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

Abstract

A processor (51) executes: calculation processing for calculating an impedance (ZmB, ZmB1-ZmB4) to be measured, which is a complex impedance of a storage battery (10, 100A-100D) when an alternating current is caused to flow in a closed circuit including the storage battery; and correction processing for correcting the calculated impedance to be measured on the basis of a correction value (ΔZ, ΔZ1-ΔZ4) for reducing the influence exerted on the impedance to be measured by a mutual inductance (M2) between a current flow path inside the storage battery and the closed circuit when the alternating current is caused to flow in the closed circuit.

Description

Battery State Calculation Device, Program, and Control Method for Battery State Calculation Device ,

[0009] , ,

[0008] , , <​​​​​​​​​​​​​​​​​​​​​​​​​​​A first aspect of the present disclosure is a battery state calculation device applied to a system having an electrical path connecting the positive and negative terminals of a storage battery, wherein the system includes: an AC drive unit that flows an alternating current through a closed circuit including the electrical path and the storage battery; a voltage detection circuit connected in parallel to the storage battery and detecting the terminal voltage of the storage battery; and a current detection circuit that detects the current flowing through the closed circuit.

[0010] The first embodiment includes a processor, the processor performs the following: acquires a voltage detection value and a current detection value when an alternating current is flowing through a closed circuit including the electrical path and the battery by the AC drive unit with the positive and negative terminals of the battery connected to the electrical path; calculates a measurement target impedance, which is the complex impedance of the battery when an alternating current is flowing through the closed circuit including the electrical path and the battery, based on the acquired voltage detection value and the current detection value; and corrects the calculated measurement target impedance based on a correction value for reducing the influence of the mutual inductance between the current flow path inside the battery and the closed circuit including the electrical path and the battery on the measurement target impedance when an alternating current is flowing through the closed circuit including the electrical path and the battery.

[0011] When alternating current flows through a closed circuit including the electrical path and the battery, the mutual inductance between the current flow path inside the battery and the closed circuit including the electrical path and the battery affects the impedance being measured. The correction value in the first embodiment is a correction value that reduces this effect. Therefore, according to the first embodiment, the accuracy of calculating the complex impedance of the battery can be improved.

[0012] In a second aspect of the present disclosure, the calculation process is a second calculation process, wherein the reference non-interference impedance, which is the complex impedance of a reference battery through which no alternating current is flowing, and the complex impedance of the storage battery through which no alternating current is flowing are equivalent, and the processor performs a first calculation process which calculates a reference interference impedance, which is the complex impedance of the reference battery through which an alternating current is flowing, based on the acquired voltage detection value and current detection value of the closed circuit including the electrical path and the reference battery, with the positive and negative terminals of the reference battery connected to the electrical path, and the AC drive unit is flowing an alternating current.

[0013] In the second embodiment, a reference battery simulating a storage battery is used to calculate the correction value. According to the second embodiment, the accuracy of calculating the complex impedance of the storage battery can be further improved.

[0014] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer from the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is an overall configuration diagram of the system according to the first embodiment; Figure 2 is a perspective view of the battery; Figure 3 is a perspective view of the battery with the battery case and other components omitted; Figure 4 is a schematic diagram showing the main closed circuit and voltage region; Figure 5 is a flowchart showing the procedure for the impedance calculation method; Figure 6 is a diagram showing an example of a reference battery; Figure 7 is a diagram showing an example of a reference battery; Figure 8 is a diagram showing an example of a reference battery; Figure 9 is a diagram showing an overview of the correction method for the impedance to be measured; Figure 10 is an overall configuration diagram of the in-vehicle system according to the second embodiment; Figure 11 is an overall configuration diagram of the measuring device; Figure 12 is a flowchart showing the procedure for the impedance calculation method; and Figure 13 is an overall configuration diagram of the in-vehicle system according to the third embodiment.

[0015] Multiple embodiments will be described with reference to the drawings. In multiple embodiments, functionally and / or structurally corresponding and / or related parts may be given the same reference numeral, or reference numerals that differ by hundreds or more digits. For corresponding and / or related parts, refer to the descriptions of other embodiments.

[0016] <First Embodiment> Hereinafter, a first embodiment of the battery state calculation device according to this disclosure will be described with reference to the drawings.

[0017] The battery state calculation device is a device that calculates the state of a storage battery, and specifically, it is a device that measures the internal impedance of the storage battery. Based on the measured internal impedance, the storage state (specifically, SOC) and degradation state (SOH) of the storage battery are calculated. The battery state calculation device is installed, for example, in a laboratory. In this embodiment, the storage battery is a rechargeable secondary battery, such as a lithium-ion storage battery or a nickel-metal hydride storage battery.

[0018] First, we will explain the overall configuration of system 20 using Figure 1.

[0019] The system 20 to which the battery state calculation device is applied includes a positive electrode voltage path 31, a negative electrode voltage path 32, and a voltage detection unit 33. The positive electrode voltage terminal 31a, which is the first end of the positive electrode voltage path 31, is connected to the positive electrode terminal 10a of the storage battery 10, and the second end 31b of the positive electrode voltage path 31 is connected to the voltage detection unit 33. The negative electrode voltage terminal 32a, which is the first end of the negative electrode voltage path 32, is connected to the negative electrode terminal 10b of the storage battery 10, and the second end 32b of the negative electrode voltage path 32 is connected to the voltage detection unit 33. The voltage detection unit 33 detects the voltage difference between the positive electrode voltage path 31 and the negative electrode voltage path 32 as the terminal voltage of the storage battery 10. In this embodiment, the positive electrode voltage path 31, the negative electrode voltage path 32, and the voltage detection unit 33 correspond to a "voltage detection circuit".

[0020] The system 20 includes an AC power supply 40 as a configuration for generating the current that flows to the storage battery 10. The AC power supply 40 functions as an "AC drive unit" that outputs AC current by being powered by a commercial power supply (not shown) located outside the system 20. The AC power supply 40 may be controlled by either constant current control or constant voltage control, for example.

[0021] The system 20 includes a shunt resistor 41, a current detection unit 42, a positive electrode current path 43, and a negative electrode current path 44 as components for detecting the current flowing through the storage battery 10.

[0022] The first terminal of the AC power supply 40 is connected to the first end of the first electrical path 46a. The second end of the first electrical path 46a is connected to the positive terminal 10a of the storage battery 10. The second terminal of the AC power supply 40 is connected to the first end of the second electrical path 46b. The second end of the second electrical path 46b is connected to the negative terminal 10b of the storage battery 10. A shunt resistor 41 is provided in the second electrical path 46b. In this embodiment, the second end of the first electrical path 46a is configured to have the positive terminal 10a detachably connected, and the second end of the second electrical path 46b is configured to have the negative terminal 10b detachably connected. The AC power supply 40 supplies alternating current to the main closed circuit, which includes the first electrical path 46a, the storage battery 10, the second electrical path 46b, and the shunt resistor 41.

[0023] The positive electrode current path 43 connects the first end of the shunt resistor 41 to the current detection unit 42. The negative electrode current path 44 connects the second end of the shunt resistor 41 to the current detection unit 42. The current detection unit 42 detects the voltage difference between the positive electrode current path 43 and the negative electrode current path 44 as the current flowing to the battery 10. Incidentally, in this embodiment, the shunt resistor 41, the current detection unit 42, the positive electrode current path 43, and the negative electrode current path 44 correspond to the "current detection circuit". Furthermore, the AC power supply 40, the voltage detection unit 33, and the current detection unit 42 are provided, for example, on a circuit board (not shown).

[0024] Figure 1 illustrates an equivalent circuit model of the complex impedance of a battery 10. In this equivalent circuit model, the internal complex impedance of the battery 10 is represented by a series connection of an ohmic resistor 11 and a reaction resistor 12. The ohmic resistor 11 is the current-carrying resistance in the electrodes and electrolyte that constitute the battery 10. The reaction resistor 12 represents the resistance due to the electrode interface reaction at the electrodes and is represented as a parallel connection of a resistive component 12a and a capacitive component 12b. Note that the means of representing the internal impedance of the battery 10 are not limited to the equivalent circuit model.

[0025] System 20 includes a temperature sensor 60 and a pressure sensor 61. The temperature sensor 60 detects the temperature of the battery 10. The pressure sensor 61 detects the pressure (e.g., internal pressure) of the battery 10.

[0026] The battery state calculation device 50 applied to system 20 is an electronic control unit (ECU) and comprises a processor 51 and a storage unit 52 as hardware. In the battery state calculation device 50, the processor 51 and the storage unit 52 are connected to each other via a communication bus 53.

[0027] The memory unit 52 includes memory and storage as hardware. The memory is a storage device for storing data used in the processing of the battery state calculation device 50. The memory provides the processor 51 with a temporary workspace for use when the processor 51 performs processing. The memory includes, for example, ROM or RAM. The storage is a storage device that stores various programs and data for the processor 51 to read and execute, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or flash memory. The storage stores program information and the like for various processes described later.

[0028] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit 52. The recording medium is, for example, a USB memory stick, CD-ROM, or DVD. Also, for example, program information transmitted via a communication network, such as OTA (Over The Air), is installed in the storage unit 52.

[0029] The battery state calculation device 50 receives the detected values ​​from the voltage detection unit 33, the current detection unit 42, the temperature sensor 60, and the pressure sensor 61. Based on the detected values ​​from the voltage detection unit 33 and the current detection unit 42, the battery state calculation device 50 calculates information on the complex impedance (Zm) of the storage battery 10. In other words, based on the detected values ​​from the voltage detection unit 33 and the current detection unit 42, the battery state calculation device 50 calculates the real part (ReZm) and the imaginary part (ImZm) of the complex impedance. Based on the calculation results of the real and imaginary parts, the battery state calculation device 50 creates, for example, a complex impedance plane plot (Call-Call plot) to understand the characteristics of electrodes and electrolytes. For example, the battery state calculation device 50 understands the state of charge (SOC) and the state of degradation (SOH).

[0030] A specific example of the storage battery 10 will be explained using Figures 2 and 3. Figure 3 is a diagram of the configuration shown in Figure 2, with the battery case 16 and other components omitted.

[0031] The storage battery 10 comprises a winding body 13 and a battery case 16. The winding body 13 is constructed by winding a negative electrode sheet, a positive electrode sheet, and a separator in a stacked state. The winding body 13 has a flat rectangular parallelepiped shape. A positive electrode side current collector 14a is provided at the first end of the winding body 13 in the first direction (width direction), and a negative electrode side current collector 14b is provided at the second end of the winding body 13 in the width direction. Each current collector 14a, 14b extends in a third direction (height direction) perpendicular to the width direction and second direction (thickness direction) of the winding body 13.

[0032] 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. The winding body 13, each current collector 14a, 14b, and each conductive member 15a, 15b are housed in the battery case 16.

[0033] Hereafter, the positive electrode current collector 14a and the positive electrode conductive member 15a will be collectively referred to as the positive electrode path 16a, and the negative electrode current collector 14b and the negative electrode conductive member 15b will be collectively referred to as the negative electrode path 16b.

[0034] However, there is a concern that the calculation accuracy of the complex impedance of the battery 10 will decrease. This is because the detected value of the voltage detection unit 33 contains errors. The reason for these errors will be explained below using Figure 4.

[0035] In Figure 4, P1 indicates the position of the end of the positive electrode path 16a opposite to the positive electrode terminal 10a, and P2 indicates the position of the positive electrode terminal 10a. P3 indicates the position of the first terminal of the AC power supply 40, and P4 indicates the position of the second terminal of the AC power supply 40. P5 indicates the position of the negative electrode terminal 10b, and P6 indicates the position of the end of the negative electrode path 16b opposite to the negative electrode terminal 10b. P7 indicates the position of the second end 31b of the positive electrode side voltage path 31, and P8 indicates the position of the second end 32b of the negative electrode side voltage path 32.

[0036] The main closed circuit described above is a closed circuit in the order P1→P2→P3→P4→P5→P6→P1. When current flows through the main closed circuit, current flows throughout the entire wound body 13. For this reason, in this embodiment, the main closed circuit also includes the entire wound body 13.

[0037] The region enclosed by P7→P2→P5→P8→P7 represents the external voltage region 34. The region enclosed by P2→P1→P6→P5→P2 represents the internal voltage region 35. In this embodiment, the internal voltage region 35 also includes the entire wound body 13. The internal voltage region 35 is the region of the internal structure of the battery 10 and also includes the current flow path inside the battery 10.

[0038] When an alternating current flows through the battery 10 using the AC power supply 40, a magnetic field is generated. When the generated magnetic field links the external voltage region 34 and the internal voltage region 35, an induced electromotive force is generated in the current flow path that constitutes each voltage region 34 and 35. In this case, a detection error occurs in the voltage detected by the voltage detection unit 33 via the positive electrode voltage path 31 and the negative electrode voltage path 32. If the detected value of the voltage detection unit 33 contains a detection error, there is a concern that the accuracy of calculating the complex impedance of the battery 10 will decrease. Therefore, in this embodiment, a technology that can improve the accuracy of calculating the complex impedance is employed.

[0039] Figure 5 is a flowchart of the impedance correction method.

[0040] In step S10, the positive terminal of the reference battery is connected to the second end and positive voltage terminal 31a of the first electrical path 46a, and the negative terminal of the reference battery is connected to the second end and second end 31b of the second electrical path 46b. The system 20 may also include a constant temperature bath in which the reference battery or storage battery 10 is housed.

[0041] The reference battery is a device that simulates the storage battery 10 which is the measurement object of complex impedance. The reference non-interference impedance Za which is the complex impedance of the reference battery when no alternating current is flowing is equivalent to the complex impedance Zb of the storage battery 10 when no alternating current is flowing. Information on the reference non-interference impedance of the reference battery is stored in the storage unit 52. The reference non-interference impedance can be obtained, for example, by experiment or calculation.

[0042] Incidentally, let the resistance value of the DC resistance component of the reference battery be R1, the resistance value of the DC resistance component of the storage battery 10 be R2, the larger one of R1 and R2 be RH, and the smaller one be RL. That the reference non-interference impedance Za is equivalent to the complex impedance of the storage battery 10 when no alternating current is flowing means, for example, "0.7×RH ≤ RL < RH", "0.8×RH ≤ RL < RH", "0.9×RH ≤ RL < RH" or "0.95×RH ≤ RL < RH". To make them equivalent, for example, the case and the internal structure of the case of the reference battery may be made the same as those of the case and the internal structure of the storage battery 10.

[0043] When the positive electrode terminal of the reference battery is connected to the second end of the first electric path 46a and the positive electrode voltage terminal 31a, and the negative electrode terminal of the reference battery is connected to the second end of the second electric path 46b and the second end 31b, in the system 20, the relative positions of the battery state calculation device 50, the reference battery, the positive electrode side voltage path 31, the negative electrode side voltage path 32, the voltage detection unit 33, the first electric path 46a, the second electric path 46b, the current detection unit 42, the positive electrode side current path 43 and the negative electrode side current path 44 are in a fixed state.

[0044] Incidentally, as the reference battery, instead of the one having the same configuration as the storage battery 10 shown in FIGS. 2 and 3, for example, those shown in FIGS. 6 to 8 can be used.

[0045] FIG. 6 shows an example of a reference battery 70 in which a plate-like conductor 71 is used instead of the wound body. The conductor 71 has a rectangular shape. The reference battery 70 includes a positive electrode side conductive member 72a provided at the first end in the width direction of the conductor 71 and a negative electrode side conductive member 72b provided at the second end in the width direction of the conductor 71. The reference battery 70 includes a positive electrode terminal 70a provided on the positive electrode side conductive member 72 and a negative electrode terminal 70b provided on the negative electrode side conductive member 72.

[0046] The plate thickness dimension of the conductor 71 shown in FIG. 6 is the same throughout the entire area of the conductor 71. In this case, in the conductor 71, the closer the region is to each of the terminals 70a and 70b, the greater the current flowing through it.

[0047] Therefore, as shown in FIG. 7, in the conductor 81, a reference battery 80 in which the plate thickness dimension becomes smaller in the region closer to the positive electrode terminal 80a and the negative electrode terminal 80b may be used. In this case, in the conductor 81, the closer the region is to the positive electrode terminal 80a and the negative electrode terminal 80b, the smaller the resistance value. As a result, the current flowing through the entire area of the conductor 81 can be equalized. Note that the reference battery 80 in FIG. 7 includes a positive electrode side conductive member 82a and a negative electrode side conductive member 82b, similar to the reference battery 70 in FIG. 6.

[0048] FIG. 8 shows a wound body 92 formed by winding a laminate of a conductor sheet 90 and an insulating sheet 91 instead of the wound body 13 in FIG. 3 in the reference battery.

[0049] Returning to the description of FIG. 5, in the subsequent step S11, the battery state calculation device 50 determines whether or not the temperature condition is satisfied. The temperature condition is a condition that the detected temperature Tbr of the reference battery detected by the temperature sensor 60 is the target temperature Ttgt, or a condition that the detected temperature Tbr is equivalent to the target temperature Ttgt. That the detected temperature Tbr is equivalent to the target temperature Ttgt means, for example, "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".

[0050] If the battery state calculation device 50 determines that the temperature conditions are met, it proceeds to step S12 and controls the AC power supply 40 to supply AC current to the main closed circuit including the reference battery. In controlling the AC power supply 40, the battery state calculation device 50 performs a frequency sweep to gradually change (increase or decrease) the angular frequency ω of the AC current. With AC current flowing through the reference battery, the battery state calculation device 50 acquires the detected current ImA from the current detection unit 42 and the detected voltage VmA from the voltage detection unit 33. Specifically, the battery state calculation device 50 acquires the detected current ImA and detected voltage VmA corresponding to the angular frequency ω of the AC current.

[0051] In step S13, the battery state calculation device 50 calculates the reference interference impedance ZmA, which is the complex impedance (= VmA / ImA) of the reference battery, based on the acquired detected current ImA and detected voltage VmA. The reference interference impedance ZmA includes errors caused by the external voltage region 34 and the mutual inductance M1 of the main closed circuit when AC current flows through the main closed circuit, and errors caused by the internal voltage region 35 and the mutual inductance M2 of the main closed circuit when AC current flows through the main closed circuit. In this embodiment, the processing in steps S12 and S13 corresponds to the "first calculation process".

[0052] In step S14, the battery state calculation device 50 reads and obtains the reference non-interference impedance Za from the storage unit 52.

[0053] In step S15, the battery state calculation device 50 calculates a correction value ΔZ by subtracting the reference non-interference impedance Za obtained in step S14 from the reference interference impedance ZmA calculated in step S13 (see Figure 9(A)). The correction value ΔZ is calculated corresponding to each angular frequency ω. The correction value ΔZ is, for example, a value composed only of the imaginary part, and becomes a larger value as the angular frequency ω increases (ΔZ∝j×ω). In this embodiment, the process in step S15 corresponds to the "correction value calculation process".

[0054] In step S16, the battery state calculation device 50 stores the calculated correction value ΔZ in the storage unit 52, linked to the angular frequency ω.

[0055] In the following step S17, the positive terminal of the reference battery is disconnected from the second end of the first electrical path 46a and the positive voltage terminal 31a, and the negative terminal of the reference battery is disconnected from the second end and second end 31b of the second electrical path 46b. Then, in place of the reference battery, the positive terminal 10a of the storage battery 10 is connected to the second end and positive voltage terminal 31a of the first electrical path 46a, and the negative terminal 10b of the storage battery 10 is connected to the second end and second end 31b of the second electrical path 46b. As a result, in the system 20, the relative positions of the battery state calculation device 50, the storage battery 10, the positive voltage path 31, the negative voltage path 32, the voltage detection unit 33, the first electrical path 46a, the second electrical path 46b, the current detection unit 42, the positive current path 43, and the negative current path 44 are fixed. The storage battery 10 may be housed in the constant temperature bath.

[0056] In the following step S18, the battery state calculation device 50 determines whether the temperature condition is met. The temperature condition is the same as the temperature condition in step S11, which is that the detected temperature Tbr of the storage battery 10 detected by the temperature sensor 60 is the target temperature Ttgt, or that the detected temperature Tbr is equivalent to the target temperature Ttgt.

[0057] In addition to the temperature condition, a pressure condition for the battery 10 may be added in step S18. The pressure condition is that the pressure detected by the pressure sensor 61 is equal to the target pressure, or that the detected pressure is equivalent to the target pressure.

[0058] If the battery state calculation device 50 determines that the temperature conditions are met, it proceeds to step S19 and controls the AC power supply 40 to supply AC current to the main closed circuit including the storage battery 10. In controlling the AC power supply 40, the battery state calculation device 50 performs a frequency sweep to gradually change (increase or decrease) the angular frequency ω of the AC current. With AC current flowing through the storage battery 10, the battery state calculation device 50 acquires the detected current ImB from the current detection unit 42 and the detected voltage VmB from the voltage detection unit 33. Specifically, the battery state calculation device 50 acquires the detected current ImB and detected voltage VmB corresponding to the angular frequency ω of the AC current.

[0059] In step S20, the battery state calculation device 50 calculates the measured impedance ZmB (= VmB / ImB), which is the complex impedance of the storage battery 10, based on the acquired detected current ImB and detected voltage VmB. The measured impedance ZmB includes errors caused by the first mutual inductance M1 and errors caused by the second mutual inductance M2. The first mutual inductance M1 is the mutual inductance between the current flow path in the external voltage region 34 and the main closed circuit when an alternating current flows through the main closed circuit. The second mutual inductance M2 is the mutual inductance between the current flow path in the internal voltage region 35 and the main closed circuit when an alternating current flows through the main closed circuit. In this embodiment, the processing in steps S19 and S20 corresponds to the "second calculation process".

[0060] In step S21, the battery state calculation device 50 calculates the corrected impedance ZmC by subtracting the correction value ΔZ stored in the storage unit 52 from the calculated measured impedance ZmB (see Figures 9(B) and 9(C)). The corrected impedance ZmC is the complex impedance of the winding body 13 of the storage battery 10. In this embodiment, the process in step S21 corresponds to the "correction process".

[0061] According to the embodiment described above, a corrected impedance ZmC can be calculated from the measured impedance ZmB, with the influence of errors caused by the mutual inductances M1 and M2 reduced. This improves the accuracy of calculating the complex impedance of the battery 10. Furthermore, according to this embodiment, the influence of errors caused by the mutual inductances M1 and M2 can be reduced from the measured impedance ZmB without disassembling the battery 10. In addition, according to this embodiment, the battery 10 can be handled non-destructively, reducing the man-hours required for measurement and improving safety by avoiding contact with harmful chemicals inside the battery 10.

[0062] The degree to which the magnetic flux generated when alternating current flows through the main closed circuit influences the detected value of the voltage detection unit 33 changes when the relative positions of the battery state calculation device 50, reference battery (or storage battery 10), positive electrode voltage path 31, negative electrode voltage path 32, voltage detection unit 33, first electrical path 46a, second electrical path 46b, current detection unit 42, positive electrode current path 43, and negative electrode current path 44 change in the system 20. Conversely, the degree to which the magnetic flux generated when alternating current flows through the main closed circuit influences the detected value of the voltage detection unit 33 is small if the relative positions are fixed.

[0063] In this embodiment, since the series of processes shown in Figure 5 are performed with the relative positions fixed, the accuracy of calculating the correction value ΔZ can be improved. As a result, the accuracy of calculating the complex impedance of the battery 10 can be further improved.

[0064] As illustrated in Figure 9, the method of this embodiment is effective for storage batteries where the ratio of the reference non-interference impedance Za to the impedance ZmB being measured is small.

[0065] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, as shown in Figure 10, the complex impedance of the battery 110 mounted on the vehicle 200 is calculated.

[0066] The storage battery 110 comprises a series connection of multiple unit batteries 100. In this embodiment, for convenience, the storage battery 110 comprises four unit batteries 100, namely the first, second, third, and fourth unit batteries 100A, 100B, 100C, and 100D. Each unit battery 100A, 100B, 100C, and 100D is equipped with a positive terminal 101a and a negative terminal 101b. Each unit battery 100A, 100B, 100C, and 100D is a battery of the same specifications, specifically having the same rated voltage and full charge capacity. A unit battery is a single battery cell or a series connection of multiple battery cells.

[0067] The system mounted on the vehicle 200 includes an inverter 130, a rotating electric machine 140, and a relay SMR. The inverter 130 has multiple series connections of upper arm switches SH and lower arm switches SL for three phases. The armature windings of the rotating electric machine 140 are connected to the connection points of the upper arm switches SH and lower arm switches SL. The rotor of the rotating electric machine 140 is capable of transmitting power to the drive wheels 150 of the vehicle 200. The inverter 130 and the battery 110 are connected via a relay SMR.

[0068] 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 in order to drive the vehicle 200.

[0069] In this embodiment, the temperature sensor 60 detects the temperature of each unit battery 100A, 100B, 100C, and 100D. The pressure sensor 61 detects the pressure of each unit battery 100A, 100B, 100C, and 100D.

[0070] In this embodiment, before the storage battery 110 is installed in the vehicle 200, the complex impedance of each unit battery 100A, 100B, 100C, and 100D is calculated at the factory. The measuring device 300 shown in Figure 11 is installed, for example, on the factory line. Similar to the first embodiment, the measuring device 300 includes a voltage detection unit 33, an AC power supply 40, a current detection unit 42, and a battery state calculation device 50. The voltage detection unit 33 is provided individually for each unit battery 100A, 100B, 100C, and 100D.

[0071] In this embodiment, a reference battery is used that comprises a series connection of multiple (specifically four) unit batteries. The reference battery is a device that simulates a storage battery 110, and has a configuration similar to that of a storage battery 110. The first to fourth reference unit batteries, which constitute the reference battery, have a configuration similar to the first to fourth unit batteries 100A to 100D that constitute the storage battery 110. The reference non-interference impedances Za1 to Za4, which are the complex impedances of each reference unit battery through which no alternating current flows, are equivalent to the complex impedances of each unit battery 100A to 100D through which no alternating current flows. Information on the reference non-interference impedances Za1 to Za4 of each reference unit battery is stored in the storage unit 52.

[0072] Let Ra1, Ra2, Ra3, and Ra4 be the DC resistance values ​​of each reference unit battery that makes up the reference battery. The larger of the average value of the DC resistance values ​​of each reference unit battery that makes up the reference battery (= (|Ra1| + |Ra2| + |Ra3| + |Ra4|) / 4) and the average value of the DC resistance values ​​of each unit battery 100A, 100B, 100C, and 100D through which no AC current flows is denoted as RH, and the smaller of the two is denoted as RL. The reference non-interference impedances Za1 to Za4 of each reference unit battery and the complex impedances of each unit battery 100A to 100D through which no AC current flows are equivalent if, for example, "0.7 × RH ≤ RL < RH", "0.8 × RH ≤ RL < RH", "0.9 × RH ≤ RL < RH", or "0.95 × RH ≤ RL < RH".

[0073] Figure 12 is a flowchart of the impedance correction method.

[0074] In step S30, the positive terminal of the first reference unit battery is connected to the second end of the first electrical path 46a, and the negative terminal of the fourth reference unit battery is connected to the second end of the second electrical path 46b. In addition, the positive terminals of the first to fourth reference unit batteries are connected to the positive voltage terminal 31a of the positive voltage path 31, and the negative terminals of the first to fourth reference unit batteries are connected to the negative voltage terminal 32a of the negative voltage path 32.

[0075] In the following step S31, the battery state calculation device 50 determines whether the temperature condition is met. The temperature condition is that the temperatures of the first to fourth reference unit batteries detected by the temperature sensor 60 are the same or equivalent. The temperatures of the first to fourth reference unit batteries being equivalent means that the absolute value of the difference ΔT between the highest temperature and the lowest temperature of each reference unit battery is, for example, 5°C or less, 3°C or less, 1°C or less, or 0.5°C or less.

[0076] If the battery state calculation device 50 determines that the temperature conditions are met, it proceeds to step S32 and controls the AC power supply 40 to supply AC current to the main closed circuit including the first to fourth reference unit batteries. In controlling the AC power supply 40, the battery state calculation device 50 performs a frequency sweep to gradually change (increase or decrease) the angular frequency ω of the AC current. With AC current flowing through each reference unit battery, the battery state calculation device 50 acquires the detected current ImA from the current detection unit 42 and the detected voltages VmA1, VmA2, VmA3, VmA4 from each voltage detection unit 33. Specifically, the battery state calculation device 50 acquires the detected current ImA and the detected voltages VmA1, VmA2, VmA3, VmA4 corresponding to the angular frequency ω of the AC current.

[0077] In step S34, the battery state calculation device 50 calculates the first reference interference impedance ZmA1 (=VmA1 / ImA), which is the complex impedance of the first reference unit battery; the second reference interference impedance ZmA2 (=VmA2 / ImA) of the second reference unit battery; the third reference interference impedance ZmA3 (=VmA3 / ImA) of the third reference unit battery; and the fourth reference interference impedance ZmA4 (=VmA4 / ImA) of the fourth reference unit battery, based on the acquired detected current ImA and detected voltages VmA1, VmA2, VmA3, and VmA4. In this embodiment, the processing in steps S32 and S33 corresponds to the "first calculation process".

[0078] In step S34, the battery state calculation device 50 reads and acquires the first, second, third, and fourth reference non-interference impedances Za1, Za2, Za3, and Za4 from the storage unit 52.

[0079] In step S35, the battery state calculation device 50 calculates the first correction value ΔZ1 by subtracting the acquired first reference non-interference impedance Za1 from the calculated first reference interference impedance ZmA1. The battery state calculation device 50 calculates the second correction value ΔZ2 by subtracting the acquired second reference non-interference impedance Za2 from the calculated second reference interference impedance ZmA2. The battery state calculation device 50 calculates the third correction value ΔZ3 by subtracting the acquired third reference non-interference impedance Za3 from the calculated third reference interference impedance ZmA3. The battery state calculation device 50 calculates the fourth correction value ΔZ4 by subtracting the acquired fourth reference non-interference impedance Za4 from the calculated fourth reference interference impedance ZmA4. In this embodiment, the process in step S35 corresponds to the "correction value calculation process".

[0080] In step S36, the battery state calculation device 50 stores the calculated correction values ​​ΔZ1, ΔZ2, ΔZ3, and ΔZ4 in the storage unit 52, linked to the angular frequency ω. The battery state calculation device 50 may, for example, store the calculated correction values ​​ΔZ1, ΔZ2, ΔZ3, and ΔZ4 in the storage unit of the ECU provided in the vehicle 200.

[0081] In step S37, the positive terminal of the first reference unit battery is removed from the second end of the first electrical path 46a, and the negative terminal of the fourth reference unit battery is removed from the second end of the second electrical path 46b. In addition, the positive terminals of the first to fourth reference unit batteries are removed from the positive voltage terminal 31a of the positive voltage path 31, and the negative terminals of the first to fourth reference unit batteries are removed from the negative voltage terminal 32a of the negative voltage path 32.

[0082] Subsequently, the positive terminal 101a of the first unit battery 100A is connected to the second end of the first electrical path 46a, and the negative terminal 101b of the fourth unit battery 100D is connected to the second end of the second electrical path 46b. In addition, the positive terminals 101a of the first to fourth unit batteries 100A to 100D are connected to the positive voltage terminal 31a of the positive voltage path 31, and the negative terminals 101b of the first to fourth unit batteries 100A to 100D are connected to the negative voltage terminal 32a of the negative voltage path 32.

[0083] In the following step S38, the battery state calculation device 50 determines whether or not the temperature condition is met. The temperature condition is the same as the temperature condition in step S31.

[0084] If the battery state calculation device 50 determines that the temperature conditions are met, it proceeds to step S39 and controls the AC power supply 40 to supply AC current to the main closed circuit including the first to fourth unit batteries 100A to 100D. In controlling the AC power supply 40, the battery state calculation device 50 performs a frequency sweep to gradually change (increase or decrease) the angular frequency ω of the AC current. With AC current flowing through the reference battery, the battery state calculation device 50 acquires the detected current ImB from the current detection unit 42 and the detected voltages VmB1, VmB2, VmB3, VmB4 from each voltage detection unit 33. Specifically, the battery state calculation device 50 acquires the detected current ImB and each detected voltage VmB1, VmB2, VmB3, VmB4 corresponding to the angular frequency ω of the AC current.

[0085] In step S40, the battery state calculation device 50 calculates the first measured impedance ZmB1 (=VmB1 / ImB), which is the complex impedance of the first unit battery 100A; the second measured impedance ZmB2 (=VmB2 / ImB) of the second unit battery 100B; the third measured impedance ZmB3 (=VmB3 / ImB) of the third unit battery 100C; and the fourth measured impedance ZmB4 (=VmB4 / ImB) of the fourth unit battery 100D, based on the acquired detected current ImB and detected voltages VmB1, VmB2, VmB3, and VmB4. In this embodiment, the processing in steps S39 and S40 corresponds to the "second calculation process".

[0086] In step S41, the battery state calculation device 50 calculates the first, second, third, and fourth corrected impedances ZmC1, ZmC2, ZmC3, and ZmC4 by subtracting the first, second, third, and fourth correction values ​​ΔZ1, ΔZ2, ΔZ3, and ΔZ4 stored in the storage unit 52 from the calculated first, second, third, and fourth measurement target impedances ZmB1, ZmB2, ZmB3, and ZmB4. In this embodiment, the process in step S41 corresponds to the "correction process".

[0087] According to the embodiment described above, correction values ​​ΔZ1 to ΔZ4 can be calculated individually for each unit battery 100A to 100D. This improves the accuracy of calculating the complex impedance of each unit battery 100A to 100D.

[0088] The calculated correction values ​​ΔZ1 to ΔZ4 are stored in the memory of the vehicle 200's ECU. In vehicle 200, the correction values ​​ΔZ1 to ΔZ4 are used to accurately determine the battery status.

[0089] In the method shown in Figure 12, steps S30 to S36 may be performed, for example, before the factory starts operations and may not be performed after the factory starts operations.

[0090] <Modification of the Second Embodiment> The correction process of the second embodiment may be performed in an inspection process at a vehicle dealership, for example, instead of at a factory.

[0091] <Third Embodiment> The third embodiment will be described below, focusing on the differences from the second embodiment, with reference to the drawings. In this embodiment, as shown in Figure 13, the complex impedance of each unit battery 100A to 100D mounted on the vehicle 200 is calculated.

[0092] The system mounted on the vehicle 200 includes a DC-DC converter 160 and a low-voltage battery 161. The rated voltage of the low-voltage battery 161 is lower than the rated voltage of the battery 110. The DC-DC converter 160 boosts the output voltage of the low-voltage battery 161 and supplies it to the battery 110. In this embodiment, the DC-DC converter 160 corresponds to the "AC drive unit".

[0093] The system includes a monitoring IC 170. The monitoring IC 170 includes a voltage detection unit 33, a current detection unit 42, and a control unit 171, each individually provided for each unit battery 100A, 100B, 100C, and 100D. The voltage detection unit 33 and the positive terminal 101a are connected by a positive-side voltage path 31, and the voltage detection unit 33 and the negative terminal 101b are connected by a negative-side voltage path 32.

[0094] The control unit 171 receives the detected values ​​from the voltage detection unit 33, the current detection unit 42, the temperature sensor 60, and the pressure sensor 61. The control unit 171 has the same functions as the battery state calculation device 50. Based on the detected values ​​from the voltage detection unit 33 and the current detection unit 42, the control unit 171 calculates the real and imaginary parts of the complex impedance of each unit battery 100A, 100B, 100C, and 100D. Based on the calculation results, the control unit 171 creates, for example, a complex impedance plane plot (Call-Call plot) to understand the state of charge (SOC) and state of degradation (SOH) of each unit battery 100A, 100B, 100C, and 100D.

[0095] The impedance correction in this embodiment is performed in the same manner as in steps S38 to S41 in Figure 12. The main changes from the steps in Figure 12 will be described below.

[0096] In step S39, the battery state calculation device 50 controls the DC-DC converter 160 to supply AC current to the main closed circuit, which includes each unit battery 100A, 100B, 100C, and 100D, using the low-voltage storage battery 161 as the power source.

[0097] In this embodiment, the first, second, third, and fourth correction values ​​ΔZ1, ΔZ2, ΔZ3, and ΔZ4 are calculated in advance by experiment or calculation and are stored in the storage unit 52. In step S41, the battery state calculation device 50 can read and obtain the first, second, third, and fourth correction values ​​ΔZ1, ΔZ2, ΔZ3, and ΔZ4 from the storage unit 52.

[0098] According to the embodiment described above, with the storage battery 110 mounted on the vehicle 200, the complex impedance of each unit battery 100A, 100B, 100C, and 100D constituting the storage battery 110 can be calculated with high accuracy.

[0099] <Other Embodiments> The above embodiments may be modified and implemented as follows.

[0100] In the third embodiment, impedance correction processing may be performed on an external server (e.g., a cloud server) instead of the control unit 171 provided in the vehicle 200. In this case, the server can collect correction values ​​corresponding to a large number of vehicles and store the collected correction values ​​in the server's memory. The server may, for example, send statistical values ​​(e.g., average values) of the collected correction values ​​to the ECU of each vehicle as the correction value.

[0101] Various types of batteries can be used in vehicles. For example, long, plate-shaped blade cells may be used as batteries.

[0102] Alternatively, the storage battery may be configured by grouping multiple individual batteries (e.g., battery cells) into a battery block and then connecting each battery block in series.

[0103] Furthermore, the battery may be configured as a so-called CTP (Cell to Pack) system, in which a series connection of multiple battery cells is housed in a compartment of the vehicle's chassis, without the need to create a battery block.

[0104] Alternatively, instead of the CTP configuration, a so-called CTC (Cell to Chassis) configuration may be used, in which a housing for battery cells is configured in the vehicle's chassis, and multiple battery cells are housed in the housing.

[0105] The storage battery is not limited to secondary batteries; for example, a fuel cell could also be used.

[0106] The mobile device on which the battery status calculation device is mounted is not limited to a vehicle; for example, it may be an aircraft or a ship. Furthermore, the mounting location of the battery status calculation device is not limited to a mobile device; it may be a stationary device.

[0107] In this disclosure or claims, the term "processor" means one or more hardware processors configured to execute processing defined by computer program code (i.e., one or more instructions of a computer program) contained in a computer program by reading the computer program code each time. In other words, a "processor" is a hardware device that executes one or more programmed processes. Therefore, computer program code can also be said to be software that can define the processing of the processor according to its content. A "processor" can be a general-purpose or specific-purpose processor, and may be, but is not limited to, a CPU, microprocessor, GPU, and DFP (Data Flow Processor).

[0108] In this disclosure or claims, the term “memory” means one or more hardware memories that are non-transitional tangible recording media configured to record computer program code and / or data in a manner accessible from a processor. “Memory” can be implemented by memory technology such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code that constitutes the program is recorded in memory and executed by a processor, thereby enabling the processor to perform the various functions described above.

[0109] In this disclosure or claims, the term “circuit” refers to one or more logic circuits as hardware, configured to perform specific processing defined by a pre-designed circuit configuration. In other words (and, in contrast to “processor”), “circuit” in this disclosure or claims refers to a hardware device that performs specific processing based on a circuit configuration, rather than processing defined by software such as the computer program code described above. For example, “circuit” may include custom ICs such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) designed with Hardware Description Language (HDL). That is, “circuit” in this disclosure or claims includes all hardware circuits except for the processors described above that perform processing by reading computer program code.

[0110] In this disclosure or claims, the expression "at least one of the circuit and processor" should be interpreted as disjunctive (logical OR) and not as "at least one circuit and at least one processor." Therefore, in this disclosure or claims, "at least one of the circuit and processor causes the control device to perform functions" includes cases where the circuit alone causes the device to perform all functions. Also, "at least one of the circuit and processor causes the device to perform functions" includes cases where the processor alone causes the device to perform all functions. Furthermore, "at least one of the circuit and processor causes the device to perform functions" includes cases where the circuit causes the device to perform some functions and the processor causes the device to perform the remaining functions. In the last example, for example, if the device performs functions A to C, functions A and B may be implemented by the circuit, and the remaining function C may be implemented by the processor.

[0111] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A battery state calculation device (50, 171) applied to a system (20) having an electrical path (46a, 46b) connecting the positive terminals (10a, 101a) and negative terminals (10b, 101b) of a storage battery (10, 100A to 100D), wherein the system includes: an AC drive unit (40, 160) that flows 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 the terminal voltage of the storage battery; a current detection circuit (41 to 44) that detects the current flowing through the closed circuit; and a processor (51), the processor being: A battery state calculation device that performs the following steps: acquiring the detected values ​​of the voltage detection circuit and the current detection circuit when an alternating current is flowing through the closed circuit including the electrical circuit and the battery by the AC drive unit with the positive and negative terminals of the battery connected to the electrical circuit, and calculating the target impedance (ZmB, ZmB1 to ZmB4), which is the complex impedance of the battery when an alternating current is flowing through the closed circuit including the electrical circuit and the battery, based on the acquired detected values ​​of the voltage detection circuit and the current detection circuit; and correcting the calculated target impedance based on correction values ​​(ΔZ, ΔZ1 to ΔZ4) for reducing the influence of the mutual inductance (M2) between the current flow path inside the battery and the closed circuit including the electrical circuit and the battery on the target impedance when an alternating current is flowing through the closed circuit including the electrical circuit and the battery.

2. The calculation process is a second calculation process, wherein the reference non-interference impedance (Za, Za1 to Za4), which is the complex impedance of the reference battery (70, 80) through which no AC current is flowing, is equivalent to the complex impedance of the storage battery through which no AC current is flowing, and the processor obtains the detected values ​​of the voltage detection circuit and the current detection circuit when AC current is flowing through the closed circuit including the electrical path and the reference battery by the AC drive unit with the positive and negative terminals of the reference battery connected to the electrical path, and calculates the reference interference impedance (ZmA, ZmA1 to ZmA4), which is the complex impedance of the reference battery when AC current is flowing through the closed circuit including the electrical path and the reference battery, based on the obtained detected values ​​of the voltage detection circuit and the current detection circuit, in a first calculation process, A battery state calculation device according to claim 1, comprising: calculating a correction value calculation process based on the calculated reference interference impedance and the reference non-interference impedance to further reduce the influence of the mutual inductance (M1) between the closed circuit including the electrical path and the battery and the voltage detection circuit on the impedance to be measured when an alternating current is flowing through the closed circuit including the electrical path and the battery.

3. The storage battery is a series connection of a plurality of unit batteries (100A to 100D), and the reference non-interference impedance of each unit battery constituting the reference battery through which no AC current flows is equivalent to the complex impedance of each unit battery constituting the storage battery through which no AC current flows, and the voltage detection circuit is provided individually corresponding to each unit battery, and the processor, as the first calculation process, acquires the detected values ​​of each voltage detection circuit and the detected values ​​of the current detection circuit when the positive and negative terminals of the reference battery are connected to the electrical path and AC current is flowing through the closed circuit including the reference battery and the electrical path by the AC drive unit, and performs a process to calculate the reference interference impedance (ZmA1 to ZmA4) of each unit battery constituting the reference battery based on the acquired detected values ​​of each voltage detection circuit and the detected values ​​of the current detection circuit, and as the second calculation process, A battery state calculation device according to claim 2, wherein the positive and negative terminals of the storage battery are connected to the electrical path, and an alternating current is flowing through the closed circuit including the storage battery and the electrical path by the AC drive unit, the device acquires the detected values ​​of each voltage detection circuit and the detected values ​​of the current detection circuit, and performs a process to calculate the measured impedance (ZmB1 to ZmB4) of each unit battery constituting the storage battery based on the acquired detected values ​​of each voltage detection circuit and the detected values ​​of the current detection circuit, and as a correction value calculation process, the device performs a process to calculate individual correction values ​​(ΔZ1 to ΔZ4) for each unit battery constituting the storage battery based on the calculated reference interference impedance of each unit battery and the reference non-interference impedance (Za1 to Za4) of each unit battery constituting the reference battery, and as a correction process, the device performs a process to correct the measured impedance based on the correction values ​​in each unit battery constituting the storage battery.

4. The battery state calculation device according to claim 2 or 3, wherein the system is configured such that the relative positions of the electrical path, the voltage detection circuit and the current detection circuit are fixed, and the processor, in the second calculation process, acquires the detected value of the voltage detection circuit and the detected value of the current detection circuit while the relative positions are fixed.

5. The battery state calculation device according to claim 2 or 3, wherein the shape of the conductor (81) is such that the current distribution of the conductor within the reference battery is equalized.

6. The battery state calculation device according to claim 3, wherein the system and the battery state calculation device are mounted on a mobile body (200), and include a storage unit (52), and the processor performs a process of storing the calculated correction value in the storage unit.

7. The battery state calculation device according to claim 1, wherein the system and the battery state calculation device are mounted on a mobile body (200), the storage battery is a series connection of a plurality of unit batteries (100A to 100D), the voltage detection circuit is provided individually for each of the unit batteries, and the processor performs the correction process with the storage battery mounted on the mobile body.

8. A program applied to a system (20) comprising an electrical path (46a, 46b) connecting the positive terminals (10a, 101a) and negative terminals (10b, 101b) of a storage battery (10, 100A to 100D), wherein the system comprises: an AC drive unit (40, 160) that supplies alternating current to 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 the terminal voltage of the storage battery; and a current detection circuit (41 to 44) that detects the current flowing through the closed circuit, wherein at least one of the processor (51) and the circuit, A program that performs the following steps: acquiring the detected values ​​of the voltage detection circuit and the current detection circuit when the positive and negative terminals of the battery are connected to the electrical path and an alternating current is flowing through the closed circuit including the electrical path and the battery by the AC drive unit, and calculating the target impedance (ZmB, ZmB1 to ZmB4), which is the complex impedance of the battery when an alternating current is flowing through the closed circuit including the electrical path and the battery, based on the acquired detected values ​​of the voltage detection circuit and the current detection circuit; and correcting the calculated target impedance based on correction values ​​(ΔZ, ΔZ1 to ΔZ4) to reduce the influence of the mutual inductance (M2) between the current flow path inside the battery and the closed circuit including the electrical path and the battery on the target impedance when an alternating current is flowing through the closed circuit including the electrical path and the battery.

9. A control method for a battery state calculation device (50, 171) applied to a system (20) comprising an electrical path (46a, 46b) connecting the positive terminals (10a, 101a) and negative terminals (10b, 101b) of a storage battery (10, 100A to 100D), wherein the system comprises: an AC drive unit (40, 160) that flows 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 the terminal voltage of the storage battery; and a current detection circuit (41 to 44) that detects the current flowing through the closed circuit, and a processor (51) and at least one of the circuits, A control method for a battery state calculation device, comprising: a calculation process to obtain the detected values ​​of the voltage detection circuit and the current detection circuit when an alternating current is flowing through the closed circuit including the electrical circuit and the battery by the AC drive unit with the positive and negative terminals of the battery connected to the electrical circuit; a calculation process to calculate the target impedance (ZmB, ZmB1 to ZmB4), which is the complex impedance of the battery when an alternating current is flowing through the closed circuit including the electrical circuit and the battery, based on the obtained detected values ​​of the voltage detection circuit and the current detection circuit; and a correction process to correct the calculated target impedance based on correction values ​​(ΔZ, ΔZ1 to ΔZ4) for reducing the influence of the mutual inductance (M2) between the current flow path inside the battery and the closed circuit including the electrical circuit and the battery on the target impedance when an alternating current is flowing through the closed circuit including the electrical circuit and the battery.

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