Battery online electrochemical impedance measuring device and method based on coherent detection

Abstract

The invention provides a device and a method for measuring online electrochemical impedance of a battery based on coherent detection in the technical field of electrochemical detection and battery state monitoring. The device comprises a microcontroller, a first analog-to-digital converter, a second analog-to-digital converter, a first signal amplifier, a second signal amplifier, a first low-pass filter, a second low-pass filter, a first analog multiplier, a second analog multiplier, a third analog multiplier, a voltage detection circuit and a current detection circuit. The device comprises a first pre-charging circuit, a second pre-charging circuit, a first blocking circuit, a second blocking circuit, a carrier signal generation circuit, a baseband signal generation circuit and a power amplification circuit. The method has the advantages that the capability of extracting weak response signals is improved, so that the high-precision online measurement of the milliohm-magnitude micro-impedance of the battery in a complex noise environment is realized.

Description

Technical Field

[0001] This invention relates to the field of electrochemical detection and battery state monitoring technology, and in particular to an online electrochemical impedance spectroscopy device and method for batteries based on coherent detection. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) is an important method for analyzing the internal characteristics of an electrochemical system by applying a small AC excitation signal and measuring its impedance response at multiple frequencies. In the battery field, especially in new energy electric vehicles and electrochemical energy storage systems, EIS can non-destructively obtain key parameters such as ohmic internal resistance, charge transfer resistance, and double-layer capacitance, making it an effective tool for assessing battery state of health (SOH), state of charge (SOC), and for early warning of faults.

[0003] However, applying EIS technology for online, real-time battery monitoring in complex industrial environments still faces significant challenges. On one hand, the environment contains strong noise sources such as motors, converters, and switching power supplies, whose background noise amplitude far exceeds the weak AC excitation signal (typically on the order of 0.1mV) injected to avoid affecting battery performance. This results in an extremely low signal-to-noise ratio (SNR) for the response signal, easily drowning out the useful signal. On the other hand, to improve the SNR, existing technologies typically employ the simple method of directly increasing the injected signal power. However, this brings significant drawbacks: it not only increases the energy consumption, cost, and size of the detection equipment, hindering miniaturization and integration, but excessive injection current may also negatively impact battery life and condition. This method fails to fundamentally solve the core problem of extracting useful signals of specific frequencies under strong background noise, and its anti-interference capability is only partially improved.

[0004] Furthermore, the high operating voltage of the battery system and the complex electromagnetic interference in the industrial environment place higher demands on the anti-interference design and dynamic range of the signal detection circuit. In particular, how to stably and accurately extract the weak battery voltage and current response signals from strong background noise without significantly increasing the excitation signal power has become a key bottleneck in achieving online, high-precision electrochemical impedance measurement.

[0005] Therefore, how to provide a battery online electrochemical impedance measurement device and method based on coherent detection to improve the ability to extract weak response signals, thereby achieving high-precision online measurement of battery milliohm-level micro-impedance in complex noise environments, has become an urgent technical problem to be solved. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an online electrochemical impedance spectroscopy device and method for batteries based on coherent detection, thereby improving the ability to extract weak response signals and realizing high-precision online measurement of the milliohm-level micro impedance of batteries in complex noise environments.

[0007] In a first aspect, the present invention provides an online electrochemical impedance spectroscopy (EIS) measurement device for a battery based on coherent detection, comprising a battery under test, characterized in that it further comprises a microcontroller, a first analog-to-digital converter, a second analog-to-digital converter, a first signal amplifier, a second signal amplifier, a first low-pass filter, a second low-pass filter, a first analog multiplier, a second analog multiplier, a third analog multiplier, a voltage detection circuit, a current detection circuit, a first pre-charge circuit, a second pre-charge circuit, a first DC blocking circuit, a second DC blocking circuit, a carrier signal generation circuit, a baseband signal generation circuit, and a power amplifier circuit; The microcontroller, the first analog-to-digital converter, the first signal amplifier, the first low-pass filter, the first analog multiplier, the voltage detection circuit, the first DC blocking circuit, and the first pre-charge circuit are connected in sequence. The microcontroller, the second analog-to-digital converter, the second signal amplifier, the second low-pass filter, the second analog multiplier, and the current detection circuit are connected in sequence. The microcontroller, baseband signal generation circuit, third analog multiplier, power amplifier circuit, second DC blocking circuit and second pre-charging circuit are connected in sequence. The input terminal of the carrier signal generating circuit is connected to the microcontroller, and the output terminal is connected to the first analog multiplier, the second analog multiplier, and the third analog multiplier. The voltage detection circuit and the current detection circuit are both connected to the negative terminal of the battery under test, and the first pre-charging circuit and the second pre-charging circuit are both connected to the positive terminal of the battery under test.

[0008] Furthermore, the carrier signal generating circuit is used to generate a high-frequency carrier signal and is composed of a DDS chip, a crystal oscillator, or a resonant circuit.

[0009] Furthermore, the baseband signal generation circuit is used to generate an AC baseband signal that is injected into the battery under test.

[0010] Furthermore, the first analog multiplier, the second analog multiplier, and the third analog multiplier are all used to output AM modulated signals.

[0011] Furthermore, the power amplifier circuit is a voltage-to-current conversion circuit composed of a power amplifier to convert AC signals into constant current source excitation signals.

[0012] Furthermore, both the first DC blocking circuit and the second DC blocking circuit are used to isolate the battery under test.

[0013] Furthermore, the voltage detection circuit is used to amplify the AC voltage response signal output by the battery under test through a differential operational amplifier circuit, and then output the amplified weak AC voltage response signal to the first analog multiplier for coherent demodulation.

[0014] Furthermore, the current detection circuit is used to amplify the AC current response signal output by the battery under test through a differential operational amplifier circuit, and then output the amplified weak AC current response signal to the second analog multiplier for coherent demodulation.

[0015] Secondly, the present invention provides an online electrochemical impedance spectroscopy measurement of a battery based on coherent detection, comprising the following steps: Step S1: The microcontroller generates a baseband signal with a frequency range of 10Hz to 10kHz and a carrier signal with a frequency of 1MHz through the baseband signal generation circuit and the carrier signal generation circuit, respectively. Step S2: The baseband signal and the carrier signal are coherently modulated by the third analog multiplier to generate a modulated signal; Step S3: The modulation signal is amplified by a power amplifier circuit and converted into a constant current source excitation signal, which is then injected into the battery under test through a second DC blocking circuit and a second pre-charging circuit. Step S4: Real-time detection of the AC voltage response signal and AC current response signal of the battery under test through the voltage detection circuit and the current detection circuit; Step S5: The AC voltage response signal and AC current response signal are coherently demodulated by the first analog multiplier and the second analog multiplier to obtain the baseband voltage response signal and the baseband current response signal. Step S6: The baseband voltage response signal is sequentially passed through a first low-pass filter, a first signal amplifier, and a first analog-to-digital converter to obtain a voltage digital signal input to the microcontroller; the baseband current response signal is sequentially passed through a second low-pass filter, a second signal amplifier, and a second analog-to-digital converter to obtain a current digital signal input to the microcontroller. Step S7: The microcontroller calculates the electrochemical impedance spectrum of the battery under test based on the voltage digital signal and the current digital signal.

[0016] Furthermore, both the first pre-charging circuit and the second pre-charging circuit are pre-charged to 80% of the voltage of the battery being tested.

[0017] The advantages of this invention are: 1. By employing coherent detection technology, a low-frequency baseband signal is modulated onto a high-frequency carrier and injected into the battery under test. The voltage and current response signals of the battery under test are coherently demodulated using first and second analog multipliers that are in phase and frequency with the carrier. This demodulation process is equivalent to a narrowband filter with an extremely high Q value, which can selectively extract the weak response that is strictly synchronized with the excitation signal, while greatly suppressing most of the unrelated wideband background noise. Thus, without increasing the power of the excitation signal, the high signal-to-noise ratio measurement required for milliohm-level micro-impedance is achieved.

[0018] 2. Coherent detection technology is adopted, which generates high-frequency carrier and baseband signals through carrier signal generation circuit and baseband signal generation circuit, and uses analog multipliers for coherent modulation and demodulation. This design can effectively suppress environmental noise and interference, improve the signal-to-noise ratio, and thus ensure high accuracy of electrochemical impedance measurement. For example, after the voltage detection circuit and current detection circuit amplify the weak AC response signal, it is then coherently demodulated by analog multipliers. Combined with a low-pass filter to extract the baseband signal, the measurement error is reduced, which is particularly suitable for weak signal situations in online battery monitoring.

[0019] 3. The device supports online electrochemical impedance measurement of batteries without interrupting normal battery operation, enabling real-time monitoring. The microcontroller controls the entire process, including signal generation, modulation, injection, detection, and demodulation, and calculates the impedance spectrum in real time. This method allows for continuous data acquisition while the battery is in operation, avoiding downtime caused by traditional offline measurements, improving efficiency, and is suitable for applications requiring continuous monitoring, such as electric vehicles and energy storage systems.

[0020] 4. The baseband signal generation circuit can generate a baseband signal with a frequency range of 10Hz to 10kHz. Combined with a 1MHz carrier signal, this allows measurements to be performed at multiple frequency points, thereby obtaining a comprehensive electrochemical impedance spectrum. This wide frequency range covers the key frequency bands of the battery's electrochemical response, which helps to analyze the battery's state (such as aging and changes in internal resistance). The microcontroller can adjust the signal parameters through programming, enhancing the flexibility and applicability of the measurement.

[0021] 5. It integrates DC blocking circuits (such as the first DC blocking circuit and the second DC blocking circuit) and pre-charging circuits (such as the first pre-charging circuit and the second pre-charging circuit), which can effectively isolate the DC component of the battery and prevent damage to the measurement circuit from overvoltage or current surges; the pre-charging circuit pre-charges to 80% of the battery voltage, reducing transient surges and ensuring the safety and stability of the measurement process, making it particularly suitable for high-voltage or high-capacity battery systems.

[0022] 6. It adopts a clear modular structure, and the components (such as analog-to-digital converters, signal amplifiers, low-pass filters, etc.) work in coordination through a microcontroller, achieving a high degree of integration. This design facilitates system maintenance, upgrades, and mass production, while reducing external interference and improving reliability. For example, the voltage and current detection channels are independent but symmetrical, ensuring the consistency of signal processing and reducing design complexity.

[0023] 7. The power amplifier circuit converts the modulation signal into a constant current source excitation signal. The voltage-to-current conversion circuit ensures the stability of the current injected into the battery, avoiding excitation signal fluctuations caused by changes in the battery's internal resistance. This constant current source design improves the consistency and repeatability of measurements, making impedance calculation results more accurate, and is especially suitable for comparing batteries in different states.

[0024] 8. The microcontroller processes digital signals in real time during the measurement process (acquiring voltage and current digital signals through an analog-to-digital converter) and quickly calculates the electrochemical impedance spectrum, reducing data processing delay. This method supports high-speed monitoring and feedback, is suitable for dynamic control of battery management systems, and improves overall measurement efficiency.

[0025] 9. By using the principle of coherent detection, combined with high-frequency carrier modulation and demodulation, dual-channel signal processing and modular circuit design, high-precision online measurement of battery electrochemical impedance is achieved. It has excellent noise resistance and wide bandwidth adaptability. Its integrated DC blocking and pre-charging circuit ensures measurement safety. The real-time process controlled by the microcontroller does not require interruption of battery operation, which significantly improves monitoring efficiency and practicality. The overall solution ensures stability while taking into account cost-effectiveness. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a circuit block diagram of an online electrochemical impedance spectroscopy (EIS) measurement device for batteries based on coherent detection, according to the present invention.

[0028] Figure 2 This is a flowchart of an online electrochemical impedance spectroscopy method for batteries based on coherent detection, according to the present invention. Detailed Implementation

[0029] Please refer to Figures 1 to 2As shown, a preferred embodiment of the online electrochemical impedance spectroscopy (EIS) measurement device for batteries based on coherent detection according to the present invention includes a battery under test, characterized in that it further includes a microcontroller, a first analog-to-digital converter, a second analog-to-digital converter, a first signal amplifier, a second signal amplifier, a first low-pass filter, a second low-pass filter, a first analog multiplier, a second analog multiplier, a third analog multiplier, a voltage detection circuit, a current detection circuit, a first pre-charge circuit, a second pre-charge circuit, a first DC blocking circuit, a second DC blocking circuit, a carrier signal generation circuit, a baseband signal generation circuit, and a power amplifier circuit; As the control core of the entire device, a microcontroller (MCU) or DSP chip with digital signal processing capabilities is preferred, such as STMicroelectronics' STM32F4 series or Texas Instruments' TMS320F28xxx series. It is responsible for coordinating signal generation, data acquisition, computation, and communication processes. Specifically, the microcontroller precisely controls the frequency and phase of the baseband and carrier signals through built-in timers or DMA controllers, and configures and manages peripheral devices such as analog-to-digital converters and signal generation circuits through interfaces such as SPI or I2C.

[0030] The carrier signal generation circuit can use a direct digital frequency synthesizer chip (such as AD9834) to generate a high-frequency carrier signal (such as 1MHz) with stable frequency and continuous phase. Its output signal can be processed by a buffer amplification stage composed of an operational amplifier (such as OPA657) to provide sufficient driving capability and match the input impedance of the subsequent multiplier.

[0031] The baseband signal generation circuit can be directly generated by the DAC output port of a microcontroller, or a dedicated waveform generation chip (such as AD9102) can be used. The generated baseband signal frequency can be scanned in logarithmic or linear steps within the range of 10Hz to 10kHz in order to obtain a complete electrochemical impedance spectrum.

[0032] The first, second, and third analog multipliers can be integrated analog multiplier chips, such as the AD633. To ensure the accuracy of coherent detection, the carrier signals injected into the three multipliers must maintain a strict in-phase and frequency relationship. In actual wiring, the length of the carrier signal transmission path should be matched, or a phase adjustment circuit should be used for compensation.

[0033] The voltage detection circuit preferably uses a high-precision, low-noise instrumentation amplifier (such as INA128) to form a differential amplifier circuit, which is directly connected to the two ends of the battery (attention should be paid to the isolation of common-mode voltage). This circuit amplifies the microvolt-level AC voltage response signal to the volt level for subsequent demodulation.

[0034] The current detection circuit preferably uses a precision sampling resistor (e.g., milliohm level) connected in series in the loop, along with a differential amplifier, to detect the current signal. Similarly, a low-noise operational amplifier should be selected, and attention should be paid to the power tolerance and temperature drift characteristics of the sampling resistor.

[0035] The core component of the DC blocking circuit is a high-voltage, non-polarized capacitor (such as a CBB capacitor). Its voltage rating must be higher than the battery's maximum operating voltage, and the capacitance selection must ensure low impedance to the lowest baseband signal frequency (such as 10Hz). For example, for a 10Hz signal, the capacitive reactance should be much smaller than the input impedance of subsequent circuits.

[0036] The pre-charge circuit consists of a pre-charge resistor and a relay (or a high-voltage MOSFET). Initially, the relay is open, allowing the DC-blocking capacitor to be charged with current-limited speed through the pre-charge resistor. When the voltage across the capacitor reaches approximately 80% of the battery voltage (this value is adjustable), the microcontroller controls the relay to close, directly connecting the circuit to reduce ongoing losses. The pre-charge process effectively prevents the large current surge generated during the initial charging of the capacitor.

[0037] The first and second low-pass filters are preferably Butterworth or Chebyshev active low-pass filters composed of multi-stage operational amplifiers, with a cutoff frequency slightly higher than the highest frequency of the baseband signal (e.g., 12kHz) to effectively filter out high-frequency components (mainly twice the carrier frequency and its sideband components) in the demodulated signal without significantly attenuating the baseband signal.

[0038] The first and second analog-to-digital converters should be high-resolution (e.g., 16 bits or more) and high-sampling-rate ADC chips (e.g., ADS8881). The sampling rate must satisfy the Nyquist sampling theorem; for baseband signals up to 10kHz, the sampling rate is typically set to 50kSPS or higher.

[0039] The microcontroller, the first analog-to-digital converter, the first signal amplifier, the first low-pass filter, the first analog multiplier, the voltage detection circuit, the first DC blocking circuit, and the first pre-charge circuit are connected in sequence. The microcontroller, the second analog-to-digital converter, the second signal amplifier, the second low-pass filter, the second analog multiplier, and the current detection circuit are connected in sequence. The microcontroller, baseband signal generation circuit, third analog multiplier, power amplifier circuit, second DC blocking circuit and second pre-charging circuit are connected in sequence. The input terminal of the carrier signal generating circuit is connected to the microcontroller, and the output terminal is connected to the first analog multiplier, the second analog multiplier, and the third analog multiplier. The voltage detection circuit and the current detection circuit are both connected to the negative terminal of the battery under test, and the first pre-charging circuit and the second pre-charging circuit are both connected to the positive terminal of the battery under test.

[0040] The carrier signal generating circuit is used to generate a high-frequency carrier signal and consists of a DDS chip, a crystal oscillator, or a resonant circuit. To improve the signal carrying capacity and adjust the output impedance, an amplifier circuit can be added before the carrier signal output stage.

[0041] The baseband signal generation circuit is used to generate an AC baseband signal that is injected into the battery under test.

[0042] The first, second, and third analog multipliers are all used to output AM modulated signals. The carrier signal input to the modulation circuit must maintain phase and frequency consistency with the carrier signal input to the demodulation circuit.

[0043] The power amplifier circuit is a voltage-to-current conversion circuit composed of a power amplifier to convert AC signals into constant current source excitation signals.

[0044] Both the first DC blocking circuit and the second DC blocking circuit are used to isolate the battery under test.

[0045] The voltage detection circuit is used to amplify the AC voltage response signal output by the battery under test through a differential operational amplifier circuit. The amplified AC voltage response signal is then output to the first analog multiplier for coherent demodulation.

[0046] The current detection circuit is used to amplify the AC current response signal output by the battery under test through a differential operational amplifier circuit. The amplified AC current response signal is then output to the second analog multiplier for coherent demodulation.

[0047] The DC blocking circuit and pre-charging circuit mainly consist of a high-voltage DC blocking capacitor, a power resistor, and a high-voltage relay. Since automotive batteries are high-voltage DC power supplies, they must be coupled through a high-voltage DC blocking circuit to prevent high-voltage damage to circuit components.

[0048] A low-pass filter is composed of multiple low-pass sub-filters, each with a different center frequency. The demodulated signal consists of high-frequency signals and baseband AC signals. After being filtered stage by stage by the low-pass filter, the baseband AC signal is retained at the output.

[0049] The baseband AC signal is amplified by a signal amplifier to meet the signal requirements of the ADC sampling; the signal amplification circuit plays a key role in adjusting the input impedance before the signal is input to the analog-to-digital converter.

[0050] The analog-to-digital converter (ADC) consists of a high-precision, high-speed ADC chip that converts analog signals with voltage and current responses into digital signals, which are then sent to the microcontroller via a data transmission port. The microcontroller unit receives voltage and current response data and calculates the electrochemical impedance spectrum using a model of voltage, current, and their phase relationship.

[0051] A preferred embodiment of the present invention provides a method for online electrochemical impedance spectroscopy of batteries based on coherent detection, comprising the following steps: Step S1: The microcontroller generates a baseband signal with a frequency range of 10Hz to 10kHz and a carrier signal with a frequency of 1MHz through the baseband signal generation circuit and the carrier signal generation circuit, respectively. Microcontrollers can generate digital baseband and carrier signal waveform data through software algorithms (such as lookup table method or direct calculation method), and then convert them into analog signals through DAC; Step S2: The baseband signal and the carrier signal are coherently modulated by the third analog multiplier to generate a modulated signal; Step S3: The modulation signal is amplified by a power amplifier circuit and converted into a constant current source excitation signal, which is then injected into the battery under test through a second DC blocking circuit and a second pre-charging circuit. Step S4: Real-time detection of the AC voltage response signal and AC current response signal of the battery under test through the voltage detection circuit and the current detection circuit; Step S5: The AC voltage response signal and AC current response signal are coherently demodulated by the first analog multiplier and the second analog multiplier to obtain the baseband voltage response signal and the baseband current response signal. Since the injected battery excitation signal is a baseband excitation after coherent modulation, the AC voltage response signal and AC current response signal of the baseband signal are obtained by coherent demodulation technology in the detection circuit. The detection accuracy can still be ensured while maintaining an extremely low signal-to-noise ratio and extremely low power consumption, which demonstrates the super anti-interference capability.

[0052] Step S6: The baseband voltage response signal is sequentially passed through a first low-pass filter, a first signal amplifier, and a first analog-to-digital converter to obtain a voltage digital signal input to the microcontroller; the baseband current response signal is sequentially passed through a second low-pass filter, a second signal amplifier, and a second analog-to-digital converter to obtain a current digital signal input to the microcontroller. Step S7: The microcontroller calculates the electrochemical impedance spectrum of the battery under test based on the voltage digital signal and the current digital signal.

[0053] Both the first pre-charging circuit and the second pre-charging circuit are pre-charged to 80% of the voltage of the battery under test. After the circuit is turned on, the first pre-charging circuit and the second pre-charging circuit can be disconnected.

[0054] In summary, the advantages of this invention are: 1. By employing coherent detection technology, a low-frequency baseband signal is modulated onto a high-frequency carrier and injected into the battery under test. The voltage and current response signals of the battery under test are coherently demodulated using first and second analog multipliers that are in phase and frequency with the carrier. This demodulation process is equivalent to a narrowband filter with an extremely high Q value, which can selectively extract the weak response that is strictly synchronized with the excitation signal, while greatly suppressing most of the unrelated wideband background noise. Thus, without increasing the power of the excitation signal, the high signal-to-noise ratio measurement required for milliohm-level micro-impedance is achieved.

[0055] 2. Coherent detection technology is adopted, which generates high-frequency carrier and baseband signals through carrier signal generation circuit and baseband signal generation circuit, and uses analog multipliers for coherent modulation and demodulation. This design can effectively suppress environmental noise and interference, improve the signal-to-noise ratio, and thus ensure high accuracy of electrochemical impedance measurement. For example, after the voltage detection circuit and current detection circuit amplify the weak AC response signal, it is then coherently demodulated by analog multipliers. Combined with a low-pass filter to extract the baseband signal, the measurement error is reduced, which is particularly suitable for weak signal situations in online battery monitoring.

[0056] 3. The device supports online electrochemical impedance measurement of batteries without interrupting normal battery operation, enabling real-time monitoring. The microcontroller controls the entire process, including signal generation, modulation, injection, detection, and demodulation, and calculates the impedance spectrum in real time. This method allows for continuous data acquisition while the battery is in operation, avoiding downtime caused by traditional offline measurements, improving efficiency, and is suitable for applications requiring continuous monitoring, such as electric vehicles and energy storage systems.

[0057] 4. The baseband signal generation circuit can generate a baseband signal with a frequency range of 10Hz to 10kHz. Combined with a 1MHz carrier signal, this allows measurements to be performed at multiple frequency points, thereby obtaining a comprehensive electrochemical impedance spectrum. This wide frequency range covers the key frequency bands of the battery's electrochemical response, which helps to analyze the battery's state (such as aging and changes in internal resistance). The microcontroller can adjust the signal parameters through programming, enhancing the flexibility and applicability of the measurement.

[0058] 5. It integrates DC blocking circuits (such as the first DC blocking circuit and the second DC blocking circuit) and pre-charging circuits (such as the first pre-charging circuit and the second pre-charging circuit), which can effectively isolate the DC component of the battery and prevent damage to the measurement circuit from overvoltage or current surges; the pre-charging circuit pre-charges to 80% of the battery voltage, reducing transient surges and ensuring the safety and stability of the measurement process, making it particularly suitable for high-voltage or high-capacity battery systems.

[0059] 6. It adopts a clear modular structure, and the components (such as analog-to-digital converters, signal amplifiers, low-pass filters, etc.) work in coordination through a microcontroller, achieving a high degree of integration. This design facilitates system maintenance, upgrades, and mass production, while reducing external interference and improving reliability. For example, the voltage and current detection channels are independent but symmetrical, ensuring the consistency of signal processing and reducing design complexity.

[0060] 7. The power amplifier circuit converts the modulation signal into a constant current source excitation signal. The voltage-to-current conversion circuit ensures the stability of the current injected into the battery, avoiding excitation signal fluctuations caused by changes in the battery's internal resistance. This constant current source design improves the consistency and repeatability of measurements, making impedance calculation results more accurate, and is especially suitable for comparing batteries in different states.

[0061] 8. The microcontroller processes digital signals in real time during the measurement process (acquiring voltage and current digital signals through an analog-to-digital converter) and quickly calculates the electrochemical impedance spectrum, reducing data processing delay. This method supports high-speed monitoring and feedback, is suitable for dynamic control of battery management systems, and improves overall measurement efficiency.

[0062] 9. By using the principle of coherent detection, combined with high-frequency carrier modulation and demodulation, dual-channel signal processing and modular circuit design, high-precision online measurement of battery electrochemical impedance is achieved. It has excellent noise resistance and wide bandwidth adaptability. Its integrated DC blocking and pre-charging circuit ensures measurement safety. The real-time process controlled by the microcontroller does not require interruption of battery operation, which significantly improves monitoring efficiency and practicality. The overall solution ensures stability while taking into account cost-effectiveness.

[0063] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A battery online electrochemical impedance spectroscopy device based on coherent detection, comprising a battery under test, characterized in that: It also includes a microcontroller, a first analog-to-digital converter, a second analog-to-digital converter, a first signal amplifier, a second signal amplifier, a first low-pass filter, a second low-pass filter, a first analog multiplier, a second analog multiplier, a third analog multiplier, a voltage detection circuit, a current detection circuit, a first pre-charge circuit, a second pre-charge circuit, a first DC blocking circuit, a second DC blocking circuit, a carrier signal generation circuit, a baseband signal generation circuit, and a power amplifier circuit; The microcontroller, the first analog-to-digital converter, the first signal amplifier, the first low-pass filter, the first analog multiplier, the voltage detection circuit, the first DC blocking circuit, and the first pre-charge circuit are connected in sequence. The microcontroller, the second analog-to-digital converter, the second signal amplifier, the second low-pass filter, the second analog multiplier, and the current detection circuit are connected in sequence. The microcontroller, baseband signal generation circuit, third analog multiplier, power amplifier circuit, second DC blocking circuit and second pre-charging circuit are connected in sequence. The input terminal of the carrier signal generating circuit is connected to the microcontroller, and the output terminal is connected to the first analog multiplier, the second analog multiplier, and the third analog multiplier. The voltage detection circuit and the current detection circuit are both connected to the negative terminal of the battery under test, and the first pre-charging circuit and the second pre-charging circuit are both connected to the positive terminal of the battery under test.

2. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The carrier signal generating circuit is used to generate high-frequency carrier signals and is composed of a DDS chip, a crystal oscillator, or a resonant circuit.

3. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The baseband signal generation circuit is used to generate an AC baseband signal that is injected into the battery under test.

4. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The first analog multiplier, the second analog multiplier, and the third analog multiplier are all used to output AM modulated signals.

5. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The power amplifier circuit is a voltage-to-current conversion circuit composed of a power amplifier to convert AC signals into constant current source excitation signals.

6. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: Both the first DC blocking circuit and the second DC blocking circuit are used to isolate the battery under test.

7. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The voltage detection circuit is used to amplify the AC voltage response signal output by the battery under test through a differential operational amplifier circuit. The amplified AC voltage response signal is then output to the first analog multiplier for coherent demodulation.

8. The online electrochemical impedance spectroscopy device for batteries based on coherent detection as described in claim 1, characterized in that: The current detection circuit is used to amplify the AC current response signal output by the battery under test through a differential operational amplifier circuit. The amplified AC current response signal is then output to the second analog multiplier for coherent demodulation.

9. A method for online electrochemical impedance spectroscopy of a battery based on coherent detection, characterized in that: The method requires the use of the testing apparatus as described in any one of claims 1 to 8 and includes the following steps: Step S1: The microcontroller generates a baseband signal with a frequency range of 10Hz to 10kHz and a carrier signal with a frequency of 1MHz through the baseband signal generation circuit and the carrier signal generation circuit, respectively. Step S2: The baseband signal and the carrier signal are coherently modulated by the third analog multiplier to generate a modulated signal; Step S3: The modulation signal is amplified by a power amplifier circuit and converted into a constant current source excitation signal, which is then injected into the battery under test through a second DC blocking circuit and a second pre-charging circuit. Step S4: Real-time detection of the AC voltage response signal and AC current response signal of the battery under test through the voltage detection circuit and the current detection circuit; Step S5: The AC voltage response signal and AC current response signal are coherently demodulated by the first analog multiplier and the second analog multiplier to obtain the baseband voltage response signal and the baseband current response signal. Step S6: The baseband voltage response signal passes sequentially through a first low-pass filter, a first signal amplifier, and a first analog-to-digital converter to obtain a voltage digital signal input to the microcontroller; The baseband current response signal is sequentially passed through a second low-pass filter, a second signal amplifier, and a second analog-to-digital converter to obtain a digital current signal input to the microcontroller; Step S7: The microcontroller calculates the electrochemical impedance spectrum of the battery under test based on the voltage digital signal and the current digital signal.

10. The method for online electrochemical impedance spectroscopy of a battery based on coherent detection as described in claim 9, characterized in that: Both the first pre-charging circuit and the second pre-charging circuit are pre-charged to 80% of the voltage of the battery being tested.

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