Battery condition detection device and battery management system

Abstract

To provide a battery state detection device capable of detecting battery internal impedance with more flexibility in terms of timing.SOLUTION: A battery state detection device is provided, comprising a variable signal generation unit provided separately from a battery load to generate a variable signal with a variable frequency and a voltage higher than that of a battery output, and an impedance acquisition unit configured to acquire voltage-current characteristics when the variable signal is applied to a battery to acquire internal impedance of the battery based on the voltage-current characteristics.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 below discloses a detection device that can accurately detect the internal resistance value of a secondary battery. This detection device applies the well-known "Cole-Cole Plot" AC method to detect the internal resistance value of a secondary battery, and detects the internal resistance value of the secondary battery based on the voltage-current characteristics of the secondary battery when the frequency of an AC signal applied to the secondary battery is varied. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-175556 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned background art, the frequency of the AC signal is varied by a motor drive inverter corresponding to the load of the secondary battery (battery), so the internal resistance value (internal impedance) of the secondary battery cannot be detected depending on the driving state of the vehicle motor driven by the motor drive inverter. In other words, in the background art, the detection of the battery's internal resistance value is possible depending on the driving state of the vehicle motor, so there is a problem in that the degree of freedom in the timing of detecting the battery's internal resistance value is limited.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a battery state detection device that can detect the internal impedance of a battery at more flexible timing than conventional devices. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention adopts a solution relating to a battery state detection device, which comprises a fluctuation signal generating unit that is provided separately from the battery load and generates a fluctuation signal that has a higher voltage than the battery output and a freely variable frequency, and an impedance obtaining unit that obtains the voltage-current characteristics when the fluctuation signal is applied to the battery and obtains the internal impedance of the battery based on the voltage-current characteristics. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a battery state detection device that can detect the internal impedance of a battery at more flexible timing than conventional devices. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a battery state detection device A according to one embodiment of the present invention. [Figure 2] 3 is a flowchart showing the operation of a battery state detection device A according to one embodiment of the present invention. [Figure 3] 4 is a timing chart showing the operation of the charge pump 3 in one embodiment of the present invention. [Figure 4] 1 is a schematic diagram showing an equivalent circuit and a Cole-Cole plot of a battery X in a first embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1, the battery state detection device A according to this embodiment is a state detection device that detects a battery X. This battery state detection device A includes an infrared temperature sensor 1, multiple voltage detection ICs 2, a charge pump 3, three interface circuits 4 to 6, and an MPU 7, and detects the internal impedance of the battery X based on detection signals input from the infrared temperature sensor 1 and multiple voltage detection ICs 2 that are incidentally provided on the battery X.

[0010] The battery X to be detected is a secondary battery in which multiple battery cells are connected in series. More precisely, this battery X is a battery module in which multiple battery cells are connected in series. Such a battery X is mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle, and supplies DC power to a PCU (Power Control Unit) that drives the driving motor.

[0011] This battery X is, for example, a lithium-ion battery or a fuel cell, and supplies a relatively high voltage (for example, several hundred volts) battery output (DC power) to a load such as a PCU. The traction motor is an electric motor that generates the driving power for the electric vehicle, i.e., the rotational power for the drive wheels of the electric vehicle. PCU is an abbreviation for power control unit, and is a power conversion circuit (motor drive circuit) that drives the traction motor.

[0012] The infrared temperature sensor 1 is a temperature sensor attached to the battery X. This infrared temperature sensor 1 detects the operating temperature t of the battery X as the battery temperature by using infrared rays as a temperature detection medium. Such an infrared temperature sensor 1 outputs a temperature detection signal indicating the battery temperature t to the MPU 7.

[0013] The voltage detection IC2 is provided for each battery module, for example, and detects the output voltage of each battery cell in the corresponding battery module as a cell voltage. These voltage detection IC2s output cell voltage detection signals indicating the cell voltage of each battery cell to the MPU 7.

[0014] The voltage detection IC2 also has the function of detecting the current (battery current) flowing from or into the battery X. In addition to the cell voltage detection signal, the voltage detection IC2 outputs a current detection signal indicating the battery current to the MPU 7.

[0015] The charge pump 3 is provided separately from the PCU, which is a load of the battery X, and is a variable signal generating unit that generates a variable signal Vs that has a higher voltage than the battery output and a freely variable frequency based on the battery output input from the battery X as a power source.

[0016] As shown in the figure, the charge pump 3 includes a first transistor 3a, a second transistor 3b, a third transistor 3c, a first capacitor 3d, a first resistor 3e, a second resistor 3f, and a second capacitor 3g. Of the components of this charge pump 3, the first transistor 3a corresponds to the first electronic switch of the present invention, the second transistor 3b corresponds to the second electronic switch of the present invention, and the third transistor 3c corresponds to the third electronic switch of the present invention.

[0017] The first transistor 3a has a drain terminal connected to the positive electrode of the battery X, a source terminal connected to the drain terminal of the second transistor 3b and one end of the first capacitor 3d, and a gate terminal connected to the output terminal of the first interface circuit 4. That is, the first transistor 3a is provided between one end of the first capacitor 3d and the positive electrode of the battery X, and is turned ON / OFF (conductive / non-conductive) based on a first gate signal input to the gate terminal from the first interface circuit 4.

[0018] The second transistor 3b has a drain terminal connected to the source terminal of the first transistor 3a and one end of the first capacitor 3d, a source terminal connected to the negative electrode of the battery X, and a gate terminal connected to the output terminal of the second interface circuit 5. That is, the second transistor 3b is provided between one end of the first capacitor 3d and the negative electrode of the battery X, and is turned ON / OFF (conductive / non-conductive) based on a second gate signal input to the gate terminal from the second interface circuit 5.

[0019] The third transistor 3c has a drain terminal connected to the positive electrode of the battery X, a source terminal connected to one end of the first resistor 3e and one end of the second resistor 3f, and a gate terminal connected to the output terminal of the third interface circuit 6. That is, the first transistor 3a is provided between the positive electrode of the battery X and one end of the first resistor 3e and one end of the second resistor 3f, and is turned ON / OFF (conductive / non-conductive) based on a third gate signal input to the gate terminal from the third interface circuit 6.

[0020] The first capacitor 3d is connected in series with the first resistor 3e to form a first series circuit together with the first resistor 3e. One end of the first capacitor 3d is connected to the source terminal of the first transistor 3a and the drain terminal of the second transistor 3b, and the other end is connected to the other end of the first resistor 3e. This one end of the first capacitor 3d corresponds to one end of the first series circuit.

[0021] The first resistor 3e is connected in series with the first capacitor 3d, and together with the first capacitor 3d, forms a first series circuit. One end of the first resistor 3e is connected to the source terminal of the third transistor 3c and one end of the second resistor 3f, and the other end is connected to the other end of the first capacitor 3d. That is, the first series circuit in this embodiment is formed by connecting the first capacitor 3d and the first resistor 3e in series.

[0022] The second resistor 3f is connected in series with the second capacitor 3g to form a second series circuit together with the second capacitor 3g. One end of the second resistor 3f is connected to the source terminal of the third transistor 3c and one end of the first resistor 3e, and the other end is connected to one end of the second capacitor 3g.

[0023] The second capacitor 3g is connected in series with the second resistor 3f and forms a second series circuit together with the second resistor 3f. One end of the second capacitor 3g is connected to the other end of the second resistor 3f, and the other end is connected to the negative electrode of the battery X. That is, the second series circuit in this embodiment includes the second capacitor 3f and the second resistor 3g connected in series, and one end is connected to the other end of the first series circuit, and the other end is connected to the negative electrode of the battery X.

[0024] Of the three interface circuits 4 to 6, the first interface circuit 4 has an input terminal connected to the first output terminal of the MPU 7 and an output terminal connected to the gate terminal of the first transistor 3a. The first interface circuit 4 is a buffer circuit provided between the first transistor 3a and the MPU 7.

[0025] Here, the first transistor 3a is a high-voltage power supply system circuit element that operates using battery X as its power source. In contrast, the MPU 7 is a low-voltage power supply system circuit element that is driven by a low-voltage power supply of, for example, about 5 V, different from battery X. The first interface circuit 4 eliminates or suppresses power supply interference between the first transistor 3a and the MPU 7, which operate on different power supply systems.

[0026] The first interface circuit 4 also functions as a voltage converter that converts the first control signal GS1 input from the MPU 7 into a voltage capable of driving the first transistor 3a. That is, since the first control signal GS1 of the MPU 7 does not have a voltage capable of reliably turning the first transistor 3a on / off (conducting / cutting off), the first interface circuit 4 converts the first control signal GS1 of the MPU 7 into a signal, i.e., a first gate signal, that can reliably turn the first transistor 3a on / off (conducting / cutting off).

[0027] The second interface circuit 5 has an input terminal connected to the second output terminal of the MPU 7 and an output terminal connected to the gate terminal of the second transistor 3 b. The second interface circuit 5 is a buffer circuit provided between the second transistor 3 b and the MPU 7.

[0028] The second transistor 3b is a high-voltage power supply system circuit element that operates using battery X as its power source. In contrast, as described above, the MPU 7 is a low-voltage power supply system circuit element that is driven by a low-voltage power supply of, for example, about 5 V, different from battery X. The second interface circuit 5 eliminates or suppresses power supply interference between the second transistor 3b and the MPU 7, which operate on different power supply systems.

[0029] The second interface circuit 5 also functions as a voltage converter that converts the second control signal GS2 input from the MPU 7 into a voltage that can drive the second transistor 3b. That is, since the second control signal GS2 of the MPU 7 does not have a voltage that can reliably turn the second transistor 3b on / off (conduct / cut off), the second interface circuit 5 converts the second control signal GS2 of the MPU 7 into a signal that can reliably turn the second transistor 3b on / off (conduct / cut off), that is, into a second gate signal.

[0030] The third interface circuit 6 has an input terminal connected to the third output terminal of the MPU 7 and an output terminal connected to the gate terminal of the third transistor 3c. The third interface circuit 6 is a buffer circuit provided between the third transistor 3c and the MPU 7.

[0031] The third transistor 3c is a high-voltage power supply circuit element that operates using battery X as its power source. In contrast, as described above, the MPU 7 is a low-voltage power supply circuit element that is driven by a low-voltage power supply of, for example, about 5 V, different from battery X. The third interface circuit 6 eliminates or suppresses power supply interference between the third transistor 3c and the MPU 7, which operate on different power supply systems.

[0032] The third interface circuit 6 also functions as a voltage converter that converts the third control signal GS3 input from the MPU 7 into a voltage that can drive the third transistor 3c. That is, since the third control signal GS3 of the MPU 7 does not have a voltage that can reliably turn the third transistor 3c ON / OFF (conduction / cut-off), the third interface circuit 6 converts the third control signal GS3 of the MPU 7 into a signal that can reliably turn the third transistor 3c ON / OFF (conduction / cut-off), that is, a third gate signal.

[0033] The MPU 7 is an impedance acquisition unit that acquires the voltage-current characteristics of the battery X when the fluctuation signal Vs generated by the charge pump 3 is applied to the battery X, and acquires the internal impedance of the battery X based on the voltage-current characteristics. The MPU 7 acquires the internal impedance of the battery X by executing a battery monitoring program stored in advance.

[0034] That is, the MPU 7 generates first to third control signals based on the battery monitoring program to control the charge pump 3, and acquires the internal impedance of the battery X based on the temperature detection signal, current detection signal, and voltage detection signal input from the infrared temperature sensor 1 and multiple voltage detection ICs 2, respectively, as a result of operation of the charge pump 3.

[0035] The MPU 7 acquires the internal impedance of the battery X based on the well-known AC impedance method, which will be described in detail later. This AC impedance method is also called the Cole-Cole Plot or Nyquist Plot. This AC impedance method estimates the internal impedance of the battery X based on the battery voltage and battery current (current-voltage characteristics) when an AC signal in a predetermined frequency band is applied to the battery.

[0036] Although details will be given later, in the AC impedance method, a battery, which is an electrochemical device, is regarded as an equivalent circuit consisting of solution resistance, charge transfer resistance, diffusion resistance, and interfacial capacitance (electrostatic capacitance), and the impedance values ​​obtained by subjecting the battery voltage and battery current to a discrete Fourier transform are plotted in order on a chart with the real component of the AC impedance on the horizontal axis and the imaginary component of the AC impedance on the vertical axis, thereby determining the element values ​​of the equivalent circuit.

[0037] Here, the battery state detection device A according to this embodiment constitutes a battery management system that manages the battery X that is the detection target. That is, the battery state detection device A has a function of determining the deterioration state of the battery X by estimating the internal impedance, as well as various additional functions for managing the battery X, such as controlling the connection between the battery X and a load.

[0038] Next, the operation of the battery state detection device A according to this embodiment will be described in detail with reference to FIGS.

[0039] When the IG-SW (ignition switch) of the electric vehicle is set to "OFF" (step S1), the MPU 7 of this battery state detection device A detects the battery temperature t of battery X based on the temperature detection signal (step S2). That is, when the driver sets the IG-SW from "ON" to "OFF" and the electric vehicle stops traveling, the MPU 7 starts acquiring the internal impedance of battery X based on the battery monitoring program.

[0040] The condition in step S1 (traveling stop condition) arises because when the electric vehicle is traveling, the load fluctuation of battery X becomes relatively large, which reduces the accuracy of estimating the internal impedance of battery X based on the AC impedance method. MPU 7 estimates the internal impedance of battery X in a state where there is no load fluctuation of battery X (a state where the load is disconnected).

[0041] Then, the MPU 7 determines whether the battery temperature t acquired in step S2 exceeds 0°C (step S3), and if the determination in step S3 is "Yes", starts the operation of the charge pump 3 (step S4). Note that if the determination in step S3 is "No", the MPU 7 does not start the operation of the charge pump 3 and ends the acquisition of the internal impedance of the battery X.

[0042] That is, the MPU 7 starts the operation of the charge pump 3 on the condition that the electric vehicle stops traveling and the battery temperature t exceeds 0°C, thereby acquiring the internal impedance of the battery X. Note that 0°C corresponds to the temperature threshold value of the present invention.

[0043] The condition (temperature condition) in step S3 arises from the fact that the estimation accuracy of the internal impedance of battery X based on the AC impedance method decreases when the battery temperature t is equal to or lower than 0° C. In other words, the MPU 7 estimates the internal impedance of battery X in the operating temperature range of battery X above 0° C., where the estimation accuracy of the internal impedance becomes relatively high.

[0044] 3 and outputs it to the first interface circuit 4. The MPU 7 also generates a second control signal GS2 synchronized with the first control signal GS1 and outputs it to the second interface circuit 5, and also generates a third control signal GS3 synchronized with the first control signal GS1 and outputs it to the third interface circuit 6. The first to third control signals GS1 to GS3 are pulse signals whose repetition period becomes shorter with the passage of time, as shown in the figure.

[0045] The first interface circuit 4 converts the first control signal GS1 into a first gate signal and outputs it to the base terminal of the first transistor 3a. The second interface circuit 5 converts the second control signal GS2 into a second gate signal and outputs it to the base terminal of the second transistor 3b. The third interface circuit 6 converts the third control signal GS3 into a third gate signal and outputs it to the base terminal of the third transistor 3c.

[0046] As a result, the output voltage Vb of the battery X, which is applied from the battery X to the drain terminal of the first transistor 3a and the source terminal of the second transistor 3b, is converted into a fluctuating signal Vs whose minimum voltage is the output voltage Vb and whose maximum voltage is twice the output voltage Vb, as shown in FIG. 3, and is applied to the battery X via the third transistor 3c.

[0047] Here, as shown in Figure 3, the variable signal Vs gradually increases in voltage from the output voltage Vb to a voltage twice the output voltage Vb during the period when the first control signal GS1 and the second control signal GS2 are at low level and the third control signal GS3 is at high level, and gradually decreases in voltage during the period when the first control signal GS1 is at low level and the second control signal GS2 and the third control signal GS3 are at high level, and during the period when the first control signal GS1 is at high level and the second control signal GS2 and the third control signal GS3 are at low level.

[0048] That is, the fluctuation signal Vs generated by the charge pump 3 based on the output voltage Vb of the battery X is a voltage fluctuation signal that has a voltage equal to or greater than the output voltage Vb of the battery X and whose fluctuation period Ts changes over time in accordance with changes in the repetition period of the first to third control signals GS1 to SG3. When such a fluctuation signal Vs is applied to the battery X, a current for estimating the internal impedance flows into the battery X.

[0049] The MPU 7 sequentially detects the cell voltage V and battery current I (cell current) of the battery X caused by the fluctuation signal Vs based on the current detection signal and the voltage detection signal at predetermined time intervals (step S5).Then, the MPU 7 sequentially detects the voltage change rate ΔV and the current change rate ΔI based on the cell voltage V and battery current I obtained sequentially in time series (step S6).

[0050] Then, the MPU 7 obtains the "Cole-Cole Plot" shown in FIG. 4(a) based on the voltage change rate ΔV and the current change rate ΔI. Each part of this Cole-Cole plot corresponds to each element value of the equivalent circuit of battery X shown in FIG. 4(b). The relationship between this equivalent circuit and each part of the Cole-Cole plot is well known as the AC impedance method described above.

[0051] That is, the MPU 7 obtains a Cole-Cole plot based on the voltage-current characteristics of the battery X when the fluctuation signal Vs is applied, and estimates the internal impedance of the battery X based on the Cole-Cole plot.

[0052] A Cole-Cole plot is a chart in which the impedance of an equivalent circuit (electrical circuit) consisting of a solution resistance Rsol, a reaction resistance Rct (charge transfer resistance), a diffusion resistance Zw, and an interfacial capacitance C (electrostatic capacitance) is shown on a chart with the real component (horizontal axis) and the imaginary component (vertical axis).

[0053] In such a Cole-Cole plot, the horizontal axis of the locus from the origin to point A corresponds to the solution resistance Rsol. The horizontal axis of the locus from point A to point B corresponds to the reaction resistance Rct (charge transfer resistance). The horizontal axis of the locus from point B to point C corresponds to the diffusion resistance Zw.

[0054] When the MPU 7 acquires such a Cole-Cole plot for the battery X, it acquires the coordinate values ​​(real number Zj and imaginary number Zk) of the point C. The coordinate values ​​(real number Zj and imaginary number Zk) of the point C are values ​​that change depending on the deterioration state of the battery X.

[0055] After acquiring the coordinate values ​​(real number Zj and imaginary number Zk) of point C in this manner, the MPU 7 evaluates the real number Zj and the imaginary number Zk. That is, the MPU 7 determines whether the real number Zj is greater than a predetermined first evaluation threshold Zr1 (step S9). If the determination in step S9 is "Yes," that is, if the real number Zj exceeds the first evaluation threshold Zr1, the MPU 7 internally stores a degradation warning indicating that battery X is degraded (step S10).

[0056] This deterioration warning is read and notified the next time the IG-SW (ignition switch) of the electric vehicle is set to "ON," that is, the next time the driver tries to drive the electric vehicle. This deterioration warning allows the driver to recognize that Battery X has deteriorated and requires maintenance.

[0057] On the other hand, if the determination in step S9 is "No," that is, if the real number Zj is equal to or less than the first evaluation threshold Zr1, the MPU 7 does not internally store the deterioration warning, but instead determines whether the imaginary number Zk of point C is greater than a predetermined second evaluation threshold Zr2 (step S11).If the determination in step S10 is "Yes," that is, if the imaginary number Zk exceeds the second evaluation threshold Zr2, the MPU 7 internally stores the deterioration warning (step S10).

[0058] If the determination in step S11 is "No," that is, if the imaginary number Zk is equal to or smaller than the second evaluation threshold Zr2, the MPU 7 ends the acquisition of the internal impedance of the battery X without internally storing the deterioration warning.

[0059] The battery state detection device A of this embodiment is provided separately from the load (PCU, etc.) of the battery X and includes a charge pump 3 (fluctuation signal generation unit) that generates a fluctuation signal Vs that has a higher voltage than the battery output and whose frequency is freely variable, and an MPU 7 (impedance acquisition unit) that acquires the voltage-current characteristics when the fluctuation signal Vs is applied to the battery X and acquires the internal impedance of the battery X based on the voltage-current characteristics.

[0060] Such a battery state detecting device A makes it possible to detect the internal impedance of the battery at more flexible timing than conventionally possible, without depending on the load on the battery X. That is, according to this embodiment, it is possible to provide a battery state detecting device A that can detect the internal impedance of the battery at more flexible timing than conventionally possible.

[0061] Furthermore, this battery state detection device A further includes an infrared temperature sensor 1 (temperature detection unit) that detects the temperature of battery X as battery temperature t, and the MPU 7 (impedance acquisition unit) acquires the internal impedance of battery X when battery temperature t is higher than 0°C (predetermined temperature threshold), making it possible to acquire internal impedance with relatively high accuracy.

[0062] Furthermore, in this battery state detection device A, the fluctuation signal generation unit is the charge pump 3 that generates the fluctuation signal Vs based on the battery output, so it is possible to generate the fluctuation signal Vs with a simple circuit configuration, thereby reducing the number of parts that make up the fluctuation signal generation unit and suppressing cost increases.

[0063] Furthermore, according to this battery state detection device A, the charge pump 3 includes a first series circuit in which a first capacitor 3d and a first resistor 3e are connected in series, a first transistor 3a (first electronic switch) provided between one end of the first series circuit and the positive electrode of battery X, a second series circuit including a second capacitor 3f and a second resistor 3g connected in series, one end connected to the other end of the first series circuit and the other end connected to the negative electrode of battery X, a second transistor 3b (second electronic switch) provided between one end of the first series circuit and the negative electrode of battery X, and a third transistor 3c (third electronic switch) provided between the positive electrode of battery X and the other end of the first series circuit. Such a battery state detection device A can generate a fluctuation signal Vs that fluctuates relatively slowly, as shown in FIG.

[0064] The present invention is not limited to the above-described embodiment, and the following modifications are possible. (1) In the above embodiment, the battery X mounted on an electric vehicle is the detection target, but the present invention is not limited to this. The present invention can be applied to the deterioration diagnosis of various batteries other than those mounted on vehicles.

[0065] (2) In the above embodiment, the charge pump 3 shown in Fig. 1 is used as the fluctuation signal generator, but the present invention is not limited to this. That is, the fluctuation signal generator in the present invention is not limited to the charge pump 3 having the configuration shown in Fig. 1.

[0066] (3) In the above embodiment, the internal impedance is acquired when the driving stop condition and the temperature condition are satisfied, but the present invention is not limited to this. If necessary, the internal impedance may be acquired without considering the driving stop condition and the temperature condition, or without considering the driving stop condition or the temperature condition, and the deterioration diagnosis of battery X may be performed.

[0067] (Appendix 1) A battery state detection device comprising: a fluctuation signal generation unit that is provided separately from the battery load and generates a fluctuation signal that has a higher voltage than the battery output and a freely variable frequency; and an impedance acquisition unit that acquires the voltage-current characteristics when the fluctuation signal is applied to the battery and acquires the internal impedance of the battery based on the voltage-current characteristics.

[0068] (Appendix 2) A battery state detection device as described in Appendix 1, further comprising a temperature detection unit that detects the temperature of the battery as a battery temperature, and the impedance acquisition unit acquires the internal impedance when the battery temperature is higher than a predetermined temperature threshold.

[0069] (Appendix 3) 3. The battery state detection device according to claim 1, wherein the fluctuation signal generating unit is a charge pump that generates the fluctuation signal based on the battery output.

[0070] (Appendix 4) the charge pump includes a first series circuit in which a first capacitor and a first resistor are connected in series; a first electronic switch provided between one end of the first series circuit and the positive electrode of the battery; a second series circuit including a second capacitor and a second resistor connected in series, the second series circuit having one end connected to the other end of the first series circuit and the other end connected to the negative electrode of the battery; a second electronic switch provided between one end of the first series circuit and the negative electrode of the battery; and a third electronic switch provided between the positive electrode of the battery and the other end of the first series circuit.

[0071] (Appendix 5) A battery management system comprising the battery state detection device according to any one of Supplementary notes 1 to 3. [Explanation of symbols]

[0072] A. Battery status detection device X Battery 1 Infrared temperature sensor 2 Cell voltage detection IC 3 Charge pump (variable signal generator) 3a First transistor (first electronic switch) 3b Second transistor (second electronic switch) 3c Third transistor (third electronic switch) 3d First Capacitor 3e First Resistor 3f Second Resistor 3g Second capacitor 4~6 Interface circuit 7 MPU (impedance acquisition unit)

Claims

1. a variable signal generating unit provided separately from the battery load, which generates a variable signal having a higher voltage than the battery output and a variable frequency; an impedance acquisition unit that acquires a voltage-current characteristic when the fluctuation signal is applied to the battery and acquires an internal impedance of the battery based on the voltage-current characteristic; the fluctuation signal generating unit is a charge pump that generates the fluctuation signal based on the battery output, The charge pump a first series circuit in which a first capacitor and a first resistor are connected in series; a first electronic switch provided between one end of the first series circuit and the positive electrode of the battery; a second series circuit including a second capacitor and a second resistor connected in series, one end of the second series circuit being connected to the other end of the first series circuit and the other end being connected to the negative electrode of the battery; a second electronic switch provided between one end of the first series circuit and the negative electrode of the battery; a third electronic switch provided between the positive electrode of the battery and the other end of the first series circuit;

2. a temperature detection unit that detects the temperature of the battery as a battery temperature; The battery state detection device according to claim 1 , wherein the impedance acquisition unit acquires the internal impedance when the battery temperature is higher than a predetermined temperature threshold value.

3. A battery management system equipped with a battery status detection device according to claim 1 or 2.

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