc., has elapsed from the new battery time tb is referred to as a final stage time te. In this embodiment, the final stage time te corresponds to a second reference time in the claimed invention.

[0022] Furthermore, a given time point that comes after the new battery time point tb is referred to as a first time point t1. More specifically, in this embodiment, the first time point t1 is a time point when the detector 31 last detected the deterioration value α before the start switch 80 is turned off. A time point that comes a given time after the first time point t1 is referred to as a second time point t2. More specifically, in this embodiment, the second time point t2 is a time point when the start switch 80 is turned on for the first time after the start switch 80 is turned off after the first time point t1.

[0023] Furthermore, a temperature T of the battery 10 at the first time t1 is referred to as a first temperature T1, and a temperature T of the battery 10 at the second time t2 is referred to as a second temperature T2. Furthermore, a resistance value R of the battery 10 at the first time t1 is referred to as a first resistance value R1. A resistance value R of the battery 10 at the second time t2 is referred to as a second resistance value R2.

[0024] Furthermore, a resistance value R of the battery 10 with deterioration equivalent to a battery at time tb of a new battery, which varies according to the temperature T, is referred to as a new battery resistance value Rb. A resistance value Rb of a new battery at the first temperature T1 is referred to as a first new battery resistance value Rb1. A resistance value Rb of a new battery at the second temperature T2 is referred to as a second new battery resistance value Rb2.

[0025] Furthermore, a resistance value R of the battery 10 with deterioration equivalent to a battery at the final stage time te, which varies according to the temperature T, is referred to as a final stage resistance value Re. Furthermore, a final stage resistance value Re at the first temperature T1 is referred to as a first final stage resistance value Re1. A final stage resistance value Re at the second temperature T2 is referred to as a second final stage resistance value Re2.

[0026] Furthermore, a ratio (ie, R / Re) between a resistance value R of the battery 10 at a given target time and a final-stage resistance value Re of the battery 10 at a temperature T at the given time is referred to as a deterioration coefficient D. In this embodiment, the deterioration coefficient D corresponds to a characteristic value in the claimed invention. Furthermore, a deterioration coefficient D at the first time t1 is referred to as a first deterioration coefficient D1. A deterioration coefficient D at the second time t2 is referred to as a second deterioration coefficient D2.

[0027] Furthermore, a deterioration coefficient (D (ie, R / Re)) assigned to a battery 10 with deterioration equivalent to a battery at time tb of a new battery, which changes according to the temperature T, is referred to as a new battery deterioration coefficient Db. In this embodiment, the new battery deterioration coefficient Db corresponds to a first reference value in the claimed invention. Furthermore, a new battery deterioration coefficient Db at the first temperature T1 is referred to as a first new battery deterioration coefficient Db1. A new battery deterioration coefficient Db at the second temperature T2 is referred to as a second new battery deterioration coefficient Db2.

[0028] Furthermore, a deterioration coefficient D assigned to a battery 10 with deterioration equivalent to a battery at a terminal-stage time point te is referred to as a terminal-stage battery deterioration coefficient De. In this embodiment, the terminal-stage battery deterioration coefficient De corresponds to a second reference value in the claimed invention. Since the terminal-stage battery deterioration coefficient De is represented by a fractional expression Re / Re, it inevitably takes the value 1. Furthermore, a terminal-stage battery deterioration coefficient De at the first temperature T1 is referred to as a first terminal-stage battery deterioration coefficient De1. A terminal-stage battery deterioration coefficient De at the second temperature T2 is referred to as a second terminal-stage battery deterioration coefficient De2.Consequently, like the first end-stage battery deterioration coefficient De1, the second end-stage battery deterioration coefficient De2 inevitably becomes 1.

[0029] Now, an exemplary battery characteristic detection device 20 will be described in more detail below. That is, a reference value acquisition unit 25 is included and has a map representing a relationship between the temperature T of a battery 10 and a new battery resistance value Rb thereof. The reference value acquisition unit 25 also has another map representing a relationship between the temperature T of the battery 10 and a final-stage resistance value Re thereof. Each of these maps is acquired in advance based on an experiment or a specification of the battery 10 and the like. From these maps, the reference value acquisition unit 25 can acquire a new battery resistance value Rb and a final-stage resistance value Re corresponding to the temperature T at a target time (i.e., detection time) as needed.Furthermore, the reference value acquisition unit 25 may acquire a new battery deterioration coefficient Db (ie, Rb / Re) based on this new battery resistance value Rb and the final-stage resistance value Re. Then, the reference value acquisition unit 25 provides such an acquired numerical value to the detector 31.

[0030] Subsequently, the detector 31 calculates and detects a deterioration value α based on the first deterioration coefficient D1, the first new battery deterioration coefficient Db1, and the first final-stage battery deterioration coefficient De1. The estimator 32 then estimates a second deterioration coefficient D2 based on the deterioration value α, a second new battery deterioration coefficient Db2, and a second final-stage battery deterioration coefficient De2.

[0031] Now, an exemplary detection and estimation process or the like performed by the battery characteristic detection device 20 will be described in more detail with reference to a block diagram of Fig. 2. First, in step S101, the detector 31 calculates a first resistance value R1 of the battery 10 based on a voltage value and a current value obtained therefrom at a first time t1. Similarly, the reference value acquisition unit 25 calculates a first resistance value Rb1 of a new battery, a first final-stage resistance value Re1, and a first deterioration coefficient Db1 of a new battery (ie, Rb1 / Re1) based on a first temperature T1 (in step S102).

[0032] Subsequently, the detector 31 calculates a first deterioration coefficient D1 (i.e., R1 / Re1) based on the first resistance value R1 and the first final-stage resistance value Re1 (in step S103). Subsequently, in step S104, the detector 31 calculates a deterioration value α based on the first deterioration coefficient D1, the first new battery deterioration coefficient Db1, and a first final-stage battery deterioration coefficient De1 (i.e., the value 1), which will be described in more detail below.

[0033] Subsequently, in step S105, the reference value acquiring unit 25 calculates a second new battery resistance value Rb2, a second final-stage resistance value Re2, and a second new battery deterioration coefficient Db2 (i.e., Rb2 / Re2) based on the second temperature T2. Subsequently, in step S106, the estimator 32 estimates a second deterioration coefficient D2 based on the deterioration value α, a second new battery deterioration coefficient Db2, and a second final-stage battery deterioration coefficient De2 (i.e., the value 1), which will be described in more detail later. Subsequently, in step S107, the estimator 32 calculates a second resistance value R2 based on the second deterioration coefficient D2 (i.e., R2 / Re2) and the second final-stage resistance value Re2.

[0034] Then, in step S108, the second resistance value R2 as calculated and the deterioration value α calculated in the calculation process are used. Specifically, for example, information output from the battery 10 to the rotary electric machine 60 is obtained based on the second resistance value R2. Further, information output to each of the other loads 70 is also obtained based on the second resistance value R2, for example. Furthermore, information about a lifetime or the like of the battery 10 is also obtained based on the deterioration value α.

[0035] Fig. 3A to 3E are graphs collectively illustrating a relationship between the temperature T of the battery 10 and the deterioration coefficient D. When a rate of change of the resistance value Rb of the new battery to the temperature T is different from that of the final-stage resistance value Re to the temperature T, the deterioration coefficient Db of a new battery (i.e., Rb / Re) is not constant and varies according to the temperature T. Therefore, in this embodiment, in a range lower than a given temperature Tx, the deterioration coefficient Db shown in Fig. 3A, the deterioration coefficient Db of the new battery is not constant and varies according to the temperature T. In contrast, since the final-stage battery deterioration coefficient De (ie, Re / Re) is always the value 1 (ie, Re / Re), the final-stage battery deterioration coefficient De does not change according to the temperature T.

[0036] Consequently, in the range lower than the given temperature range Tx, a line of the new battery deterioration coefficient Db and that of the end-stage battery deterioration coefficient De are not parallel. In such a situation, even if the deterioration value α is calculated based only on either the new battery deterioration coefficient Db or the end-stage battery deterioration coefficient De, a deterioration state cannot be correctly estimated. Then, in view of this, a deterioration value α is sought based on both the new battery deterioration coefficient Db and the end-stage battery deterioration coefficient De, and the second resistance value R2 is estimated based on the deterioration value α.

[0037] Now, with reference to Fig. 3A to 3C, the above-described calculation of the deterioration value α, which is carried out in step S104, is described in more detail. First, as in Fig. 3A, on a graph showing a relationship between a deterioration coefficient D and the temperature T, a point indicating a state of the battery 10 at a time t1 is plotted. That is, a first point P1 (coordinate points: T1, D1) indicating a first temperature T1 and a first deterioration coefficient D1 is plotted.

[0038] Below, as in Fig. 3B, a point indicating a deterioration coefficient Db at the first temperature T1 is plotted. That is, a first new-battery point Pb1 (coordinate points: T1, Db1) indicating the first temperature T1 and a first new-battery deterioration coefficient Db1 is plotted. Next, a point indicating a final-stage battery deterioration coefficient De at the first temperature T1 is plotted. That is, a first final-stage point Pe1 (coordinate points: T1, 1) indicating the first temperature T1 and a first final-stage battery deterioration coefficient De1 (i.e., the value 1) is plotted.

[0039] Below, as in Fig. 3C, to calculate a relative value (ie, D1 - Db1) and obtain a deterioration value α, the formula described below is calculated, assuming a difference between the first terminal stage point Pe1 and the first new battery point Pb1 (ie, 1 - Db1) as a unit difference (ie, the value 1 as indicated by an arrow in each of Fig. 3C and Fig. 3E). α=(D1−Db1) / (1−Db1)

[0040] Now, an estimation of a second deterioration coefficient D2, which is carried out in step S106, is made with reference to Fig. 3D and Fig. 3E. Specifically, as described in Fig. 3D, a point indicating a deterioration coefficient Db of a new battery at a second temperature T2 is plotted. That is, a second new-battery point Pb2 (coordinate points: T2, Db2) indicating the second temperature T2 and a second deterioration coefficient Db2 of a new battery is plotted. Next, a point indicating a final-stage battery deterioration coefficient De at the second temperature T2 is plotted. That is, a second final-stage point Pe2 (coordinate points: T2, 1) indicating the second temperature T2 and a second final-stage battery deterioration coefficient De2 (i.e., the value 1) is plotted.

[0041] Below, as in Fig. 3E, in order to identify and estimate a second point P2 (coordinate points: T2, D2) and thereby estimate a second deterioration coefficient D2 at a second temperature T2, such a new point is calculated. That is, first, a difference along the D-axis between the second final-stage point Pe2 and the second new-battery point Pb2 (i.e., (1 - Db2)) is multiplied by the deterioration value α. Then, the calculation result (i.e., α × (1 - Db2)) is added to a coordinate of the deterioration coefficient Db2 of the second new-battery point Pb2 (coordinate points: T2, Db2) to obtain the new point.

[0042] Furthermore, Fig. 4A is a graph showing a relationship between a deterioration coefficient D and a temperature T per deterioration value α. Fig. 4B is a graph illustrating a relationship between a deterioration coefficient D and a temperature T per deterioration corresponding to one year Y. The deterioration corresponding to one year Y indicates a deterioration level of the battery 10 per year. As shown, the relationship between the deterioration coefficient D and the temperature T when the deterioration value α is constant is similar to the relationship between the deterioration coefficient D and the temperature T when the deterioration corresponding to year Y is constant. Therefore, the deterioration corresponding to year Y can be calculated based on the deterioration value α.

[0043] Fig. 5A to 5F are graphs collectively illustrating a transition of different values ​​when the deterioration value α is detected at the first time t1 and the second resistance value R2 is estimated at the second time t2, as described above. Specifically, Fig. 5A is a graph illustrating a transition of ON states and OFF states of the start switch 80. Hereinafter, turning on the start switch 80 is simply referred to as start-ON, while turning off the start switch 80 is simply referred to as start-OFF. Fig. 5B is a graph illustrating a transition of a temperature T of the battery 10. Fig. Figure 5C is a graph showing a measurement time point for measuring a resistance value R. Fig. 5D is a graph indicating a transition of the resistance value R of the battery 10. Fig. Figure 5E is a graph illustrating a transition of a deterioration coefficient D. Fig. Figure 5F is a graph illustrating a transition of a deterioration value α.

[0044] As in Fig. 5C, the first resistance value R1 is measured at the first time t1 during a start-ON period shown in Fig. 5A. Consequently, as shown in Fig. 5D to 5F, the first resistance value R1, the first deterioration coefficient D1 and the deterioration value α are detected at the time. Subsequently, as shown in Fig. 5A, a start-OFF state is established at a given start-OFF time ti which is later than the first time t1.

[0045] Furthermore, if the temperature T of the battery 10 changes after the start-OFF time ti, as in Fig. 5B, an actual resistance value R changes as shown by a dashed line in Fig. 5D, and an actual deterioration coefficient D changes just as easily. In contrast, as shown by a dashed line in Fig. As shown in Figure 5F, the deterioration value α hardly changes.

[0046] Subsequently, when the start-ON state is at the second time t2 which is later than the start-OFF time ti as shown in Fig. 5A, a second deterioration coefficient D2 is estimated based on the deterioration value α as stored, and a second resistance value R2 is calculated based on the second deterioration coefficient D2 as estimated, as shown in Fig. 5D to 5F respectively.

[0047] In contrast, in a comparative example, the first deterioration coefficient D1 is stored instead of the deterioration value α, and a resistance value R at the second time t2 is estimated based on the first deterioration coefficient D1. In such a situation, since the first deterioration coefficient D1 is different from a deterioration coefficient D at the second time t2, a resistance value R calculated based on the first deterioration coefficient D1 becomes different from an actual resistance value R.

[0048] Below, as in Fig. 5C, an actual resistance value R is measured at a measurement time tj later than the second time t2. Accordingly, according to this embodiment, as shown in Fig. 5D and Fig. 5E, the deterioration coefficient D and the resistance value R, which are closer to these actual values, can be estimated between the second time point t2 and the actual measurement time point tj, in comparison with the comparative example.

[0049] According to this embodiment, by estimating the second resistance value R2, the resistance value R can be obtained immediately at the second time t2 without waiting for the actual measurement thereof at the measurement time tj. Therefore, at the second time t2 and thereafter, the battery 10 can be used immediately, and accordingly, the battery 10 can be used longer. Consequently, the rotating electric machine 60 can be driven longer, and regenerative power generation by the rotating electric machine 60 can be performed longer, thereby enabling improvement in electric power consumption.

[0050] Furthermore, according to this embodiment, the deterioration value α and the second resistance value R2 are calculated based on the deterioration coefficient D as described above. Therefore, when a deterioration coefficient D is determined in another use, the deterioration value α and the second resistance value R2 can be calculated based on the deterioration coefficient D determined in another use. Furthermore, since the final-stage battery deterioration coefficient De (ie, Re / Re) is always 1 when the deterioration coefficient D (ie, R / Re) is used, the reference value acquisition unit 25 does not need to acquire the first final-stage battery deterioration coefficient De1 and the second final-stage battery deterioration coefficient De2, thereby enabling simplified calculation.Furthermore, by converting the deterioration information into the deterioration value α as a numerical value, the deterioration information can be simplified. Furthermore, since a time when the detector 31 finally detects a deterioration value α before the start switch 80 is turned off is considered and used as the first time point t1, the resistance value R at the second time point t2 can be estimated as late as possible based on the final deterioration value α.

[0051] Now, a second embodiment will be described below mainly based on a difference from the first embodiment with reference to Fig. 6A to 6C. Specifically, in this embodiment, a constant deterioration line β is searched instead of the deterioration value α. Thus, in this embodiment, the constant deterioration line β corresponds to the deterioration information in the claimed invention.

[0052] Special are Fig. 6A to 6C are graphs collectively illustrating a relationship between a temperature T of a battery 10 and a deterioration coefficient D. Detection of the constant deterioration line β and estimation of a second deterioration coefficient D2 are performed as described below. First, as in Fig. 6A, a first point P1 (coordinate points: T1, D1) is drawn.

[0053] Then, as in Fig. 6B, a constant deterioration line β passing through the first point P1 is calculated. The constant deterioration line β is a line indicating a relationship between a deterioration coefficient D and a temperature T of the battery 10 in a given deterioration state of the battery 10. The constant deterioration line β is determined based on the deterioration coefficient Db of a new battery and the final-stage battery deterioration coefficient De. Therefore, the constant deterioration line β is drawn and extends along an average line extending between a line indicating the deterioration coefficient Db of a new battery and that indicating the final-stage battery deterioration coefficient De (ie, 1).Specifically, the constant deterioration line β may be a collection of points with the same deterioration values ​​α referred to in the first embodiment, for example.

[0054] In the drawing, a comparative example shown by a dashed line indicates a constant deterioration line β on which the deterioration coefficient D (ie, R / Re) is constant. That is, the constant deterioration line β is drawn based on the final-stage battery deterioration coefficient De (ie, Re / Re = 1) and not based on the deterioration coefficient Db of the new battery (ie, Rb / Re). Therefore, as shown in the drawing, in this comparative example, the constant deterioration line β extends along the line indicating the final-stage battery deterioration coefficient De (ie, 1). However, the constant deterioration line β does not extend along the average line drawn between the line indicating the deterioration coefficient Db of a new battery and that indicating the final-stage battery deterioration coefficient De (ie,1) indicates what is different from this embodiment.

[0055] Then, as in Fig. 6C, an intersection point of a second temperature T2 and the constant deterioration line β is calculated as a second point P2 (coordinate points: T2, D2).

[0056] Therefore, according to this embodiment, the second deterioration coefficient D2 can be directly estimated from the constant deterioration line β and the second temperature T2 only by searching the constant deterioration line β without calculating the first new-battery point Pb1, the first final-stage point Pe1, the second new-battery point Pb2, and the second final-stage point Pe2.

[0057] Now, a third embodiment will be described below mainly based on a difference from the second embodiment with reference to Fig. 7A to 7C. Specifically, in this embodiment, the second resistance value R2 is directly estimated from the first resistance value R1 without finding the first deterioration coefficient D1 or the second deterioration coefficient D2. That is, the second resistance value R2 is estimated from the first resistance value R1 using a constant deterioration line γ that is different from the constant deterioration line β.

[0058] Therefore, in this embodiment, not the deterioration coefficient D (i.e., R / Re), but a resistance value R itself corresponds to a characteristic value in the claimed invention. Furthermore, the constant deterioration line γ corresponds to the deterioration information in the claimed invention, as described below.

[0059] That means, Fig. 7A to 7C are graphs illustrating a relationship between the temperature T of the battery 10 and a resistance value R thereof. Detection of the constant deterioration line γ and estimation of the second resistance value R2 are performed as described below. First, how Fig. As shown in Figure 7A, a first point P1 (coordinate points: T1, R1) is drawn.

[0060] Below, as in Fig. 7B, a constant deterioration line γ passing through the first point P1 is calculated. Here, the constant deterioration line γ is a line indicating a relationship between the resistance value R and the temperature T of the battery 10 in the same deterioration state. The constant deterioration line γ is determined based on the resistance value Rb of a new battery and the final-stage resistance value Re. Therefore, the constant deterioration line γ is drawn along an average line extending between a line indicating the resistance value Rb of a new battery and a line indicating the final-stage resistance value Re.

[0061] Furthermore, a comparative example shown by a dashed line in the drawing is a constant deterioration line y drawn by accumulating points where the deterioration coefficient D (ie, R / Re) is the same. Specifically, the comparative example line is a constant deterioration line γ drawn not based on the resistance value Rb of a new battery, but based on the final-stage resistance value Re. Therefore, in this comparative example, the constant deterioration line γ extends along the line indicating the final-stage resistance value Re. However, the constant deterioration line γ of the comparative example does not extend along an average line drawn between the line indicating the resistance value R of a new battery and that indicating the final-stage resistance value Re at the same time, which is different from this embodiment.

[0062] Below, as in Fig. 7C, an intersection point of the second temperature T2 and the constant deterioration line γ is calculated as a second point P2 (coordinate points: T2, R2).

[0063] According to this embodiment, even if the first deterioration coefficient D1 (ie, R1 / Re1) and the second deterioration coefficient D2 (ie, R2 / Re2) are calculated, the second resistance value R2 can be directly estimated from the first resistance value R1.

[0064] Now, a fourth embodiment will be described below based on a difference from the second embodiment with reference to Fig. 8A to 8C.

[0065] That means, Fig.8A to 8C are graphs indicating a relationship between temperature T and resistance R of a battery 10. In this embodiment, a constant deterioration line β changes gradually as shown. Therefore, according to this embodiment, an amount of information on the constant deterioration line β can be reduced, enabling a simplified process.

[0066] Modifications to the various embodiments described above will be described below. The engine may be replaced with various operational power devices, such as a motor or a hybrid of an engine and a motor, etc. Furthermore, instead of a new battery time tb, a deterioration time corresponding to one year may be used. Likewise, instead of the final stage time te, a deterioration time corresponding to five years may be used.

[0067] Furthermore, in each of the first, second, and fourth embodiments, as the deterioration coefficient D, instead of the ratio (R / Re) between the final-stage resistance value Re and the resistance value R at the given time, a ratio (i.e., R / Rb) between the resistance value Rb of a new battery and the resistance value R at the given time may be used. In such a situation, instead of the final-stage battery deterioration coefficient De, the deterioration coefficient Db of a new battery is always 1.

[0068] Furthermore, similar to the third embodiment realized based on the second embodiment by replacing the deterioration coefficient D with the resistance value R as the characteristic value, another modification can be realized based on one of the first and fourth embodiments by replacing the deterioration coefficient D with the resistance value R as the characteristic value. Therefore, in the new modification realized based on one of the first and fourth embodiments, the second resistance value R2 can be directly estimated from the first resistance value R1 without calculating the first deterioration coefficient D1 (ie, R1 / Re1) and the second deterioration coefficient D2 (ie, R2 / Re2) as in the third embodiment.

[0069] Furthermore, instead of the calculation time for calculating the deterioration value α and the constant deterioration curves β and γ, which are performed before each start-off state, one can use, for example, once a month or once in a given period, etc. That is, a chronological change in the deterioration state is usually moderate.

[0070] Furthermore, estimation of the second resistance value R2 based on the deterioration value α and the constant deterioration lines β and γ may be performed only when a temperature degree difference between the first temperature T1 and the second temperature T2 is a predetermined level or more. Otherwise, that is, when the temperature degree difference between them is smaller than the predetermined level, either the first resistance value R1 is transferred and used as the second resistance value R2, or the first deterioration coefficient D1 is transferred and used as the second deterioration coefficient D2.

[0071] Furthermore, a ratio of a change in a deterioration coefficient Db of a new battery relative to the temperature T and a ratio of a change in a final-stage battery deterioration coefficient De relative to the temperature T may be the same. That is, the battery characteristic detecting device 20 can advantageously handle such a situation, in addition to the situation where these ratios are different from each other.

[0072] Furthermore, when a resistance value R does not change slightly due to a difference in a state of charge (ie, SOC) of the battery 10 or in a similar situation, a second resistance value R2 may be additionally corrected according to the SOC.

[0073] Furthermore, a battery capacity may be used instead of the resistance value R. That is, in each of the first, second, and fourth embodiments, instead of denoting the ratio (ie, R / Re) between the final-stage resistance value Re and the resistance value R at the given time, a ratio between a final-stage battery capacity and a battery capacity at a given time may be used as the deterioration coefficient D. Similarly, in the third embodiment, the resistance value R may be replaced with the battery capacity.

[0074] A battery characteristic detection device comprises a detector (31) for generating deterioration information representing a deterioration state (α, β, γ) of a battery at a first time (t1). The deterioration information is generated based on a first characteristic value (D1, R1) representing an actual deterioration state of the battery at the first time (t1), and first and second reference values ​​(Db, Rb) representing virtual conditions of first and second virtual batteries at the first time (t1), which are calculated based on a degree of temperature (T1) at the first time (t1). The first virtual battery exhibits deterioration as it exists at a second reference time (tb) that is earlier than the first time (t1).The second virtual battery exhibits deterioration as it exists at a second reference time (te), which is later than the first reference time (tb) and the first time (t1). An estimator (32) estimates a second characteristic value (D2, R2) of the rechargeable battery, possibly representing a deterioration state of the rechargeable battery at a second time (t2), based on the deterioration information and a degree of temperature (T2) of the rechargeable battery at the time (t2).

Claims

[1] Device for detecting a characteristic of a rechargeable battery, comprising: a detector (31) for generating deterioration information representing a deterioration state (α, β, γ) of a rechargeable battery at a first time (t1), the detector generating the deterioration information based on: a first characteristic value (D1, R1) representing an actual deterioration state of the rechargeable battery at the first time (t1), a first reference value (Db, Rb) representing a virtual condition of a first virtual battery at the first time (t1), the first virtual battery having the same temperature (T1) as the rechargeable battery at the first time (t1), the first virtual battery exhibiting a deterioration in performance as it exists at a first reference time (tb) which is earlier than the first time (t1), and a second reference value (De, Re) representing a virtual condition of a second virtual battery at the first time (t1), the second virtual battery having the same temperature (T1) as the rechargeable battery at the first time (t1), the second virtual battery exhibiting a deterioration in performance as it exists at a second reference time (te) that is later than both the first reference time (tb) and the first time (t1), and an estimator (32) for estimating a characteristic value (D2, R2) of the rechargeable battery possibly representing a deterioration state of the battery at a second time (t2) based on the deterioration information generated by the detector and a degree of temperature (T2) of the rechargeable battery at the second time (t2), the second time (t2) being later than the first time (t1), wherein the deterioration information consists of a ratio (α) between a reference difference and a calculation difference, wherein the reference difference is a difference between the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time and the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time, wherein the calculation difference is a difference between the characteristic value (D, R) of the rechargeable battery actually detected at the first time and either the first reference value (Db, Rb) of the first virtual battery calculated based on the temperature at the first time or the second reference value (De, Re) of the second virtual battery calculated based on the temperature at the first time. [2] A rechargeable battery characteristic detecting apparatus according to claim 1, wherein the first reference time (tb) is a time when a new battery is used for the first time, the second reference time (te) is a time when a predetermined time period has elapsed after the first reference time and the rechargeable battery is to be replaced. [3] A rechargeable battery characteristic detecting apparatus according to claim 1, wherein the characteristic value is determined based on an internal resistance value (R) of the rechargeable battery. [4] A rechargeable battery characteristic detecting apparatus according to any one of claims 1 and 3, wherein the characteristic value is a ratio (D) between a physical characteristic value (R) of the rechargeable battery actually detected at one of the first and second timings and a physical characteristic value (Re) of one of the first and second virtual batteries detected at a corresponding one of the first and second timings. [5] A rechargeable battery characteristic detecting apparatus according to any one of claims 1 and 4, wherein the deterioration information consists of information (β, γ) indicating a relationship between the characteristic value (R, D) and a temperature (T1) of the rechargeable battery in a deterioration state at the first time point. [6] A rechargeable battery characteristic detecting apparatus according to any one of claims 1 and 5, wherein the rechargeable battery is a battery mounted on a vehicle, wherein the first time point is a time point when the detector detects the deterioration information for the last time before a start switch (80) included in a power device for driving the vehicle is turned off. [7] A rechargeable battery characteristic detecting apparatus according to any one of claims 1 and 6, wherein a relationship between a change in a first reference value and a change in temperature and a relationship between a change in a second reference value and a change in temperature are different from each other in a given temperature detecting range. [8] A method of detecting a characteristic of a rechargeable battery, comprising the steps of: Calculating a first resistance value (R1) in the rechargeable battery at a first time (t1); Calculating a first deterioration resistance (Rb1) of a virtual new battery in a virtual new battery having the same temperature as the rechargeable temperature at the first time point; Calculating a first deterioration resistance (Re1) of a virtual battery at the end of its life in a virtual battery at the end of its life having the same temperature as the rechargeable battery at the first time point; Calculating a first deterioration coefficient (Db1) of a new battery at the first time (t1) based on the first deterioration resistance (Rb1) of the virtual new battery and the first deterioration resistance (Re1) of the virtual battery at its end of life; Calculating a first deterioration coefficient (D1) based on a first resistance value (R1) and the first deterioration resistance (Re1) of the virtual battery at its end of life; Calculating a deterioration value (α) based on the first deterioration coefficient (Db1) of a new battery, the first deterioration coefficient (D1) and a final-stage battery deterioration coefficient (De1); Calculating a second deterioration resistance (Rb2) of a virtual new battery in a virtual new battery having the same temperature as the rechargeable battery at the second time (t2); Calculating a second deterioration resistance (Re2) of a virtual battery at the end of its life in a virtual battery at the end of its life having the same temperature as the rechargeable temperature at the second time (t2); Calculating a second deterioration coefficient (Db2) of a new battery at the second time based on the second deterioration resistance (Rb2) of the virtual new battery and the second deterioration resistance (Re2) of the virtual battery at its end of life; Estimating a second deterioration coefficient (D2) based on the second deterioration coefficient (Db2) of the new battery and the deterioration value (α); Calculating a resistance (R2) in the rechargeable battery at the second time based on the second deterioration coefficient (D2) and the second deterioration resistance (Re2) of a virtual battery at its end of life; and Using the resistor (R2) as control information, where the deterioration value (α) is a ratio (α) between a reference difference and a calculation difference, wherein the reference difference is a difference between the first deterioration coefficient (Db1) of a new battery of the first virtual battery, which is calculated based on the temperature at the first time, and the final-stage battery deterioration coefficient (De1) of the second virtual battery, which is calculated based on the temperature at the first time, wherein the calculation difference is a difference between the first deterioration coefficient (D1) of the rechargeable battery actually detected at the first time point and either the first deterioration coefficient (Db1) of a new battery of the first virtual battery calculated based on the temperature at the first time point or the final-stage battery deterioration coefficient (De1) of the second virtual battery calculated based on the temperature at the first time point.

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