Battery state calculation device, program, and method for controlling battery state calculation device

Abstract

A battery state calculation device (20, 120, 220) comprises an AC drive unit (42, 51, 56, 60, 130, 131), a voltage detection circuit (31 to 33) for detecting the inter-terminal voltage of a storage battery (10, 1000), a current detection circuit (43, 52 to 54) for detecting current, and a computation unit (70, 93). The computation unit: acquires values detected by the voltage detection circuit and the current detection circuit when an AC current is being channeled by the AC drive unit; calculates the complex impedance of the storage battery on the basis of the acquired detection values; calculates, on the basis of the calculated complex impedance of the storage battery and the complex impedance of a reference battery to be compared with the calculated complex impedance of the storage battery, a corrective value (ΔZkA, ΔZkB, ΔZkC, ΔZkD) for correcting the relative error of the calculated complex impedance of the storage battery with respect to the complex impedance of the reference battery; and corrects the calculated complex impedance of the storage battery on the basis of the calculated corrective value.

Description

Battery state calculation device, program, and method for controlling battery state calculation device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-109553, filed on July 8, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a battery state calculation device, a program, and a control method for a battery state calculation device.

[0003] 2. Description of the Related Art Conventionally, a battery state calculation device that calculates the complex impedance of a storage battery is known, as described in, for example, Patent Document 1.

[0004] International Publication No. 2023 / 162751

[0005] A system to which a battery state calculation device is applied includes a system that includes an electrical path that electrically connects a positive terminal of a storage battery and a negative terminal of the storage battery.

[0006] The device includes an AC driving unit that applies AC current to a closed circuit including an electrical path and a storage battery, a voltage detection circuit, a current detection circuit that detects the current flowing in the closed circuit, and a calculation unit. The voltage detection circuit is connected in parallel to the storage battery and detects the voltage between the terminals of the storage battery.

[0007] The calculation unit acquires the detection values ​​of the voltage detection circuit and the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit, and calculates the complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit.

[0008] To determine the state (e.g., degradation state) of a storage battery, the calculated complex impedance of the storage battery may be compared with the complex impedance of a reference battery, and the complex impedance of the reference battery is also calculated using the above-described method.

[0009] When an AC current flows through the closed circuit, a magnetic flux is generated. This magnetic flux may cause errors in the detected values ​​of the voltage detection circuit and the voltage detection circuit. In this case, the difference between the error contained in the complex impedance of the storage battery and the error contained in the complex impedance of the reference battery may become large.

[0010] The main object of the present disclosure is to provide a battery state calculation device, a program, and a control method for a battery state calculation device that can reduce the difference between the error contained in the complex impedance of a storage battery and the error contained in the complex impedance of a reference battery.

[0011] The present disclosure provides a battery state calculation device applicable to a system having an electrical path electrically connecting a positive terminal of a storage battery and a negative terminal of the storage battery, the device comprising: an AC drive unit that causes an AC current to flow through a closed circuit including the electrical path and the storage battery; a voltage detection circuit that is connected in parallel to the storage battery and detects a voltage between the terminals of the storage battery; a current detection circuit that detects a current flowing through the closed circuit; and a calculation unit.

[0012] In the present disclosure, the calculation unit: acquires the detection value of the voltage detection circuit and the detection value of the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit; calculates the complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; calculates a correction value for correcting a relative error of the calculated complex impedance of the storage battery with respect to the complex impedance of the reference battery based on the complex impedance of a reference battery to be compared with the calculated complex impedance of the storage battery; and corrects the calculated complex impedance of the storage battery based on the calculated correction value.

[0013] This reduces the relative error of the complex impedance of the storage battery relative to the complex impedance of the reference battery, and reduces the difference between the error included in the complex impedance of the storage battery and the error included in the complex impedance of the reference battery, thereby improving the accuracy of battery information (e.g., deterioration state) obtained by comparing the complex impedances of the reference battery and the storage battery.

[0014] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a diagram illustrating the overall configuration of a battery state calculation device according to a first embodiment, Fig. 2 is a diagram illustrating a voltage detection closed circuit and a current detection closed circuit, Fig. 3 is a diagram illustrating a case in which the impedance of the same storage battery is measured by first and second battery state calculation devices, Fig. 4 is a flowchart illustrating a procedure for impedance correction processing, Fig. 5 is a diagram illustrating the relationship between the angular frequency of a reference signal and a correction value, Fig. 6 is a diagram illustrating a Cole-Cole plot before correction, Fig. 7 is a diagram illustrating a Cole-Cole plot before and after correction for amplitude and phase effects in the first battery state measurement device, and Fig. 8 is a diagram illustrating amplitude and phase effects in the second battery state measurement device.16 is a diagram showing the overall configuration of a battery state calculation device according to a third embodiment; FIG. 17 is a flowchart showing the procedure of impedance correction processing; FIG. 18 is a diagram showing the overall configuration of a battery state calculation device according to a third embodiment; FIG. 19 is a diagram showing the internal configuration of the module shown in FIG. 18; and FIG. 20 is a diagram showing the overall configuration of a battery state calculation device according to a third embodiment; 21 is an overall configuration diagram of a battery state calculation device according to a modification of the third embodiment, FIG. 22 is a plan view of a battery pack according to a modification of the third embodiment, FIG. 23 is a diagram showing an example of a calculation result of mutual inductance, FIG. 24 is a plan view of a battery pack according to a modification of the third embodiment, FIG. 25 is a diagram showing an example of a calculation result of mutual inductance, FIG. 26 is a diagram showing an example of a calculation result of mutual inductance, FIG. 27 is a flowchart showing a procedure for impedance correction processing according to the fourth embodiment, FIG. 28 is a diagram showing an outline of a correction method according to another embodiment, FIG. 29 is a diagram showing an outline of a correction method according to another embodiment, FIG. 30 is a diagram showing the configuration of a voltage and current detection unit according to another embodiment, FIG. 31 is a diagram showing an arrangement of an electrical path according to another embodiment, and FIG. 32 is a diagram showing an arrangement of an electric circuit according to another embodiment.

[0015] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0016] First Embodiment A first embodiment of a battery state calculation device according to the present disclosure will now be described with reference to the drawings.

[0017] The battery state calculation device 20 is a device that calculates the state of the storage battery 10, and specifically, is a device that measures the internal impedance of the storage battery 10. Based on the measured internal impedance, the storage battery 10's state of charge (specifically, SOC) and state of health (SOH), etc. are calculated. In this embodiment, the storage battery 10 is a chargeable and dischargeable secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery. The storage battery 10 is one unit battery or a series connection of multiple unit batteries. The unit battery is one battery cell or a series connection of multiple battery cells.

[0018] The battery state calculation device 20 includes a voltage processing unit 30. The voltage processing unit 30 is configured as an integrated circuit (IC) and includes a positive voltage path 31, a negative voltage path 32, and a voltage detection unit 33. A positive voltage terminal 31a, which is a first end of the positive voltage path 31, is connected to the positive terminal 10a of the storage battery 10, and a second end of the positive voltage path 31 is connected to the voltage detection unit 33. A negative voltage terminal 32a, which is a first end of the negative voltage path 32, is connected to the negative terminal 10b of the storage battery 10, and a second end of the negative voltage path 32 is connected to the voltage detection unit 33. The voltage detection unit 33 detects the voltage difference between the positive voltage path 31 and the negative voltage path 32 as the terminal voltage of the storage battery 10. In this embodiment, the voltage processing unit 30, the positive voltage path 31, and the negative voltage path 32 correspond to a "voltage detection circuit."

[0019] The battery state calculation device 20 includes a limiting resistor 41, a current control switch 42, a shunt resistor 43, a current processing unit 50, a positive electrode side current path 53, a negative electrode side current path 54, and a reference signal generation unit 60 as components for generating and detecting the current flowing through the storage battery 10.

[0020] A first end of the limiting resistor 41 is connected to a first end of the positive electrode connecting portion 40a. A second end of the positive electrode connecting portion 40a is connected to the positive electrode terminal 10a of the storage battery 10. A first end of a shunt resistor 43 is connected to the second end of the limiting resistor 41 via a current control switch 42. In this embodiment, the current control switch 42 is an N-channel MOSFET. A first end of the negative electrode connecting portion 40b is connected to the second end of the shunt resistor 43. A second end of the negative electrode connecting portion 40b is connected to the negative electrode terminal 10b of the storage battery 10. In this embodiment, the second end of the positive electrode connecting portion 40a is configured to be detachably connected to the positive electrode terminal 10a, and the second end of the negative electrode connecting portion 40b is configured to be detachably connected to the negative electrode terminal 10b.

[0021] Alternatively, the positive voltage path 31 may be connected to the second end of the positive connection portion 40a, and the negative voltage path 32 may be connected to the second end of the negative connection portion 40b. In this case, when the second end of the positive connection portion 40a is connected to the positive terminal 10a, the positive voltage path 31 is electrically connected to the positive terminal 10a. When the second end of the negative connection portion 40b is connected to the negative terminal 10b, the negative voltage path 32 is electrically connected to the negative terminal 10b. The arrangement order of the limiting resistor 41, the current control switch 42, and the shunt resistor 43 between the positive connection portion 40a and the negative connection portion 40b is not limited to the order shown in FIG. 1 .

[0022] The current processing section 50 is configured as an integrated circuit (IC) and includes a current modulation section 51 and a current detection section 52 .

[0023] The battery state calculation device 20 includes a positive current path 53, a negative current path 54, and a reference signal generation unit 60. The positive current path 53 connects a first end of the shunt resistor 43 to a current detection unit 52. The negative current path 54 connects a second end of the shunt resistor 43 to the current detection unit 52. The current detection unit 52 detects the voltage difference between the positive current path 53 and the negative current path 54 as the current flowing through the storage battery 10. The current detected by the current detection unit 52 is input to a current modulation unit 51.

[0024] The current modulation unit 51 is a circuit that inputs a predetermined AC signal to the storage battery 10 that is the measurement target. The reference signal generation unit 60 generates a sine wave reference signal and inputs the generated reference signal to the current modulation unit 51. The current modulation unit 51 controls the gate voltage of the current control switch 42 to control the current detected by the current detection unit 52 to a sine wave target current that fluctuates with the frequency of the reference signal. The AC current is, for example, the charging current or discharging current of the storage battery 10. Note that the target current may be a rectangular wave signal instead of a sine wave signal.

[0025] In this embodiment, the current control switch 42, the current modulation unit 51, and the reference signal generation unit 60 correspond to an "AC drive unit." The shunt resistor 43, the current detection unit 52, the positive current path 53, and the negative current path 54 correspond to a "current detection circuit."

[0026] 1 shows an equivalent circuit model of the complex impedance of a storage battery 10. In this equivalent circuit model, the internal complex impedance of the storage battery 10 is composed of a series connection of an ohmic resistance 11 and a reaction resistance 12. The ohmic resistance 11 is a current-carrying resistance in the electrodes and electrolyte that constitute the storage battery 10. The reaction resistance 12 represents a resistance due to an electrode interface reaction in the electrodes, and is represented as a parallel connection of a resistance component 12a and a capacitance component 12b.

[0027] The battery state calculation device 20 includes a temperature sensor 80 and a pressure sensor 81. The temperature sensor 80 detects the temperature of the storage battery 10. The pressure sensor 81 detects the pressure of the storage battery 10 (for example, internal pressure).

[0028] The battery state calculation device 20 includes a control device 70. The control device 70 is an electronic control unit (ECU), and includes, as hardware, a processor 71 and a storage unit 72. In the control device 70, the processor 71 and the storage unit 72 are connected to each other via a communication bus 73.

[0029] The memory unit 72 includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the control device 70. The memory provides the processor 71 with a working area for temporary use when the processor 71 performs processing, for example. The memory includes, for example, a ROM or a RAM. The storage is a storage device for storing various programs and data to be read and executed by the processor 71, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or a flash memory. The storage stores program information and the like for processing, such as that shown in FIG. 4, which will be described later.

[0030] For example, program information stored on a non-transient physical recording medium is installed in the storage unit 72. The recording medium is, for example, a USB memory, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as over the air (OTA), is installed in the storage unit 72.

[0031] The control device 70 receives detection values ​​from the voltage detection unit 33, the current detection unit 52, the temperature sensor 80, and the pressure sensor 81. The control device 70 inputs a reference signal generation command to the reference signal generation unit 60. The control device 70, functioning as a "calculation unit," calculates information about the complex impedance (Zm) of the storage battery 10 based on the detection values ​​from the voltage detection unit 33 and the current detection unit 52. That is, the control device 70 calculates the real part of the complex impedance (ReZm) and the imaginary part of the complex impedance (ImZm) based on the detection values ​​from the voltage detection unit 33 and the current detection unit 52. The control device 70 creates, for example, a complex impedance plane plot (Cole-Cole plot) based on the calculation results to determine the characteristics of the electrodes, electrolyte, and the like. For example, the control device 70 determines the state of charge (SOC) and the state of health (SOH).

[0032] 2 shows a voltage detection closed circuit 34 and a current detection closed circuit 55. The voltage detection closed circuit 34 is a closed circuit including a positive electrode side voltage path 31, a path from the positive electrode terminal 10a to the negative electrode terminal 10b of the storage battery 10, a negative electrode side voltage path 32, and a voltage detection unit 33. The current detection closed circuit 55 is a closed circuit including a shunt resistor 43, a positive electrode side current path 53, a current detection unit 52, and a negative electrode side current path 54.

[0033] When AC current flows through the storage battery 10 under the control of the current modulation unit 51, a magnetic field is generated. When the generated magnetic field interlinks with the voltage detection closed circuit 34, an induced electromotive force is generated in the voltage detection closed circuit 34. In this case, a detection error occurs in the voltage detected by the voltage detection unit 33 via the positive voltage path 31 and the negative voltage path 32.

[0034] Furthermore, when a magnetic field generated by the flow of AC current intersects with the current detection closed circuit 55, an induced electromotive force is generated in the current detection closed circuit 55. In this case, a detection error occurs in the current detected by the current detection unit 52 via the positive current path 53 and the negative current path 54. If the detection values ​​of the voltage detection unit 33 and the current detection unit 52 contain detection errors, there is a concern that the calculation accuracy of the complex impedance of the storage battery 10 will decrease.

[0035] The effect of detection error depends on the relative positions of each element constituting the battery state calculation device 20. Even for the same storage battery, the complex impedances calculated by two battery state calculation devices with different relative positions may differ. For example, as shown in FIG. 3 , assume that the relative positions of components are different between a first battery state calculation device 20A owned by a first organization (e.g., a research institute) and a second battery state calculation device 20B owned by a second organization (e.g., a manufacturer) different from the first organization. In this case, even if the storage battery 10 being measured by the first battery state calculation device 20A and the second battery state calculation device 20B is the same storage battery 10, the complex impedance calculated by the first battery state calculation device 20A will differ from the complex impedance calculated by the second battery state calculation device 20B. In this case, the complex impedances calculated by the respective organizations cannot be accurately compared. Therefore, the present embodiment employs a technique that enables accurate comparison.

[0036] First, the principle of comparison will be explained.

[0037] The current fluctuation Is actually flowing through the storage battery 10 is expressed by the following equation (eq1): In the following equation (eq1), I0 represents the amplitude of the current actually flowing through the storage battery 10, Δα represents the phase difference of the current Is relative to the reference signal of the reference signal generating unit 60, and j represents the imaginary unit.

[0038] The actual terminal voltage fluctuation of the storage battery 10 that occurs when a current Is flows through the storage battery 10 is expressed by the following equation (eq2): In the following equation (eq2), Zb represents the true complex impedance of the storage battery 10.

[0039] The inter-terminal voltage fluctuation Vm of the storage battery 10 detected by the voltage detection unit 33 is expressed by the following equation (eq3): In the following equation (eq3), ω0 represents the angular frequency of the reference signal, and Mv represents the mutual inductance between the main closed circuit and the current detection closed circuit 55. The main closed circuit is a closed circuit that includes a path from the positive terminal 10a to the negative terminal 10b of the storage battery 10, the positive electrode connection part 40a, the limiting resistor 41, the current control switch 42, the shunt resistor 43, and the negative electrode connection part 40b. Δβ represents the phase difference of the inter-terminal voltage fluctuation Vm with respect to the reference signal.

[0040] The current fluctuation Im of the storage battery 10 detected by the current detection unit 52 is expressed by the following equation (eq4): In the following equation (eq4), Mi represents the mutual inductance between the main closed circuit and the current detection closed circuit 55. Rs represents the resistance value of the shunt resistor 43, and Δγ represents the phase difference of the current fluctuation Im with respect to the reference signal.

[0041] When the above equation (eq4) is solved for Im, the following equation (eq5) is derived.

[0042] The complex impedance Zm of the storage battery calculated based on the detected voltage and current fluctuations Vm and Im is expressed by the following equation (eq6).

[0043] The above equation (eq6) is a correction equation that includes the influence of mutual inductance and the influence of phase delay. When the above equation (eq6) is solved for Zb, the following equation (eq7) is derived.

[0044]

[0045]

[0046]

[0047] The true complex impedance Zb is obtained by applying the amplitude influence coefficient Kamp shown in the above equation (eq8), the phase influence coefficient Kph shown in the above equation (eq9), and the intercept Intspt shown in the above equation (eq10) to the complex impedance Zm based on the detected current and voltage fluctuations Im and Vm.

[0048] The mutual inductance Mi can be calculated, for example, by simulation using magnetic field analysis, by calculating θp or Kamp for two or more Rs and creating simultaneous equations, or by fitting.

[0049] In the case of errors caused by white noise or unwanted signals, the errors can be reduced by increasing the measurement current to increase the S / N ratio. In contrast, the amplitude influence coefficient Kamp, the phase influence coefficient Kph, and the intercept Intspt are all independent of the measurement current. In other words, these errors cannot be reduced by increasing the measurement current. For this reason, the impedance correction process described below is required.

[0050] The following describes a case where the state of the same storage battery 10, whose true complex impedance is Zt, is measured by the first battery state calculation device 20A and the second battery state calculation device 20B. In the formulas that have appeared so far, the detected values ​​and calculated values ​​in the first battery state calculation device 20A are given a subscript A, and the detected values ​​and calculated values ​​in the second battery state calculation device 20B are given a subscript B.

[0051] Referring to the above equation (eq7), the following equation (eq11) holds in the first battery state calculation device 20A, and the following equation (eq12) holds in the second battery state calculation device 20B.

[0052]

[0053] The following equation (eq13) can be derived from the above equations (eq11) and (eq12).

[0054] The above equation (eq13) becomes the following equation (eq14) when the amplitude influence coefficient Kamp and the phase influence coefficient Kph are used.

[0055] The left side of the above equation (eq14) will be explained. ZmB is a complex impedance calculated based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52 in the second battery state calculation device 20B. KampB is an amplitude influence coefficient determined from the angular frequency ω0 of the reference signal, the mutual inductance Mi between the main closed circuit and the current detection closed circuit 55, and the resistance value Rs of the shunt resistor 43, as shown in the above equation (eq8). KphB is a phase influence coefficient determined from the angular frequency ω0 of the reference signal, the mutual inductance Mi between the main closed circuit and the current detection closed circuit 55, the resistance value Rs of the shunt resistor 43, and the respective phase differences Δβ and Δγ, as shown in the above equations (eq9) and (eq7). In other words, the amplitude influence coefficient KampB and the phase influence coefficient KphB are coefficients determined by the second battery state calculation device 20B.

[0056] The right side of equation (eq14) above will be explained. ZmA is a complex impedance calculated based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52 in the first battery state calculation device 20A. KampA is an amplitude influence coefficient determined from the angular frequency ω0 of the reference signal, the mutual inductance Mi between the main closed circuit and the current detection closed circuit 55, and the resistance value Rs of the shunt resistor 43, as shown in equation (eq8) above. KphA is a phase influence coefficient determined from the angular frequency ω0 of the reference signal, the mutual inductance Mi between the main closed circuit and the current detection closed circuit 55, the resistance value Rs of the shunt resistor 43, and the phase differences Δβ and Δγ, as shown in equations (eq9) and (eq7) above. In other words, the amplitude influence coefficient KampA and the phase influence coefficient KphA are coefficients determined by the first battery state calculation device 20A.

[0057] The difference between "ZmB x KampB x KphB" and "ZmA x KampA x KphA" is the error in the complex impedance due to the difference in the device configuration (e.g., the above-mentioned relative position) of the first and second battery state calculation devices 20A, 20B. By performing a correction such that one of "ZmB x KampB x KphB" and "ZmA x KampA x KphA" approaches the other, the relative error in the complex impedance due to the difference in the device configuration of the two devices can be reduced.

[0058] FIG. 4 is a flowchart of the impedance correction process executed by the control device 70.

[0059] Steps S10 to S13 are processes executed by the control device 70 of the first battery state calculation device 20A.

[0060] First, the positive terminal 10a and the negative terminal 10b of the storage battery 10 are connected to the positive electrode connection part 40a and the negative electrode connection part 40b of the first battery state calculation device 20A. The first battery state calculation device 20A may include a thermostatic bath in which the storage battery 10 is housed.

[0061] When the storage battery 10 is connected to the positive electrode connection portion 40a and the negative electrode connection portion 40b, the relative positions of the storage battery 10, the positive electrode connection portion 40a, the negative electrode connection portion 40b, the limiting resistor 41, the current control switch 42, the shunt resistor 43, the negative electrode connection portion 40b, the voltage detection closed circuit 34, and the current detection closed circuit 55 are fixed in the first battery state calculation device 20A.

[0062] In step S10, it is determined whether a temperature condition is met. The temperature condition is a condition that the detected temperature Tbr of the temperature sensor 80 is equal to the target temperature Ttgt, or a condition that the detected temperature Tbr is equal to the target temperature Ttgt. For example, the detected temperature Tbr being equal to the target temperature Ttgt means "Ttgt - 5°C ≦ Tbr ≦ Ttgt + 5°C," "Ttgt - 3°C ≦ Tbr ≦ Ttgt + 3°C," "Ttgt - 1°C ≦ Tbr ≦ Ttgt + 1°C," or "Ttgt - 0.5°C ≦ Tbr ≦ Ttgt + 0.5°C."

[0063] If it is determined that the temperature condition is met, the process proceeds to step S11, where it is determined whether the voltage condition is met. The voltage condition is a condition that the detected voltage Vbr of the voltage detection unit 33 is equal to the target voltage Vtgt (e.g., the rated voltage of the storage battery 10) when no current is flowing through the storage battery 10, or a condition that the detected voltage Vbr is equivalent to the target voltage Vtgt. The detected voltage Vbr being equivalent to the target voltage Vtgt means, for example, "0.997×Vtgt≦Vbr≦1.003×Vtgt," "0.999×Vtgt≦Vbr≦1.001×Vtgt," or "0.9997×Vtgt≦Vbr≦1.0003×Vtgt."

[0064] In addition, the voltage condition may be the SOC of the storage battery 10 instead of the detected voltage Vbr. In addition to the temperature and voltage conditions, a pressure condition of the storage battery 10 may be added. The pressure condition is a condition that the detected pressure of the pressure sensor 81 is the target pressure, or a condition that the detected pressure is equal to the target pressure.

[0065] If it is determined in step S11 that the voltage condition is met, the process proceeds to step S12, where a reference signal generation command is input to the reference signal generation unit 60 so that the current control switch 42 is controlled by the current modulation unit 51 included in the first battery state calculation device 20A. Here, a frequency sweep is performed to gradually change (gradually increase or decrease) the angular frequency ω0 of the reference signal. As a result, an AC current fluctuating with the frequency ω0 of the reference signal flows through the storage battery 10. While the AC current is flowing, the current detection unit 52 acquires the detected current ImA, and the voltage detection unit 33 acquires the detected voltage VmA. Specifically, the detected current ImA and detected voltage VmA corresponding to the angular frequency are acquired.

[0066] In step S13, the complex impedance ZmA (=VmA / ImA) of the storage battery 10 is calculated based on the acquired detected current ImA and detected voltage VmA. Then, the calculated complex impedance ZmA is multiplied by the amplitude influence coefficient KampA and the phase influence coefficient KphA in the first battery state calculation device 20A to calculate "ZmA×KampA×KphA".

[0067] The amplitude influence coefficient KampA and the phase influence coefficient KphA are values ​​calculated in advance, for example, by experiment or calculation, and are stored in the storage unit 72. The control device 70 reads out from the storage unit 72 and uses the amplitude influence coefficient KampA and the phase influence coefficient KphA used in calculating "ZmA×KampA×KphA".

[0068] Steps S14 to S19 are processes executed by the control device 70 of the second battery state calculation device 20B.

[0069] The storage battery 10 that has become the measurement target of the first battery state calculation device 20A is transported from the first organization to the second organization. The positive electrode connector 40a and the negative electrode connector 40b of the second battery state calculation device 20B are connected to the positive electrode terminal 10a and the negative electrode terminal 10b of the transported storage battery 10. The second battery state calculation device 20B may include a thermostatic bath in which the storage battery 10 is accommodated.

[0070] When the storage battery 10 is connected to the positive electrode connection portion 40a and the negative electrode connection portion 40b, the relative positions of the storage battery 10, the positive electrode connection portion 40a, the negative electrode connection portion 40b, the limiting resistor 41, the current control switch 42, the shunt resistor 43, the negative electrode connection portion 40b, the voltage detection closed circuit 34, and the current detection closed circuit 55 are fixed in the second battery state calculation device 20B.

[0071] In step S14, it is determined whether or not the temperature conditions are met. The temperature conditions are the same as those in step S10.

[0072] If it is determined that the temperature condition is met, the process proceeds to step S15, where it is determined whether or not the voltage condition is met. The voltage condition is the same as the condition in step S11.

[0073] If it is determined that the voltage condition is met, the process proceeds to step S16, where a reference signal generation command is input to the reference signal generation unit 60 so that the current control switch 42 is controlled by the current modulation unit 51 included in the second battery state calculation device 20B. Here, a frequency sweep is performed to gradually change (gradually increase or decrease) the angular frequency ω0 of the reference signal. As a result, an AC current fluctuating with the frequency ω0 of the reference signal flows through the storage battery 10. While the AC current is flowing, the current detection unit 52 acquires the detected current ImB, and the voltage detection unit 33 acquires the detected voltage VmB. Specifically, the detected current ImB and detected voltage VmB corresponding to the angular frequency are acquired.

[0074] In step S17, the complex impedance ZmB (=VmB / ImB) of the storage battery 10 is calculated based on the detected current ImB and the detected voltage VmB. Then, the calculated complex impedance ZmB is multiplied by the amplitude influence coefficient KampB and the phase influence coefficient KphB in the second battery state calculation device 20B to calculate "ZmB×KampB×KphB".

[0075] The amplitude influence coefficient KampB and the phase influence coefficient KphB are values ​​calculated in advance, for example, by experiment or calculation, and are stored in the storage unit 72. The control device 70 reads out from the storage unit 72 the amplitude influence coefficient KampB and the phase influence coefficient KphB used to calculate "ZmB × KampB × KphB".

[0076] In step S18, a correction value ΔZ (= j × ω0 × (MvA - MvB)) is calculated by subtracting "ZmA × KampA × KphA" calculated in step S13 from "ZmB × KampB × KphB" calculated in step S17. The correction value ΔZ is a value for correcting the imaginary part of the complex impedance. The correction value ΔZ becomes larger as the angular frequency ω0 becomes higher. The calculated correction value ΔZ is associated with the frequency ω0 and stored in the memory unit 72.

[0077] The information stored in the storage unit 72 may be table information or formula information in which the frequency ω0 and the correction value ΔZ are linked. In the case of formula information, the formula used may be, for example, a polynomial, an exponential function, a trigonometric function, or a combination of these functions.

[0078] Incidentally, the following equation (eqA) can be derived from the above equation (eq14).

[0079] FIG. 5 shows the relationship between angular frequency ω0 and correction value ΔZ. The error in mutual inductance in impedance measurement is proportional to angular frequency ω0, and the difference in mutual inductance is the proportionality constant. Measurements are taken at two or more frequencies, and the difference in mutual inductance can be calculated by solving a linear equation or by fitting. Since the relationship between angular frequency ω0 and correction value ΔZ theoretically passes through the origin, it is preferable to fit using an equation that passes through the origin. Furthermore, using measurements on the higher frequency side increases ΔZ, improving the accuracy of ΔZ. Ideally, it is desirable to avoid extrapolation within the measurement frequency range. When fitting, there are methods that do not fix the intercept, and methods that set the intercept to 0 (passing through the origin). Note that the number of frequencies measured is not limited to multiple, and may be a single frequency. In this case, the proportionality constant (slope) can be calculated assuming that the intercept passes through the origin.

[0080] In step S19, "ZmB x KampB x KphB" calculated in step S17 is corrected based on the calculated correction value ΔZ. Specifically, the correction value ΔZ is subtracted from "ZmB x KampB x KphB".

[0081] The correction value ΔZ stored in step S18 is used when the complex impedance is calculated by the second battery state calculation device 20B owned by the second organization.

[0082] It should be noted that, instead of correcting "ZmB×KampB×KphB" calculated by the second battery state calculation device 20B, it is also possible to correct "ZmA×KampA×KphA" calculated by the first battery state calculation device 20A. More specifically, in step S19, the control device 70 of the first battery state calculation device 20A corrects "ZmA×KampA×KphA" by adding the correction value ΔZ calculated in step S18 to "ZmA×KampA×KphA" calculated in step S13.

[0083] It is also possible to correct both "ZmA x KampA x KphA" and "ZmB x KampB x KphB" calculated by the first and second battery state calculation devices 20A, 20B. Specifically, in step S18, ΔZ / 2 is calculated as a correction value. In step S19, the control device 70 of the first battery state calculation device 20A corrects "ZmA x KampA x KphA" by adding the calculated correction value ΔZ / 2 to "ZmA x KampA x KphA" calculated in step S13. Furthermore, the control device 70 of the second battery state calculation device 20B corrects "ZmB x KampB x KphB" by subtracting the correction value ΔZ / 2 from "ZmB x KampB x KphB" calculated in step S17.

[0084] Incidentally, the relative position of the first battery state calculation device 20A in steps S10 to S13 and the relative position of the second battery state calculation device 20B in steps S14 to S17 may be the same or different.

[0085] 6 to 9, the manner in which "ZmA x KampA x KphA" calculated by the first battery state calculation device 20A is corrected will be described.

[0086] 6 shows the complex impedances ZmA and ZmB calculated in steps S13 and S17. The complex impedances ZmA and ZmB are sets of complex impedances associated with the respective angular frequencies ω0 of the reference signal.

[0087] Fig. 7 shows "ZmA" and "ZmA x KampA x KphA" in step S13, and Fig. 8 shows "ZmB" and "ZmB x KampB x KphB" in step S17.

[0088] FIG. 9 shows "ZmB×KampB×KphB" and the corrected "ZmA×KampA×KphA".

[0089] According to the present embodiment described above, it is possible to reduce the relative error of the complex impedance calculated by the second battery state calculation device 20B with respect to the complex impedance calculated by the first battery state calculation device 20A, thereby reducing the difference in error contained in the complex impedances calculated by the devices 20A and 20B.

[0090] The degree to which the magnetic flux generated by the AC current flowing through the main closed circuit affects the detected values ​​of the voltage detection unit 33 and the current detection unit 52 changes when the relative positions of the components of the battery state calculation device 20 change. Conversely, the degree to which the magnetic flux generated by the AC current flowing through the main closed circuit affects the detected values ​​of the voltage detection unit 33 and the current detection unit 52 is small when the relative positions are fixed. This point will be explained below using Figures 10 and 11. Figure 10 is a conceptual diagram of Faraday's law. Figure 11 is a reference diagram of Biot-Savart's law.

[0091] Faraday's law is shown in the following equation (eqB). In the following equation (eqB), "E(x, t)" represents the electric field vector, and "L" represents the path of the line integral. "B(x, t)" represents the magnetic flux density vector. "S" represents the area enclosed by the path of the line integral on the left side. "n" represents the normal vector of a point on "S". "x" is a vector indicating the position from the current element, and "t" represents time. In other words, the electric field vector "E(x, t)" and the magnetic flux density vector "B(x, t)" are values ​​that depend on location and time. "Vi(t)" represents the induced electromotive force.

[0092] When a current I flows through an arbitrary closed circuit C0, the magnetic flux density B generated at an arbitrary point P by a current element I×ds is expressed by the following equation (eqC) according to the Biot-Savart law using vectors s and x starting from an arbitrary point O. Here, "t" represents time, "μ0" represents the magnetic permeability of a vacuum, and "μr(x)" represents the relative magnetic permeability.

[0093] Substituting the above equation (eqC) into the above equation (eqB), the following equation (eqD) is derived.

[0094] The total time derivative d / dt on the right-hand side of the above equation (eqD) can be expressed using partial derivatives for each parameter. For example, if it depends on the time t and the position x, the following equation (eqE) is derived:

[0095] The second term on the right side of the above equation (eqE) represents, for example, an induced electromotive force that occurs when the position of the voltage detection closed circuit 34 (see FIG. 2) changes over time. If dz / dt is a periodic function with frequency f, an induced electromotive force that fluctuates with frequency f is generated. Similarly, if the parameter used for partial differentiation is, for example, the position s of the closed circuit through which current flows (specifically, for example, the main closed circuit), the second term on the right side of the above equation (eqE) can also represent an induced electromotive force when s changes over time, and if s is periodic, an induced electromotive force is generated at a frequency corresponding to the period. The same applies to the other parameters.

[0096] Here, focusing on the first term on the right side of the above equation (eqE), if only the current I(t) depends on time, the following equation (eqF) is derived.

[0097] The underlined portion of the above equation (eqF) is the mutual inductance M between the voltage fluctuation measurement path L (specifically, the voltage detection closed circuit 34) and the current measurement path C0 (specifically, the current detection closed circuit 55). From the above equation (eqF), it can be seen that when the shapes of the voltage detection closed circuit 34 and the current detection closed circuit do not change and the magnetic permeability μr(x) is constant, the mutual inductance M becomes a constant value and does not change. When calculating the correction value, it is important to fix the current detection closed circuit 55 and the voltage detection closed circuit 34.

[0098] In consideration of this, an AC current is passed through the main closed circuit while the relative positions are fixed. The control device 70 acquires the detection values ​​of the voltage detection unit 33 and the current detection unit 52 when the AC current is passing through the main closed circuit, and calculates the complex impedance based on the acquired detection values.

[0099] The degree of change in the relative error of the complex impedance calculated by the second battery state calculation device with respect to the complex impedance calculated by the first battery state calculation device 20A is small if the relative position is fixed. Therefore, according to this embodiment, it is possible to improve the accuracy of calculation of the correction value for reducing the relative error.

[0100] <Modification of First Embodiment> When the resistance value Rs of the shunt resistor 43 is large with respect to the mutual inductance Mi (see equation (eq8) above), the amplitude influence coefficients KampA and KampB used in the impedance correction process may be set to 1.

[0101] The energy source of the current for impedance measurement is not limited to the storage battery 10 to be measured, and may be, for example, a commercial power supply 17 as shown in FIG. 12 . The battery state calculation device 21 includes an AC power supply 56 (corresponding to an "AC drive unit") that uses the commercial power supply 17 as an energy source and passes AC current through a main closed circuit including the shunt resistor 43 and the storage battery 10, and a control unit 74. The AC power supply 56 may be controlled, for example, by either constant current control or constant voltage control. The control unit 74 performs impedance correction processing, similar to FIG. 4 .

[0102] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, a specific example of the battery state calculation device described in the first embodiment will be described using Figures 13 and 14. Figure 13 shows a system including a storage battery 10 and a battery state calculation device 120 attached to the storage battery 10. Figure 14 is a diagram of the configuration shown in Figure 13 with the battery case, circuit board, etc. omitted.

[0103] The battery state calculation device 120 includes a circuit board 90. The circuit board 90 is provided with a limiting resistor 41, a current control switch 42, a shunt resistor 43, a positive voltage path 31, a negative voltage path 32, a positive current path 53, and a negative current path 54. In the circuit board 90, the positive voltage path 31, the negative voltage path 32, the positive current path 53, and the negative current path 54 are configured by wiring patterns, vias, etc.

[0104] The battery state calculation device 120 includes a processing unit 91. The processing unit 91 is configured as an integrated circuit and is provided on a circuit board 90. The processing unit 91 has the functions of the voltage detection unit 33, the current processing unit 50, the reference signal generation unit 60, and the control device 70 including a processor and a storage unit, all of which are described in the first embodiment.

[0105] The storage battery 10 includes a wound body 13, a positive electrode side current collector 14a, a negative electrode side current collector 14b, a positive electrode side conductive member 15a, a negative electrode side conductive member 15b, and a battery case 16. The wound body 13 has a flat rectangular parallelepiped shape. The positive electrode side current collector 14a is provided at a first end in a first direction (width direction) of the wound body 13, and the negative electrode side current collector 14b is provided at a second end in the width direction of the wound body 13. Each of the current collectors 14a, 14b extends in a third direction (height direction) perpendicular to the width direction and the second direction (thickness direction) of the wound body 13.

[0106] A positive electrode conductive member 15a is provided at one end in the height direction of the positive electrode current collector 14a, and a negative electrode conductive member 15b is provided at one end in the height direction of the negative electrode current collector 14b. A positive electrode terminal 10a is provided on the positive electrode conductive member 15a, and a negative electrode terminal 10b is provided on the negative electrode conductive member 15b.

[0107] Conventionally, a complex impedance measurement system has been constructed that focuses on the wiring on the outside of the battery case 16. Here, the core component of the storage battery 10 is the winding 13. The internal structure of the storage battery that draws current from the winding 13 must also be considered as part of the circuit. Therefore, when quantifying the mutual inductance Mv between the main closed circuit and the current detection closed circuit 55 and the mutual inductance Mi between the main closed circuit and the current detection closed circuit 55, it is desirable that the relative position of the circuit board 90 with respect to the internal structure of the storage battery 10, such as the winding 13, is also fixed. Therefore, the circuit board 90 that constitutes the battery state calculation device 120 of this embodiment is firmly fixed to the storage battery 10.

[0108] 14 , the voltage fluctuation measurement path L and the current measurement path C0 will be described when the internal structure of the storage battery 10 is taken into consideration. The voltage fluctuation measurement path L (specifically, the voltage detection closed circuit 34) is a closed circuit including the positive electrode voltage path 31, the positive electrode conductive member 15a, the positive electrode current collector 14a, the wound body 13, the negative electrode current collector 14b, the negative electrode conductive member 15b, the negative electrode voltage path 32, and a processing unit 91. The current measurement path C0 (specifically, the current detection closed circuit 55) is a closed circuit including the shunt resistor 43, the positive electrode current path 53, the processing unit 91, and the negative electrode current path 54.

[0109] The mutual inductance Mv is a mutual inductance resulting from a magnetic field generated on the closed surface formed by the voltage fluctuation measurement path L by the current flowing through the main closed circuit. The mutual inductance Mi is a mutual inductance resulting from a magnetic field generated on the closed surface formed by the current measurement path C0 by the current flowing through the main closed circuit. In the example shown in Fig. 14, the paths of the main closed circuit, the current detection closed circuit 55, and the voltage detection closed circuit 34 partially overlap, but there is a difference in that they are the currents that generate the magnetic field and the measurement of the voltage fluctuations that are the cause and effect of that, and the overlapping parts of the paths are also considered to be the mutual inductance.

[0110] According to the present embodiment described above, it is possible to achieve the same effects as the first embodiment.

[0111] Third Embodiment A third embodiment will now be described with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in FIG. 15 , a battery state calculation device 220 is provided in a vehicle.

[0112] The system mounted on the vehicle includes a battery state calculation device 220, a battery pack 1000, an inverter 130, a rotating electrical machine 140, and a relay SMR. The inverter 130 includes a plurality of phases (three phases) of series-connected upper arm switches SH and lower arm switches SL. An armature winding of the rotating electrical machine 140 is connected to a connection point between the upper arm switches SH and the lower arm switches SL. The rotor of the rotating electrical machine 140 is capable of transmitting power to drive wheels 150 of the vehicle. The inverter 130 and the battery pack 1000 are connected via the relay SMR.

[0113] The battery pack 1000 includes a series connection of multiple storage batteries 100. In this embodiment, for convenience, the battery pack 1000 includes four storage batteries 100: first, second, third, and fourth storage batteries 100A, 100B, 100C, and 100D. Each of the storage batteries 100A, 100B, 100C, and 100D includes a positive terminal 101a and a negative terminal 101b. The storage batteries 100A, 100B, 100C, and 100D have the same specifications, specifically, the same rated voltage and full charge capacity.

[0114] The system includes an inverter control device 131. The inverter control device 131 has a processor and a memory unit. The inverter control device 131 controls the switching of the upper and lower arm switches SH and SL of the inverter 130 to run the vehicle.

[0115] In the battery state calculation device 220, a first end of the limiting resistor 41 is connected to the positive terminal 101a of the first storage battery 100A, which has the highest potential among the storage batteries 100A, 100B, 100C, and 100D. A second end of the shunt resistor 43 is connected to the negative terminal 101b of the fourth storage battery 100D, which has the lowest potential among the storage batteries 100A, 100B, 100C, and 100D. In this embodiment, a closed circuit including the limiting resistor 41, the current control switch 42, the shunt resistor 43, and the battery pack 1000 corresponds to a main closed circuit.

[0116] The battery state calculation device 220 includes a monitoring IC 92. The monitoring IC 92 includes a voltage detection unit 33, a current modulation unit 51, a current detection unit 52, a reference signal generation unit 60, and a control unit 93, which are individually provided corresponding to each of the storage batteries 100A, 100B, 100C, and 100D. The voltage detection unit 33 and the positive terminal 101a are connected by a positive voltage path 31, and the voltage detection unit 33 and the negative terminal 101b are connected by a negative voltage path 32.

[0117] The control unit 93 receives detection values ​​from the voltage detection unit 33, the current detection unit 52, the temperature sensor 80, and the pressure sensor 81. The temperature sensor 80 detects the temperature of each of the storage batteries 100A, 100B, 100C, and 100D. The pressure sensor 81 detects the pressure of each of the storage batteries 100A, 100B, 100C, and 100D.

[0118] The control unit 93 inputs a command to generate a reference signal to the reference signal generation unit 60. The control unit 93, which functions as a "calculation unit," calculates the real and imaginary parts of the complex impedance of each of the storage batteries 100A, 100B, 100C, and 100D based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52. The control unit 93 creates, for example, a complex impedance plane plot (Cole-Cole plot) based on the calculation results, and grasps the state of charge (SOC) and state of health (SOH) of each of the storage batteries 100A, 100B, 100C, and 100D.

[0119] 16 shows an example of a battery state calculation device 220. The positive electrode terminal 101a and the negative electrode terminal 101b of each of the storage batteries 100A, 100B, 100C, and 100D that are adjacent in potential are connected by an intermediate conductive member 103 (e.g., a bus bar). The positive electrode terminal 101a of the first storage battery 100A and the limiting resistor 41 are electrically connected by a first end conductive member 102 (e.g., a bus bar). The negative electrode terminal 101b of the fourth storage battery 100D and the shunt resistor 43 are electrically connected by a second end conductive member 104 (e.g., a bus bar). In this embodiment, the system is configured so that the relative positions of the system components, including the battery state calculation device 220, the inverter 130, the rotating electric machine 140, and the battery pack 1000, are fixed.

[0120] Next, an impedance correction process for reducing the difference in relative error between the complex impedances of the storage batteries 100A, 100B, 100C, and 100D will be described. In this embodiment, the difference in relative error between the complex impedance of one of the storage batteries 100A, 100B, 100C, and 100D as a reference battery and the complex impedance of the remaining target batteries is reduced. In this embodiment, the reference battery is the first storage battery 100A, and the target batteries are the second, third, and fourth storage batteries 100B, 100C, and 100D.

[0121] In this embodiment, the impedance correction process is performed assuming that the true complex impedances Zt of the storage batteries 100A, 100B, 100C, and 100D are the same. For example, when the storage batteries 100A, 100B, 100C, and 100D are brand new, the complex impedances of the storage batteries 100A, 100B, 100C, and 100D are the same. In the following formulas, values ​​related to the first storage battery 100A are given the subscript A, values ​​related to the second storage battery 100B are given the subscript B, values ​​related to the third storage battery 100C are given the subscript C, and values ​​related to the fourth storage battery 100D are given the subscript D.

[0122] Referring to the above equation (eq7), the following equations (eq15) to (eq18) hold for each of the storage batteries 100A, 100B, 100C, and 100D.

[0123]

[0124]

[0125]

[0126] In this embodiment, a common monitoring IC 92 is provided with a voltage detection unit 33, a current detection unit 52, and a reference signal generation unit 60. Therefore, it is assumed that "ΔβA, ΔβB, ΔβC, ΔβD = 0" and "ΔγA, ΔγB, ΔγC, ΔγD = 0." Therefore, the following equations (eq19) to (eq21) are derived.

[0127]

[0128]

[0129] The currents of the storage batteries 100A, 100B, 100C, and 100D are detected by a common current detection unit 52. Therefore, in the above equations (eq19) to (eq21), θpA, θpB, θpC, and θpD have the same values, and MiA / RsA, MiB / RsB, MiC / RsC, and MiD / RsD have the same values.

[0130] In the above equations (eq19) to (eq21), the amplitude influence coefficients KampA, KampB, KampC, and KampD and the phase influence coefficients KphA, KphB, KphC, and KphD are coefficients determined by the battery state calculation device 220.

[0131] In the above equation (eq19), ZmA and ZmB are complex impedances calculated based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52 corresponding to the first and second storage batteries 100A and 100B. In the above equation (eq20), ZmC is a complex impedance calculated based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52 corresponding to the third storage battery 100C. In the above equation (eq21), ZmD is a complex impedance calculated based on the detection values ​​of the voltage detection unit 33 and the current detection unit 52 corresponding to the fourth storage battery 100D.

[0132] Referring to the above equation (eq19), the difference between "ZmB x KampB x KphB" and "ZmA x KampA x KphA" is the error in the complex impedance of the first and second storage batteries 100A and 100B. Referring to the above equation (eq20), the difference between "ZmC x KampC x KphC" and "ZmA x KampA x KphA" is the error in the complex impedance of the first and third storage batteries 100A and 100C. Referring to the above equation (eq21), the difference between "ZmD x KampD x KphD" and "ZmA x KampA x KphA" is the error in the complex impedance of the first and fourth storage batteries 100A and 100D.

[0133] Therefore, by removing the influence of "ZmA×KampA×KphA" from "ZmB×KampB×KphB", "ZmC×KampC×KphC" and "ZmD×KampD×KphD", the relative error of the complex impedances of the four storage batteries can be reduced.

[0134] FIG. 17 is a flowchart of the impedance correction process executed by the control unit 93.

[0135] In step S20, it is determined whether the vehicle is stopped. If it is determined that the vehicle is stopped, execution of the processes from step S21 onward is permitted. This reduces the effect of vibrations that occur as the vehicle travels on the relative positions of the components of the battery state calculation device 220. As a result, it is possible to improve the calculation accuracy of correction values ​​that reduce the relative errors in the complex impedances of the storage batteries 100A, 100B, 100C, and 100D.

[0136] If it is determined in step S20 that the vehicle is stopped, the process proceeds to step S21, where it is determined whether a temperature condition is met. The temperature condition is that the temperatures of the storage batteries 100A, 100B, 100C, and 100D detected by the temperature sensor 80 are the same or equivalent. The temperatures of the storage batteries 100A, 100B, 100C, and 100D are equivalent if the absolute value of the difference ΔT between the highest and lowest temperatures of the storage batteries 100A, 100B, 100C, and 100D is, for example, 5°C or less, 3°C or less, 1°C or less, or 0.5°C or less.

[0137] If it is determined that the temperature condition is met, the process proceeds to step S22, where it is determined whether the voltage condition is met. The voltage condition is that the inter-terminal voltages of the storage batteries 100A, 100B, 100C, and 100D detected by the voltage detection unit 33 are the same or equivalent when no current flows through the storage batteries 100A, 100B, 100C, and 100D. The inter-terminal voltages of the storage batteries 100A, 100B, 100C, and 100D are equivalent, for example, if "|ΔV| / Vstd×100≦0.3%," "|ΔV| / Vstd×100≦0.1%, or "|ΔV| / Vstd×100≦0.03%." ΔV is the absolute value of the difference ΔV between the highest and lowest inter-terminal voltages of the storage batteries 100A, 100B, 100C, and 100D. Vstd is the rated voltage of each of the storage batteries 100A, 100B, 100C, and 100D.

[0138] In addition, the voltage condition may be the SOC of each of the storage batteries 100A, 100B, 100C, and 100D instead of the detected voltage. Furthermore, in addition to the temperature and voltage conditions, a pressure condition of each of the storage batteries 100A, 100B, 100C, and 100D may be added. The pressure condition is a condition that the pressures of each of the storage batteries 100A, 100B, 100C, and 100D detected by the pressure sensor 81 are the same or equivalent.

[0139] If it is determined in step S22 that the voltage condition is met, the process proceeds to step S23, where a reference signal generation command is input to the reference signal generator 60 so that the current modulator 51 controls the current control switch 42. Here, a frequency sweep is performed to gradually change (increase or decrease) the angular frequency ω0 of the reference signal. As a result, an AC current fluctuating at the frequency ω0 of the reference signal flows through each of the storage batteries 100A, 100B, 100C, and 100D. While the AC current is flowing, the current detector 52 acquires the detected current Im, and the voltage detector 33 acquires the detected voltages VmA, VmB, VmC, and VmD ​​corresponding to each of the storage batteries 100A, 100B, 100C, and 100D. Specifically, the detected current Im and the detected voltages VmA, VmB, VmC, and VmD ​​corresponding to the angular frequency are acquired.

[0140] In step S24, the complex impedances ZmA (= VmA / Im), ZmB (= VmB / Im), ZmC (= VmC / Im), and ZmD (= VmD / Im) of each storage battery 100A, 100B, 100C, and 100D are calculated based on the acquired detected current Im and detected voltages VmA, VmB, VmC, and VmD.

[0141] Then, the calculated complex impedance ZmA of the first storage battery 100A is multiplied by the amplitude influence coefficient KampA and the phase influence coefficient KphA to calculate "ZA = ZmA × KampA × KphA." The calculated complex impedance ZmB of the second storage battery 100B is multiplied by the amplitude influence coefficient KampB and the phase influence coefficient KphB to calculate "ZB = ZmB × KampB × KphB." The calculated complex impedance ZmC of the third storage battery 100C is multiplied by the amplitude influence coefficient KampC and the phase influence coefficient KphC to calculate "ZC = ZmC × KampC × KphC." The calculated complex impedance ZmD of the fourth storage battery 100D is multiplied by the amplitude influence coefficient KampD and the phase influence coefficient KphD to calculate "ZD = ZmD × KampD × KphD."

[0142] The amplitude influence coefficients KampA, KampB, KampC, and KampD and the phase influence coefficients KphA, KphB, KphC, and KphD are values ​​calculated in advance by, for example, experiments or calculations, and are stored in a storage unit of the control unit 93. The control unit 93 reads out from the storage unit the amplitude influence coefficients and phase influence coefficients used in calculating ZA to ZD.

[0143] In step S25, as shown in the following equation (eq22), ZA is subtracted from ZB calculated in step S24 to calculate a correction value ΔZkB.

[0144] In step S25, as shown in the following equation (eq23), ZA is subtracted from ZC calculated in step S24 to calculate a correction value ΔZkC.

[0145] In step S25, as shown in the following equation (eq24), ZA is subtracted from ZD calculated in step S24 to calculate a correction value ΔZkD.

[0146] The correction values ​​ΔZkB, ΔZkC, and ΔZkD are values ​​for correcting the imaginary part of the complex impedance. The correction values ​​ΔZkB, ΔZkC, and ΔZkD become larger as the angular frequency ω0 becomes higher.

[0147] In step S26, ZB, ZC, and ZD calculated in step S24 are corrected based on the calculated correction values ​​ΔZkB, ΔZkC, and ΔZkD. Specifically, as shown in the following equation (eq25), the correction value ΔZkB is subtracted from ZB to calculate the corrected impedance ZcB of the second storage battery 100B.

[0148] Furthermore, as shown in the following equation (eq26), the correction value ΔZkC is subtracted from ZC to calculate the corrected impedance ZcC of the third storage battery 100C.

[0149] Furthermore, as shown in the following equation (eq27), the correction value ΔZkD is subtracted from ZD to calculate the corrected impedance ZcD of the fourth storage battery 100D.

[0150] In step S27, the calculated correction values ​​ΔZkB, ΔZkC, and ΔZkD are associated with the angular frequency ω0 and stored in the storage unit. Note that the information stored in the storage unit may be table information or formula information in which the frequency ω0 and the correction values ​​ΔZkB, ΔZkC, and ΔZkD are associated. If the formula information is used, the formula may be, for example, a polynomial, an exponential function, a trigonometric function, or a combination of these functions.

[0151] According to the present embodiment described above, the relative error of the complex impedances of the second, third, and fourth storage batteries 100B, 100C, and 100D relative to the complex impedance of the first storage battery 100A can be reduced, and the difference in error contained in the complex impedances of each storage battery 100A, 100B, 100C, and 100D can be reduced.

[0152] <Modification of the Third Embodiment> The control unit 93 may execute the impedance correction process shown in steps S21 to S26 in FIG. 17 when it determines that the information on the correction value stored in the storage unit has been lost.

[0153] The control unit 93 may execute the impedance correction process shown in steps S21 to S26 when the vehicle is stored at a vehicle dealer.

[0154] The control unit 93 may perform the impedance correction process on the condition that it determines that the usage period of each of the storage batteries 100A, 100B, 100C, and 100D is equal to or shorter than a predetermined period. If the usage period of each of the storage batteries 100A, 100B, 100C, and 100D is not excessively long, the variation in the true complex impedance Zt of each of the storage batteries 100A, 100B, 100C, and 100D is considered to be small even if each of the storage batteries 100A, 100B, 100C, and 100D is in a used state.

[0155] 17 may be executed before the battery pack 1000 is mounted on a vehicle. For example, the process may be executed during the manufacturing process of the battery pack 1000 in a factory.

[0156] 18 and 19, the system may include a module 300 that integrates a series connection of multiple storage batteries 100A to 100D and a monitoring IC 92. In this case, the voltage detection unit 33, the current processing unit 50, and the reference signal generation unit 60 are arranged at a predetermined distance apart, so the phase differences Δα, Δβ, and Δγ may not be zero.

[0157] 20 , a shunt resistor 143 may be provided between the fourth storage battery 100D and the relay SMR. In this case, the main closed circuit is a closed circuit including each of the storage batteries 100A to 100D, the relay SMR, the upper arm switch SH, the armature winding of the rotating electric machine 140, the lower arm switch SL, the relay SMR, and the shunt resistor 43, as illustrated by the dashed arrows. In addition, in the impedance correction process, the control of flowing AC current to each of the storage batteries 100A to 100D is the switching control of the inverter 130 by the inverter control device 131. In this case, the inverter 130 and the inverter control device 131 correspond to the "AC drive unit."

[0158] As shown in FIG. 21 , a current detection IC 94 may be provided in the battery state calculation device 220 in addition to a voltage detection IC (monitoring IC 92 ).

[0159] The system mounted on the vehicle includes a changeover switch SMC and a charger 132 including a DC-DC converter. The charger 132 is connected to the series-connected battery array 100A to 100D via the changeover switch SMC. In this embodiment, for convenience, the charger 132 and the changeover switch SMC are controlled by an inverter control device 131.

[0160] The inverter control device 131 performs switching control of the upper and lower arm switches SH, SL of the inverter 130 to rotate the rotor of the rotating electric machine 140 and run the vehicle. In this case, the inverter control device 131 sets a first state in which the relay SMR is turned on and the changeover switch SMC is turned off. On the other hand, the inverter control device 131 controls the charger 132 to perform external charging in which the series-connected array of storage batteries 100A to 100D is charged from an external power source 133 via the charger 132. In this case, the inverter control device 131 sets a second state in which the changeover switch SMC is turned on and the relay SMR is turned off.

[0161] The control unit 93 cooperates with the inverter control device 131 to perform the impedance correction process shown in FIG. 17 in each of the first and second states. This allows for calculation of correction values ​​corresponding to each of the first and second states. By controlling the relay SMR and the selector switch SMC in this manner, the correction value can be accurately calculated in the first state without being affected by the impedance in the external power supply. Furthermore, in the second state, the correction value can be calculated without being affected by the impedance of a smoothing capacitor or the like in the inverter 130.

[0162] An example of the arrangement of an electrical path 45 connecting the positive terminal of the battery with the highest potential and the negative terminal of the battery with the lowest potential among a plurality of storage batteries connected in series will be described. The electrical path 45 includes a limiting resistor 41, a current control switch 42, and a shunt resistor 43.

[0163] Fig. 22 shows an example of six storage batteries 100A to 100F. The calculation results of the mutual inductance Mv of each of the storage batteries 100A to 100F in this case are shown in Fig. 23. Fig. 24 shows an arrangement of the electrical path 45 that is different from that shown in Fig. 22. The calculation results of the mutual inductance Mv of each of the storage batteries 100A to 100F in this case are shown in Fig. 25. Because the mutual inductance Mv differs for each of the storage batteries 100A to 100F, it is desirable to calculate a correction value corresponding to the target battery among each of the storage batteries 100A to 100F.

[0164] Note that, depending on the relative positions of the multiple storage batteries and the battery state calculation device, the calculation results shown in FIG. 26 may be obtained. In FIG. 26, among the multiple storage batteries connected in series, the mutual inductance Mv of the highest and lowest storage batteries 100A, 100E is the same or equivalent, and the mutual inductance Mv of the storage batteries 100B, 100D adjacent to the highest and lowest storage batteries 100A, 100E is the same or equivalent. In this case, the correction values ​​calculated for some of the four target batteries constituting the multiple storage batteries 100A-100E can be used to correct the complex impedances of the other target batteries. This reduces the computational load on the battery state calculation device.

[0165] Fourth Embodiment The fourth embodiment will be described below with reference to the drawings, focusing on differences from the third embodiment. In this embodiment, the relative error of the complex impedance of an on-board storage battery relative to the complex impedance of a reference battery calculated by a battery state calculation device (hereinafter referred to as an external calculation device) external to the vehicle, such as in a laboratory of a research institute, is reduced. The external calculation device is, for example, the first battery state calculation device 20A of the first embodiment, and corresponds to the "first battery state calculation device."

[0166] The complex impedance of a battery pack having the same specifications as the battery pack 1000 installed in the vehicle is calculated by an external calculation device. In this case, it is assumed that the complex impedance ZmS of one reference battery (e.g., the first battery) of the four storage batteries constituting the battery pack is calculated by the external calculation device based on the detection values ​​of the current detection unit 52 and the voltage detection unit 33. The true impedance Zs of the reference battery is expressed by the following equation (eq28):

[0167] On the other hand, the relationship between the complex impedances of the first, second, third, and fourth storage batteries 100A, 100B, 100C, and 100D calculated by the battery state calculation device 220 (corresponding to the "second battery state calculation device") provided in the vehicle and the true impedances is expressed by the following equations (eq29) to (eq32).

[0168]

[0169]

[0170]

[0171] It is assumed that the true impedances ZA, ZB, ZC, and ZD of the first, second, third, and fourth storage batteries 100A, 100B, 100C, and 100D installed in the vehicle are the same as the true impedance Zs of the reference battery (first storage battery) that is the measurement target of the external calculation device. In this case, based on the above equations (eq28) to (eq32), the correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD of the first, second, third, and fourth storage batteries 100A, 100B, 100C, and 100D are determined by the following equations (eq33) to (eq36).

[0172]

[0173]

[0174]

[0175] The correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD are calculated in advance based on the calculation results of the complex impedance in an external calculation device, for example, during design of the battery state calculation device 22. The calculated correction values ​​ZkA, ΔZkB, ΔZkC, and ΔZkD are stored in the memory of the control unit 93.

[0176] FIG. 27 is a flowchart of the impedance correction process executed by the control unit 93.

[0177] In step S30, similar to step S20, it is determined whether the vehicle is stopped.

[0178] If it is determined in step S30 that the vehicle is stopped, the process proceeds to step S31, where it is determined whether or not the temperature condition is met, similarly to step S21.

[0179] If it is determined that the temperature condition is met, the process proceeds to step S32, where it is determined whether or not the voltage condition is met, similarly to step S22.

[0180] If it is determined in step S32 that the voltage condition is met, the process proceeds to step S33, where, similar to step S23, a command to generate a reference signal is input to the reference signal generator 60 so that the current modulator 51 controls the current control switch 42. While AC current is flowing through each of the storage batteries 100A, 100B, 100C, and 100D, the current detector 52 obtains the detected current Im, and the voltage detector 33 obtains the detected voltages VmA, VmB, VmC, and VmD ​​corresponding to each of the storage batteries 100A, 100B, 100C, and 100D. Specifically, the detected current Im and the detected voltages VmA, VmB, VmC, and VmD ​​corresponding to the angular frequency are obtained.

[0181] In step S34, similar to step S24, the complex impedances ZmA (= VmA / Im), ZmB (= VmB / Im), ZmC (= VmC / Im), and ZmD (= VmD / Im) of each storage battery 100A, 100B, 100C, and 100D are calculated based on the acquired detected current Im and detected voltages VmA, VmB, VmC, and VmD.

[0182] Then, the calculated complex impedance ZmA of the first storage battery 100A is multiplied by the amplitude influence coefficient KampA and the phase influence coefficient KphA to calculate "ZA = ZmA × KampA × KphA." The calculated complex impedance ZmB of the second storage battery 100B is multiplied by the amplitude influence coefficient KampB and the phase influence coefficient KphB to calculate "ZB = ZmB × KampB × KphB." The calculated complex impedance ZmC of the third storage battery 100C is multiplied by the amplitude influence coefficient KampC and the phase influence coefficient KphC to calculate "ZC = ZmC × KampC × KphC." The calculated complex impedance ZmD of the fourth storage battery 100D is multiplied by the amplitude influence coefficient KampD and the phase influence coefficient KphD to calculate "ZD = ZmD × KampD × KphD."

[0183] The amplitude influence coefficients KampA, KampB, KampC, and KampD and the phase influence coefficients KphA, KphB, KphC, and KphD are values ​​calculated in advance by, for example, experiments or calculations, and are stored in a storage unit of the control unit 93. The control unit 93 reads out the amplitude influence coefficients and phase influence coefficients used to calculate ZA to ZD from the storage unit.

[0184] In step S35, the correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD of the above equations (eq33) to (eq36) are read from the storage unit. The correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD are values ​​for correcting the imaginary part of the complex impedance. The correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD become larger as the angular frequency ω0 increases.

[0185] In step S36, ZA, ZB, ZC, and ZD calculated in step S34 are corrected based on the read correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD. Specifically, the correction values ​​ΔZkA, ΔZkB, ΔZkC, and ΔZkD are subtracted from ZA, ZB, ZC, and ZD to calculate the corrected impedances ZcA, ZcB, ZcC, and ZcD of the first, second, third, and fourth storage batteries 100A, 100B, 100C, and 100D.

[0186] In step S37, the calculated correction impedances ZcA, ZcB, ZcC, and ZcD are associated with the angular frequency ω0 and stored in the storage unit.

[0187] According to the present embodiment described above, it is possible to reduce the variation in the relative error of the complex impedance of the vehicle-mounted storage battery using the complex impedance of the reference battery calculated outside the vehicle as a reference.

[0188] Other Embodiments The above-described embodiments may be modified as follows.

[0189] In the third and fourth embodiments, when a magnetic field caused by a current flowing through the inverter 130 or the like intersects with the voltage detection closed circuit 34 and the current detection closed circuit 55, an induced electromotive force may be generated, which may become noise. The system is provided with a fixing mechanism that fixes the relative position of the system including the inverter 130 and each closed circuit 34, 55. Here, the angular frequency ω0 of the reference signal may be set to a frequency that is shifted by a predetermined frequency (for example, several Hz) from the natural frequency of the system.

[0190] When multiple natural frequencies exist, instead of shifting one of the natural frequencies, a value shifted from each of the multiple natural frequencies may be selected as the angular frequency ω0 of the reference signal. The amount of shift of the angular frequency ω0 from the natural frequency may be, for example, a value that does not pass through the bandpass filter of the impedance measurement circuit. For example, if the bandpass filter width is 10 Hz, the shift amount is preferably 10 Hz or more. The impedance value of a storage battery generally changes smoothly with frequency. Even if the measurement frequency (angular frequency ω0) is shifted to avoid the desired angular frequency ω0 from coinciding with the natural frequency, this method of shifting the measurement frequency is viable because it has little impact on battery control. If shifting the measurement frequency is difficult, the natural frequency of the system may be shifted. For example, the natural frequency of the system can be shifted by changing the spacing between the points held down by the fixing mechanism or by changing the shape or weight of the components. The correction value is preferably calculated when no vibration is occurring or when selecting an angular frequency ω0 that avoids the natural vibration.

[0191] As the battery capacity increases, the value of the imaginary part of the battery's complex impedance decreases. In the case of a battery with a large battery capacity (e.g., a 100 Ah-class battery), the imaginary part of the complex impedance is, for example, on the order of 10 μΩ. On the other hand, the amount of change in the imaginary part due to the natural vibration is, for example, about 2.5 μΩ. In this case, this amount of change cannot be ignored. Therefore, measures to shift the vibration frequency are effective.

[0192] For example, in the third and fourth embodiments, the battery state calculation device may calculate an individual correction value for each storage battery to be corrected based on the length L of the positive voltage path 31 and the negative voltage path 32 of each voltage detection circuit and the cross-sectional area A of the positive voltage path 31 and the negative voltage path 32.

[0193] Taking the above equation (eq15) as an example, when the influence of the length L and the cross-sectional area A is taken into consideration, a coefficient Gt is added as shown in the following equation (eq37).

[0194] The longer the length L of the positive voltage path 31 and the negative voltage path 32, the greater the resistance of the positive voltage path 31 and the negative voltage path 32. As a result, the amount of voltage drop that occurs in the positive voltage path 31 and the negative voltage path 32 also increases, and the difference between the detected voltage and the actual voltage increases. In light of this, as shown in FIG. 23 , the battery state calculation device may set the coefficient Gt to be smaller as the length L increases.

[0195] The smaller the cross-sectional areas of the positive voltage path 31 and the negative voltage path 32, the larger the resistance values ​​of the positive voltage path 31 and the negative voltage path 32. In consideration of this, as shown in Fig. 28 , the battery state calculation device may set the coefficient Gt to be smaller as the cross-sectional area A is smaller.

[0196] Considering the influence of the angular frequency ω0 of the reference signal, a coefficient St is added as shown in the above equation (eq37). When calculating the complex impedance, a frequency sweep is performed for each frequency ω0. The influence of the skin effect differs depending on whether the angular frequency ω0 is high or low. The higher the frequency, the greater the resistance value. In light of this, the battery state calculation device may set the coefficient St to be smaller as the angular frequency ω0 increases, as shown in FIG. 29. The coefficients Gt and St can be calculated in advance, for example.

[0197] The increase in wiring resistance due to the skin effect can be reduced by increasing the surface area of ​​the metal body that forms the wiring. Therefore, the increase in resistance can be reduced by using multi-core wires as harnesses. However, in recent years, in FPC boards used for wiring in battery modules and the like, each wire has a configuration equivalent to that of a single-core wire. Therefore, it is preferable to correct for the skin effect, especially for modules and packs where the wiring distance is long.

[0198] Furthermore, although the FPC wiring is a pattern wiring equivalent to a single wire, in order to increase the surface area, it is also possible to use a method such as using two or more wires of the same potential or using a wiring pattern with a mesh structure.

[0199] In addition, the following configurations (1) and (2) may be adopted.

[0200] (1) Depending on the distance between the location of the battery cells that make up the battery pack to be measured and the measurement IC that measures the current and voltage of the battery cells, the number of wires with the same potential should be increased in more distant locations, and the number of wires in closer locations should be single wires or fewer than in more distant locations.

[0201] (2) Locations at different distances from the measurement IC are configured with a single wire, while locations farther away are configured with multiple wires. Closer locations require wiring for many battery cells, which requires less space, but farther away locations have fewer unwired battery cells, making it easier to secure space for multiple wires. This has the effect of reducing the skin effect on battery cells farther away while minimizing the increase in FPC board area.

[0202] 30, the voltage detection unit 33 and the current detection unit 52 include a filter circuit 400 to which the acquired voltage difference is input, and an AD converter 401 to which the output value of the filter circuit 400 is input. The output value of the AD converter 401 becomes the voltage and current detection values.

[0203] Here, the gain frequency characteristic and phase frequency characteristic of the filter circuit 400 change depending on the time constant of the filter circuit 400. Here, the amount of change in the gain frequency characteristic in the filter circuit 400 included in the voltage detection unit 33 is set to Gv(ω0), and the amount of change in the gain frequency characteristic in the filter circuit 400 included in the current detection unit 52 is set to Gi(ω0). In this case, using the above equation (eq15) as an example, the following equation (eq38) can be derived by taking the influence of the amount of change into consideration.

[0204] In consideration of this, for example, in the third and fourth embodiments, the battery state calculation device may calculate an individual correction value for each storage battery to be corrected based on the frequency characteristics of the filter circuit 400. Note that the coefficients Gi and Gv can be calculated in advance, for example.

[0205] In the third and fourth embodiments, the impedance correction process may be performed by a server external to the vehicle (e.g., a cloud server) instead of by a control unit provided in the vehicle. In this case, the server may collect correction values ​​corresponding to a large number of vehicles and store the collected correction values ​​in a storage unit of the server. The server may transmit, for example, a statistical value (e.g., an average value) of the collected correction values ​​as a correction value to the control unit of each vehicle.

[0206] As shown in FIG. 31 , in an electrical path that connects the positive and negative terminals of the storage battery and includes a current control switch 42 and a shunt resistor 43, a first fold portion 46 a through which current flows in the opposite direction to the current flow direction of the shunt resistor 43, and a second fold portion 46 b through which current flows in the opposite direction to the current flow direction of the first fold portion 46 a may be provided.

[0207] The magnetic field generated by the current flowing through the first folding portion 46a serves to reduce the magnetic field that links the current detection closed circuit 55 due to the current flowing through the shunt resistor 43. The second folding portion 46b is intended to return the current path changed by the first folding portion 46a to the original path as much as possible. The second folding portion 46b is disposed farther from the current detection closed circuit 55 than the first folding portion 46a. Therefore, the magnetic field that links the current detection closed circuit 55 due to the current flowing through the second folding portion 46b is small, and the influence of the linkage magnetic field on the current detection error is small.

[0208] In the second embodiment, as shown in Fig. 32 , a first fold line 47 corresponding to the first fold line 46 shown in Fig. 31 may be provided on a second plate surface of the circuit board 90, which is the opposite side of the first plate surface on which the shunt resistor 43 is provided. Since no electronic component is interposed between the shunt resistor 43 and the first fold line 47, the potential difference between the shunt resistor 43 and the first fold line 47 can be reduced, making it less likely for insulation breakdown to occur. Note that the first fold line 47 may be provided on the electrical path on the positive terminal 10a side of the storage battery 10, rather than on the electrical path on the negative terminal 10b side of the storage battery 10.

[0209] Various types of storage batteries may be used in the vehicle. For example, a blade cell having a long plate shape may be used as the storage battery.

[0210] The storage battery may also be configured such that a plurality of unit batteries (for example, battery cells) are grouped into battery blocks, and the battery blocks are connected in series.

[0211] Furthermore, the storage battery may have a so-called CTP (Cell to Pack) configuration in which a series connection of multiple battery cells is housed in a housing portion of the chassis of the vehicle, without creating a battery block.

[0212] Furthermore, instead of the CTP configuration, a so-called CTC (Cell to Chassis) configuration may be used in which a housing section for housing a battery cell is configured on the chassis of the vehicle, and multiple battery cells are housed in the housing section.

[0213] The storage battery is not limited to a secondary battery, and may be, for example, a fuel cell.

[0214] The mobile body on which the battery state calculation device is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship.Furthermore, the battery state calculation device is not limited to a mobile body, but may be a stationary device.

[0215] The present disclosure can also be applied to replaceable batteries mounted on mobile objects such as vehicles. In this case, the measurement system may be different when measuring the impedance of a replaceable battery mounted on a mobile object and when measuring the impedance of a replaceable battery removed from the mobile object. For example, when the battery is removed from the mobile object, the impedance of the battery may be measured using a power source not mounted on the mobile object as a signal source. However, the configuration itself, including the measurement signal source, current detection unit, and voltage detection unit, is the same when the battery is mounted on the mobile object and when it is removed from the mobile object, so the correction method of the present disclosure can be used. Using this correction method makes it possible to compare the impedance of a battery mounted on a mobile object and when it is removed from the mobile object.

[0216] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0217] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

A battery state calculation device (20, 120, 220) applied to a system including an electrical path (41-43, SMR, 130, 140) electrically connecting a positive terminal of a storage battery (10, 1000) and a negative terminal of the storage battery, an AC driving unit (42, 51, 56, 60, 130, 131) that passes an AC current through a closed circuit including the electrical path and the storage battery; a voltage detection circuit (31 to 33) connected in parallel to the storage battery and detecting a voltage between the terminals of the storage battery; a current detection circuit (43, 52 to 54) for detecting a current flowing through the closed circuit; A calculation unit (70, 93); Equipped with The calculation unit acquiring a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit, and calculating a complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; calculating correction values ​​(ΔZkA, ΔZkB, ΔZkC, ΔZkD) for correcting a relative error of the calculated complex impedance of the storage battery with respect to the complex impedance of the reference battery, based on the complex impedance of a reference battery to be compared with the calculated complex impedance of the storage battery, and the calculated complex impedance of the storage battery; The battery state calculation device corrects the calculated complex impedance of the storage battery based on the calculated correction value. 　 The storage battery is a series connection of a plurality of unit batteries (100A to 100D), the voltage detection circuit is provided individually corresponding to each of the unit batteries, When one of the unit batteries is the reference battery (100A) and the rest are target batteries (100B to 100D), The calculation unit (93) acquiring detection values ​​of the voltage detection circuits and detection values ​​of the current detection circuits when an AC current is caused to flow through the closed circuit by the AC drive unit, and calculating a complex impedance of each of the unit batteries based on the acquired detection values ​​of the voltage detection circuits and detection values ​​of the current detection circuits; calculating the correction values ​​(ΔZkB, ΔZkC, ΔZkD) for correcting a relative error of the calculated complex impedance of the target battery relative to the calculated complex impedance of the reference battery based on the calculated complex impedance of each unit battery; The battery state calculation device according to claim 1 , wherein the calculated complex impedance of the target battery is corrected based on the calculated correction value. 　 the battery state calculation device is configured so that relative positions of the unit batteries, the electrical paths, the voltage detection circuits, and the current detection circuits are fixed; 3. The battery state calculation device according to claim 2, wherein the calculation unit acquires the detection values ​​of the voltage detection circuits and the detection values ​​of the current detection circuit when an AC current is flowing through the closed circuit with the relative position fixed.

4. The battery state calculation device according to claim 3, wherein the calculation unit calculates the correction value according to a difference between a mutual inductance between the voltage detection circuit that detects the inter-terminal voltage of the reference battery and the closed circuit, and a mutual inductance between the voltage detection circuit that detects the inter-terminal voltage of the target battery and the closed circuit. 　 The battery state calculation device according to claim 4 , wherein the calculation unit calculates the correction value to be larger as the frequency (ω0) of the AC current supplied by the AC drive unit increases. 　 the storage battery is a series connection of three or more of the unit batteries, 6. The battery state calculation device according to claim 2, wherein the calculation unit calculates the correction value for each of the target batteries individually. 　 The system is mounted on a vehicle, The battery state calculation device according to any one of claims 2 to 5, wherein the calculation unit acquires the detection values ​​of the voltage detection circuits and the detection values ​​of the current detection circuit when AC current is flowing through the closed circuit, on the condition that it is determined that the vehicle is stopped. 　 Each of the voltage detection circuits is a positive electrode side voltage path (31) electrically connected to the positive electrode terminal of the unit battery; a negative electrode side voltage path (32) electrically connected to the negative electrode terminal of the unit battery; a voltage difference between the positive electrode side voltage path and the negative electrode side voltage path is detected as a terminal voltage of the unit battery; The battery state calculation device according to claim 6 , wherein the calculation unit calculates the correction value for each of the target batteries based on the lengths of the positive voltage path and the negative voltage path of each of the voltage detection circuits. 　 Each of the voltage detection circuits is a positive electrode side voltage path (31) electrically connected to the positive electrode terminal of the unit battery; a negative electrode side voltage path (32) electrically connected to the negative electrode terminal of the unit battery; a filter circuit (400) to which a voltage difference between the positive voltage path and the negative voltage path is input; detecting a terminal voltage of the unit battery based on an output value of the filter circuit; The current detection circuit a shunt resistor (43) provided in the electrical path; a current path (53, 54) connected to both ends of the shunt resistor; a filter circuit (400) to which a voltage difference between the current paths connected to both ends is input; a current flowing through the closed circuit is detected based on an output value of the filter circuit; The battery state calculation device according to claim 6 , wherein the calculation unit calculates the correction value for each of the target batteries based on frequency characteristics of the filter circuits of the voltage detection circuit and the current detection circuit. 　 the battery state calculation device includes a first battery state calculation device (20A) and a second battery state calculation device (220) provided at a location different from the first battery state calculation device, the first battery state calculation device, a positive electrode connection portion (40a) to which a positive electrode terminal of the storage battery is connected; a negative electrode connection portion (40b) to which the negative electrode terminal of the storage battery is connected; the electrical path connecting the positive electrode connecting portion and the negative electrode connecting portion; Equipped with In the first battery state calculation device, the calculation unit acquires detection values ​​of the voltage detection circuit and the current detection circuit when an AC current is caused to flow through the closed circuit by the AC drive unit, with the reference battery having the same specifications as the storage battery connected to the positive electrode connection portion and the negative electrode connection portion, and with the relative positions of the reference battery, the positive electrode connection portion, the negative electrode connection portion, the electrical path, the voltage detection circuit, and the current detection circuit fixed, and calculates a complex impedance of the reference battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; In the second battery state calculation device, the calculation unit acquires a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit, and calculates a complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; 2. The battery state calculation device according to claim 1, wherein the correction value is calculated based on the calculated complex impedance of the storage battery and the complex impedance of the reference battery calculated by the first battery state calculation device, to correct a relative error of the calculated complex impedance of the storage battery with respect to the calculated complex impedance of the reference battery. 　 the battery state calculation device includes a first battery state calculation device (20A) and a second battery state calculation device (20B) provided at a location different from the first battery state calculation device, the first battery state calculation device and the second battery state calculation device, a positive electrode connection portion (40a) to which a positive electrode terminal (10a) of the storage battery (10) is connected; a negative electrode connection portion (40b) to which a negative electrode terminal (10b) of the storage battery is connected; The electrical path (41 to 43) connecting the positive electrode connection part and the negative electrode connection part; Equipped with In the first battery state calculation device, the calculation unit acquires a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is caused to flow through the closed circuit by the AC drive unit in a state in which the storage battery is connected to the positive electrode connection portion and the negative electrode connection portion and the relative positions of the storage battery, the positive electrode connection portion, the negative electrode connection portion, the electrical path, the voltage detection circuit, and the current detection circuit are fixed, and calculates a complex impedance of the storage battery based on the acquired detection value of the voltage detection circuit and the detection value of the current detection circuit; In the second battery state calculation device, the calculation unit acquires a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is caused to flow through the closed circuit by the AC drive unit, in a state in which the storage battery, whose complex impedance is calculated in the first battery state calculation device, is connected to the positive electrode connection portion and the negative electrode connection portion, and relative positions of the storage battery, the positive electrode connection portion, the negative electrode connection portion, the electrical path, the voltage detection circuit, and the current detection circuit are fixed, and calculates a complex impedance of the storage battery based on the acquired detection value of the voltage detection circuit and the detection value of the current detection circuit; 2. The battery state calculation device according to claim 1, wherein the storage battery in a state connected to the positive electrode connection portion and the negative electrode connection portion of the first battery state calculation device is the reference battery (10), and the storage battery in a state connected to the positive electrode connection portion and the negative electrode connection portion of the second battery state calculation device is the target battery (10), and the calculation unit of at least one of the first battery state calculation device and the second battery state calculation device calculates the correction value that corrects a relative error of the calculated complex impedance of the target battery with respect to the calculated complex impedance of the reference battery, based on the complex impedance of the reference battery calculated in the first battery state calculation device and the complex impedance of the target battery calculated in the second battery state calculation device. 　 an electrical path (41-43, SMR, 130, 140) electrically connecting a positive terminal of the storage battery (10, 1000) and a negative terminal of the storage battery; an AC driving unit (42, 51, 56, 60, 130, 131) that passes an AC current through a closed circuit including the electrical path and the storage battery; a voltage detection circuit (31 to 33) connected in parallel to the storage battery and detecting a voltage between the terminals of the storage battery; a current detection circuit (43, 52 to 54) for detecting a current flowing through the closed circuit; In a program applied to a system comprising: The processor (71, 93) a process of acquiring a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit; A process of calculating a complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; calculating correction values ​​(ΔZkA, ΔZkB, ΔZkC, ΔZkD) for correcting a relative error of the calculated complex impedance of the storage battery relative to the complex impedance of the reference battery, based on the complex impedance of a reference battery to be compared with the calculated complex impedance of the storage battery and the calculated complex impedance of the storage battery; a process of correcting the calculated complex impedance of the storage battery based on the calculated correction value; A program that executes. 　 an electrical path (41-43, SMR, 130, 140) electrically connecting a positive terminal of the storage battery (10, 1000) and a negative terminal of the storage battery; an AC driving unit (42, 51, 56, 60, 130, 131) that passes an AC current through a closed circuit including the electrical path and the storage battery; a voltage detection circuit (31 to 33) connected in parallel to the storage battery and detecting a voltage between the terminals of the storage battery; a current detection circuit (43, 52 to 54) for detecting a current flowing through the closed circuit; A control method for a battery control device (20, 120, 220) comprising: acquiring a detection value of the voltage detection circuit and a detection value of the current detection circuit when an AC current is flowing through the closed circuit by the AC drive unit; calculating a complex impedance of the storage battery based on the acquired detection values ​​of the voltage detection circuit and the current detection circuit; calculating correction values ​​(ΔZkA, ΔZkB, ΔZkC, ΔZkD) for correcting a relative error of the calculated complex impedance of the storage battery relative to the complex impedance of the reference battery, based on the complex impedance of a reference battery to be compared with the calculated complex impedance of the storage battery and the calculated complex impedance of the storage battery; correcting the calculated complex impedance of the storage battery based on the calculated correction value; A control method for a battery state calculation device, comprising:

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