A detection circuit for battery electrochemical impedance spectrum

Abstract

The application provides a detection circuit of a battery electrochemical impedance spectrum, an input end of a resonant circuit is connected with a positive electrode of a battery to be detected, an output end of the resonant circuit and an input end of a battery management module are connected with a negative electrode of the battery to be detected, and an output end of the battery management module is connected with the input end of the resonant circuit; a first end of an inductor is connected with the positive electrode of the battery to be detected, a first end of a capacitor and a drain of a first switch tube are connected with a second end of the inductor, a second end of the capacitor is connected with a drain of a second switch tube, a source of the second switch tube is connected with the negative electrode of the battery to be detected, a source of the first switch tube is connected with the drain of the second switch tube, and a gate of the first switch tube and a gate of the second switch tube are connected with the output end of the battery management module. The online detection of the electrochemical impedance spectrum is realized in the normal charging and discharging process of the battery to be detected, and the convenience of detection is greatly improved.

Description

Technical Field

[0001] This application relates to the field of battery detection technology, and more specifically, to a detection circuit for battery electrochemical impedance spectroscopy. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS), as an important electrochemical analysis method, is widely used in battery performance evaluation and state monitoring. This method effectively characterizes key parameters within a battery, such as internal resistance, double-layer capacitance, and Faraday impedance, by applying a small-amplitude sinusoidal AC signal to the battery system and measuring its response.

[0003] Traditional EIS detection circuits typically employ an architecture that connects a power excitation resistor, a MOSFET, and a current sampling circuit between the positive and negative terminals of the battery. The processor generates a swept-frequency sinusoidal signal to drive the MOSFET, causing the excitation circuit to produce a frequency-adjustable sinusoidal alternating current. Simultaneously, by acquiring the loop current and cell terminal voltage signals, the impedance spectrum characteristics of the battery are calculated. However, this conventional approach has significant technical drawbacks: the power excitation resistor continuously consumes a large amount of energy, leading to reduced system energy efficiency; furthermore, the processor must handle the complex tasks of sinusoidal signal generation and synchronous acquisition, making the control algorithm implementation quite challenging. Utility Model Content

[0004] In view of this, the purpose of this application is to provide a detection circuit for battery electrochemical impedance spectroscopy, which can realize the oscillation of the resonant circuit by controlling the conduction and disconnection of the first switching transistor through the battery management module, so as to realize online detection of electrochemical impedance spectroscopy during the normal charging and discharging process of the battery under test, which greatly improves the convenience of detection, improves the purity of the signal, and thus significantly improves the accuracy of impedance measurement.

[0005] This application provides a detection circuit for battery electrochemical impedance spectroscopy. The detection circuit includes a battery management module and a resonant circuit. The resonant circuit includes an inductor, a capacitor, a first switching transistor, and a second switching transistor. The input terminal of the resonant circuit is connected to the positive terminal of the battery under test, and the output terminal of the resonant circuit and the input terminal of the battery management module are both connected to the negative terminal of the battery under test. The output terminal of the battery management module is connected to the input terminal of the resonant circuit. The first end of the inductor is connected to the positive terminal of the battery under test. The first end of the capacitor and the drain of the first switching transistor are both connected to the second end of the inductor. The second end of the capacitor is connected to the drain of the second switching transistor. The source of the second switching transistor is connected to the negative terminal of the battery under test. The source of the first switching transistor is connected to the drain of the second switching transistor. The gates of the first switching transistor and the second switching transistor are both connected to the output terminal of the battery management module. The battery management module controls the on and off states of the first switching transistor to generate an AC sine wave signal in the resonant circuit, and the impedance spectrum of the battery under test is determined based on the AC sine wave signal.

[0006] Furthermore, the resonant circuit also includes a first isolation driving circuit and a second isolation driving circuit. The first isolation driving circuit is used to drive the first switch to turn on and off, and the second isolation driving circuit is used to drive the second switch to turn on and off. The input terminal of the first isolation drive circuit is connected to the output terminal of the battery management module, the output terminal of the first isolation drive circuit is connected to the gate of the first switching transistor, the input terminal of the second isolation drive circuit is connected to the output terminal of the battery management module, and the output terminal of the second isolation drive circuit is connected to the gate of the second switching transistor. The battery management module simultaneously inputs a high level to the first isolation drive circuit and the second isolation drive circuit according to a preset resonance period, so that both the first switch and the second switch are closed, and the current of the battery under test flows through the positive terminal of the battery to the capacitor and the inductor to charge the capacitor and the inductor. When the high level of the first isolation drive circuit reaches the preset duty cycle, the battery management module inputs a low level to the first isolation drive circuit to turn off the first switch, and the current continues to charge the capacitor and the inductor. When the capacitor and the inductor are fully charged, the voltage of the capacitor increases, and the current flows back to the positive terminal of the battery under test. The second isolation drive circuit realizes the electrical isolation between the battery management module and the second switch.

[0007] Furthermore, the resonant circuit also includes a freewheeling circuit, which forms the energy release circuit of the resonant circuit. The first end of the freewheeling circuit is connected to the first end of the inductor, and the second end of the freewheeling circuit is connected to the second end of the capacitor. At the end of the impedance spectrum detection, the battery management module simultaneously inputs a low level to the first isolation drive circuit and the second isolation drive circuit, so that the first switch and the second switch are both turned off. The current inside the resonant circuit flows from the capacitor to the inductor and the freewheeling circuit in sequence, and then flows from the freewheeling circuit to the capacitor to consume the electrical energy inside the resonant circuit.

[0008] Furthermore, the battery management module includes a processor unit, a voltage acquisition unit, and a current sampling circuit. The voltage acquisition unit is used to detect the voltage of the battery under test, the current sampling circuit is used to detect the current of the battery under test, and the processor unit is used to determine the impedance of the battery under test. The input terminal of the voltage acquisition unit is connected to the negative terminal of the battery to be tested, and the output terminal of the voltage acquisition unit is connected to the input terminal of the processor unit. The input terminal of the current sampling circuit is connected to the negative terminal of the battery to be tested, and the output terminal of the current sampling circuit is connected to the input terminal of the processor unit.

[0009] Furthermore, the detection circuit also includes an interface circuit. The positive terminal of the battery under test is coupled to the first input terminal of the interface circuit. The input terminal of the resonant circuit is coupled to the first output terminal of the interface circuit. The output terminal of the resonant circuit is coupled to the second input terminal of the interface circuit. The negative terminal of the battery under test is coupled to the second output terminal of the interface circuit. The input terminal of the battery management module is coupled to the third input terminal of the interface circuit. The gate of the first switching transistor is coupled to the third output terminal of the interface circuit. The gate of the second switching transistor is coupled to the fourth output terminal of the interface circuit.

[0010] Furthermore, the capacitor is a capacitor bank consisting of a large-value capacitor and a small-value capacitor connected in parallel.

[0011] Furthermore, the capacitance of the large-value capacitor is 100uF-10mF, and the capacitance of the small-value capacitor is 1nF-10uF.

[0012] Furthermore, the inductor is a pre-biased, high-value inductor.

[0013] Furthermore, the inductance value of the pre-biased large-value inductor is in the range of 5uH-1mH.

[0014] Furthermore, the battery to be tested is any one of lithium battery, fuel cell, lead-acid battery, sodium-ion battery, and nickel-metal hydride battery.

[0015] This application provides a detection circuit for the electrochemical impedance spectroscopy of a battery, including a battery management module and a resonant circuit. The resonant circuit includes an inductor, a capacitor, a first switching transistor, and a second switching transistor. The input terminal of the resonant circuit is connected to the positive terminal of the battery under test. The output terminal of the resonant circuit and the input terminal of the battery management module are both connected to the negative terminal of the battery under test, and the output terminal of the battery management module is connected to the input terminal of the resonant circuit. The first terminal of the inductor is connected to the positive terminal of the battery under test. The first terminal of the capacitor and the drain of the first switching transistor are both connected to the second terminal of the inductor. The second terminal of the capacitor is connected to the drain of the second switching transistor. The source of the second switching transistor is connected to the negative terminal of the battery under test. The source of the first switching transistor is connected to the drain of the second switching transistor. The gates of the first and second switching transistors are both connected to the output terminal of the battery management module. The battery management module controls the on / off state of the first switching transistor to generate an AC sine wave signal in the resonant circuit, and the impedance spectrum of the battery under test is determined based on the AC sine wave signal.

[0016] This application integrates a resonant circuit into the battery management module, eliminating the need for an external power supply or load device. Utilizing the characteristics of the resonant circuit, the battery management module does not need to generate a sweeping sinusoidal signal; simply controlling the on / off state of the first switching transistor via the battery management module is sufficient to achieve oscillation of the resonant circuit. This generates an AC sinusoidal signal, enabling online detection of electrochemical impedance spectroscopy during the normal charging and discharging process of the battery under test, significantly improving the convenience and practicality of the detection. Compared to the traditional MOS-driven resistor excitation method, this application can excite the resonant circuit oscillation by simply controlling the first switching transistor with a pulse drive. The resonant circuit generates a standard sinusoidal current, without introducing an external power supply impedance signal, avoiding noise and interference introduced by additional excitation sources, improving signal purity, and thus significantly improving the accuracy of impedance measurement.

[0017] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is one of the schematic diagrams of a detection circuit for battery electrochemical impedance spectroscopy provided in an embodiment of this application; Figure 2 This is a second schematic diagram of the structure of a detection circuit for battery electrochemical impedance spectroscopy provided in an embodiment of this application; Figure 3 This is a schematic diagram of a voltage waveform provided in an embodiment of this application; Figure 4 This is a schematic diagram of a current waveform provided in an embodiment of this application; Figure 5 This application provides a schematic diagram of a voltage and current combination waveform.

[0020] Referring to the accompanying drawings, the reference numerals in the embodiments of this application are as follows: 100 - Detection circuit; 110 - Battery management module; 120 - Resonant circuit; 121 - Inductor; 122 - Capacitor; 123 - First switching transistor; 124 - Second switching transistor; 125 - First isolation drive circuit; 126 - Second isolation drive circuit; 127 - Freewheeling circuit; 111 - Processor unit; 112 - Voltage acquisition unit; 113 - Current sampling circuit; 130 - Interface circuit. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments of this application, every other embodiment obtained by those skilled in the art without inventive effort falls within the scope of protection of this application.

[0022] In the description of the embodiments of this application, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0023] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0024] In the description of the embodiments of this application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0025] To enable those skilled in the art to use the content of this application and in conjunction with the specific application scenario of "electrochemical impedance spectroscopy detection of the battery under test", the following implementation method is provided. For those skilled in the art, the general principles defined herein can be applied to other embodiments and application scenarios without departing from the spirit and scope of this application.

[0026] Electrochemical impedance spectroscopy (EIS), as an important electrochemical analysis method, is widely used in battery performance evaluation and state monitoring. This method effectively characterizes key parameters within a battery, such as internal resistance, double-layer capacitance, and Faraday impedance, by applying a small-amplitude sinusoidal AC signal to the battery system and measuring its response.

[0027] Research has revealed that traditional EIS detection circuits typically employ an architecture connecting a power excitation resistor, a MOSFET, and a current sampling circuit between the positive and negative terminals of the battery. The processor generates a swept-frequency sinusoidal signal to drive the MOSFET, causing the excitation circuit to produce a frequency-adjustable sinusoidal alternating current. Simultaneously, by acquiring the loop current and cell terminal voltage signals, the battery's impedance spectrum characteristics are calculated. However, this conventional approach has significant technical drawbacks: the power excitation resistor continuously consumes a large amount of energy, leading to reduced system energy efficiency; furthermore, the processor must handle the complex tasks of sinusoidal signal generation and synchronous acquisition, making the control algorithm implementation quite challenging.

[0028] Based on this, the embodiments of this application provide a detection circuit for battery electrochemical impedance spectroscopy. The oscillation of the resonant circuit can be achieved by controlling the conduction and disconnection of the first switching transistor through the battery management module. This enables online detection of electrochemical impedance spectroscopy during the normal charging and discharging process of the battery under test, greatly improving the convenience of detection, increasing the purity of the signal, and thus significantly improving the accuracy of impedance measurement.

[0029] Please see Figure 1 , Figure 1 This is one of the schematic diagrams of a detection circuit for battery electrochemical impedance spectroscopy provided in an embodiment of this application. Figure 1 As shown in the figure, the detection circuit 100 provided in this application embodiment includes: a battery management module 110 and a resonant circuit 120. The resonant circuit 120 is provided with an inductor 121, a capacitor 122, a first switching transistor 123 and a second switching transistor 124.

[0030] Specifically, the input terminal of the resonant circuit 120 is connected to the positive terminal of the battery under test, the output terminal of the resonant circuit 120 and the input terminal of the battery management module 110 are both connected to the negative terminal of the battery under test, and the output terminal of the battery management module 110 is connected to the input terminal of the resonant circuit 120.

[0031] The first terminal of the inductor 121 is connected to the positive terminal of the battery under test. The first terminal of the capacitor 122 and the drain of the first switching transistor 123 are both connected to the second terminal of the inductor 121. The second terminal of the capacitor 122 is connected to the drain of the second switching transistor 124. The source of the second switching transistor 124 is connected to the negative terminal of the battery under test. The source of the first switching transistor 123 is connected to the drain of the second switching transistor 124. The gates of the first switching transistor 123 and the second switching transistor 124 are both connected to the output terminal of the battery management module 110. By controlling the on and off states of the first switching transistor 123 through the battery management module 110, the resonant circuit 120 generates an AC sine wave signal. The battery management module 110 can then determine the impedance spectrum of the battery under test based on the AC sine wave signal.

[0032] Specifically, the battery to be tested is any one of lithium battery, fuel cell, lead-acid battery, sodium-ion battery, and nickel-metal hydride battery.

[0033] Please see Figure 2 , Figure 2 This is a second schematic diagram of a detection circuit for battery electrochemical impedance spectroscopy provided in an embodiment of this application. Figure 2As shown, the resonant circuit 120 further includes a first isolation driving circuit 125 and a second isolation driving circuit 126. The first isolation driving circuit 125 is used to drive the first switching transistor 123 to turn on and off, and the second isolation driving circuit 126 is used to drive the second switching transistor 124 to turn on and off.

[0034] Specifically, the input terminal of the first isolation drive circuit 125 is connected to the output terminal of the battery management module 110, the output terminal of the first isolation drive circuit 125 is connected to the gate of the first switch 123, the input terminal of the second isolation drive circuit 126 is connected to the output terminal of the battery management module 110, and the output terminal of the second isolation drive circuit 126 is connected to the gate of the second switch 124.

[0035] Here, both the first isolation drive circuit 125 and the second isolation drive circuit 126 are drive circuits with electrical isolation functions, and common forms include optocoupler isolation, magnetic coupling isolation or capacitive isolation.

[0036] The battery management module 110 simultaneously inputs a high level to the first isolation drive circuit 125 and the second isolation drive circuit 126 according to a preset resonance period, so that the first switch 123 and the second switch 124 are both closed, and the current of the battery under test flows through the positive terminal of the battery to the capacitor 122 and the inductor 121 to charge the capacitor 122 and the inductor 121.

[0037] Here, the preset resonance period is the time required for the resonant circuit 120 to complete one full oscillation cycle when resonance occurs. Specifically, the preset resonance period is calculated using the resonant frequency f of the resonant circuit 120. For example, if we want to detect the resistance of the battery under test at a resonant frequency of 10kHz, we need to adjust the values ​​of inductor 121 and capacitor 122 to make the resonant frequency f of the resonant circuit 120 reach 10kHz, and at the same time determine the preset resonance period. The first switch 123 is the active switch in the resonant circuit 120. Its conduction and disconnection are controlled by the high and low levels output by the battery management module 110, and it is used to start and maintain the resonance of the resonant circuit 120. When the first switch 123 is turned on, it charges the resonant circuit 120, and the second switch 124 remains on to form a loop.

[0038] When the high level of the first isolation drive circuit 125 reaches the preset duty cycle, the battery management module 110 inputs a low level to the first isolation drive circuit 125, causing the first switch 123 to turn off, and the current continues to charge the inductor 121 and the capacitor 122. When the inductor 121 and the capacitor 122 are fully charged, the voltage of the capacitor 122 increases, and the current flows back to the positive terminal of the battery under test. The second isolation drive circuit 126 realizes the electrical isolation between the battery management module 110 and the second switch 124.

[0039] Here, when the high level of the first isolation drive circuit 125 is maintained for a certain duty cycle, reaching a preset duty cycle, such as 50%, the battery management module 110 inputs a low level to the first isolation drive circuit 125, causing the first switch 123 to turn off. After the first switch 123 is turned off, it no longer participates in the subsequent resonance process. The current continues to charge the capacitor 122 and inductor 121 in the resonant circuit 120. After the resonant circuit 120 is fully charged, it continues to oscillate freely by relying on its own stored energy. The positive voltage of the capacitor 122 increases, and the current will flow back to the positive terminal of the battery under test. The resonant circuit 120 begins to discharge and oscillate to form a sinusoidal current. As the reverse current decreases, the amplitude of the sinusoidal current will gradually decrease until it disappears. In this process, the overall current direction is divided into two segments: forward and reverse. Forward: the current flows sequentially from the positive terminal of the battery under test to inductor 121, capacitor 122, second switch 124, and the negative terminal of the battery under test, finally returning to the positive terminal of the battery under test to form a loop. Reverse: the current flows sequentially from capacitor 122 to inductor 121, the positive terminal of the battery under test, the negative terminal of the battery under test, and the second switch 124, finally returning to capacitor 122 to form a loop. The change from forward to reverse current is the process of the sinusoidal current direction changing from positive to negative. Simultaneously, this application utilizes the characteristics of the resonant circuit 120, allowing the high-voltage current generated during the excitation process to flow back into the battery under test, achieving partial energy recovery and effectively reducing overall energy loss. Furthermore, to prevent high voltage feedback to the battery management module 110 during current backflow, an isolation drive circuit is set in the resonant circuit 120 to achieve electrical isolation.

[0040] Specifically, the formula for calculating the resonant frequency of resonant circuit 120 is as follows:

[0041] in, The resonant frequency, The inductance value of inductor 121, This refers to the capacitance value of a 122 capacitor. Different combinations of inductance and capacitance values ​​yield different resonant frequencies. Resonant frequency. With angular frequency The relationship is: The angular frequency of the excitation signal can be obtained through conversion. Please see. Figures 3-5 , Figure 3 This is a schematic diagram of a voltage waveform provided in an embodiment of this application. Figure 4 This is a schematic diagram of a current waveform provided in an embodiment of this application. Figure 5 This application provides a schematic diagram of a voltage and current combined waveform. When the resonant circuit 120 oscillates, the resulting voltage and current waveforms are as follows: Figures 3-5 As shown.

[0042] After the current preset resonant period ends, if continuous frequency sweep excitation is required, the battery management module 110 will periodically send high and low levels to the first isolation drive circuit 125 according to the set frequency to control the on and off of the first switch transistor 123, thereby maintaining impedance spectrum measurements at multiple frequency points. After the resistance test at the current resonant frequency is completed, the values ​​of inductor 121 and capacitor 122 are changed to change the resonant frequency, and the battery electrochemical impedance spectrum test at the next resonant frequency is performed.

[0043] For further details, please refer to Figure 2 The resonant circuit 120 further includes a freewheeling circuit 127, which forms an energy release circuit for the resonant circuit 120. Specifically, the first end of the freewheeling circuit 127 is connected to the first end of the inductor 121, and the second end of the freewheeling circuit 127 is connected to the second end of the capacitor 122.

[0044] Here, after both the first switch 123 and the second switch 124 are turned off, the freewheeling circuit 127 provides a low-impedance path for the current to continue flowing, preventing voltage spikes or energy oscillations caused by sudden current changes.

[0045] Specifically, at the end of impedance spectrum detection, the battery management module 110 simultaneously inputs a low level to the first isolation drive circuit 125 and the second isolation drive circuit 126, so that the first switch 123 and the second switch 124 are both turned off. The current inside the resonant circuit 120 flows from the capacitor 122 to the inductor 121 and the freewheeling circuit 127 in sequence, and then from the freewheeling circuit 127 to the capacitor 122, so as to consume the electrical energy inside the resonant circuit 120.

[0046] Here, at the completion of the entire EIS excitation process, i.e., when the frequency sweep measurement ends, the resonance of the resonant circuit 120 completely stops. The battery management module 110 actively shuts down the first switch 123 and the second switch 124 to cut off the energy cycle of the resonant circuit 120. At this time, the freewheeling circuit 127 provides a path for releasing the remaining electrical energy inside the resonant circuit 120. The remaining electrical energy in the resonant circuit 120 will be exhausted through the freewheeling circuit 127 to ensure the safe shutdown of the resonant circuit 120.

[0047] For further details, please refer to Figure 2 The battery management module 110 includes a processor unit 111, a voltage acquisition unit 112, and a current sampling circuit 113.

[0048] Specifically, the voltage acquisition unit 112 is used to detect the voltage of the battery under test, the current sampling circuit 113 is used to detect the current of the battery under test, and the processor unit 111 is used to determine the impedance of the battery under test.

[0049] The input terminal of the voltage acquisition unit 112 is connected to the negative terminal of the battery under test, and the output terminal of the voltage acquisition unit 112 is connected to the input terminal of the processor unit 111. The input terminal of the current sampling circuit 113 is connected to the negative terminal of the battery under test, and the output terminal of the current sampling circuit 113 is connected to the input terminal of the processor unit 111.

[0050] Specifically, the angular frequency of the excitation signal, For the excitation current signal, In response to a voltage signal, the ratio of the response voltage to the excitation current is the impedance at that resonant frequency, according to the following formula: This represents the internal impedance of the battery, where Vm and Im are the voltage and current amplitudes, respectively. The initial phase angle of the current. By continuously changing the angular frequency of the excitation current. The wideband impedance characteristics of the battery are obtained. The impedance calculation formula is:

[0051] and The following complex function can be used for modification:

[0052] The above impedance calculation formula can then be rewritten as:

[0053] By Euler's formula The above formula can be simplified to:

[0054] Thus, when the resonant circuit 120 oscillates, the voltage acquisition unit 112 is connected to the negative terminal of the battery under test, and the voltage of the battery under test is determined by the voltage waveform. The current sampling circuit 113 is connected to the negative terminal of the battery under test, and determines the current of the battery under test by the current waveform. The voltage acquisition unit 112 sends the detected voltage to the processor unit 111, and the current sampling circuit 113 sends the detected current to the processor unit 111. The processor unit 111 can then calculate the impedance of the battery under test using the above formula.

[0055] For further details, please refer to Figure 2 The detection circuit 100 further includes an interface circuit 130. Here, the interface circuit 130 refers to the electrical connection involved in signal or energy transfer between two modules, and is the core unit in the detection circuit 100 that enables information interaction between different components. The interface circuit 130 includes multiple input terminals and multiple output terminals. Specifically, the positive terminal of the battery under test is coupled to the first input terminal of the interface circuit 130, the input terminal of the resonant circuit 120 is coupled to the first output terminal of the interface circuit 130, the output terminal of the resonant circuit 120 is coupled to the second input terminal of the interface circuit 130, the negative terminal of the battery under test is coupled to the second output terminal of the interface circuit 130, the input terminal of the battery management module 110 is coupled to the third input terminal of the interface circuit 130, the gate of the first switching transistor 123 is coupled to the third output terminal of the interface circuit 130, and the gate of the second switching transistor 124 is coupled to the fourth output terminal of the interface circuit 130.

[0056] As an optional embodiment, capacitor 122 is a capacitor bank consisting of a large-value capacitor and a small-value capacitor connected in parallel. Specifically, the large-value capacitor has a capacitance of 100uF-10mF, and the small-value capacitor has a capacitance of 1nF-10uF.

[0057] As an optional embodiment, the inductor 121 is a pre-biased high-value inductor. Specifically, the inductance value of the pre-biased high-value inductor ranges from 5uH to 1mH.

[0058] In this way, by configuring combinations of inductors 121 and capacitors 122 with different parameters, frequency scanning in the range of 20Hz to 10kHz can be achieved, covering the main frequency range required for impedance spectrum detection. This helps to comprehensively obtain the dynamic impedance information of the battery under test, providing strong data support for subsequent battery status assessment, health prediction and safety warning.

[0059] This application provides a battery electrochemical impedance spectroscopy detection circuit 100, including a battery management module 110 and a resonant circuit 120. The resonant circuit 120 includes an inductor 121, a capacitor 122, a first switching transistor 123, and a second switching transistor 124. The input terminal of the resonant circuit 120 is connected to the positive terminal of the battery under test. The output terminal of the resonant circuit 120 and the input terminal of the battery management module 110 are both connected to the negative terminal of the battery under test. The output terminal of the battery management module 110 is connected to the input terminal of the resonant circuit 120. The first terminal of the inductor 121 is connected to the positive terminal of the battery under test, and the first terminal of the capacitor 122 and the... The drain of the first switching transistor 123 is connected to the second terminal of the inductor 121. The second terminal of the capacitor 122 is connected to the drain of the second switching transistor 124. The source of the second switching transistor 124 is connected to the negative terminal of the battery under test. The source of the first switching transistor 123 is connected to the drain of the second switching transistor 124. The gates of the first switching transistor 123 and the second switching transistor 124 are both connected to the output terminal of the battery management module 110. The battery management module 110 controls the on and off states of the first switching transistor 123 to generate an AC sine wave signal in the resonant circuit 120, and determines the impedance spectrum of the battery under test based on the AC sine wave signal.

[0060] This application integrates a resonant circuit 120 onto the battery management module 110, eliminating the need for an external power supply or load device. Utilizing the characteristics of the resonant circuit 120, the battery management module 110 does not need to generate a sweeping sinusoidal signal; it only needs to control the on / off state of the first switching transistor 123 to achieve oscillation of the resonant circuit 120, thereby generating an AC sinusoidal signal. This enables online detection of electrochemical impedance spectroscopy during the normal charging and discharging process of the battery under test, greatly improving the convenience and practicality of the detection. Compared to the traditional MOS-driven resistor excitation method, this application can excite the resonant circuit 120 to oscillate through simple pulse drive control of the first switching transistor 123. The resonant circuit 120 generates a standard sinusoidal current, without introducing an external power supply impedance signal, avoiding noise and interference introduced by an additional excitation source, improving signal purity, and thus significantly improving the accuracy of impedance measurement.

[0061] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and devices described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division; in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the displayed or discussed mutual coupling or direct coupling or communication connection may be through some communication interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0062] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0063] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0064] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0065] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A detection circuit for electrochemical impedance spectroscopy of a battery, characterized by, The detection circuit includes a battery management module and a resonant circuit, wherein the resonant circuit comprises an inductor, a capacitor, a first switching transistor, and a second switching transistor; wherein... The input terminal of the resonant circuit is connected to the positive terminal of the battery under test, and the output terminal of the resonant circuit and the input terminal of the battery management module are both connected to the negative terminal of the battery under test. The output terminal of the battery management module is connected to the input terminal of the resonant circuit. The first end of the inductor is connected to the positive terminal of the battery under test. The first end of the capacitor and the drain of the first switching transistor are both connected to the second end of the inductor. The second end of the capacitor is connected to the drain of the second switching transistor. The source of the second switching transistor is connected to the negative terminal of the battery under test. The source of the first switching transistor is connected to the drain of the second switching transistor. The gates of the first switching transistor and the second switching transistor are both connected to the output terminal of the battery management module. The battery management module controls the on and off states of the first switching transistor to generate an AC sine wave signal in the resonant circuit, and the impedance spectrum of the battery under test is determined based on the AC sine wave signal.

2. The detection circuit of claim 1, wherein, The resonant circuit further includes a first isolation driving circuit and a second isolation driving circuit. The first isolation driving circuit is used to drive the first switch to turn on and off, and the second isolation driving circuit is used to drive the second switch to turn on and off. The input terminal of the first isolation drive circuit is connected to the output terminal of the battery management module, the output terminal of the first isolation drive circuit is connected to the gate of the first switching transistor, the input terminal of the second isolation drive circuit is connected to the output terminal of the battery management module, and the output terminal of the second isolation drive circuit is connected to the gate of the second switching transistor. The battery management module simultaneously inputs a high level to the first isolation drive circuit and the second isolation drive circuit according to a preset resonance period, so that both the first switch and the second switch are closed, and the current of the battery under test flows through the positive terminal of the battery to the capacitor and the inductor to charge the capacitor and the inductor. When the high level of the first isolation drive circuit reaches the preset duty cycle, the battery management module inputs a low level to the first isolation drive circuit to turn off the first switch, and the current continues to charge the capacitor and the inductor. When the capacitor and the inductor are fully charged, the voltage of the capacitor increases, and the current flows back to the positive terminal of the battery under test. The second isolation drive circuit realizes the electrical isolation between the battery management module and the second switch.

3. The detection circuit according to claim 2, characterized in that, The resonant circuit also includes a freewheeling circuit, which forms an energy release circuit for the resonant circuit. The first end of the freewheeling circuit is connected to the first end of the inductor, and the second end of the freewheeling circuit is connected to the second end of the capacitor. At the end of the impedance spectrum detection, the battery management module simultaneously inputs a low level to the first isolation drive circuit and the second isolation drive circuit, so that the first switch and the second switch are both turned off. The current inside the resonant circuit flows from the capacitor to the inductor and the freewheeling circuit in sequence, and then flows from the freewheeling circuit to the capacitor to consume the electrical energy inside the resonant circuit.

4. The detection circuit according to claim 1, characterized in that, The battery management module includes a processor unit, a voltage acquisition unit, and a current sampling circuit. The voltage acquisition unit is used to detect the voltage of the battery under test, the current sampling circuit is used to detect the current of the battery under test, and the processor unit is used to determine the impedance of the battery under test. The input terminal of the voltage acquisition unit is connected to the negative terminal of the battery to be tested, and the output terminal of the voltage acquisition unit is connected to the input terminal of the processor unit. The input terminal of the current sampling circuit is connected to the negative terminal of the battery to be tested, and the output terminal of the current sampling circuit is connected to the input terminal of the processor unit.

5. The detection circuit according to claim 1, characterized in that, The detection circuit further includes an interface circuit. The positive terminal of the battery under test is coupled to the first input terminal of the interface circuit. The input terminal of the resonant circuit is coupled to the first output terminal of the interface circuit. The output terminal of the resonant circuit is coupled to the second input terminal of the interface circuit. The negative terminal of the battery under test is coupled to the second output terminal of the interface circuit. The input terminal of the battery management module is coupled to the third input terminal of the interface circuit. The gate of the first switching transistor is coupled to the third output terminal of the interface circuit. The gate of the second switching transistor is coupled to the fourth output terminal of the interface circuit.

6. The detection circuit according to claim 1, characterized in that, The capacitor is a capacitor bank consisting of a large-value capacitor and a small-value capacitor connected in parallel.

7. The detection circuit according to claim 6, characterized in that, The capacitance of the large-capacitance capacitor is 100uF-10mF, and the capacitance of the small-capacitance capacitor is 1nF-10uF.

8. The detection circuit according to claim 1, characterized in that, The inductor is a pre-biased, high-value inductor.

9. The detection circuit according to claim 8, characterized in that, The inductance range of the pre-biased large-value inductor is 5uH-1mH.

10. The detection circuit according to claim 1, characterized in that, The battery to be tested is any one of lithium battery, fuel cell, lead-acid battery, sodium-ion battery, and nickel-metal hydride battery.

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