EIS detection circuit based on direct current sampling

Abstract

The embodiment of the utility model provides an EIS detection circuit based on direct current sampling, and belongs to the technical field of electronic circuits. The EIS detection circuit comprises an impedance detection circuit which comprises a first end and a second end which are used for being connected with a battery pack to be detected; the direct current sampling circuit comprises a voltage compensation module and a first operational amplifier module, the positive phase input end of the first operational amplifier module is connected to the first end, the negative phase input end of the first operational amplifier module is connected to the second end, and the voltage compensation module is connected to the positive phase input end of the first operational amplifier module; the output end of the first operational amplification module is connected with a controller of the impedance detection circuit, so that the controller determines the connection condition of the to-be-detected battery pack in the impedance detection circuit, and the constant voltage of the voltage compensation module is larger than the battery voltage of the to-be-detected battery pack. According to the embodiment of the invention, the on state and reverse connection condition of the battery can be detected in real time in the process of performing EIS detection on the to-be-detected battery.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to an EIS detection circuit based on direct current sampling. Background Art

[0002] Capacity determination is an important step in the battery production process. Through the capacity determination system, the battery can be charged with low and high currents, and certain charge and discharge tests can be performed to determine the product grade standard of the battery. In this process, current measurement plays a vital role.

[0003] The existing EIS (Electrochemical Impedance Spectroscopy) detection circuit can usually effectively measure the internal electrical parameters of the battery, such as internal resistance, capacity, etc., during the battery detection process to evaluate the battery's performance and health status. However, the circuit cannot detect the battery's on / off and reverse connection conditions at the same time, which may make it impossible to accurately judge the safety and reliability of the battery in actual use. Therefore, how to achieve effective detection and monitoring of the battery's on / off and reverse connection conditions has become an important issue to be solved. Utility Model Content

[0004] The main purpose of the embodiments of the present application is to provide an EIS detection circuit based on DC sampling, which can detect the connection state and reverse connection state of the battery in real time.

[0005] To achieve the above object, a first aspect of an embodiment of the present application proposes an EIS detection circuit based on DC sampling, comprising:

[0006] An impedance detection circuit, comprising a first terminal and a second terminal for connecting to a battery pack to be tested;

[0007] A DC sampling circuit includes a voltage compensation module and a first operational amplifier module, wherein the non-inverting input terminal of the first operational amplifier module is connected to the first terminal, and the inverting input terminal is connected to the second terminal, the voltage compensation module is connected to the non-inverting input terminal of the first operational amplifier module, and the output terminal of the first operational amplifier module is connected to the controller of the impedance detection circuit so that the controller determines the connection status of the battery pack to be tested in the impedance detection circuit, wherein the constant voltage of the voltage compensation module is greater than the battery voltage of the battery pack to be tested.

[0008] In some embodiments, the DC sampling circuit further includes a sampling chip, which is connected to the output end of the first operational amplifier module, and the sampling chip is connected to the controller so that the controller determines the connection status of the battery pack to be tested in the impedance detection circuit.

[0009] In some embodiments, the impedance detection circuit includes an impedance measurement module and a sampling resistor, the sampling resistor is connected to the battery pack to be tested, and the impedance measurement module is used to sample the instantaneous voltage across the sampling resistor or the instantaneous voltage across the battery to be tested in the battery pack to be tested.

[0010] In some embodiments, the impedance measurement module includes an impedance measurement chip, a current wave generation module and a signal detection module; the current wave generation module is connected to the impedance measurement chip to amplify the excitation current output by the impedance measurement chip, the signal detection module is used to connect the battery pack to be tested or the branch where the sampling resistor is located, and the impedance measurement chip is connected to the signal detection module to determine the impedance value of the battery pack to be tested.

[0011] In some embodiments, the signal detection module includes an analog switch and a second operational amplifier module, the analog switch is respectively connected to the sampling resistor and the battery pack to be tested, the controller is also used to send a selection signal, the signal detection module is used to receive the selection signal to connect the battery to be tested or the branch where the sampling resistor is located through the analog switch, and the second operational amplifier module is connected to the analog switch to amplify the sampling signal output by the signal detection module.

[0012] In some embodiments, the impedance measurement module also includes an analog-to-digital converter and a discrete Fourier transform unit, the analog-to-digital converter is used to receive the sampling signal to determine the impedance data corresponding to the battery to be tested, and the discrete Fourier transform unit is connected to the analog-to-digital converter to perform a discrete Fourier transform on the impedance data to obtain a target impedance value.

[0013] In some embodiments, the impedance measurement module further includes a storage unit connected to the discrete Fourier transform unit to store the target impedance value.

[0014] In some embodiments, the current wave generating module includes a Darlington transistor and a current limiting resistor, the Darlington transistor includes a first NPN transistor and a second NPN transistor, the base of the first NPN transistor is connected to the impedance measurement chip, the emitter of the first NPN transistor is connected to the sampling resistor, the collector of the first NPN transistor is connected to the base of the second NPN transistor, the emitter of the second NPN transistor is connected between the emitter of the first NPN transistor and the sampling resistor, and the collector of the second NPN transistor is connected to the current limiting resistor.

[0015] In some embodiments, the voltage compensation module includes a constant voltage source connected to a non-inverting input terminal of the first operational amplifier module.

[0016] In some embodiments, the DC sampling circuit also includes a circuit board measurement circuit, which is connected to the first operational amplifier module, and the circuit board measurement circuit is used to measure the voltage across a test board, wherein the test board is connected to the battery pack to be tested via a connecting line.

[0017] The EIS detection circuit based on DC sampling proposed in the embodiment of the present application has the following beneficial effects: the positive input terminal of the first operational amplifier module is connected to the first terminal in the impedance detection circuit, and the negative input terminal is connected to the second terminal of the impedance detection circuit. The signal of the battery pack to be tested is sampled and differential operation is performed through the first operational amplifier module to realize DC sampling of the battery pack to be tested, and the voltage compensation module is connected to the positive input terminal of the first operational amplifier module, and the constant voltage of the voltage compensation module is greater than the battery voltage of the battery pack to be tested, thereby ensuring that the output value of the first operational amplifier module is always positive, avoiding the problem of being unable to distinguish the specific connection status of the battery due to negative value sampling, and the output terminal of the first operational amplifier module is connected to the controller of the impedance detection circuit, so that the controller can determine the connection status of the battery pack to be tested in the impedance detection circuit according to the output status of the output terminal of the first operational amplifier module, thereby accurately determining the connection status and positive and reverse connection status of the battery pack to be tested, and realizing real-time detection of the connection state and reverse connection status of the battery. In this embodiment, the voltage compensation module is connected to the non-phase input terminal of the first operational amplifier module, thereby ensuring that the output value of the first operational amplifier module is always positive, achieving accurate judgment of the battery connection state and reverse connection condition, simplifying the data processing process, and improving the stability and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the framework of the EIS detection circuit based on DC sampling provided in an embodiment of the present application;

[0019] Figure 2 is a circuit diagram of a DC sampling circuit provided in an embodiment of the present application;

[0020] Figure 3 is a circuit diagram of a current wave generating module provided in an embodiment of the present application;

[0021] Figure 4 It is a schematic diagram of the pluggable terminal provided in the embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first", "second", etc. in the specification, claims and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0025] Capacity determination is an important step in the battery production process. Through the capacity determination system, the battery can be charged with low and high currents, and certain charge and discharge tests can be performed to determine the product grade standard of the battery. In this process, current measurement plays a vital role.

[0026] The existing EIS (Electrochemical Impedance Spectroscopy) detection circuit can usually effectively measure the internal electrical parameters of the battery, such as internal resistance, capacity, etc., during the battery detection process to evaluate the battery's performance and health status. However, the circuit cannot detect the battery's on / off and reverse connection conditions at the same time, which may make it impossible to accurately judge the safety and reliability of the battery in actual use. Therefore, how to achieve effective detection and monitoring of the battery's on / off and reverse connection conditions has become an important issue to be solved.

[0027] In order to solve the above problems, this embodiment provides an EIS detection circuit based on DC sampling, wherein the positive input terminal of the first operational amplifier module is connected to the first terminal in the impedance detection circuit, and the negative input terminal is connected to the second terminal of the impedance detection circuit. The signal of the battery pack to be tested is sampled and a differential operation is performed through the first operational amplifier module to realize DC sampling of the battery pack to be tested, and the voltage compensation module is connected to the positive input terminal of the first operational amplifier module, and the constant voltage of the voltage compensation module is greater than the battery voltage of the battery pack to be tested, thereby ensuring that the output value of the first operational amplifier module is always positive, avoiding the problem that the specific connection status of the battery cannot be distinguished due to negative value sampling, and the output terminal of the first operational amplifier module is connected to the controller of the impedance detection circuit, so that the controller can determine the connection status of the battery pack to be tested in the impedance detection circuit according to the output status of the output terminal of the first operational amplifier module, thereby accurately determining the connection status and positive and reverse connection status of the battery pack to be tested, and realizing real-time detection of the connection state and reverse connection status of the battery. In this embodiment, the voltage compensation module is connected to the non-phase input terminal of the first operational amplifier module, thereby ensuring that the output value of the first operational amplifier module is always positive, achieving accurate judgment of the battery connection state and reverse connection condition, simplifying the data processing process, and improving the stability and reliability of the circuit.

[0028] Please refer to Figure 1 , Figure 1 It is a schematic diagram of the framework of the EIS detection circuit based on DC sampling provided in an embodiment of the present application.

[0029] In some embodiments, the impedance detection circuit includes a first terminal 110 and a second terminal 120 for connecting to a battery group 130 to be tested, wherein the battery group 130 to be tested includes at least one battery to be tested, and the first terminal 110 and the second terminal 120 are respectively used to connect the positive and negative electrodes of the battery to be tested, for example, the first terminal 110 is connected to the positive electrode of the battery to be tested, and the second terminal 120 is connected to the negative electrode of the battery to be tested, or the first terminal 110 is connected to the negative electrode of the battery to be tested, and the second terminal 120 is connected to the positive electrode of the battery to be tested, and the like, and this embodiment does not make specific limitations.

[0030] It can be understood that when the first terminal 110 is connected to the positive electrode of the battery to be tested and the second terminal 120 is connected to the negative electrode of the battery to be tested, the positive input terminal of the first operational amplifier module 720 is connected to the second terminal 120, and the inverting input terminal is connected to the first terminal 110, then it can be judged as a reverse connection result. Similarly, when the first terminal 110 is connected to the negative electrode of the battery to be tested and the second terminal 120 is connected to the positive electrode of the battery to be tested, the positive input terminal of the first operational amplifier module 720 is connected to the first terminal 110, and the inverting input terminal is connected to the second terminal 120, then it can be judged as a reverse connection result.

[0031] It should be noted that the EIS detection circuit also includes a controller 200 and a communication module 300, wherein the controller 200 is a microcontroller unit (MCU), and the communication module 300 includes two communication modes: CAN (Controller Area Network) and RS-485, to realize information transmission between the test board and the intermediate computer.

[0032] It is worth noting that the controller 200 is composed of a GD32F450VE chip and related peripheral circuits, and can receive PC (Personal Computer) terminal signals through the communication module 300 to realize functions such as sending control signals downward and obtaining circuit measurement signals. The control signal includes commands such as AC voltage amplitude, DC bias voltage size, sampling frequency range, sampling points, gear switching, etc., and the measurement signal includes data such as the real and imaginary parts of impedance and DC voltage value.

[0033] In some embodiments, the impedance detection circuit includes an impedance measurement module and a sampling resistor 410. The sampling resistor 410 is connected to the battery pack 130 to be tested. The impedance measurement module is used to sample the instantaneous voltage across the battery to be tested in the battery pack 130 to be tested or the instantaneous voltage across the sampling resistor 410. By sampling the instantaneous voltage across the sampling resistor 410 and the battery to be tested, the battery status can be monitored in real time.

[0034] It is worth noting that the battery group 130 to be tested includes at least one battery to be tested. When there are multiple batteries to be tested in the battery group 130 to be tested, each battery to be tested is arranged in a different path.

[0035] In some embodiments, the impedance measurement module includes an impedance measurement chip 420, a current wave generating module 430 and a signal detection module; the current wave generating module 430 is connected to the impedance measurement chip 420 to amplify the excitation current output by the impedance measurement chip 420, so as to meet the demand for high current output and improve the stability and accuracy of signal transmission. The signal detection module is used to connect the branch where the battery pack 130 to be tested or the sampling resistor 410 is located, and each time a signal is selected to be given to the first operational amplifier module 720, and the first operational amplifier module 720 amplifies the signal, and the first operational amplifier module 720 is connected to the impedance measurement chip 420 to send the amplified sampling signal to the impedance measurement chip 420, and the impedance measurement chip 420 is connected to the signal detection module to determine the impedance value of the battery pack 130 to be tested, so that detailed information on battery performance can be obtained through the impedance value of the battery, and accurate evaluation of the performance and health status of the battery can be achieved.

[0036] It can be understood that the impedance measurement chip 420 obtains the loop current flowing through the sampling resistor 410 by dividing the voltage across the sampling resistor 410 obtained by sampling by the resistance value. Since the sampling resistor 410 and the battery pack 130 to be tested are connected in series, the current is also the current of the battery pack to be tested. The impedance value of the battery to be tested can be obtained by directly dividing the instantaneous voltage across the battery to be tested by the loop current.

[0037] It is worth noting that the maximum excitation current emitted by the impedance measurement chip 420 is 3 mA, and the current needs to be amplified. The current wave module 430 in this embodiment can increase the excitation current to 20 mA to 400 mA. The impedance measurement chip 420 receives instructions from the controller 200 via SPI (Serial Peripheral Interface) to realize the functions of excitation current wave generation, signal detection, and battery impedance calculation.

[0038] In some embodiments, the signal detection module includes an analog switch 500 and a second operational amplifier module 440, and the analog switch 500 is respectively connected to the sampling resistor 410 and the battery pack 130 to be tested. Specifically, the number of analog switches 500 is set according to the number of batteries to be tested in the battery pack 130 to be tested. The controller 200 is also used to send a selection signal. The signal detection module is used to receive the selection signal to connect the battery pack 130 to be tested or the branch where the sampling resistor 410 is located through the analog switch 500 according to the high and low levels of the selection signal. The second operational amplifier module 440 is connected to the analog switch 500 to amplify the sampling signal output by the signal detection module, and the signal is transmitted by connecting the channel where the battery to be tested or the sampling resistor 410 is located, so as to monitor the working status and performance of the battery pack.

[0039] It should be noted that, in this embodiment, the analog switch 500 is used to select the transmission of one channel signal each time, and the controller 200 selects the signal by controlling the high and low level states of the first signal and the second signal.

[0040] In some embodiments, the EIS detection circuit also includes an expansion board 600, and the controller 200 is connected to the expansion board 600 to expand the number of connection ports of the EIS detection circuit. Users can connect various sensors, actuators or other external devices through these ports to achieve richer functions.

[0041] Please refer to Figure 2 , Figure 2 is a circuit diagram of a DC sampling circuit provided in an embodiment of the present application.

[0042] In some embodiments, the DC sampling circuit includes a voltage compensation module 710 and a first operational amplifier module 720, wherein the positive input terminal of the first operational amplifier module 720 is connected to the first terminal 110, and the negative input terminal is connected to the second terminal 120, thereby realizing DC sampling of the battery to be tested, and the voltage compensation module 710 is connected to the positive input terminal of the first operational amplifier module 720, and the output terminal of the first operational amplifier module 720 is connected to the controller 200 of the impedance detection circuit, so that the controller 200 can determine the connection status of the battery group 130 to be tested in the impedance detection circuit according to the output status of the output terminal of the first operational amplifier module 720, wherein the constant voltage of the voltage compensation module 710 is greater than the battery voltage of the battery group 130 to be tested, thereby ensuring that the output value of the first operational amplifier module 720 is always positive, avoiding the situation where negative values ​​cannot be accurately sampled.

[0043] In some embodiments, the DC sampling circuit also includes a sampling chip 730, which is connected to the output end of the first operational amplifier module 720, so that the analog signal output by the first operational amplifier module 720 can be converted into a digital signal for processing and analysis by the controller 200. The sampling chip 730 is connected to the controller 200 so that the controller 200 can determine the connection status of the battery pack to be tested in the impedance detection circuit according to the output status of the first operational amplifier module 720.

[0044] It is worth noting that the existing sampling chip 730 and micro control unit do not support negative value sampling. In the case of reverse connection, the voltage difference output by the first operational amplifier module 720 is a negative value. At this time, the sampling chip 730 and the micro control unit cannot obtain the signal, that is, they cannot know whether the battery is not connected or connected reversely. Therefore, this embodiment sets a voltage compensation module 710 and uses the constant voltage of the voltage compensation module 710 as the bias voltage of the operational amplifier to ensure that the output value of the first operational amplifier module 720 is always positive, so that the battery status can be judged and the wiring status can be detected to ensure that other processes proceed smoothly.

[0045] It is understandable that the commonly used DC current sampling methods currently include Hall sensors, shunts, etc. Among them, the advantages of Hall sensors are simple structure and high precision, and the disadvantages are that they are easily affected by magnetic fields, require shielding systems, and are costly. Based on the above advantages and disadvantages, the use of shunts for DC current signal sampling has become the preferred solution for various manufacturers. The advantages of shunts are simple structure, large measurement range, and no influence from external magnetic fields, but the disadvantage is that the shunt is directly connected to the main circuit and is not electrically isolated. Therefore, the existing DC sampling circuit is more complex and the overall cost is also higher. This embodiment can achieve accurate sampling of the battery to be tested while reducing costs by setting the voltage compensation module 710 and the first operational amplifier module 720, so that the battery state and wiring state can be judged, and the AC impedance test can be smoothly carried out, and the accuracy of the impedance spectrum obtained by the impedance detection circuit can be further improved.

[0046] In some embodiments, the controller 200 is used to determine the positive and reverse connection conditions of the battery group 130 to be tested in the impedance detection circuit when there is an output voltage at the output end, thereby realizing the judgment of the positive and reverse connection conditions of the battery to be tested; the controller 200 is also used to determine that the battery group 130 to be tested is not connected to the impedance detection circuit when there is no output voltage at the output end, thereby realizing accurate judgment of the wiring status.

[0047] It should be noted that the first operational amplifier module 720 is connected to the output end of the voltage compensation module 710 at the positive voltage input end. The voltage compensation module 710 includes a constant voltage source, which is connected to the positive phase input end of the first operational amplifier module 720, so that the voltage compensation module 710 can output a bias voltage, thereby ensuring that the output voltage of the output end of the amplifier module is positive. Taking the output of a bias voltage of 1.25V by the voltage compensation module 710 as an example, this embodiment is explained. When the bias voltage is 1.25V, the output voltage Vo of the first operational amplifier module 720 is [1.25+(V+)-(V-)]*100K / 200K. If the input = 0, calculate Vo = 0.625V. When the voltage value sampled by the DC sampling circuit is <0.625V, it means that the battery voltage sampling is a negative value, and the system recognizes and performs battery reverse connection protection. When the DC sampling circuit does not sample normally, it means that the battery undergoing EIS detection is not connected, which makes it easier for the tester to take timely countermeasures. Therefore, in this embodiment, the output value of the first operational amplifier module 720 is always a positive value. The output of the first operational amplifier module 720 can accurately determine the two abnormal situations of not being connected or being connected in reverse, and take corresponding countermeasures in time to avoid invalid testing, thereby saving time and human resources while ensuring the accuracy and reliability of the test results.

[0048] It can be understood that the controller 200 is connected to the output end of the first operational amplifier module 720. When the voltage value sampled by the DC sampling circuit is <0.625V, it means that the battery voltage sample is a negative value. At this time, the controller 200 can determine whether the battery to be tested is connected forwardly or reversely based on the received output voltage value of the first operational amplifier module 720, that is, when the received voltage value is less than 0.625V, it is determined that the battery to be tested is connected reversely, and when the received voltage value is greater than or equal to 0.625V, it is determined that the battery to be tested is connected forwardly; when no signal is received, it is determined that the battery group 130 to be tested is not connected to the impedance detection circuit. Among them, the voltage value of the constant voltage source of the voltage compensation module 710 in this embodiment can be set according to the actual needs of the user, and this embodiment does not make specific restrictions.

[0049] Please refer to Figure 3 , Figure 3 4 is a circuit diagram of the current wave generating module 430 provided in an embodiment of the present application.

[0050] In some embodiments, the current wave generating module 430 includes a Darlington transistor and a current limiting resistor. The Darlington transistor includes a first NPN transistor Q1 and a second NPN transistor Q2. The base of the first NPN transistor Q1 is connected to the impedance measurement chip 420, the emitter of the first NPN transistor Q1 is connected to the sampling resistor 410, the collector of the first NPN transistor Q1 is connected to the base of the second NPN transistor Q2, the emitter of the second NPN transistor Q2 is connected between the emitter of the first NPN transistor Q1 and the sampling resistor 410, and the collector of the second NPN transistor Q2 is connected to the current limiting resistor, thereby amplifying the excitation current, ensuring that the sampling voltage is maintained within the optimal receiving range of the chip when the impedance changes, improving the sensitivity of the test, and improving the efficiency and quality of data acquisition.

[0051] In some embodiments, the DC sampling circuit also includes a circuit board measurement circuit, which is connected to the first operational amplifier module 720. The circuit board measurement circuit is used to measure the voltage across the test board, wherein the test board is connected to the battery pack 130 to be tested via a connecting line, thereby being able to measure the line resistance between the battery to be tested and the test board, thereby realizing the judgment of the wiring condition.

[0052] It should be noted that by measuring the resistance value of the line, the quality and electrical performance of the connecting line can be evaluated, problems in the line can be discovered and dealt with in a timely manner, and the size of the line resistance will affect the quality of signal transmission. Measuring the line resistance can help ensure stable and reliable signal transmission and reduce interference and attenuation.

[0053] In some embodiments, the impedance measurement module also includes an analog-to-digital converter and a discrete Fourier transform unit, wherein the analog-to-digital converter is used to receive a sampling signal to determine impedance data corresponding to the battery to be tested, and the discrete Fourier transform unit is connected to the analog-to-digital converter to perform a discrete Fourier transform on the impedance data, thereby being able to analyze the changes in impedance at different frequencies, remove noise or sudden interference, and improve the quality and accuracy of the data.

[0054] In some embodiments, the impedance measurement module also includes a storage unit, which is connected to the discrete Fourier transform unit to store the target impedance value, thereby realizing the storage of the impedance value, avoiding data loss, and improving the stability of data transmission. The storage unit is also used to send the impedance value to the controller 200, thereby facilitating subsequent analysis of the impedance value and realizing accurate detection of the battery to be tested.

[0055] It can be understood that the impedance measurement module also includes a waveform generator, a high-speed digital-to-analog converter and an excitation buffer connected in sequence, and a sequencer, an oscillator and a discrete Fourier transform unit connected in sequence, wherein the waveform generator is used to generate a signal waveform in a specific form, such as a sine wave, a square wave, a triangle wave, etc., and is also used to generate a signal of a specific frequency and amplitude. The high-speed digital-to-analog converter is used to convert an analog signal into a digital signal, thereby improving the sampling rate and data conversion capability. The excitation buffer is used to enhance the signal and temporarily store the data input by the high-speed digital-to-analog converter. The multiplexer is used to select and output one or more signals from multiple input signals to the analog-to-digital converter, so that the analog-to-digital converter converts the analog signal into a data signal, that is, impedance data, and then sends the impedance data to the discrete Fourier transform unit for processing.

[0056] It should be noted that the sequencer is used to control the working order of each functional module in the circuit, ensure that the signal is processed according to a certain timing, and assist each part in the circuit. The oscillator is used to generate a stable frequency signal to provide a clock signal or a reference signal for subsequent signal processing, so that each part in the circuit can work synchronously and improve the accuracy and stability of signal processing. In this embodiment, the sequencer, oscillator and discrete Fourier transform unit are connected in series to ensure that the signal is processed in the correct order and obtain accurate spectrum analysis results.

[0057] In some embodiments, the impedance measurement module also includes a connected low-power impedance amplifier (TransImpedance Amplifier) ​​and a low-power, dual-output digital-to-analog converter (Low-Power Dual-Output Analog-to-Digital Converter, DAC), wherein the low-power impedance amplifier is used to amplify the impedance of the input signal so that it can adapt to the input end of the subsequent circuit, and can provide a stable amplification factor to ensure signal quality and accuracy, can match the conversion between different impedances, and realize signal transmission and processing. The low-power, dual-output digital-to-analog converter can convert analog signals into digital information, improve dual output channels, and can simultaneously output digital signals of different precisions or different frequencies. In this embodiment, the low-power impedance amplifier and the low-power, dual-output digital-to-analog converter cooperate with each other to effectively reduce the power consumption of the overall circuit, enhance the amplitude of the signal, and improve the flexibility and efficiency of the circuit.

[0058] refer to Figure 4 , Figure 4 It is a schematic diagram of the pluggable terminal provided in the embodiment of the present application.

[0059] In some embodiments, a four-wire wiring method is used in this embodiment, which is simple in wiring and can test loop impedance, wherein V+ / V- is used to measure the voltage at both ends of the battery to be tested, and I+ / I- is used to measure the voltage at the test board end. Figure 2 and Figure 4 The circuits are connected to each other, when Figure 2 The pins in are V+ / V-, Figure 2 and Figure 4 The connection constitutes a sampling circuit for measuring the battery to be tested. Figure 2 The pins are I+ / I-, Figure 2 and Figure 4 The connection is used to form a voltage processing circuit at the measuring board end, so that the controller 200 can judge the state of the battery and detect the wiring condition based on the output condition of the output end of the first operational amplifier module 720, ensuring that other steps proceed smoothly.

[0060] The embodiments described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Those skilled in the art will appreciate that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0061] It can be understood by those skilled in the art that Figures 1 to 4 The technical solutions shown in the specification do not constitute a limitation on the embodiments of the present application.

[0062] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0063] Those skilled in the art will appreciate that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices may be implemented as software, firmware, hardware, or a suitable combination thereof.

[0064] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0065] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0066] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. An EIS detection circuit based on DC sampling, characterized in that: include: An impedance detection circuit, comprising a first terminal and a second terminal for connecting to a battery pack to be tested; A DC sampling circuit includes a voltage compensation module and a first operational amplifier module, wherein the non-inverting input terminal of the first operational amplifier module is connected to the first terminal, and the inverting input terminal is connected to the second terminal, the voltage compensation module is connected to the non-inverting input terminal of the first operational amplifier module, and the output terminal of the first operational amplifier module is connected to the controller of the impedance detection circuit so that the controller determines the connection status of the battery pack to be tested in the impedance detection circuit, wherein the constant voltage of the voltage compensation module is greater than the battery voltage of the battery pack to be tested.

2. The EIS detection circuit according to claim 1, characterized in that: The DC sampling circuit also includes a sampling chip, which is connected to the output end of the first operational amplifier module. The sampling chip is connected to the controller so that the controller determines the connection status of the battery pack to be tested in the impedance detection circuit.

3. The EIS detection circuit according to claim 1, characterized in that: The impedance detection circuit includes an impedance measurement module and a sampling resistor, the sampling resistor is connected to the battery pack to be tested, and the impedance measurement module is used to sample the instantaneous voltage across the sampling resistor or the instantaneous voltage across the battery to be tested in the battery pack to be tested.

4. The EIS detection circuit according to claim 3, characterized in that: The impedance measurement module includes an impedance measurement chip, a current wave generation module and a signal detection module; the current wave generation module is connected to the impedance measurement chip to amplify the excitation current output by the impedance measurement chip, the signal detection module is used to connect the battery pack to be tested or the branch where the sampling resistor is located, and the impedance measurement chip is connected to the signal detection module to determine the impedance value of the battery pack to be tested.

5. The EIS detection circuit according to claim 4, characterized in that: The signal detection module includes an analog switch and a second operational amplifier module, the analog switch is connected to the sampling resistor and the battery pack to be tested respectively, the controller is also used to send a selection signal, the signal detection module is used to receive the selection signal to connect the battery to be tested or the branch where the sampling resistor is located through the analog switch, and the second operational amplifier module is connected to the analog switch to amplify the sampling signal output by the signal detection module.

6. The EIS detection circuit according to claim 5, characterized in that: The impedance measurement module also includes an analog-to-digital converter and a discrete Fourier transform unit. The analog-to-digital converter is used to receive the sampling signal to determine the impedance data corresponding to the battery to be tested. The discrete Fourier transform unit is connected to the analog-to-digital converter to perform discrete Fourier transform on the impedance data.

7. The EIS detection circuit according to claim 6, characterized in that: The impedance measurement module further includes a storage unit connected to the discrete Fourier transform unit to store the impedance value.

8. The EIS detection circuit according to claim 4, characterized in that: The current wave generating module includes a Darlington transistor and a current limiting resistor. The Darlington transistor includes a first NPN transistor and a second NPN transistor. The base of the first NPN transistor is connected to the impedance measurement chip, the emitter of the first NPN transistor is connected to the sampling resistor, the collector of the first NPN transistor is connected to the base of the second NPN transistor, the emitter of the second NPN transistor is connected between the emitter of the first NPN transistor and the sampling resistor, and the collector of the second NPN transistor is connected to the current limiting resistor.

9. The EIS detection circuit according to claim 1, characterized in that: The voltage compensation module includes a constant voltage source, and the constant voltage source is connected to the non-inverting input terminal of the first operational amplifier module.

10. The EIS detection circuit according to any one of claims 1 to 9, characterized in that: The DC sampling circuit also includes a circuit board measurement circuit, which is connected to the first operational amplifier module and is used to measure the voltage across a test board, wherein the test board is connected to the battery pack to be tested via a connecting line.

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