JP2013101884A - Secondary battery temperature estimation method and secondary battery control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery temperature estimation method, with which it is possible to estimate an internal temperature of a secondary battery with precision, and a secondary battery control method with which it is possible to allow the secondary battery to fully exert its performance.SOLUTION: With a secondary battery temperature estimation method according to the present invention, an internal resistance map that is a relation among an internal resistance, a duration time, a SOC, and a temperature is obtained using an AC impedance method, and a temperature of a power storage part that is an internal temperature of a secondary battery is estimated by first obtaining an internal resistance of the power storage part on the basis of the internal resistance map, then calculating a calorific value of the power storage part using the obtained internal resistance, and using the calculated calorific value.

Description

  The present invention relates to a secondary battery temperature estimation method for estimating the temperature of a power storage unit, which is the internal temperature of the secondary battery, and a secondary battery control method based on the internal temperature of the secondary battery estimated by the method. About.

  In recent years, secondary batteries have attracted attention as power sources not only for portable electronic devices such as mobile phones and notebook computers, but also for vehicles such as hybrid vehicles and electric vehicles.

  Secondary batteries used as power sources for vehicles are large in size because they require a larger amount of power than those used in portable electronic devices. In addition, the secondary battery for a vehicle generates a large amount of heat because charging and discharging at a high rate are repeated according to changes in the running state. For this reason, in a large-sized secondary battery that generates a large amount of heat, its internal temperature tends to increase.

  In addition, secondary batteries must be used in accordance with their temperature. In particular, continuing to charge and discharge a secondary battery in a high temperature state at a high rate directly promotes deterioration of the secondary battery.

  For this reason, it is important to accurately estimate the internal temperature of a large secondary battery that generates a large amount of heat. This is because when the error between the estimated internal temperature and the actual internal temperature is large and the reliability is low, it must be used with a margin for the error. That is, the performance of the secondary battery is excessively limited. Moreover, it is not preferable to actually measure the internal temperature of the secondary battery because it increases costs.

  For example, Patent Document 1 discloses that the internal temperature of the secondary battery has a certain relationship with the internal resistance, and the internal resistance has a certain relationship with the value of SOC (State Of Charge). For this reason, the internal temperature of the secondary battery is estimated by correcting the internal resistance estimated using the equivalent circuit by the calculated value of the SOC and further by the relationship with the corrected internal resistance. As a result, the internal temperature of the secondary battery can be accurately estimated.

JP 2010-135075 A

  By the way, in Patent Document 1, it is said that the relationship between the internal resistance of the secondary battery and the SOC and the relationship between the internal resistance and the internal temperature are acquired in advance by experiments. However, these acquisition methods are not disclosed. Thus, it is conceivable to acquire these relationships while charging / discharging the secondary battery using a direct current that is a current that normally flows through the secondary battery.

  However, when DC current is used, these relationships cannot be obtained accurately. This is because when the direct current flows through the secondary battery, all of the internal resistance, the SOC, and the internal temperature change. That is, the internal temperature of the secondary battery is changing while the relationship between the internal resistance and the SOC is acquired while charging and discharging the secondary battery using the direct current. In addition, the SOC of the secondary battery is changing while the relationship between the internal resistance and the internal temperature is acquired while charging and discharging the secondary battery using DC current. For this reason, there is a possibility that there is a large error between the acquired relationship and the actual relationship. As a result, there may be a large error in the internal temperature of the secondary battery estimated using the acquired relationship and the actual internal temperature of the secondary battery.

  Furthermore, the relationship between the internal resistance, the SOC, and the internal temperature of the secondary battery changes even after the secondary battery starts charging and discharging and continues. Therefore, the accurate internal temperature of the secondary battery cannot be estimated without considering the relationship with the duration.

  The present invention has been made for the purpose of solving the problems of the prior art described above. That is, the problem is that the secondary battery temperature estimation method that can accurately estimate the internal temperature of the secondary battery and the control of the secondary battery that can fully demonstrate the performance of the secondary battery. Is to provide a method.

  The temperature estimation method of the secondary battery of the present invention made for the purpose of solving this problem is intended for a secondary battery having an electrode body having a power storage unit in which a positive electrode plate and a negative electrode plate are stacked with a separator interposed therebetween, The internal resistance of the secondary battery, the duration from the start of charging / discharging of the secondary battery, and the ratio of the remaining battery capacity to the fully charged battery capacity obtained using the AC impedance method. An internal resistance map, which is a relationship between a certain SOC and the temperature of the power storage unit, is prepared in advance, charging and discharging of the secondary battery is started, and power storage is performed at predetermined time intervals by dividing the duration time in advance. The internal resistance of the battery unit is obtained based on the internal resistance map, the calorific value of the power storage unit is calculated using the obtained internal resistance, and charging / discharging of the secondary battery is continued using the calculated calorific value. The estimated temperature of the power storage unit at the time A temperature estimating method for a secondary battery, characterized in that the output.

  The present inventor has obtained an internal resistance map that is an accurate relationship among the internal resistance, duration, SOC, and temperature of the secondary battery by using the AC impedance method. And the internal resistance of the secondary battery calculated | required using this internal resistance map is exact. Furthermore, the heat generation amount of the power storage unit calculated using the accurately determined internal resistance is accurate. Therefore, the temperature of the power storage unit, which is the internal temperature of the secondary battery, can be accurately estimated by using an accurate calorific value.

  Further, in the temperature estimation method for a secondary battery described above, a plurality of partial regions are defined by dividing the power storage unit into a width direction and a thickness direction, and the internal resistance of the power storage unit is set to a plurality of power storage units. The heat generation amount of the power storage unit is calculated for each of the plurality of parts, and the estimated temperature of the power storage unit is further calculated for each of the plurality of parts of the power storage unit in the width direction and the thickness direction. It is preferable to calculate by performing a simulation based on different thermal conductivities.

  The power storage unit is a portion where the positive electrode plate, the negative electrode plate, and the separator overlap. In the width direction of the power storage unit, the positive electrode plate and the negative electrode plate are continuous from the positive electrode end to the negative electrode end. That is, heat is easily transmitted in the width direction of the power storage unit by the current collectors of the positive electrode plate and the negative electrode plate having high thermal conductivity. For this reason, thermal conductivity is high in the width direction of the power storage unit. On the other hand, in the thickness direction of the power storage unit, positive plates and negative plates exist alternately via separators. An active material layer is formed on each of the positive electrode plate and the negative electrode plate in the power storage unit. That is, there is a positive electrode active material layer made of an oxide having particularly low thermal conductivity in the thickness direction of the power storage unit. For this reason, the thermal conductivity is low in the thickness direction of the power storage unit. In other words, the temperature of the electricity storage unit is accurately estimated by calculating for each portion of the electricity storage unit divided in the width direction and the thickness direction by simulation based on different thermal conductivities in the width direction and the thickness direction. can do.

  Moreover, in the temperature estimation method for the secondary battery described above, a detected temperature detected from at least a first portion located on the surface of the plurality of portions of the power storage unit, an estimated temperature of the first portion, and The detected voltage detected from the secondary battery is compared with the estimated voltage calculated from the internal resistance obtained using the internal resistance map, respectively, and the difference between the detected temperature and the estimated temperature of the first part is calculated. When at least one of the difference between the detected voltage of the secondary battery and the estimated voltage exceeds a predetermined allowable range for each of the plurality of portions of the power storage unit obtained based on the internal resistance map according to the difference Is preferably corrected so that both the difference between the detected temperature and the estimated temperature of the first portion and the difference between the detected voltage and the estimated voltage of the secondary battery are within the allowable range.

  Although it is not easy to detect the temperature inside the power storage unit, it is relatively easy to detect the temperature of the surface. Therefore, by detecting the temperature of the part located on the surface among the divided parts of the power storage unit and comparing it with the estimated temperature of the same part, if the estimated temperature error is large relative to the actual temperature, Can be detected. Further, by comparing the estimated voltage estimated from the internal resistance obtained using the internal resistance map with the actual detection voltage, this can be detected when the estimated temperature error of the power storage unit is large. This is because the internal resistance obtained using the internal resistance map is also used for calculating the estimated temperature. Furthermore, an accurate internal resistance can be obtained by correcting the internal resistance according to the difference between these comparisons.

  Further, in the temperature estimation method for the secondary battery described above, the estimated temperature and the estimated voltage for each of the plurality of parts of the power storage unit are recalculated using the corrected internal resistance for each of the plurality of parts of the power storage unit. It is preferable to do. The corrected internal resistance is more accurate than before the correction. Therefore, it is possible to estimate the accurate temperature of the power storage unit by recalculating the estimated temperature of the power storage unit using the corrected internal resistance.

  Further, in the method for estimating the temperature of the secondary battery described above, the secondary battery including a cooling device is targeted, and the estimated temperature for each of the plurality of parts of the power storage unit is further absorbed from the secondary battery by the cooling device. It is preferable to calculate by performing a simulation based on the amount of heat.

  In order to suppress the temperature rise of the secondary battery, a secondary battery having a cooling device is used. In this case, the temperature of the power storage unit can be accurately estimated by calculating with a simulation that takes into account the amount of heat absorbed by the cooling device.

  Further, in the temperature estimation method for the secondary battery described above, the detected temperature detected from at least the first portion located on the surface of the plurality of portions of the power storage unit is compared with the estimated temperature of the first portion. If the difference between the detected temperature of the first portion and the estimated temperature exceeds a predetermined allowable range, the endothermic amount is determined according to the difference between the detected temperature of the first portion and the estimated temperature. Is preferably corrected so as to be within the allowable range.

  In a secondary battery including a cooling device, it is preferable to estimate the temperature of the power storage unit in consideration of the amount of heat absorbed by the cooling device. However, it is difficult to always obtain an accurate endothermic amount, and there may be a large error in the obtained endothermic amount. Therefore, by detecting the temperature of the portion located on the surface among the divided portions of the power storage unit and comparing it with the estimated temperature of the same portion, this can be detected when the error in the heat absorption amount is large. Furthermore, the correct endothermic amount can be obtained by correcting the endothermic amount according to the difference of the comparison.

  In the secondary battery temperature estimation method described above, it is preferable that the estimated temperature for each of the plurality of portions of the power storage unit is calculated again based on the corrected endothermic amount. The corrected endothermic amount is more accurate than before the correction. Therefore, the accurate temperature of the power storage unit can be estimated by recalculating the estimated temperature of the power storage unit using the corrected endothermic amount.

  The secondary battery control method of the present invention is a secondary battery control method for controlling the secondary battery based on the estimated temperature of the power storage unit calculated by the secondary battery temperature estimation method described above. In the secondary battery control method, the current flowing in the secondary battery is limited when the estimated temperature of the power storage unit is higher than a predetermined temperature.

  Such a control method of the secondary battery limits the use of the secondary battery based on the estimated temperature of the power storage unit accurately calculated by the above-described temperature estimation method of the secondary battery. For this reason, the performance of the secondary battery can be sufficiently exerted without excessively limiting the performance of the secondary battery.

  The secondary battery control method of the present invention is a secondary battery control method for controlling a secondary battery based on the estimated temperature of the power storage unit calculated by the secondary battery temperature estimation method described above. In the secondary battery control method, the cooling state of the cooling device is controlled so that the cooling effect of the secondary battery is increased when the estimated temperature of the part is higher than a predetermined temperature.

  In such a secondary battery control method, cooling is performed based on the estimated temperature of the power storage unit accurately calculated by the secondary battery temperature estimation method described above. For this reason, unnecessary cooling is not performed, and the power required for cooling can be minimized.

  According to the present invention, there are provided a secondary battery temperature estimation method capable of accurately estimating the internal temperature of the secondary battery, and a secondary battery control method capable of sufficiently exerting the performance of the secondary battery. Is provided.

It is a figure for demonstrating the vehicle which concerns on embodiment. It is a figure for demonstrating the secondary battery system which concerns on embodiment. It is sectional drawing of the secondary battery which concerns on embodiment. It is a figure for demonstrating the electrode body of the secondary battery which concerns on embodiment. It is an internal resistance map concerning an embodiment. In the internal resistance map according to the embodiment, the relationship between the internal resistance and the duration when the temperature of the secondary battery is constant at 0 ° C. and the SOC is 30%, 40%, 50%, and 60%. FIG. In the internal resistance map according to the embodiment, the relationship between the internal resistance and the duration when the SOC of the secondary battery is constant at 60% and the temperature is 0 ° C., 10 ° C., 20 ° C., and 30 ° C. FIG. It is a figure for demonstrating the division | segmentation of the electrical storage part of the secondary battery which concerns on embodiment. It is a top view of the electrical storage part of the secondary battery which concerns on embodiment. It is a flowchart which shows the procedure of the estimation method of the internal temperature of the secondary battery which concerns on embodiment. It is the figure showing the image of the distribution of the temperature of the electrical storage part during charging / discharging. It is the internal resistance map which showed only the relationship between internal resistance and SOC used for experiment. It is the internal resistance map which showed only the relationship between internal resistance, duration, and SOC used for experiment. It is a graph which shows the relationship between the duration in an experiment, and a voltage. It is a graph which shows the relationship between the duration in an experiment, and internal temperature.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for embodying the present invention will be described below in detail with reference to the drawings. In the present embodiment, the present invention is embodied in a secondary battery system of a hybrid vehicle.

[Overall schematic configuration]
FIG. 1 shows a vehicle 1 according to this embodiment. The vehicle 1 is a hybrid vehicle that can be driven by using the engine 3, the front motor 4 and the rear motor 5 in combination. As shown in FIG. 1, the vehicle 1 includes an engine 3, a front motor 4, a rear motor 5, a secondary battery system 6, a cable 7, and a vehicle ECU 80 inside a vehicle body 2.

  FIG. 2 is a schematic configuration diagram for explaining the secondary battery system 6. As shown in FIG. 2, the secondary battery system 6 includes an assembled battery 10 and a controller 20. The controller 20 includes a calculation unit 21, a memory 22, a communication unit 23, a current detection unit 30, a voltage detection unit 40, a temperature detection unit 50, a cooling state detection unit 60, and a cooling state control unit 70.

  The controller 20 calculates the state of the assembled battery 10 in the calculation unit 21 based on information from each detection unit. Although details will be described later, the calculation unit 21 calculates the SOC of the assembled battery 10, the temperature state of the assembled battery 10, and the like. The calculation unit 21 is connected to the vehicle ECU 80 via the communication unit 23. The vehicle ECU 80 uses the assembled battery 10 with the optimal power in the vehicle 1 based on the information of the assembled battery 10 from the communication unit 23.

  The assembled battery 10 is obtained by connecting a plurality of secondary batteries 100 in series with each other. The secondary battery 100 of this embodiment is a lithium ion secondary battery.

  FIG. 3 shows a cross-sectional view of the secondary battery 100 according to this embodiment. As shown in FIG. 3, the secondary battery 100 includes an electrode body 120, an electrolytic solution 130, and a battery case 140 that accommodates the electrode body 120 and the electrolytic solution 130. The battery case 140 includes a battery case main body 141 and a sealing plate 142. In addition, the sealing plate 142 includes an insulating member 143.

  FIG. 4 is a perspective view of the electrode body 120. As shown in FIG. 4, the electrode body 120 is a flat wound electrode body. The electrode body 120 is manufactured by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween. Also, as shown in FIG. 4, the X direction of the electrode body 120 is the width direction, the Y direction is the thickness direction, and the Z direction is the height direction.

The positive electrode plate is in the form of a strip formed by forming a positive electrode active material layer on the surface of an aluminum foil as a current collector. The positive electrode active material layer contains a positive electrode active material capable of inserting and extracting lithium ions. As the positive electrode active material, lithium metal oxides typified by lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMnO ₂ ), lithium nickelate (LiNiO ₂ ), and the like can be used.

  The negative electrode plate is a belt-shaped member formed by forming a negative electrode active material layer on the surface of a copper foil as a current collector. The negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions. As the negative electrode active material, a carbon-based material, a lithium transition metal composite oxide, a lithium transition metal composite nitride, or the like can be used.

  The separator is a porous member that can transmit lithium ions while preventing a short circuit between the positive electrode plate and the negative electrode plate. As the material of the porous member, polypropylene (PP), polyethylene (PE), or the like can be used.

  As illustrated in FIG. 4, the electrode body 120 includes a power storage unit 121, a positive electrode end 122, and a negative electrode end 123. The positive electrode end 122 is a right end portion of the electrode body 120 in the width direction X. The negative electrode end 123 is a left end portion of the electrode body 120 in the width direction X. The power storage unit 121 is a central portion in the width direction X of the electrode body 120 sandwiched between the positive electrode end 122 and the negative electrode end 123.

  The positive electrode end portion 122 is a portion composed of only a positive electrode plate. Further, in the portion of the positive electrode end portion 122 of the positive electrode plate, the positive electrode active material layer is not formed, and the aluminum foil is exposed. The negative electrode end portion 123 is a portion constituted only by a negative electrode plate. Moreover, in the part of the negative electrode edge part 123 of a negative electrode plate, the negative electrode active material layer is not formed but copper foil is exposed.

  The power storage unit 121 is a portion configured by a positive electrode plate, a negative electrode plate, and a separator. And in the part of the electrical storage part 121 of a positive electrode plate, the positive electrode active material layer is formed. Further, a negative electrode active material is formed in the portion of the power storage unit 121 of the negative electrode plate. For this reason, the electrical storage part 121 is a part which can contribute to charging / discharging.

  In the secondary battery 100, a positive electrode terminal 150 is connected to the positive electrode end 122 as shown in FIG. 3. A negative electrode terminal 160 is connected to the negative electrode end portion 123. Each of the positive terminal 150 and the negative terminal 160 has ends 151 and 161 that are not connected to the electrode body 120 protruding outside the battery case 140 via an insulating member 143 provided on the sealing plate 142. In the assembled battery 10, a plurality of secondary batteries 100 are connected in series by a positive electrode terminal 150 and a negative electrode terminal 160.

  Further, the secondary batteries 100 are charged and discharged in the power storage unit 121 of the electrode body 120 via the positive terminal 150 and the negative terminal 160, respectively. The secondary battery 100 generates heat in the power storage unit 121 as it is charged and discharged.

  As shown in FIG. 2, the assembled battery 10 includes an intake port 11 for taking in the cooling medium from the outside of the assembled battery 10 and a cooling medium after heat exchange in order to cool the secondary battery 100 that has generated heat. And a discharge port 12 for discharging the battery pack 10 to the outside. The cooling medium in this embodiment is air. Further, the discharge port 12 is provided with a fan 13. The fan 13 is for cooling air to flow efficiently in the assembled battery 10 and is a cooling device driven by a motor 14.

  The current detection unit 30 included in the controller 20 is for detecting a current value flowing through a circuit connected to the assembled battery 10. The voltage detection unit 40 is for detecting each voltage of the secondary battery 100 constituting the assembled battery 10.

  The temperature detector 50 is for detecting the actual internal temperature of each of the secondary batteries 100 constituting the assembled battery 10. Here, the temperature detection unit 50 of the present embodiment detects the temperature of a part of the power storage unit 121 that is the heat source for all the secondary batteries 100. For this reason, a temperature sensor is attached to the part of the electricity storage unit A1, which will be described in detail later, in the electricity storage unit 121.

  The cooling state detection unit 60 is for detecting the cooling state of the assembled battery 10. Therefore, the intake port 11 is provided with an intake air temperature sensor 61 that detects the temperature of the cooling air sucked into the assembled battery 10. The discharge port 12 is provided with a discharge temperature sensor 62 for detecting the temperature of the cooling air discharged from the assembled battery 10. The cooling state detection unit 60 detects the intake air temperature and the exhaust air temperature of the cooling air by the intake air temperature sensor 61 and the exhaust air temperature sensor 62.

  When the calculation unit 21 determines that the assembled battery 10 needs to be cooled, the cooling state control unit 70 drives the motor 14 and operates the fan 13. Moreover, when the calculating part 21 judges that cooling of the assembled battery 10 is unnecessary, this is stopped. Accordingly, the calculation unit 21 always knows whether or not the fan 13 is operating.

  The memory 22 stores various data regarding the secondary battery 100. For example, the anisotropy of the thermal conductivity of the power storage unit 121 and the internal resistance map 200 of the secondary battery 100 (see FIG. 5).

  The anisotropy of the thermal conductivity of the power storage unit 121 is related to the structure of the power storage unit 121. The thermal conductivity of the power storage unit 121 is not uniform, and is different in the width direction X and the thickness direction Y due to its structure. As described above, the power storage unit 121 is a portion configured by winding the positive electrode plate, the negative electrode plate, and the separator. In the positive electrode plate and the negative electrode plate in the power storage unit 121, an active material layer is formed on the surface of the current collector. In the width direction X of the power storage unit 121, the positive electrode plate and the negative electrode plate are continuous from the positive electrode end 122 to the negative electrode end 123. On the other hand, in the thickness direction Y of the power storage unit 121, the positive plates and the negative plates are alternately present via the separators.

  And in the width direction X of the electrical storage part 121, heat conductivity is high. This is because aluminum foil and copper foil having high thermal conductivity, which are current collectors of the positive electrode plate and the negative electrode plate, are continuous in the width direction X of the power storage unit 121. On the other hand, the thermal conductivity is low in the thickness direction Y of the power storage unit 121. This is because lithium metal oxide contained in the positive electrode active material layer having particularly low thermal conductivity exists in the thickness direction Y of the power storage unit 121. The memory 22 stores the anisotropy of the thermal conductivity of the power storage unit 121 that is high in the width direction X and low in the thickness direction Y.

  The internal resistance map 200 is created in advance by experiments, and represents the relationship between internal resistance, duration, SOC, and temperature. The internal resistance is the internal resistance of the secondary battery 100 when the secondary battery 100 is charged and discharged. The duration is the time during which the secondary battery 100 has been charged and discharged and has been continued. The SOC represents the remaining battery capacity of the secondary battery 100 as a ratio with respect to the fully charged battery capacity. The temperature is the temperature of the power storage unit 121 that is the internal temperature of the secondary battery 100.

  Here, it is difficult to obtain an accurate relationship among the internal resistance, duration, SOC, and temperature of the secondary battery 100 by flowing a direct current through the secondary battery 100. This is because all of these parameters change when a direct current flows through the secondary battery 100.

  Therefore, the present inventor created an internal resistance map 200 of the secondary battery 100 shown in FIG. 5 by conducting an experiment using the AC impedance method. Specifically, an experimental circuit was fabricated using the secondary battery 100, and the relationship between the internal resistance, duration, SOC, and temperature of the secondary battery 100 was acquired while an alternating current was passed through the circuit.

The impedance Z of the secondary battery 100 when an alternating current is passed through the experimental circuit is expressed by the following equation.
Z = Re (Z) + jIm (Z) (1)

  As shown in Equation (1), the impedance Z is represented by its real part Re (Z) and imaginary part Im (Z). Then, the real part Re (Z) of the impedance Z when an alternating current flows through the secondary battery 100 was used as the internal resistance of the secondary battery 100.

  Further, the secondary battery 100 while the alternating current is flowing repeats charging and discharging every half cycle of the alternating current. Therefore, the reciprocal (1 / 2f) twice the frequency f of the alternating current flowing through the secondary battery 100 is defined as the duration after the secondary battery 100 starts charging or discharging.

  Further, the SOC of the secondary battery 100 while the alternating current is flowing hardly changes from the SOC before the alternating current flows. This is because the secondary battery 100 continuously repeats charging and discharging by flowing an alternating current. Furthermore, the SOC of the secondary battery 100 can be set to a desired value by charging and discharging before flowing an alternating current.

  In addition, this experiment was performed in a state where the secondary battery 100 was housed in a temperature control device capable of controlling the environmental temperature. The secondary battery 100 generates heat even when an alternating current flows. For this reason, the temperature control device while the alternating current flows can control the environmental temperature of the secondary battery 100 to keep the entire temperature of the secondary battery 100 constant. That is, the heat generated by the secondary battery 100 can be cooled. Furthermore, the temperature control device can change the environmental temperature of the secondary battery 100 before flowing an alternating current. Thereby, the whole secondary battery 100 can be brought to a desired temperature before an alternating current is passed.

  As described above, in this experiment, it is possible to allow an alternating current to flow while fixing the SOC and temperature of the secondary battery 100 to constant values. Further, the parameter of the duration 1 / 2f is determined by the frequency f of the alternating current flowing through the secondary battery 100. That is, in this experiment, the internal resistance of the secondary battery 100 in that state can be acquired without changing the parameters of duration, SOC, and temperature. Therefore, the relationship between internal resistance, duration, SOC, and temperature can be acquired accurately.

  Also, the parameters of duration, SOC and temperature can be individually changed. That is, by changing the frequency f, the parameter of the duration 1 / 2f was changed within the range required for the internal resistance map 200. Further, every time an alternating current is applied, the SOC and temperature of the secondary battery 100 are individually changed within the range required for the internal resistance map 200. Then, the internal resistance map 200 was completed by measuring the internal resistance for each condition in which the parameters of duration, SOC, and temperature were changed.

  In this embodiment, an alternating current was passed through the secondary battery 100 at various frequencies f in the range of 5 to 0.005 Hz. Then, the value of the real part Re (Z) of the impedance Z measured at that time was taken as the internal resistance when this continued for 1/2 f (0.1 to 100 s) after the start of charging or discharging. Specifically, the internal resistance was measured when the duration 1 / 2f was 0.1 s by passing an alternating current having a frequency f of 5 Hz. Further, by passing alternating currents of various frequencies f in the range of 0.5 to 0.005 Hz such that the duration 1 / 2f is 1 s in the range of 1 to 100 s, 1 to 1 of the duration 1 / 2f. The internal resistance in the range of 100 s was measured. That is, the duration parameter prepared in the internal resistance map 200 is 0.1 s, and is 1 s in the range of 1 to 100 s.

  Further, in the secondary battery 100 of the present embodiment, the SOC range required for the internal resistance map 200 is set to a range of 0 to 100%. Moreover, the range of the internal temperature of the required secondary battery 100 was made into the range of -20-50 degreeC.

  6 and 7 are graphs showing a part of the internal resistance map 200 shown in FIG. 6 and 7, the horizontal axis represents the duration (1 / 2f). The vertical axis represents the internal resistance of the secondary battery 100 (the real part Re (Z) of the impedance Z).

  FIG. 6 is a graph showing the relationship between the internal resistance and the duration when the temperature of the secondary battery 100 is constant at 0 ° C. and the SOC is 30%, 40%, 50%, and 60%. is there. As shown in FIG. 6, the value of the internal resistance decreases as the SOC increases in the order of 30%, 40%, 50%, and 60%.

  FIG. 7 is a graph showing the relationship between the internal resistance and the duration when the SOC of the secondary battery 100 is constant at 60% and the temperatures are 0 ° C., 10 ° C., 20 ° C., and 30 ° C. is there. As shown in FIG. 7, the value of the internal resistance decreases as the temperature increases in the order of 0 ° C., 10 ° C., 20 ° C., and 30 ° C.

  Furthermore, as shown in FIGS. 6 and 7, the value of the internal resistance increases as the duration time increases even if the SOC and temperature are constant. And the memory 22 has memorize | stored the internal resistance map 200 which is the relationship between internal resistance, duration, SOC, and temperature acquired using the above alternating current impedance methods.

  In this embodiment, the frequency f of the alternating current is in the range of 5 to 0.005 Hz. For this reason, the duration 1 / 2f prepared in the internal resistance map 200 of this embodiment is in the range of 0.1 to 100 s. However, when the internal resistance map 200 requires a range after the duration of 100 s, this range can be obtained by using an alternating current having a lower frequency f. It is also possible to obtain the range after the duration of 100 s by extrapolation based on the range of 0.1 to 100 s.

  2 is based on information from the memory 22, the current detection unit 30, the voltage detection unit 40, the temperature detection unit 50, and the cooling state detection unit 60. Each SOC and internal temperature of the secondary battery 100 are calculated.

  Calculation unit 21 estimates the temperature of power storage unit 121 that is a heat source in secondary battery 100. Specifically, as shown in FIG. 8, the calculation unit 21 divides the power storage unit 121 into a plurality of parts, and estimates the temperature distribution for each part, thereby estimating the internal temperature distribution of the secondary battery 100. . In this embodiment, the power storage unit 121 is divided into five in the width direction X and the thickness direction Y, respectively. That is, the power storage unit 121 is divided into 25 parts of the power storage units A1 to A25. And the calculating part 21 estimates temperature about each of the part of electrical storage part A1-A25.

  In this embodiment, the power storage unit 121 is divided into five parts in the width direction X and the thickness direction Y, respectively, but the number of divisions is not limited to this. Further, although the power storage unit 121 is divided only in the width direction X and the thickness direction Y, it may be divided in the height direction Z in addition to the width direction X and the thickness direction Y.

  FIG. 9 shows the power storage unit 121 when FIG. 8 is viewed from above. As described above, the temperature sensor 51 is attached to the power storage unit A1 shown in FIG. And the part of electrical storage part A1 is a part located in the surface among the electrical storage parts 121. FIG. This is because it is difficult to attach the temperature sensor 51 to the inside of the power storage unit 121, but it can be easily attached to the surface. In the assembled battery 10 of this embodiment, the temperature sensor 51 is attached to the portion of the power storage unit A1 of all the secondary batteries 100.

  The communication unit 23 transmits the SOC and the internal temperature distribution of each secondary battery 100 calculated by the calculation unit 21 to the vehicle ECU 80. The vehicle ECU 80 charges or discharges the assembled battery 10 according to the information of the individual secondary batteries 100 acquired from the communication unit 23. For example, the vehicle ECU 80 charges the assembled battery 10 by, for example, the remaining power of rotation of the engine 3 while the vehicle 1 is traveling. Further, for example, when the vehicle 1 that is in a traveling state is braked, regenerative charging is performed at the time of braking. Further, the vehicle ECU 80 discharges the assembled battery 10 when the front motor 4 and the rear motor 5 are driven to drive the vehicle 1, for example. Then, the vehicle ECU 80 charges and discharges the assembled battery 10 according to the internal temperature acquired for each secondary battery 100 constituting the assembled battery 10.

[Internal temperature estimation method]
A method for estimating the internal temperature of the secondary battery 100 by the secondary battery system 6 according to the present embodiment will be described with reference to the flowchart of FIG. In the secondary battery system 6 shown in FIG. 2, the internal temperature of each secondary battery 100 constituting the assembled battery 10 is estimated by simulation every predetermined time t while charging or discharging is started.

  Below, the estimation method of the internal temperature in the nth time by the secondary battery system 6 is demonstrated. Here, the n-th time described below refers to the second and subsequent times except for the first time after the start of charging / discharging. A method for estimating the internal temperature of the secondary battery 100 in the first time will be described after the description for the nth time.

  The secondary battery system 6 estimates the internal temperature of the secondary battery 100 at the n-th time by repeating the following processing every predetermined time t. Therefore, the charging / discharging is continued for nt time from the time when charging / discharging is started to the nth time. Further, the estimation of the internal temperature of the secondary battery 100 at the n-th time is performed according to the procedure shown in the flowchart of FIG. Note that the predetermined time t in this embodiment is 1 s.

  Then, the secondary battery system 6 at the n-th time stores, in the memory 22, the previous SOC (n−1) for each secondary battery 100 calculated at the previous time (n−1 time) before the predetermined time t. . In addition, the memory 22 stores the previous temperatures TeA1 (n−1) to TeA25 (n−1) for each of the power storage units A1 to A25 for each secondary battery 100. The previous SOC (n-1) and the previous temperatures TeA1 (n-1) to TeA25 (n-1) are stored in the same procedure as the n-th procedure described below. And these memory | storages are memorize | stored for every secondary battery 100 which comprises the assembled battery 10 in step S108 mentioned later.

  First, the secondary battery system 6 in the n-th time has a current value I, a voltage V, a temperature TA1, and a cooling state C in each of the current detection unit 30, the voltage detection unit 40, the temperature detection unit 50, and the cooling state detection unit 60. It is detected (S101). In the calculation unit 21, each detection unit detects a detection value and receives the detection value.

  Moreover, the calculating part 21 calculates SOC (n) of the secondary battery 100 in the nth time (S102). The SOC (n) is calculated by adding the amount of change in the SOC changed during the predetermined time t to the previous SOC (n−1) stored in the memory 22. The amount of change in the SOC is calculated by integrating the current value I for a predetermined time t.

  Next, the calculation unit 21 calculates the estimated temperature TeA1 (n) to TeA25 (n) at the n-th time for each of the power storage units A1 to A25 obtained by dividing the power storage unit 121 of the secondary battery 100 (S103). At the same time, the estimated voltage Ve (n) of the secondary battery 100 at the nth time is calculated (S103).

  A method for calculating the estimated temperatures TeA1 (n) to TeA25 (n) will be described. Estimated temperatures TeA1 (n) to TeA25 (n) are changes that have changed from the previous temperatures TeA1 (n-1) to TeA25 (n-1) during the predetermined time t of the power storage units A1 to A25, respectively. Calculated by adding the temperatures ΔTeA1 to ΔTeA25. Further, the change temperatures ΔTeA1 to ΔTeA25 are calculated by performing simulations using the respective calorific values QA1 to QA25 due to charging and discharging of the power storage units A1 to A25 during a predetermined time t.

Here, as a representative of the heat generation amounts QA1 to QA25, a method for calculating the heat generation amount QA1 of the power storage unit A1 will be described. The calorific value QA1 of the power storage unit A1 is calculated from the internal resistance RA1 and the current value I of the power storage unit A1 during the predetermined time t. Specifically, it is calculated using the following equation (2).
QA1 = RA1 · I ² · t (2)

  The internal resistance RA1 can be obtained using the internal resistance map 200. Specifically, the computing unit 21 first obtains the previous SOC (n−1) and the previous temperature TeA1 (n−1) from the memory 22. Further, from the time when charging / discharging is started to the previous (n−1) th time, charging / discharging is continued for (n−1) t time. Therefore, this is set as the duration (n-1) t, and the internal resistance map 200 stored in the memory 22 is referred to together with the previous SOC (n-1) and the previous temperature TeA1 (n-1), and the power storage unit A1 The internal resistance RA1 of the part is obtained.

  In addition, the arithmetic unit 21 calculates the internal resistance RA2 to the internal resistance RA25 of each of the power storage units A2 to A25 as well as the internal resistance RA1 of the power storage unit A1. Further, similarly to the calorific value QA1 of the power storage unit A1, the calorific values QA2 to QA25 of the power storage units A2 to A25 are also calculated.

  FIG. 11 is a diagram showing an image of the temperature distribution of power storage unit 121 while being charged / discharged. In FIG. 11, among the portions of the power storage units A <b> 1 to A <b> 25, the higher the temperature, the closer the hatching. That is, as shown in FIG. 11, in the power storage unit 121 during charging / discharging, the temperature at the center is higher and the temperature near the outer periphery is lower.

  Thereby, the previous temperatures TeA1 (n-1) to TeA25 (n-1) are different values. That is, the internal resistance RA1 to the internal resistance RA25 obtained using different previous temperatures have different values as described above with reference to FIG. Therefore, the calorific values QA1 to QA25 calculated using different internal resistances also have different values. That is, the calorific value of the power storage unit 121 at the n-th time is not uniform, and is different for each of the power storage units A1 to A25.

  Furthermore, the calorific values QA1 to QA25 of the power storage units A1 to A25 affect the change temperatures ΔTeA1 to ΔTeA25 of the power storage units A1 to A25, respectively. This is because the portions of the power storage units A1 to A25 each transfer heat between adjacent portions. Further, most of this heat transfer occurs from a portion located inside the power storage unit 121 to a portion located outside. This is because the power storage unit 121 dissipates heat from the outer periphery.

  Therefore, the calculation unit 21 of the present embodiment calculates the change temperatures ΔTeA1 to ΔTeA25 in consideration of the mutual heat transfer effects of the heat generation amounts QA1 to QA25 of the power storage units A1 to A25. Specifically, the calculation unit 21 calculates the change temperatures ΔTeA1 to ΔTeA25 by performing a simulation based on the anisotropy of the thermal conductivity of the power storage unit 121 stored in the memory 22 using the calorific values QA1 to QA25. To do.

  Further, the change temperatures ΔTeA1 to ΔTeA25 are also affected by cooling by the fan 13. For this reason, the calculation unit 21 firstly absorbs the cooling air that has absorbed heat from the entire assembled battery 10 from the cooling state C of the intake air temperature and the discharge temperature of the cooling air flowing through the assembled battery 10 received from the cooling state detection unit 60. Calculate the amount of heat. Next, the endothermic amount for each secondary battery 100 is calculated by multiplying the endothermic amount from the entire assembled battery 10 by a coefficient that differs for each secondary battery 100. In the present embodiment, the coefficient that is different for each secondary battery 100 is set to a larger value in the assembled battery 10 as the secondary battery 100 closer to the air inlet 11. This is because the secondary battery 100 closer to the intake port 11 has a greater cooling effect by the cooling air. Then, the calculation unit 21 calculates the change temperatures ΔTeA1 to ΔTeA25 by performing a simulation in consideration of the heat absorption amount due to the cooling air together with the heat generation amounts QA1 to QA25 and the thermal conductivity anisotropy of the power storage unit 121.

  Next, a method for calculating the estimated voltage Ve will be described. Estimated voltage Ve is calculated from internal resistance R and current value I of power storage unit 121. Here, the internal resistance R of the power storage unit 121 is a combined resistance calculated by combining the internal resistances RA1 to RA25 of the power storage units A1 to A25 in parallel.

  Next, the computing unit 21 compares the temperature TA1 with the estimated temperature TeA1 (n) and determines whether or not these differences are within a predetermined allowable range (S104). Further, the voltage V and the estimated voltage Ve are compared, and it is determined whether or not these differences are also within a predetermined allowable range (S104).

  That is, when the difference between the estimated temperature TeA1 (n) and the actual temperature TA1 at least in the power storage unit A1 is large, all the estimated temperatures TeA1 (n) to TeA25 (n) are low in reliability. . For calculating the estimated voltage Ve, the internal resistance RA1 to the internal resistance RA25 used for calculating the estimated temperatures TeA1 (n) to TeA25 (n) are used. Therefore, by comparing the voltage V with the estimated voltage Ve, whether the values of the internal resistors RA1 to RA25 used for calculating the estimated temperatures TeA1 (n) to TeA25 (n) are highly reliable values. It can be determined whether or not. Based on these comparisons, it is determined whether all of the estimated temperatures TeA1 (n) to TeA25 (n) calculated in step S103 are highly reliable values.

  If at least one of the difference between the temperature TA1 and the estimated temperature TeA1 (n) and the difference between the voltage V and the estimated voltage Ve exceed the predetermined allowable range (S104: No), Correction according to these differences is performed (S105). Specifically, the values of the internal resistance RA1 to the internal resistance RA25, the heat absorption amount for each secondary battery 100 by the cooling air, the difference between the temperature TA1 and the estimated temperature TeA1 (n), and the difference between the voltage V and the estimated voltage Ve. Correction is performed by multiplying the coefficient according to. Then, the estimated temperatures TeA1 (n) to TeA25 (n) and the estimated voltage Ve are calculated again by using the corrected internal resistance RA1 to internal resistance RA25 and the endothermic amount. It should be noted that the coefficients used for correcting the internal resistance RA1 to the internal resistance RA25 and the endothermic amount in step S105 are values that fluctuate only when they need to be corrected. In step S103 in which these are first calculated, they are used as initial values. 1 is used. For this reason, this coefficient is not described in step S103.

  On the other hand, when the difference between the temperature TA1 and the estimated temperature TeA1 (n) and the difference between the voltage V and the estimated voltage Ve are within the predetermined allowable ranges (S104: Yes), Step S106 is performed. That is, it is determined that the reliability of all the estimated temperatures TeA1 (n) to TeA25 (n) calculated in step S103 is high.

  Next, the computing unit 21 determines whether any of the estimated temperatures TeA1 (n) to TeA25 (n) is within a predetermined allowable temperature (S106). When at least one of the estimated temperatures TeA1 (n) to TeA25 (n) exceeds the allowable temperature (S106: No), the calculation unit 21 drives the motor 14 by the cooling state control unit 70, and the fan 13 The assembled battery 10 is cooled by (S107). At this time, the vehicle ECU 80 is notified via the communication unit 23 that the internal temperature of the secondary battery 100 is higher than the allowable temperature. And vehicle ECU80 restrict | limits the electric current which flows through the assembled battery 10 so that the internal temperature of the secondary battery 100 may not rise any more (S107). That is, the vehicle ECU restricts charging / discharging of the assembled battery 10.

  When any of the estimated temperatures TeA1 (n) to TeA25 (n) is lower than the predetermined allowable temperature (S106: Yes), the calculation unit 21 transmits this information to the vehicle ECU 80 via the communication unit 23. And vehicle ECU80 in this case continues charging / discharging, without restrict | limiting the electric current which flows into the assembled battery 10. FIG.

  Thereafter, the calculation unit 21 stores the SOC (n) and the estimated temperatures TeA1 (n) to TeA25 (n) calculated in the nth time in the memory 22 (S108). Thus, the estimation of the internal temperature of the secondary battery 100 at the nth time is completed. In addition, the SOC (n) calculated at the nth time and the estimated temperatures TeA1 (n) to TeA25 (n) are stored in order to estimate the internal temperature of the secondary battery 100 at the next time (n + 1 time) after the next predetermined time t. Will be used.

  Next, a method of estimating the internal temperature of the secondary battery 100 by the secondary battery system 6 in the first time after charging / discharging is started will be described. The secondary battery system 6 also estimates the internal temperature of the secondary battery 100 in the same procedure as in the n-th method described above even at the first time when charging / discharging is started.

  However, in the first time when charging / discharging is started, the time (n-1) t is 0 because the time when charging / discharging is started is the same as the previous (n-1) time. . That is, the duration 0 s does not exist in the internal resistance map 200, and the internal resistance cannot be obtained using this. Therefore, in the first time, the duration 0.1 s of the internal resistance map 200 is used as a substitute value extremely close to the duration 0 s.

  Further, in the first time when charging / discharging is started, the previous SOC of the secondary battery 100 and the previous temperatures of the power storage units A1 to A25 calculated in the previous time before the predetermined time t do not exist. Therefore, in the first time when charging / discharging is started, the SOC of the secondary battery 100 calculated last at the time of the previous charging / discharging is used as the previous SOC.

  Further, even after the charging / discharging of the assembled battery 10 is completed, the secondary battery system 6 continues to calculate this until all the estimated temperatures of the power storage units A1 to A25 reach the same temperature as the environmental temperature. Therefore, when charging / discharging of the assembled battery 10 is started again during this period, the estimated temperature of the power storage units A1 to A25 immediately before is used as the previous temperature used for the first time.

  Then, after the previous charging / discharging is completed, if charging / discharging is started after all the temperatures of the power storage units A1 to A25 have reached the same temperature as the environmental temperature, the charging / discharging is performed as the previous temperature used for the first time. The temperature TA1 of the power storage unit A1 when the discharge is started is used. In this case, the internal temperature of the secondary battery 100 is uniform when charging / discharging is started. For this reason, the estimation of the internal temperature of the secondary battery 100 for the first time is started with the previous temperature of the power storage units A1 to A25 as the temperature TA1 of the power storage unit A1 when charging / discharging is started.

[Confirmation of effect]
The inventor confirmed the effect of the present invention by the following experiment. That is, an experiment was performed in which the secondary battery 100 for experiment was discharged alone, and the methods for estimating the internal temperature of the example and comparative examples 1 and 2 using different internal resistance maps were compared. The procedure of the method for estimating the internal temperature in the example and the comparative examples 1 and 2 is the same as the procedure of the method described above with reference to FIG. The only difference between the example and the comparative examples 1 and 2 is the internal resistance map used in step S103. Then, the voltage and the internal temperature were estimated by the method of estimating the internal temperature in Examples and Comparative Examples 1 and 2 using different internal resistance maps, and these were compared with the actually detected voltage and the actually detected temperature, respectively.

  In addition, in all initial conditions before the secondary battery 100 was discharged, the temperature was 0 ° C. and the SOC was 60%. Further, the secondary battery 100 was discharged at a current of 10 C at a C rate represented by the ratio of the current value (A) to the full charge capacity (Ah).

  Here, the internal resistance map used in Example 1 is an internal resistance map 200 (FIG. 5) showing all the relationships among the internal resistance, the duration, the SOC, and the temperature. On the other hand, in the first comparative example, the internal resistance map 300 showing only the relationship between the internal resistance and the SOC shown in FIG. 12 was used. That is, in the first comparative example, when the internal resistances of the power storage units A1 to A25 are determined, the duration and temperature change (portions indicated by dot hatching in FIG. 12) after the secondary battery 100 starts to be discharged are What was not considered was used. Moreover, in the comparative example 2, the internal resistance map 400 which showed only the relationship between internal resistance, duration, and SOC shown in FIG. 13 was used. That is, in Comparative Example 2, when the internal resistances of the power storage units A1 to A25 are obtained, changes in temperature after the secondary battery 100 starts to be discharged (portions indicated by dot hatching in FIG. 13) are not considered. Was used.

  The results of this experiment are shown in FIGS. FIG. 14 is a graph showing the relationship between duration and voltage in the experiment. FIG. 15 is a graph showing the relationship between the duration of the experiment and the internal temperature. In FIG. 14 and FIG. 15, the result of the example is indicated by a solid line, the result of Comparative Example 1 is indicated by a broken line, and the result of Comparative Example 2 is indicated by a one-dot chain line. The two-dot chain line indicates the measured voltage in FIG. 14 and the measured temperature in FIG.

  As shown in FIG. 14, the voltage estimated by Comparative Example 1 has a longer duration and is higher than the actually measured voltage. Further, the voltage estimated by the comparative example 2 is lower than the actually measured voltage as the duration time becomes longer. That is, the voltage estimated by Comparative Examples 1 and 2 has a longer duration and a larger error from the actually measured voltage. On the other hand, in the embodiment, even when the duration is long, a voltage close to the actually measured voltage is accurately estimated.

  Moreover, all the internal temperatures shown in FIG. 15 are the temperatures of the power storage unit A13. In this experiment, the temperature of the power storage unit A13 is compared because it is the most central part among the power storage units A1 to A25.

  The temperature near the surface of the power storage unit 121 can be estimated with relatively high accuracy even if the internal resistance map used is different. This is because the actual temperature is detected (temperature sensor 51) for a part of the surface of the power storage unit 121 (part of the power storage unit A1 in this embodiment), and correction is performed by comparing with the estimated temperature of the same part. Further, as shown in FIG. 11, the temperature difference between portions close to the surface of the power storage unit 121 is small.

  On the other hand, the difference from the actual temperature tends to increase as the estimated temperature is closer to the center of the power storage unit 121. This is because, as shown in FIG. 11, the temperature closer to the center of the power storage unit 121 has a larger difference from the surface temperature. Therefore, in this experiment, the temperature of the power storage unit A13 located at the center of the power storage unit 121 is compared.

  In the secondary battery 100 used in this experiment, a temperature sensor is attached to this portion in order to detect the actually measured temperature of the power storage unit A13. However, the temperature sensor 51 cannot be attached to the power storage unit A13 of the secondary battery 100 manufactured as a product. This is because the cost of the secondary battery 100 is significantly increased by attaching the temperature sensor to the power storage unit A13.

  And as shown in FIG. 15, the temperature estimated by the comparative example 1 is lower than measured temperature while the duration time becomes long. In addition, the temperature estimated by the comparative example 2 is longer than the actually measured temperature as the duration time becomes longer. That is, the temperature estimated by Comparative Examples 1 and 2 has a longer duration and an error from the actually measured temperature. On the other hand, in the embodiment, even if the duration is long, a temperature close to the actually measured temperature is accurately estimated.

  Therefore, it was found from this experiment that both the voltage and the internal temperature of the secondary battery can be accurately estimated by using an internal resistance map that shows all the relationships among the internal resistance, duration, SOC, and temperature. Further, it was found that, when the internal resistance map that does not take into account changes in the duration and temperature is used among the relationships between the internal resistance, duration, SOC, and temperature, these cannot be estimated with high accuracy. This is because internal resistance, duration, SOC, and temperature influence each other. That is, although not examined in this experiment, even when an internal resistance map that does not consider the change in SOC is used, it is naturally impossible to accurately estimate both the voltage and the internal temperature of the secondary battery.

  As described in detail above, the secondary battery system 6 of this embodiment includes the assembled battery 10 and the controller 20. In addition, the memory 22 of the controller 20 stores an internal resistance map 200 which is a relationship among the internal resistance, duration, SOC, and temperature of the secondary battery 100 acquired in advance using the AC impedance method. And the calculating part 21 calculates | requires the internal resistance of the part of electrical storage part A1-A25 which divided | segmented the electrical storage part 121 based on the internal resistance map 200 while charging / discharging of the assembled battery 10 is started. Furthermore, each calorific value of the power storage units A1 to A25 is calculated using the obtained internal resistance. In addition, a simulation based on the calculated heat generation amount, the anisotropy of the thermal conductivity of the power storage unit 121, and the heat absorption amount due to cooling is performed to calculate the estimated temperatures of the power storage units A1 to A25. Thereby, the temperature estimation method of the secondary battery which can estimate correctly each temperature of the part of electrical storage part A1-A25 which is the internal temperature of the secondary battery 100 is implement | achieved.

  Further, the vehicle ECU 80 of the present embodiment controls charging / discharging of the assembled battery 10 according to the internal temperature of the secondary battery 100 accurately estimated as described above, and further cools the assembled battery 10. Thereby, the control method of the secondary battery which can fully demonstrate the performance of the secondary battery 100 is implement | achieved.

  Note that this embodiment is merely an example, and does not limit the present invention. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, in the present embodiment, the present invention is applied to a lithium ion secondary battery, but the present invention can also be applied to other secondary batteries. Further, for example, in the present embodiment, the present invention is applied to a hybrid vehicle, but the present invention can also be applied to other vehicles such as a plug-in hybrid vehicle and an electric vehicle. For example, the present invention can be applied not only to a wound electrode body but also to a secondary battery having a stacked electrode body in which a negative electrode plate and a positive electrode plate are stacked without winding.

  For example, in the present embodiment, the predetermined time t, which is the time interval for estimating the internal temperature of the secondary battery 100, is described as 1 s, but the present invention is not limited to this. The predetermined time t may be within the range of the duration parameter of the internal resistance map prepared in advance. In the internal resistance map 200 of this embodiment, the range of 1 to 100 s is prepared at 1 s intervals. Therefore, when using the internal resistance map 200, the predetermined time t may be, for example, 2 s or 10 s.

  Further, for example, in the present embodiment, the temperature sensor 51 is attached only to the power storage unit A1 of the power storage unit 121 of the secondary battery 100, but this is not a limitation. That is, the temperature sensor 51 may be attached anywhere as long as it is the surface of the power storage unit 121. In this case, in step S104 of FIG. 10, the detected temperature of the portion where the temperature sensor 51 is attached may be compared with the estimated temperature. Two or more temperature sensors 51 may be attached to the surface of the power storage unit 121. In this case, the accuracy of the estimated temperature can be further increased.

  Further, for example, in this embodiment, the temperature sensor 51 is attached to the power storage unit A1 of all the secondary batteries 100 constituting the assembled battery 10. And although the internal temperature of the secondary battery 100 is each correct | amended based on the temperature TA1 detected about the part of electrical storage part A1, it is not restricted to this. In the assembled battery, the tendency of the temperature distribution of the secondary battery constituting the battery can be acquired in advance by experiments or the like. Specifically, in the assembled battery 10 of this embodiment, cooling air is taken in from the intake port 11 and discharged from the discharge port 12. For this reason, the secondary battery 100 located closer to the air inlet 11 tends to become colder. If this tendency can be specifically obtained, only the temperature TA1 of the power storage unit A1 portion of at least one secondary battery 100 among the secondary batteries 100 constituting the assembled battery 10 may be detected. This is because other secondary batteries 100 can be corrected based on the temperature TA1.

DESCRIPTION OF SYMBOLS 100 ... Secondary battery 120 ... Electrode body 121 ... Power storage part 200 ... Internal resistance map

Claims (9)

In the secondary battery temperature estimation method,
A secondary battery including an electrode body having a power storage unit in which a positive electrode plate and a negative electrode plate are stacked via a separator,
Acquired using the alternating current impedance method, the internal resistance of the secondary battery, the duration from the start of charging / discharging of the secondary battery, and the remaining battery capacity relative to the fully charged battery capacity of the secondary battery An internal resistance map that is a relationship between the SOC that is the ratio of the above and the temperature of the power storage unit is prepared in advance,
At the time when charging and discharging of the secondary battery is started and dividing the duration in advance,
Determining the internal resistance of the power storage unit based on the internal resistance map;
The calorific value of the electricity storage unit is calculated using the obtained internal resistance,
A temperature estimation method for a secondary battery, wherein an estimated temperature of the power storage unit at a time when charging and discharging of the secondary battery is continued is calculated using the calculated calorific value. The temperature estimation method for a secondary battery according to claim 1,
A plurality of partial areas are defined by dividing the power storage unit into a plurality of width directions and thickness directions, respectively.
Determining the internal resistance of the power storage unit for each of the plurality of parts of the power storage unit;
Calculating the heat generation amount of the power storage unit for each of a plurality of portions of the power storage unit;
The estimated temperature of the power storage unit is further divided for each of the plurality of parts of the power storage unit,
A temperature estimation method for a secondary battery, wherein the temperature is calculated by performing a simulation based on different thermal conductivities in a width direction and a thickness direction of the power storage unit. In the temperature estimation method of the secondary battery of Claim 2,
A detected temperature detected from at least a first portion of the plurality of portions of the power storage unit, an estimated temperature of the first portion, and
The detected voltage detected from the secondary battery is compared with the estimated voltage calculated from the internal resistance obtained using the internal resistance map, respectively.
If at least one of the difference between the detected temperature and the estimated temperature of the first part and the difference between the detected voltage and the estimated voltage of the secondary battery exceeds a predetermined allowable range, the difference In accordance with the internal resistance map, the internal resistance for each of the plurality of portions of the power storage unit, the difference between the detected temperature of the first portion and the estimated temperature, and the detected voltage of the secondary battery A method for estimating the temperature of a secondary battery, wherein a correction is made so that any difference between the estimated voltage and the estimated voltage is within the allowable range. In the secondary battery temperature estimation method according to claim 3,
Recalculating the estimated temperature and the estimated voltage for each of the plurality of parts of the power storage unit using the corrected internal resistance for each of the plurality of parts of the power storage unit, . In the temperature estimation method of the secondary battery as described in any one of Claim 2 to Claim 4,
Targeting a battery equipped with a cooling device as the secondary battery,
Further, the estimated temperature for each of the plurality of portions of the power storage unit,
A temperature estimation method for a secondary battery, wherein the temperature is calculated by performing a simulation based on an amount of heat absorbed from the secondary battery by the cooling device. The temperature estimation method for a secondary battery according to claim 5,
Comparing the detected temperature detected from at least the first portion located on the surface of the plurality of portions of the power storage unit with the estimated temperature of the first portion;
When the difference between the detected temperature of the first part and the estimated temperature exceeds a predetermined allowable range, the endothermic amount is determined according to the difference between the detected temperature of the first part and the estimated temperature. A temperature estimation method for a secondary battery, wherein the difference is corrected so as to be within the allowable range. The temperature estimation method for a secondary battery according to claim 6,
A temperature estimation method for a secondary battery, wherein the estimated temperature for each of the plurality of portions of the power storage unit is calculated again based on the corrected endothermic amount. In the control method of the secondary battery which controls the said secondary battery based on the estimated temperature of the said electrical storage part computed by the temperature estimation method of the secondary battery as described in any one of Claim 1- Claim 7 ,
A control method for a secondary battery, wherein a current flowing through the secondary battery is limited when an estimated temperature of the power storage unit is higher than a predetermined temperature. In the control method of the secondary battery which controls the said secondary battery based on the estimated temperature of the said electrical storage part computed by the temperature estimation method of the secondary battery as described in any one of Claim 5-7 ,
When the estimated temperature of the power storage unit is higher than a predetermined temperature, the cooling state of the cooling device is controlled so that the cooling effect of the secondary battery is increased. .

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