Deterioration amount estimation device, power storage system, degradation amount estimation method, and computer program product

Abstract

The degradation amount estimation device (31) comprises: a calculation unit (CPU33) for calculating the degradation amount of the storage element (1); and an estimation unit (CPU33) for estimating the transient degradation amount based on the degradation amount calculated by the calculation unit and the continuous degradation amount that does not decrease with the passage of time but continues. The transient degradation amount is estimated, and input and output restrictions of the storage element 1 are performed, etc., to suppress the increase of the continuous degradation amount.

Description

Technical Field

[0001] The present invention relates to a degradation amount estimation device for estimating the degradation amount of a chargeable and dischargeable power storage element, a power storage system, a degradation amount estimation method, and a computer program product. Background Art

[0002] There are known charge and discharge control devices that control the charge and discharge of secondary batteries used in vehicles such as electric vehicles (EV) and hybrid vehicles (HEV), and secondary batteries used in industries such as power storage devices and solar power generation systems.

[0003] The charge and discharge control device disclosed in Patent Document 1 includes: a discharge control unit that stops discharging when the voltage is lower than a predetermined reference value during discharge; a charge control unit that stops charging when the voltage exceeds a predetermined reference value during charging; and a history estimation unit that estimates the battery history (charge and discharge times, cycle times) based on the battery state. The discharge control unit corrects (increases) the reference value for stopping discharge based on the history estimation value of the history estimation unit, and the charge control unit corrects (decreases) the reference value for stopping charging based on the history estimation value of the history estimation unit.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: (Japan) Patent Publication No. 7-255133 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] The charge and discharge control device disclosed in Patent Document 1 is a structure that corrects the reference voltage value for stopping discharge and the reference voltage value for stopping charge based only on the estimated value of the history record (charge and discharge times, cycle times) of the secondary battery. Therefore, due to the difference in the magnitude of the current during charge and discharge of the secondary battery, the deterioration of the secondary battery may not be suppressed.

[0009] The inventors of the present application have discovered that the degradation (decline in output performance) of the storage element includes transient degradation (transient decline in output performance) and continuous degradation (continuous decline in output performance). Transient degradation is a transient degradation phenomenon caused by the depletion of the electrolyte in the electrode due to ion segregation in the electrolyte during charging and discharging. Transient degradation will recover when the load is low and no degradation occurs. If the amount of transient degradation increases, continuous degradation that will not recover will occur even if the storage element is in a low load state.

[0010] An object of the present invention is to provide a degradation amount estimation device, a power storage system, a degradation amount estimation method, and a computer program product that can estimate the transient degradation amount well and suppress an increase in the continuous degradation amount.

[0011] Technical solutions to solve problems

[0012] A degradation amount estimation device according to one aspect of the present invention includes: a calculation unit that calculates the degradation amount of an electric storage element; and an estimation unit that estimates the transient degradation amount based on the degradation amount and a continuous degradation amount that does not decrease (recover) with the passage of time but continues.

[0013] Effects of the Invention

[0014] According to one aspect of the present invention, the transient degradation amount is estimated based on the calculated degradation amount and the continuous degradation amount. By extracting the transient degradation amount from the degradation amount and limiting the application of the storage element, input and output restrictions are performed, thereby suppressing the increase of the continuous degradation amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a perspective view of the electric storage element of the first embodiment.

[0016] Figure 2 yes Figure 1 Sectional view along line II-II.

[0017] Figure 3 It is a block diagram of a power storage device.

[0018] Figure 4 This is a graph showing the relationship between ignition-on (IG-on) and ignition-off (IG-off) and changes in output performance.

[0019] Figure 5 This is a graph showing the relationship between the elapsed time from immediately after the vehicle is mounted and the internal resistance value.

[0020] Figure 6 This is a graph showing the relationship between the elapsed time and the internal resistance value when IG-off, IG-on, IG-off, and IG-on are repeated.

[0021] Figure 7 This is a graph showing the relationship between the elapsed time and the internal resistance value when the continuous degradation amount is quantified and then IG-off, IG-on, and IG-off are repeated.

[0022] Figure 8 This is a graph showing the results of investigating the relationship between the standing time after IG-off and the transient degradation amount.

[0023] Fig. 9This is a flowchart showing the processing procedure of the CPU estimating the amount of continuous degradation.

[0024] Fig.10 This is a flowchart showing the processing procedure of the CPU estimating the transient degradation amount and controlling the transient degradation.

[0025] Fig.11 This is a flowchart showing the processing procedure of estimating the transient degradation amount and controlling the transient degradation by the CPU according to the second embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, the present invention will be described in detail based on the drawings showing the embodiments.

[0027] (Overview of this embodiment)

[0028] A degradation amount estimation device according to one embodiment includes: a calculation unit that calculates the degradation amount of an electric storage element; and an estimation unit that estimates the transient degradation amount based on the degradation amount and a continuous degradation amount that does not decrease with the passage of time but continues.

[0029] According to the above structure, the transient degradation amount is estimated based on the calculated degradation amount and the continuous degradation amount. When the degree of transient degradation increases, the continuous degradation accelerates. By quantifying the transient degradation and limiting the input and output of the storage element, the increase in the continuous degradation amount can be suppressed. Therefore, the life of the storage element (or storage device) can be extended.

[0030] A degradation amount estimating device according to another embodiment includes: a first calculating unit that calculates a calculated degradation amount of a power storage element; and a first estimating unit that estimates a transient degradation amount based on the calculated degradation amount at a calculation time and the calculated degradation amount at a predetermined time.

[0031] The calculation time is an arbitrary time at which the calculation degradation amount is calculated.

[0032] According to the above configuration, the transient degradation amount can be estimated and controlled by finding, for example, the increase amount or ratio of the degradation amount based on the calculated degradation amount at the calculation time and the calculated degradation amount at a predetermined time after the calculation time.

[0033] The degradation amount estimating device may include a second calculation unit that calculates an internal resistance value of the power storage element, and the first calculation unit may calculate the degradation amount based on the internal resistance value calculated by the second calculation unit.

[0034] According to the above configuration, the amount of degradation can be easily calculated from the amount of increase in the internal resistance value.

[0035] In the above-mentioned degradation amount estimating device, the above-mentioned specified time is the time when the calculated degradation amount decreases when the load is smaller than the specified value and the decrease time during which the decrease amount converges has passed. The degradation amount estimating device includes a second estimating unit, which estimates the continuous continuous degradation amount based on the calculated degradation amount calculated by the above-mentioned first calculation unit at the above-mentioned time. The above-mentioned first estimating unit can also estimate the above-mentioned transient degradation amount based on the calculated degradation amount at the above-mentioned calculation time and the above-mentioned continuous degradation amount.

[0036] “When the load is smaller than the prescribed value” means when the load is so small that it does not affect the transient degradation, and also includes when there is no load.

[0037] “The decrease amount converges” means that the transient degradation amount decreases and converges.

[0038] According to the above configuration, the calculated degradation amount after the decrease time has passed is estimated as the continuous degradation amount. The continuous degradation amount does not decrease over time but continues, so by controlling the transient degradation amount obtained based on the calculated degradation amount and the continuous degradation amount, the increase of the continuous degradation amount can be well suppressed.

[0039] In the above-mentioned degradation amount estimating device, the second estimating unit may estimate the continuous degradation amount when a predetermined period of time has elapsed and the load is smaller than the predetermined value.

[0040] As described above, since the amount of continuous degradation does not decrease but continues, the amount of transient degradation can be estimated based on the calculated degradation amount and the amount of continuous degradation. However, in the long run, the amount of continuous degradation increases. Considering the allowable error of estimating the amount of transient degradation, etc., an interval (prescribed period) for estimating the amount of continuous degradation is set. That is, by updating the amount of continuous degradation when a prescribed period has passed since the last time the amount of continuous degradation was calculated, the amount of transient degradation can be estimated with good accuracy.

[0041] The degradation amount estimating device may further include a setting unit configured to set the decrease time based on a use condition of the power storage element and a predetermined convergence value of the decrease amount.

[0042] According to the above configuration, the decrease time is approximately set based on the usage conditions of the power storage element and a predetermined convergence value of the decrease amount, so that the transient degradation amount can be estimated realistically and accurately.

[0043] A power storage system according to another embodiment includes a power storage element, any one of the above-described degradation amount estimating devices, and a regulator that regulates the amount of current input to and output from the power storage element so that the transient degradation amount of the power storage element becomes equal to or less than a predetermined value.

[0044] According to the above configuration, by estimating and controlling the transient degradation amount, it is possible to suppress an increase in the persistent degradation amount.

[0045] A degradation amount estimation device according to another embodiment includes: a calculation unit that calculates the degradation amount of the storage element; and an estimation unit that estimates the continuous degradation amount based on the degradation amount calculated by the calculation unit when the degradation amount decreases when the load of the storage element is smaller than a specified value and a decrease time for the decrease amount to converge has passed.

[0046] According to the above configuration, the amount of continuous degradation can be estimated favorably, and the internal state of the power storage element can be estimated.

[0047] A degradation amount estimation method according to another embodiment calculates the degradation amount of the power storage element, and estimates the transient degradation amount based on the calculated degradation amount and the continuous degradation amount that does not decrease with the passage of time but continues.

[0048] A computer program product according to another embodiment includes a computer program that, when executed, implements processing for calculating a degradation amount of a power storage element and estimating a transient degradation amount based on the calculated degradation amount and a continuous degradation amount that continues without decreasing over time.

[0049] According to the above configuration, the transient degradation amount is estimated based on the calculated degradation amount and the continuous degradation amount. By quantifying the transient degradation and limiting the input and output of the power storage element, it is possible to suppress an increase in the continuous degradation amount.

[0050] A degradation amount estimation method according to another embodiment calculates a calculated degradation amount of an electric storage element, and estimates a transient degradation amount based on the calculated degradation amount at a calculation time and the calculated degradation amount at a predetermined time.

[0051] A computer program product according to another embodiment includes a computer program that, when executed, implements processing for calculating a calculated degradation amount of a power storage element and estimating a transient degradation amount based on the calculated degradation amount at a calculation time and the calculated degradation amount at a predetermined time.

[0052] According to the above configuration, the transient degradation amount can be estimated based on the calculated degradation amount at the calculation time and the calculated degradation amount at the predetermined time, and the transient degradation amount can be controlled.

[0053] (First Embodiment)

[0054] Figure 1 is a perspective view of an electric storage element (hereinafter referred to as a battery) 1 according to the first embodiment. Figure 2 yes Figure 1 Hereinafter, a case where the battery 1 is a lithium ion secondary battery will be described, but the battery 1 is not limited to a lithium ion secondary battery.

[0055] The battery 1 includes a case 11 having a cover plate 2 and a case body 3 , a positive electrode terminal 4 , insulating plates 5 and 9 , a negative electrode terminal 8 , gaskets 6 and 10 , a rupture valve 20 , current collectors 7 and 12 , and an electrode body 13 .

[0056] The case 11 is made of metal such as aluminum, aluminum alloy, stainless steel, or synthetic resin, and is formed in a rectangular parallelepiped shape to accommodate the electrode body 13 and an electrolyte (not shown).

[0057] like Figure 2 As shown, the positive electrode terminal 4 includes a shaft portion 41 penetrating the cover plate 2 , a caulking portion 42 to which one end of the shaft portion 41 is caulked, and a plate portion 43 provided at the other end of the shaft portion 41 .

[0058] The gasket 6 is made of synthetic resin such as vertical polyphenylene sulfide (PPS) or polypropylene (PP). The positive electrode terminal 4 penetrates the cover plate 2 while the inner surface of the plate portion 43 and the shaft portion 41 are covered and insulated by the gasket 6 .

[0059] The insulating plate 5 is made of a synthetic resin such as PPS or PP, and includes an insertion hole 50 through which the end of the shaft portion 41 is inserted, and a housing portion 51 for housing a joining portion 71 described below.

[0060] The current collector 7 is made of aluminum plate, for example, and is disposed on the inner surface of the cover plate 2. The current collector 7 has an insertion hole 70 for inserting the end of the shaft 41. The current collector 7 has a joint portion 71 protruding outward from the other portions at the center of the cover plate 2 and jointed with the positive electrode tab 14.

[0061] The negative terminal 8 includes a shaft portion 81 penetrating the cover plate 2, a rivet portion 82 to which one end of the shaft portion 81 is rivet, and a plate portion 83 provided at the other end of the shaft portion 81. The negative terminal 8 penetrates the cover plate 2 while the inner surface of the plate portion 83 and the shaft portion 81 are covered and insulated by a gasket 10 made of, for example, PPS or PP.

[0062] The insulating plate 9 is made of a synthetic resin such as PPS or PP, and includes an insertion hole 90 through which the end of the shaft portion 81 is inserted, and a housing portion 91 for housing a joining portion 121 described below.

[0063] The collector 12 is plate-shaped, for example made of copper, and is disposed on the inner surface of the cover plate 2, and has an insertion hole 120 for inserting the end of the shaft portion 81. The collector 12 has a joint portion 121 protruding outward from other portions at the center of the cover plate 2 and joined to the negative electrode tab 15.

[0064] The electrode body 13 is a stacked type including a main body 130 formed by alternately stacking a plurality of positive and negative metal plates with separators interposed therebetween to form a rectangular parallelepiped, and positive and negative electrode tabs 14 and 15 extending from the main body 130 to the cover plate 2 .

[0065] The electrode body 13 may be one obtained by winding a positive electrode metal plate and a negative electrode metal plate into a flat shape with a separator interposed therebetween.

[0066] The positive electrode metal plate is made of, for example, aluminum, and has a strip-shaped or rectangular plate-shaped metal foil and a positive electrode active material layer formed on the metal foil.

[0067] The positive electrode active material is lithium metal oxide. The positive electrode active material may also be a two-phase coexistence reaction type active material. Specifically, the positive electrode active material is a substance represented by the general formula LiMPO4, and M may also be any one of Fe, Mn, Cr, Co, Ni, V, Mo, and Mg.

[0068] The positive electrode active material may also be a polyanion compound (LiaFebPO4, LiaMnbPO4, LiaMnbSiO4, LiaCobPO4F, etc.) represented by LixMeOp (Me represents one or more transition metals, and X represents P, Si, B, V, etc.) containing a two-phase coexistence reaction type. The positive electrode active material may also be a composite oxide (LixCoO2, LixNiO2, LixMNo4, LixNiyMnzCo(1-y-z)O2, etc.) represented by LixMeOp (Me represents one or more transition metals).

[0069] The negative electrode metal plate is made of, for example, copper, and has a strip-shaped or rectangular plate-shaped metal foil and a negative electrode active material layer formed on the metal foil.

[0070] The negative electrode active material is a carbon material. Specifically, the negative electrode active material may be any one of graphite, graphitizable carbon, and non-graphitizable carbon.

[0071] For example, power storage device 30 of an HEV vehicle or an EV vehicle driven by an engine and a motor is provided with the degradation amount estimating device of the present embodiment.

[0072] Figure 3 2 is a block diagram of the power storage device 30 .

[0073] The power storage device 30 includes a plurality of batteries 1, a BMU (Battery Management Unit) 31, and a current sensor 39. The BMU 31 includes an information processing unit 32 having a CPU 33 and a memory 34, a voltage measuring unit 35, and a current measuring unit 36. The BMU 31 corresponds to the degradation amount estimating device of the present embodiment.

[0074] Various programs 34a including the estimation program of the continuous degradation amount, the estimation program of the transient degradation amount, and the control program of the transient degradation amount, and tables 34b are stored in the memory 34. The table 34b stores sampled current values, voltage values, estimated continuous degradation amounts, and transient degradation amounts.

[0075] The CPU 33 executes a process of estimating the amount of continuous degradation and the amount of transient degradation and a process of controlling the amount of transient degradation, which will be described later, based on the program 34 a read out from the memory 34 .

[0076] The voltage measuring unit 35 is connected to both ends of the battery 1 via voltage detection lines, and measures the voltage value of each battery 1 at predetermined time intervals.

[0077] The current measuring unit 36 ​​measures the value of the current flowing through the battery 1 at predetermined time intervals via the current sensor 39 .

[0078] An external terminal (not shown) of the power storage device 30 is connected to a load 38 such as a starter motor and electrical components for starting the engine.

[0079] The BMU 31 and the load 38 are connected to an ECU (Electronic Control Unit) 37 .

[0080] The degradation of battery 1 includes transient degradation and continuous degradation. If the transient degradation amount increases, continuous degradation that cannot be recovered will occur even if battery 1 is in a low-load state. The low-load state refers to a state where a low current flows that does not affect transient degradation, and also includes a state with no current, and can also be a no-load state after the ignition is turned off (IG-off). The vehicle starts the system by turning on the ignition (IG-on) to supply power to various parts of the vehicle, and stops the system by turning off the IG-off to stop the power supply.

[0081] Transient degradation is a decrease in output performance that can be recovered. It is a transient degradation phenomenon caused by depletion of the electrolyte in the electrode due to ion segregation in the electrolyte during charge and discharge.

[0082] When the battery 1 is charged, if the potential of the negative electrode active material layer of the electrode body 13 is lower than the precipitation potential, metal precipitation occurs in the negative electrode active material layer and the degradation of the battery 1 progresses rapidly. The potential and precipitation potential of the negative electrode active material layer of the electrode body 13 change according to the charging state of the battery 1, the charging time of the battery 1, the current input to the battery 1, the temperature of the battery 1, etc. In a usage environment where a large current flows into the battery 1, metal precipitation is likely to occur in the negative electrode active material layer. In a low temperature environment (below 25°C, especially below 0°C), metal precipitation is likely to occur in the negative electrode active material layer. When the charging state of the battery 1 is high (SOC 50% or more), metal precipitation is likely to occur in the negative electrode active material layer. The degradation caused by the above metal precipitation also corresponds to transient degradation.

[0083] Localized degradation of electrodes and electrolytes caused by transient degradation affects sustained degradation.

[0084] Figure 4 This is a graph showing the relationship between IG-on and IG-off and changes in output performance.

[0085] like Figure 4 As shown in FIG. 1 , after IG-on, the output performance decreases compared to the initial output performance by adding a load to the storage element. By performing IG-off and setting the storage element to a no-load state, the output performance recovers. Figure 4 The time t i For a greatly reduced output, if the IG-off period (the reduction time described later) is sufficiently long, the recovery amount (the increase in output) converges to approximately 0. a The output performance reduction that remains without recovery is equivalent to continuous degradation. After estimating the continuous degradation amount, during the period when the continuous degradation does not increase (t b and t a The difference between the degradation amount (output performance reduction rate) at a certain time (calculation time) and the continuous degradation amount is equivalent to the transient degradation amount. The description is given in terms of IG-on state or IG-off state, but the low load state may be substituted for the IG-off state.

[0086] In this embodiment, the degradation amount is quantified based on the internal resistance value. The decrease in output performance occurs due to an increase in the internal resistance value.

[0087] The internal resistance value is obtained by calculating the slope of the I-V characteristic of the current value I and the voltage value V stored in Table 34b by the least square method. The calculation of the internal resistance value is greatly affected by the SOC and temperature, so it is preferably corrected to the value at the same SOC and temperature. In order to improve the accuracy of the calculation of the internal resistance value, it is considered to shorten the sampling interval of the current value I and the voltage value V, multiply the forgetting coefficient, or change the weighting of each parameter.

[0088] The degradation amount (calculated degradation amount) is calculated by the following formula.

[0089] Degradation amount = (current internal resistance value) - (initial internal resistance value)

[0090] The initial internal resistance value may be the internal resistance value when the vehicle is first driven immediately after the battery 1 is mounted on the vehicle. The initial internal resistance value may also be obtained by passing a current through the battery 1 after the battery 1 is manufactured.

[0091] Figure 5 This is a graph showing the relationship between the time elapsed from immediately after the battery 1 is mounted on the vehicle and the internal resistance value. The horizontal axis represents the time elapsed, and the vertical axis represents the resistance value (internal resistance value: Ω).

[0092] When the battery 1 is installed in the vehicle and IG-ON is performed and the vehicle starts to drive, Figure 5 As shown in FIG. 1 , the internal resistance value increases. The internal resistance value at the start time t0 of driving is the initial value R0. This is just after the battery 1 is mounted on the vehicle, and no continuous degradation occurs in the battery 1.

[0093] The difference between the internal resistance value at a certain time after the start of running and the initial value R0 corresponds to the amount of transient degradation.

[0094] The transient degradation amount at time t1 is represented by the difference ( R1 − R0 ) between the internal resistance values ​​R1 and R0 .

[0095] The transient degradation amount at time t2 is represented by the difference between the internal resistance values ​​R2 and R0 ( R2 − R0 ).

[0096] When IG-off is performed at time t2, the amount of increase in resistance decreases.

[0097] exist Figure 5 In FIG. 1 , the dotted line indicates a decrease in resistance value. However, during the IG-off period, since the resistance value cannot be obtained, the diagram is shown as a conceptual diagram.

[0098] Figure 6 This is a graph showing the relationship between the elapsed time and the internal resistance value when IG-off, IG-on, IG-off, and IG-on are repeated. The horizontal axis is the elapsed time, and the vertical axis is the resistance (internal resistance value: Ω).

[0099] After the second IG-off at time t3, the internal resistance value decreases, and the decrease converges to approximately 0 at time t4. That is, the transient degradation disappears at this time. At time t4, the difference (R0′-R0) between the internal resistance values ​​R0′ and R0 obtained when IG-on is performed is equivalent to the continuous degradation amount. Then, the internal resistance value is increased by IG-on, and the difference (R3-R0′) between the internal resistance values ​​R3 and R0′ calculated at time t5 is equivalent to the transient degradation amount. The transient degradation amount is the difference between the degradation amount (R3-R0) at time t5 and the continuous degradation amount.

[0100] The time between time t4 and time t3 is defined as the falling time.

[0101] Figure 7 This is a graph showing the relationship between the elapsed time and the internal resistance value when the continuous degradation amount is quantified and IG-off, IG-on, and IG-off are repeated. The horizontal axis is the elapsed time, and the vertical axis is the resistance value (internal resistance value: Ω).

[0102] The amount of continuous degradation is Figure 7 The (R0′-R0) was quantified in the experiment.

[0103] The transient degradation amount at time t6 is represented by the difference between the internal resistance values ​​R4 and R0' (R4-R0').

[0104] The transient degradation amount at time t7 is represented by the difference (R5-R0') between the internal resistance values ​​R5 and R0'.

[0105] The transient degradation amount at time t8 is represented by the difference between the internal resistance values ​​R6 and R0' (R6-R0').

[0106] The fall time is preferably the time required for the transient degradation amount to completely disappear.

[0107] However, it is sometimes unrealistic to maintain the no-load state until the transient degradation amount completely disappears.

[0108] Therefore, the fall time can be approximated in the following manner.

[0109] Approximately 90% of car users travel a distance of 50 km or less per day. Assuming an average speed of 30 km per hour, the travel time can be estimated to be 1.5 hours or less.

[0110] In a car designed to be susceptible to transient degradation, transient degradation of 2% (increase rate of internal resistance) occurs at 25°C for 14 hours of driving. If the driving time is 1.5 hours, transient degradation of 0.2% is considered to occur.

[0111] The time interval (cycle time) from IG-on to IG-off was set to 14 hours, and the driving test was performed for 1.5 hours to investigate the relationship between the storage time after IG-off and the amount of transient degradation. The results are shown in Figure 8 The horizontal axis is the storage time (h), and the vertical axis is the transient degradation amount (%). Figure 8 In the figure, ◇ indicates that the cycle time is 1.5 hours and the amount of transient degradation just after the cycle is 0.2%, and □ indicates that the cycle time is 14 hours and the amount of transient degradation just after the cycle is 2%.

[0112] like Figure 8 As shown, after 24 hours, the transient degradation amount was reduced to 0.1%, and the transient degradation amount and the continuous degradation amount could be quantified with an accuracy within 0.1%.

[0113] In this case, the CPU 33 (setting unit) sets the approximate decline time to 24 hours. The continuous degradation amount may be obtained by subtracting 0.1% from the degradation amount calculated after 24 hours have passed.

[0114] Similarly, the CPU 33 can obtain the approximate fall time through calculation based on the relationship between the idle time after IG-off and the transient degradation amount. The calculation formula is as follows.

[0115] y=A·exp(-x / τ)

[0116] Where, y: temporary degradation

[0117] x: time

[0118] A: Correction coefficient

[0119] τ: time constant

[0120] CPU33 investigates the relationship between the standing time after IG-off and the amount of transient degradation under multiple charging and discharging conditions, and pre-calculates a table or function that associates the charging and discharging conditions (usage conditions) with the standing time and the amount of transient degradation. Based on the currently acquired charging and discharging conditions, and by referring to the table or using the function, the approximate decline time can be calculated.

[0121] The estimation process of the continuous degradation amount by the CPU 33 will be described.

[0122] Fig. 9 2 is a flowchart showing the processing procedure of estimating the continuous degradation amount by the CPU 33. The CPU 33 performs this processing when a predetermined period D has elapsed.

[0123] The prescribed period D is the number of days during which continuous degradation occurs. The rate of increase of the internal resistance value is less than 0.01% / day. When the threshold value of the control of transient degradation described later is set to 2%, and the estimated error of the transient degradation amount is allowed to be 10% of the threshold value (transient degradation amount 0.2%), the transient degradation amount can be estimated after estimating the continuous degradation amount during 20 days. In this case, D is 20 days. That is, D is set based on the rate of increase of the internal resistance value of the battery 1 per day, the allowable estimated error of the transient degradation amount, etc.

[0124] The CPU 33 first determines whether the current flowing through the load is less than or equal to a threshold value A (A: ampere) (S1). If the CPU 33 determines that the current flowing through the load is not less than or equal to the threshold value A (A) (S1: No), the CPU 33 repeats the determination process.

[0125] When the CPU 33 determines that the current flowing through the load is less than the threshold value A (A) (S1: Yes), it determines whether the falling time has passed (S2). The falling time may be the time when the transient degradation amount completely disappears, or it may be an approximate falling time. When the CPU 33 determines that the falling time has not passed (S2: No), it repeats the determination process.

[0126] If it is determined that the falling time has elapsed (S2: YES), the CPU 33 determines whether the current flowing through the load is larger than the threshold value A (A) (S3). If it is determined that the current flowing through the load is not larger than the threshold value A (A) (S3: NO), the CPU 33 repeats the determination process.

[0127] When the CPU 33 determines that the current flowing through the load is greater than the threshold value A (A) (S3: Yes), it calculates the resistance value (S4). Figure 6 As shown in FIG. 1 , the CPU 33 calculates the internal resistance value R0 ′ based on the current value and the voltage value acquired at the time when the current flowing through the load becomes larger than the threshold value A.

[0128] CPU 33 estimates the continuous degradation amount based on R0′-R0 (S5). The falling time is an approximate falling time. Figure 8 As shown, the convergence value of the drop amount when the approximate drop time is known (the residual transient degradation amount, in Figure 8 In the case of 0.1% in the example above, the continuous degradation amount is a value obtained by subtracting the convergence value from the degradation amount at the time when the approximate falling time has passed.

[0129] The CPU 33 stores the continuous degradation amount in the table 34b (S6).

[0130] Fig.10This is a flowchart showing the processing procedure of estimating the transient degradation amount and controlling the transient degradation by the CPU 33. The CPU 33 performs the following processing at appropriate intervals or at arbitrary timing.

[0131] The CPU 33 determines whether the current flowing through the load is larger than the threshold value A (A) ( S11 ). When the CPU 33 determines that the current flowing through the load is not larger than the threshold value A (A) ( S11 : No), the CPU 33 repeats the determination process.

[0132] When the CPU 33 determines that the current flowing through the load is larger than the threshold value A (A) ( S11 : Yes), it calculates the internal resistance value ( S12 ).

[0133] The CPU 33 calculates the degradation amount based on the internal resistance value (S13). Figure 7 As shown in the figure, (internal resistance value - initial value) is the amount of degradation.

[0134] The CPU 33 estimates the transient degradation amount based on the difference between the calculated degradation amount and the continuous degradation amount ( S14 ).

[0135] The CPU 33 determines whether the transient degradation amount is a% or more (S15).

[0136] When the CPU 33 determines that the transient degradation amount is a% or more ( S15 : Yes), the CPU 33 performs the first control ( S16 ) and ends the processing.

[0137] When the CPU 33 determines that the transient degradation amount is not greater than a% (S15: No), it determines whether the transient degradation amount is greater than b% and less than a% (S17). When the CPU 33 determines that the transient degradation amount is greater than b% and less than a% (S17: Yes), it performs the second control (S18) and ends the process.

[0138] When the CPU 33 determines that the transient degradation amount is not greater than b% and less than a% ( S17 : NO), the CPU 33 performs the third control ( S19 ) and ends the processing.

[0139] As specific numerical values ​​of a% and b%, 5% and 2% are given.

[0140] When the transient degradation is 5% or more, the maximum load is adjusted by changing the current value input and output in the battery 1 in the first control. The utilization rate of the battery 1 is actively reduced and the utilization rate of the engine is increased. As the application objects of the battery 1 in the first control, auxiliary systems such as electric stabilizers, defoggers, sensors for driving assistance systems and automatic driving, communication devices (automatic braking, coasting), anti-theft devices, keyless entry, and electrical components such as interior lights can be cited.

[0141] The first control suppresses shortening of the life of the battery 1 and metal deposition in the negative electrode active material layer.

[0142] When the transient degradation amount is 2% or more and less than 5%, use of some batteries 1 is restricted as the second control.

[0143] As the application objects of the battery 1, in the case of auxiliary systems, there can be cited auxiliary systems such as air conditioners, electric stabilizers, defoggers, sensors for driving assistance systems and automatic driving, communication devices (automatic braking, coasting), immobilizers, keyless entry, and electrical components such as interior lights. In the case of drive systems, there can be cited auxiliary loads during battery idle stop and restart, regeneration during deceleration, electric turbochargers, and low-speed EV driving (parking, traffic jams), etc.

[0144] The second control suppresses shortening of the life of the battery 1 and metal deposition in the negative electrode active material layer.

[0145] When the transient degradation amount is less than 2%, the usage rate of the battery 1 is actively increased only for a short period of time as the third control.

[0146] As the application objects of the battery 1, in the case of auxiliary systems, there are air conditioners, electric stabilizers, defoggers, sensors for driving assistance systems and automatic driving, communication devices (automatic braking, coasting), immobilizers, keyless entry, interior lights and other electrical components. In the case of drive systems, there are EV driving, starting, auxiliary loads during battery idle stop and restart, regeneration during deceleration, electric power assist (motor assist), electric turbochargers, low-speed EV driving (parking, traffic jams), etc.

[0147] The third control improves the combustion performance and the power performance, and suppresses the metal precipitation in the negative electrode active material layer.

[0148] As described above, in the present embodiment, the amount of continuous degradation can be estimated well based on the amount of degradation calculated when the drop time has elapsed, and the internal state of the battery 1 can be grasped well.

[0149] By estimating the transient degradation amount (quantifying it) based on the calculated degradation amount and the sustained degradation amount, limiting the application of the battery 1 and performing input / output restrictions, it is possible to effectively suppress an increase in the sustained degradation amount. Thus, shortening of the life of the battery 1 is suppressed.

[0150] Since the continuous degradation amount increases over a long period of time, the transient degradation amount can be estimated with high accuracy by updating the continuous degradation amount when a predetermined period of time has elapsed.

[0151] By approximately setting the decrease time based on the usage conditions of the battery 1 and a predetermined convergence value of the decrease amount, the transient degradation amount can be estimated realistically and accurately.

[0152] (Second Embodiment)

[0153] In the CPU 33 of the second embodiment, when the continuous degradation amount is not estimated within C days and when the continuous degradation amount is not updated within D days, the transient degradation amount is estimated by another method.

[0154] Fig.11 This is a flowchart showing the processing procedure of estimating the transient degradation amount and controlling the transient degradation by the CPU 33. The CPU 33 executes the following processing at predetermined intervals or at an arbitrary timing.

[0155] The CPU 33 detects the current value ( S21 ).

[0156] The CPU 33 calculates the SOC of the battery 1 based on the detected current value ( S22 ).

[0157] The CPU 33 determines whether the continuous degradation amount is estimated within C days (S23). For example, 30 days are taken as C days.

[0158] When the CPU 33 determines that the continuous degradation amount has not been estimated within C days ( S23 : NO), the process proceeds to S25 .

[0159] When the CPU 33 determines that the amount of continuous degradation is estimated within C days (S23: YES), after estimating the amount of continuous degradation, it determines whether it is within D days (S24). Here, for example, 20 days can be cited as D days.

[0160] After estimating the continuous degradation amount, if the CPU 33 determines that the time is not within D days ( S24 : NO), the process proceeds to S25 .

[0161] The CPU 33 detects the temperature of the battery 1 in S25 ( S25 ).

[0162] The CPU 33 calculates the average load, the maximum load, and ΔSOC based on the detected current value and temperature ( S26 ).

[0163] The average load refers to an average current value (time average value of charging current and discharging current) in the time interval from the IG-on time to the time when the transient degradation amount of the battery 1 is estimated, and is reset to a value when the IG is off.

[0164] The maximum load refers to the maximum current value in the time interval from the IG-on time to the time when the transient degradation amount of the battery 1 is estimated when the battery 1 is mounted on the vehicle, and is reset to the value when the IG-off time is reached.

[0165] ΔSOC refers to the difference between the maximum SOC and the minimum SOC in the time interval from the IG-on time to the time when the transient degradation amount of the battery 1 is estimated, and is reset to a value when the IG is off.

[0166] The CPU 33 estimates the transient degradation amount using a table or calculation ( S27 ).

[0167] In S27, the transient degradation amount is expressed not by the increase in the internal resistance value but by the decrease (%) in the output performance.

[0168] The table 34b stores a first table, a second table, and a third table.

[0169] The first table is data in which the average load of the battery 1, the temperature of the battery 1, and the transient degradation amount of the battery 1 corresponding to each value of the average load and temperature are associated. The second table is data in which the maximum load of the battery 1, the temperature of the battery 1, and the transient degradation amount of the battery 1 corresponding to each value of the maximum load and temperature are associated. The third table is data in which ΔSOC, the temperature of the battery 1, and the transient degradation amount of the battery 1 corresponding to each value of ΔSOC and temperature are associated.

[0170] CPU 33 refers to the first table, the second table, and the third table to obtain the first, second, and third transient degradation amounts corresponding to the obtained average load, maximum load, ΔSOC, and detected temperature, and estimates the transient degradation amount based on these total values.

[0171] Alternatively, the CPU 33 estimates the transient degradation amount using the following equation.

[0172] D=α(T)·A+β(T)·B+γ(T)·C-K(T)·E+Dstop

[0173] Here, A is the maximum load, B is the average load, C is ΔSOC, E is the stop time (time interval from IG-on to IG-off), and T is the temperature of battery 1. α(T) is a coefficient about the maximum load, β(T) is a coefficient about the average load, and γ(T) is a coefficient about ΔSOC. α(T), β(T), and γ(T) are coefficients whose values ​​increase as the time interval (cycle time) from IG-on to IG-off increases. K(T) is a mitigation coefficient, and Dstop is the value of the transient degradation amount just before the vehicle stops.

[0174] After estimating the transient degradation amount, the CPU 33 proceeds to S29 .

[0175] After estimating the continuous degradation amount, when the CPU 33 determines that the time is within D days (S24: Yes), it estimates the transient degradation amount in the same manner as in the first embodiment (S28).

[0176] In S29 , the CPU 33 determines whether the transient degradation amount is equal to or less than a threshold value.

[0177] When the CPU 33 determines that the transient degradation amount is not less than the threshold value ( S29 : No), the CPU 33 changes the current value input to and output from the battery 1 to a value set in advance, thereby adjusting the maximum load, for example ( S30 ).

[0178] When the CPU 33 determines that the transient degradation amount is equal to or smaller than the threshold value ( S29 : Yes), the CPU 33 ends the processing.

[0179] As in the first embodiment, a plurality of the above-mentioned threshold values ​​may be set, and a plurality of transient degradation amount controls may be set, and control corresponding to the relationship between the transient degradation amount and each threshold value may be performed.

[0180] In the present embodiment, when the continuous degradation amount is updated within C days, if the decline time or the approximate decline time cannot be ensured during IG-off and the continuous degradation amount cannot be updated, or if D days have passed after the update, the transient degradation amount is estimated by other methods. In the above case, the transient degradation amount is estimated by this method, and when the continuous degradation amount can be updated, the transient degradation amount is estimated based on the calculated degradation amount and the continuous degradation amount, so the transient degradation amount can always be estimated with good accuracy.

[0181] The degradation amount estimating device, the power storage device, and the degradation amount estimating method of the present invention are not limited to the first and second embodiments, and various modifications may be added without departing from the spirit of the present invention.

[0182] The storage element of the first embodiment and the second embodiment is a non-aqueous electrolyte secondary battery, specifically a lithium-ion battery, but the storage element is not limited to a lithium-ion secondary battery. The storage element may also be a battery or capacitor other than a lithium-ion secondary battery that produces the same transient degradation as a lithium-ion secondary battery. The storage element can be any element that produces transient degradation, and its use is not limited to vehicle-mounted use. In the embodiment, as an example of determining whether it is a low-load state when the storage element is mounted on a vehicle, it is determined whether it is an IG-on state (loaded state) or an IG-off state (unloaded state). In other uses, the threshold value of the current value can also be used for judgment.

[0183] The threshold value of the transient degradation amount is also not limited to the value in the embodiment.

[0184] In the first embodiment and the second embodiment, the case where the BMU 31 is the degradation amount estimating device has been described, but the ECU 37 may also be the degradation amount estimating device.

[0185] The power storage system of the present invention is not limited to the above-mentioned power storage device 30. A degradation amount estimation device and / or a regulating unit may be provided outside the power storage device. The power storage system is not limited to being mounted on an HEV or EV, but may be mounted on a PHEV. It is not limited to being mounted on a vehicle, but may be mounted on a moving object such as a train, a ship, or an aircraft, and is not limited to being mounted on a moving object.

[0186] The present invention can also be applied to a mobile body with two power sources. For example, in the case of a vehicle, an AC generator, a starter motor, a lead-acid battery (auxiliary storage element or auxiliary storage device) as a 12V power source, and a lithium-ion secondary battery as a 12V power source or a 48V power source are sometimes carried. During the period when the current output and input in the lithium-ion secondary battery is adjusted in such a way that the estimated value of the transient degradation amount of the lithium-ion secondary battery becomes less than the specified value, the power is supplied to the load (such as an auxiliary machine) through the lead-acid battery. Alternatively, the power from the lead-acid battery can also be supplied to the load (such as an auxiliary machine) preferentially. In the case of a vehicle with two power sources, it is considered to be a high load compared to the case of one power source due to low combustion and high functionality and electrification of vehicle components. In the case of two power sources, the transient degradation of the lithium-ion secondary battery is greatly affected by capacity, output performance, and especially long-term output. In a low temperature environment, transient degradation is easily generated in the lithium-ion secondary battery, and the control method of the present invention is beneficial. The auxiliary storage element (or auxiliary storage device) is not limited to a lead-acid battery, and can be other batteries or a capacitor.

[0187] Description of the attached drawings

[0188] 1Battery (storage element)

[0189] 2 Cover

[0190] 3 Shell body

[0191] 4 Positive terminal

[0192] 8 Negative terminal

[0193] 5.9 Insulation board

[0194] 6.10 Sealing gasket

[0195] 11 Shell

[0196] 7.12 collector

[0197] 13 Electrode body

[0198] 14 positive pole ear

[0199] 15 negative electrode tab

[0200] 30Electrical storage device

[0201] 31BMU (Deterioration Amount Estimation Unit)

[0202] 32 Information Processing Department

[0203] 33CPU (calculating unit, first calculating unit, second calculating unit, estimating unit, first estimating unit, second estimating unit, setting unit, adjusting unit)

[0204] 34 Memory

[0205] 34a Procedure

[0206] Table 34b

[0207] 35 Voltage measurement unit

[0208] 36 Current measurement unit

[0209] 37ECU

[0210] 38 Load

[0211] 39 Current sensor

Claims

1. A degradation amount estimation device, characterized in that: have: a calculation unit that calculates a degradation amount of the power storage element; an estimating unit that estimates a transient degradation amount based on the degradation amount and a continuous degradation amount that does not decrease with the passage of time but continues, The continuous degradation amount is estimated based on the degradation amount calculated by the calculation unit at a predetermined time. The predetermined time is a time when the degradation amount is calculated to decrease when the load is smaller than the predetermined value and an approximate decrease time at which the decrease amount converges has passed. The approximate fall time is set based on the relationship between the standing time and the transient degradation amount.

2. A degradation amount estimation device, characterized in that: have: a first calculation unit that calculates a calculated degradation amount of the power storage element; a first estimating unit that estimates a transient degradation amount based on the calculated degradation amount at the calculation time and the calculated degradation amount at a predetermined time, The predetermined time is a time when the calculated degradation amount decreases when the load is smaller than the predetermined value and an approximate decrease time at which the calculated degradation amount decrease converges has elapsed. The approximate fall time is set based on the relationship between the standing time and the transient degradation amount.

3. The degradation amount estimating device according to claim 2, characterized in that: have: a second calculation unit for calculating an internal resistance value of the power storage element, The first calculation unit calculates the degradation amount based on the internal resistance value calculated by the second calculation unit.

4. The degradation amount estimating device according to claim 2 or 3, characterized in that: The degradation amount estimating device includes a second estimating unit that estimates a continuous degradation amount based on the calculated degradation amount calculated by the first calculating unit at the time point, The first estimating unit estimates the transient degradation amount based on the calculated degradation amount at the calculation time and the continuous degradation amount.

5. The degradation amount estimating device according to claim 4, characterized in that: The second estimating unit estimates the amount of continuous degradation when a predetermined period has elapsed and the load is smaller than the predetermined value, wherein the predetermined period is the number of days during which continuous degradation occurs.

6. The degradation amount estimating device according to claim 4, characterized in that: A setting unit is provided for setting the approximate decrease time according to a predetermined convergence value of the decrease amount based on the relationship between the storage time and the transient degradation amount under the use condition of the power storage element.

7. A power storage system, characterized in that: have: Storage element; The degradation amount estimating device according to any one of claims 1 to 6; The regulator adjusts the amount of current inputted or outputted to the power storage element so that the amount of transient degradation of the power storage element becomes equal to or less than a predetermined value.

8. A degradation amount estimation device, characterized in that: have: a calculation unit that calculates a degradation amount of the power storage element; An estimating unit estimates a continuous degradation amount based on the degradation amount calculated by the calculating unit when the degradation amount decreases when the load of the power storage element is smaller than a predetermined value and an approximate decrease time for the decrease amount to converge has passed, wherein the approximate decrease time is set based on a relationship between an unused time and a transient degradation amount.

9. A method for estimating a degradation amount, characterized in that: Calculate the degradation amount of the storage element, Based on the calculated degradation amount and the continuous degradation amount that does not decrease over time but continues, the transient degradation amount is estimated. The continuous degradation amount is estimated based on the degradation amount calculated at a predetermined time. The predetermined time is a time when the degradation amount is calculated to decrease when the load is smaller than a predetermined value and an approximate decrease time at which the decrease amount converges has elapsed, and the approximate decrease time is set based on the relationship between the idle time and the transient degradation amount.

10. A method for estimating a degradation amount, characterized in that: Calculate the calculated degradation amount of the storage element, Based on the calculated degradation amount at the calculation time and the calculated degradation amount at the predetermined time, the transient degradation amount is estimated. The predetermined time is a time when the calculated degradation amount decreases when the load is smaller than a predetermined value and an approximate decrease time for the calculated degradation amount to converge has elapsed, and the approximate decrease time is set based on the relationship between the idle time and the transient degradation amount.

11. A computer program product comprising a computer program, characterized in that When the computer program is executed, the following processing is implemented: Calculate the degradation amount of the storage element, Based on the calculated degradation amount and the continuous degradation amount that does not decrease over time but continues, the transient degradation amount is estimated. The continuous degradation amount is estimated based on the degradation amount calculated at a predetermined time. The predetermined time is a time when the degradation amount is calculated to decrease when the load is smaller than a predetermined value and an approximate decrease time at which the decrease amount converges has elapsed, and the approximate decrease time is set based on the relationship between the idle time and the transient degradation amount.

12. A computer program product comprising a computer program, characterized in that When the computer program is executed, the following processing is implemented: Calculate the calculated degradation amount of the storage element, Based on the calculated degradation amount at the calculation time and the calculated degradation amount at the predetermined time, the transient degradation amount is estimated. The predetermined time is a time when the calculated degradation amount decreases when the load is smaller than the predetermined value and an approximate decrease time at which the calculated degradation amount decrease converges has elapsed. The approximate fall time is set based on the relationship between the standing time and the transient degradation amount.

Images