Battery monitoring device and battery monitoring method

Abstract

A battery monitoring device (201) is provided with: a signal generation unit that generates a control signal for controlling a first measurement circuit (1z) to which a first battery pack (1), which is obtained by dividing a plurality of batteries connected in series, is connected, and a second measurement circuit (2z) to which a second battery pack (2), which is obtained by dividing a plurality of batteries connected in series, is connected; a second measurement circuit (2z) to which a second battery pack (2) obtained by dividing a plurality of batteries is connected; and an impedance calculation unit (15) that calculates the AC impedance of each of the plurality of batteries on the basis of the measured current value flowing through the first measurement circuit (1z) and the voltage value of each battery included in the first battery pack (1), and the measured current value flowing through the second measurement circuit (2z) and the voltage value of each battery included in the second battery pack (2). The first measurement circuit (1z) has a first switch, the second measurement circuit (2z) has a second switch, and the signal generation unit generates a control signal for turning on the first switch and the second switch in a mutually exclusive manner.

Description

Technical Field

[0001] This disclosure relates to a battery monitoring device and a battery monitoring method. Background Technology

[0002] In recent years, the application of rechargeable batteries has increased dramatically, including in environmentally friendly vehicles such as electric vehicles and in batteries used to ensure a stable supply of renewable energy. Due to their high energy density, lithium-ion batteries (LiB) are commonly used as rechargeable batteries. It is well known that lithium-ion batteries deteriorate rapidly due to overcharging, over-discharging, and overheating. In the worst-case scenario, they can even reach dangerous states such as smoking, fire, or explosion. Therefore, they are usually configured in a battery management system (BMS) and used under appropriate control.

[0003] In recent years, research has been conducted on improving battery control accuracy by measuring the AC impedance of batteries to detect battery degradation or internal temperature. For example, Patent Document 1 discloses a method that uses AC impedance to measure voltage and current while sweeping AC signals across each cell in a battery pack.

[0004] (Existing technical documents) (Patent Documents) Patent Document 1: International Publication No. 2020 / 003841 Summary of the Invention

[0005] The problem that the invention aims to solve However, in the method disclosed in Patent Document 1, there is a problem that the circuit used to measure the AC impedance of the battery will generate heat.

[0006] Therefore, this disclosure provides a battery monitoring device and a battery monitoring method that can suppress the heating of the circuit for measuring the AC impedance of a battery.

[0007] The means to solve the problem One embodiment of the battery monitoring device disclosed herein includes: a signal generation unit that generates control signals for controlling a first measurement circuit and a second measurement circuit, the first measurement circuit being connected to a first battery pack and the second measurement circuit being connected to a second battery pack, the first battery pack and the second battery pack being obtained by dividing a plurality of batteries connected in series; and an impedance calculation unit that calculates the AC impedance of each of the plurality of batteries based on a first current value flowing through the first measurement circuit and the voltage value of each battery included in the first battery pack, measured at different timings, and a second current value flowing through the second measurement circuit and the voltage value of each battery included in the second battery pack, the first measurement circuit having a first switch connected in series with the first battery pack, the second measurement circuit having a second switch connected in series with the second battery pack, and the signal generation unit generating the control signals for turning on the first switch and the second switch in a mutually exclusive manner.

[0008] In a battery monitoring method according to one embodiment of this disclosure, a control signal is generated to control a first measurement circuit and a second measurement circuit. The first measurement circuit is connected to a first battery pack, and the second measurement circuit is connected to a second battery pack. The first and second battery packs are obtained by dividing a plurality of batteries connected in series. Based on a first current value flowing through the first measurement circuit and the voltage value of each battery in the first battery pack, measured at different time intervals, and a second current value flowing through the second measurement circuit and the voltage value of each battery in the second battery pack, the AC impedance of each of the plurality of batteries is calculated. The first measurement circuit has a first switch connected in series with the first battery pack, and the second measurement circuit has a second switch connected in series with the second battery pack. In the generation of the control signal, a control signal is generated to turn on the first switch and the second switch in a mutually exclusive manner.

[0009] Invention Effects One aspect of this disclosure enables the development of a battery monitoring device that suppresses heating of the circuit used to measure the AC impedance of a battery. Attached Figure Description

[0010] Figure 1 This is a diagram showing the configuration of the battery monitoring system according to Embodiment 1.

[0011] Figure 2 It is a diagram showing the voltage waveform of the control signal pulse applied to the transistor involved in Embodiment 1.

[0012] Figure 3 This is a diagram showing the configuration of the battery monitoring system according to Embodiment 2.

[0013] Figure 4 This is a diagram showing the configuration of the battery monitoring system according to Embodiment 3.

[0014] Figure 5 This is a flowchart illustrating the fault diagnosis and correction operations in the battery monitoring system involved in each embodiment.

[0015] Figure 6 This is a diagram showing the configuration of a battery monitoring system as in a previous example.

[0016] Figure 7 This is a diagram showing the configuration of the battery monitoring system in the comparative example. Detailed Implementation

[0017] (How this disclosure came about) Before explaining this disclosure, please refer to Figure 6 and Figure 7 To explain how this disclosure came about. Figure 6 This is a diagram showing the structure of a battery monitoring system as in a previous example. Figure 7 This is a diagram showing the structure of the battery monitoring system in the comparative example.

[0018] exist Figure 6 and Figure 7 The image shows a battery monitoring system in a battery pack consisting of 18 batteries (1a-1i and 2a-2i) connected in series. Figure 6 In the battery monitoring system shown, the circuit for measuring the AC impedance of the battery includes a first load resistor 3, a first transistor 5, and a first shunt resistor 7. Furthermore, the integrated circuit for measuring impedance includes an impedance measurement integrated circuit 901, which comprises multiple voltage measurement units and impedance calculation units. In other words, Figure 6 The battery monitoring system has an integrated circuit. Furthermore, in Figure 7 In the battery monitoring system shown, the circuit for measuring the AC impedance of the first battery pack 1 includes a first load resistor 3, a first transistor 5, and a first shunt resistor 7. An impedance measurement integrated circuit 902, comprising multiple voltage measurement units and impedance calculation units, is also included as an impedance measurement integrated circuit. Furthermore, the circuit for measuring the complex impedance of the second battery pack 2 includes a second load resistor 4, a second transistor 6, and a second shunt resistor 8. Finally, an impedance measurement integrated circuit 903, comprising multiple voltage measurement units and impedance calculation units, is also included as an impedance measurement integrated circuit. In other words, Figure 7 The battery monitoring system has two integrated circuits.

[0019] As mentioned in the "Background Technology" section above, although lithium-ion batteries are widely used as secondary batteries, it is well known that lithium-ion batteries degrade more rapidly due to factors such as overcharging, over-discharging, and over-temperature. Therefore, they are usually assembled in a BMS for use under proper control.

[0020] In order to detect battery degradation, internal temperature, etc., and improve the accuracy of battery control, for example, Patent Document 1 proposes to use the AC impedance method to measure the voltage and current of the battery.

[0021] However, the impedance measurement circuit proposed in Patent Document 1, when measuring the impedance of multiple batteries configured as multiple series connections (for example, referring to...), Figure 6 The heat generated by the total voltage and impedance measurement current of multiple batteries will be generated on the first load resistor 3. Therefore, it is necessary to dissipate the heat generated during the measurement, such as by adding a fan or other heat dissipation function, or by connecting the first load resistor 3 in parallel to distribute the heat generated on the load resistor, which leads to an increase in circuit size.

[0022] In addition, if we consider Figure 7 The configuration shown, while reducing heat generation in the first load resistor 3 and the second load resistor 4, requires a corresponding number of impedance measurement circuit wiring harnesses to match the number of integrated circuits needed. Therefore, the circuit size increases with the number of batteries connected in series. In other words, in... Figure 7 In the comparative example shown, it is difficult to simultaneously achieve heat suppression and circuit size reduction.

[0023] Therefore, the inventors of this application have conducted in-depth research on battery monitoring devices and methods capable of suppressing heat generation in circuits used for measuring the AC impedance of batteries, and have created the battery monitoring devices and methods shown below. Furthermore, the inventors of this application have also created battery monitoring devices and methods capable of reducing the size of AC impedance measurement circuits for battery packs composed of many batteries connected in series.

[0024] The battery monitoring device according to the first aspect of this disclosure includes: a signal generation unit that generates control signals to control a first measurement circuit and a second measurement circuit, the first measurement circuit being connected to a first battery pack and the second measurement circuit being connected to a second battery pack, the first battery pack and the second battery pack being obtained by dividing a plurality of batteries connected in series; and an impedance calculation unit that calculates the AC impedance of each of the plurality of batteries based on a first current value flowing through the first measurement circuit and the voltage value of each battery included in the first battery pack, measured at different timings, and a second current value flowing through the second measurement circuit and the voltage value of each battery included in the second battery pack, the first measurement circuit having a first switch connected in series with the first battery pack, the second measurement circuit having a second switch connected in series with the second battery pack, and the signal generation unit generating the control signals for turning on the first switch and the second switch in a mutually exclusive manner.

[0025] Therefore, the timing of impedance measurements for the first and second battery packs can be made independent (different from each other), resulting in the dispersal of heating time and thus suppressing heating at the load resistor. Consequently, according to the battery monitoring device, heating of the circuit used to measure the AC impedance of the battery can be suppressed.

[0026] Furthermore, for example, the battery monitoring device according to the second aspect of this disclosure may be based on the battery monitoring device according to the first aspect of this disclosure, wherein the first measuring circuit has a first transistor connected to the first battery pack as the first switch, the second measuring circuit has a second transistor connected to the second battery pack as the second switch, and the control signal may also be a signal for causing the first transistor and the second transistor to operate in a time-division manner during mutually independent periods.

[0027] Therefore, by using the first transistor and the second transistor, the timing of impedance measurement can be easily made independent of each other.

[0028] Furthermore, for example, the battery monitoring device according to the third aspect of this disclosure may be based on the battery monitoring device according to the first or second aspect of this disclosure, wherein the first control signal output to the first transistor and the second control signal output to the second transistor are rectangular wave signals that can be controlled at any period, and the signal generation unit sets the duty cycle of the first control signal corresponding to the period of the first control signal, and sets the duty cycle of the second control signal corresponding to the period of the second control signal.

[0029] Therefore, when the frequency of the control signal is changed (e.g., by sweeping), the heat generation at the load resistor can be suppressed from changing with frequency. Additionally, for example, by setting the duty cycle to reduce heat generation, the heat generation itself can be reduced.

[0030] Furthermore, for example, the battery monitoring device involved in the fourth aspect of this disclosure may be based on the battery monitoring device involved in any one of the first to third aspects of this disclosure, wherein a portion of the wiring harness of the first measurement circuit and the second measurement circuit may also be shared.

[0031] This reduces the number of wires used to construct the first and second measurement circuits. Therefore, it is possible to balance heat suppression and circuit size reduction.

[0032] Furthermore, for example, the battery monitoring device according to the fifth aspect of this disclosure may be based on the battery monitoring device according to the fourth aspect of this disclosure, wherein the first measuring circuit has a first load resistor connected to the first battery pack for measuring the AC impedance and a first shunt resistor for measuring the current, and the second measuring circuit has a second load resistor connected to the second battery pack for measuring the AC impedance and a second shunt resistor for measuring the current. The common wiring harness may also be configured to connect the negative terminal of the first battery pack and the positive terminal of the second battery pack to the first load resistor and the second load resistor.

[0033] This reduces the number of wiring harnesses used to connect the negative terminal of the first battery pack and the positive terminal of the second battery pack to the first load resistor and the second load resistor.

[0034] Furthermore, for example, the battery monitoring device according to the sixth aspect of this disclosure may be based on the battery monitoring device according to the fourth aspect of this disclosure, wherein the first measuring circuit has: the first battery pack; and a first load resistor connected to the first battery pack for measuring the AC impedance and a first shunt resistor for measuring the current, and the second measuring circuit has: the second battery pack; and a second load resistor connected to the second battery pack for measuring the AC impedance and a second shunt resistor for measuring the current, wherein the first load resistor and the second load resistor may also be disposed on the common part of the wiring harness.

[0035] Therefore, since the load resistors of the first measurement circuit and the second measurement circuit can be shared, the circuit size can be further reduced.

[0036] Furthermore, for example, the battery monitoring device according to the seventh aspect of this disclosure may be based on the battery monitoring device according to the fifth or sixth aspect of this disclosure, and may also include an integrated circuit, which may include: a first current measuring unit for measuring the current flowing through the first shunt resistor; a first voltage measuring unit for measuring the voltage of each battery in the first battery pack; a first impedance measurement calculation unit for calculating the AC impedance of each battery in the first battery pack based on the current value measured by the first current measuring unit and the voltage value of each battery in the first battery pack measured by the first voltage measuring unit; a second current measuring unit for measuring the current flowing through the second shunt resistor; a second voltage measuring unit for measuring the voltage of each battery in the second battery pack; and a second impedance measurement calculation unit for calculating the AC impedance of each battery in the second battery pack based on the current value measured by the second current measuring unit and the voltage value of each battery in the second battery pack measured by the second voltage measuring unit.

[0037] Therefore, since the battery monitoring device can be implemented with a single integrated circuit that has all the functions, the circuit size can be reduced compared to the case where multiple integrated circuits are used.

[0038] Furthermore, for example, the battery monitoring device according to the eighth aspect of this disclosure may be based on the battery monitoring device according to any one of the fifth to seventh aspects of this disclosure, wherein the bottom battery of the first battery pack is connected to the top battery of the second battery pack, the positive terminal of the top battery in the first battery pack is connected to the first shunt resistor, the first shunt resistor is connected to the first transistor as the first switch, the negative terminal of the bottom battery in the second battery pack is connected to the second shunt resistor, and the second shunt resistor is connected to the second transistor as the second switch.

[0039] Therefore, since transistors are configured in both the first and second measurement circuits, it is easy to share a portion of the wiring harnesses of the first and second measurement circuits.

[0040] Furthermore, for example, the battery monitoring device according to the ninth aspect of this disclosure may be based on the battery monitoring device according to any one of the first to eighth aspects of this disclosure, wherein the plurality of batteries includes one or more batteries that are included in both the first battery pack and the second battery pack.

[0041] Therefore, by using one or more batteries with a common configuration, it is easy to detect faults in the measurement circuit.

[0042] Furthermore, for example, the battery monitoring device according to the 10th aspect of this disclosure may be based on the battery monitoring device according to any one of the 1st to 9th aspects of this disclosure, wherein the bottommost battery of the first battery pack is connected to the topmost battery of the second battery pack, and the battery monitoring device may also include a computing unit, which performs at least one of fault determination and AC impedance correction based on the AC impedance of the bottommost battery in the first battery pack and the AC impedance of the topmost battery in the second battery pack. The fault determination refers to determining the fault of the first measurement circuit and the second measurement circuit, and the AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

[0043] Therefore, since AC impedance can be used as a parameter to detect faults in the measurement circuit, the safety of the battery monitoring device can be improved.

[0044] Furthermore, for example, the battery monitoring device according to the 11th aspect of this disclosure may be based on the battery monitoring device according to any one of the 1st to 10th aspects of this disclosure, wherein the battery monitoring device comprises: a first calculation unit that estimates a first capacity retention rate of the first battery based on the AC impedance of any first battery included in the first battery pack, and estimates a second capacity retention rate of the second battery based on the AC impedance of any second battery included in the second battery pack; and a second calculation unit that, based on a third capacity retention rate of the first battery and a fourth capacity retention rate of the second battery estimated from parameters other than AC impedance, and the first capacity retention rate and the second capacity retention rate, performs at least one of fault determination and AC impedance correction, wherein fault determination refers to determining a fault in the first measurement circuit and the second measurement circuit, and AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

[0045] Therefore, since the state of health (SOH) can be used as a parameter to detect faults in the measurement circuit, the safety of the battery monitoring device can be improved.

[0046] Furthermore, for example, the battery monitoring device according to the 12th aspect of this disclosure may be based on the battery monitoring device according to any one of the 1st to 11th aspects of this disclosure, wherein the bottommost battery of the first battery pack is connected to the topmost battery of the second battery pack, and the battery monitoring device may also include: a temperature measuring unit that measures the temperature of the bottommost battery and the topmost battery based on the outputs of a first temperature sensor and a second temperature sensor, wherein the first temperature sensor is used to measure the temperature of the bottommost battery in the first battery pack, and the second temperature sensor is used to measure the temperature of the topmost battery in the second battery pack; and a battery state calculation unit that, based on the internal temperature of the bottommost battery estimated from the AC impedance of the bottommost battery in the first battery pack, and the respective temperatures of the topmost battery and the bottommost battery obtained by the temperature measuring unit, performs at least one of fault determination and AC impedance correction, wherein the fault determination refers to determining a fault in the first measurement circuit and the second measurement circuit, and the AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

[0047] Therefore, since temperature can be used as a parameter to detect faults in the measurement circuit, the safety of the battery monitoring device can be improved.

[0048] Furthermore, in the battery monitoring method according to the 13th aspect of this disclosure, a control signal is generated to control a first measurement circuit and a second measurement circuit. The first measurement circuit is connected to a first battery pack, and the second measurement circuit is connected to a second battery pack. The first battery pack and the second battery pack are obtained by dividing a plurality of batteries connected in series. Based on a first current value flowing through the first measurement circuit and the voltage value of each battery included in the first battery pack, measured at different time intervals, and a second current value flowing through the second measurement circuit and the voltage value of each battery included in the second battery pack, the AC impedance of each of the plurality of batteries is calculated. The first measurement circuit has a first switch connected in series with the first battery pack, and the second measurement circuit has a second switch connected in series with the second battery pack. In the generation of the control signal, a control signal is generated to turn on the first switch and the second switch in a mutually exclusive manner.

[0049] Therefore, it can produce the same effect as the battery monitoring device mentioned above.

[0050] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0051] Furthermore, each embodiment described below illustrates a specific example of this disclosure. The numerical values, shapes, materials, constituent elements, arrangement and connection methods of constituent elements, steps, and order of steps shown in the following embodiments are merely examples and are not intended to limit this disclosure. Additionally, constituent elements not described in the independent claims in the following embodiments will be described as arbitrary constituent elements.

[0052] Furthermore, the figures are not necessarily drawn strictly. In each figure, substantially identical components are assigned the same number, and repetitive descriptions are omitted or simplified.

[0053] In addition, "connection" refers to electrical connection, which includes not only the case where two circuit elements are directly connected, but also the case where two circuit elements are indirectly connected when other circuit elements are inserted between them.

[0054] Furthermore, in this specification, terms indicating relationships between elements such as the same, as well as numerical values ​​and ranges, do not mean only in a strict sense, but also include substantially equivalent ranges, such as those containing a difference of about a few percent (or about 10%).

[0055] In addition, in this specification, ordinal numbers such as "first" and "second" do not indicate the quantity or order of constituent elements unless otherwise specified, but are used to distinguish them in order to avoid confusion among similar constituent elements.

[0056] (Implementation Method 1) The following will refer to Figure 1 and Figure 2 The battery monitoring device involved in this embodiment will be described. Figure 1 This is a diagram showing the configuration of the battery monitoring system 301 according to this embodiment.

[0057] like Figure 1 As shown, the battery monitoring system 301 is a system for monitoring (or controlling) a battery pack consisting of secondary batteries such as lithium-ion batteries connected in series. In this embodiment, the battery monitoring system 301 is a system for monitoring the first battery pack 1 and the second battery pack 2.

[0058] The battery monitoring system 301 includes a battery monitoring device 201, which comprises: a first load resistor 3, a first transistor 5, and a first shunt resistor 7 connected in series with a first battery pack 1; a second load resistor 4, a second transistor 6, and a second shunt resistor 8 connected in series with a second battery pack 2; a first thermistor 19; a second thermistor 20; and an integrated circuit 101. The battery monitoring system 301 may further include battery packs (first battery pack 1 and second battery pack 2) as the objects of monitoring.

[0059] In this embodiment, the battery pack is composed of 18 batteries connected in series, namely batteries 1a to 1i and batteries 2a to 2i. The first battery pack 1 contains more than one battery. Figure 1 The example includes nine batteries 1a to 1i connected in series; the second battery pack 2 contains more than one battery. Figure 1 The example includes nine batteries 2a to 2i connected in series. The first battery pack 1 and the second battery pack 2 are connected in series to form a battery pack. Each of the batteries 1a to 1i and 2a to 2i is configured as a rechargeable secondary battery, such as a lithium-ion battery.

[0060] Furthermore, the number of batteries contained in the first battery pack 1 and the second battery pack 2 is not particularly limited; for example, they may contain different numbers of batteries. Similarly, the number of batteries in the battery monitoring system 301 is not particularly limited, as long as there are two or more. Additionally, batteries 1a to 1i and batteries 2a to 2i may be referred to as battery cells below.

[0061] In addition, as will be described later, the battery monitoring system 301 is configured to measure the voltage and current of the first battery pack 1 and the second battery pack 2 in a time-sharing manner.

[0062] The first measuring circuit 1z is a circuit used to measure the AC impedance of each battery in the first battery pack 1. It has a first load resistor 3, a first transistor 5, and a first shunt resistor 7 connected in series with the first battery pack 1. When the first transistor 5 is turned on, a closed circuit is formed by the first load resistor 3, the first transistor 5, the first shunt resistor 7, and the first battery pack 1.

[0063] The first load resistor 3 is connected to the negative terminal (negative voltage terminal of battery 1i) of the first battery pack 1 and is a resistor used to allow current to flow for measuring the impedance of each battery in the first battery pack 1.

[0064] The first shunt resistor 7 is connected to the positive terminal (positive voltage terminal of battery 1a) of the first battery pack 1 and is a current measuring resistor used to measure the current flowing through the first measuring circuit 1z, which includes the first battery pack 1. Its two ends are connected to the first current measuring unit 9. Specifically, the first shunt resistor 7 is used to measure the current (pulse current) discharging from the first battery pack 1 by turning on the first transistor 5.

[0065] The first transistor 5 is connected between the first load resistor 3 and the first shunt resistor 7, and is switched on and off by a control signal generated by the first current-driven waveform generation unit 11. The first transistor 5 is controlled by the control signal to switch at the frequency of impedance measurement. The first transistor 5 is a p-type transistor, but is not limited to this. The first transistor 5 is an example of a switch (first switch).

[0066] In the first measurement circuit 1z configured as such, the first load resistor 3 generates heat due to the total voltage of only batteries 1a to 1i among batteries 1a to 1i and 2a to 2i. Since the voltage applied to the first load resistor 3 can be made relatively... Figure 6 The situation is even lower, thus reducing the heat generated in the first load resistor 3.

[0067] Furthermore, the arrangement order of the first load resistor 3, the first transistor 5, and the first shunt resistor 7 is not limited to... Figure 1 The sequence shown can be achieved simply by connecting the positive terminal of the first battery pack 1 in series with the negative terminal of the first battery pack 1.

[0068] The second measuring circuit 2z is used to measure the AC impedance of each battery in the second battery pack 2. It has a second load resistor 4, a second transistor 6, and a second shunt resistor 8 connected in series with the second battery pack 2. When the second transistor 6 is turned on, a closed circuit is formed by the second load resistor 4, the second transistor 6, the second shunt resistor 8, and the second battery pack 2.

[0069] The second load resistor 4 is connected to the positive terminal (positive voltage terminal of battery 2a) of the second battery pack 2 and is a resistor used to allow current to flow for measuring the impedance of each battery in the second battery pack 2.

[0070] The second shunt resistor 8 is connected to the negative terminal (negative voltage terminal of battery 2i) of the second battery pack 2. It is a current measuring resistor used to measure the current flowing through the second measuring circuit 2z, which includes the second battery pack 2. Its two ends are connected to the second current measuring unit 10. Specifically, the second shunt resistor 8 is used to measure the current (pulse current) discharging from the second battery pack 2 by turning on the second transistor 6.

[0071] The second transistor 6 is connected between the second load resistor 4 and the second shunt resistor 8, and is switched on and off by a control signal generated by the second current drive waveform generation unit 12. The second transistor 6 is controlled by the control signal to switch at the frequency of impedance measurement. The second transistor 6 is an n-type transistor, but is not limited to this. The second transistor 6 is an example of a switch (second switch).

[0072] In the second measuring circuit 2z configured as described above, the second load resistor 4 generates heat due to the total voltage of only batteries 2a to 2i out of batteries 1a to 1i and 2a to 2i. This is because the voltage applied to the second load resistor 4 can be made relatively smaller than... Figure 6 The situation is even lower, thus reducing the heat generated in the second load resistor 4.

[0073] Furthermore, the arrangement order of the second load resistor 4, the second transistor 6, and the second shunt resistor 8 is not limited to... Figure 1 The sequence shown can be achieved simply by connecting the positive terminal of the second battery pack 2 in series with the negative terminal of the second battery pack 2.

[0074] In addition, the first switch and the second switch are not limited to semiconductor switches, but can also be other switches besides semiconductor switches.

[0075] Here, a portion of the wiring (e.g., a portion of a wiring harness) of both the first measurement circuit 1z and the second measurement circuit 2z is shared. The battery monitoring system 301 includes a common wiring harness 30 shared by the first measurement circuit 1z and the second measurement circuit 2z. The common wiring harness 30 is configured to connect the negative terminal of the first battery pack 1 and the positive terminal of the second battery pack 2 to the first load resistor 3 and the second load resistor 4. This allows for a reduction in the size of the measurement circuit for a battery pack consisting of multiple batteries using a single integrated circuit 101. Furthermore, providing a common wiring harness 30 is not mandatory; the first measurement circuit 1z and the second measurement circuit 2z can also be formed with different wiring configurations.

[0076] The first thermistor 19 is disposed near the first battery pack 1 and is a temperature sensor used to measure the temperature of the first battery pack 1 (the temperature around the first battery pack 1) during the measurement of the impedance of the first battery pack 1. In this embodiment, the first thermistor 19 is disposed near the battery 1i (the bottommost cell) in the first battery pack 1 that is closest to the second battery pack 2, and is used to measure the temperature around the battery 1i. Alternatively, the first thermistor 19 may also be disposed at the voltage terminal of the bottommost cell of the first battery pack 1.

[0077] The second thermistor 20 is positioned near the second battery pack 2 and is a temperature sensor used to measure the temperature of the second battery pack 2 (the temperature around the second battery pack 2) during the measurement of its impedance. In this embodiment, the second thermistor 20 is positioned near the battery 2a (the uppermost cell) closest to the first battery pack 1 in the second battery pack 2, and is used to measure the temperature around that battery 2a. Alternatively, the second thermistor 20 may also be positioned at the voltage terminal of the uppermost cell in the second battery pack 2.

[0078] Since batteries 1i and 2a are adjacent batteries, the first thermistor 19 and the second thermistor 20 will be positioned close to each other. Therefore, assuming that the components of batteries 1i and 2a or the first measurement circuit 1z and the second measurement circuit 2z are functioning normally, the temperature measured by the first thermistor 19 and the temperature measured by the second thermistor 20 will be similar.

[0079] In addition, the temperature sensor provided by the battery monitoring system 301 is not limited to a thermistor; for example, it can also be a temperature sensor using other components such as a thermocouple.

[0080] Integrated circuit 101 includes a first current measurement unit 9, a second current measurement unit 10, a first current-driven waveform generation unit 11, a second current-driven waveform generation unit 12, a voltage measurement unit 13, a SOC (State of Charge) calculation unit 14, an impedance calculation unit 15, a battery state calculation unit 16, a temperature measurement unit 17, and a storage unit 18. Integrated circuit 101 includes a processor and a memory. The memory, for example, is ROM (Read Only Memory) or RAM (Random Access Memory), and is capable of storing programs executed by the processor. The first current measurement unit 9, the second current measurement unit 10, the first current-driven waveform generation unit 11, the second current-driven waveform generation unit 12, the voltage measurement unit 13, the SOC calculation unit 14, the impedance calculation unit 15, the battery state calculation unit 16, and the temperature measurement unit 17 are implemented by a processor that executes the program stored in the memory. Furthermore, for example, each of the above functions can be implemented by a single integrated circuit 101.

[0081] The first current measuring unit 9 measures the current flowing through the first measuring circuit 1z, which includes the first battery pack 1. The first current measuring unit 9 may also include an ADC (Analog-to-Digital Converter) unit that converts an analog signal value equivalent to the current of the first battery pack 1 into a digital signal value; and an arithmetic unit that performs calculations on the digital signal value output by the ADC unit to calculate the current value. Furthermore, while the first current measuring unit 9 is a resistance-detection type current sensor using the first shunt resistor 7, it may also be a magnetic field-detection type current sensor.

[0082] The second current measuring unit 10 measures the current flowing through the second measuring circuit 2z, which includes the second battery pack 2. The second current measuring unit 10 may also include an ADC unit that converts an analog signal value equivalent to the current of the second battery pack 2 into a digital signal value; and an arithmetic unit that performs calculations on the digital signal value output by the ADC unit to calculate the current value. Furthermore, although the second current measuring unit 10 is a resistance-detection type current sensor using the second shunt resistor 8, it may also be a magnetic field-detection type current sensor.

[0083] The first current-driven waveform generation unit 11 generates a control signal for controlling the first transistor 5 to turn on and off, and outputs it to the first transistor 5. This control signal is, for example, a rectangular wave signal that can be controlled at any period, and is input to the gate electrode of the first transistor 5. Alternatively, this control signal can be a control signal having multiple frequency components.

[0084] The second current-driven waveform generation unit 12 generates a control signal for controlling the second transistor 6 to turn on and off, and outputs it to the second transistor 6. This control signal is, for example, a rectangular wave signal that can be controlled at any period, and is input to the gate electrode of the second transistor 6. Alternatively, this control signal can be a control signal having multiple frequency components. These multiple frequency components can, for example, be the same as the multiple frequency components of the control signal generated by the first current-driven waveform generation unit 11.

[0085] Furthermore, the first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 generate control signals that turn on only one of the first transistor 5 and the second transistor 6. These control signals are used to cause the first transistor and the second transistor to operate in a time-division multiplexing manner during mutually independent periods. In other words, the first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 generate control signals to turn on the first transistor 5 and the second transistor 6 in a mutually exclusive manner. Thus, through the control signals, the periods during which the first transistor 5 is turned on and the periods during which the second transistor 6 is turned on are controlled to be non-overlapping in time.

[0086] Therefore, the measurement of current and voltage of the first battery pack 1 and the measurement of current and voltage of the second battery pack 2 can be performed in a time-division manner at different times. Thus, by controlling the on and off of the first transistor 5 and the second transistor 6 in a time-division manner respectively, the timing of the impedance measurements of the first battery pack 1 and the second battery pack 2 can be made independent (different from each other), resulting in the heat generation time being dispersed, thereby suppressing heat generation at the load resistor. Furthermore, the first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 are examples of signal generation units.

[0087] Furthermore, the period during which the first transistor 5 is turned on and the period during which the second transistor 6 is turned on are not limited to not overlapping at all in time; they may also overlap only in part.

[0088] Figure 2 This is a diagram showing the voltage waveform of the control signal pulse applied to the transistor involved in this embodiment. Figure 2 The example shows the voltage waveforms of four control signals (control signals w1 to w4) generated by the first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12.

[0089] The control signal w1 shows the voltage waveform at a frequency of 2f and a duty cycle of 50%.

[0090] The control signal w2 shows the voltage waveform at a frequency of f and a duty cycle of 50%.

[0091] If the first transistor 5 is turned on by the control signal w1, a pulse current with a frequency of 2f is emitted from the first battery pack 1 during the on-time, thus causing the first load resistor 3 to heat up. When the control signal is switched from control signal w1 to control signal w2, that is, when the frequency of the control signal is changed from 2f to f and the duty cycle is maintained at 50%, the heat generated by the first load resistor 3 becomes twice.

[0092] From the perspective of suppressing differences in heat generation caused by variations in control signal frequency, the duty cycle can be adjusted according to the frequency. Therefore, even if the frequency of the control signal is changed, the heat generation can be kept nearly constant while maintaining a constant conduction period. For example, when changing the control signal frequency from 2f to f, a control signal w3 that changes the duty cycle from 50% to 25% can be used. Furthermore, from the perspective of further suppressing heat generation, a control signal w4 that further sets the duty cycle to 50% within the pulse of the conduction period can also be used.

[0093] The first current-driven waveform generation unit 11 sets the duty cycle of the first control signal, which corresponds to the period of the first control signal, and the second current-driven waveform generation unit 12 sets the duty cycle of the second control signal, which corresponds to the period of the second control signal. The first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 set the duty cycle of the control signal with a frequency of f to 2f, such that the difference between the heat generated at a reference frequency set within a specified frequency band (e.g., f to 2f) and the heat generated at other frequencies between f to 2f is below a predetermined value. The first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 can also be set such that: the lower the frequency, the smaller the duty cycle; and the higher the frequency, the larger the duty cycle. For example, a table corresponding to frequency and duty cycle can be stored in the storage unit 18, and the first current-driven waveform generation unit 11 and the second current-driven waveform generation unit 12 can also use this table to switch the duty cycle according to frequency.

[0094] The reference frequency can also be a frequency in the frequency band that is higher than a predetermined value (e.g., the highest). In the case where the frequency band is between f and 2f, the reference frequency can also be frequency 2f. For example, the reference frequency can also be a frequency in the frequency band where the heat generation is below a specified value (e.g., the minimum) when the duty cycle is the same.

[0095] Alternatively, for example, during the period when a control signal is applied to the first transistor 5, a control signal (a constant voltage control signal) is applied to the second transistor 6 to turn it off.

[0096] Refer again Figure 1 The voltage measuring unit 13 is provided one-to-one with each battery and is used to measure the voltage of the connected battery. The voltage measuring unit 13 may also include: an ADC unit that converts an analog signal value corresponding to the battery voltage into a digital signal value; and an arithmetic unit that performs arithmetic processing on the digital signal value output by the ADC unit to calculate the voltage value.

[0097] The SOC calculation unit 14 measures the SOC of the battery pack. For example, the SOC calculation unit 14 can also acquire the current and voltage of the battery pack or each battery 1a to 2i constituting the battery pack, and calculate the SOC by coulomb counting or by estimating based on the SOC-OCV (Open Circuit Voltage) curve.

[0098] The impedance calculation unit 15 calculates the AC impedance of each of the multiple batteries 1a to 1i and batteries 2a to 2i based on the AC voltage and AC current obtained by measuring the first battery pack 1 and the second battery pack 2. The impedance calculation unit 15 measures the current I1 flowing through the first shunt resistor 7, obtained by applying a control signal with multiple frequency components to the control terminal of the first transistor 5, and the voltage Vn1 of each battery in the first battery pack 1. Furthermore, the impedance calculation unit 15 also measures the current I2 flowing through the second shunt resistor 8, obtained by applying a control signal with multiple frequency components to the control terminal of the second transistor 6, and the voltage Vn2 of each battery in the second battery pack 2.

[0099] Then, the impedance calculation unit 15 converts the measured currents I1 and I2 into complex currents, and the measured voltages Vn1 and Vn2 into complex voltages. Afterwards, the impedance calculation unit 15 averages both the complex currents and complex voltages. The impedance calculation unit 15 calculates the AC impedance of each battery by dividing the averaged complex voltage by the averaged complex current. Each AC impedance is a complex number (complex impedance), having a real component Re and an imaginary component Im. Additionally, the AC impedance will sometimes be simply referred to as impedance in the following text.

[0100] Based on the calculation results of the impedance calculation unit 15, the battery state calculation unit 16 estimates at least one of the capacity retention rate (SOH: State of Health) and internal temperature, which represent the battery's deterioration state.

[0101] Having obtained a first correspondence between AC impedance and battery full charge capacity in advance, the battery state calculation unit 16 can also estimate the current battery full charge capacity based on this first correspondence and the current AC impedance, and calculate SOH (%) by dividing the estimated current full charge capacity by the initial full charge capacity and then multiplying by 100. The initial full charge capacity and the first correspondence can also be stored in the storage unit 18. Alternatively, the first correspondence can be, for example, a table corresponding to AC impedance and battery full charge capacity.

[0102] Having obtained a second correspondence between AC impedance and battery internal temperature in advance, the battery state calculation unit 16 can also estimate the current battery internal temperature based on this second correspondence and the current AC impedance. The second correspondence can also be stored in the storage unit 18. Alternatively, the second correspondence can be, for example, a table corresponding to AC impedance and battery internal temperature.

[0103] Furthermore, the methods for estimating SOH and internal temperature are not limited to those described above; any known method may also be used.

[0104] The temperature measuring unit 17 measures the temperature of the battery pack. The temperature measuring unit 17 is connected to a first thermistor 19 near the first battery pack 1 and a second thermistor 20 near the second battery pack 2, and measures the temperature around the first thermistor 19 and the second thermistor 20. In this embodiment, the temperature measuring unit 17 measures the temperature near battery 1i and near battery 2a.

[0105] The storage unit 18 is a storage device used to store various information and programs for estimating battery status. The storage unit 18 is implemented, for example, by an HDD (Hard Disk Drive) or a semiconductor memory.

[0106] Alternatively, integrated circuit 101 may also include a diagnostic correction unit for fault diagnosis and impedance correction (e.g., described later). Figure 3 Diagnostic correction unit 21 shown).

[0107] (Implementation Method 2) Reference Figure 3 The structure of the battery monitoring device involved in this embodiment will be described. Figure 3 This diagram illustrates the configuration of the battery monitoring system 301 according to this embodiment. The main difference between the battery monitoring system 301 according to this embodiment and the battery monitoring system 301 according to Embodiment 1 is that the load resistor (third load resistor 22) is a common resistor in both the first measurement circuit 1z and the second measurement circuit 2z. The differences from Embodiment 1 will be emphasized below; descriptions of contents that are the same as or similar to Embodiment 1 will be omitted or simplified. Furthermore, for convenience, structures that are the same as or similar to Embodiment 1 will be described using the designations of Embodiment 1.

[0108] like Figure 3 As shown, the battery monitoring system 301 has a third load resistor 22 to replace Figure 1 The first load resistor 3 and the second load resistor 4 are shown, and a diagnostic calibration unit 21 is also provided.

[0109] The third load resistor 22 is disposed on the common wiring harness 30. One end of the third load resistor 22 is connected to the negative terminal of the first battery pack 1 and the positive terminal of the second battery pack 2, and the other end is connected to the first transistor 5 and the second transistor 6. As a result, the number of load resistors can be reduced, and thus the size of the measurement circuit can be reduced.

[0110] The diagnostic calibration unit 21 diagnoses (determines) whether a fault has occurred in the measurement circuit (e.g., components of the measurement circuit) based on AC impedance, and corrects the impedance accordingly. Regarding the diagnostic calibration unit 21, please refer to... Figure 5 This will be explained later.

[0111] Furthermore, although the number of batteries in the first battery pack 1 is the same as the number of batteries in the second battery pack 2, they can be different as long as the measurement accuracy is within the range that meets the desired accuracy.

[0112] (Implementation Method 3) Reference Figure 4 The configuration of the battery monitoring device involved in this embodiment will be described. Figure 4 This diagram illustrates the configuration of the battery monitoring system 301 according to this embodiment. The battery monitoring system 301 according to this embodiment differs from the battery monitoring system 301 according to Embodiment 1 in that the battery 12a is respectively included in the first battery pack 1 and the second battery pack 2. The differences from Embodiment 1 will be emphasized below, while descriptions of contents that are the same as or similar to Embodiment 1 will be omitted or simplified. Furthermore, for convenience, structures that are the same as or similar to Embodiment 1 will be described using the designations of Embodiment 1.

[0113] like Figure 4 As shown, in the battery monitoring system 301 of this embodiment, the lowest cell of the first battery pack 1 and the highest cell of the second battery pack 2 are the same cell. A first load resistor 3 is connected to the negative terminal of this same cell, and a second load resistor 4 is connected to the positive terminal of this same cell. The first battery pack 1 includes batteries 1a to 1h and a common battery 12a, thus comprising 9 batteries. The second battery pack 2 includes batteries 2a to 2i and the common battery 12a, thus comprising 10 batteries. The number of batteries is not limited to this; for example, the first battery pack 1 and the second battery pack 2 can have the same number of batteries.

[0114] Battery 12a has its voltage measured when measuring the first battery pack 1 and when measuring the second battery pack 2. The voltage measurement result (voltage value) of battery 12a when measuring the first battery pack 1 should be the same as the voltage measurement result (voltage value) of battery 12a when measuring the second battery pack 2. By noting the difference between the two voltage values, it can be determined whether any component in the measurement circuit (e.g., at least one of the first load resistor 3, the second load resistor 4, the first transistor 5, the second transistor 6, the first shunt resistor 7, and the second shunt resistor 8) has malfunctioned. That is, the battery monitoring system 301 according to this embodiment can perform fault diagnosis of the measurement circuit.

[0115] Alternatively, this determination can be made using, for example, the current voltage value and past voltage value of battery 12a in the first battery pack 1 or the second battery pack 2. That is, it can also be determined whether battery 12a is experiencing calendar aging.

[0116] The first thermistor 19 is positioned near the commonly included battery 12a.

[0117] In addition, the number of batteries contained in the first battery pack 1 and the second battery pack 2 is not limited to one, but can also be multiple.

[0118] (Work example) Next, refer to Figure 5 The work performed by the battery monitoring system 301 described in the above embodiments regarding fault diagnosis and correction will be explained. Figure 5 A flowchart illustrating the fault diagnosis and correction process (battery monitoring method) in the battery monitoring system 301 according to each embodiment is provided.

[0119] like Figure 5 As shown, firstly, the battery monitoring device 201 controls the lower EIS (Electro-chemical Impedance Spectroscopy) measurement circuit (second measurement circuit 2z) to measure the AC voltage and AC current of the lower battery pack (second battery pack 2), and also measures the temperature of the second thermistor (S1). The second thermistor temperature is the temperature measured using the second thermistor 20. The battery monitoring device 201 measures the AC voltage and AC current of the second battery pack 2 by setting the first transistor 5 to cut off and the second transistor 6 to turn on. Here, setting the second transistor 6 to turn on means using a... Figure 2 The control signal shown is used to switch the second transistor 6 at the frequency of impedance measurement.

[0120] Next, after step S1, the battery monitoring device 201 controls the upper EIS measurement circuit (first measurement circuit 1z) to measure the AC voltage and AC current of the upper battery pack (first battery pack 1), and measures the temperature of the first thermistor (S2). The first thermistor temperature is the temperature measured using the first thermistor 19. The battery monitoring device 201 measures the AC voltage and AC current of the first battery pack 1 by setting the first transistor 5 to conduct and the second transistor 6 to cut off.

[0121] Thus, the measurements of the first measurement circuit 1z and the second measurement circuit 2z are performed at different times in a time-division manner.

[0122] Next, the impedance calculation unit 15 uses the measured AC voltage and AC current to calculate the impedance (AC impedance) (S3).

[0123] Next, the battery state calculation unit 16 estimates the first capacity retention rate and internal temperature based on the impedance calculated by the impedance calculation unit 15 (S4).

[0124] Next, the battery state calculation unit 16 stores the measurement results and the estimated results in the storage unit 18 (S5). Thus, the storage unit 18 stores the measurement values ​​obtained in steps S1 and S2 and the estimated values ​​estimated in step S4.

[0125] Next, the battery state calculation unit 16 uses time-sampled current and voltage data to estimate the second capacity retention rate (S6). Under the condition of constant frequency, the battery state calculation unit 16 estimates the second capacity retention rate based on the time response of current and voltage during battery discharge.

[0126] Furthermore, in the time sampling, the voltage measurement unit 13 is used to sample the voltage of each cell in the first battery pack 1 and the second battery pack 2 over time, the first current measurement unit 9 is used to sample the current over time, and the second current measurement unit 10 is used to sample the current over time. In addition, the measurements (time sampling) of the first measurement circuit 1z and the second measurement circuit 2z can also be performed at different times in a time-division manner.

[0127] Next, the battery state calculation unit 16 determines whether the difference between the values ​​(e.g., estimated values) of adjacent or common cells is below a threshold (S7). The values ​​of adjacent or common cells can be the measured impedance itself, or values ​​representing battery state such as capacity retention rate and internal temperature. The following describes an example of a value representing battery state.

[0128] For example, in Figure 1 or Figure 3 In the configuration shown, the battery state calculation unit 16 determines whether the difference in capacity retention rate or internal temperature between adjacent batteries (e.g., batteries 1i and 2a) is below a threshold. If capacity retention rate is used, the battery state calculation unit 16 performs at least one of the following operations: comparing the first capacity retention rate of battery 1i estimated in step S4 with the first capacity retention rate of battery 2a; and comparing the second capacity retention rate of battery 1i estimated in step S6 with the second capacity retention rate of battery 2a, thereby determining whether the difference in capacity retention rate is below a threshold.

[0129] Additionally, for example in Figure 4 In the configuration shown, the battery state calculation unit 16 determines whether the difference between the capacity retention rate or the internal temperature of the common cell (e.g., battery 12a) is below a threshold. If the capacity retention rate is used, the battery state calculation unit 16 performs at least one of the following operations: comparing the first capacity retention rate of battery 12a measured by the first measurement circuit 1z with the first capacity retention rate of battery 12a measured by the second measurement circuit 2z; and comparing the second capacity retention rate of battery 12a measured by the first measurement circuit 1z with the second capacity retention rate of battery 12a measured by the second measurement circuit 2z, thereby determining whether the difference in capacity retention rates is below a threshold.

[0130] When any component in the first measurement circuit 1z or the second measurement circuit 2z malfunctions, the difference in step S7 will exceed the threshold. At this point, while it is possible to determine whether a fault exists, it is impossible to pinpoint exactly which component of the measurement circuit is faulty. The threshold is preset and stored in the storage unit 18.

[0131] Alternatively, the determination in step S7 can be performed, for example, by determining whether the difference between the first capacity retention rate of the battery (e.g., battery 1i in the first measurement circuit 1z) estimated in step S4 and the second capacity retention rate of the battery estimated in step S6 is below a threshold. In this case, the determination is performed in both the first measurement circuit 1z and the second measurement circuit 2z.

[0132] Next, when the difference between the values ​​is not below the threshold, that is, when the difference between the two estimated values ​​is greater than the threshold (S7 is "No"), since there is a possibility that any component of the measurement circuit has failed, the diagnostic correction unit 21 reads a reference value of the value from the storage unit 18 and compares it to determine the faulty circuit (S8). In order to determine which component of the first measurement circuit 1z and the second measurement circuit 2z has failed, the diagnostic correction unit 21 reads a reference value of the capacity retention rate as an example of the value from the storage unit 18, and based on the reference value and the capacity retention rate of the adjacent batteries, for example, determines the measurement circuit containing the battery with a large difference from the reference value as the faulty circuit.

[0133] Next, the diagnostic calibration unit 21 notifies the user of a fault (S9). The diagnostic calibration unit 21 sends information indicating the identified faulty circuit to the user's (e.g., the battery pack manager's) terminal device.

[0134] Furthermore, when the difference between the values ​​is below a threshold, i.e., when the difference between the two estimated values ​​is close (S7 is "Yes"), the diagnostic correction unit 21 further determines whether it is a common cell structure (S10). A common cell structure refers to a structure such as... Figure 4 As shown, the two measurement circuits have a common cell (battery 12a) structure. Information indicating whether it is a common cell structure can also be stored in the storage unit 18, for example. Furthermore, a difference in values ​​below a threshold indicates that the measurement circuit has not malfunctioned.

[0135] Next, when the diagnostic calibration unit 21 determines that it is a common cell structure (S10 is "yes"), it further reads a reference value from the storage unit 18 and compares it to determine whether it is below a threshold (S11). The diagnostic calibration unit 21 will then compare the common cell (in...) Figure 4In the example, the capacity retention rate or internal temperature of battery 12a) is compared with its reference value, and it is determined whether the difference is below a threshold. The threshold here can be the same as the threshold in step S7, or they can be different from each other.

[0136] When the diagnostic correction unit 21 determines that the difference is below the threshold in the common cell structure (S11 is "yes"), or determines that it is not a common cell structure (S10 is "no"), the process ends.

[0137] Furthermore, when the diagnostic correction unit 21 determines that the difference is not below the threshold in the common cell structure, that is, when there is a difference greater than the threshold between the estimated value and the reference value (S11 is "No"), the impedance calculation is corrected based on the reference value (S12). The diagnostic correction unit 21 determines that the impedance measurement accuracy is reduced due to external factors (such as the influence of the magnetic field of the external circuit), and corrects the impedance calculated in step S3. The correction here means making the impedance calculated in step S3 closer to the true value based on the reference value.

[0138] The diagnostic correction unit 21 corrects the impedance stored in the storage unit 18 based on the reference value and stores the corrected impedance in the storage unit 18. The diagnostic correction unit 21 can replace the impedance calculated in step S3 with the reference value, or it can replace it with a statistical value of the impedance obtained from multiple past measurements, or it can multiply the coefficient based on the reference value with the impedance calculated in step S3. Although the statistical value is the average value, it can also be, for example, the median.

[0139] (Other implementation methods) The foregoing has described battery monitoring devices and the like in one or more ways based on various embodiments, but this disclosure is not limited to these embodiments. Various modifications to these embodiments that can be conceived by those skilled in the art without departing from the spirit of this disclosure, as well as forms constructed by combining the constituent elements of different embodiments, can be included in this disclosure.

[0140] For example, the battery monitoring device 201 and battery monitoring system 301 disclosed herein can be used as battery monitoring devices and BMS for monitoring batteries such as battery packs formed by connecting lithium-ion battery cells in series. In particular, the battery monitoring device 201 and battery monitoring system 301, as small battery monitoring devices capable of measuring battery impedance, can be used, for example, as battery monitoring devices for monitoring environmentally friendly vehicles, including electric vehicles, and batteries used to stably supply renewable energy.

[0141] Furthermore, while the above embodiments illustrate examples of dividing multiple batteries into two battery packs, the number of divisions is not limited to two; it can also be three or more. In this case, the impedance measurements of the three or more battery packs are performed at different timings.

[0142] Furthermore, in the above embodiments, each component can be constructed by dedicated hardware or implemented by executing software programs suitable for each component. Each component can also be implemented by a program execution unit such as a CPU or processor reading and executing software programs recorded on a recording medium such as a hard disk or semiconductor memory.

[0143] Furthermore, the execution order of the steps in the flowchart is merely an example for illustrating this disclosure, and other orders may also be used. Additionally, some of the above steps may be executed simultaneously (in parallel) with other steps, or some of the above steps may not be executed at all.

[0144] Furthermore, the functional module division in the block diagram is just one example. Multiple functional modules can also be implemented as a single module, or a single functional module can be divided into multiple modules, or some functions can be moved to other functional modules. Additionally, the functions of multiple functional modules with similar capabilities can be processed in parallel or time-sharing manner by a single piece of hardware or software.

[0145] Furthermore, the battery monitoring device 201 described in the above embodiments can be implemented as a single device or by multiple devices. When the battery monitoring device 201 is implemented by multiple devices, the constituent elements of the battery monitoring device 201 can be distributed among the multiple devices in any manner. When the battery monitoring device 201 is implemented by multiple devices, the communication method between the multiple devices is not particularly limited; it can be wireless communication or wired communication. Additionally, wireless and wired communication can be combined between the devices.

[0146] Furthermore, the constituent elements described in the above embodiments can be implemented as software, typically as an integrated circuit LSI. These constituent elements can be individually chip-based, or a portion or all of them can be chip-based. Although referred to as LSI here, it may also be called IC, system LSI, super LSI, or very large-scale LSI, depending on the level of integration. Moreover, the method of integrated circuit implementation is not limited to LSI; it can also be implemented using dedicated circuits (general-purpose circuits that execute dedicated programs) or general-purpose processors. FPGAs (Field Programmable Gate Arrays) that are programmable after LSI manufacturing can also be used, or reconfigurable processors capable of reconfiguring the connections or settings of the circuit units within the LSI can be used. Furthermore, if integrated circuit implementation technologies that replace LSIs emerge with advancements in semiconductor technology or other derived technologies, these technologies can certainly be used to integrate the constituent elements.

[0147] A system LSI is a multifunctional LSI that integrates multiple processing units onto a single chip. Specifically, it is a computer system comprising a microprocessor, ROM, RAM, etc. The ROM stores the computer program. The microprocessor executes the computer program, thus enabling the system LSI to perform its functions.

[0148] Alternatively, another aspect of this disclosure may be that the computer executes the executable contained in [the present disclosure]. Figure 5 The computer program for each characteristic step in the battery monitoring method shown.

[0149] Alternatively, for example, the program can also be a program for causing a computer to execute. One embodiment of this disclosure can also be a computer-readable, non-transitory recording medium on which the program is recorded. For example, the program can be recorded on the recording medium and distributed or circulated. For example, the distributed program can be installed in a device having other processors, and the processor can execute the program, thereby enabling the device to perform the aforementioned processes.

[0150] Industrial availability This disclosure includes a battery monitoring device for monitoring batteries such as battery packs.

[0151] Explanation of reference numerals in the attached figures 1. First battery pack 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, 1i, 2a, 2b, 2c, 2d, 2e, 2f, 2g, 2h, 2i, 12a batteries 1z First Measurement Circuit 2 Second battery pack 2z Second Measurement Circuit 3 First load resistor 4 Second load resistor 5 First transistor 6 Second transistor 7 First shunt resistor 8 Second shunt resistor 9 First Current Measurement Section 10 Second Current Measurement Section 11 First Current-Driven Waveform Generation Unit 12 Second Current Drive Waveform Generation Unit 13 Voltage Measurement Section 14 SOC Computing Unit 15 Impedance Calculation Section 16 Battery Status Calculation Unit 17 Temperature Measurement Department 18 Storage Department 19 First thermistor (first temperature sensor) 20 Second thermistor (second temperature sensor) 21. Diagnostic and Correction Department 22 Third load resistor 30 Common wiring harness 101 Integrated Circuits 201 Battery Monitoring Device 301 Battery Monitoring System 901, 902, 903 Impedance Measurement Integrated Circuits w1, w2, w3, w4 are control signals.

Claims

1. A battery monitoring device, The battery monitoring device includes: A signal generation unit generates control signals to control a first measurement circuit and a second measurement circuit. The first measurement circuit is connected to a first battery pack, and the second measurement circuit is connected to a second battery pack. The first and second battery packs are obtained by dividing multiple batteries connected in series. The impedance calculation unit calculates the AC impedance of each of the plurality of batteries based on a first current value flowing through the first measurement circuit and the voltage value of each battery in the first battery pack, measured at different timings, and a second current value flowing through the second measurement circuit and the voltage value of each battery in the second battery pack. The first measuring circuit has a first switch connected in series with the first battery pack. The second measurement circuit has a second switch connected in series with the second battery pack. The signal generation unit generates the control signal for turning on the first switch and the second switch in a mutually exclusive manner.

2. The battery monitoring device as described in claim 1, The first measuring circuit has a first transistor connected to the first battery pack as a first switch. The second measuring circuit has a second transistor connected to the second battery pack as a second switch. The control signal is a signal used to enable the first transistor and the second transistor to operate in a time-division manner during mutually independent periods.

3. The battery monitoring device as described in claim 2, The first control signal output to the first transistor and the second control signal output to the second transistor are rectangular wave signals that can be controlled at any period. The signal generation unit sets the duty cycle of the first control signal, which corresponds to the period of the first control signal, and sets the duty cycle of the second control signal, which corresponds to the period of the second control signal.

4. The battery monitoring device as described in claim 1, The first measurement circuit and a portion of the wiring harness in the second measurement circuit are shared.

5. The battery monitoring device as described in claim 4, The first measuring circuit has a first load resistor connected to the first battery pack for measuring the AC impedance and a first shunt resistor for measuring the current. The second measuring circuit has a second load resistor connected to the second battery pack for measuring the AC impedance and a second shunt resistor for measuring the current. The wiring harness, which is a common part of the harness, is configured to connect the negative terminal of the first battery pack and the positive terminal of the second battery pack to the first load resistor and the second load resistor.

6. The battery monitoring device as described in claim 4, The first measurement circuit includes: the first battery pack; and a first load resistor connected to the first battery pack for measuring the AC impedance and a first shunt resistor for measuring the current. The second measuring circuit includes: the second battery pack; and a second load resistor connected to the second battery pack for measuring the AC impedance and a second shunt resistor for measuring the current. The first load resistor and the second load resistor are disposed on the common part of the wiring harness.

7. The battery monitoring device as described in claim 5 or 6, The battery monitoring device also includes an integrated circuit. The integrated circuit comprises: The first current measuring unit is used to measure the current flowing through the first shunt resistor; The first voltage measuring unit is used to measure the voltage of each battery in the first battery pack; The first impedance measurement calculation unit calculates the AC impedance of each cell in the first battery pack based on the current value measured by the first current measurement unit and the voltage value of each cell in the first battery pack measured by the first voltage measurement unit. The second current measuring unit is used to measure the current flowing through the second shunt resistor; The second voltage measuring unit is used to measure the voltage of each battery in the second battery pack; as well as The second impedance measurement calculation unit calculates the AC impedance of each cell in the second battery pack based on the current value measured by the second current measurement unit and the voltage value of each cell in the second battery pack measured by the second voltage measurement unit.

8. The battery monitoring device as described in claim 5 or 6, The bottom battery of the first battery pack is connected to the top battery of the second battery pack. The positive terminal of the uppermost battery in the first battery pack is connected to the first shunt resistor. The first shunt resistor is connected to the first transistor, which acts as the first switch. The negative terminal of the bottommost battery in the second battery pack is connected to the second shunt resistor. The second shunt resistor is connected to the second transistor, which acts as the second switch.

9. The battery monitoring device as described in claim 1, The plurality of batteries includes one or more batteries that are included in both the first battery pack and the second battery pack.

10. The battery monitoring device as described in any one of claims 1 to 6 and 9, The bottom battery of the first battery pack is connected to the top battery of the second battery pack. The battery monitoring device includes a computing unit that performs at least one of the following based on the AC impedance of the bottommost battery in the first battery pack and the AC impedance of the topmost battery in the second battery pack: fault determination and AC impedance correction. The fault determination refers to determining faults in the first measurement circuit and the second measurement circuit, and the AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

11. The battery monitoring device as described in any one of claims 1 to 6 and 9, The battery monitoring device includes: A first computing unit estimates a first capacity retention rate of the first battery based on the AC impedance of any first battery included in the first battery pack, and estimates a second capacity retention rate of the second battery based on the AC impedance of any second battery included in the second battery pack; and The second calculation unit, based on the third capacity retention rate of the first battery and the fourth capacity retention rate of the second battery, which are estimated from parameters other than AC impedance, and the first capacity retention rate and the second capacity retention rate, performs at least one of fault determination and AC impedance correction. The fault determination refers to determining a fault in the first measurement circuit and the second measurement circuit, and the AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

12. The battery monitoring device as described in any one of claims 1 to 6 and 9, The bottom battery of the first battery pack is connected to the top battery of the second battery pack. The battery monitoring device includes: A temperature measurement unit measures the temperature of the bottommost battery and the topmost battery based on the outputs of a first temperature sensor and a second temperature sensor. The first temperature sensor measures the temperature of the bottommost battery in the first battery pack, and the second temperature sensor measures the temperature of the topmost battery in the second battery pack. The battery state calculation unit, based on the internal temperature of the bottommost battery estimated from the AC impedance of the bottommost battery in the first battery pack, and the temperatures of the topmost battery and the bottommost battery respectively measured by the temperature measurement unit, performs at least one of fault determination and AC impedance correction. The fault determination refers to determining faults in the first measurement circuit and the second measurement circuit, and the AC impedance correction refers to correcting the AC impedance of each of the plurality of batteries obtained by measurement.

13. A battery monitoring method, wherein in the battery monitoring method, Control signals are generated to control the first and second measurement circuits. The first measurement circuit is connected to the first battery pack, and the second measurement circuit is connected to the second battery pack. The first and second battery packs are obtained by dividing multiple batteries connected in series. Based on the first current value flowing through the first measuring circuit and the voltage values ​​of each battery in the first battery pack, measured at different time intervals, and the second current value flowing through the second measuring circuit and the voltage values ​​of each battery in the second battery pack, the AC impedance of each of the plurality of batteries is calculated. The first measuring circuit has a first switch connected in series with the first battery pack. The second measuring circuit has a second switch connected in series with the second battery pack. In generating the control signal, a control signal is generated to enable the first switch and the second switch to be turned on in a mutually exclusive manner.

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