Monitoring devices, battery systems and electrical equipment

Abstract

This disclosure provides a monitoring device, a battery system, and an electrical appliance. The monitoring device, used for monitoring a battery or battery pack, includes: a voltage monitoring circuit connected between the positive and negative terminals of the battery or battery pack; a current driving circuit connected between the positive and negative terminals of the battery or battery pack, capable of generating a driving current that flows into the negative terminal of the battery or battery pack and flows out from the positive terminal; the voltage monitoring circuit is at least used to monitor the AC response voltage between the positive and negative terminals caused by the driving current when the current driving circuit generates the driving current.

Description

Technical Field

[0001] This disclosure relates to the field of battery-related technologies, and in particular to a monitoring device, a battery system, and an electrical appliance. Background Technology

[0002] As the core energy unit in electric vehicles, energy storage systems, portable electronic devices, and other products, the performance degradation and aging of batteries directly affect the safety, range, and lifespan of the system. Therefore, real-time monitoring of battery status, especially the 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 mainly include voltage detection, current integration, temperature monitoring, and model-based estimation algorithms. These methods can reflect the battery's state of charge (SOC) and usage to a certain extent, but they have significant limitations in assessing the degree of internal aging of the battery. For example, irreversible changes may occur in batteries during cycle use, such as electrode material degradation, electrolyte decomposition, and increased internal resistance. These changes often manifest as slow, non-linear shifts in voltage and current signals, making them difficult to identify directly 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. This results in measurement results being heavily influenced by the battery's DC bias voltage, leading to a low signal-to-noise ratio and making it difficult to achieve stable and reliable battery monitoring.

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

[0006] According to one aspect of this disclosure, a monitoring device is provided for monitoring a battery or battery pack, comprising: A voltage monitoring circuit is provided for connection between the positive and negative terminals of the battery or battery pack. A current driving circuit is used to connect between the positive and negative terminals of the battery or battery pack. The current driving circuit is capable of generating a driving current that can flow into the negative terminal of the battery or battery pack and flow out from the positive terminal of the battery or battery pack. The voltage monitoring circuit is at least used to monitor the AC response voltage between the positive and negative terminals caused by the driving current when the current driving circuit generates the driving current.

[0007] According to at least one embodiment of the monitoring device of this disclosure, the monitoring device further includes: A 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. The current driving circuit generates a periodic driving current under the control of the current control signal.

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

[0009] According to at least one embodiment of the monitoring device of the present disclosure, the current driving circuit includes: a switching part, the switching part periodically switching its conduction state under the control of the current control signal, the conduction state of the switching part causing the current driving circuit to generate a periodic driving current.

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

[0011] According to at least one embodiment of the monitoring device of this disclosure, the current driving circuit further includes: a first operational amplifier and a first resistor; The switching unit includes a first switch, a second switch, and a third switch; The first terminal of the first switch is connected to the positive input terminal of the first operational amplifier, and the second terminal of the first switch is connected to the negative terminal of the battery or battery pack. The first terminal of the second switch is connected to the output terminal of the first operational amplifier, and the second terminal of the second switch is connected to the negative terminal of the battery or battery pack. The first terminal of the third switch is connected to the positive terminal of the battery or battery pack, and the second terminal of the third switch is connected to the first terminal 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 terminal of the battery or battery pack. The output terminal of the first operational amplifier is also 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 at least one embodiment of the monitoring device of this disclosure, the current control signal synchronously controls the first switch and the second switch via the control terminal of the first switch and the control terminal of the second switch, so that the first switch and the second switch are synchronously turned on or off.

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

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

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

[0016] According to at least one embodiment of the monitoring device of this disclosure, the voltage monitoring circuit further includes: an ADC circuit, which acquires 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.

[0017] According to at least one embodiment of the monitoring device of this disclosure, the monitoring device further includes: The demodulation circuit has a demodulation frequency 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, which is an AC response component with the same frequency as the driving current.

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

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

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

[0021] According to another aspect of this disclosure, an electrical device is provided, including a battery system according to any embodiment of this disclosure. Attached Figure Description

[0022] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, 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 This is a schematic diagram of the overall structure of a monitoring device according to one embodiment of the present disclosure.

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

[0025] Figure 3 This is a schematic diagram of the circuit structure of a current driving circuit according to a preferred embodiment of the present disclosure.

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

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

[0028] Figure 6 This is a schematic diagram of the monitoring device according to another embodiment of the present disclosure. Detailed Implementation

[0029] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the accompanying drawings.

[0030] It should be noted that, where there is no conflict, the embodiments and features described in this disclosure can be combined with each other. The technical solutions of this disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

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

[0032] The use of crosshairs and / or shading in the accompanying drawings is generally used to clarify the boundaries between adjacent components. Thus, unless otherwise stated, the presence or absence of crosshairs or shading does not convey or indicate any preference or requirement for the specific material, material properties, dimensions, proportions, commonalities between the illustrated components, or any other characteristics, properties, etc., of the components. Furthermore, in the accompanying drawings, the dimensions and relative dimensions of components may be exaggerated for clarity and / or descriptive purposes. When exemplary embodiments can be implemented differently, a specific process sequence may be performed in a different order than that described. For example, two consecutively described processes may be performed substantially simultaneously or in the reverse order of their description. Furthermore, the same reference numerals denote the same components.

[0033] When a component is referred to as being "on" or "above" another component, "connected to," or "joined to" another component, the component may be directly on, directly connected to, or directly joined to the other component, or there may be intermediate components. However, when a component is referred to as being "directly on" another component, "directly connected to," or "directly joined to" another component, there are no intermediate components. Therefore, the term "connection" can refer to a physical connection, an electrical connection, etc., and may or may not have intermediate components.

[0034] For descriptive purposes, this disclosure may use spatial relative terms such as “below,” “under,” “below,” “down,” “above,” “above,” “higher,” and “side (e.g., in a “sidewall”)” to describe the relationship between one component and another component as shown in the accompanying drawings. In addition to the orientations depicted in the drawings, the spatial relative terms are also intended to encompass different orientations of the device during use, operation, and / or manufacture. For example, if the device in the drawings is flipped, a component described as “below” or “under” another component or feature would subsequently be positioned “above” said other component or feature. Thus, the exemplary term “below” can encompass both “above” and “below” orientations. Furthermore, the device may be otherwise positioned (e.g., rotated 90 degrees or in other orientations), thus interpreting the spatial relative descriptive terms used herein accordingly.

[0035] The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. Furthermore, when the terms “comprising” and / or “including” and variations thereof are used in this specification, it indicates the presence of the stated features, integrals, steps, operations, parts, components, and / or groups thereof, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, parts, components, and / or groups thereof. It should also be noted that, as used herein, the terms “substantially,” “about,” and other similar terms are used as approximate terms rather than as terms of degree, thus explaining the inherent biases in measurements, calculated values, and / or provided values ​​that would be recognized by one of ordinary skill in the art.

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

[0037] refer to Figure 1 In some embodiments of this disclosure, the monitoring device 1000 is used to monitor a battery or battery pack 2000. The monitoring device 1000 includes: A voltage monitoring circuit 100 is used to connect between the positive and negative terminals of the battery or battery pack. A current driving circuit 200 is connected between the positive and negative terminals of the battery or battery pack, and the current driving circuit 200 is capable of generating a driving current (intensity I). T The driving current can flow in from the negative terminal of the battery or battery pack and flow out from the positive terminal of the battery or battery pack; The voltage monitoring circuit 100 is at least used to monitor the AC response voltage (Vin,ac) between the positive and negative terminals caused by the driving current when the current driving circuit 200 generates the driving current.

[0038] The monitoring device 1000 disclosed herein achieves non-invasive online monitoring of the battery status by applying a controllable drive current across the battery or battery pack and simultaneously monitoring the generated AC response voltage. Specifically, the current drive circuit 200 is connected between the positive and negative terminals of the battery and is capable of generating an AC response voltage of intensity I. T The driving current flows from the negative terminal of the battery or battery pack to the positive terminal, meaning 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 operation of the battery, thus avoiding interference with the system.

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

[0040] The monitoring device 1000 disclosed herein acquires the excitation (driving current) and response (AC voltage) simultaneously within the same time window, forming a complete "excitation-response" measurement closed 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 traditional methods relying on voltage and current integration in the prior art, the monitoring device 1000 disclosed herein can more sensitively reflect the electrochemical aging process inside the battery, exhibiting higher measurement accuracy and anti-interference capability.

[0041] Continue to refer to Figure 1 In some embodiments of this disclosure, the monitoring device 1000 further includes: A 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 frequency of the first frequency. The current driving circuit 200 generates a periodic driving current (with an intensity of I) under the control of the current control signal. T ).

[0042] The modulation circuit 300 generates a current control signal with a fixed frequency, the frequency of which is a first frequency, serving as the modulation reference for the drive current. Under the action of this current control signal, the drive current (I) generated by the current drive circuit 200... T It exhibits periodic changes, for example, applied periodically to both ends of the battery or battery pack in the form of square waves, pulses or sine waves.

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

[0044] Meanwhile, the periodic drive current provides a clear time and frequency reference for subsequent signal processing, facilitating the voltage monitoring circuit to synchronously sample, filter, or demodulate the AC response voltage, thereby more accurately extracting the AC components related to the excitation signal. It is particularly suitable for monitoring batteries under dynamic operating conditions, enabling high-precision, interference-resistant detection of battery status without affecting their normal operation.

[0045] The modulation circuit can be an oscillator that can output a wave signal with a frequency of 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 wave signal output by the oscillator can be a square wave, sine wave, triangle wave, or pulse signal, and its frequency corresponds to a first frequency (ω). This wave signal serves as a current control signal, which is used directly or via 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 of this disclosure is a square wave signal.

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

[0050] refer to Figure 2 ,exist Figure 1 Based on this, the current drive circuit 200 of the monitoring device 1000 in this embodiment includes: The switching unit 201 periodically switches its on state under the control of the current control signal. The on state of the switching unit 201 causes 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 drive circuit 200. Driven by the current control signal provided by the modulation circuit 300, it periodically switches its conduction state. This change in conduction state is used to control the drive current (I0). TThe generation of ) causes the current drive circuit 200 to output a periodic drive current synchronized with the current control signal.

[0052] Through the periodic operation of the switch unit 201, the drive current alternates between "on" and "off" at a first frequency, forming an excitation signal of square wave, pulse, or other periodic waveform. This periodic switching mechanism gives the AC response signal generated by the battery clear time and frequency characteristics, making it easier to separate the effective signal from complex operating conditions.

[0053] The switching unit 201 disclosed herein may be composed of one or more electronic switches, whose switching behavior is precisely synchronized by the current control signal, ensuring the timing consistency of each excitation, improving the controllability of the drive 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 This is a schematic diagram of the circuit structure of a current drive circuit 200 according to a preferred embodiment of the present disclosure.

[0055] refer to Figure 3 For the monitoring device 1000 of the above embodiments, the current driving circuit 200 of this 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] The first terminal of the first switch S1 is connected to the positive input terminal of the first operational amplifier 202, and the second terminal of the first switch S1 is connected to the negative terminal of the battery or battery pack.

[0058] The first terminal of the second switch S2 is connected to the output terminal of the first operational amplifier 202, and the second terminal of the second switch S2 is connected to the negative terminal of the battery or battery pack.

[0059] The first terminal of the third switch S3 is connected to the positive terminal bat+ of the battery or battery pack, and the second terminal of the third switch S3 is connected to the first terminal 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 terminal bat- of the battery or battery pack.

[0061] The output terminal of the first operational amplifier 202 is also connected to the control terminal of the third switch S3 to control the conduction degree of the third switch S3 (so that it operates 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 terminal of the first switch S1 and the control terminal 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 is about Figure 3 The working process of the circuit shown will be explained.

[0065] The positive input terminal of the first operational amplifier 202 is connected to the negative terminal bat- of the battery or battery pack (typically used as reference ground, with a voltage of 0V) via a 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 shorted to the negative terminal bat- of the battery; when S1 is turned off, the reference voltage Vref is applied to 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) flowing through R0. T ·R0).

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

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

[0069] The second switch S2 is connected in series between the output of the first operational amplifier 202 and the negative terminal 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 turn on or off the connection between the reference voltage Vref and the positive input terminal of the operational amplifier, and the connection between the output terminal of the operational amplifier and 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 shorted to the negative terminal of the battery bat-; when S1 is turned off, the reference voltage Vref is applied to the positive input terminal.

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

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

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

[0075] The first operational amplifier 202 ensures that when S1 and S2 are off, I is switched on by adjusting the conduction state of S3. T The amplitude is stable, and the direction is from the negative electrode to the positive electrode.

[0076] This design is suitable for battery impedance testing or health status monitoring; the voltage monitoring circuit 100 can simultaneously measure the drive current I. T The AC response voltage of a battery under certain conditions is used to analyze its internal resistance or state.

[0077] Preferably, the first switch S1, the second switch S2 and the third switch S3 of the switch section 201 described in this disclosure are all field-effect transistor switches.

[0078] Any selection or modification of the number and type of switch section 201 by those skilled in the art based on the technical solutions disclosed herein shall fall within the protection scope of this disclosure.

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

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

[0081] Wherein, the first end of the first isolation capacitor C1 is used to connect to the positive terminal 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] The first end of the second isolation capacitor C2 is used to connect to the negative terminal of the battery or battery pack, and the second end of the second isolation capacitor C2 is connected to the positive input terminal of the fully differential operational amplifier 110.

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

[0084] The two ends of the second bridging 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 and negative output terminals of the fully differential operational amplifier 110 are used to output the AC response voltage (Vout) after 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 bridging resistor and the second bridging resistor are equal.

[0087] The following text is about Figure 4 The operation of the voltage monitoring circuit 100 shown will be explained.

[0088] The voltage monitoring circuit 100 is used to accurately extract the AC response voltage (Vin,ac) generated by the battery or battery pack under the action of periodic drive current, and amplify it for subsequent analog-to-digital conversion and analysis. Since the battery itself has a high DC voltage, and the AC response signal to be measured is very weak relative 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 through.

[0089] To address this, this disclosure provides a first isolation capacitor C1 and a second isolation capacitor C2, connected in series between the positive terminal of the battery and the negative input terminal of the fully differential operational amplifier 110, and between the negative terminal of the battery and the positive input terminal, respectively, forming an AC coupling structure. This design blocks the transmission of the battery's DC voltage to the amplifier's input terminal, allowing only the AC response voltage signal caused by the drive current to pass through, thus forming an RC high-pass filter characteristic, effectively protecting the subsequent circuitry and achieving DC isolation.

[0090] The fully differential operational amplifier 110, together with the first bridging resistor R1 and the second bridging resistor R2, constitutes a negative feedback amplifier circuit. R1 connects the negative input terminal to the positive output terminal, and 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, outputting 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 anti-interference capability. Furthermore, the differential output format facilitates direct interfacing with differential ADC circuits, reducing signal loss and increasing dynamic range. In addition, the symmetrical circuit design helps to offset errors caused by device parameter mismatch, further enhancing measurement stability.

[0092] Preferably, the first isolation capacitors C1 and C2 have equal capacitance values, and the first bridging resistors R1 and R2 have equal resistance values. This symmetrical design ensures the matching of the differential channels, which is beneficial for improving the common-mode rejection ratio (CMRR) and ensuring the linearity and consistency of the signal amplification process.

[0093] In summary, the voltage monitoring circuit 100 achieves DC isolation and AC coupling through C1 and C2. Combined with the 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 a reliable data foundation for subsequent analysis of battery internal resistance, state of health (SOH), or state of charge (SOC). This circuit is particularly suitable for online battery impedance measurement scenarios under high noise and dynamic operating conditions.

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

[0095] refer to Figure 5 Preferably, the voltage monitoring circuit 100 of this disclosure further includes: The ADC circuit 120 acquires the amplified AC response voltage (Vout) and converts it into a digital voltage signal (which is also periodic). The signal output by the ADC circuit 120 is a periodic digital voltage signal, which 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 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 synchronously samples and performs analog-to-digital conversion on them to generate a digital voltage signal corresponding to the input signal (i.e., the AC response voltage signal).

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

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

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

[0101] Continue to refer to Figure 5 In a preferred embodiment of this disclosure, the monitoring device 1000 further includes: The demodulation circuit 400 has a demodulation frequency 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. The demodulated voltage signal 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 driving 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, and its demodulation frequency is strictly consistent with the frequency of the current control signal (i.e., the first frequency ω) generated by the modulation circuit 300.

[0103] The working principle of synchronous demodulation is to multiply a periodic digital voltage signal with a reference signal whose frequency and phase are the same as the original excitation signal. Since the AC response signal of the battery has a definite phase relationship with the drive current, while environmental noise is usually a random signal, synchronous demodulation can separate the target signal from the noise.

[0104] In this disclosure, the demodulation circuit 400 receives a periodic digital voltage signal from the ADC circuit 120 and performs demodulation processing using a reference signal synchronized with the modulation circuit 300. The demodulated output voltage signal mainly contains two components: one is an AC response component with the same frequency as the drive current, i.e., the required effective signal; the other is a high-frequency component with a frequency of 2ω. Through subsequent low-pass filtering, the high-frequency component can be filtered out, retaining the effective DC or low-frequency signal, the amplitude of which is proportional to the AC impedance of the battery at frequency ω.

[0105] Preferably, the demodulation circuit 400 can be implemented digitally and integrated into a microcontroller or digital signal processor, making it easy to integrate with existing BMS systems.

[0106] The demodulation circuit 400 can adopt existing demodulation circuit structures, all of which fall within the protection scope of this disclosure.

[0107] Continue to refer to Figure 5 Preferably, the monitoring device 1000 of this 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, which is used at least 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 effective signals that characterize the battery impedance. Specifically, the cutoff frequency of the low-pass filter 500 can be set to a frequency lower than the second harmonic component (2ω) generated during demodulation, but higher than the system noise frequency, thereby effectively filtering out high-frequency interference and retaining DC or low-frequency signals directly related to battery impedance.

[0109] During synchronous demodulation, due to the characteristics of multiplication, the demodulated signal contains two main components: an AC response component (i.e., the effective signal) with the same frequency as the driving current, and a high-frequency component with a frequency of 2ω. The amplitude of the effective signal is proportional to the AC impedance of the battery at the excitation frequency ω, while the high-frequency component is a byproduct of the demodulation process, contributing nothing to impedance measurement and potentially introducing errors. Low-pass filtering can remove the high-frequency component, retaining only the DC or low-frequency components directly related to impedance information.

[0110] The amplitude of the DC voltage signal or low-frequency signal output by the low-pass filter 500 directly reflects the AC impedance of the battery 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 state of health (SOH) of the battery. For example, as the battery ages, its internal resistance typically increases, resulting in a corresponding increase in the amplitude of this signal.

[0111] Preferably, the cutoff frequency of the low-pass filter 500 is optimized according to the actual application scenario. In battery impedance measurement, it is usually set between ω / 10 and ω / 100, which can effectively filter out the 2ω component without excessively attenuating the effective signal. This filter can be an analog RC low-pass filter or a digital FIR or IIR filter, which can be flexibly selected according to system requirements.

[0112] Through processing by the low-pass filter 500, the monitoring device 1000 of this disclosure can output a stable and reliable signal that directly characterizes the impedance characteristics of the battery, providing crucial data support for battery health status 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 minute impedance changes.

[0113] For example, Vout can be represented 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 value of isolation capacitor C1 or C2, and R is the resistance value of transimpedance amplifier R1 or R2, i.e., 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, meaning 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|, demodulating it using the demodulation circuit 400 of this disclosure allows it to be 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] Among them, “(Vref / R0)·(N·Rint)·cos3ωt·∣3ω·RC∣·A3” +(Vref / R0)·(N·Rint)·cos5ωt·∣5ω·RC∣·A5 +… can be filtered out by a low-pass filter 500, and the cutoff frequency of the low-pass filter can be set to ω / 10.

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

[0123] Since the driving current of this disclosure is a periodic signal, and preferably a square wave signal, the Fourier series of the square wave contains only the cosine terms of the 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] In Vout = (Vref / R0)·(N·Rint)·cosωt·∣ω·RC∣·A1, (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 This is a schematic diagram of the monitoring device according to another embodiment of the present disclosure.

[0128] refer to Figure 6 The monitoring device 1000 also includes: The calculation and judgment module 600 executes a computer program to judge the signal output by the low-pass filter 500, and judges 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 make any special limitation in this regard, and all such cases fall within the protection scope of this disclosure.

[0130] In practical applications, the calculation and judgment module 600 can perform one or more of the following functions: Real-time monitoring and recording of battery impedance change trends; When the impedance exceeds a preset threshold, an early warning or protection mechanism is triggered. By combining parameters such as temperature and charge / discharge history, a more accurate health status assessment can be provided; Generate battery status reports for system diagnostics or user prompts.

[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 separate signal processing unit. This module can be in the form of an application-specific integrated circuit (ASIC), microcontroller (MCU), digital signal processor (DSP), or field-programmable gate array (FPGA), etc., flexibly selected according to the actual application scenario. Regardless of the implementation method, its core function is to convert physical measurement signals into meaningful battery state information, providing a basis for decision-making regarding battery safety and lifespan management.

[0132] This disclosure also provides a battery system, including: a battery or a battery pack; and a monitoring device 1000 according to any embodiment of this disclosure, the monitoring device 1000 being used to monitor the battery or battery pack.

[0133] This disclosure also provides an electrical device including a battery system according to any embodiment of this disclosure.

[0134] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[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 indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0136] Those skilled in the art should understand that the above embodiments are merely for illustrating the present disclosure and are not intended to limit the scope of the disclosure. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present disclosure.

Claims

1. A monitoring device for monitoring a battery or battery pack, characterized by include: A voltage monitoring circuit is provided for connection between the positive and negative terminals of the battery or battery pack. as well as A current driving circuit is used to connect between the positive and negative terminals of the battery or battery pack. The current driving circuit is capable of generating a driving current that can flow into the negative terminal of the battery or battery pack and flow out from the positive terminal of the battery or battery pack. The voltage monitoring circuit is at least used to monitor the AC response voltage between the positive and negative terminals caused by the driving current when the current driving circuit generates the driving current.

2. The monitoring device of claim 1, wherein, The monitoring device also includes: A 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. The current driving circuit generates a periodic driving current under the control of the current control signal.

3. The monitoring device of claim 2, wherein, The current driving circuit includes: The switching unit periodically switches its conduction state under the control of the current control signal, and the conduction state of the switching unit causes the current driving circuit to generate a periodic driving current.

4. The monitoring device of claim 2, wherein, The modulation circuit is an oscillator that can output a wave signal with a first frequency as the current control signal.

5. The monitoring device of claim 3, wherein, The current driving circuit further includes: a first operational amplifier and a first resistor; The switching unit includes a first switch, a second switch, and a third switch; The first terminal of the first switch is connected to the positive input terminal of the first operational amplifier, and the second terminal of the first switch is connected to the negative terminal of the battery or battery pack. The first terminal of the second switch is connected to the output terminal of the first operational amplifier, and the second terminal of the second switch is connected to the negative terminal of the battery or battery pack. The first terminal of the third switch is connected to the positive terminal of the battery or battery pack, and the second terminal of the third switch is connected to the first terminal 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 terminal of the battery or battery pack. The output terminal of the first operational amplifier is also 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 of claim 5, wherein, The current control signal synchronously controls the first switch and the second switch via the control terminals of the first switch and the second switch, so that the first switch and the second switch are turned on or off synchronously.

7. The monitoring device of claim 5, wherein, The first switch, the second switch, and the third switch are all field-effect transistor switches.

8. The monitoring device of claim 1, wherein, The voltage monitoring circuit includes: a first isolation capacitor, a second isolation capacitor, a fully differential operational amplifier, a first bridging resistor, and a second bridging resistor; The first end of the first isolation capacitor is used to connect to the positive terminal 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 terminal 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. The two ends of the first bridging resistor are respectively connected to the negative input terminal and the positive output terminal of the fully differential operational amplifier; The two ends of the second bridging resistor are respectively connected to the positive input terminal and the negative output terminal of the fully differential operational amplifier; The positive and negative output terminals of the fully differential operational amplifier are used to output the amplified AC response voltage.

9. The monitoring device of claim 8, wherein, The first isolation capacitor and the second isolation capacitor have the same capacitance value, and the first bridging resistor and the second bridging resistor have the same resistance value.

10. The monitoring device of claim 8, wherein, The voltage monitoring circuit also includes: An ADC circuit is included, which acquires 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, which is used to monitor the battery or battery pack.

11. The monitoring device of claim 10, wherein, The monitoring device also includes: The demodulation circuit has a demodulation frequency 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. The demodulated voltage signal is an AC response component with the same frequency as the driving current.

12. The monitoring device of claim 11, wherein, The monitoring device also includes: A low-pass filter performs low-pass filtering on the demodulated voltage signal and outputs a DC voltage signal or a low-frequency signal, which is used at least to characterize the impedance of the battery or battery pack.

13. The monitoring device of claim 2, wherein, The current control signal is a square wave signal.

14. A battery system characterized by, include: Battery or battery pack; as well as The monitoring device according to any one of claims 1 to 13, wherein the monitoring device is used to monitor the battery or battery pack.

15. An electrical device, characterized by Includes the battery system of claim 14.

Images