Common-mode voltage direct-current component extraction circuit and method based on adaptive filter

Abstract

The invention relates to the field of sampling circuits, and provides a common-mode voltage direct-current component extraction circuit and method based on an adaptive filter, and the circuit comprises a precision resistance voltage division circuit which is used for obtaining a common-mode voltage, and the input end of the precision resistance voltage division circuit is connected with the positive electrode and the negative electrode of a direct-current bus; the input end of the alternating-current acquisition branch is connected with the first output end of the precision resistance voltage division circuit, and the alternating-current acquisition branch is used for acquiring an alternating-current voltage component; the input end of the direct-current extraction branch is connected with the second output end of the precision resistance voltage division circuit, and the direct-current extraction branch is used for collecting a direct-current voltage component; the input end of the micro-control unit is connected with the output end of the alternating current acquisition branch and the output end of the direct current extraction branch, the output end of the micro-control unit is connected with the input end of the direct current extraction branch through a communication interface, and the micro-control unit is used for adjusting the cut-off frequency of the adaptive filter.

Description

Technical Field

[0001] This invention relates to the field of sampling circuits, and more particularly to a common-mode voltage DC component extraction circuit and method based on an adaptive filter. Background Technology

[0002] In power electronic systems, monitoring the DC bus voltage status of devices such as energy storage converters is crucial. Common-mode voltage, a key parameter of the DC bus voltage, requires accurate extraction of its DC component for insulation testing. Traditional methods for extracting the DC component of common-mode voltage often employ filters with fixed parameters, such as RC (Resistor-Capacitor) low-pass filters. However, in practical applications, the operating environment of power electronic systems is complex and variable; temperature variations, equipment aging, and other factors can alter parasitic parameters on the DC side.

[0003] When parasitic parameters change, the filter's cutoff frequency and other characteristics no longer match the actual signal, and the AC component cannot be effectively filtered out. This results in a large error in the extracted DC component, affecting the accuracy of operations such as insulation level prediction. Furthermore, traditional methods lack adaptive adjustment capabilities when dealing with complex and variable signal frequency components, and cannot accurately extract the DC component of the common-mode voltage under different operating conditions. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a common-mode voltage DC component extraction circuit and method based on an adaptive filter, which accurately extracts the DC component of the common-mode voltage under different operating conditions.

[0005] To achieve the above objectives, this invention proposes a common-mode voltage DC component extraction circuit based on an adaptive filter, comprising: A precision resistor voltage divider circuit, the input terminals of which are connected to the positive and negative terminals of the DC bus, is used to obtain the common-mode voltage; The AC acquisition branch has its input terminal connected to the first output terminal of the precision resistor voltage divider circuit, and is used to acquire AC voltage components. The DC extraction branch has its input terminal connected to the second output terminal of the precision resistor voltage divider circuit, and is used to collect the DC voltage component. The microcontroller unit has its input terminals connected to the output terminals of the AC acquisition branch and the DC extraction branch. The output terminal of the microcontroller unit is connected to the input terminal of the DC extraction branch through a communication interface and is used to adjust the cutoff frequency of the adaptive filter.

[0006] In some embodiments, the AC acquisition branch includes a DC blocking circuit, a first differential amplifier circuit, and a first voltage follower; The output of the precision resistor voltage divider circuit is connected to the input of the DC blocking circuit; The output of the DC blocking circuit is connected to the input of the first differential amplifier circuit; The output of the first differential amplifier circuit is connected to the input of the first voltage follower; The output of the first voltage follower is connected to the first analog-to-digital converter of the microcontroller; The DC blocking circuit extracts the common-mode voltage to obtain AC data, which is then amplified by the first differential amplifier circuit to the acquisition range of the first analog-to-digital converter. After passing through the first voltage follower, the first analog-to-digital converter samples the AC voltage component.

[0007] In some embodiments, the first differential amplifier circuit includes a first operational amplifier, a first input resistor, a second input resistor, a first feedback resistor, a first grounding resistor, and a first output resistor; The output terminal of the DC blocking circuit is connected to one end of the first input resistor, the other end of the first input resistor is connected to the inverting input terminal of the first operational amplifier and the first grounding resistor respectively, and the other end of the first operational amplifier is connected to the first output resistor; The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier for negative feedback. The DC blocking circuit transmits AC data to the inverting input of the first operational amplifier; the first operational amplifier amplifies the AC data; and the first feedback resistor feeds the AC data back to the differential input of the first operational amplifier.

[0008] In some embodiments, the DC extraction branch includes an adaptive Chebyshev filter, a second differential amplifier circuit, and a second voltage follower; The output of the differential amplifier circuit and the precision resistor voltage divider circuit are connected to the input of the adaptive Chebyshev filter. The output of the adaptive Chebyshev filter is connected to the input of the second differential amplifier circuit; The output of the second differential amplifier circuit is connected to the input of the second voltage follower. The output of the second voltage follower is connected to the second analog-to-digital converter of the microcontroller; The adaptive Chebyshev filter extracts the DC data of the common-mode voltage. The DC data is amplified by the second differential amplifier circuit to the acquisition range of the second analog-to-digital converter. After passing through the second voltage follower, it is sampled by the second analog-to-digital converter to obtain the DC voltage component.

[0009] In some embodiments, the second differential amplifier circuit includes a second operational amplifier, a second input resistor, a second feedback resistor, a second grounding resistor, and a second output resistor; The output of the adaptive Chebyshev filter is connected to one end of the second input resistor, the other end of the second input resistor is connected to the inverting input of the second operational amplifier and the second ground resistor, and the other end of the second operational amplifier is connected to the second output resistor. The second feedback resistor is connected between the output terminal and the inverting input terminal of the second operational amplifier for negative feedback. The adaptive Chebyshev filter outputs DC data to the inverting input of the second operational amplifier; the second operational amplifier amplifies the DC data, and the second feedback resistor feeds the DC data back to the differential input of the second operational amplifier.

[0010] In some embodiments, the adaptive Chebyshev filter consists of an adjustable digital potentiometer, a low-temperature drift operational amplifier, a filter capacitor, a feedback capacitor, a fixed resistor, and a feedback resistor connected in a Sallen-Key topology to form a filter circuit. Among them, the adaptive Chebyshev filter is used to adapt to changes in parasitic parameters, enabling the filter circuit to have a steeper transition band, adjustable cutoff frequency, and adjustable ripple characteristics.

[0011] In some embodiments, a fixed resistor is connected to the differential input terminal of the low-temperature drift operational amplifier and one end of a filter capacitor, while the other end of the filter capacitor is grounded. One end of the adjustable digital potentiometer is connected to the output of the operational amplifier, and the other end is connected to the connection point between the fixed resistor and the differential input of the operational amplifier. A feedback resistor is connected between the inverting input and the output of the operational amplifier, and a feedback capacitor is connected between the inverting input and ground. The DC voltage passes through a fixed resistor, an adjustable digital potentiometer, and a filter capacitor in sequence before entering the differential input terminal of the operational amplifier. The operational amplifier amplifies the DC voltage to obtain the DC component, and the DC component is fed back to the inverting input terminal by the feedback resistor and feedback capacitor; An adjustable digital potentiometer is used to adaptively adjust the cutoff frequency of a filter circuit by changing its resistance value.

[0012] This invention proposes a common-mode voltage DC component extraction method based on an adaptive filter, which is applied to a common-mode voltage DC component extraction circuit based on an adaptive filter: A precision resistor voltage divider circuit divides the DC bus voltage, and a differential amplifier extracts the common-mode voltage from the divided DC bus voltage. The DC blocking circuit extracts the AC data from the common-mode voltage, and the AC data is amplified by the first differential amplifier circuit to obtain the AC voltage component; The DC extraction branch filters the common-mode voltage through an adaptive Chebyshev filter to obtain DC data, and then amplifies the DC data to obtain the DC voltage component. The frequency and amplitude are obtained by performing spectral analysis on the AC voltage components, which are then used to adjust the adaptive Chebyshev filter to convert the DC voltage components into digital signals.

[0013] In some embodiments, the process of obtaining frequency and amplitude based on the AC voltage component through spectral analysis to adjust the adaptive Chebyshev filter includes: When the frequency of the AC component data is affected by changes in parasitic parameters at the end of its life cycle, the microcontroller unit analyzes the lowest frequency and amplitude of the AC component using FFT. The resistance value of the adjustable digital potentiometer is adjusted according to the lowest frequency and amplitude of the AC component.

[0014] The DC voltage component is amplified by a programmable gain amplifier, and the gain error is compensated based on a preset calibration table to obtain the calibrated DC voltage component. The sampling rate of the second analog-to-digital converter is synchronized with the period of the spectral analysis of the AC voltage component; The calibrated DC voltage component is converted into a digital signal by a second analog-to-digital converter.

[0015] The present invention has at least the following beneficial technical effects: This invention proposes a common-mode voltage DC component extraction circuit and method based on an adaptive filter. The circuit includes a precision resistor voltage divider circuit, the input terminal of which is connected to the positive and negative terminals of the DC bus to obtain the common-mode voltage. AC acquisition branch, AC acquisition branch input terminal connected to the AC acquisition branch input terminal, used to acquire AC voltage components; The DC extraction branch has its input terminal connected to the second output terminal of the precision resistor voltage divider circuit, and is used to collect the DC voltage component. The microcontroller unit has its input terminals connected to the output terminals of the AC acquisition branch and the DC extraction branch. The output terminal of the microcontroller unit is connected to the input terminal of the DC extraction branch through a communication interface and is used to adjust the cutoff frequency of the adaptive filter.

[0016] This invention utilizes an adaptive filter-based common-mode voltage DC component extraction circuit. A precision resistor voltage divider circuit connects to the positive and negative terminals of the DC bus and samples the voltage for stable voltage division. The signal is transmitted to the AC acquisition branch and the DC extraction branch to collect AC and DC component data. The AC acquisition branch and the DC extraction branch work together, and combined with the dynamic parameter adjustment capability of the adaptive filter, effectively separate and suppress AC harmonics and interference components in the bus voltage, significantly improving the accuracy and anti-interference performance of DC component extraction. The AC and DC extraction branches output data to a microcontroller unit. The microcontroller unit adjusts the cutoff frequency of the adaptive filter in the DC extraction branch and performs insulation level prediction via the SPI (Serial Peripheral Interface) communication interface. Based on a closed-loop algorithm, the filtering parameters of the DC extraction branch are controlled, enabling the system to adapt to voltage fluctuations, load changes, and nonlinear interference. This achieves high accuracy, strong robustness, and real-time response characteristics in DC component extraction. This method can accurately process DC bus voltage signals, ensuring system stability and safety.

[0017] This invention can automatically adjust the filtering characteristics according to changes in parasitic parameters, ensuring accurate extraction of DC components under different operating conditions, making insulation detection and fault diagnosis results more reliable, adapting to various complex environments, reducing performance fluctuations caused by environmental changes, enhancing system stability, and reducing the risk of faults caused by system instability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0019] Figure 1 The circuit diagram for extracting the DC component of common-mode voltage based on an adaptive filter provided by this invention is shown.

[0020] Figure 2 A schematic diagram of the structure of an embodiment of the computer device provided by the present invention.

[0021] Figure 3 This is a schematic diagram of an embodiment of the computer-readable storage medium provided by the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0023] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0024] This invention proposes a common-mode voltage DC component extraction circuit based on an adaptive filter. Please refer to [link / reference]. Figure 1 ,include: A precision resistor voltage divider circuit, the input terminals of which are connected to the positive and negative terminals of the DC bus, is used to obtain the common-mode voltage; The AC acquisition branch has its input terminal connected to the first output terminal of the precision resistor voltage divider circuit, and is used to acquire AC voltage components. The DC extraction branch has its input terminal connected to the second output terminal of the precision resistor voltage divider circuit, and is used to collect the DC voltage component. The microcontroller unit has its input terminals connected to the output terminals of the AC acquisition branch and the DC extraction branch. The output terminal of the microcontroller unit is connected to the input terminal of the DC extraction branch through a communication interface and is used to adjust the cutoff frequency of the adaptive filter.

[0025] The precision resistor voltage divider circuit is directly connected to the positive and negative terminals of the DC bus, enabling direct acquisition of the bus voltage signal. It then converts the signal to a suitable voltage range through voltage division, ensuring stable and reliable signal acquisition. Its output is connected to the input of a differential amplifier, which effectively suppresses common-mode interference, enhances signal immunity, and improves signal quality. The two outputs of the differential amplifier are connected to the inputs of the AC acquisition branch and the DC extraction branch, respectively, achieving independent acquisition of AC and DC signals without interference, allowing for the simultaneous acquisition of two signals with different characteristics.

[0026] The output terminals of the AC and DC branches are connected to the input terminals of the microcontroller unit, enabling the microcontroller unit to fully receive, analyze, and judge the processed signals. The microcontroller unit connects to the input terminal of the DC extraction branch via an SPI communication interface, allowing for real-time dynamic adjustment of the cutoff frequency of the adaptive filter in the DC extraction branch. This enhances the circuit's adaptability to different operating conditions, improves overall performance and stability, and ensures efficient system operation.

[0027] The communication interface built into the digital potentiometer mentioned in this invention includes SPI, IIC and Up / Down & Increment type communication interfaces. The MCU can adjust or control the actual resistance value of the potentiometer through the interface without manual adjustment, which improves the adjustment accuracy and realizes precise dynamic adjustment of the resistance value.

[0028] Low-cost, low-power operational amplifiers with a wide operating temperature range include the LM358, LM2904DR, NE5532DR, and LM324 operational amplifiers; low power consumption extends battery life or reduces heat dissipation requirements, and the wide operating temperature range ensures stable operation under different environmental conditions, improving system reliability and adaptability.

[0029] High-precision, low-offset-voltage cryogenic operational amplifiers include the OP07, OPA182, OPA2182, and OPA4182 models. The low-temperature drift characteristic results in minimal output voltage variation at different temperatures, ensuring measurement accuracy. High precision captures minute signal changes, while low offset voltage reduces initial errors and improves measurement linearity.

[0030] Analog-to-digital converters with resolutions higher than 16 bits and sampling frequencies higher than 50 kHz include the ADS1115, ADS1110, AD7689, and MAX31865 models; high resolution improves measurement accuracy; high sampling frequency ensures accurate real-time capture of rapidly changing signals, avoiding signal distortion or omission.

[0031] In some embodiments, please refer to Figure 1 The AC acquisition branch includes a DC blocking circuit, a first differential amplifier circuit, and a first voltage follower. The output of the precision resistor voltage divider circuit is connected to the input of the DC blocking circuit; The output of the DC blocking circuit is connected to the input of the first differential amplifier circuit; The output of the first differential amplifier circuit is connected to the input of the first voltage follower; The output of the first voltage follower is connected to the first analog-to-digital converter of the microcontroller; The DC blocking circuit extracts the common-mode voltage to obtain AC data, which is then amplified by the first differential amplifier circuit to the acquisition range of the first analog-to-digital converter. After passing through the first voltage follower, the first analog-to-digital converter samples the AC voltage component.

[0032] The DC blocking circuit utilizes the characteristic of capacitors to block DC and pass AC, isolating the DC component in the common-mode voltage and allowing only the AC component to pass through, thus avoiding interference from DC signals and ensuring the accuracy of AC acquisition.

[0033] The output of the DC blocking circuit is connected to the input of the first differential amplifier circuit. The first differential amplifier circuit can amplify the AC component after it has been blocked by the capacitor to obtain AC component data, thereby enhancing the strength of the AC component data and improving its usability.

[0034] The output of the first differential amplifier circuit is connected to the input of the first voltage follower, which features high input impedance and low output impedance. The high input impedance reduces the load on the preceding circuitry, ensuring that the AC component data output from the first differential amplifier circuit remains unaffected. The low output impedance enhances the driving capability of the AC component data, enabling more stable transmission of the AC component data to the first analog-to-digital converter (ADC) of the microcontroller unit. Connecting the output of the first voltage follower to the first ADC achieves accurate conversion of the AC component data from analog to digital.

[0035] In some embodiments, please refer to Figure 1 The first differential amplifier circuit includes a first operational amplifier, a first input resistor, a second input resistor, a first feedback resistor, a first grounding resistor, and a first output resistor; The output terminal of the DC blocking circuit is connected to one end of the first input resistor, the other end of the first input resistor is connected to the inverting input terminal of the first operational amplifier and the first grounding resistor respectively, and the other end of the first operational amplifier is connected to the first output resistor; The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier for negative feedback. The DC blocking circuit transmits AC data to the inverting input of the first operational amplifier; the first operational amplifier amplifies the AC data; and the first feedback resistor feeds the AC data back to the differential input of the first operational amplifier.

[0036] The output of the DC blocking circuit is connected to one end of the first input resistor, and the other end of the first input resistor is connected to the differential input of the first operational amplifier, thus realizing the transmission of AC components and current limiting. The first input resistor can effectively limit the current flowing into the differential input of the first operational amplifier, preventing damage to the operational amplifier due to excessive current and ensuring the safety of the circuit.

[0037] The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier, forming a negative feedback structure. Negative feedback is a key factor in stabilizing the performance of the amplifier circuit, improving the stability of the first operational amplifier, and enabling it to maintain stable amplification and output characteristics even when faced with external interference such as temperature changes and power supply fluctuations.

[0038] In some embodiments, please refer to Figure 1 The DC extraction branch includes an adaptive Chebyshev filter, a second differential amplifier circuit, and a second voltage follower. The output of the precision resistor voltage divider circuit is connected to the input of the adaptive Chebyshev filter; The output of the adaptive Chebyshev filter is connected to the input of the second differential amplifier circuit; The output of the second differential amplifier circuit is connected to the input of the second voltage follower. The output of the second voltage follower is connected to the second analog-to-digital converter of the microcontroller; The adaptive Chebyshev filter extracts the DC data of the common-mode voltage. The DC data is amplified by the second differential amplifier circuit to the acquisition range of the second analog-to-digital converter. After passing through the second voltage follower, it is sampled by the second analog-to-digital converter to obtain the DC voltage component.

[0039] Within the acquisition range, the data is sampled by a second analog-to-digital converter after passing through a second voltage follower.

[0040] The output of the differential amplifier circuit is directly connected to the input of the adaptive Chebyshev filter. The Chebyshev filter itself has good frequency selectivity, and the adaptive filter can dynamically adjust its parameters according to the actual signal conditions to ensure that the signal output from the differential amplifier circuit can enter the filter as soon as possible, effectively and accurately filtering out AC components.

[0041] The output of the adaptive Chebyshev filter is connected to the input of the second differential amplifier circuit, which amplifies the relatively weak DC component after filtering. This amplifies the obtained DC component data, bringing it to a range suitable for acquisition by the microcontroller's second analog-to-digital converter, thus enhancing the strength and usability of the DC component data and obtaining more accurate data.

[0042] The output of the second differential amplifier circuit is connected to the input of the second voltage follower. The high input impedance and low output impedance of the second voltage follower reduce the load on the preceding amplifier circuit, ensuring stable transmission of DC component data and enhancing the driving capability of the DC component data. Its output is connected to the second analog-to-digital converter, enabling accurate conversion of the DC component data from analog to digital.

[0043] In some embodiments, please refer to Figure 1 The second differential amplifier circuit includes a second operational amplifier, a second input resistor, a second feedback resistor, a second grounding resistor, and a second output resistor. The output of the adaptive Chebyshev filter is connected to one end of the second input resistor, the other end of the second input resistor is connected to the inverting input of the second operational amplifier and the second ground resistor, and the other end of the second operational amplifier is connected to the second output resistor. The second feedback resistor is connected between the output terminal and the inverting input terminal of the second operational amplifier for negative feedback. The adaptive Chebyshev filter outputs DC data to the inverting input of the second operational amplifier; the second operational amplifier amplifies the DC data, and the second feedback resistor feeds the DC data back to the differential input of the second operational amplifier.

[0044] The output of the adaptive Chebyshev filter is connected to one end of the second input resistor, and the other end of the second input resistor is connected to the non-inverting input of the second operational amplifier, thus achieving the function of DC component buffering and adaptation. The second input resistor can effectively limit the current flowing into the non-inverting input of the second operational amplifier, preventing the operational amplifier from being overwhelmed by excessive current.

[0045] The second feedback resistor is connected between the output terminal and the inverting input terminal of the second operational amplifier, forming a negative feedback structure to meet the amplification requirements of different DC components. The DC component processed by the adaptive Chebyshev filter can be amplified to the range of the microcontroller unit.

[0046] In some embodiments, please refer to Figure 1 The adaptive Chebyshev filter consists of an adjustable digital potentiometer, a low-temperature drift operational amplifier, a filter capacitor, a feedback capacitor, a fixed resistor, and a feedback resistor connected in a Sallen-Key topology to form the filter circuit.

[0047] Among them, the adaptive Chebyshev filter is used to adapt to changes in parasitic parameters, enabling the filter circuit to have a steeper transition band, adjustable cutoff frequency, and adjustable ripple characteristics.

[0048] The Sallen-Key topology provides a stable and efficient framework for filters.

[0049] In some embodiments, please refer to Figure 1 A fixed resistor is connected to the non-inverting input of the low-temperature drift operational amplifier and one end of the filter capacitor, while the other end of the filter capacitor is grounded. One end of the adjustable digital potentiometer is connected to the output terminal of the operational amplifier, and the other end is connected to the connection point of the fixed resistor and the non-inverting input terminal of the operational amplifier. A feedback resistor is connected between the inverting input and the output of the operational amplifier, and a feedback capacitor is connected between the inverting input and ground.

[0050] The DC voltage passes through a fixed resistor, an adjustable digital potentiometer, and a filter capacitor in sequence before entering the non-inverting input of the operational amplifier. The operational amplifier amplifies the DC voltage to obtain the DC component, and the DC component is fed back to the inverting input terminal by the feedback resistor and feedback capacitor; An adjustable digital potentiometer is used to adaptively adjust the cutoff frequency of a filter circuit by changing its resistance value.

[0051] A fixed resistor is connected between the non-inverting input of the low-temperature drift operational amplifier and one end of a filter capacitor, with the other end of the filter capacitor grounded, forming a simple low-pass filter structure. The fixed resistor serves to limit current and divide voltage, while the filter capacitor effectively filters out high-frequency noise interference, making the signal entering the non-inverting input of the operational amplifier purer and more stable.

[0052] An adjustable digital potentiometer is connected at one end to the output of an operational amplifier and at the other end to the connection point of a fixed resistor and the non-inverting input, forming an adjustable negative feedback loop. By adjusting the resistance value of the digital potentiometer, the strength of the negative feedback can be flexibly changed, thereby dynamically adjusting the amplification factor of the operational amplifier.

[0053] A feedback resistor is connected between the inverting input and output of the operational amplifier, and a feedback capacitor is connected between the inverting input and ground. The feedback resistor and capacitor work together to stabilize the circuit's gain and frequency response, improve its phase characteristics, reduce distortion, and enable the operational amplifier to amplify the input signal more stably and accurately.

[0054] This invention proposes a method for extracting the DC component of common-mode voltage based on an adaptive filter. Please refer to [link to relevant documentation]. Figure 2 It is applied in a common-mode voltage DC component extraction circuit based on an adaptive filter: A precision resistor voltage divider circuit divides the DC bus voltage, and a differential amplifier extracts the common-mode voltage from the divided DC bus voltage. The DC blocking circuit extracts the AC data from the common-mode voltage, and the AC data is amplified by the first differential amplifier circuit to obtain the AC voltage component; The DC extraction branch filters the common-mode voltage through an adaptive Chebyshev filter to obtain DC data, and then amplifies the DC data to obtain the DC voltage component. The frequency and amplitude are obtained by performing spectral analysis on the AC voltage components, which are then used to adjust the adaptive Chebyshev filter to convert the DC voltage components into digital signals.

[0055] The DC bus voltage of the energy storage converter is divided by a precision resistor, and the common-mode voltage is extracted by a differential amplifier circuit with high input impedance. Then it is divided into two paths: an AC acquisition branch and a DC extraction branch.

[0056] The AC acquisition branch extracts the AC component through a DC blocking circuit, amplifies it to the optimal acquisition range of the ADC through a differential amplifier circuit, and then samples it through a high input impedance voltage follower before performing spectrum analysis using FFT. The DC extraction branch uses an adaptive Chebyshev filter with a Sallen-Key topology, consisting of adjustable digital potentiometers, low-temperature drift operational amplifiers, capacitors, resistors, and other components. This pre-amplified anti-aliasing allows the filter circuit to have a steeper transition band, adjustable cutoff frequency, and adjustable ripple characteristics to adapt to changes in parasitic parameters.

[0057] This invention achieves targeted suppression with attenuation exceeding 40dB, dynamically adapts to and automatically tracks changes in interference frequency, and consistently maintains optimal filtering performance. Adjustable ripple characteristics achieve an optimal balance between flatness and steepness for passband optimization, ensuring long-term stability. Regular self-calibration compensates for component aging, guaranteeing performance throughout its entire lifecycle.

[0058] In some embodiments, the process of obtaining frequency and amplitude based on the AC voltage component through spectral analysis to adjust the adaptive Chebyshev filter includes: When the frequency of the AC component data is affected by changes in parasitic parameters at the end of its life cycle, the microcontroller unit analyzes the lowest frequency and amplitude of the AC component using FFT. The resistance value of the adjustable digital potentiometer is adjusted according to the lowest frequency and amplitude of the AC component.

[0059] When the parasitic parameters on the DC side change due to factors such as temperature at the end of the life cycle, thus affecting the frequency of the AC component of the common-mode voltage, the MCU (Microcontroller Unit) analyzes the lowest frequency of the AC component through FFT (Fast Fourier Transform), adjusts the resistance of the adjustable digital potentiometer through SPI communication, and then adjusts the cutoff frequency of the adaptive filter. The DC component output by the filter is amplified by the differential amplifier circuit to the optimal acquisition range of the ADC (Analog-to-Digital Converter), and then sampled by the ADC after passing through a high input impedance voltage follower.

[0060] End-of-life refers to the degradation of system performance caused by equipment aging and component wear. Parasitic parameters are unexpected resistance, capacitance, inductance, and other parameters in a circuit. In signal processing, the AC component refers to the part of a signal that changes periodically over time, with frequency being a key characteristic. Parasitic resistance, capacitance, or inductance in a circuit introduces additional impedance, causing changes in the phase and amplitude of the signal transmission path. Parasitic capacitance creates a low-pass filtering effect, weakening high-frequency components; parasitic inductance induces resonance, altering the frequency response. Equipment aging causes component performance drift, such as a decrease in capacitance and an increase in resistance, which in turn changes the frequency characteristics of the signal. Wear on motor bearings introduces mechanical vibration, generating new frequency components or altering the frequency of existing AC components.

[0061] In some embodiments, the process of converting the DC voltage component into a digital signal includes: The DC voltage component is amplified by a programmable gain amplifier, and the gain error is compensated based on a preset calibration table to obtain the calibrated DC voltage component. The sampling rate of the second analog-to-digital converter is synchronized with the period of the spectral analysis of the AC voltage component; The calibrated DC voltage component is converted into a digital signal by a second analog-to-digital converter.

[0062] The DC voltage component is amplified in multiple stages by a programmable gain amplifier (PGA). The digital processing unit dynamically adjusts the gain coefficient of the PGA based on the real-time amplitude of the DC bus voltage to ensure that the output signal amplitude always matches the input range of the second analog-to-digital converter. A low-pass filter is connected in series at the PGA output, and its cutoff frequency is dynamically set by the digital processing unit based on the spectral analysis results of the AC voltage component to filter out residual high-frequency interference. The gain nonlinearity error of the PGA is compensated by a lookup table method, and the calibration table is pre-generated based on the gain-temperature characteristic curve measured during the production stage.

[0063] This invention achieves insulation level monitoring of the DC bus of the PCS (Power Conversion System) during dynamic charging and discharging through simple hardware and algorithms. It realizes DC insulation monitoring of the PCS throughout its entire operating cycle without affecting static insulation detection, thereby improving the safety and reliability of the energy storage system.

[0064] Based on the same inventive concept, according to another aspect of the present invention, such as Figure 2 As shown, an embodiment of the present invention also provides a computer device 30, which includes a processor 310 and a memory 320. The memory 320 stores a computer program 321 that can be run on the processor. When the processor 310 executes the program, it performs the steps of the method described above.

[0065] Based on the same inventive concept, according to another aspect of the present invention, such as Figure 3 As shown, embodiments of the present invention also provide a computer-readable storage medium 40, which stores a computer program 410 that, when executed by a processor, performs the methods described above.

[0066] Embodiments of the present invention may also include a corresponding computer device. The computer device includes a memory, at least one processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes any of the methods described above when executing the program.

[0067] The memory, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions / modules in the embodiments of this application. The processor executes various functional applications and data processing of the device by running the non-volatile software programs, instructions, and modules stored in the memory, thereby implementing the above-described method.

[0068] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the device. Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the local module via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0069] Finally, it should be noted that those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The storage medium for the program can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. The above computer program embodiments can achieve the same or similar effects as any of the corresponding foregoing method embodiments.

[0070] Those skilled in the art will also understand that the various exemplary logic blocks, modules, circuits, and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the functionality of various illustrative components, blocks, modules, circuits, and steps has been generally described. Whether this functionality is implemented as software or as hardware depends on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art can implement the functionality in various ways for each specific application, but such implementation decisions should not be construed as departing from the scope of the embodiments disclosed herein.

[0071] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. The sequence numbers of the disclosed embodiments of this invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0072] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0073] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A common-mode voltage DC component extraction circuit based on an adaptive filter, characterized in that, include: A precision resistor voltage divider circuit, wherein the input terminal of the precision resistor voltage divider circuit is connected to the positive and negative terminals of the DC bus to obtain the common-mode voltage; An AC acquisition branch, the input terminal of which is connected to the first output terminal of the precision resistor voltage divider circuit, is used to acquire AC voltage components; A DC extraction branch, the input terminal of which is connected to the second output terminal of the precision resistor voltage divider circuit, is used to collect DC voltage components; A microcontroller unit, the input of which is connected to the output of the AC acquisition branch and the output of the DC extraction branch, and the output of which is connected to the input of the DC extraction branch via a communication interface, is used to adjust the cutoff frequency of the adaptive filter.

2. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 1, characterized in that, The AC acquisition branch includes a DC blocking circuit, a first differential amplifier circuit, and a first voltage follower; The output terminal of the precision resistor voltage divider circuit is connected to the input terminal of the DC blocking circuit; The output terminal of the DC blocking circuit is connected to the input terminal of the first differential amplifier circuit; The output of the first differential amplifier circuit is connected to the input of the first voltage follower; The output of the first voltage follower is connected to the first analog-to-digital converter of the microcontroller; The DC blocking circuit extracts AC data by separating the common-mode voltage. This data is then amplified by the first differential amplifier circuit to the acquisition range of the first analog-to-digital converter (ADC). After passing through the first voltage follower, the ADC samples the AC voltage component.

3. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 2, characterized in that, The first differential amplifier circuit includes a first operational amplifier, a first input resistor, a second input resistor, a first feedback resistor, a first grounding resistor, and a first output resistor; The output terminal of the DC blocking circuit is connected to one end of the first input resistor, the other end of the first input resistor is connected to the inverting input terminal of the first operational amplifier and the first grounding resistor respectively, and the other end of the first operational amplifier is connected to the first output resistor; The first feedback resistor is connected between the output terminal and the inverting input terminal of the first operational amplifier for negative feedback. The DC blocking circuit transmits AC data to the inverting input of the first operational amplifier; the first operational amplifier amplifies the AC data; and the first feedback resistor feeds the AC data back to the differential input of the first operational amplifier.

4. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 1, characterized in that, The DC extraction branch includes an adaptive Chebyshev filter, a second differential amplifier circuit, and a second voltage follower; The output of the precision resistor voltage divider circuit is connected to the input of the adaptive Chebyshev filter; The output of the adaptive Chebyshev filter is connected to the input of the second differential amplifier circuit; The output of the second differential amplifier circuit is connected to the input of the second voltage follower. The output of the second voltage follower is connected to the second analog-to-digital converter of the microcontroller; The adaptive Chebyshev filter extracts the DC data of the common-mode voltage. The DC data is amplified by the second differential amplifier circuit to the acquisition range of the second analog-to-digital converter. After passing through the second voltage follower, it is sampled by the second analog-to-digital converter to obtain the DC voltage component.

5. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 4, characterized in that, The second differential amplifier circuit includes a second operational amplifier, a second input resistor, a second feedback resistor, a second grounding resistor, and a second output resistor; The output terminal of the adaptive Chebyshev filter is connected to one end of the second input resistor, the other end of the second input resistor is connected to the inverting input terminal of the second operational amplifier and the second ground resistor respectively, and the other end of the second operational amplifier is connected to the second output resistor; The second feedback resistor is connected between the output terminal and the inverting input terminal of the second operational amplifier for negative feedback; The adaptive Chebyshev filter outputs DC data to the inverting input of the second operational amplifier; the second operational amplifier amplifies the DC data, and the second feedback resistor feeds the DC data back to the differential input of the second operational amplifier.

6. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 5, characterized in that, The adaptive Chebyshev filter includes an adjustable digital potentiometer, a low-temperature drift operational amplifier, a filter capacitor, a feedback capacitor, a fixed resistor, and a feedback resistor, and is connected in a Sallen-Key topology to form a filter circuit. The adaptive Chebyshev filter is used to adapt to changes in parasitic parameters, enabling the filter circuit to have a steeper transition band, adjustable cutoff frequency, and adjustable ripple characteristics.

7. The common-mode voltage DC component extraction circuit based on an adaptive filter according to claim 6, characterized in that, The fixed resistor is connected to the non-inverting input of the low-temperature drift operational amplifier and one end of the filter capacitor, and the other end of the filter capacitor is grounded. One end of the adjustable digital potentiometer is connected to the output terminal of the operational amplifier, and the other end is connected to the connection point between the fixed resistor and the non-inverting input terminal of the operational amplifier. The feedback resistor is connected between the inverting input terminal and the output terminal of the operational amplifier, and the feedback capacitor is connected between the inverting input terminal and ground. The DC voltage passes sequentially through the fixed resistor, the adjustable digital potentiometer, and the filter capacitor before entering the non-inverting input of the operational amplifier. The operational amplifier amplifies the DC voltage to obtain a DC component, and the feedback resistor and the feedback capacitor feed the DC component back to the inverting input terminal. The adjustable digital potentiometer is used to adaptively adjust the cutoff frequency of the filter circuit by changing its resistance value.

8. A common-mode voltage DC component extraction method based on an adaptive filter, applied in any one of the common-mode voltage DC component extraction circuits based on an adaptive filter as described in claims 1-7, characterized in that: The precision resistor voltage divider circuit divides the DC bus voltage, and the differential amplifier extracts the common-mode voltage from the divided DC bus voltage. The DC blocking circuit extracts the AC data from the common-mode voltage, and the AC data is amplified by the first differential amplifier circuit to obtain the AC voltage component. The DC extraction branch filters the common-mode voltage through the adaptive Chebyshev filter to obtain the DC data, and then amplifies the DC data to obtain the DC voltage component. The frequency and amplitude are obtained by performing spectral analysis on the AC voltage component, which are then used to adjust the cutoff frequency of the adaptive Chebyshev filter and convert the DC voltage component into a digital signal.

9. The common-mode voltage DC component extraction method based on an adaptive filter according to claim 8, characterized in that, The process of obtaining the frequency and amplitude based on the AC voltage component through spectral analysis to adjust the adaptive Chebyshev filter includes: When the frequency of the AC component data is affected by changes in parasitic parameters at the end of its life cycle, the microcontroller unit analyzes the lowest frequency and amplitude of the AC component using FFT. The resistance value of the adjustable digital potentiometer is adjusted according to the lowest frequency and amplitude of the AC component.

10. The method for extracting the DC component of common-mode voltage based on an adaptive filter according to claim 8, characterized in that, The process of converting the DC voltage component into a digital signal includes: The DC voltage component is amplified by a programmable gain amplifier, and the gain error is compensated based on a preset calibration table to obtain the calibrated DC voltage component. The sampling rate of the second analog-to-digital converter is synchronized with the period of the spectral analysis of the AC voltage component; The calibrated DC voltage component is converted into a digital signal by a second analog-to-digital converter.

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