Battery control device and battery system

Abstract

This battery control device of a battery system includes: a first calculation unit for calculating a first charging state of a battery by a first method on the basis of the current value, voltage value, and internal resistance value of the battery; a second calculation unit for calculating a second charging state of the battery by a second method different from the first method; and a correction unit for correcting the internal resistance value of the battery. When a difference of a predetermined value or more is detected between the first charging state and the second charging state, the correction unit corrects the internal resistance value of the battery by a resistance correction amount dependent on the difference and the current value.

Description

[Technical field]

[0001] The present invention relates to a battery control device and a battery system. [Background technology]

[0002] An electric vehicle system installed in an electric vehicle such as an electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), or a hybrid electric vehicle (HEV) has a battery as a power supply source and a battery control device. In order to maximize the performance of the battery, the battery control device detects the battery's voltage, temperature, and current, and calculates the battery's state of charge (SOC), state of health (SOH), and the amount of power that can be input and output from the battery based on these.

[0003] As a battery deteriorates, its internal resistance increases. For this reason, the internal resistance of the battery is calculated in real time and used to properly calculate the battery's available input and output power. The ratio of the initial internal resistance to the internal resistance after deterioration is calculated as the SOH and used as a guide for battery replacement.

[0004] Here, there are two methods for calculating the internal resistance of a battery: a method for calculating based on the internal resistance of the battery calculated from the ratio of the amount of change in battery voltage to the amount of change in battery current, and a method for calculating based on the internal resistance calculated using an equivalent circuit model of the battery.

[0005] For example, Patent Document 1 discloses a technology in which the SOC difference between an SOC calculated based on internal resistance using an internal resistance calculation method based on the latter equivalent circuit model (hereinafter referred to as SOCv) and an SOC based on current integration (hereinafter referred to as SOCi) is detected as a change in internal resistance due to battery degradation, and the internal resistance used to calculate the SOH is corrected. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5439126 Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned conventional technology, the correction value of the internal resistance, which is determined to require correction due to the occurrence of an SOC difference, is set to a relatively small fixed value, emphasizing the stability of the calculation. Therefore, even when the calculated SOH value recognized by the battery control device and the actual SOH (also called the true SOH value) of the battery to be controlled differ greatly, the internal resistance is corrected with a small fixed value, which causes a problem that the convergence speed of the calculated SOH value to the true SOH value is slow.

[0008] In order to solve the above-mentioned problems, an object of the present invention is to provide a battery control device and a battery system that can increase the convergence speed of the SOH calculation value and estimate the internal resistance value with high accuracy. [Means for solving the problem]

[0009] In order to solve the above problems, in the present invention, a battery control device includes a first calculation unit that calculates a first state of charge of the battery using a first method based on the battery's current value, voltage value, and internal resistance value, a second calculation unit that calculates a second state of charge of the battery using a second method different from the first method, and a correction unit that corrects the internal resistance value of the battery, and when a difference between the first state of charge and the second state of charge of a predetermined value or more is detected, the correction unit corrects the internal resistance value of the battery with a resistance correction amount corresponding to the difference and the current value. Effect of the Invention

[0010] According to the present invention, it is possible to achieve both convergence and accuracy of the calculated value of the internal resistance of the battery, thereby ensuring the reliability of the battery system and enabling the battery to be used efficiently. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a configuration of an electric power system of a hybrid vehicle according to a first embodiment of the present invention. [Diagram 2] 2 is a block diagram showing the configuration of a unit cell control unit that constitutes the battery system of FIG. 1. [Diagram 3] 2 is a block diagram showing the configuration of a battery pack control unit that constitutes the battery system of FIG. 1; [Figure 4] 4A to 4C are diagrams showing a SOC table, an internal resistance table, and a polarization resistance table. [Diagram 5] FIG. 2 is a block diagram showing the configuration of a SOC calculation unit constituting the battery pack control unit in the first embodiment. [Figure 6] An example of characteristics showing the relationship between SOC and OCV of a single cell. [Figure 7] FIG. 4 is a diagram showing an example of an equivalent circuit model of a single cell. [Figure 8] FIG. 4 is a diagram for explaining the voltage behavior of a single cell. [Figure 9] FIG. 4 is a block diagram showing a configuration of an internal resistance calculation execution determination unit in the first embodiment. [Figure 10] FIG. 2 is a block diagram showing a configuration of a SOH calculation unit in the first embodiment. [Figure 11] FIG. 4 is a diagram showing an internal resistance correction amount map in the first embodiment. [Figure 12] 4 is a flowchart showing a SOH calculation process in the first embodiment. [Figure 13] FIG. 13 is a diagram showing a profile of SOH calculation when charge / discharge pulses are input in the conventional technology. [Figure 14] FIG. 4 is a diagram showing a profile of SOH calculation when a charge / discharge pulse is input in the first embodiment. [Figure 15] FIG. 11 is a block diagram showing the configuration of a SOH calculation unit in the second embodiment. [Figure 16] FIG. 11 is a diagram showing an internal resistance correction amount map in the second embodiment. [Figure 17] FIG. 13 is a diagram showing a profile of SOH calculation when charge / discharge pulses are input in a high temperature region in the first embodiment. [Figure 18] FIG. 13 is a diagram showing a calculated SOH profile when charge / discharge pulses are input in a high temperature region in the second embodiment. [Figure 19] FIG. 13 is a diagram showing a resistance correction amount map in a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described with reference to the drawings. The drawings referred to in the description of the present invention are merely illustrative. The present invention is not limited to the following embodiments, and the disclosure of the present invention also includes a form in which a part or all of each embodiment and its modified examples are combined without any contradiction. In the following, only the configurations and processes related to the present invention will be described, and descriptions of other configurations and processes may be omitted. In the following, the same or similar configurations and processes are given the same reference numerals and duplicate descriptions are omitted, and duplicate descriptions of the same or similar configurations and processes as those of the previously described embodiments may be omitted in the later embodiments.

[0013] In the following description, when multiple elements with the same name and a symbol with a subnumber added to the same number are collectively referred to, for example, as "xxx100a" and "xxx100b," they will be represented using only the same number, such as "xxx100." Similarly, when multiple elements with the same name and a symbol with a subscript added to the same symbol are collectively referred to, such as "YYYzzz1" and "YYYzzz2," they will be represented using only the same number, such as "YYY."

[0014] In the embodiment described below, the case where the invention is applied to a power storage device constituting the power source of a hybrid electric vehicle (HEV) will be described as an example. However, the invention is not limited to this, and the configuration of the embodiment described below can also be applied to a power storage device control circuit of a power storage device constituting the power source of passenger cars such as plug-in hybrid electric vehicles (PHEV) and electric vehicles (EV), and industrial vehicles such as hybrid railway cars.

[0015] In the following embodiment, a lithium ion battery is used as the power storage device constituting the power storage unit. Other types of power storage devices such as nickel-metal hydride batteries, lead batteries, electric double layer capacitors, and hybrid capacitors can also be used. EXAMPLES

[0016] A first embodiment of the present invention will be described with reference to FIGS.

[0017] 1 is a block diagram showing the configuration of an electric power system S of a hybrid vehicle according to a first embodiment of the present invention. In the electric power system S of this embodiment, a battery system 100 is connected to an inverter 400 and a motor 410 via relays 300 and 310. A vehicle control unit 200 determines the distribution of driving force and the like based on information such as the SOC of the battery system 100, information from the inverter 400 and the motor 410, and information from an engine (not shown).

[0018] The configuration of the battery system 100 will be described. The battery system 100 includes an assembled battery 110 composed of a plurality of cells 111, a cell management unit 120 that monitors the state of the cells 111, a current detection unit 130 that detects the current flowing through the battery system 100, a voltage detection unit 140 that detects the total voltage of the assembled battery 110, a battery assembly control unit 150 that controls the assembled battery 110, and a memory unit 180 that stores information related to the battery characteristics of the cells 111, the cell group 112, and the assembled battery 110.

[0019] The assembled battery control unit 150 receives the battery voltage and temperature of the battery 111 transmitted from the cell management unit 120, the current value flowing through the battery system 100 transmitted from the current detection unit 130, the total voltage value of the assembled battery 110 transmitted from the voltage detection unit 140, and further a diagnosis result of whether the battery 111 is overcharged or overdischarged, and an abnormality signal output when a communication error occurs in the cell management unit 120, and detects the state of the assembled battery 110 based on the input information. In addition, the results of processing performed by the assembled battery control unit 150 are transmitted to the cell management unit 120 and the vehicle control unit 200.

[0020] The battery pack 110 is configured by electrically connecting in series a plurality of cells 111 (lithium ion batteries) capable of storing and discharging electric energy (charging and discharging DC power). An example will be described in which an output voltage of one cell 111 is 3.0 to 4.2 V (average output voltage: 3.6 V) and the OCV and SOC of the cell 111 have a correlation as shown in Fig. 6, but other voltage specifications may also be used.

[0021] The cells 111 constituting the battery pack 110 are grouped into a predetermined number of units for managing and controlling their states. The grouped cells 111 are electrically connected in series to form a cell group 112. The predetermined number of units may be an equal division, for example, 1 cell, 4 cells, 6 cells, etc., or a composite division, for example, a combination of 4 cells and 6 cells.

[0022] The cell management unit 120 that monitors the state of the cells 111 that constitute the battery pack 110 is composed of a plurality of cell control units 121, and one cell control unit 121 is assigned to each of the cell groups 112 that are grouped as described above. The cell control unit 121 operates by receiving power from the assigned cell group 112, and monitors the battery voltage and temperature of the cells 111 that constitute the cell group 112. In FIG. 1, the cell control units 121a and 121b are provided corresponding to the cell groups 112a and 112b. In this embodiment, for the sake of simplicity, the cell group 112 is configured such that four cells 111 are electrically connected in series, and one cell control unit 121 monitors the four cells 111.

[0023] 2 is a block diagram showing the configuration of the cell control unit 121 constituting the battery system 100 of FIG. 1. The cell control unit 121 includes a voltage detection circuit 122, a control circuit 123, a signal input / output circuit 124, and a temperature detection unit 125. The voltage detection circuit 122 measures the terminal voltage of each cell 111. The temperature detection unit 125 measures the temperature of the cell group 112. The control circuit 123 receives the measurement results from the voltage detection circuit 122 and the temperature detection unit 125, and transmits them to the battery pack control unit 150 via the signal input / output circuit 124. Note that a circuit configuration that is generally implemented in the cell control unit 121 and that equalizes the voltage and SOC variations between the cells 111 that occur due to self-discharge, current consumption variations, etc. is well known, so a description thereof is omitted.

[0024] The temperature detection unit 125 included in the cell control unit 121 in FIG. 2 has a function of measuring the temperature of the cell group 112. The temperature detection unit 125 measures one temperature of the cell group 112 as a whole, and handles the temperature as a representative value of the temperature of the cell 111 constituting the cell group 112. The temperature measured by the temperature detection unit 125 is used for various calculations for detecting the state of the cell 111, the cell group 112, or the assembled battery 110. Since FIG. 2 is based on the representative value of the temperature, one temperature detection unit 125 is provided in the cell control unit 121. It is also possible to provide a temperature detection unit 125 for each cell 111 to measure the temperature for each cell 111 and perform various calculations based on the temperature for each cell 111; however, in this case, the number of temperature detection units 125 increases, and the configuration of the cell control unit 121 becomes more complex.

[0025] 2 shows a simplified temperature detection unit 125. In reality, a temperature sensor is installed on the object to be measured, and the installed temperature sensor outputs temperature information as a voltage, and the measurement result is transmitted to the signal input / output circuit 124 via the control circuit 123, and the signal input / output circuit 124 outputs the measurement result to the outside of the cell control unit 121. A function for realizing this series of steps is implemented in the cell control unit 121 as the temperature detection unit 125, but the voltage detection circuit 122 can also be used to measure the temperature information (voltage).

[0026] Returning to FIG. 1, the battery pack control unit 150 and the cell management unit 120 transmit and receive signals by the signal communication unit 160 via an insulating element 170 such as a photocoupler. The insulating element 170 is provided because the battery pack control unit 150 and the cell management unit 120 use different operating power sources. That is, the cell management unit 120 receives power from the battery pack 110, whereas the battery pack control unit 150 uses a battery for on-board accessories (e.g., a 12V battery) as its power source. The insulating element 170 may be mounted on a circuit board constituting the cell management unit 120, or may be mounted on a circuit board constituting the battery pack control unit 150. Depending on the system configuration, the insulating element 170 may be omitted.

[0027] The signal communication unit 160 between the assembled battery control unit 150 and the cell control units 121a and 121b in this embodiment will be described. The cell control units 121a and 121b are connected in series in descending order of potential of the cell groups 112a and 112b that they monitor. A signal transmitted by the assembled battery control unit 150 is input to the cell control unit 121a by the signal communication unit 160 via an insulating element 170. The output of the cell control unit 121a and the input of the cell control unit 121b are also connected by the signal communication unit 160 to transmit signals.

[0028] In this embodiment, the insulating element 170 is not interposed between the cell control units 121a and 121b, but the insulating element 170 may be interposed therebetween. The output of the cell control unit 121b is input to the assembled battery control unit 150 by the signal communication unit 160 via the insulating element 170. In this manner, the assembled battery control unit 150 and the cell control units 121a and 121b are connected in a loop by the signal communication unit 160. This loop connection may also be called a daisy chain connection.

[0029] The configuration of the battery pack control unit 150 will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the configuration of the battery pack control unit 150 constituting the battery system 100 of Fig. 1. In this embodiment, for simplicity, explanations of the diagnosis results regarding the single cells 111 and the processing contents based on the abnormality signal output when a communication error or the like occurs in the single cell management unit 120 will be omitted, and the configuration related to SOC and SOH calculation will be described.

[0030] The battery pack control unit 150 includes an SOC calculation unit 151, an internal resistance calculation execution determination unit 152, and an SOH calculation unit 153. The SOC calculation unit 151 receives the average voltage of each cell 111 constituting the battery pack 110, the current flowing through the battery pack 110, the temperature of the battery pack 110, and the SOH output by the SOH calculation unit 153, and outputs SOC and SOCv. The calculation process of SOC and SOCv will be described later.

[0031] The internal resistance calculation execution determination unit 152 receives as input the average voltage of each cell 111 constituting the battery pack 110, the current flowing through the battery pack 110, the temperature of the battery pack 110, and the SOC and SOCv output by the SOC calculation unit 151, determines whether or not the SOH calculation can be performed, and outputs the determination result. The SOH calculation unit 153 receives as input the SOC and SOCv output by the SOC calculation unit 151, and the temperature, current, and the determination result output by the internal resistance calculation execution determination unit 152, calculates and outputs the SOH. The calculated SOC and SOH are transmitted to the vehicle control unit 200.

[0032] The memory unit 180 stores information such as internal resistance characteristics, full charge capacity, polarization resistance characteristics, deterioration characteristics, individual difference information, and correspondence between SOC and OCV of the assembled battery 110, the cell 111, and the cell group 112. Note that, in this embodiment, the memory unit 180 is configured to be installed outside the assembled battery control unit 150 or the cell management unit 120, but the memory unit may be provided in the assembled battery control unit 150 or the cell management unit 120.

[0033] 4 is a diagram showing the SOC table 181, the internal resistance table 182, and the polarization resistance table 183. The SOC table 181, the internal resistance table 182, and the polarization resistance table 183 are stored in the storage unit 180.

[0034] As shown in FIG. 4(a), the SOC table 181 is a data table that describes the correspondence between the SOC and the OCV (Open Circuit Voltage) of the cell 111 according to temperature.

[0035] 4(b), the internal resistance table 182 is a data table describing the correspondence between the temperature and SOC of the cell 111 and the initial resistance value RoInit of Ro. The initial resistance value RoInit of Ro is the resistance value of Ro when the cell 111 is new when the cell 111 is represented by an equivalent circuit as shown in FIG.

[0036] 4(c), the polarization resistance table 183 is a data table describing the correspondence between the temperature and SOC of the battery 111 and the initial resistance value RpInit of Rp. The initial resistance value RpInit of Rp is the resistance value of Rp when the battery is new when the battery 111 is represented by an equivalent circuit as shown in FIG.

[0037] Although a data table has been used in the description of this embodiment, the respective correspondences may be expressed by mathematical expressions or the like, and are not limited to the form of the data table shown in the figure.

[0038] The SOC calculation unit 151 constituting the battery pack control unit 150 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a block diagram showing the configuration of the SOC calculation unit 151 constituting the battery pack control unit 150 in the first embodiment. Fig. 6 is a characteristic example showing the relationship between the SOC and OCV of the single battery 111.

[0039] As shown in FIG. 5, the SOC calculation unit 151 includes an SOCi calculation unit 151-1, an SOCv calculation unit 151-2, and a combination calculation unit 151-3.

[0040] The SOCi calculation unit 151-1 receives as input the current and the previous value of the SOC calculation result (the calculation result from one cycle ago) output by the combination calculation unit 151-3, and calculates and outputs an SOC (hereinafter, SOCi) based on the integrated value of the current. The SOCv calculation unit 151-2 calculates an OCV based on the battery voltage, current, and temperature, and calculates an SOC (hereinafter, SOCv) based on the correspondence between OCV and SOC shown in Figures 4(a) and 6. The combination calculation unit 151-3 receives as input SOCi and SOCv, and calculates and outputs a weighted average of SOCi and SOCv.

[0041] Next, the SOCi calculation unit 151-1 will be described. SOCi is calculated as shown in the following formula (1) by adding the amount of change in SOC caused by the current flow to the previous value (the calculation result from one cycle ago) of the result output by the combination calculation unit 151-3.

[0042]

number

[0043] Here, SOC_old is the previous SOC value (the calculation result from one cycle ago) obtained by equation (4) described later, I is the current, Qmax is the full charge capacity of the single battery 111, and ts is the control period (the sampling period for current, voltage, etc.).

[0044] The SOCv calculation unit 151-2 will be described with reference to Fig. 7 and Fig. 8. Fig. 7 shows an equivalent circuit diagram of the cell 111, and Fig. 8 shows the behavior of the voltage when a charging current flows through the cell 111. The cell 111 has a circuit configuration in which a DC power supply simulating the OCV representing the open circuit voltage of the battery, Ro representing the electrical resistance of the electrodes, electrolyte, etc., and a parallel circuit of Rp and C modeling the resistance component (polarization component) associated with the electrochemical reaction of the battery are connected in series.

[0045] As shown in Figure 8, when charging current flows, a voltage rise occurs at the OCV due to Ro, and then a gradual voltage rise (polarization voltage) occurs due to Rp. If the voltage rise due to Ro is Vo and the polarization voltage is Vp, then the OCV can be expressed by the following equation (2) from the equivalent circuit shown in Figure 7.

[0046]

number

[0047] Ro and Rp included in the above formula (2) are the results of multiplying the initial resistance values ​​RoInit and RpInit of the cell 111 by SOH_old, which is the rate of increase (%) of the internal resistance, as shown in the following formula (3). SOH_old in the following formula (3) is the previous value (the calculation result of one cycle before) obtained by formula (6) described later.

[0048]

number

[0049] RoInit and RpInit in the above formula (3) are calculated based on the current SOC and temperature by referring to the internal resistance table 182 and the polarization resistance table 183 stored in advance in the storage unit 180. The SOCv calculation unit 151-2 calculates the OCV from the first to third formulas of the above formula (2), and calculates the SOC corresponding to the OCV as SOCv, as shown in the fourth formula in Fig. 4(a) and Fig. 6.

[0050] The combination calculation unit 151-3 will be described below. The combination calculation unit 151-3 receives the SOCi calculated by the SOCi calculation unit 151-1, the SOCv calculated by the SOCv calculation unit 151-2, the current, and the temperature as inputs, and calculates the SOC based on the following formula (4).

[0051]

number

[0052] Here, w is a weighting coefficient, which is calculated, for example, from the following formula (5).

[0053]

number

[0054] According to equations (4) and (5), when the current is large, w becomes small and the degree of bias toward SOCi becomes high, and conversely, when the current is small, w becomes large and the degree of bias toward SOCv becomes high. In this embodiment, in order to avoid the influence of SOCv error associated with resistance error when current is passed, a weighting coefficient as in equation (5) is set, but the present invention is not limited to this.

[0055] Next, the internal resistance calculation execution determination unit 152 will be described with reference to Fig. 9. Fig. 9 is a block diagram showing the configuration of the internal resistance calculation execution determination unit 152 in the first embodiment.

[0056] First, the configuration of the internal resistance calculation execution determination unit 152 will be described with reference to Fig. 9. The internal resistance calculation execution determination unit 152 includes an internal resistance error detection unit 152-1 that receives the SOC and SOCv from the SOC calculation unit 151 and determines whether or not the resistance value used in the calculation of SOCv has an error of a predetermined value or more, a calculation execution determination unit 152-2 that determines whether or not the SOC, current, and voltage are within predetermined ranges, and a correction feasibility determination unit 152-3 that determines whether or not a correction process for the internal resistance can be executed based on the respective determination results of the internal resistance error detection unit 152-1 and the calculation execution determination unit 152-2.

[0057] If the absolute value of the difference between the SOC output by the SOC calculation unit 151 and SOCv (the error of SOCv) is greater than a predetermined value, the internal resistance error detection unit 152-1 determines that there is a mismatch between the internal resistance value used in the calculation of SOCv and the internal resistance value of the battery to be controlled, and outputs the determination result.

[0058] Next, the calculation execution determination unit 152-2 receives the SOC, current, and temperature as inputs and determines whether or not to execute a correction calculation for the internal resistance value. Specifically, it checks whether the SOC, current, and temperature calculated by the SOC calculation unit 151 are within a predetermined range, and when the condition that all are within the predetermined range is satisfied, it enables the calculation and outputs the determination result. The predetermined ranges of the SOC, current, and temperature are determined taking into consideration the effects of the battery characteristics, SOC error, and current and temperature sensor errors, and are stored in the storage unit 180.

[0059] The correction possibility determination unit 152-3 determines whether or not to execute a correction calculation for the internal resistance based on the determination results of the internal resistance error detection unit 152-1 and the calculation execution determination unit 152-2. In this embodiment, when a resistance error is detected and the SOC, temperature, and current are within a predetermined range, the correction calculation for the internal resistance is executed, and in other cases, the correction calculation for the internal resistance is not executed.

[0060] Next, the configuration of the SOH calculation unit 153 will be described with reference to Fig. 10. Fig. 10 is a block diagram showing the configuration of the SOH calculation unit in the first embodiment. The SOH calculation unit 153 includes an internal resistance correction amount calculation unit 153-1, an internal resistance correction unit 153-2, and an SOH calculation unit 153-3.

[0061] The internal resistance correction amount calculation unit 153-1 receives the SOC, SOCv, and current as inputs, calculates the internal resistance correction amount based on the resistance correction amount map shown in Fig. 11, and outputs the calculated amount to the internal resistance correction unit 153-2. The internal resistance correction unit 153-2 receives the judgment result of the internal resistance calculation execution judgment unit 152, the SOC, and the temperature as inputs, and when it is judged that the calculation of the internal resistance correction amount can be executed, corrects the initial resistance value RoInit of the internal resistance Ro corresponding to the SOC and temperature in the internal resistance table 182 stored in the memory unit 180, and outputs the corrected internal resistance value Ro to the SOH calculation unit 153-3.

[0062] The SOH calculation unit 153-3 calculates the SOH using the following formula (6) based on the corrected internal resistance value Ro and the initial resistance value RoInit corresponding to the SOC and temperature. The corrected internal resistance value Ro may be used for various battery controls in addition to the SOH calculation based on the following formula (6). Note that in the example shown in the following formula (6), the SOH is the ratio of Ro to RoInit, but it may also be the ratio of Rp to RpInit corrected in the same manner as Ro.

[0063]

number

[0064] When it is determined that the internal resistance calculation cannot be performed based on the determination result of either the internal resistance error detection unit 152-1 or the calculation execution determination unit 152-2, the internal resistance correction unit 153-2 does not correct the internal resistance value, that is, the internal resistance value calculated in the most recent calculation cycle in which it was determined that the internal resistance calculation was executable is output. For example, when calculation processing is performed in a predetermined calculation cycle, if it was determined that the internal resistance calculation was executable one cycle before the calculation cycle in which it was determined that the execution was not possible, the internal resistance value calculated in the calculation cycle one cycle before that is output.

[0065] Next, the processing contents of the internal resistance correction amount calculation unit 153-1 will be described with reference to Fig. 11. Fig. 11 shows an example of a map of the resistance correction amount according to the current value and the SOC difference (SOCv-SOC). In this embodiment, it is assumed that the SOC difference is detected as an error associated with a deviation in the internal resistance, and the internal resistance is corrected. Therefore, the larger the SOC difference, the larger the deviation in the internal resistance. In other words, the larger the SOC difference, the larger the value of the internal resistance to be corrected is set, that is, a large resistance correction amount is set.

[0066] Next, consider the current dependency of the correction amount. When the SOC difference is the same, that is, when the SOCv error is the same, according to the above formula (2), the errors of Vo and Vp caused by the deviation of the internal resistance are also the same. Since the errors of Vo and Vp are determined by the product of the current and the internal resistance, when the errors of Vo and Vp are constant, the smaller the current, the larger the deviation of the internal resistance, and the larger the current, the smaller the deviation of the internal resistance. If the correction amount of the internal resistance is specified to reflect this, the smaller the absolute value of the current value, the larger the resistance correction amount will be, and the larger the absolute value of the current value, the smaller the resistance correction amount will be.

[0067] In summary, the resistance correction amount map should be constructed so that the internal resistance correction amount is set to a larger value the greater the difference between the SOC calculated value (SOCv) using internal resistance and the SOC calculated using a method other than SOCv, and the smaller the absolute value of the current value.

[0068] The internal resistance correction amount according to the SOC difference and the current shown in FIG. 11 may be determined in advance as a map or a table and stored in the storage unit 180, or the relationship may be described as a mathematical formula and implemented as the formula.

[0069] Next, the SOH calculation process in the first embodiment will be described with reference to the flowchart in Fig. 12. Fig. 12 is a flowchart showing the SOH calculation process in the first embodiment. The SOH calculation process is repeatedly executed by the battery pack control unit 150 from when the electric system S including the battery system 100 is started up until when it is shut down.

[0070] First, in step S11, the assembled battery control unit 150 calculates SOCi in the SOCi calculation unit 151-1 of the SOC calculation unit 151 according to the above formula (1). Next, in step S12, the assembled battery control unit 150 calculates SOCi in the SOCv calculation unit 151-2 of the SOC calculation unit 151 according to the above formulas (2) and (3). Next, in step S13, the assembled battery control unit 150 calculates SOC in the combination calculation unit 151-3 of the SOC calculation unit 151 according to the above formulas (4) and (5). The assembled battery control unit 150 stores the SOC calculated in step S13 in the variable SOC_old.

[0071] Next, in step S14, the battery pack control unit 150 determines in the internal resistance error detection unit 152-1 of the internal resistance calculation execution determination unit 152 whether the error of SOCv (the absolute value of the difference between SOC and SOCv) is equal to or greater than a predetermined value, and in the calculation execution determination unit 152-2, determines whether the input SOC, current, and temperature are all within predetermined ranges. If the determination result in step S14 is Yes in the correction possibility determination unit 152-3 of the internal resistance calculation execution determination unit 152, the battery pack control unit 150 determines that the internal resistance correction calculation is to be performed and proceeds to step S15, and if the determination result in step S14 is No, it determines that the internal resistance correction calculation is not to be performed and returns the process to step S11.

[0072] In step S15, the battery pack control unit 150, in an internal resistance correction amount calculation unit 153-1 of the SOH calculation unit 153, receives the SOC, SOCv, and current as inputs and calculates the internal resistance correction amount from the internal resistance correction amount map shown in Fig. 11. Next, in step S16, the battery pack control unit 150, in an internal resistance correction unit 153-2 of the SOH calculation unit 153, receives the determination result of the internal resistance calculation execution determination unit 152, the SOC, and the temperature as inputs and outputs the corrected internal resistance value Ro obtained by correcting the initial resistance value RoInit corresponding to the SOC and temperature in the internal resistance table 182 based on the first equation of the above equation (3) to the SOH calculation unit 153-3.

[0073] Next, in step S17, the battery pack control unit 150 calculates the SOH in the SOH calculation unit 153-3 from the above formula (6) based on the corrected internal resistance value Ro and the initial resistance value RoInit corresponding to the SOC and temperature. The battery pack control unit 150 stores the SOH calculated in step S18 in the variable SOH_old.

[0074] Next, in step S18, the battery pack control unit 150 determines whether the electric system S including the battery system 100 is to be shut down. If the electric system S is to be shut down (step S18: Yes), the SOH calculation process is terminated. If the electric system S is not to be shut down (step S18: No), the process returns to step S11.

[0075] Next, the effect of the first embodiment will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a diagram showing a profile of SOH calculation when charge / discharge pulses are input in the conventional technology. Fig. 14 is a diagram showing a profile of SOH calculation when charge / discharge pulses are input in the first embodiment.

[0076] Figures 13 and 14 respectively show waveforms of (a) the calculated SOC value, (b) the current, and (c) the calculated SOH (internal resistance rise rate) value when a rectangular charge / discharge current that repeats charging and discharging is input. Figure 13 shows the results of a conventional method (fixed resistance correction amount) before the present invention is applied, and Figure 14 shows the results when the present invention is applied. In Figures 13 and 14, the initial SOH value is set to 100%, and a state in which there is a large deviation from the true value is assumed.

[0077] Looking at the SOC waveform shown in Figure 13(a), in the region immediately after the start of charging and discharging, the waveform of the SOC based on the internal resistance (SOCv) deviates significantly from the calculated SOC value due to the influence of SOH calculation error (internal resistance error). At this point, the difference between SOCv and SOC is extracted, and the internal resistance is corrected to a fixed value while the calculated SOH value is gradually updated (Figure 13(c)). When the internal resistance is updated to a fixed value, SOCv approaches the calculated SOC value accordingly, that is, the SOC difference becomes smaller, and at the end of charging and discharging, the calculated SOH value converges to the true SOH value and the SOC difference also becomes smaller.

[0078] Next, the waveforms of SOC, current, and SOH when the present invention is applied are shown in FIG. 14. Looking at the waveform of SOC shown in FIG. 14(a), it can be seen that in the region immediately after the start of charging and discharging, the waveform of SOCv has a large deviation from SOC due to the influence of SOH error, as in the conventional technology shown in FIG. 13. Here, the difference between SOCv and SOC is extracted and the internal resistance is corrected. By using the resistance correction amount map shown in FIG. 11, the larger the SOC difference, the larger the internal resistance correction amount becomes, so that the update speed at which SOH approaches the true value is faster than in the conventional method. As the SOC difference decreases, the resistance correction amount becomes smaller, so the update speed at which SOH approaches the true value decreases, but it can be seen that the calculated value finally converges to the true value at about half the speed compared to the conventional method.

[0079] According to this embodiment, the internal resistance is corrected and the SOH is calculated using an internal resistance correction amount determined based on the current value and the difference between the SOC based on internal resistance (SOCv) and an SOC calculated using a method different from SOCv. This significantly improves the convergence of the SOH calculation compared to the conventional case in which the internal resistance correction amount is a fixed value, and makes it possible to maintain the SOH calculation accuracy (the difference between the final converged value and the true value) at the same level as the conventional case.

[0080] That is, by making the internal resistance value corrected according to the SOC difference and the current value variable, the resistance correction amount can be set large when the difference between the SOH recognized by the battery control device and the true SOH value of the controlled battery is large, improving the convergence of the SOH calculation value. Also, when the SOH calculation value is updated and approaches the true value, the correction amount of the internal resistance value becomes smaller, making it possible to calculate the SOH with high accuracy without compromising stability. As a result, it is possible to achieve both calculation accuracy and convergence, making it possible to accurately grasp the power that can be input and output to and from the battery, as well as to accurately calculate an index for battery replacement. EXAMPLES

[0081] Second Embodiment A second embodiment of the present invention will be described with reference to FIGS.

[0082] In the first embodiment, a method for controlling the correction amount of the internal resistance value based on the difference between the SOC calculated based on resistance (SOCv), the SOC calculated based on current (SOCi), and the SOC calculated by combining SOCv and the current value was described.

[0083] In this embodiment, an example will be described in which the temperature of the battery is further used to control the internal resistance correction amount. In the description of this embodiment, the differences from the first embodiment will be mainly described, and the description of the same configuration as the first embodiment will be omitted. The difference between this embodiment and the first embodiment is that the battery pack control unit 150 has a SOH calculation unit 153B instead of the SOH calculation unit 153. The SOH calculation unit 153B will be described below.

[0084] The SOH calculation unit 153B in this embodiment will be described with reference to Fig. 15. Fig. 15 is a block diagram showing the configuration of the SOH calculation unit 153B in the second embodiment. Compared to the SOH calculation unit 153 in the first embodiment, the SOH calculation unit 153B includes an internal resistance correction amount calculation unit 153-1B instead of the internal resistance correction amount calculation unit 153-1, and the battery temperature is added as an input. The internal resistance correction amount calculation unit 153-1B calculates an internal resistance correction amount using the SOC difference, current, and temperature as inputs, and outputs the amount to the internal resistance correction unit 153-2.

[0085] A method of calculating the internal resistance correction amount in the internal resistance correction amount calculation unit 153-1B will be described with reference to Fig. 16. Fig. 16 is a diagram showing an internal resistance correction amount map in the second embodiment, which shows the internal resistance correction amount according to the SOC difference for each temperature T.

[0086] Generally, the internal resistance of a battery tends to decrease with increasing temperature. For this reason, if a uniform internal resistance correction amount is set according to the temperature T, the internal resistance correction amount may be too large for the internal resistance value itself. When calculating the SOH as the ratio of the current internal resistance value to the internal resistance value when the battery is new, if the internal resistance correction amount is too large for the internal resistance value, the SOH value may fluctuate greatly and oscillate. Conversely, if the internal resistance correction amount is too small for the internal resistance value, the change in the SOH value will be small, and the convergence speed of the calculated SOH value to the true value may decrease.

[0087] Therefore, as in the resistance correction amount map shown in Fig. 16, the internal resistance correction amount is generally set to a small value in the high temperature region where the internal resistance value is small compared to the resistance correction amount map shown in Fig. 10, and conversely, the internal resistance correction amount is generally set to a large value in the low temperature region where the internal resistance value is large. That is, in this embodiment, the resistance correction amount map is constructed so that the internal resistance correction amount is set to a larger value the larger the difference between the SOC calculated value based on the internal resistance (SOCv) and the SOC calculated by a method other than SOCv, the smaller the absolute value of the current value, and the higher the battery temperature.

[0088] By constructing such a resistance correction amount map, it becomes possible to perform SOH calculation with assured convergence and stability for internal resistance values ​​that vary according to temperature.

[0089] The internal resistance correction amount according to the SOC difference, current, and temperature shown in FIG. 16 may be determined in advance as a map or table and stored in the memory unit 180, or the relationship may be described as a mathematical formula and implemented as the formula.

[0090] Next, the effects of this embodiment will be described with reference to FIGS.

[0091] 17 and 18 respectively show waveforms of (a) SOC calculation value, (b) current, and (c) SOH (internal resistance rise rate) calculation value when a rectangular charge / discharge current that repeats charging and discharging is input. Fig. 17 shows an example of the calculation result when SOH calculation is performed in a high temperature range (e.g., 50°C) using an internal resistance correction amount set in a normal temperature range (e.g., 25°C).

[0092] When calculating the SOH in the high temperature region where the internal resistance value is small, as shown in equation (6), even though the initial resistance value RoInit in the denominator is small compared to that at room temperature, when calculating the current internal resistance value Ro in the numerator, the calculated SOH value fluctuates greatly due to the large amount of internal resistance correction.In some cases, the calculated value may not converge near the true SOH value and may oscillate, as shown in Figure 17(c).

[0093] On the other hand, if an appropriate internal resistance correction amount is set for each temperature, that is, in the case of a high temperature region, the internal resistance correction amount is set to a smaller value and calculations are performed, it is possible to suppress vibrations near the true SOH value and to achieve calculations that ensure convergence, as shown in FIG. 18(c).

[0094] According to this embodiment, the internal resistance is corrected and the SOH is calculated using the difference between the SOC based on the internal resistance (SOCv) and an SOC calculated using a method different from SOCv, the current value, and an internal resistance correction amount determined according to the temperature, thereby making it possible to calculate an SOH that ensures stability and convergence even for internal resistance values ​​that vary depending on the temperature.

[0095] In this embodiment, the correction amount is adjusted by focusing on the fact that the internal resistance value varies depending on the temperature. However, the internal resistance value also varies depending on the deterioration level of the battery. Therefore, the internal resistance correction amount may be determined depending on the deterioration level. That is, as in the resistance correction amount map in the modified example of the second embodiment shown in FIG. 19, compared with the resistance correction amount map shown in FIG. 10, when the battery is new, the deterioration level SOH is small and the internal resistance is small, so the internal resistance correction amount is generally small, and as the deterioration progresses and the deterioration level SOH increases and the internal resistance increases, the internal resistance correction amount is generally large. Note that the internal resistance correction amount according to the SOC difference, current, and deterioration level shown in FIG. 19 may be determined in advance as a map or table and stored in the storage unit 180, or the relationship may be described as a formula and implemented as a formula.

[0096] That is, the resistance correction amount map is constructed so that the larger the difference between the SOC calculated based on the internal resistance (SOCv) and the SOC calculated by a method other than SOCv, the smaller the absolute value of the current value, and the greater the degree of deterioration of the battery, the larger the internal resistance correction amount is set to. This makes it possible to correct the internal resistance with an internal resistance correction amount appropriate for ensuring stability and convergence according to the degree of deterioration of the battery, and as a result, it becomes possible to achieve both stability and convergence of the SOH calculation value.

[0097] The above description is merely an example, and the present invention is not limited to the configuration of the above embodiment, and various modified examples are included. For example, the above embodiment has been described in detail to easily explain the present invention, and is not necessarily limited to the configuration having all the described configurations. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace other configurations with respect to a part of the configuration of each embodiment. In addition, the steps in the processing of each embodiment may be executed in an appropriate order as long as the same result can be obtained. [Explanation of symbols]

[0098] S... Electric system, 100... battery system, 110... assembled battery, 111... cell, 112... cell group, 120... cell management section, 121... cell control section, 122... voltage detection circuit, 123... control circuit, 124... signal input / output circuit, 125... temperature detection section, 130... current detection section, 140... voltage detection section, 150... assembled battery control section, 151... SOC calculation section, 151-1... SOCi calculation section, 151-2... SOCv calculation section, 151-3... combination calculation section, 152... internal resistance calculation section calculation execution determination unit, 152-1... internal resistance error detection unit, 152-2... calculation execution determination unit, 152-3... correction possibility determination unit, 152-4... current flow time measurement unit, 153... SOH calculation unit, 153-1... internal resistance correction amount calculation unit, 153-2... internal resistance correction unit, 153-3... SOH calculation unit, 160... signal communication unit, 170... insulation element, 180... storage unit, 200... vehicle control unit, 300, 310... relay, 400... inverter, 410... motor, 420... motor / inverter control unit

Claims

1. a first calculation unit that calculates a first state of charge of the battery using a first method based on a current value, a voltage value, and an internal resistance value of the battery; a second calculation unit that calculates a second state of charge of the battery by a second method different from the first method; an internal resistance calculation execution determination unit that determines that a correction calculation for the internal resistance can be executed when a difference between the first charge state and the second charge state is equal to or greater than a predetermined value; an internal resistance correction amount calculation unit that calculates an internal resistance correction amount according to an absolute value of a difference between the first charge state and the second charge state and an absolute value of the current value; an internal resistance correction unit that corrects the internal resistance value by the calculated resistance correction amount when the determination that the control can be performed is made; Including, The resistance correction amount is larger as the absolute value of the current value is smaller even if the absolute value of the difference is the same. A battery control device comprising:

2. 2. The battery control device according to claim 1, a deterioration degree calculation unit that calculates a deterioration degree of the battery based on the internal resistance value corrected by the internal resistance correction unit; A battery control device further comprising:

3. 2. The battery control device according to claim 1, the internal resistance correction unit further corrects the internal resistance value with the calculated resistance correction amount when the second charge state, the current value, and the temperature of the battery satisfy predetermined conditions. A battery control device comprising:

4. 4. The battery control device according to claim 3, when the difference is not detected or the second state of charge does not satisfy the predetermined condition, the internal resistance correction unit does not correct the internal resistance value, and outputs the internal resistance value corrected in the most recent calculation cycle in which the difference was detected and it was determined that the second state of charge, the current value, and the temperature of the battery satisfy the predetermined condition. A battery control device comprising:

5. 2. The battery control device according to claim 1, The resistance correction amount is larger as the absolute value of the difference is larger and as the absolute value of the current value is smaller. A battery control device comprising:

6. 6. The battery control device according to claim 5, The resistance correction amount is a value that is further determined according to the temperature of the battery. A battery control device comprising:

7. 7. The battery control device according to claim 6, The resistance correction amount is smaller as the temperature of the battery is higher. A battery control device comprising:

8. 6. The battery control device according to claim 5, The resistance correction amount is a value according to a deterioration degree of the battery. A battery control device comprising:

9. 9. The battery control device according to claim 8, The resistance correction amount is larger as the degree of deterioration of the battery increases. A battery control device comprising:

10. A battery control device according to any one of claims 1 to 9, a battery pack in which a plurality of the batteries are connected and controlled by the battery control device; A battery system comprising:

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