CN-122017330-A - Common-mode voltage direct current component extraction circuit and method based on adaptive filter

CN122017330ACN 122017330 ACN122017330 ACN 122017330ACN-122017330-A

Abstract

The invention relates to the field of sampling circuits, and provides a common-mode voltage direct current component extraction circuit and a method based on an adaptive filter, wherein the method comprises the following steps: the input end of the precise resistor voltage dividing circuit is connected with the positive electrode and the negative electrode of the direct current bus and used for obtaining common mode voltage; the device comprises an alternating current acquisition branch, a direct current extraction branch, a micro control unit and a micro control unit, wherein the input end of the alternating current acquisition branch is connected with the first output end of the precision resistor voltage dividing circuit and used for acquiring alternating current voltage components, the input end of the direct current extraction branch is connected with the second output end of the precision resistor voltage dividing circuit and used for acquiring direct current voltage components, 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, and 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 used for adjusting the cut-off frequency of the self-adaptive filter.

Inventors

YANG HAIBO
CHEN XINGUANG
PAN JIANPING

Assignees

宁波德业储能科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260331

Claims (10)

1. The common-mode voltage direct current component extraction circuit based on the adaptive filter is characterized by comprising the following components: the input end of the precise resistor voltage dividing circuit is connected with the positive electrode and the negative electrode of the direct current bus and used for obtaining a common mode voltage; The input end of the alternating current acquisition branch is connected with the first output end of the precision resistor voltage dividing circuit and is used for acquiring alternating current voltage components; The input end of the direct current extraction branch is connected with the second output end of the precision resistor voltage dividing circuit and is used for collecting direct current voltage components; 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, and 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 used for adjusting the cut-off frequency of the self-adaptive filter.
2. The adaptive filter-based common-mode voltage direct current component extraction circuit of claim 1, wherein the alternating current acquisition branch comprises a direct current blocking circuit, a first differential amplification circuit and a first voltage follower; the output end of the precise resistor voltage dividing circuit is connected with the input end of the blocking circuit; The output end of the blocking circuit is connected to the input end of the first differential amplifying circuit; The output end of the first differential amplifying circuit is connected to the input end of the first voltage follower; the output of the first voltage follower is connected to a first analog-to-digital converter of the micro control unit; The DC blocking circuit extracts and separates common-mode voltage to obtain alternating-current data, the alternating-current data is amplified to be within the acquisition range of the first analog-to-digital converter through the first differential amplifying circuit, and then the alternating-current data is sampled by the first analog-to-digital converter after passing through the first voltage follower to obtain alternating-current voltage components.
3. The adaptive filter-based common-mode voltage direct current component extraction circuit according to claim 2, wherein the first differential amplification circuit comprises a first operational amplifier, a first input resistor, a second input resistor, a first feedback resistor, a first ground resistor, and a first output resistor; The output end of the blocking circuit is connected with one end of the first input resistor, the other end of the first input resistor is respectively connected with the inverting input end of the first operational amplifier and the first grounding resistor, and the other end of the first operational amplifier is connected with the first output resistor; the first feedback resistor is connected between the output end and the inverting input end of the first operational amplifier and used for negative feedback; the direct current blocking circuit is used for transmitting alternating current data to an inverting input end of the first operational amplifier, the first operational amplifier is used for amplifying the alternating current data, and the first feedback resistor is used for feeding the alternating current data back to a differential input end of the first operational amplifier.
4. The adaptive filter-based common-mode voltage direct current component extraction circuit of claim 1, wherein the direct current extraction branch comprises an adaptive chebyshev filter, a second differential amplification circuit, and a second voltage follower; the output end of the precise resistor divider circuit is connected to the input end of the self-adaptive chebyshev filter; the output end of the self-adaptive chebyshev filter is connected to the input end of the second differential amplifying circuit; the output end of the second differential amplifying circuit is connected to the input end of the second voltage follower; The output of the second voltage follower is connected to a second analog-to-digital converter of the micro control unit; the self-adaptive chebyshev filter extracts direct current data of a common-mode voltage, the direct current data is amplified to be in a collection range of the second analog-to-digital converter through the second differential amplifying circuit, and the direct current data is sampled by the second analog-to-digital converter after passing through the second voltage follower, so that a direct current voltage component is obtained.
5. The adaptive filter-based common-mode voltage direct current component extraction circuit of claim 4, wherein the second differential amplification circuit comprises a second operational amplifier, a second input resistor, a second feedback resistor, a second ground resistor, and a second output resistor; The output end of the self-adaptive chebyshev filter is connected with one end of the second input resistor, the other end of the second input resistor is respectively connected with the inverting input end of the second operational amplifier and the second grounding resistor, and the other end of the second operational amplifier is connected with the second output resistor; the second feedback resistor is connected between the output end and the inverting input end of the second operational amplifier and used for negative feedback; The self-adaptive Chebyshev filter outputs direct current data to an inverting input end of the second operational amplifier, the second operational amplifier amplifies the direct current data, and the second feedback resistor feeds the direct current data back to a differential input end of the second operational amplifier.
6. The self-adaptive filter-based common-mode voltage direct current component extraction circuit according to claim 5, wherein the self-adaptive chebyshev filter comprises 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 into the filter circuit according to a Sallen-Key topological structure; The self-adaptive chebyshev filter is used for adapting to parasitic parameter changes, so that the filter circuit has steeper transition zone, adjustable cut-off frequency and adjustable ripple characteristics.
7. The adaptive filter-based common-mode voltage DC component extraction circuit of claim 6, wherein, The fixed resistor is connected to the non-inverting input end 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 with the output end of the operational amplifier, and the other end of the adjustable digital potentiometer is connected with a connection point between the fixed resistor and the non-inverting input end of the operational amplifier; The feedback resistor is connected between the inverting input end and the output end of the operational amplifier, and the feedback capacitor is connected between the inverting input end and the ground; the direct-current voltage sequentially passes through the fixed resistor, the adjustable digital potentiometer and the filter capacitor and then enters the non-inverting input end of the operational amplifier; the operational amplifier amplifies the direct-current voltage to obtain a direct-current component, and the feedback resistor and the feedback capacitor feed back the direct-current component to the inverting input end; The adjustable digital potentiometer is used for adaptively adjusting the cut-off frequency of the filter circuit by changing the resistance value.
8. The method for extracting the common-mode voltage direct current component based on the adaptive filter is applied to the common-mode voltage direct current component extracting circuit based on the adaptive filter according to any one of claims 1 to 7, and is characterized in that: The precision resistor voltage dividing circuit divides the direct current bus voltage, and the differential amplifier extracts common mode voltage in the divided direct current bus voltage; the DC blocking circuit extracts alternating current data in the common mode voltage, and the alternating current data is amplified by the first differential amplifying circuit to obtain the alternating current voltage component; the direct current extraction branch circuit carries out filtering treatment on the common mode voltage through the self-adaptive chebyshev filter to obtain direct current data, and the direct current data is amplified to obtain the direct current voltage component; And carrying out frequency spectrum analysis according to the alternating voltage component to obtain frequency and amplitude for adjusting the cut-off frequency of the self-adaptive chebyshev filter, and converting the direct voltage component into a digital signal.
9. The method for extracting a dc component from a common-mode voltage based on an adaptive filter according to claim 8, wherein the step of performing a spectrum analysis on the ac component to obtain a frequency and an amplitude for adjusting the adaptive chebyshev filter comprises: The microcontroller unit analyzes the lowest frequency and amplitude of the alternating current component through FFT when the end of life or the change of parasitic parameters affects the frequency of the alternating current component data; And adjusting the resistance value of the adjustable digital potentiometer according to the lowest frequency and amplitude of the alternating current component.
10. The adaptive filter-based common-mode voltage direct current component extraction method according to claim 8, wherein the process of converting the direct current voltage component into a digital signal comprises: gain is carried out on the direct-current voltage component through a programmable gain amplifier, gain errors are compensated based on a preset calibration table, and a calibrated direct-current voltage component is obtained; Synchronizing the sampling rate of the second analog-to-digital converter with the period of the spectral analysis of the alternating voltage component; The calibrated direct voltage component is converted to a digital signal by the second analog-to-digital converter.

Description

Common-mode voltage direct current component extraction circuit and method based on adaptive filter Technical Field The invention relates to the field of sampling circuits, in particular to a common-mode voltage direct current component extraction circuit and a common-mode voltage direct current component extraction method based on an adaptive filter. Background In a power electronic system, monitoring of the voltage state of a direct current bus of equipment such as an energy storage converter is important. The common-mode voltage is taken as a key parameter in the direct-current bus voltage, and the accurate extraction of the direct-current component is important for the insulation detection of the system. The conventional common-mode voltage dc component extraction method mostly adopts a filter with fixed parameters, such as an RC (Resistor-Capacitor) low-pass filter. However, in practical applications, the working environment of the power electronic system is complex and variable, and factors such as temperature variation and equipment aging can cause parasitic parameters on the dc side to change. When the parasitic parameters are changed, the characteristics of the filter such as cut-off frequency and the like are not matched with the actual signals, and the alternating current component cannot be effectively filtered, so that the extracted direct current component contains larger errors, and the accuracy of operations such as insulation level prediction and the like is affected. Meanwhile, the traditional method lacks self-adaptive adjustment capability when dealing with complex and changeable signal frequency components, and can not accurately extract direct current components of common-mode voltage under different working conditions. Disclosure of Invention In order to solve the problems, the invention provides a common-mode voltage direct-current component extraction circuit and a method based on an adaptive filter, which can accurately extract the direct-current component of the common-mode voltage under different working conditions. Based on the above object, the present invention provides a common-mode voltage direct current component extraction circuit based on an adaptive filter, comprising: The input end of the precise resistor voltage dividing circuit is connected with the positive electrode and the negative electrode of the direct current bus and used for obtaining common mode voltage; The input end of the alternating current acquisition branch is connected with the first output end of the precision resistor divider circuit and is used for acquiring alternating current voltage components; the input end of the direct current extraction branch is connected with the second output end of the precision resistor voltage dividing circuit and is used for collecting direct current voltage components; 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, and 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 is used for adjusting the cut-off frequency of the self-adaptive filter. In some embodiments, the ac acquisition branch includes a dc blocking circuit, a first differential amplifying circuit, and a first voltage follower; the output end of the precise resistor voltage dividing circuit is connected with the input end of the blocking circuit; The output end of the blocking circuit is connected to the input end of the first differential amplifying circuit; The output end of the first differential amplifying circuit is connected to the input end of the first voltage follower; the output of the first voltage follower is connected to a first analog-to-digital converter of the micro control unit; The DC blocking circuit extracts and separates the common-mode voltage to obtain alternating-current data, the alternating-current data is amplified to be within the acquisition range of the first analog-to-digital converter through the first differential amplifying circuit, and then the alternating-current data is sampled by the first analog-to-digital converter after passing through the first voltage follower to obtain an alternating-current voltage component. In some embodiments, the first differential amplification circuit includes a first operational amplifier, a first input resistor, a second input resistor, a first feedback resistor, a first ground resistor, and a first output resistor; The output end of the blocking circuit is connected with one end of a first input resistor, the other end of the first input resistor is respectively connected with the inverting input end of the first operational amplifier and the first grounding resistor, and the other end of the first operational amplifier is connected with the first output resistor; the first feedback resistor is connected betwee