JP2018147680A - Temperature abnormality determination device, temperature abnormality determination method, and computer program - Google Patents

Abstract

A temperature abnormality determination device, a temperature abnormality determination method, and a computer program are provided. A temperature abnormality determination device for determining whether or not a temperature of a secondary battery is abnormal, comprising a thermal resistance value based on a thermal circuit model of the secondary battery and ambient air of the secondary battery, and A first temperature estimating unit for estimating a first internal temperature of the secondary battery using a surface temperature of the secondary battery and an ambient temperature, and the secondary battery based on an internal resistance value of the secondary battery. A second temperature estimation unit that estimates the second internal temperature, and a determination unit that determines whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature; Is provided. [Selection] Figure 2

Description

  The present invention relates to a temperature abnormality determination device, a temperature abnormality determination method, and a computer program using a temperature obtained by estimating an internal temperature of a secondary battery.

  The secondary battery is connected to a processing device that performs processing related to charge management, and the processing device processes information on the state of charge (SOC) and the state of health (SOH) of the secondary battery. To do. Here, SOC and SOH are values that cannot be directly measured, and are estimated using measurable information such as the voltage, current, and temperature of the secondary battery. Regarding the temperature within the measurable information, although the temperature inside the battery is originally required but cannot be measured, the surface temperature of one or more locations of the secondary battery is measured, and the surface temperature and resistance value are measured. The internal temperature is estimated from

  As an estimation method of the internal temperature of the secondary battery, for example, in Patent Document 1, the internal temperature is determined by using a predetermined internal / external temperature difference ratio from the surface temperature according to the operating state of the cooling fan used as a cooling mechanism toward the surface of the secondary battery. A method for estimating temperature is disclosed. Specifically, in Patent Document 1, the surface temperature and the ambient temperature of the battery are measured, and the internal temperature is estimated using the measurement result and the internal / external temperature difference ratio that varies depending on the output of the cooling fan.

  Patent Document 2 discloses a method for improving estimation accuracy by adding a function of diagnosing correctness of an estimation result when estimating an internal temperature based on a surface temperature and a wind speed from a cooling fan. In Patent Document 2, the internal temperature is estimated by using a unique characteristic obtained from the relationship between the surface temperature, the ambient temperature, and the wind speed and the actually measured internal temperature, and back-calculated from the measured surface temperature, the ambient temperature, and the wind speed. It is done. The correctness / incorrectness is determined because the surface temperature and the internal temperature coincide with each other within a predetermined range for a certain period from the start-up, and therefore the internal resistance value estimated in this period is determined as the internal temperature (= surface temperature) at that time. Are recorded in association with each other and used as a table. When the estimated internal temperature matches the recorded internal temperature after the period when the surface temperature and internal temperature match, the internal resistance value in that case is estimated and associated with the matched internal temperature The estimated temperature is determined to be abnormal when it does not match the stored internal resistance value. It is used that the internal resistance values should match when the internal temperatures match.

International Publication No. 2011-045853 Japanese Patent Laid-Open No. 9-245846

  The internal temperature can be estimated by the method disclosed in Patent Document 1. However, as disclosed in Patent Document 1, the measurement results of the surface temperature and the ambient temperature and the output of the cooling fan are used for the estimation. The measurement result and the output of the cooling fan may include noise and the like. Due to these effects, the estimation result may include a large error, and a temperature abnormality may be erroneously determined.

  On the other hand, Patent Document 2 discloses a function of diagnosing correctness / incorrectness with respect to the estimated temperature. In the method of Patent Document 2, when the temperature is relatively low, such as a period immediately after startup, it is possible to diagnose an abnormality in the estimated internal temperature value and thereby estimate the temperature with high accuracy. However, in a relatively low temperature range, a change in temperature and a change in electrical internal resistance value are linearly related. However, in a relatively high range above room temperature, the change in internal resistance value is small with respect to the temperature change. Therefore, the abnormality diagnosis based on the internal resistance value may cause a decrease in diagnosis accuracy. The secondary battery deteriorates depending on the number of times it reaches a high temperature state, and the higher the temperature is, the more the deterioration is promoted. Therefore, temperature control such as how much temperature is allowed to be charged becomes more important as the temperature is higher. Therefore, in order to estimate the temperature inside the battery, high accuracy is desired regardless of the temperature range, even if the temperature is high. In addition, in the method disclosed in Patent Document 2, a relationship table between the internal resistance value and temperature necessary for diagnosis must be created after activation, which requires computational resources and storage resources. Furthermore, in the method disclosed in Patent Document 2, since the temperature is still diagnosed using the internal resistance value, the fluctuation error and the measurement error of the internal resistance affect the determination of whether the temperature is correct or incorrect.

  Accordingly, the present disclosure provides a temperature abnormality determination device, a temperature abnormality determination method, and a computer program that can determine whether or not the internal temperature is abnormal while using the estimated value of the internal temperature of the battery. With the goal.

  A temperature abnormality determination device according to the present disclosure is a temperature abnormality determination device that determines whether or not a temperature of a secondary battery is abnormal, and is based on a thermal circuit model of the secondary battery and ambient air of the secondary battery. Based on a thermal resistance value, a first temperature estimation unit that estimates a first internal temperature of the secondary battery using the surface temperature and ambient temperature of the secondary battery, and an internal resistance value of the secondary battery A second temperature estimation unit for estimating a second internal temperature of the secondary battery, and whether the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature. A determination unit for determining.

  A temperature abnormality determination method of the present disclosure is a temperature abnormality determination method for determining whether or not a temperature of a secondary battery is abnormal, and is based on a thermal circuit model of the secondary battery and the ambient air of the secondary battery. A first internal temperature of the secondary battery is estimated using a thermal resistance value, a surface temperature of the secondary battery, and an ambient temperature, and the secondary battery is estimated based on the internal resistance value of the secondary battery. A second internal temperature is estimated, and a process of determining whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature is executed.

  A computer program of the present disclosure is a computer program that causes a computer to determine whether or not a temperature of a secondary battery is abnormal, and is based on a thermal circuit model of the secondary battery and the ambient air of the secondary battery. A first internal temperature of the secondary battery is estimated using a resistance value, a surface temperature of the secondary battery, and an ambient temperature, and the secondary battery's first temperature is estimated based on the internal resistance value of the secondary battery. 2 is estimated, and whether or not the temperature of the secondary battery is abnormal is determined using the first internal temperature and the second internal temperature.

  According to the present disclosure, it is possible to more accurately determine whether or not the internal temperature of the battery is abnormal.

It is a schematic diagram which shows the structure of the vehicle power supply system containing a vehicle-mounted secondary battery and a battery monitoring apparatus. It is a block diagram which shows an example of a structure of the battery monitoring apparatus in this Embodiment. It is a thermal circuit diagram which shows typically the example of a thermal circuit model application to the secondary battery unit in this Embodiment. It is a graph which shows an example of the relationship between an applied voltage and an air thermal resistance value. It is explanatory drawing which shows an example of the equivalent circuit of a secondary battery unit. It is a schematic diagram which shows the impedance characteristic of a secondary battery unit. It is explanatory drawing which shows the example of the content of the waiting time T corresponding to a boundary frequency range. It is a graph which shows the correspondence of internal resistance value R and internal temperature. It is a graph which shows transition of the internal temperature Tinb estimated by the 2nd internal temperature estimation part. It is a flowchart which shows an example of the process sequence by a battery monitoring apparatus. It is a flowchart which shows an example of the process sequence of a temperature abnormality determination process. It is a flowchart which shows another example of the process sequence of a temperature abnormality determination process. It is a flowchart which shows another example of the process sequence of a temperature abnormality determination process.

[Description of Embodiment of Present Invention]

  The temperature abnormality determination device according to the present embodiment is a temperature abnormality determination device that determines whether or not the temperature of the secondary battery is abnormal, and is a thermal circuit of the secondary battery and the ambient air of the secondary battery. A first temperature estimation unit for estimating a first internal temperature of the secondary battery using a thermal resistance value based on the model, a surface temperature of the secondary battery, and an ambient temperature; and an internal resistance of the secondary battery Whether the temperature of the secondary battery is abnormal using the second temperature estimation unit that estimates the second internal temperature of the secondary battery based on the value, and the first internal temperature and the second internal temperature A determination unit for determining whether or not.

  The temperature abnormality determination method according to the present embodiment is a temperature abnormality determination method for determining whether or not the temperature of the secondary battery is abnormal, and is a thermal circuit of the secondary battery and the ambient air of the secondary battery A first internal temperature of the secondary battery is estimated using a thermal resistance value based on the model, a surface temperature of the secondary battery, and an ambient temperature, and the second internal battery is based on the internal resistance value of the secondary battery. A second internal temperature of the secondary battery is estimated, and it is determined whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature.

  The computer program according to the present embodiment is a computer program for causing a computer to determine whether or not the temperature of the secondary battery is abnormal, and is a thermal circuit model of the secondary battery and the ambient air of the secondary battery. The first internal temperature of the secondary battery is estimated using the thermal resistance value based on the surface temperature and the ambient temperature of the secondary battery, and the secondary battery is based on the internal resistance value of the secondary battery. A second internal temperature of the battery is estimated, and a process of determining whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature is executed.

  The first temperature estimation unit is based on the concept of heat flow radiated toward the outside of the secondary battery, and the temperature difference between the surface temperature and the internal temperature and the temperature difference between the surface temperature and the ambient temperature are respectively The internal temperature is calculated backward from the value obtained from the thermal resistance value of the secondary battery and the thermal resistance value of the ambient air. Since the temperature difference between the surface temperature and the internal temperature is indefinite depending on the temperature range, the accuracy is improved by back calculation using the thermal resistance value.

  The second temperature estimator is based on the fact that the internal resistance value and the internal temperature have a correlation because the heat generation of the secondary battery is caused by Joule heat generation due to the internal electrical resistance during charging and discharging. To estimate the internal temperature. The internal resistance value can be calculated from the voltage value and current value of the secondary battery.

  A determination part determines whether it is abnormal using the internal temperature estimated by the 1st temperature estimation part and the 2nd temperature estimation part. Since the internal temperature does not necessarily match the surface temperature, it cannot be simply derived from the surface temperature, and it is difficult to actually measure during operation of the secondary battery, but it can be estimated by different methods. became. When the internal temperature is estimated by one method, the estimation result may be greatly affected by the error of the measurement value used in the estimation process, but the different internal temperatures estimated by different methods It is possible to make a determination without being affected by a specific error by the processing such as comparing with. The pros and cons of the estimated temperature by different methods can be compensated for each other, and the abnormality determination accuracy can be improved.

  In the temperature abnormality determination device according to the present embodiment, the determination unit interrupts determination when the difference between the first internal temperature and the second internal temperature is equal to or greater than a predetermined threshold.

  When there is a divergence between the first internal temperature and the second internal temperature estimated by different methods, there is a high possibility that one of the estimation accuracy is poor. However, since it is difficult to determine whether the estimation accuracy is good or not, the determination unit does not determine whether there is an abnormality using the estimated internal temperature. Accordingly, it is possible to avoid processing such as making an erroneous determination using an internal temperature that is erroneously estimated to be excessively high or low.

  In the temperature abnormality determination device according to the present embodiment, the determination unit determines whether the difference is equal to or smaller than a second threshold value that is smaller than the predetermined threshold value, and is equal to or smaller than the second threshold value. If it is determined, it is determined whether a maximum value of the first internal temperature and the second internal temperature is within a predetermined range. If it is determined that the maximum value is outside the predetermined range, the secondary battery Is determined to be abnormal.

  When it can be determined that the difference between the first internal temperature and the second internal temperature estimated by different methods is very small, it can be estimated that the estimation accuracy of these internal temperatures is high. Therefore, the determination unit determines whether the temperature is abnormal using the estimated internal temperature. Moreover, by determining whether the temperature is abnormal (high temperature) at the maximum value of the first internal temperature and the second internal temperature, the abnormality is determined on the safety side, and a secondary battery is recommended. It is possible to more reliably avoid going out of the temperature range.

  The temperature abnormality determination device according to the present embodiment further includes a surface temperature acquisition unit that acquires the surface temperature of the secondary battery, and the determination unit is one of the first internal temperature and the second internal temperature. If at least one is lower than the surface temperature acquired by the surface temperature acquisition unit, the determination is interrupted.

  The surface temperature acquisition unit acquires the surface temperature of the secondary battery. When the secondary battery is composed of a plurality of cells, the temperature measured at each of the plurality of cells or at one or several appropriate points may be acquired.

  If any of the estimated different internal temperatures is lower than the surface temperature, it is assumed that the estimation accuracy of the internal temperature is low, so the determination unit determines whether there is an abnormality using the estimated internal temperature. Don't do it. Although the internal temperature does not necessarily match the surface temperature, the estimated internal temperature is often higher than the surface temperature except during a limited period such as during discharge and immediately after switching between charge and discharge. When the temperature is lower than the surface temperature, it can be estimated that the estimation accuracy is low.

  In the temperature abnormality determination device according to the present embodiment, the determination unit has a difference between the first internal temperature and the second internal temperature that is less than a predetermined threshold, and the first internal temperature and the second internal temperature. When the minimum value of the internal temperature is equal to or higher than the surface temperature, it is determined whether the maximum value of the first internal temperature and the second internal temperature is within a predetermined range, and is outside the predetermined range. When it is determined that the temperature of the secondary battery is abnormal.

  When it can be determined that the difference between the first internal temperature and the second internal temperature estimated by different methods is very small, it can be estimated that the estimation accuracy of these internal temperatures is high. Therefore, the determination unit determines whether or not the temperature is abnormal using the estimated internal temperature. Furthermore, since the internal temperature is often higher than the surface temperature except for a limited period, the determination is made after confirming the estimated accuracy based on whether or not the estimated internal temperature is higher than the surface temperature. Thereby, it is possible to avoid determination due to an erroneous estimated temperature and to increase the determination accuracy.

  In the temperature abnormality determination device according to the present embodiment, a voltage acquisition unit that acquires the voltage of the secondary battery, a current acquisition unit that acquires the current of the secondary battery, and a predetermined impedance spectrum of the secondary battery A specifying unit for specifying a standby time based on a boundary frequency region in which a diffusion impedance caused by a diffusion process of ions contributes to an impedance of the secondary battery, and the voltage acquisition unit at a switching timing of charging / discharging of the secondary battery And an internal resistance calculation unit that calculates an internal resistance value using a voltage value and a current value acquired by the current acquisition unit, respectively, and a voltage value and a current value acquired after the standby time from the timing, and the two A storage unit that stores in advance the correspondence between the internal resistance value of the secondary battery and the temperature; and the second temperature estimation unit is configured to control the internal resistance value calculated by the internal resistance calculation unit. The temperature at which the reference from the storage unit, estimates the temperature and the second internal temperature.

  The internal resistance calculation unit estimates the internal resistance using a voltage value and a current value measured before switching between charge and discharge and a voltage value and a current value measured after the standby time. Even in cases where secondary battery charge / discharge switching is frequently repeated, it is possible to accurately estimate the internal resistance value from the impedance that is not affected by the diffusion impedance resulting from the ion diffusion process after the switching. It is.

  The storage unit stores the correspondence between the internal resistance value and the temperature in advance. For example, it is good to memorize | store the response | compatibility with the measured internal resistance value and internal temperature about the used secondary battery. It is possible to increase the accuracy of the estimated internal temperature as long as the correspondence relationship matches the characteristics of each secondary battery.

  The second internal temperature estimation unit estimates the temperature corresponding to the internal resistance value accurately estimated as the second internal temperature with reference to the storage unit. The second internal temperature estimation unit can accurately estimate the internal temperature from the corresponding temperature in accordance with the characteristics of each secondary battery.

  The temperature abnormality determination device according to the present embodiment further includes a charging rate acquisition unit that acquires the charging rate of the secondary battery, and the storage unit differs in correspondence between the internal resistance value of the secondary battery and the temperature. The second temperature estimating unit stores the temperature corresponding to the internal resistance value in the charging rate acquired by the charging rate acquiring unit using the internal resistance value calculated by the internal resistance calculating unit. Reference is made from the storage unit.

  The charging rate acquisition unit may calculate the charging rate based on the calculated internal resistance value, or may acquire the charging rate from another measurement unit or calculation unit.

  The storage unit stores the correspondence between the internal resistance value of the secondary battery and the temperature for each charging rate. Since the correspondence relationship between the internal resistance value and the temperature differs depending on the charging rate, the second internal temperature estimation accuracy by the second internal temperature estimation unit can be increased by referring to the temperature from the correspondence relationship corresponding to the acquired charging rate. Can be improved.

[Details of the embodiment of the present invention]
Hereinafter, a temperature abnormality determination device according to the present invention will be described with reference to the drawings showing embodiments. In the following embodiment, it is arranged in a vehicle equipped with a secondary battery, and not only as a temperature abnormality determination device according to the present invention, but also obtains various measured values related to the secondary battery to obtain SOC or SOH. A battery monitoring device that functions as a device for processing such information will be described as an example.

  FIG. 1 is a schematic diagram showing a configuration of a vehicle power supply system including an in-vehicle secondary battery and a battery monitoring device 100. In addition to the battery monitoring device 100, the vehicle power supply system includes a secondary battery unit 50, relays 61 and 63, a generator (ALT) 62, a starter motor (ST) 64, a battery 65, and an electric load 66.

  The secondary battery unit 50 uses, for example, a lithium ion battery, and a plurality of cells 51 are connected in series or in series and parallel and accommodated in a casing. The casing is provided with a cooling mechanism 56 for cooling the cell 51. The cooling mechanism 56 includes, for example, an air cooling fan provided in the housing and an exhaust port provided at a position as far as possible from a place where the air cooling fan is installed. The cooling mechanism 56 blows air in the housing at a different number of revolutions per unit time according to different applied voltages based on a control signal from the battery monitoring device 100. The cooling mechanism 56 is not limited to an air cooling fan.

  Further, the secondary battery unit 50 includes a voltage sensor 52, a current sensor 53, a first temperature sensor 54, and a second temperature sensor 55 in the housing.

  The voltage sensor 52 detects the voltage of each cell 51 and the voltage between both ends of the secondary battery unit 50 and outputs the detected voltage to the battery monitoring apparatus 100 via the voltage detection line 50a. The current sensor 53 is composed of, for example, a shunt resistor or a hall sensor, and detects the charging current and discharging current of the secondary battery. The current sensor 53 outputs the detected current to the battery monitoring device 100 via the current detection line 50b.

  The first temperature sensor 54 is composed of, for example, a thermistor, and detects the surface temperature at any one or a plurality of locations of the plurality of cells 51. One first temperature sensor 54 may be provided for each cell 51. The first temperature sensor 54 outputs the detected surface temperature to the battery monitoring device 100 via the first temperature detection line 50c. When each of the surface temperatures of the plurality of cells 51 is detected, the temperature is output from each of the plurality of temperature detection lines 50c. The second temperature sensor 55 is composed of, for example, a thermistor, and detects the temperature inside the casing, that is, the ambient temperature of the cell 51. The second temperature sensor 55 outputs the detected ambient temperature to the battery monitoring device 100 via the second temperature detection line 50d. Note that the second temperature sensor 55 may also be provided at a plurality of locations in the housing.

  The battery 65 is, for example, a lead battery, and supplies power to various electric loads 66 mounted on the vehicle, and supplies power to drive the starter motor 64 when the relay 63 is on. The generator 62 generates electric power by the rotation of the vehicle engine, and outputs direct current by an internal rectifier circuit to charge the battery 65. The generator 62 charges the battery 65 and the secondary battery unit 50 when the relay 61 is on. The relays 61 and 63 are turned on and off by a relay control unit (not shown).

  FIG. 2 is a block diagram showing an example of the configuration of the battery monitoring apparatus 100 in the present embodiment. FIG. 2 shows a configuration related to a function as a battery temperature abnormality determination device among the functions executed by the battery monitoring device 100, and illustration and detailed description of the other configurations are omitted. The battery monitoring device 100 includes a control unit 10, a storage unit 11, a timer 12, a voltage acquisition unit 13, a current acquisition unit 14, a surface temperature acquisition unit 15, an ambient temperature acquisition unit 16, a first internal temperature estimation unit 17, and a standby time specification. Unit 18, internal resistance calculation unit 19, second internal temperature estimation unit 20, temperature abnormality determination unit 21, open circuit voltage calculation unit 22, state of charge (SOC) calculation unit 23, health state (SOH) calculation unit 24, and output unit 25. The processing of the voltage acquisition unit 13 to the health state calculation unit 24 (particularly the first internal temperature estimation unit 17 and the second internal temperature estimation unit 20 to the health state calculation unit 24) is executed by the control unit 10 with software. Each of these processes may be executed as an integrated circuit, or a part thereof may be executed as an integrated circuit, and the remaining part may be executed by a process based on software of the control unit 10. Good.

  The control unit 10 uses one or a plurality of processors and a memory, executes processing for controlling each component, and exhibits a function as a temperature abnormality determination device. The storage unit 11 stores data and the like referred to by the control unit 10 using a nonvolatile memory such as a flash memory. The timer 12 outputs a pulse signal at a predetermined frequency, and the control unit 10 can count time by counting the pulses of the signal output from the timer 12. For example, the control unit 10 sequentially executes processing by each component described below at a constant sampling period such as 10 milliseconds, and performs temperature abnormality determination, charge state calculation, and health state calculation. The control unit 10 can control this sampling period.

  The voltage acquisition unit 13 acquires the voltage value V of the voltage of the secondary battery unit 50 (for example, the voltage across the secondary battery unit 50) via the voltage detection line 50a. The current acquisition unit 14 acquires the current value I of the current (charging current or discharging current) of the secondary battery unit 50 via the current detection line 50b.

  The surface temperature acquisition unit 15 acquires the value of the surface temperature of the cell 51 of the secondary battery unit 50 via the first temperature detection line 50c. The ambient temperature acquisition unit 16 acquires the temperature inside the casing of the secondary battery unit 50, that is, the value of the ambient temperature of the cell 51 via the second temperature detection line 50d.

  Each time the first internal temperature estimation unit 17 acquires the surface temperature value Ts by the surface temperature acquisition unit 15 and the ambient temperature acquisition unit 16 acquires the ambient temperature value Ta, the first internal temperature estimation unit 17 uses these two measurement values. The internal temperature Tina of the secondary battery unit 50 is estimated and calculated. Specifically, the first internal temperature estimation unit 17 is obtained using the two measured values Ts and Ta and the values of the thermal resistances of the cell 51 and the ambient air that are obtained in advance and stored in the storage unit 11. The internal temperature Tina is estimated and calculated from the calorific value. Note that the value of the thermal resistance of the ambient air varies depending on the operating state of the cooling mechanism 56. Therefore, the first internal temperature estimating unit 17 appropriately selects from the storage unit 11 the value of the thermal resistance when calculating the internal temperature Tina by acquiring the control signal to the cooling mechanism 56 or the state signal from the cooling mechanism 56. Use. Details of the processing by the first internal temperature estimation unit 17 will be described later.

  The standby time specifying unit 18 specifies the standby time T for the internal resistance calculation unit 19 to calculate the internal resistance value R. The waiting time T is until the impedance of the cell 51 as a whole can ignore the influence of the diffusion impedance of ions in the cell 51 in view of the impedance characteristics of the cell 51 (see FIG. 6). This is the elapsed time from the charge / discharge switching time. Since the standby time T varies depending on the characteristics and the charging rate (SOC) of each battery, each secondary battery unit 50 is stored in advance in the storage unit 11 in association with the charging rate as shown in FIG. deep. The standby time specifying unit 18 reads and uses the standby time T corresponding to the charging rate calculated by the charging state calculation unit 23 most recently.

  The internal resistance calculation unit 19 calculates the internal resistance R at the timing when the control unit 10 determines that charging / discharging has been switched by the relay 61 based on the polarity of the current detected by the current acquisition unit 14. When it is determined that there is switching, the internal resistance calculation unit 19 sets the voltage value V acquired by the voltage acquisition unit 13 immediately before that as the voltage value Vb at the time of switching, and the current value I acquired by the current acquisition unit 12 The current value Ib at the time of switching is stored in the memory. The internal resistance calculation unit 19 further sets the voltage value V acquired by the voltage acquisition unit 11 after the standby time T specified by the standby time specification unit 18 after determining that the switching has been made as the voltage value Vc after the standby time T. Similarly, the current value I acquired by the current acquisition unit 12 after the standby time T is stored in the memory as the current value Ic after the standby time T, respectively. The internal resistance calculator 19 calculates the internal resistance value R of the secondary battery unit 50 using the voltage values Vb and Vc and the current values Ib and Ic stored in the memory.

  The second internal temperature estimation unit 20 uses the latest charge rate stored and the internal resistance value R calculated by the internal resistance calculation unit 19, and stores the internal resistance value stored in advance in the storage unit 11 for each charge rate. The internal temperature Tinb is estimated by referring to a table showing the correspondence with the internal temperature (see FIG. 8). Details of the processing in the second internal temperature estimation unit 20 will be described later.

  The temperature abnormality determination unit 21 acquires the internal temperature Tina estimated by the first internal temperature estimation unit 17, the internal temperature Tinb estimated by the second internal temperature estimation unit 20, and the surface temperature acquisition unit 15 as necessary. Using the surface temperature Ts thus determined, an abnormality (excessively high temperature) in the internal temperature of the secondary battery unit 50 is determined. When the abnormality is determined, the control unit 10 is notified, and thereby the control unit 10 executes various processes. Details of the processing by the temperature abnormality determination unit 21 will be described later.

  Based on the resistance value R of the internal resistance calculated by the internal resistance calculation unit 19, the voltage value V acquired by the voltage acquisition unit 11, and the current value I acquired by the current acquisition unit 14, the open circuit voltage calculation unit 22 The open circuit voltage of the battery unit 50 is calculated. When the open voltage of the secondary battery is represented by OCV (Open Circuit Voltage), it can be calculated by OCV = V−Vo. Here, Vo is an overvoltage, which is a voltage value obtained by adding a polarization voltage to a voltage represented by resistance value R × current value I of the internal resistance.

  The charging state calculation unit 23 calculates the charging rate of the secondary battery unit 50 based on the open circuit voltage OCV calculated by the open circuit voltage calculation unit 22. For example, by setting a correlation between the open circuit voltage OCV of the secondary battery unit 50 and the charging rate in advance, an estimated value of the charging rate of the secondary battery unit 50 can be calculated based on the calculated open circuit voltage OCV. . Further, the charge state calculation unit 23 calculates the charge amount of the secondary battery unit 50 (the ratio of the charged capacity to the full charge capacity, that is, the charge rate) by accumulating the current value I acquired by the current acquisition unit 14. May be. Current integration is the integration of current over time. For example, if the sampling period for current acquisition is Δt, the current value acquired each time sampling is Ibi (i = 1, 2,...) The integration is calculated by ΣIbi × Δt (i = 1, 2,...). If the most recently determined charge rate is variable SOCin and the first charge amount is SOC1, the first charge amount SOC1 is SOC1 = SOCin ± {ΣIbi × Δt (i = 1, 2,...) / Full charge capacity FCC. } Can be calculated by the following formula. Regarding ±, + (plus) corresponds to charging and − (minus) corresponds to discharging.

  The health state calculation unit 24 calculates the health state (SOH) of the secondary battery based on the ratio of the resistance value R calculated by the internal resistance calculation unit 19 to the initial value R0 for the internal resistance of the secondary battery unit 50.

  The output unit 25 is an interface that outputs a value calculated or estimated by each component to the outside of the battery monitoring device 100. For example, the output unit 25 is a communication interface connected to the in-vehicle network. The output unit 25 may be an interface connected to a display unit for a driver such as an instrument panel or an OHD (Over Head Display).

  The control unit 10 performs processing related to battery management using the charging rate SOC of the secondary battery unit 50 calculated by controlling each component unit, the health state SOH, or the determination result by the temperature abnormality determination unit 21. When the charging rate SOC is equal to or less than a predetermined value, the control unit 10 performs processing such as indicating the calculated charging rate with a warning light from the output unit 25 connected to the instrument panel. In addition, when the health state SOH is below a predetermined degree, even when the determination result by the temperature abnormality determination unit 21 is abnormal, processing such as issuing a warning with a warning lamp is performed. Then, in order to use the secondary battery unit 50 within a predetermined temperature range, the control unit 10 turns off the secondary 61 by shutting off the relay 61 or the like when the abnormality is determined by the temperature abnormality determination unit 21 during charging / discharging. The battery unit 50 is protected. Moreover, the control part 10 may be made to transmit the determination result by the charging rate SOC, the health state SOH, or the temperature abnormality determination part 21 from the output part 25 which is a communication part to other apparatuses in the vehicle. You may make it transmit to the apparatus outside a vehicle further from the other apparatus in a vehicle. In these external devices, processing is performed based on the determination result by the charging rate SOC, the health state SOH, or the temperature abnormality determination unit 21 transmitted from the battery monitoring device 100.

  Regarding the internal temperature abnormality determination processing by the battery monitoring device 100, first, the estimation methods of the internal temperatures Tina and Tinb used by the temperature abnormality determination unit 21 will be described in detail.

  First, a method for estimating the internal temperature Tina by the first internal temperature estimation unit 17 will be described. As described above, the first internal temperature estimation unit 17 includes the two measured values of the surface temperature value Ts of the cell 51 of the secondary battery unit 50 and the ambient temperature value Ta of the cell 51, the cell 51 and The internal temperature Tina is calculated from the calorific value obtained using the value of the thermal resistance of each ambient air. It should be noted here that the value of thermal resistance is used. The thermal resistance represents the behavior of the secondary battery unit 50 in consideration of not only the Joule heat due to the internal resistance to the applied voltage and current but also the entropy heat generated due to the chemical reaction as a factor of heat generation in the secondary battery unit 50. Can do.

  FIG. 3 is a thermal circuit diagram schematically showing an application example of the thermal circuit model to the secondary battery unit 50 in the present embodiment. The thermal circuit is expressed that the amount of heat Qall is given to a terminal connected to a predetermined heat source (ground) via the heat capacity Cin of the secondary battery unit 50. The amount of heat Qall given to the secondary battery unit 50 is stored in the heat capacity Cin of the secondary battery unit 50 itself, and part (Qout) is transmitted to the surface via the thermal resistance Rin, and the heat of the surrounding air It is expressed that the heat is radiated through the resistor Ra and further transmitted to a predetermined heat source (ground) through the outer casing or the like.

  The calorific value Qall of the secondary battery unit 50 is represented by the sum of the calorific value Qp (formula 1) due to Joule heat and the calorific value Qs (formula 2) due to entropy heat (formula 3). Here, i represents a current, Vb is a voltage value at both ends, Vocv is an open-circuit voltage value, and R is an internal resistance (electric resistance).

  Then, the internal thermal resistance Rin of the secondary battery unit 50 can be obtained from Equation 4 and the heat capacity Cin can be obtained from Equation 5. In this way, the internal temperature Tina can be estimated by applying the thermal circuit model. In Equation 5, τ is a thermal time constant of the secondary battery unit 50.

  Note that the first internal temperature estimation unit 17 in the present embodiment considers that the heat quantity Qout radiated in the thermal circuit of FIG. 3 is a heat flow that flows in both the thermal resistance Rin and the thermal resistance Ra, and the internal temperature Tina. Is estimated and calculated. Specifically, by applying Ohm's law in the thermal circuit to the relationship between the heat flow Qout, the thermal resistance Rin, the thermal resistance Ra, the internal temperature Tina, the surface temperature Ts, and the ambient temperature Ta as in the following formulas 6 and 7. Expression 8 derived from Expression 6 and Expression 7 so as to eliminate the heat flow Qout is obtained. The first internal temperature estimation unit 17 estimates and calculates the internal temperature Tina by applying the temperature Ts and the temperature Ta acquired by the surface temperature acquisition unit 15 and the ambient temperature acquisition unit 16 to Equation 8, respectively.

  Note that the value of the internal thermal resistance Rin of the secondary battery unit 50 in Expression 8 is obtained in advance by measurement. The value of the thermal resistance Ra of the ambient air is a value that varies depending on the cooling conditions of the ambient air. When an air cooling fan is used for the cooling mechanism 56, the thermal resistance value Ra is obtained from the air thermal resistance Ra (0) and the wind speed when there is no wind. The air heat resistance value Ra (0) at the time of no wind is a value that decreases as the surface area of the secondary battery unit 50 increases. The wind speed varies depending on the space in the casing of the secondary battery unit 50 and also varies depending on the voltage applied by the air cooling fan, and therefore varies depending on the packaged secondary battery unit 50. Therefore, the relationship value between the applied voltage to the air cooling fan and the thermal resistance value Ra is measured in advance for the type of package, and the measurement data corresponding to the secondary battery unit 50 to be used or the measurement data is approximated. The specified function information is stored in the storage unit 11. FIG. 4 is a graph showing an example of the relationship between the applied voltage and the air thermal resistance value. The horizontal axis in FIG. 4 indicates the applied voltage in volts, and the vertical axis indicates the thermal resistance value Ra of the ambient air corresponding to the applied voltage in units of [K / W]. The thermal resistance values Ra for different applied voltages on the graph of FIG. 4 are tabulated and stored in the storage unit 11, or information on approximate functions having the applied voltage as a variable is stored in the storage unit 11. The thermal resistance value Ra of ambient air at an arbitrary applied voltage can be obtained and used.

  Secondly, a method for estimating the internal temperature Tinb by the second internal temperature estimation unit 20 will be described. As described above, the second internal temperature estimation unit 20 estimates the internal temperature Tinb of the cell 51 using the internal resistance value R of the secondary battery unit 50.

  FIG. 5 is an explanatory diagram illustrating an example of an equivalent circuit of the secondary battery unit 50. As shown in FIG. 5, the secondary battery unit 50 has an impedance of the secondary battery unit 50 in a circuit in which an electric double layer capacitance C is connected in parallel to a series circuit of an interface charge transfer resistance Rc and a diffusion impedance Zw. The liquid bulk resistance Rs can be equivalently expressed by a circuit connected in series. The resistance Rs of the electrolyte bulk includes an electric resistance of lithium ions in the electrolyte, an electronic resistance at the positive electrode and the negative electrode, and the like. The interface charge transfer resistance Rc includes a charge transfer resistance and a film resistance on the surface of the active material. The diffusion impedance Zw is an impedance resulting from the diffusion process of lithium ions into the active material particles.

  FIG. 6 is a schematic diagram illustrating impedance characteristics of the secondary battery unit 50. The horizontal axis of FIG. 6 shows the real component Zr of the impedance Z, the vertical axis shows the imaginary component Zi of the impedance Z, and represents the impedance spectrum (Cole-Cole plot or Nike plot). When the angular frequency (frequency f) decreases from infinity to 0 (zero), the impedance of the secondary battery unit 50 has an extreme value in a certain frequency range f1 (referred to as a boundary frequency range) in FIG. And then increase. This increase is known to be contributed by the diffusion impedance Zw. That is, in the boundary frequency region, the influence of the diffusion impedance Zw can be ignored. Here, the internal resistance of the secondary battery unit 50 is mainly composed of an electrolyte bulk resistance Rs and an interface charge transfer resistance Rc. Therefore, the impedance Z in the boundary frequency region is estimated as the internal resistance value R. The impedance Z is measured by the AC impedance method. The time corresponding to the boundary frequency region here is the standby time T after the charge / discharge switching (frequency change) specified by the standby time specifying unit 18.

  FIG. 7 is an explanatory diagram showing an example of the content of the standby time T corresponding to the boundary frequency region. As the charging rate decreases, the impedance of the secondary battery unit 50 increases (shifts to the right in FIG. 6) and the boundary frequency region decreases, that is, the standby time T increases as shown in FIG. The standby time T also depends on the temperature of the secondary battery. That is, the correspondence as shown in FIG. 7 exists for each temperature. Therefore, since the specific numerical values of these standby times T are different for each secondary battery unit 50, the storage unit 11 stores the standby time T for each charging rate range and temperature range according to the secondary battery unit 50 to be monitored. Remember. The standby time specifying unit 18 may specify the standby time T by referring to the charging rate and the internal temperature obtained immediately before. Note that the present invention is not limited to storing specific numerical values as shown in FIG. For example, the standby time T0 when the charging rate is 50% and the temperature is 25 ° C., and the charging rate coefficient K0 and the temperature coefficient K1 corresponding to the transition of the standby time T with respect to the charging rate are stored for each secondary battery unit 50. Keep it. Then, the standby time specifying unit 18 may specify the standby time T (= K0 × SOC × T0 + K1 × Tin × T0) by an operation such as multiplying T0 by a coefficient K0 and multiplying by a coefficient K1 for temperature.

  In this way, the internal resistance calculation unit 19 can calculate the internal resistance value R by applying the current value Ic and the voltage value Vb after the standby time T according to the charging rate and the temperature to Equation 9.

  Note that the details disclosed in Japanese Patent Application No. 2016-001983 are used for the detailed method and the basis for calculating the internal resistance value R.

  FIG. 8 is a graph showing the correspondence between the internal resistance value R and the internal temperature. The horizontal axis in FIG. 8 indicates the battery temperature in degrees Celsius, and the vertical axis in FIG. 8 indicates the level of the internal resistance value R. Since the specific numerical value of the internal resistance value R varies depending on the specifications of the cell 51, the illustration is omitted. The correspondence shown in FIG. 8 is obtained from the internal resistance value R measured when the cell 51 of the secondary battery unit 50 is stored in a thermostat and the thermostat is set to a different temperature. As described above, since the internal resistance value R has different impedance characteristics depending on the charging rate, the internal resistance value R is measured not only at different temperatures but also at each charging rate. The graph shown in FIG. 8 shows the correspondence between the internal resistance value R and the battery temperature when the charging rate is 50% to 60%, for example.

  The storage unit 11 stores in advance a correspondence relationship in which the internal resistance value R and the battery temperature as shown in FIG. 8 are tabulated for each range in which the charging rate has a predetermined width (for example, 10%). ing. Specifically, the battery temperature corresponding to different internal resistance values R (for example, several milliohm units) at 10% to 20%, and the battery corresponding to different internal resistance values R at 20% to 30%, respectively. The temperature is stored as the battery temperature corresponding to different internal resistance values R at 30% to 40%,. The correspondence relationship between the internal resistance value R and the battery temperature is not only tabulated, but also by storing in the storage unit 11 information on approximate functions having the internal resistance value R as a variable for each charging rate. The corresponding internal temperature may be referred to from an arbitrary internal resistance value R.

  The second internal temperature estimation unit 20 refers to the corresponding relationship as shown in FIG. 8 of the corresponding charging rate range from the storage unit 11 using the most recently calculated charging rate, and calculates the calculated internal resistance value R. Read the battery temperature corresponding to. The second internal temperature estimation unit 20 estimates the read battery temperature as the internal temperature Tinb.

  FIG. 9 is a graph showing the transition of the internal temperature Tinb estimated by the second internal temperature estimation unit 20. 9A shows the time change of the internal resistance value R calculated by the internal resistance calculation unit 19 for the secondary battery unit 50, and FIG. 9B shows the internal resistance value calculated for the internal resistance value R shown in FIG. 9A. The time lapse of each of the temperature Tinb and the measured surface temperature Ts is shown. In both FIGS. 9A and 9B, the horizontal axis indicates the passage of time from the start of current flow to the cell 51. The vertical axis in FIG. 9A indicates the internal resistance value R in Ω, and the vertical axis in FIG. 9B indicates the temperature of the cell 51 in Celsius. As shown in FIG. 9B, the difference between the surface temperature Ts and the estimated internal temperature Tinb increases as the cell 51 becomes higher in temperature. Note that either or both of the surface temperature Ts and the internal temperature Tinb thereafter converge to a predetermined temperature. Therefore, it is difficult to correctly estimate the true internal temperature by a method of multiplying the surface temperature Ts by a predetermined coefficient or adding a predetermined constant and estimating this as the temperature inside the battery.

  The first internal temperature estimator 17 and the second internal temperature estimator 20 do not simply multiply the surface temperature Ts by a predetermined coefficient, but use different techniques based on a thermal circuit and an equivalent electric circuit, respectively. The internal temperature can be estimated well. In the battery monitoring apparatus 100 in the present embodiment, the temperature abnormality determination unit 21 further compares both or one of them with a predetermined threshold using the internal temperatures Tina and Tinb estimated by different methods as described above. Based on the calculation, it is determined whether or not the temperature inside the battery is abnormal (high temperature).

  The processing procedure by each component of the battery monitoring apparatus 100 is summarized as follows. FIG. 10 is a flowchart illustrating an example of a processing procedure performed by the battery monitoring apparatus 100. The control unit 10 repeatedly executes a processing procedure shown in the following flowchart at a predetermined cycle.

  The voltage acquisition unit 13 acquires the voltage value V, and the current acquisition unit 14 acquires the current value I (step S1).

  Next, the surface temperature acquisition unit 15 acquires the surface temperature Ts, and the ambient temperature acquisition unit 16 acquires the ambient temperature Ta (step S2). The acquired surface temperature Ts and ambient temperature Ta are stored in the internal memory by the control unit 10. Next, the control unit 10 acquires a cooling condition in the cooling mechanism 56 (in this embodiment, an applied voltage to the air cooling fan) (step S3). The internal temperature calculation unit 17 calculates the thermal resistance value Ra of the ambient air corresponding to the applied voltage acquired in step S3 with reference to the storage unit 11 (step S4). The internal temperature calculation unit 17 further applies the acquired temperatures Ts and Ta, the calculated thermal resistance value Ra, and the internal thermal resistance value Rin specific to the secondary battery unit 50 stored in the storage unit 11 to Equation 8. The internal temperature Tina is calculated (step S5).

  Next, the internal resistance calculation unit 19 determines whether or not charging / discharging has been switched (step S6). When it is determined in step S6 that switching has occurred (S6: YES), the internal resistance calculation unit 19 uses the voltage value V and current value I acquired in step S1 as the voltage value Vb and current value Ib at the time of switching, respectively. It memorize | stores in the internal memory of the control part 10 (step S7). Then, the standby time specifying unit 18 refers to the most recently calculated charge rate SOC and internal temperature (a value based on Tina or Tinb) (step S8), specifies the standby time T corresponding to the charge rate and the internal temperature, Wait for that time (step S9).

  Then, after the standby time T has elapsed, the internal resistance calculation unit 19 acquires the voltage value V and the current value I for calculating the internal resistance value R again by the voltage acquisition unit 13 and the current acquisition unit 14, respectively. The voltage value Vc and the current value Ic after T are stored in the internal memory of the control unit 10 (step S10). The internal resistance calculation unit 19 uses the voltage value Vb and current value Ib at the time of switching stored in step S7 and the voltage value Vc and current value Ic after the standby time T stored in step S10. A value R is calculated (step S11).

  Next, the second internal temperature estimation unit 20 refers to the correspondence between the internal resistance value R and the internal temperature of the battery at the charging rate referred in step S8 from the storage unit 11 (step S12), and calculates the internal calculated in step S11. The temperature corresponding to the resistance value R is set as the internal temperature Tinb (step S13).

  Then, the state of charge (SOC) calculation unit 23 calculates the charge rate SOC using the open-circuit voltage OCV calculated by the open-circuit voltage calculation unit 22 based on the internal resistance value R calculated in step S11. The (SOH) calculation unit 24 calculates and stores the health state SOH from the internal resistance value R (step S14).

  And the temperature abnormality determination part 21 performs a temperature abnormality determination process using the internal temperature Tina and the internal temperature Tinb estimated in step S5 and step S13 (step S15), and complete | finishes one process.

  When it is determined in step S6 that there has been no switching (S6: NO), the subsequent step of calculating the internal resistance value R (S7 to S11) and the step of using the calculated internal resistance value R (S12 to 14). Without performing, the control unit 10 advances the process to step S15. In this case, in step S15, determination is made using only the internal temperature Tina calculated in step S5 or the recently estimated internal temperature Tinb. If it is determined in step S6 that there is no switching (S6: NO), the temperature abnormality determination process in step S15 may be omitted.

  Next, details of the temperature abnormality determination process in step S15 in the flowchart of FIG. 10 will be described. Various methods can be considered as the determination method by the temperature abnormality determination unit 21. In this embodiment, the internal temperature Tina estimated by the first internal temperature estimation unit 17 and the second internal temperature estimation unit 20 are estimated. The determination is made using values estimated by two different methods with the internal temperature Tinb.

FIG. 11 is a flowchart illustrating an example of a processing procedure of temperature abnormality determination processing. The temperature abnormality determination unit 21 determines whether or not the condition (Equation 10) that the difference between the internal temperatures Tina and Tinb is equal to or less than a predetermined threshold th1 is satisfied (step S501). When it is determined that Expression 10 is satisfied (S501: YES), the temperature abnormality determination unit 21 determines whether or not the condition that the internal temperatures Tina and Tinb are both higher than the surface temperature (Expression 11) is satisfied (Expression 11). Step S502). The determinations in steps S501 and S502 are processes for confirming the certainty of the estimated internal temperature values Tina and Tinb.
| Tina-Tinb | ≦ th1 (10)
Min (Tina, Tinb)> Ts (11)

  The threshold value th1 in Expression 10 is a value stored in advance in the storage unit 11 such as 3 ° C., for example. Specifically, as for the threshold th1, it is conceivable that the difference between the surface temperature Ts and one of the internal temperature Tina and the internal temperature Tinb is measured in advance as shown in FIG. 9B, and the maximum value of the difference is used. The estimated value of the internal temperature obtained by the different methods described above has been empirically found that the temperature range within the range of use does not deviate as much as the difference from the surface temperature. It is a thing. Therefore, the value of the threshold th1 is not limited to this. In addition, the threshold th1 may be set based on a chemical or physical basis.

When the temperature abnormality determination unit 21 determines that the internal temperature Tina and the internal temperature Tinb satisfy Expressions 10 and 11 (S501: YES and S502: YES), the larger value is equal to or greater than the threshold th2. Whether or not the condition (formula 12) is satisfied is determined (step S503). In step S503, it is not limited to the comparison with the threshold value th2, and it is only necessary to determine whether or not the cell 51 is out of the use range indicated in the specification or the like in order to avoid the shortening of the service life.
Max (Tina, Tinb) ≧ th2 (12)

  The threshold th2 related to the temperature abnormality determination is a value corresponding to the upper limit (eg, 60 ° C.) of the usage range of the battery unit 50 (cell 51). The temperature abnormality determination unit 21 compares the large value of the internal temperature Tina and the internal temperature Tinb with the threshold value th2 for abnormality determination, so that the true internal temperature exceeds the use range of the battery as determined by safety. In spite of this, it is avoided to determine that the temperature is not abnormal.

  When it is determined in step S503 that the threshold is greater than or equal to the threshold th2 (S503: YES), the temperature abnormality determination unit 21 determines that the temperature inside the battery is abnormal (step S504), and ends the process.

  When it is determined in any one of step S501 and step S502 that the condition is not satisfied (S501: NO or S502: NO), the temperature abnormality determination unit 21 uses the surface temperature Ts as a reference and the surface temperature Ts is within the use range. It is determined whether it is outside (for example, threshold value th3 or more) (step S505). In step S505, the temperature abnormality determination unit 21 determines that the internal temperature is higher than the surface temperature Ts, so that the surface temperature Ts is multiplied by a predetermined coefficient or a predetermined constant is added. It may be determined whether or not there is. If it is determined in step S505 that it is outside the use range (S505: YES), the temperature abnormality determination unit 21 advances the process to step S504.

  When it is determined in step S503 that it is less than the threshold th2 (S503: NO), and when it is determined in step S505 that it is within the use range (S505: NO), the temperature abnormality determination unit 21 Since the temperature is not abnormal, the process is terminated.

  In the processing procedure shown in the flowchart of FIG. 11, step S505 is omitted, and it is only determined that the temperature abnormality determination unit 21 is abnormal when it is determined that all the conditions are satisfied in the determinations of steps S501 to S503. Also good.

  In this way, based on the certainty of the values that can be determined from the two internal temperatures Tina and Tinb estimated by different methods, for example, an error caused by the internal temperatures Tina and Tinb that are erroneously estimated to be significantly higher can be obtained. It is possible to avoid the determination. For example, when the determination is made only with the internal temperature Tina estimated by the first internal temperature estimation unit 17, the measurement error of the voltage applied to the cooling mechanism 56 used to derive this influences the value of the internal temperature Tina. When the difference from the internal temperature Tinb is small, it can be estimated that the measurement error is small and the estimated value is likely. Further, when the determination is made only with the internal temperature Tinb estimated by the second internal temperature estimation unit 20, for example, when the measurement error of the voltage value V and the current value I affects depending on the temperature range, the difference from the internal temperature Tina is small. It is possible to estimate that the measurement error is small and the estimated value is likely. In this way, the pros and cons of the estimated temperature by different methods can be compensated for each other, and abnormality determination accuracy can be improved.

(Modification 1)
In the processing procedure shown in the flowchart of FIG. 11, the difference between the internal temperature Tina and the accuracy of estimation of the Tinb is compared with the threshold th1 in Expression 10, and further, the presence or absence of a deviation from the surface temperature Ts is determined in Expression 11. . In the first modification, the difference is compared with two thresholds th4 and th5. FIG. 12 is a flowchart illustrating another example of the processing procedure of the temperature abnormality determination process.

The temperature abnormality determination unit 21 determines whether or not a condition (Equation 13) that the difference between the internal temperatures Tina and Tinb is equal to or less than a predetermined threshold th4 is satisfied (step S511).
| Tina-Tinb | ≦ th4 (13)

If it is determined in step S511 that Expression 13 is satisfied (S511: YES), it is determined whether or not a condition (Expression 14) that the difference is equal to or smaller than a predetermined threshold th5 that is smaller than the threshold th4 is satisfied (Step S511). S512). The threshold th5 may be a value equal to or smaller than the threshold th1 in Expression 10.
| Tina−Tinb | ≦ th5 <th4 (14)

  If it is determined in step S512 that the expression 14 is satisfied (S512: YES), the temperature abnormality determination unit 21 satisfies the condition that the internal temperatures Tina and Tinb are both higher than the surface temperature Ts (expression 11). Is determined (step S513).

  When it is determined in Step S513 that Expression 11 is satisfied (S513: YES), the temperature abnormality determination unit 21 determines that the larger one of the internal temperatures Tina and Tinb is equal to or greater than the threshold th2 (Expression 12). ) Is satisfied (step S514). In step S514, it is not limited to the comparison with the threshold value th2, and it is only necessary to determine whether or not the cell 51 is out of the use range indicated in the specification or the like in order to avoid shortening the service life.

  If it is determined in step S514 that the threshold is greater than or equal to the threshold th2 (S514: YES), the temperature abnormality determination unit 21 determines that the temperature inside the battery is abnormal (step S515), and ends the process.

  If it is determined in step S514 that it is not equal to or greater than the threshold th2 (S514: NO), the temperature abnormality determination unit 21 ends the process as it is.

  If it is determined in step S512 that Expression 14 is not satisfied (S512: NO), the temperature abnormality determination unit 21 does not have a sufficiently small difference between the internal temperatures Tina and Tinb, but must trust one of them. Treat as kimono. Therefore, the temperature abnormality determination unit 21 determines whether or not both the internal temperatures Tina and Tinb are lower than the surface temperature Ts (step S516). When it is determined that either one is equal to or higher than the surface temperature Ts (S516: NO), the temperature abnormality determination unit 21 determines whether the minimum value of the internal temperatures Tina and Tinb is higher than the surface temperature Ts. (Step S517). When it is determined in step S517 that the minimum value is greater than the surface temperature Ts (S517: YES), the temperature abnormality determination unit 21 determines whether the average value of the two internal temperatures Tina and Tinb is equal to or greater than the threshold th2. Judgment is made (step S518). In the case where it is determined in step S517 that the temperature is higher than the surface temperature Ts, that is, the internal temperatures Tina and Tinb are both values higher than the surface temperature Ts, but the difference is not small enough to be reliable. It is. In this case, if the maximum value is compared with the threshold th2 as in step S514, there is a risk of erroneous determination. By comparing the average value with the threshold th2 in step S518, the risk of erroneous determination is reduced. If it is determined in step S518 that the threshold is greater than or equal to the threshold th2 (S518: YES), the temperature abnormality determination unit 21 determines that the temperature is abnormal (S515), and ends the process.

  When it is determined in step S518 that it is less than the threshold th2 (S518: NO), the temperature abnormality determination unit 21 ends the process as it is.

  When it is determined in step S517 that the minimum value is equal to or lower than the surface temperature Ts (S517: NO), the temperature abnormality determination unit 21 proceeds to step S514, and determines whether the larger value is equal to or greater than the threshold th2. Is determined (S514).

  If it is determined in step S511 that Expression 13 is not satisfied (S511: NO), it is unknown which of the estimated values is reliable, so the surface temperature Ts is used on the basis of the measured surface temperature Ts. It is determined whether it is out of range (for example, threshold value th3 or more) (step S519). If it is determined in step S519 that the temperature is outside the use range (S519: YES), the temperature abnormality determination unit 21 proceeds to step S515 to determine that the temperature is abnormal (S515), and ends the process. When it is determined in step S519 that it is within the use range (S519: NO), the temperature abnormality determination unit 21 ends the process as it is.

  When it is determined in step S513 that one of the internal temperatures Tina and Tinb is equal to or lower than the surface temperature Ts (S513: NO), and when it is determined in step S516 that both are equal to or lower than the surface temperature Ts ( (S516: YES), the temperature abnormality determination unit 21 advances the process to step S519.

  As shown in the first modification, two threshold values are provided for the two internal temperatures Tina and Tinb estimated by different methods, and the magnitude of the threshold is determined, thereby making it possible to eliminate the erroneous estimated value and improve the accuracy. It becomes possible to determine a temperature abnormality well.

(Modification 2)
In the second modification, a factor such as temperature or time is further taken into consideration to determine whether the temperature abnormality is determined based on the internal temperature Tina or Tinb. FIG. 13 is a flowchart illustrating another example of the processing procedure of the temperature abnormality determination process. Of the processing procedures shown in the flowchart of FIG. 13, processing that is the same as the processing procedure shown in the flowchart of FIG. 11 is given the same step number, and detailed description thereof is omitted.

  The temperature abnormality determination unit 21 first determines whether or not the surface temperature Ts is equal to or lower than a threshold th6 corresponding to a so-called normal temperature (step S521). When it is determined in step S521 that the surface temperature Ts is equal to or lower than the threshold th6 (S521: YES), the temperature abnormality determination unit 21 determines whether or not the elapsed time since the most recent charge / discharge switching is within a predetermined time. Is determined (step S522). The predetermined time referred to here may be, for example, a fixed period in view of the temperature abnormality determination cycle, or may be determined based on a standby time T that varies depending on the charge rate SOC.

  When it is determined in step S522 that the time is within the predetermined time (S522: YES), the temperature abnormality determination unit 21 executes the processes of steps S501 to S505.

  When it is determined that either one of steps S521 and S522 is NO (S521: NO or S522: NO), the temperature abnormality determination unit 21 uses only the internal temperature Tina estimated and calculated from the thermal resistance value. It is determined whether or not the threshold is greater than or equal to the threshold th2 (step S523). If it is determined in step S523 that the temperature is greater than or equal to the threshold th2 (S523: YES), the temperature abnormality determination unit 21 determines that the temperature is abnormal (S504), and if it is determined that the temperature is less than the threshold th2 (S523). : NO), the temperature abnormality determination unit 21 ends the process as it is.

  As shown in FIG. 8, the internal resistance value R changes less with respect to the temperature change in the high temperature range of 25 ° C. or higher, so that the measurement error of the voltage value V and the current value I used for estimation is large. Affects estimation. In the second modification, when the temperature is equal to or higher than normal temperature (S521: NO), the influence of this measurement error can be suppressed by determining the temperature abnormality without using the estimated value of the internal resistance value R. In addition, when the secondary battery unit 50 is used for a battery, the charging / discharging switching timing arrives at a sufficient frequency. In other applications, the charging / discharging switching does not occur for a period longer than the temperature abnormality determination cycle. There is a case. In such a case, since the internal resistance value R cannot be calculated in accordance with the temperature change timing, the determination accuracy is maintained by executing the temperature abnormality determination using the internal temperature Tinb estimated based on the thermal resistance. be able to.

  In the present embodiment described above, the processing procedure shown in the flowchart of FIG. 13 can be added to the first modification. Either one of the internal temperatures Tina and Tinb is appropriately selected on the basis of only one of the temperature and the time shown in the modified example 2, and the selected estimated internal temperature is compared with the threshold th2 to determine a temperature abnormality. May be.

  In this way, the two internal temperatures Tina and Tinb estimated by different methods are appropriately used according to the certainty estimated from the values themselves or the situation of the other secondary battery unit 50, etc. Since the determination is made, the determination accuracy can be increased and maintained.

  In the above-described embodiment, the internal temperature calculation target is the secondary battery unit 50 mounted on the vehicle. However, it goes without saying that a battery that is a target of temperature abnormality determination by the temperature abnormality determination device of the present disclosure is not limited to a secondary battery mounted on a vehicle.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

100 Battery monitoring device (temperature abnormality determination device)
DESCRIPTION OF SYMBOLS 10 Control part 11 Memory | storage part 12 Timer 13 Voltage acquisition part 14 Current acquisition part 15 Surface temperature acquisition part 16 Ambient temperature acquisition part 17 1st internal temperature estimation part 18 Standby time specific | specification part 19 Internal resistance calculation part 20 2nd internal temperature estimation part DESCRIPTION OF SYMBOLS 21 Temperature abnormality determination part 22 Open circuit voltage calculation part 23 Charging state calculation part 24 Health condition calculation part 25 Output part 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 54 1st temperature sensor 55 2nd temperature sensor 56 Cooling mechanism

Claims (9)

A temperature abnormality determination device that determines whether or not the temperature of the secondary battery is abnormal,
A first internal temperature of the secondary battery is estimated using a thermal resistance value based on a thermal circuit model of the secondary battery and an ambient air of the secondary battery, and a surface temperature and an ambient temperature of the secondary battery. A first temperature estimating unit that
A second temperature estimating unit for estimating a second internal temperature of the secondary battery based on an internal resistance value of the secondary battery;
A temperature abnormality determination device comprising: a determination unit that determines whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature. The temperature abnormality determination device according to claim 1, wherein the determination unit interrupts determination when a difference between the first internal temperature and the second internal temperature is equal to or greater than a predetermined threshold. The determination unit
Determining whether the difference is less than or equal to a second threshold that is less than the predetermined threshold;
If it is determined that the temperature is equal to or lower than the second threshold, it is determined whether a maximum value of the first internal temperature and the second internal temperature is within a predetermined range;
The temperature abnormality determination device according to claim 1, wherein when it is determined that the temperature is outside the predetermined range, the temperature of the secondary battery is determined to be abnormal. A surface temperature acquisition unit for acquiring the surface temperature of the secondary battery;
The determination unit interrupts determination when at least one of the first internal temperature and the second internal temperature is lower than the surface temperature acquired by the surface temperature acquisition unit. Temperature abnormality determination device. The determination unit
When the difference between the first internal temperature and the second internal temperature is less than a predetermined threshold, and the minimum value of the first internal temperature and the second internal temperature is equal to or higher than the surface temperature, Determining whether the maximum value of the internal temperature of 1 and the second internal temperature is within a predetermined range;
The temperature abnormality determination device according to claim 4, wherein when it is determined that the temperature is outside the predetermined range, the temperature of the secondary battery is determined to be abnormal. A voltage acquisition unit for acquiring a voltage of the secondary battery;
A current acquisition unit for acquiring a current of the secondary battery;
A specifying unit for specifying a standby time based on a boundary frequency region in which a diffusion impedance caused by a diffusion process of predetermined ions in the impedance spectrum of the secondary battery contributes to the impedance of the secondary battery;
The voltage value and the current value acquired by the voltage acquisition unit and the current acquisition unit, respectively, and the voltage value and the current value acquired after the standby time from the timing at the charge / discharge switching timing of the secondary battery. An internal resistance calculation unit for calculating the internal resistance value using
A storage unit that stores in advance the correspondence between the internal resistance value of the secondary battery and the temperature;
The temperature abnormality according to claim 1, wherein the second temperature estimation unit refers to a temperature corresponding to the internal resistance value calculated by the internal resistance calculation unit from the storage unit, and estimates the temperature as a second internal temperature. Judgment device. A charge rate acquisition unit for acquiring a charge rate of the secondary battery;
The storage unit stores in advance the correspondence between the internal resistance value of the secondary battery and the temperature for different charging rates,
The second temperature estimation unit uses the internal resistance value calculated by the internal resistance calculation unit, and refers to the temperature corresponding to the internal resistance value at the charging rate acquired by the charging rate acquisition unit from the storage unit. The temperature abnormality determination device described in 1. A temperature abnormality determination method for determining whether or not the temperature of a secondary battery is abnormal,
A first internal temperature of the secondary battery is estimated using a thermal resistance value based on a thermal circuit model of the secondary battery and the ambient air of the secondary battery, a surface temperature of the secondary battery, and an ambient temperature. And
Estimating a second internal temperature of the secondary battery based on an internal resistance value of the secondary battery;
A temperature abnormality determination method for determining whether or not the temperature of the secondary battery is abnormal using the first internal temperature and the second internal temperature. A computer program for causing a computer to determine whether or not the temperature of the secondary battery is abnormal,
A first internal temperature of the secondary battery is estimated using a thermal resistance value based on a thermal circuit model of the secondary battery and the ambient air of the secondary battery, a surface temperature of the secondary battery, and an ambient temperature. And
Estimating a second internal temperature of the secondary battery based on an internal resistance value of the secondary battery;
The computer program which performs the process which determines whether the temperature of the said secondary battery is abnormal using the said 1st internal temperature and 2nd internal temperature.

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