Method for controlling charge and discharge of secondary battery

Abstract

To correct an SOC use range according to an SOC estimation error rapidly and easily and control charge and discharge safely and efficiently.SOLUTION: A controller estimates an estimation voltage VE[V] (S2) on the basis of a measured current AM [A], a measured voltage VM[V], and a measured temperature TM[°C] of a lithium ion secondary battery (S1), collects a sample for calculating an estimated error E[%] of an SOC (S5), and calculates the upper limit error EH[%] and the lower error EL[%] (S8). Also, the controller resets the upper limit LH of a use SOC from the upper limit error EH[%] and resets the lower limit LL of a use SCO from the lower limit error EL (S10). The controller further controls discharge and charge of the lithium ion secondary battery on the basis of a usable SOC range after correction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for controlling charge and discharge of a secondary battery, and more particularly to a method for controlling charge and discharge of a secondary battery that safely and efficiently controls the SOC usage range according to the SOC estimation error.

Background Art

[0002] In secondary batteries, particularly in drive secondary batteries mounted in electric vehicles and hybrid vehicles, charge and discharge are performed with a large current during rapid acceleration, regenerative current due to braking, rapid charging, etc. In order to avoid over-discharge and over-charging for such charge and discharge, control is performed to limit the usage range of SOC (State Of Charge). For example, the upper limit value for use is set to 80 [%] and the lower limit value is set to 20 [%], and charge and discharge control is always performed so that the SOC is within this range.

[0003] For example, the invention described in Patent Document 1 describes an invention that limits the charge and discharge rate according to the SOC. However, when there is an error in the calculation of the SOC, the range of the SOC appropriate for use also changes, but the invention described in Patent Document 1 does not correct the SOC usage range itself.

[0004] In order to control more safely and efficiently for such control, the following inventions have been proposed. For example, in the invention described in Patent Document 2, the SOC based on the current integration value is obtained as the true value, and the error of the estimated SOC with respect to it is calculated. By this, the SOC upper and lower limits are corrected. With such an invention, more appropriate control can be achieved.

[0005] In the invention described in Patent Document 3, the parameters of the battery model are obtained through a neural network. Then, the parameters of the battery model are repeatedly updated according to the difference between the output value of the battery model reflecting the obtained parameters and the actually measured value. By doing so, a battery model optimized for the battery cell can be constructed, and the charging of the battery can be controlled based on the optimized battery model. With such an invention, more appropriate control can be achieved.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the invention described in Patent Document 2, there is a problem that it takes time to obtain the error in order to use the current integration as the true value of the SOC estimation. Also, regarding the current integration value, there is an error in the current measurement itself, and there is a problem that it is easily affected by the accumulation of errors during long-term acquisition.

[0008] In addition, in the invention described in Patent Document 3, regarding the correction method, since the battery model itself is updated each time, there is a problem that the battery model cannot be separated from the limit. Also, immediately after the start of battery use, since the model has not been corrected, there is a problem that it is impossible to use the battery taking into account the error.

[0009] The problem of the method for controlling charging and discharging of the secondary battery of the present invention is to quickly correct the SOC usage range according to the SOC estimation error by a simple method and control charging and discharging safely and efficiently.

Means for Solving the Problem

[0010] To solve the above problems, a method for controlling charging and discharging of a secondary battery according to the present invention is a method for controlling charging and discharging of a secondary battery by a control device. The control device measures the secondary battery to obtain a measured current A M [A], a measured voltage V M [V], and a measured temperature T M [°C] in an information acquisition step, and based on the measured current A M [A] and the measured temperature T M [°C] obtained in the information acquisition step, estimates an estimated voltage V E [V] in a battery voltage estimation step, and when a current I is flowing through the secondary battery under certain conditions, collects samples of the difference ΔV [V] between the measured voltage V M [V] for calculating the estimation error E [%] of SOC and the estimated voltage V E [V] in a sample collection step, and classifies the samples collected in the sample collection step into an upper limit determination sample SP H or a lower limit determination sample SP L in a sample classification step based on a reference value S [%] with respect to a preset normal SOC center, calculates an upper limit error E H [%] based on the upper limit determination sample SP H collected in a certain number or more, and a lower limit error E L [%] based on the lower limit determination sample SP L in an SOC estimation error calculation step, and resets an upper limit L H of the used SOC from the upper limit error E H [%], and a lower limit L L of the used SOC from the lower limit error E L in an upper and lower limit SOC reset step. The method is characterized by controlling the range of the used SOC of the secondary battery.

[0011] In the upper and lower limit SOC reset step, the upper limit L of the used SOC is reset based on the estimation error E [%] of SOC calculated in the SOC estimation error calculation step.H 1. Use the lower limit L of the SOC L 2. Implement a guard process to optimize the SOC range S that can be used based on the lower limit L U It is also preferable to include steps of the guard process for the upper and lower limits, which implement a guard process to optimize the SOC range S that can be used based on the lower limit L of the SOC.

[0012] The steps of the guard process for the upper and lower limits are to control the settings of the upper limit L H and the lower limit L L so that the SOC range S that can be used based on the upper limit L U and the lower limit L H is 20% or more. L The settings of the upper limit L and the lower limit L may be controlled.

[0013] The steps of the guard process for the upper and lower limits are such that the upper limit L set from the upper limit error E H [%] is set within the range of the maximum difference ΔMax and the minimum difference ΔMin of the upper limit error E H [%], and the lower limit L set from the lower limit error E H [%] is set within the range of the maximum difference ΔMax and the minimum difference ΔMin of the lower limit error E L It may be set in this way. L The steps of the guard process for the upper and lower limits are such that the upper limit L set from the upper limit error E L It may be set within the range of the maximum difference ΔMax and the minimum difference ΔMin of the lower limit error E

[0014] In the step of estimating the battery voltage, the estimated voltage can be estimated as the voltage V E [V] which is the open-circuit voltage of the secondary battery by the battery model of the secondary battery set in advance. The measured voltage V M [V] and the estimated voltage V E [V] may be further included in the step of correcting the battery model by comparing them.

[0015] The step of correcting the battery model may be executed when the difference ΔV[V] between the measured voltage V M [V] and the estimated voltage V E [V] is equal to or greater than the threshold Th. In the step of the sample classification, a reference value S based on a preset common SOC center for classifying the collected sample into an upper limit determination sample or a lower limit determination sample may be set to a value of SOC 40[%] or more and SOC 60[%] or less.

[0016] In the step of calculating the SOC estimation error, when the estimation error of the SOC is E [%], the number of samples collected is N, the number of sample collection times is k, the measured voltage is V M [V], the estimated voltage is V E [V], and the voltage corresponding to 1[%] of the SOC of the secondary battery is V1 [V], the estimation error E [%] can be calculated by

[0017]

Number

[0018] . The secondary battery is a power source for driving a vehicle, and the control device can be preferably implemented when mounted on a vehicle. The secondary battery can be preferably implemented when it is a lithium-ion secondary battery.

Advantages of the Invention

[0019] According to the charge and discharge control method of the secondary battery of the present invention, the SOC usage range can be quickly corrected according to the SOC estimation error by a simple method, and the charge and discharge can be controlled safely and efficiently.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0021] (Outline of the present embodiment) Hereinafter, a method for controlling charge and discharge of a secondary battery of the present invention will be described with reference to FIGS. 1 to 7 by taking an example of a method for controlling charge and discharge of a lithium-ion secondary battery 1.

[0022] <Principle of the invention of the present embodiment> The method for controlling charge and discharge of the lithium-ion secondary battery 1 of the present embodiment quickly corrects the SOC usage range according to the SOC estimation error by a simple method, and controls charge and discharge safely and efficiently. As described in the background art, conventionally, there has been a problem that it takes time to obtain an error in order to use current integration as the true value of SOC estimation as in the invention described in Patent Document 2. In addition, regarding the current integration value, there is an error in the measurement of the current itself, and there is a problem that it is easily affected by the accumulation of errors during long-term acquisition. In addition, regarding the correction method as in the invention described in Patent Document 3, since the battery model itself is updated each time, there is a problem that the battery model cannot be separated from the limit. In addition, immediately after the start of battery use, since the model has not been corrected, there is a problem that it is impossible to use it taking into account the error.

[0023] Therefore, in the charge and discharge control method of the lithium-ion secondary battery 1 of the present embodiment, by estimating the SOC based on voltage, which has less measurement error and a shorter measurement time than the estimation of SOC by current integration, the error of the SOC can be detected quickly and in real time. Further, by appropriately correcting the battery model, the accuracy of the SOC estimation can be improved. By detecting the SOC error quickly and accurately in this way, even for a battery with a usage history, by setting an appropriate SOC usage range, deterioration can be suppressed while fully exerting the performance of the battery.

[0024] <Estimation of SOC [%] in the present embodiment> FIG. 1 is a diagram for explaining the control of the SOC in the present embodiment. In the lithium-ion secondary battery 1 of the present embodiment, in the initial stage, SOC0 [%] to SOC100 [%] are set, and the battery model of the lithium-ion secondary battery 1 designed in this way is assumed.

[0025] FIG. 2 is a diagram showing an equivalent circuit of the battery model of the lithium-ion secondary battery 1 of the present embodiment. The lithium-ion secondary battery 1 can be shown as an equivalent circuit by a register R0 and a parallel circuit of a register R1 and a capacitor C1 connected in series thereto as shown in FIG. 2. Such an equivalent circuit can specify the values of the register (resistance) R0, the register R1, and the capacitor C1, for example, by complex alternating current impedance measurement. And the combined resistance of the whole equivalent circuit can be obtained. There are various factors in the state change of the actual lithium-ion secondary battery 1. For example, there are factors such as an increase in internal resistance due to the formation of a film such as SEI (Solid Electrolyte Interphase) on the negative electrode, decomposition of the non-aqueous electrolyte, self-discharge due to a micro short circuit, and a temporary ion bias. However, for the sake of simple SOC prediction, these are simplified and can be represented by an equivalent circuit with a register (resistance) R0, R 1、 and a capacitor (capacitance) C1. With such a battery model, based on the information of the measured current A M [A] and the measured temperature T M [°C], the estimated voltage V E[V] can be estimated. Since the internal resistance changes with temperature, temperature correction is required. Note that the battery model is not invariant and correction due to deterioration is required.

[0026] Next, in the battery model configured as described above, SOC [%] can be estimated based on the open-circuit battery voltage OCV (Open Circuit Voltage). However, in this embodiment, since the voltage between both terminals of the battery is measured while the battery is connected to the device and current is flowing, the closed-circuit voltage CCV (Closed Circuit Voltage) will be measured. Since the battery has an internal resistance, the closed-circuit voltage shows a value smaller than the circuit voltage, and the larger the current flowing, the smaller the closed-circuit voltage. Therefore, in advance, by measuring the same type of lithium-ion secondary battery 1, the voltage [V] corresponding to SOC [%] is measured. And if a conversion table based on these relationships is created, the measured voltage V M [V], SOC [%] can be immediately estimated.

[0027] On the other hand, in the current integration method, the SOC [%] of the lithium-ion secondary battery 1 can be estimated by integrating the current I [A]. That is, the current SOC [%] can be estimated by the ratio of the integrated value of ∫Idt [Wh] to the FCC (Full Charge Capacity) [Wh].

[0028] In this embodiment, such a battery model is used to estimate SOC [%]. <Available SOC range S U > As shown in FIG. 1, at SOC [%] based on the unused battery, the upper limit L H0 [%], which is the upper limit of the initial setting for normal use, is determined. In this embodiment, for example, it is set to 80 [%]. This is a margin to prevent overcharging even with regenerative current, for example, on a long downhill slope. On the other hand, the lower limit L L0Determine [%]. In this embodiment, for example, it is set to 20 [%]. This is a margin to prevent over-discharge even in the case of large discharge by driving power on a long uphill slope or the like, for example.

[0029] Such an upper limit L H0 and a lower limit L L0 The range sandwiched between them is the usable SOC range S U [%]. In this embodiment, it is in the range of 20 [%] or more to 80 [%] or less. However, in the case of a lithium-ion secondary battery 1 with an unknown usage history, etc., deterioration may progress, the battery capacity may decrease, or the internal resistance may increase. In such a case, even when the same measured voltage V M [V], or the same measured current A M [W], there may be an error in the SOC [%] estimated based on these.

[0030] <Step of information acquisition / Step of battery voltage estimation> In this embodiment, the SOC [%] is estimated based on a battery model. Here, the measured voltage V of the lithium-ion secondary battery 1 is actually obtained. M [V]. Also, at the same timing, the estimated voltage V E [V] is calculated by the battery model. Then, the difference ΔV [V] between the measured voltage V M [V] and the estimated voltage V E [V] is calculated. This difference ΔV [V] can be said to be caused because the battery model has deteriorated from the initial stage. Therefore, based on this ΔV [V], the estimation error E [%] of SOC [%] is obtained.

[0031] <Step of sample collection / Step of sample classification> Here, a "sample" is a sample for calculating the estimation error E [%]. Specifically, it is a sample of the difference ΔV [V] between the measured voltage V M [V] and the estimated voltage V E [V]. This measured voltage V M [V] and the estimated voltage V EThe error of the SOC is estimated based on the difference ΔV [V] of [V]. In this sample collection step, when a current I (measured current A M [W]) flows through the lithium-ion secondary battery 1 under certain conditions, samples for calculating the estimation error E [%] of the SOC are collected. Here, the "certain conditions" are defined, for example, as the measured current A M [W] being 1000 [W] or more and the duration being 5 [seconds]. This is to obtain significant data for SOC error estimation.

[0032] Also, the collected samples are classified based on a reference value S with respect to a preset normal SOC center. The reference value S is set to a value of 40 [%] or more and 60 [%] or less of the SOC. The reason is that generally, around the boundary of SOC 40 - 60 [%], the behavior is different between the high SOC region and the low SOC region. In this embodiment, the reference value S is set to 50 [%]. For example, if the measured voltage V M [V] = 4.000 [V], then at this time, the SOC is estimated to be 50% or more, and since it exceeds the reference value S, it is collected as an upper limit side determination sample SP H . On the other hand, if the measured voltage V M [V] = 3.500 [V], then at this time, the SOC is estimated to be 50% or less, and since it is less than the reference value S, it is collected as a lower limit side determination sample SP L .

[0033] Samples are collected in this way and classified and stored in the memory 102 (Fig. 5) of the control device 18 as the upper limit side determination sample SP H and the lower limit side determination sample SP L . The step of calculating the SOC estimation error calculates the upper limit error E H [%] based on the upper limit side determination samples Sam H collected in a certain number or more, and the lower limit error E L [%] based on the lower limit side determination samples Sam L .

[0034] <SOC Estimation Error Calculation Step> The estimation error E [%] of the SOC in this embodiment is calculated by the following formula. The calculation of the estimation error E [%] is performed separately for the upper limit determination sample SP H and the lower limit determination sample SP L . The upper limit determination sample SP H and the lower limit determination sample SP L are executed when a predetermined number of samples, for example, 10 samples in this embodiment, are collected.

[0035] Here, when the estimation error is E [%], the number of samples is N, the number of sample collection times is k, the measured voltage is VM [V], the estimated voltage is V E [V], and the voltage corresponding to 1 [%] of the SOC of the secondary battery is V1 [V], it is obtained by the following formula 1.

[0036]

Equation

[0037] Here, the voltage V1 [V] corresponding to 1 [%] of the SOC of the secondary battery is calculated as follows. For example, the voltage V1 [V] corresponding to SOC 1 [%] is set such that the voltage at SOC 100 [%] is 4.2 [V] and the voltage at SOC 0 [%] is 3.0 [V]. Then, when there is a difference of SOC 100 [%], the voltage difference V1 [V] is 4.2 - 3.0 = 1.2 [V]. Dividing this by 100, the voltage V1 [V] corresponding to SOC 1 [%] is approximately 0.012 [V] (12 [mV]).

[0038] Next, assume that the measured voltage V H obtained in the upper limit determination sample SP M [V] is 4.000 [V]. Also, assume that the calculated estimated voltage V E [V] is 4.100 [V].

[0039] Then V M - V E = 4.000 - 4.100 = -0.100 [V]. And the absolute value of (V M - V E ) │VM -V E becomes │V│ = 0.100. In this way, the obtained │V│ M -V E When │ is divided by V1, 0.100 ÷ 0.012 = 8.3, and in percentage, it becomes 8.3 [%].

[0040] In this embodiment, the upper limit error E [%] is repeatedly obtained by using ten upper limit determination samples SP H and the upper limit error E H [%] is calculated by its arithmetic mean. Here, it is assumed that the upper limit error E H [%] = 8.3 [%].

[0041] <Steps of upper and lower limit SOC reset> In the steps of upper and lower limit SOC reset, the upper limit L H of the used SOC is reset from the upper limit error E H , and the lower limit L L of the used SOC is reset from the lower limit error E L .

[0042] As shown in FIG. 1, the initial upper limit L H0 [%] was SOC = 80 [%]. However, when controlling charge and discharge at the initial SOC = 80 [%] upper limit L H0 [%], due to battery degradation, the battery capacity [Ah] may decrease, and in reality, it may be at a higher SOC [%].

[0043] Therefore, based on the upper limit error E H [%] calculated in the step of SOC estimation error calculation, the initial upper limit L H0 [%] is changed to the corrected upper limit L HR [%]. Similarly, based on the lower limit error E L [%] calculated in the step of SOC estimation error calculation, the initial lower limit L L0 [%] is changed to the corrected lower limit L LR [%]. Then, the initially available SOC range S U0 [%] is changed to the corrected available SOC range S U1Let it be [%]. In this embodiment, the initially available SOC range S U0 = 80 - 20 = 60[%] is the available SOC range S U1 [%] = (80 - 8.3) - (20 + 8.3) = 43.4[%].

[0044] <Steps of upper and lower limit guard processing> In the steps of upper and lower limit guard processing, guard processing is performed. In the steps of upper and lower limit SOC resetting, it is reset based on the estimation error E[%]. Here, the upper limit L H of the used SOC, the lower limit L L of the used SOC, based on which the available SOC range S U is optimized. "Optimization" is a process performed to ensure the range of the available SOC range S U1 [%]. That is, when the estimation error E[%] is too large, the actually available corrected available SOC range S U1 [%] may become extremely narrow.

[0045] Here, "upper limit L H1 = L H0 - (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax)... Equation 2" is Equation 2 for calculating the upper limit L H in the guard processing of this embodiment. "Lower limit L L1 = L L0 - (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax)... Equation 3" is Equation 3 for calculating the lower limit L L in the guard processing of this embodiment.

[0046] Here, (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax) means that the upper limit error E H is limited to the range of minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax. For example, let the minimum difference ΔMin[%] = 0[%] and the maximum difference ΔMax = 20[%.

[0047] In this case, if the upper limit error EH [%] is 8.3 [%] as described above, the minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax, so the guard process is not performed. Here, the measured voltage V H obtained in the upper limit side determination sample SP M [V] is assumed to be 4.011 [V]. Also, the calculated estimated voltage V E [V] is assumed to be 4.001 [V]. Then, the upper limit error E H obtained by Equation 1 is H = 83 [%]. Substituting this upper limit error E H = 83 [%] into Equation 2, since it is larger than the maximum difference ΔMax = 20 [%], the upper limit error E

[0048] Therefore, when applying "upper limit L H1 = L H0 - (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax)... Equation 2", upper limit L H1 = L H0 - (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax) = 80 - (20) = 60, and the upper limit L H1 does not fall below 60 [%].

[0049] Similarly, for the lower limit L L1 [%], "lower limit L L1 = L L0 - (minimum difference ΔMin ≤ upper limit error E H ≤ maximum difference ΔMax)... Equation 3" is applied. Here too, assume the minimum difference ΔMin [%] = 0 [%] and the maximum difference ΔMax = 20 [%].

[0050] The measured voltage V L obtained in the lower limit side determination sample SP M [V] is assumed to be 3.510 [V]. Also, the calculated estimated voltage V EAssume that [V] is 3.500 [V]. Then, the lower limit error E obtained by Equation 1 L = 83 [%]. Substituting this lower limit error E L = 83 [%] into Equation 2, since it is larger than the maximum difference ΔMax = 20 [%], the lower limit error E L is limited to 20 [%].

[0051] Therefore, applying "lower limit L L1 = L L0 - (minimum difference ΔMin ≤ lower limit error E L ≤ maximum difference ΔMax) … Equation 3", lower limit L L1 = L L0 + (minimum difference ΔMin ≤ lower limit error E L ≤ maximum difference ΔMax) = 20 + (20) = 40, and lower limit L L1 does not exceed 40 [%].

[0052] <Optimization of the corrected available SOC range S U1 > In the step of guard processing for the upper and lower limits, the upper limit L [%] set from the upper limit error E [%] is set within the range of the maximum difference ΔMax and the minimum difference ΔMin of the upper limit error E. Also, the lower limit L [%] set from the lower limit error E [%] is set within the range of the maximum difference ΔMax and the minimum ΔMin of the lower limit error E. In this case, "corrected available SOC range S H = initial set available SOC range S H - (maximum difference ΔMax of the upper limit error E H + maximum difference ΔMax of the lower limit error E) … Equation 4" is applied. Assume that the initial set available SOC range S L is set to 60 [%], and it is assumed that at least an available SOC range S L of 20 [%] is required in the actual vehicle. In this case, "corrected available SOC range S L = initial set available SOC range S U1 - (maximum difference ΔMax of the upper limit error E U0 + maximum difference ΔMax of the lower limit error E) … Equation 4" is applied. Assume that the initial set available SOC range S H is set to 60 [%], and it is assumed that at least an available SOC range S L of 20 [%] is required in the actual vehicle. In this case, "corrected available SOC range S U is set to 60 [%], and assume that at least an available SOC range S U of 20 [%] is required in the actual vehicle. In this case, "corrected available SOC range S U1=Available SOC range S for initial settings U0 60[%] - (maximum error E H of ΔMax + lower limit error E L of ΔMax) ≥ 20[%]... Equation 4. By doing this, the available SOC range S U1 [%] after correction can be made 20[%] or more. That is, (upper limit error E H of ΔMax + lower limit error E L of ΔMax) ≤ 40[%], so that the available SOC range S U1 after correction can be ensured to be 20[%] or more.

[0053] <Steps of battery model correction> In this embodiment, when the difference ΔV[V] between the measured voltage V M [V] and the estimated voltage V E [V] becomes equal to or greater than the threshold Th, the steps of battery model correction are executed. In the steps of battery model correction, by reviewing the register R0, R1, capacitor C1, etc. of the battery model as shown in FIG. 2, the difference ΔV[V] between the measured voltage V M [V] and the estimated voltage V E The threshold Th is defined by the voltage value [V]. Alternatively, it can also be defined by the ratio of the measured voltage V M [V] to the estimated voltage V E .

[0054] Alternatively, it can also be executed at other opportunities such as a certain usage time. (Configuration of this embodiment) <Configuration of lithium-ion secondary battery 1> FIG. 3 is a perspective view showing an outline of the external configuration of the lithium-ion secondary battery 1 of this embodiment. First, the configuration of the lithium-ion secondary battery 1 of this embodiment, which is an example of the present invention, will be described.

[0055] The lithium-ion secondary battery 1 shown in FIG. 3 is a cell battery, and a battery module 1M is composed of cell batteries (see FIG. 5). The lithium-ion secondary battery 1, which is a cell battery, includes a plate-shaped rectangular parallelepiped battery case 11 having an opening on the upper side. An electrode body 12 is housed inside the battery case 11. The battery case 11 is filled with a non-aqueous electrolyte 13 from a liquid injection hole. The battery case 11 is made of a metal such as an aluminum alloy and forms an electric cell sealed by a lid. The lithium-ion secondary battery 1 also includes a positive electrode external terminal 14 and a negative electrode external terminal 15 used for charging and discharging electric power. The positive electrode external terminal 14 is electrically connected to a positive electrode current collector terminal 16 inside the battery case 11 through the lid. Also, the negative electrode external terminal 15 is electrically connected to a negative electrode current collector terminal 17 inside the battery case 11 through the lid. The positive electrode current collector terminal 16 is electrically connected to the positive electrode current collecting portion 33 (see FIG. 4) of the electrode body 12. Also, the negative electrode current collector terminal 17 is electrically connected to the negative electrode current collecting portion 23 (see FIG. 3) of the electrode body 12.

[0056] <electrode body 12> FIG. 4 is a schematic diagram showing the configuration of the wound electrode body 12. The electrode body 12 is formed by laminating a large number of negative electrode plates 2, positive electrode plates 3, and separators 4 disposed therebetween. The laminated negative electrode plates 2, positive electrode plates 3, and separators 4 are wound to form a flat shape. The negative electrode plate 2 has a negative electrode composite material layer 22 formed on a negative electrode current collector 21 made of a copper foil as a base material. A negative electrode current collecting portion 23 is provided on one end side in the width direction W (winding axis direction) orthogonal to the winding direction L. The negative electrode current collecting portion 23 has a configuration in which the negative electrode composite material layer 22 is not formed and the negative electrode current collector 21 is exposed.

[0057] The positive electrode plate 3 has a positive electrode composite material layer 32 formed on a positive electrode current collector 31 made of an aluminum foil as a base material. As shown in FIG. 4, a positive electrode current collecting portion 33 is provided on the other end side (opposite side to the negative electrode current collecting portion 23) in the width direction W (winding axis direction) orthogonal to the direction (winding direction L) in which the positive electrode current collector 31 is wound. The positive electrode current collecting portion 33 has a configuration in which the positive electrode composite material layer 32 is not formed and the metal of the positive electrode current collector 31 is exposed.

[0058] <Laminated Structure of Electrode Body 12> As shown in FIG. 4, the basic configuration of the electrode body 12 of the lithium-ion secondary battery 1 includes a negative electrode plate 2, a positive electrode plate 3, and a separator 4.

[0059] The negative electrode plate 2 includes negative electrode composite layers 22 on both sides of a negative electrode current collector 21 serving as a negative electrode base material. One end portion of the negative electrode current collector 21 is a negative electrode current collecting portion 23 where the metal is exposed. The positive electrode plate 3 includes positive electrode composite layers 32 on both sides of a positive electrode current collector 31 serving as a positive electrode base material. The other end portion of the positive electrode current collector 31 is a positive electrode current collecting portion 33 where the metal is exposed.

[0060] The negative electrode plate 2 and the positive electrode plate 3 are stacked via the separator 4 to form a laminate. As shown in FIG. 3, this laminate is wound in the longitudinal direction around a winding axis to form a wound-type electrode body 12 that is flattened as shown in FIG. 5.

[0061] <Non-aqueous Electrolyte 13> The non-aqueous electrolyte 13 of the lithium-ion secondary battery 1 of the present embodiment shown in FIG. 3 penetrates into the electrode body 12. The non-aqueous electrolyte 13 is a composition in which a lithium salt is dissolved in an organic solvent. As the lithium salt, LiClO4, LiPF6, LiAsF6, LiBF4, LiSO3CF3, etc. can be used. As the organic solvent, cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, trifluoropropylene carbonate, chain carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane, sulfur compounds such as ethyl methyl sulfone, butane sultone, or phosphorus compounds such as triethyl phosphate, trioctyl phosphate, etc. can be mentioned. As the non-aqueous electrolyte 13, these can be used by mixing one or more of them. Note that the composition of the non-aqueous electrolyte 13 is not limited to this.

[0062] <Constituent Elements of Electrode Body 12> Next, the negative electrode plate 2, the positive electrode plate 3, and the separator 4, which are the components constituting the electrode body 12, will be described.

[0063] <Negative electrode plate 2> As shown in FIG. 4, the negative electrode plate 2 is constituted by forming negative electrode composite material layers 22 on both surfaces of a negative electrode current collector 21, which is a negative electrode base material. The negative electrode composite material layer 22 is formed by applying a negative electrode composite material paste 22a to the negative electrode current collector 21. Thereafter, the negative electrode plate 2 is completed through a drying process, a pressing process, and a cutting process.

[0064] <Negative electrode current collector 21> In this embodiment, the negative electrode current collector 21 is composed of a Cu foil. The negative electrode current collector 21 serves as a base as an aggregate of the negative electrode composite material layer 22 and has a function of a current collecting member that collects electricity from the negative electrode composite material layer 22. One end portion of the negative electrode current collector 21 is a negative electrode current collecting portion 23 where the metal surface is exposed without the formation of the negative electrode composite material layer 22. That is, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 via the negative electrode current collector 21, the negative electrode current collecting portion 23, and the negative electrode current collecting terminal 17.

[0065] <Negative electrode composite material layer 22> In this embodiment, the negative electrode active material is a powdery carbon material made of graphite (graphite) having a layered structure or the like, and is a material capable of occluding and releasing lithium ions Li + ions.

[0066] <Positive electrode plate 3> As shown in FIG. 4, the positive electrode plate 3 is composed of a positive electrode current collector 31, which is a positive electrode base material, and a positive electrode composite material layer 32 applied thereto. The positive electrode composite material layer 32 is formed by applying a positive electrode composite material paste to the positive electrode current collector 31. Thereafter, the positive electrode plate 3 is completed through a drying process, a pressing process, and a cutting process.

[0067] <Positive electrode current collector 31> A positive electrode plate 3 is formed by forming a positive electrode mixture layer 32 on both sides of a positive electrode current collector 31 which is a positive electrode base material. In the embodiment, the positive electrode current collector 31 is made of Al foil. The positive electrode current collector 31 serves as a base as an aggregate of the positive electrode mixture layer 32 and has a function of a current collecting member for collecting electricity from the positive electrode mixture layer 32.

[0068] First, although the Al foil was exemplified as the positive electrode base material constituting the positive electrode current collector 31, for example, it may be composed of a conductive material made of a metal with good conductivity. As a material with good conductivity, for example, in addition to Al foil, a material containing an Al alloy can be used. The configuration of the positive electrode current collector 31 is not limited to this.

[0069] <Positive electrode mixture layer 32> The positive electrode mixture layer 32 is formed by coating and drying a positive electrode mixture paste on the positive electrode current collector 31. The positive electrode mixture layer 32 contains, in addition to positive electrode active material particles, additives such as a conductive auxiliary material, a binder, and a dispersant.

[0070] <Composition of positive electrode active material> The positive electrode active material particles contain a lithium transition metal oxide having a layered crystal structure. The lithium transition metal oxide contains one or more predetermined transition metal elements in addition to Li. The transition metal element contained in the lithium transition metal oxide is preferably at least one of Ni, Co, and Mn. The positive electrode active material of this embodiment exemplifies a ternary system called so-called NCM having a lithium transition metal oxide containing all of Ni, Co, and Mn.

[0071] Note that the positive electrode active material of this embodiment is not limited to those having a lithium transition metal oxide containing all of Ni, Co, and Mn. Also, for example, a composition containing Al may be used in addition to these. Further, the positive electrode active material may be LiMnO4, LiFePO4, or the like.

[0072] <Separator 4> The separator 4 is a highly insulating non-woven fabric made of polypropylene or the like, which is a porous resin for holding the non-aqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. Also, as the separator 4, a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, and a porous polyvinyl chloride membrane, or a lithium ion or ion conductive polymer electrolyte membrane can be used alone or in combination.

[0073] <Overall configuration of a vehicle equipped with a secondary battery> FIG. 5 is a block diagram showing an example of the configuration of a vehicle using the lithium ion secondary battery 1 at the implementation stage. The vehicle illustrated in FIG. 5 is a hybrid vehicle. The vehicle includes a control device 18 that also functions as a charge / discharge control device for the lithium ion secondary battery 1, a power control unit (PCU) 30, motor generators 41 and 42, an engine 50, a power split device 60, a drive shaft 70, and drive wheels 80. The control device 18 of the lithium ion secondary battery 1 of the present embodiment includes a battery module 10A, a monitoring unit 40, and an ECU (electronic control unit) 100.

[0074] The engine 50 is an internal combustion engine that outputs power by converting the combustion energy generated when a mixture of air and fuel burns into the kinetic energy of moving elements such as pistons and rotors.

[0075] The power split device 60 includes, for example, a planetary gear mechanism (not shown) having three rotating shafts of a sun gear, a carrier, and a ring gear. The power split device 60 splits the power output from the engine 50 into the power for driving the motor generator 41 and the power for driving the drive wheels 80.

[0076] Each of the motor generators 41 and 42 is an AC rotating electric machine. For example, it is a three-phase AC synchronous motor in which a permanent magnet (not shown) is embedded in the rotor. The motor generator 41 is mainly used as a generator driven by the engine 50 via the power split device 60. The electric power generated by the motor generator 41 is supplied to the motor generator 42 or the lithium-ion secondary battery 1 via the PCU 30.

[0077] The motor generator 42 mainly operates as an electric motor and drives the drive wheels 80. The motor generator 42 is driven by receiving at least one of the electric power from the lithium-ion secondary battery 1 and the generated electric power of the motor generator 41, and the driving force of the motor generator 42 is transmitted to the drive shaft 70. On the other hand, during braking of the vehicle or when reducing acceleration on a downhill slope, the motor generator 42 operates as a generator to perform regenerative power generation. The electric power generated by the motor generator 42 is supplied to the battery module 1M via the PCU 30.

[0078] The battery module 1M includes the lithium-ion secondary battery 1 which is a plurality of cell batteries. The lithium-ion secondary battery 1 stores electric power for driving the motor generators 41 and 42, and supplies electric power to the motor generators 41 and 42 through the PCU 30. Further, the lithium-ion secondary battery 1 is charged by receiving the generated electric power through the PCU 30 during power generation of the motor generators 41 and 42.

[0079] The monitoring unit 20 includes a voltage measuring device 40a, a current measuring device 40b, and a temperature measuring device 40c. The voltage measuring device 40a of the present embodiment detects, for example, the voltage E of each cell battery of the lithium-ion secondary battery 1. However, the voltage E of the entire battery module 1M composed of a plurality of cells of the lithium-ion secondary battery 1 connected in parallel to each other may be detected. In this case, the voltage of each cell battery is estimated from the overall voltage. The current measuring device 40b detects the current I input to and output from the lithium-ion secondary battery 1. The temperature measuring device 40c detects the temperature T for each block. Each measuring device outputs a signal indicating the detection result to the ECU 100.

[0080] Note that the monitoring units of the voltage measurement device 40a and the temperature measurement device 40c are basically for each cell of the lithium ion secondary battery 1. However, it is not limited to this, and it may be for each block.

[0081] The PCU 30 performs bidirectional power conversion between the lithium ion secondary battery 1 and the motor generators 41 and 42 according to a control signal from the ECU 100. The PCU 30 is configured to be able to control the states of the motor generators 41 and 42 separately. For example, the motor generator 41 can be set in the regeneration state (power generation state) while the motor generator 42 is set in the power running state. The PCU 30 is provided corresponding to the motor generators 41 and 42, for example, and includes two inverters and a converter (both not shown) that boosts the DC voltage supplied to each inverter to be equal to or higher than the output voltage of the lithium ion secondary battery 1.

[0082] <ecu100> In this embodiment, the ECU 100 of the control device 18 serves as the part that controls the charging and discharging of this embodiment.

[0083] The ECU 100 includes a CPU (Central Processing Unit) 101, a memory 102, and an input / output port (not shown) for inputting and outputting various signals. <Memory 102> The memory 102 includes a ROM (Read Only Memory) and a RAM (Random Access Memory). Further, it is provided with a storage medium in which programs, maps, etc. are stored, such as an EPROM (erasable programmable read only memory), an SSD (Solid State Drive), an HDD (Hard Disc Drive), etc.

[0084] The ECU 100 controls the charging and discharging of the lithium-ion secondary battery 1 by controlling the engine 50 and the PCU 30 based on the signals received from each measuring device and the programs and maps stored in the memory 102.

[0085] FIG. 6 is a block diagram showing a part of the program stored in the memory 102. As shown in FIG. 6, the memory 102 stores a program that causes the CPU 101 to function as a current measurement unit 102a. Similarly, a voltage estimation unit 102b, an SOC estimation unit 102c, a voltage measurement unit 102d, a sample storage unit 102e, an SOC estimation error storage unit 102f, an upper and lower limit SOC calculation unit 102g, a used SOC calculation unit 102h, and a battery model correction unit 102i are stored. The memory 102 can store programs for performing respective processes and their results, etc.

[0086] <Control method for charging and discharging of the lithium-ion secondary battery 1 of this embodiment> FIG. 7 is a flowchart showing the procedure of the control method for charging and discharging of the lithium-ion secondary battery 1 of this embodiment. Hereinafter, the control method for charging and discharging of the lithium-ion secondary battery 1 of this embodiment will be described along the flowchart of FIG. 7.

[0087] First, start controlling the lithium-ion secondary battery 1 mounted on the vehicle shown in FIG. 5. Typically, this is the case when replacing the lithium-ion secondary battery 1 with an unknown usage history. Alternatively, this may also be the case when applying the charge and discharge control method of the lithium-ion secondary battery 1 of the present embodiment to the lithium-ion secondary battery 1 already mounted for the first time.

[0088] <Obtain current / voltage / temperature information (S1)> First, obtain current / voltage / temperature information (S1). Here, the ECU 100 of the monitoring unit 40 shown in FIG. 5 obtains the current / voltage / temperature information of each cell battery through the programs of the ammeter 102a, the voltmeter 102d, and the SOC estimator 102c (which measures temperature) in the memory 102.

[0089] Measured current A M [A] is the current measuring device 40b, measured voltage V M [V] is the voltage measuring device 40a, measured temperature T M [°C] is measured by the temperature measuring device 40c and stored in the memory 102. This procedure corresponds to the information acquisition step of the present embodiment.

[0090] <Input current / temperature information into the battery model, estimate the battery state, and estimate the battery voltage (S2)> Next, input the current / temperature information into the battery model, estimate the battery state, and estimate the battery voltage (S2). Here, the ECU 100 inputs the measured current A M [A] and the measured temperature T M [°C] into the battery model shown in FIG. 2 to estimate the battery state and estimate the estimated voltage V E [V]. This procedure corresponds to the battery voltage estimation step of the present embodiment.

[0091] <Compare the measured voltage information with the estimated voltage to correct the battery state estimation (S3)> Next, the state estimation of the battery is corrected by comparing the measured voltage information with the estimated voltage (S3). Here, the ECU 100 calculates the difference ΔV [V] between the measured voltage V M [V] and the estimated voltage V E [V]. In this case, when it is determined that the difference ΔV [V] is greater than a certain threshold value, the battery model is corrected as necessary. This procedure corresponds to the step of battery model correction in the present embodiment.

[0092] <Is the current flowing within a certain range? (S4)> Next, it is determined whether or not the current is flowing within a certain range (S4). Here, according to the program stored in the sample storage unit 102e of the ECU 100, it is determined whether or not a sample can be collected as a sample for a certain continuous time or a current equal to or greater than a certain current. This procedure corresponds to a part of the sample collection step in the present embodiment. If it is determined that the current is not flowing within a certain range (S4: NO), the process returns to S1.

[0093] <Collect samples for calculating the most recent SOC estimation error (S5)> If it is determined that the current is flowing within a certain range (S4: YES), the ECU 100 stores the sample SP according to the program stored in the sample storage unit 102e. When the current flow is less than a predetermined current [A] or the predetermined continuous time (for example, less than 1 [second]), it is not collected as a sample. Subsequently, data that meets the collection conditions is searched for. This procedure corresponds to a part of the sample collection step in the present embodiment.

[0094] <Classify whether the collected samples are for upper limit determination or lower limit determination based on the normal SOC center (S6)> The collected samples are classified (S6) as being for upper limit determination or lower limit determination based on the normal SOC center as a reference. In the present embodiment, if the sample is at or below SOC 50%, it is determined to be a sample for lower limit determination, and if the sample exceeds SOC 50%, it is determined to be a sample for upper limit determination. Here too, the ECU 100 classifies and stores the samples according to the program stored in the sample storage unit 102e. This procedure corresponds to the step of sample classification in the present embodiment.

[0095] <Has enough samples been collected? (S7)> Then, it is determined whether or not enough samples have been collected (S7). Here, "enough" means, for example, in the present embodiment, until the effective upper limit determination sample SP H and the lower limit determination sample SP L each reach 10 samples. It is considered that if 10 samples are collected, the influence of noise and bias on the charge and discharge control can be made sufficiently small.

[0096] Note that while one of the upper limit determination sample SP H and the lower limit determination sample SP L is being collected until the predetermined quantity is reached, the other sample may always be updated by adding and deleting new samples. If the number of samples of either is not yet a certain number (S7: NO), the process returns to S1 and continues.

[0097] <Calculate the SOC estimation errors for the upper and lower limits when the number of samples of either has been collected (S8)> When the number of samples of either has reached a certain number (S7: YES), the SOC estimation errors for the upper and lower limits are calculated (S8). Note that the SOC estimation errors may be calculated when both samples are available. Here, the ECU 100 calculates the SOC estimation errors according to the program stored in the SOC estimation error storage unit 102f and stores the results. This procedure corresponds to the step of calculating the SOC estimation errors in the present embodiment.

[0098] <Perform guard processing for the upper and lower limit errors (S9)> Here, guard processing for the upper and lower limit errors is performed (S9). Here, the ECU 100 executes processing using the program stored in the upper and lower limit SOC calculation unit 102g. This processing is executed only when necessary. That is, for example, when the corrected available SOC range S UR [%] shown in FIG. 1 is less than 20 [%], the processing is executed.

[0099] The SOC estimation errors on the upper limit side and the lower limit side are calculated (S8). This upper limit error E H [%] and the lower limit error E L [%], based on the available SOC range S U0 [%] in the initial setting, from the upper limit error E H [%] and the lower limit error E L [%] are restricted. From this, the corrected available SOC range S UR [%] is determined. In this case, the upper limit error E H [%] and the lower limit error E L [%] are restricted to a certain range. This procedure corresponds to the steps of the upper and lower limit guard processing of the present embodiment.

[0100] <Set the upper and lower limit SOCs from the upper / lower limit errors (S10)> The upper and lower limit SOCs are set from the upper / lower limit errors (S10), and the corrected available SOC range S UR [%] is set. Once set, the ECU 100 controls the charge and discharge of the lithium-ion secondary battery 1 based on this corrected available SOC range S UR [%] using the program stored in the used SOC calculation unit 102h. This procedure corresponds to the steps of the upper and lower limit SOC reset of the present embodiment.

[0101] <Is there a charge / discharge end request? (S11)> For example, if there is a request to end the charge and discharge, such as when the vehicle use stops (S11: YES), the charge and discharge are ended, and the control method for the charge and discharge of the lithium-ion secondary battery 1 of the present embodiment is ended. If there is no such request to end the discharge (S11: NO), the process returns to S1 and the processing continues.

[0102] (Operation of this Embodiment) The method for controlling charge and discharge of the lithium-ion secondary battery 1 of this embodiment shown in FIG. 7 aims to quickly correct the SOC usage range according to the SOC estimation error in a simple method and control charge and discharge safely and efficiently.

[0103] Therefore, the control device first measures the current A M [A], measured voltage V M [V], and measured temperature T M [°C] of the lithium-ion secondary battery 1 that is the basis of control (S1), and estimates the estimated voltage V E [V] (S2). Subsequently, samples for calculating the estimation error E [%] of SOC are collected (S5). Here, this sample is the difference ΔV [V] between the measured voltage V M [V] and the estimated voltage V E [V], and the upper limit error E M [%] and the lower limit error E E [%] are calculated from the difference between this measured voltage V H [V] and the estimated voltage V L [V] (S8). By paying attention to the voltage in this way, the upper limit error E H [%] and the lower limit error E L [%] can be calculated accurately and quickly.

[0104] And if necessary, guard processing is performed to limit the upper limit error E H [%] and the lower limit error E L [%]. By this guard processing, a certain amount of SOC [%] for controlling charge and discharge is ensured.

[0105] The upper limit L H of the used SOC from the upper limit error E H , and the lower limit L L of the used SOC from the lower limit error E L Reset it (S10). Then, based on the available SOC range after correction, charge and discharge of the lithium-ion secondary battery 1 are controlled. By having such a configuration, the charge and discharge control method of the lithium-ion secondary battery 1 in this embodiment effectively protects the lithium-ion secondary battery 1 from overcharging and over-discharging. Also, since the SOC [%] can be accurately estimated, the state of the lithium-ion secondary battery 1 can be accurately grasped, and its performance can be safely exhibited.

[0106] (Effect of this embodiment) (1) According to the charge and discharge control method of the lithium-ion secondary battery 1 in this embodiment, there is an effect that the SOC usage range can be quickly corrected according to the SOC estimation error by a simple method, and charge and discharge can be controlled safely and efficiently.

[0107] (2) In this embodiment, in the step of calculating the SOC estimation error, the upper limit error E H [%] based on the upper limit determination sample SP H that has gathered a certain number or more, and the lower limit error E L [%] based on the lower limit determination sample SP L are calculated. Therefore, there is an effect that the upper limit error E H [%] and the lower limit error E L [%] of the accurate SOC can be calculated in real time.

[0108] (3) In this embodiment, in the step of resetting the upper and lower limit SOC, the upper limit L H of the used SOC is reset from the upper limit error E H [%], and the lower limit L L of the used SOC is reset from the lower limit error E L . By separating the upper and lower parts, there is an effect that the range of SOC that can be used for charge and discharge control can be made into a more appropriate range.

[0109] (4) In the step of the upper and lower limit guard processing of this embodiment, when resetting based on the SOC estimation error E [%], the available SOC range S U Perform guard processing to optimize, for example, to 20%. For this reason, even when the estimated error E [%] of the SOC is calculated to be large, it is possible to appropriately guard the charge and discharge range performed by the control device so as not to interfere with the operation of the vehicle.

[0110] (5) In the step of estimating the battery voltage, the estimated voltage is estimated as the voltage V E [V], which is the open-circuit voltage of the secondary battery, by the battery model of the lithium-ion secondary battery 1 set in advance. For this reason, there is an effect that the estimated voltage V E [V] can be calculated in real time.

[0111] (6) In this embodiment, the measured voltage V M [V] and the estimated voltage V E [V] are compared to correct the battery model. For this reason, by feeding back the detected error, the battery model can be corrected, and there is an effect that the accuracy of the detection error of the SOC can be improved.

[0112] (7) The estimated error E of the SOC can be calculated in real time by using Equation 1. For this reason, there is an effect that the estimated error of the lithium-ion secondary battery 1 can be obtained in real time.

[0113] (8) The control method of the lithium-ion secondary battery 1 of this embodiment can control charging and discharging safely and efficiently according to the deterioration state of the battery even when the lithium-ion secondary battery 1 with a usage history is mounted on a vehicle.

[0114] (9) The control method of the lithium-ion secondary battery 1 of this embodiment can be easily applied to existing vehicles. (Alternative example) ○ In this embodiment, the plate-shaped lithium-ion secondary battery 1 mounted on a vehicle is exemplified, but it can also be applied to those mounted on ships or aircraft, or stationary batteries in homes or factories. Also, its shape is not limited to a cylindrical shape.

[0115] ○In this embodiment, the lithium-ion secondary battery 1 is exemplified as the secondary battery, but the type is not limited thereto, and other non-aqueous electrolyte secondary batteries, alkaline secondary batteries such as NiMH, all-solid-state batteries, etc. may be used.

[0116] ○The battery model shown in Fig. 2 is an example of a simplified model, and a more complex model may also be used. ○In this embodiment, the lithium-ion secondary battery 1 as the cell battery constituting the battery module 1M which is an assembled battery is exemplified, but it may also be in a form such as controlling a single cell battery or a battery pack including a plurality of battery modules. In this case, the measured current A M [A] and the measured voltage V M [V] may be measured directly for each cell battery or for the assembled battery.

[0117] ○In this embodiment, the SOC error estimation is calculated by Equation 1, but in the present invention, the method for estimating the SOC error is not limited thereto. ○In this embodiment, the SOC range is limited separately to an upper limit and a lower limit, but it may also be implemented to process the upper limit and the lower limit in common.

[0118] ○In this embodiment, the initial available SOC range S U0 is set to 20 to 80 [%], but depending on the characteristics of the battery, it can also be implemented below 20 [%] or exceeding 80 [%].

[0119] ○In the guard process, the SOC range that can be used for control is set to 20 [%], but it is not limited thereto. ○The numerical values and numerical ranges in this embodiment are given as examples and are not limited thereto. Those skilled in the art can appropriately optimize and implement them according to the characteristics of the battery. The number of exemplified samples, the time for sample acquisition, etc. are examples and are appropriately optimized by those skilled in the art.

[0120] ○ The flowchart shown in Fig. 7 is an example for explanation and is not limited thereto. Those skilled in the art can implement it by adding, deleting, replacing, or changing the procedures. ○ Needless to say, the present invention can be implemented by those skilled in the art by adding, deleting, or changing its configuration without departing from the scope of the claims.

Explanation of Signs

[0121] A M [A]…Measured current V M [V]…Measured voltage V E [V]…Estimated voltage V1[V]…Voltage corresponding to SOC1 [%] ΔV[V]…Difference between the measured voltage V M [V] and the estimated voltage V E [V] Th[V]…Threshold value (for battery model correction) T M [°C]…Measured temperature S[%]…Reference value based on the preset normal SOC center SP H …Upper limit determination sample SP L …Lower limit determination sample N…Number of samples k…Number of sample collections E[%]…Estimation error of SOC E H [%]…Upper limit error E L [%]…Lower limit error L H [%]…Upper limit of used SOC L H0 [%]…Upper limit of (initial set SOC) (ex: 80 [%]) L HR [%]…Upper limit of (used SOC after correction) L L [%]…Lower limit of used SOC L L0 [%]…Lower limit of (initial set SOC) (ex: 20 [%]) L LR [%]…(Corrected usable SOC) lower limit S U [%]…Width of usable SOC S U0 [%]…Width of usable SOC in initial setting S UR [%]…Corrected usable SOC range 1…Lithium ion secondary battery (cell battery) 1M…Battery module 11…Battery case 12…Electrode body 13…Non-aqueous electrolyte 14…Positive electrode external terminal 15…Negative electrode external terminal 16…Positive electrode current collecting terminal 17…Negative electrode current collecting terminal 2…Negative electrode plate 21…Negative electrode current collector 22…Negative electrode composite material layer 23…Negative electrode current collecting part 3…Positive electrode plate 31…Positive electrode current collector 32…Positive electrode composite material layer 33…Positive electrode current collecting part 4…Separator 18…Control device 30…PCU 40…Monitoring unit 40a…Voltage measuring device 40b…Current measuring device 40c…Temperature measuring device 100…ECU (computer) 101…CPU 102…Memory 102a…Current measurement part 102b…Voltage estimation part 102c…SOC estimation part 102d…Voltage measurement part 102e…Sample storage part 102f…SOC estimation error storage part 102g…Upper and lower limit SOC calculation part 102h…Usable SOC calculation part 102i…Battery model correction part

Claims

1. A method for controlling charging and discharging of a secondary battery by a control device, wherein the control device comprises: Measurement current A obtained by measuring the secondary battery Ｍ [A], measurement voltage V Ｍ [V], measurement temperature T Ｍ [°C], and an information acquisition step of acquiring information The measured current A obtained in the step of obtaining the information Ｍ [A], and the measured temperature T Ｍ [°C], based on the information, estimate the estimated voltage V Ｅ [V], and a battery voltage estimation step of estimating When a current I flows through the secondary battery under certain conditions, a measurement voltage V for calculating an estimation error E [%] of the SOC Ｍ [V] and an estimated voltage V Ｅ [V], a step of sample collection for collecting samples of a difference ΔV [V] between them, Based on the sample collected in the step of sample collection and based on a reference value S [%] with a preset normal SOC center as a reference, an upper limit determination sample SP Ｈ or a lower limit determination sample SP Ｌ and a sample classification step of classifying either; Upper limit determination sample SP Ｈ Upper limit error E Ｈ [%], and lower limit determination sample SP Ｌ Lower limit error E Ｌ [%] and a step of calculating an SOC estimation error for calculating the same, Upper limit error E Ｈ From [%] to the upper limit L of the used SOC Ｈ , Lower limit error E Ｌ From to the lower limit L of the used SOC Ｌ Steps for resetting the upper and lower limits of the SOC resetting, A method for controlling charging and discharging of a secondary battery, characterized by controlling the range of the used State of Charge (SOC) of the secondary battery.

2. The upper limit L of the SOC in use is reset based on the estimated error E [%] of the SOC calculated in the step of calculating the SOC estimation error in the step of resetting the upper and lower limit SOCs. Ｈ , the lower limit L of the SOC in use Ｌ Based on this, a guard process step for optimizing the available SOC range S Ｕ is performed, and a guard process for the upper and lower limits is carried out. The method for controlling charging and discharging of a secondary battery according to Claim 1, characterized by comprising.

3. The step of guard processing for the upper and lower limits is the upper limit L Ｈ , the lower limit L Ｌ . Based on this, the SOC range S Ｕ that can be used is 20% or more. The upper limit L Ｈ , the lower limit L Ｌ . The method for controlling charge and discharge of a secondary battery according to claim 2, characterized in that the settings of are controlled.

4. The step of upper and lower guard processing is: Upper limit error E Ｈ Upper limit L set from [%] Ｈ [%] is the upper limit error E Ｈ Set within the range of the maximum difference ΔMax and the minimum difference ΔMin, and the lower limit error E Ｌ Lower limit L set from [%] Ｌ [%] is the lower limit error E Ｌ The method for controlling charge and discharge of a secondary battery according to claim 3, characterized in that it is set within the range of the maximum difference ΔMax and the minimum difference ΔMin of E.

5. In the step of estimating the battery voltage, the estimated voltage is estimated as the voltage V Ｅ which is the open-circuit voltage of the secondary battery by the battery model of the secondary battery set in advance, and the method for controlling charge and discharge of the secondary battery according to claim 1, characterized in that.

6. The measured voltage V Ｍ [V] and the estimated voltage V Ｅ [V] are compared, and the method for controlling charge and discharge of a secondary battery according to claim 5, further comprising the step of correcting the battery model.

7. The step of correcting the battery model is performed when the difference ΔV [V] between the measured voltage V Ｍ [V] and the estimated voltage V Ｅ [V] is equal to or greater than a threshold value Th. The method for controlling charge and discharge of a secondary battery according to claim 6, characterized in that it is executed.

8. In the step of sample classification, a reference value S based on a preset normal SOC center for classifying the collected samples into upper limit side judgment samples or lower limit side judgment samples is set to a value of SOC 40 [%] or more and SOC 60 [%] or less. The method for controlling charging and discharging of a secondary battery according to Claim 1, characterized by this.

9. In the step of calculating the SOC estimation error, let the SOC estimation error be E [%], the number of samples collected be N, the number of times of sample collection be k, and the measured voltage be V Ｍ [V], the estimated voltage be V Ｅ [V], and when the voltage corresponding to 1 [%] of the SOC of the secondary battery is V １ [V], then The estimation error E [%] is 【Number 1】 Calculated by, and the method for controlling charging and discharging of a secondary battery according to Claim 1, characterized by this.

10. The secondary battery is a power source for driving a vehicle, The control device is mounted on the vehicle The method for controlling charging and discharging of a secondary battery according to Claim 1, characterized by this.

11. The secondary battery is a lithium-ion secondary battery, and the method for controlling charging and discharging of a secondary battery according to any one of Claims 1 to 10, characterized by this.

Images