Monitoring device, battery system and electric equipment

Abstract

The invention provides a monitoring device, a battery system and electric equipment. The monitoring device disclosed by the invention is used for monitoring a battery or a battery pack, and comprises a voltage monitoring circuit which is used for being connected between a positive electrode and a negative electrode of the battery or the battery pack; the current driving circuit is used for being connected between the positive electrode and the negative electrode of the battery or the battery pack, the current driving circuit can generate driving current, and the driving current can flow in from the negative electrode of the battery or the battery pack and flow out from the positive electrode of the battery or the battery pack; the voltage monitoring circuit is at least used for monitoring AC response voltage caused by the driving current between the positive electrode and the negative electrode when the current driving circuit generates the driving current.

Description

Technical Field

[0001] The present disclosure relates to the technical field of batteries, and in particular to a monitoring device, a battery system, and an electrical device. Background Art

[0002] Batteries or battery packs are the core energy units in products such as electric vehicles, energy storage systems, and portable electronic devices. Their performance degradation and aging directly impact system safety, endurance, and service life. Therefore, real-time monitoring of battery status, particularly accurate assessment of its state of health (SOH), has become a key technology in battery management systems (BMS).

[0003] Currently, commonly used battery state monitoring methods primarily include voltage detection, current integration, temperature monitoring, and model-based estimation algorithms. These methods can, to a certain extent, reflect the battery's state of charge (SOC) and usage, but they have significant limitations in assessing the extent of internal battery aging. For example, during battery cycling, irreversible changes such as electrode material degradation, electrolyte decomposition, and increased internal resistance may occur. These changes often manifest as slow, nonlinear shifts in voltage and current signals, making them difficult to directly identify using conventional parameters.

[0004] These methods generally suffer from low measurement accuracy, susceptibility to interference from operating conditions, and poor repeatability. Especially when the battery is charging or discharging, the high-amplitude current fluctuations and electromagnetic noise in the system severely affect the extraction of weak response signals. As a result, measurement results are significantly affected by the battery's DC bias voltage, resulting in a low signal-to-noise ratio and making stable and reliable battery monitoring difficult.

[0005] Therefore, how to achieve high-precision, anti-interference, and repeatable monitoring of battery status without affecting the normal operation of the battery is a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0006] According to one aspect of the present disclosure, there is provided a monitoring device for monitoring a battery or a battery pack, comprising: a voltage monitoring circuit, the voltage monitoring circuit being connected between the positive electrode and the negative electrode of the battery or battery pack; a current driving circuit, the current driving circuit being configured to be connected between the positive electrode and the negative electrode of the battery or battery pack, the current driving circuit being capable of generating a driving current that can flow from the negative electrode of the battery or battery pack and flow out from the positive electrode of the battery or battery pack; The voltage monitoring circuit is at least used for monitoring an AC response voltage between the positive electrode and the negative electrode caused by the driving current when the current driving circuit generates the driving current.

[0007] According to at least one embodiment of the present disclosure, the monitoring device further includes: A modulation circuit, wherein the modulation circuit is used to generate a current control signal, the modulation frequency of the modulation circuit is a first frequency, thereby generating a current control signal with a frequency of the first frequency, and the current drive circuit generates a periodic drive current under the control of the current control signal.

[0008] According to the monitoring device of at least one embodiment of the present disclosure, the current control signal is a square wave signal.

[0009] According to the monitoring device of at least one embodiment of the present disclosure, the current driving circuit includes: a switching unit, which periodically switches its conductive state under the control of the current control signal, and the conductive state of the switching unit causes the current driving circuit to generate a periodic driving current.

[0010] According to the monitoring device of at least one embodiment of the present disclosure, the modulation circuit is an oscillator, which can output a wave signal with a first frequency as the current control signal.

[0011] According to the monitoring device of at least one embodiment of the present disclosure, the current driving circuit further includes: a first operational amplifier and a first resistor; Wherein, the switch unit includes a first switch, a second switch, and a third switch; A first end of the first switch is connected to the positive input terminal of the first operational amplifier, and a second end of the first switch is connected to the negative electrode of the battery or battery pack; A first end of the second switch is connected to the output end of the first operational amplifier, and a second end of the second switch is connected to the negative electrode of the battery or battery pack; A first end of the third switch is connected to the positive electrode of the battery or battery pack, and a second end of the third switch is connected to the first end of the first resistor; The first end of the first resistor is also connected to the negative input terminal of the first operational amplifier, and the second end of the first resistor is connected to the negative electrode of the battery or battery pack; The output terminal of the first operational amplifier is further connected to the control terminal of the third switch to control the conduction degree of the third switch; The positive input terminal of the first operational amplifier is connected to a reference voltage.

[0012] According to the monitoring device of at least one embodiment of the present disclosure, the current control signal synchronously controls the first switch and the second switch via the control end of the first switch and the control end of the second switch, so that the first switch and the second switch are synchronously turned on or off.

[0013] According to the monitoring device of at least one embodiment of the present disclosure, the first switch, the second switch, and the third switch are all field effect transistor switches.

[0014] According to the monitoring device of at least one embodiment of the present disclosure, the voltage monitoring circuit includes: a first isolation capacitor, a second isolation capacitor, a fully differential operational amplifier, a first jumper resistor, and a second jumper resistor; The first end of the first isolation capacitor is used to connect to the positive electrode of the battery or battery pack, and the second end of the first isolation capacitor is connected to the negative input terminal of the fully differential operational amplifier; The first end of the second isolation capacitor is used to connect to the negative electrode of the battery or battery pack, and the second end of the second isolation capacitor is connected to the positive input terminal of the fully differential operational amplifier; Two ends of the first jumper resistor are respectively connected to the negative input terminal and the positive output terminal of the fully differential operational amplifier; Two ends of the second jumper resistor are respectively connected to the positive input terminal and the negative output terminal of the fully differential operational amplifier; The positive output terminal and the negative output terminal of the fully differential operational amplifier are used to output the AC response voltage after amplifying the AC response voltage.

[0015] According to the monitoring device of at least one embodiment of the present disclosure, the capacitance values ​​of the first isolation capacitor and the second isolation capacitor are equal, and the resistance values ​​of the first jumper resistor and the second jumper resistor are equal.

[0016] According to the monitoring device of at least one embodiment of the present disclosure, the voltage monitoring circuit also includes: an ADC circuit, which collects the amplified AC response voltage and converts it into a digital voltage signal. The signal output by the ADC circuit is a periodic digital voltage signal, and the periodic digital voltage signal is used to monitor the battery or battery pack.

[0017] According to at least one embodiment of the present disclosure, the monitoring device further includes: A demodulation circuit, wherein the demodulation frequency of the demodulation circuit is equal to the modulation frequency of the modulation circuit, and the demodulation circuit is used to demodulate the periodic digital voltage signal and output a demodulated voltage signal, wherein the demodulated voltage signal is an AC response component with the same frequency as the driving current.

[0018] According to at least one embodiment of the present disclosure, the monitoring device further includes: A low-pass filter performs low-pass filtering on the demodulated voltage signal to output a DC voltage signal or a low-frequency signal, wherein the DC voltage signal or the low-frequency signal is at least used to characterize the impedance of the battery or battery pack.

[0019] According to at least one embodiment of the present disclosure, the monitoring device further includes: The calculation and judgment module judges the signal output by the low-pass filter by executing a computer program to judge the internal resistance of the battery or battery pack, or judges the internal resistance of the battery or battery pack and judges the degree of aging of the battery or battery pack based on the internal resistance.

[0020] According to another aspect of the present disclosure, a battery system is provided, comprising: a battery or a battery pack; and a monitoring device according to any one embodiment of the present disclosure, wherein the monitoring device is configured to monitor the battery or the battery pack.

[0021] According to yet another aspect of the present disclosure, there is provided an electric device comprising the battery system according to any one of the embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0023] Figure 1 It is a schematic diagram of the overall structure of a monitoring device according to an embodiment of the present disclosure.

[0024] Figure 2 It is a schematic diagram of the overall structure of a monitoring device according to another embodiment of the present disclosure.

[0025] Figure 3 Schematic diagram of the circuit structure of a current driving circuit according to a preferred embodiment of the present invention.

[0026] Figure 4 It is a schematic structural diagram of a monitoring device according to another embodiment of the present disclosure.

[0027] Figure 5 It is a schematic structural diagram of a monitoring device according to another embodiment of the present disclosure.

[0028] Figure 6 It is a schematic structural diagram of a monitoring device according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] The present disclosure will be 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 intended to explain the relevant content and are not intended to limit the present disclosure. It should also be noted that, for ease of description, only the portions relevant to the present disclosure are shown in the accompanying drawings.

[0030] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present disclosure can be combined with each other. The technical solution of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0031] Unless otherwise stated, the exemplary embodiments / examples shown are to be understood as providing exemplary features of various details of some ways in which the technical concepts of the present disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of the various embodiments / examples may be further combined, separated, interchanged, and / or rearranged without departing from the technical concepts of the present disclosure.

[0032] The use of cross hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise indicated, the presence or absence of cross hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the order described. In addition, the same figure numbers represent the same components.

[0033] When a component is referred to as being “on,” “over,” “connected to,” or “coupled to” another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another component, there are no intervening components present. For this purpose, the term “connected” may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0034] For descriptive purposes, the present disclosure may use spatially relative terms such as "below," "beneath," "under," "down," "above," "upper," "above," "higher," and "side (e.g., in a "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the drawings is turned over, a component described as "below" or "beneath" another component or feature would then be positioned "above" the other component or feature. Thus, the exemplary term "below" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and as such, the spatially relative descriptors used herein should be interpreted accordingly.

[0035] The terms used herein are for the purpose of describing specific embodiments and are not intended to be restrictive. As used herein, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, the features, integral bodies, steps, operations, parts, assemblies and / or their groups stated are explained, but the presence or addition of one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups is not excluded. It should also be noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values ​​and / or the values ​​provided that will be recognized by those of ordinary skill in the art.

[0036] Figure 1 It is a schematic block diagram of the overall structure of a monitoring device according to an embodiment of the present disclosure.

[0037] refer to Figure 1 In some embodiments of the present disclosure, the monitoring device 1000 of the present disclosure is used to monitor a battery or battery pack 2000. The monitoring device 1000 includes: A voltage monitoring circuit 100, the voltage monitoring circuit 100 is used to be connected between the positive electrode and the negative electrode of the battery or battery pack; The current driving circuit 200 is used to be connected between the positive electrode and the negative electrode of the battery or battery pack, and the current driving circuit 200 can generate a driving current (with an intensity of I T ), the driving current can flow into the negative electrode of the battery or battery pack and flow out of the positive electrode of the battery or battery pack; The voltage monitoring circuit 100 is at least configured to monitor an AC response voltage (Vin, ac) between the positive electrode and the negative electrode caused by the driving current when the current driving circuit 200 generates the driving current.

[0038] The monitoring device 1000 of the present disclosure implements non-invasive online monitoring of the battery status by applying a controllable driving current across the battery or battery pack and simultaneously monitoring the AC response voltage generated. Specifically, the current driving circuit 200 is connected between the positive and negative electrodes of the battery and can generate a current with an intensity of I T The driving current flows from the negative electrode of the battery or battery pack and out of the positive electrode, that is, the current is injected into the battery from the outside. This current direction design allows the monitoring device 1000 to superimpose a small test excitation signal without affecting the normal charging and discharging of the battery, thereby avoiding interference with the system.

[0039] The voltage monitoring circuit 100 is also connected between the positive and negative electrodes of the battery, and is used to monitor the AC response voltage (Vin, ac) generated by the driving current at both ends of the battery or battery pack in real time during the process of the current driving circuit 200 generating the driving current.

[0040] The monitoring device 1000 disclosed herein simultaneously acquires excitation (driving current) and response (AC voltage) within the same time window, forming a complete "excitation-response" measurement loop. This provides a reliable data foundation for subsequent analysis of the battery's AC impedance, internal resistance changes, and state of health (SOH). Compared to conventional methods that rely on voltage and current integration, the monitoring device 1000 disclosed herein can more sensitively reflect the electrochemical aging process within the battery, with higher measurement accuracy and interference resistance.

[0041] Continue to refer Figure 1 In some embodiments of the present disclosure, the monitoring device 1000 of the present disclosure further includes: The modulation circuit 300 is used to generate a current control signal. The modulation frequency of the modulation circuit is a first frequency, thereby generating a current control signal with a first frequency. The current driving circuit 200 generates a periodic driving current (with an intensity of I T ).

[0042] The modulation circuit 300 is used to generate a current control signal with a fixed frequency. The frequency of the signal is a first frequency, which serves as a modulation reference for the drive current. Under the action of the current control signal, the drive current (I T ) presents periodic changes, such as being periodically applied to both ends of the battery or battery pack in the form of a square wave, pulse or sine wave.

[0043] By introducing periodic excitation, the present invention modulates the battery's response to the drive current into a specific frequency range, separating it from the battery system's DC bias, low-frequency operating noise (such as charge and discharge current fluctuations), and high-frequency electromagnetic interference in the frequency domain. This frequency-selective design significantly improves the recognizability of the AC response signal and the measurement signal-to-noise ratio.

[0044] At the same time, the periodic drive current provides a clear time and frequency reference for subsequent signal processing, facilitating the voltage monitoring circuit's synchronous sampling, filtering, or demodulation of the AC response voltage, thereby more accurately extracting the AC component associated with the excitation signal. This is particularly suitable for monitoring batteries under dynamic operating conditions, enabling high-precision, interference-resistant detection of battery status without affecting normal operation.

[0045] The modulation circuit may be an oscillator, which can output a wave signal with a first frequency (ω) as the current control signal.

[0046] The oscillator may be one of an RC oscillator, an LC oscillator, a crystal oscillator, or a voltage controlled oscillator (VCO).

[0047] The oscillator outputs a wave signal that can be a square wave, a sine wave, a triangle wave, or a pulse signal, with a frequency corresponding to the first frequency (ω). This wave signal serves as a current control signal, and is used directly or through a drive circuit to control the operating state of the current drive circuit 200, causing it to generate a periodic drive current synchronized with the control signal.

[0048] Preferably, the current driving signal disclosed herein is a square wave signal.

[0049] Figure 2 It is a schematic block diagram of the overall structure of a monitoring device according to another embodiment of the present disclosure.

[0050] refer to Figure 2 ,exist Figure 1 On the basis of the above, the current driving circuit 200 of the monitoring device 1000 of this embodiment includes: The switch unit 201 periodically switches its conduction state under the control of the current control signal. The conduction state of the switch unit 201 enables the current driving circuit 200 to generate a periodic driving current (with an intensity of I T ).

[0051] The switch unit 201 is a key control unit in the current driving circuit 200. It periodically switches its conduction state under the drive of the current control signal provided by the modulation circuit 300. The change of the conduction state is used to control the driving current (I T) is generated, so that the current driving circuit 200 outputs a periodic driving current synchronized with the current control signal.

[0052] Through the periodic operation of switch unit 201, the driving current alternates between "on" and "off" at a first frequency, forming an excitation signal with a square wave, pulse, or other periodic waveform. This periodic on-off mechanism gives the AC response signal generated by the battery clear time and frequency characteristics, facilitating the subsequent separation of valid signals from complex operating conditions.

[0053] The switch section 201 disclosed herein may be composed of one or more electronic switches, whose switching behavior is precisely synchronized with the current control signal, ensuring the timing consistency of each excitation, improving the controllability of the driving current, and providing a reliable synchronization reference for the voltage monitoring circuit 100, which is beneficial to improving the repeatability and stability of the overall measurement.

[0054] Figure 3 2 is a schematic diagram of the circuit structure of a current driving circuit 200 according to a preferred embodiment of the present disclosure.

[0055] refer to Figure 3 For the monitoring device 1000 of each of the above embodiments, the current driving circuit 200 of the present disclosure further includes: a first operational amplifier 202 and a first resistor 203 (R0).

[0056] The switch unit 201 includes a first switch S1 , a second switch S2 , and a third switch S3 .

[0057] A first end of the first switch S1 is connected to the positive input end of the first operational amplifier 202 , and a second end of the first switch S1 is connected to the negative electrode bat- of the battery or battery pack.

[0058] A first end of the second switch S2 is connected to the output end of the first operational amplifier 202 , and a second end of the second switch S2 is connected to the negative electrode bat- of the battery or battery pack.

[0059] A first end of the third switch S3 is connected to the positive electrode bat+ of the battery or battery pack, and a second end of the third switch S3 is connected to the first end of the first resistor 203 .

[0060] The first end of the first resistor 203 is also connected to the negative input terminal of the first operational amplifier 202, and the second end of the first resistor 203 is connected to the negative electrode bat- of the battery or battery pack.

[0061] The output terminal of the first operational amplifier 202 is further connected to the control terminal of the third switch S3 to control the conduction degree of the third switch S3 (to make it operate in the linear region, thereby controlling the current flowing through the first resistor R0).

[0062] The positive input terminal of the first operational amplifier 202 is connected to a reference voltage (Vref).

[0063] Preferably, the current control signal synchronously controls the first switch S1 and the second switch S2 via the control end of the first switch S1 and the control end of the second switch S2, so that the first switch S1 and the second switch S2 are synchronously turned on or off.

[0064] The following text Figure 3 The operation process of the circuit shown is explained.

[0065] The positive input terminal of the first operational amplifier 202 is connected to the negative electrode bat- of the battery or battery pack (usually used as a reference ground, with a voltage of 0V) through the first switch S1; the positive input terminal of the first operational amplifier is also connected to a reference voltage Vref (applied through an independent reference voltage source, such as a reference voltage chip); when the first switch S1 is turned on, the positive input terminal is short-connected to the negative electrode bat- of the battery; when S1 is disconnected, the reference voltage Vref acts on the positive input terminal.

[0066] The negative input terminal of the first operational amplifier 202 is connected between the first resistor 203 (R0) and the third switch S3 to detect the voltage (I T ·R0).

[0067] One end of the third switch S3 (such as a MOSFET) is connected to the battery positive terminal bat+, and the other end is connected to the first end of R0. The second end of R0 is connected to the battery negative terminal bat-, forming a current path: bat+ → S3 → R0 → bat-.

[0068] The output terminal of the first operational amplifier 202 is connected to the control terminal of the third switch S3 to control the conduction degree of the third switch S3.

[0069] The second switch S2 is connected in series between the output terminal of the first operational amplifier 202 and the negative electrode bat- of the battery or battery pack.

[0070] Negative feedback control: The first switch S1 and the second switch S2 are synchronously controlled by the same current control signal, and are used to periodically connect or disconnect the reference voltage Vref to the positive input terminal of the operational amplifier, and the output terminal of the operational amplifier to the negative terminal of the battery bat-.

[0071] The positive input terminal of the first operational amplifier is also connected to a reference voltage source Vref; when the first switch S1 is turned on, the positive input terminal is short-connected to the negative electrode bat- of the battery; when S1 is disconnected, the reference voltage Vref acts on the positive input terminal.

[0072] When S1 and S2 are disconnected, Vref is connected, and the first operational amplifier 202 adjusts the conduction degree of the third switch S3 to stabilize the current flowing through the first resistor R0 to I T = Vref / R0.

[0073] When S1 and S2 are turned on, Vref is blocked, the output of the operational amplifier is pulled low, S3 is turned off, and the drive current is zero.

[0074] Function implementation: Drive current I T The periodic on-off of is controlled by the switching action of S1 and S2, and the frequency is consistent with the output signal of the modulation circuit 300 (ω).

[0075] The first operational amplifier 202 adjusts the conduction state of S3 to ensure that I T The amplitude is stable, and the direction is flowing in from the negative electrode and out from the positive electrode.

[0076] This design is suitable for battery impedance testing or health status monitoring. The voltage monitoring circuit 100 can synchronously measure the driving current I T The AC response voltage of the battery under action is used to analyze the battery internal resistance or battery status, etc.

[0077] For the switch unit 201 described in the present disclosure, preferably, the first switch S1 , the second switch S2 and the third switch S3 are all field effect transistor switches.

[0078] In light of the technical solution disclosed herein, those skilled in the art may select or change the number and type of the switch parts 201 , which all fall within the protection scope of the present disclosure.

[0079] Figure 4 It is a schematic block diagram of the structure of a monitoring device according to another embodiment of the present disclosure.

[0080] refer to Figure 4 Preferably, the voltage monitoring circuit 100 disclosed herein includes: a first isolation capacitor C1, a second isolation capacitor C2, a fully differential operational amplifier 110, a first jumper resistor R1, and a second jumper resistor R2.

[0081] The first end of the first isolation capacitor C1 is used to connect to the positive electrode of the battery or battery pack, and the second end of the first isolation capacitor C1 is connected to the negative input terminal of the fully differential operational amplifier 110 .

[0082] A first end of the second isolation capacitor C2 is used to connect to the negative electrode of the battery or battery pack, and a second end of the second isolation capacitor C2 is connected to the positive input terminal of the fully differential operational amplifier 110 .

[0083] Two ends of the first jumper resistor R1 are respectively connected to the negative input terminal and the positive output terminal of the fully differential operational amplifier 110 .

[0084] Two ends of the second jumper resistor R2 are respectively connected to the positive input terminal and the negative output terminal of the fully differential operational amplifier 110 .

[0085] The positive output terminal and the negative output terminal of the fully differential operational amplifier 110 are used to output an AC response voltage (Vout) obtained by amplifying the AC response voltage (Vin, ac).

[0086] Preferably, the capacitance values ​​of the first isolation capacitor and the second isolation capacitor are equal, and the resistance values ​​of the first jumper resistor and the second jumper resistor are equal.

[0087] The following text Figure 4 The operation process of the voltage monitoring circuit 100 is described below.

[0088] The voltage monitoring circuit 100 is used to accurately extract the AC response voltage (Vin, ac) generated by a battery or battery pack under the influence of a periodic drive current and amplify it for subsequent analog-to-digital conversion and analysis. Because the battery itself has a relatively high DC voltage, the AC response signal to be measured is very weak compared to this DC voltage. Direct input to the amplifier can easily lead to saturation or distortion. Therefore, it is necessary to effectively isolate the DC component and allow only the AC signal to pass.

[0089] To this end, the present disclosure provides a first isolation capacitor C1 and a second isolation capacitor C2, connected in series between the battery's positive terminal and the negative input terminal, and between the battery's negative terminal and the positive input terminal, respectively, to form an AC coupling structure. This design blocks the battery's DC voltage from transmitting to the amplifier's input terminal, allowing only the AC response voltage signal caused by the drive current to pass through, forming an RC high-pass filter characteristic, effectively protecting subsequent circuits and achieving DC isolation.

[0090] Fully differential operational amplifier 110, along with first and second jumper resistors R1 and R2, forms a negative feedback amplifier circuit. R1 connects the negative input terminal to the positive output terminal, while R2 connects the positive input terminal to the negative output terminal, forming a symmetrical differential feedback path. This structure linearly amplifies the input differential AC signal and outputs a pair of amplified AC response voltages (Vout+ and Vout−) with equal amplitude and opposite phase. The difference between these voltages is the effective output signal, Vout = Vout+ − Vout−.

[0091] The fully differential architecture effectively suppresses common-mode noise (such as electromagnetic interference and power supply fluctuations), significantly improving the signal-to-noise ratio and interference immunity. Furthermore, the differential output facilitates direct interface with differential ADC circuits, reducing signal loss and increasing dynamic range. Furthermore, the symmetrical circuit design helps offset errors caused by device parameter mismatch, further enhancing measurement stability.

[0092] Preferably, the capacitance values ​​of the first isolation capacitors C1 and C2 are equal, and the resistance values ​​of the first jumper resistors R1 and R2 are equal. This symmetrical design ensures the matching of the differential channels, helps improve the common mode rejection ratio (CMRR), and ensures the linearity and consistency of the signal amplification process.

[0093] In summary, voltage monitoring circuit 100 achieves DC isolation and AC coupling through C1 and C2. Combined with a fully differential operational amplifier 110 and the negative feedback network formed by R1 and R2, it can amplify weak AC response signals with high precision and low noise, outputting a stable differential voltage Vout. This provides reliable data for subsequent analysis of the battery's internal resistance, state of health (SOH), or state of charge (SOC). This circuit is particularly suitable for online battery impedance measurement under high-noise and dynamic conditions.

[0094] Figure 5 It is a schematic structural diagram of a monitoring device according to another embodiment of the present disclosure.

[0095] refer to Figure 5 Preferably, the voltage monitoring circuit 100 of the present disclosure further includes: The ADC circuit 120 collects the amplified AC response voltage (Vout) and converts it into a digital voltage signal (the digital voltage signal is also periodic). The signal output by the ADC circuit 120 is a periodic digital voltage signal, and the periodic digital voltage signal is used to monitor the battery or battery pack.

[0096] The ADC circuit 120 is used to convert the analog AC response voltage signal (Vout) output by the voltage monitoring circuit 100 into a digital form to facilitate subsequent digital signal processing and analysis.

[0097] Specifically, the ADC circuit 120 receives the differential voltage signals (Vout+ and Vout−) from the positive and negative output terminals of the fully differential operational amplifier 110 , and performs synchronous sampling and analog-to-digital conversion on the differential voltage signals to generate a digital voltage signal corresponding to the input signal (i.e., the AC response voltage signal).

[0098] Because the drive current is a periodic signal (frequency ω), the AC response voltage (Vin,ac) generated by the battery and the amplified Vout also exhibit the same periodic characteristics. Therefore, the digital voltage signal output by the ADC circuit 120 is also periodic, with a frequency consistent with the drive current.

[0099] Preferably, the ADC circuit 120 adopts a differential input mode, which matches the output form of the fully differential operational amplifier 110, and can further improve the signal-to-noise ratio and measurement accuracy.

[0100] The periodic digital voltage signal can be used directly for preliminary analysis of the battery's status or as input to subsequent signal processing modules (such as demodulation circuits) to accurately measure key parameters such as the battery's AC impedance and internal resistance changes. This design enables the monitoring device to operate stably under complex operating conditions, providing reliable data support for battery state of health (SOH) assessment.

[0101] Continue to refer Figure 5 In a preferred embodiment of the present disclosure, the monitoring device 1000 further includes: The demodulation circuit 400 has a demodulation frequency that is equal to the modulation frequency of the modulation circuit 300. The demodulation circuit 400 is used to demodulate the periodic digital voltage signal and output a demodulated voltage signal, which is an AC response component with the same frequency as the driving current.

[0102] The demodulation circuit 400 is used to extract the AC response component with the same frequency as the drive current from the periodic digital voltage signal output by the ADC circuit 120, thereby achieving high-precision detection of weak signals. Specifically, the demodulation circuit 400 can employ synchronous demodulation technology, with its demodulation frequency strictly consistent with the frequency of the current control signal generated by the modulation circuit 300 (i.e., the first frequency ω).

[0103] Synchronous demodulation works by multiplying a periodic digital voltage signal with a reference signal that has the same frequency and phase as the original excitation signal. Because the battery's AC response signal has a defined phase relationship with the drive current, while ambient noise is typically random, synchronous demodulation can separate the target signal from the noise.

[0104] In the present disclosure, demodulation circuit 400 receives a periodic digital voltage signal from ADC circuit 120 and performs demodulation processing using a reference signal synchronized with modulation circuit 300. The demodulated output voltage signal primarily consists of two components: an AC response component with the same frequency as the drive current, i.e., the desired effective signal; and a high-frequency component with a frequency of 2ω. Subsequent low-pass filtering removes the high-frequency component, retaining the effective DC or low-frequency signal. The amplitude of this signal is proportional to the battery's AC impedance at frequency ω.

[0105] Preferably, the demodulation circuit 400 can be implemented digitally and can be integrated into a microcontroller or a digital signal processor, and can be easily integrated with an existing BMS system.

[0106] The demodulation circuit 400 may adopt an existing demodulation circuit structure, all of which fall within the protection scope of the present disclosure.

[0107] Continue to refer Figure 5 Preferably, the monitoring device 1000 of the present disclosure further includes: A low-pass filter 500 performs low-pass filtering on the demodulated voltage signal and outputs a DC voltage signal or a low-frequency signal, wherein the DC voltage signal or the low-frequency signal is at least used to characterize the impedance of the battery or battery pack.

[0108] The low-pass filter 500 is used to filter the demodulated voltage signal output by the demodulation circuit 400, removing high-frequency components and extracting a valid signal that characterizes the battery impedance. Specifically, the cutoff frequency of the low-pass filter 500 can be set to a frequency lower than the double frequency component (2ω) generated during the demodulation process but higher than the system noise frequency. This effectively filters out high-frequency interference while retaining the DC or low-frequency signal directly related to the battery impedance.

[0109] During synchronous demodulation, due to the multiplication characteristics, the demodulated signal contains two main components: an AC response component (i.e., the effective signal) with the same frequency as the drive current, and a high-frequency component with a frequency of 2ω. The amplitude of the effective signal is proportional to the battery's AC impedance at the excitation frequency ω. The high-frequency component, however, is a byproduct of the demodulation process and does not contribute to the impedance measurement and may introduce errors. Low-pass filtering can remove the high-frequency component, retaining only the DC or low-frequency components directly related to the impedance information.

[0110] The amplitude of the DC voltage signal or low-frequency signal output by low-pass filter 500 directly reflects the battery's AC impedance at frequency ω. When the excitation current IT remains constant, the amplitude of this signal is proportional to the battery impedance and can be used to assess the battery's state of health (SOH). For example, as a battery ages, its internal resistance typically increases, causing the amplitude of this signal to increase accordingly.

[0111] The cutoff frequency of low-pass filter 500 is preferably optimized based on the actual application scenario. In battery impedance measurement, it is typically set between ω / 10 and ω / 100, effectively filtering out the 2ω component without excessively attenuating the valid signal. This filter can be an analog RC low-pass filter or a digital FIR or IIR filter, with flexibility depending on system requirements.

[0112] Through processing by low-pass filter 500, the monitoring device 1000 of the present disclosure can output a stable and reliable signal that directly represents the battery's impedance characteristics, providing critical data support for battery health assessment, fault diagnosis, and lifespan prediction. This "modulation-demodulation-low-pass filtering" signal processing chain is particularly suitable for battery monitoring in high-noise environments, enabling high-precision detection of subtle impedance changes.

[0113] For example, Vout can be expressed as: Vout = Vin·jω·C·R; Vin = Vbat+ - Vbat-; Vin = Vin,dc + Vin,ac; Vin,dc is the DC voltage of the battery, and Vin,ac is the AC response voltage.

[0114] C is the capacitance of the isolation capacitor C1 or C2, and R is the resistance of the transimpedance amplifier R1 or R2, that is, C1=C2=C, R1=R2=R.

[0115] ∣Vout∣=∣Vin∣·∣jω·C·R∣;∣j∣=1; ∣Vout∣=∣Vin∣·∣ω·C·R∣.

[0116] Therefore, when ω<<1 / RC, |Vout|=0, that is, the DC signal is attenuated (isolated).

[0117] When ω>>1 / RC, the AC signal is amplified.

[0118] We can let ω = 10·(1 / RC).

[0119] Then Vout = (Vref / R0)·(N·Rint)·cosωt·∣jω·RC∣; Where N is the number of batteries connected in series.

[0120] For Vout = (Vref / R0)·(N·Rint)·cosωt·|jω·RC|, it can be demodulated using the demodulation circuit 400 of the present disclosure and converted into a Fourier expression: Vout = (Vref / R0)·(N·Rint)·cosωt·∣ω·RC∣·A1 + (Vref / R0)·(N·Rint)·cos3ωt·∣3ω·RC∣·A3 +(Vref / R0)·(N·Rint)·cos5ωt·∣5ω·RC∣·A5 +…….

[0121] Where, “(Vref / R0)·(N·Rint)·cos3ωt·|3ω·RC|·A3 +(Vref / R0)·(N·Rint)·cos5ωt·∣5ω·RC∣·A5 +..." can be filtered out by the low-pass filter 500, and the cutoff frequency point of the low-pass filter can be set to ω / 10.

[0122] Among them, A1, A3, A5, etc. are Fourier expansion coefficients.

[0123] Since the driving current of the present disclosure is a periodic signal, and preferably a square wave signal, the Fourier series of the square wave only contains cosine terms of odd harmonics.

[0124] For periodic signals (such as square waves), the Fourier coefficients are known. For example, for a square wave with an amplitude of 1 and a period of T, its Fourier coefficients are: An = 4 / (πn), n=1,3,5…….

[0125] Then Vout = (Vref / R0)·(N·Rint)·cosωt·|ω·RC|·A1, where (Vref / R0)·cosωt·|ω·RC|·A1 constitutes a known constant coefficient.

[0126] It can be seen that the digital signal of Vout is proportional to (N·Rint).

[0127] Figure 6 It is a schematic structural diagram of a monitoring device according to another embodiment of the present disclosure.

[0128] refer to Figure 6 , the monitoring device 1000 further includes: The calculation and judgment module 600 judges the signal output by the low-pass filter 500 by executing a computer program to judge the internal resistance of the battery or battery pack, or further judges the degree of aging of the battery or battery pack based on the internal resistance.

[0129] The calculation and judgment module 600 can be in the form of a chip or a calculation and judgment module on a chip. This disclosure does not specifically limit this and all fall within the scope of protection of this disclosure.

[0130] In practical applications, the calculation and judgment module 600 can implement one or more of the following functions: Real-time monitoring and recording of battery impedance change trends; When the impedance exceeds the preset threshold, the warning or protection mechanism is triggered; Combined with parameters such as temperature and charge and discharge history, it provides a more accurate health status assessment; Generates battery status reports for system diagnostics or user notifications.

[0131] Preferably, the calculation and judgment module 600 is implemented digitally and can be integrated into the main control chip of the battery management system (BMS) or exist as a standalone signal processing unit. This module can take the form of an application-specific integrated circuit (ASIC), a microcontroller (MCU), a digital signal processor (DSP), or a field-programmable gate array (FPGA), depending on the actual application scenario. Regardless of the implementation method, its core function is to convert physical measurement signals into meaningful battery status information, providing a decision-making basis for safe battery use and lifespan management.

[0132] The present disclosure further provides a battery system, comprising: a battery or a battery pack; and a monitoring device 1000 according to any one embodiment of the present disclosure, wherein the monitoring device 1000 is configured to monitor the battery or the battery pack.

[0133] The present disclosure also provides an electrical device, comprising the battery system according to any one of the embodiments of the present disclosure.

[0134] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present disclosure. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0135] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0136] Those skilled in the art will appreciate that the above embodiments are merely intended to clearly illustrate the present disclosure and are not intended to limit the scope of the present disclosure. Other changes or modifications may be made based on the above disclosure, and such changes or modifications are still within the scope of the present disclosure.

Claims

1. A monitoring device for monitoring a battery or battery pack, characterized in that: include: a voltage monitoring circuit, the voltage monitoring circuit being connected between the positive electrode and the negative electrode of the battery or battery pack; as well as a current driving circuit, the current driving circuit being configured to be connected between the positive electrode and the negative electrode of the battery or battery pack, the current driving circuit being capable of generating a driving current that can flow from the negative electrode of the battery or battery pack and flow out from the positive electrode of the battery or battery pack; The voltage monitoring circuit is at least used for monitoring an AC response voltage between the positive electrode and the negative electrode caused by the driving current when the current driving circuit generates the driving current.

2. The monitoring device according to claim 1, characterized in that The monitoring device further comprises: a modulation circuit, the modulation circuit being configured to generate a current control signal, the modulation frequency of the modulation circuit being a first frequency, thereby generating a current control signal having the first frequency, and the current drive circuit generating a periodic drive current under the control of the current control signal; Preferably, the current control signal is a square wave signal.

3. The monitoring device according to claim 2, characterized in that The current driving circuit includes: A switch unit is provided, wherein the switch unit periodically switches its conduction state under the control of the current control signal, and the conduction state of the switch unit enables the current driving circuit to generate a periodic driving current.

4. The monitoring device according to claim 2 or 3, characterized in that: The modulation circuit is an oscillator, which can output a wave signal with a first frequency as the current control signal.

5. The monitoring device according to claim 3, characterized in that The current driving circuit further includes: a first operational amplifier and a first resistor; Wherein, the switch unit includes a first switch, a second switch, and a third switch; A first end of the first switch is connected to the positive input terminal of the first operational amplifier, and a second end of the first switch is connected to the negative electrode of the battery or battery pack; A first end of the second switch is connected to the output end of the first operational amplifier, and a second end of the second switch is connected to the negative electrode of the battery or battery pack; A first end of the third switch is connected to the positive electrode of the battery or battery pack, and a second end of the third switch is connected to the first end of the first resistor; The first end of the first resistor is also connected to the negative input terminal of the first operational amplifier, and the second end of the first resistor is connected to the negative electrode of the battery or battery pack; The output terminal of the first operational amplifier is further connected to the control terminal of the third switch to control the conduction degree of the third switch; The positive input terminal of the first operational amplifier is connected to a reference voltage.

6. The monitoring device according to claim 5, characterized in that The current control signal synchronously controls the first switch and the second switch via the control end of the first switch and the control end of the second switch, so that the first switch and the second switch are synchronously turned on or off.

7. The monitoring device according to claim 5, characterized in that The first switch, the second switch and the third switch are all field effect transistor switches.

8. The monitoring device according to any one of claims 1 to 7, characterized in that: The voltage monitoring circuit includes: a first isolation capacitor, a second isolation capacitor, a fully differential operational amplifier, a first jumper resistor and a second jumper resistor; The first end of the first isolation capacitor is used to connect to the positive electrode of the battery or battery pack, and the second end of the first isolation capacitor is connected to the negative input terminal of the fully differential operational amplifier; The first end of the second isolation capacitor is used to connect to the negative electrode of the battery or battery pack, and the second end of the second isolation capacitor is connected to the positive input terminal of the fully differential operational amplifier; Two ends of the first jumper resistor are respectively connected to the negative input terminal and the positive output terminal of the fully differential operational amplifier; Two ends of the second jumper resistor are respectively connected to the positive input terminal and the negative output terminal of the fully differential operational amplifier; The positive output terminal and the negative output terminal of the fully differential operational amplifier are used to output the AC response voltage after amplifying the AC response voltage; Optionally, the capacitance values ​​of the first isolation capacitor and the second isolation capacitor are equal, and the resistance values ​​of the first jumper resistor and the second jumper resistor are equal; Optionally, the voltage monitoring circuit further includes: an ADC circuit, wherein the ADC circuit collects the amplified AC response voltage and converts it into a digital voltage signal, wherein the signal output by the ADC circuit is a periodic digital voltage signal, and the periodic digital voltage signal is used to monitor the battery or battery pack; Optionally, the monitoring device further includes: a demodulation circuit, wherein the demodulation frequency of the demodulation circuit is equal to the modulation frequency of the modulation circuit, the demodulation circuit is used to demodulate the periodic digital voltage signal and output a demodulated voltage signal, wherein the demodulated voltage signal is an AC response component having the same frequency as the drive current; Optionally, the monitoring device further includes: a low-pass filter, which performs low-pass filtering on the demodulated voltage signal and outputs a DC voltage signal or a low-frequency signal, wherein the DC voltage signal or the low-frequency signal is used to at least characterize the impedance of the battery or battery pack; Optionally, the monitoring device further includes: The calculation and judgment module judges the signal output by the low-pass filter by executing a computer program to judge the internal resistance of the battery or battery pack, or judges the internal resistance of the battery or battery pack and judges the degree of aging of the battery or battery pack based on the internal resistance.

9. A battery system, characterized in that: include: Batteries or battery packs; as well as The monitoring device according to any one of claims 1 to 8, wherein the monitoring device is used to monitor the battery or battery pack.

10. An electrical device, characterized in that: A battery system comprising the battery system of claim 9.

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