Low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method and system

Abstract

This invention discloses a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method and system. Addressing the core shortcomings of existing DBD parameter measurement technologies, such as complex hardware, significant safety hazards from high-voltage sampling, inherent errors introduced by measurement capacitors, and imprecise derivations of single-current sampling schemes, this invention employs a two-step method to achieve full parameter measurement using only single-channel current sampling: First, pre-calibration is performed under low-voltage, undischarged conditions to obtain the DBD series equivalent capacitance and the initial phase of the excitation voltage; then, the circuit current is sampled under normal discharge conditions, and the discharge / undischarge interval is accurately divided using the sliding window variance method. Based on the data from the undischarged interval, a complete excitation voltage waveform is fitted, and finally, all equivalent parameters, including dielectric capacitance, air gap capacitance, discharge sustaining voltage, and discharge power, are calculated. This invention eliminates the need for additional hardware such as high-voltage probes and measurement capacitors, enabling online measurement of equivalent parameters.

Description

Technical Field

[0001] This invention belongs to the field of dielectric barrier discharge (DBD) parameter measurement technology, and particularly relates to a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method and system. Background Technology

[0002] Dielectric barrier discharge (DBD) is a core technology for generating low-temperature plasma at ambient pressure, widely used in industrial fields such as ozone synthesis, material surface modification, waste gas treatment, and plasma excitation. The equivalent parameters of a DBD load (dielectric capacitance C) are... d Air gap capacitance C g Discharge sustaining voltage U z The measurement accuracy of DBD equipment is the core foundation for power supply design, operating condition optimization, and operational status monitoring. Its measurement accuracy directly determines the operating efficiency and reliability of DBD equipment.

[0003] Currently, the mainstream method for measuring DBD parameters in industry and academia is the Lissajous graphical method. This method requires simultaneous sampling of the high-voltage excitation voltage and loop charge signal at both ends of the DBD. Hardware-wise, it must be equipped with a high-voltage probe and a series measurement capacitor, which has three major drawbacks:

[0004] 1. High-voltage sampling poses significant safety hazards. High-voltage probes are costly and complex to install, making them unsuitable for long-term online installation in industrial settings.

[0005] 2. Series-connected measurement capacitors introduce inherent systematic errors, leading to overestimation of dielectric capacitance measurements and distortion of discharge sustaining voltage. Increasing the capacitance value of the measurement capacitor can reduce the error, but this introduces interference from lead inductance, creating a trade-off between accuracy and reliability.

[0006] 3. The hardware components are numerous, and there is significant interference from parasitic parameters. The measurement results are easily affected by the field environment, resulting in poor robustness.

[0007] Existing single-current sampling DBD parameter measurement schemes suffer from problems such as imprecise derivation and reliance on ideal assumptions: either they cannot decouple unknown excitation voltage waveforms, or they cannot accurately divide the discharge / non-discharge intervals, resulting in large measurement errors. They can only remain at the theoretical derivation stage and cannot be implemented in industrial scenarios. Summary of the Invention

[0008] To overcome the aforementioned deficiencies of the prior art, the present invention aims to provide a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method and system that features extremely simple hardware, no high-voltage safety risks, rigorous derivation without approximations, and high measurement accuracy. It can accurately measure all equivalent parameters of DBD by sampling only a single current channel, and can be directly integrated into the power control system of industrial DBD equipment to achieve online real-time measurement.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] A method for measuring the equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD, characterized by comprising the following steps:

[0011] S1 Low-voltage pre-calibration: Maintain the excitation power supply of the DBD load as a standard sinusoidal voltage with a fixed frequency f, reduce the peak excitation voltage to the DBD's undischarged state, sample the instantaneous current signal i0(t) of the sampling circuit, integrate the current signal to obtain the charge waveform q0(t), and obtain the series equivalent capacitance C of the DBD's undischarged stage through sinusoidal fitting. eq The initial phase φ of the excitation voltage u ;

[0012] S2 High-voltage operating current sampling: Keep the frequency f of the excitation power supply unchanged and the initial phase unchanged, increase the peak value of the excitation voltage to the normal discharge state of DBD, sample the instantaneous current signal i(t) of the circuit within a complete cycle, and use the integration rule that is completely consistent with step S1 to integrate i(t) to obtain the charge waveform q(t) of the complete cycle.

[0013] S3 Discharge and non-discharge interval identification: Through the sliding window variance detection algorithm, the current signal i(t) is analyzed point by point to accurately divide the non-discharge interval and discharge interval within the complete cycle;

[0014] S4 Full-cycle excitation voltage waveform fitting: Extract charge data in the undischarged region, and combine it with the pre-calibrated fixed frequency f and initial phase φ u With series equivalent capacitance C eq The excitation voltage waveform u(t) of the complete cycle under normal discharge conditions is obtained by fitting.

[0015] S5 DBD Full Equivalent Parameter Solution: Based on the fitted excitation voltage waveform u(t) and charge waveform q(t), combined with the DBD nonlinear clamping equivalent model, the dielectric capacitance C of the DBD load is calculated. d Air gap capacitance C g Discharge sustaining voltage U z With discharge power P.

[0016] Furthermore, in step S1, the criteria for determining the DBD's undischarged state throughout the entire process are: the current signal i0(t) is a smooth sine wave without spike pulses and has no discharge pulse characteristics; the frequency f of the excitation power supply is in the range of 50Hz~50kHz, which is the common sinusoidal excitation frequency for industrial DBD equipment.

[0017] Furthermore, in steps S1 and S2, the zero-crossing reset digital integration method is used to integrate the current signal. Specifically, within each excitation cycle, when the current signal crosses zero, the integrator output is reset to 0, and the formula for calculating the charge waveform is:

[0018]

[0019] in, To completely eliminate integral drift caused by DC bias in current sampling for the instantaneous current signal obtained by sampling.

[0020] Furthermore, in step S1, the specific process of sine fitting is as follows:

[0021] In the undischarged state, DBD is a purely capacitive load, satisfying... The charge waveform q0(t) and the excitation voltage u(t) are standard sine waves with the same frequency and phase; by performing a sine fit on q0(t) using the least squares method, we obtain:

[0022]

[0023] in Angular frequency, The peak value of the charge. The initial phase of the charge;

[0024] The pre-calibration output result is: series equivalent capacitance. ,in The peak value of the excitation voltage during the low-voltage pre-calibration stage; the initial phase of the excitation voltage. It is in phase with the initial phase of the charge.

[0025] Furthermore, in step S3, the time-domain fluctuation characteristics of the current signal are analyzed by the sliding window variance detection algorithm to accurately divide the undischarged interval and the discharge interval.

[0026] Furthermore, in step S4, the specific process of fitting the excitation voltage waveform is as follows:

[0027] Under normal discharge conditions, the undischarged region still strictly meets the requirements. Linear relationship; extract charge data in the undischarged region, combined with known angular frequency with initial phase The peak value of the charge waveform was obtained by fitting using the least squares method. This allows us to obtain the excitation voltage waveform for the complete cycle:

[0028] ,

[0029] in, This represents the peak excitation voltage under normal discharge conditions.

[0030] Furthermore, in step S5, the specific process of solving the DBD fully equivalent parameters is as follows:

[0031] S51 dielectric capacitor Solution: DBD satisfies the following conditions during the discharge phase. That is, the discharge phase and A linear relationship is observed; extraction of the discharge range and The data is used to perform a linear fit; the slope of the fitted line is the dielectric capacitance. The accurate value;

[0032] S52 air gap capacitor Solution: The series equivalent capacitance obtained from the pre-calibration By reverse calculation, the air gap capacitance can be obtained: ;

[0033] S53 Discharge sustaining voltage Solution: The intercept of the linear fit during the discharge phase is ,therefore:

[0034]

[0035] S54 Discharge Power P Calculation: The discharge power is calculated through full-cycle numerical integration, using the following formula:

[0036]

[0037] Furthermore, in steps S1 and S2, a non-inductive sampling resistor is connected in series in the DBD main circuit to complete the current signal sampling in conjunction with a high-speed ADC. The sampling frequency of the high-speed ADC is not less than 100 times the excitation frequency f, and the number of sampling bits is not less than 12 bits.

[0038] The present invention also provides a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement system for implementing the above measurement method, comprising a current sampling module, a main control module and a parameter output module connected in sequence;

[0039] The current sampling module includes a non-inductive sampling resistor and a high-speed ADC unit, which are connected in series in the DBD main circuit to synchronously sample the instantaneous current signal of the circuit and output a discrete current sequence.

[0040] The main control module has a built-in low-voltage pre-calibration unit, an integral operation unit, an interval identification unit, a voltage fitting unit, and a parameter calculation unit, which are used to complete the processing, pre-calibration, interval division, voltage fitting, and equivalent parameter calculation of the current signal.

[0041] The parameter output module is used to output the measurement results of the dielectric capacitance, air gap capacitance, discharge sustaining voltage and discharge power of the DBD load.

[0042] Furthermore, it also includes a DBD excitation power supply module, which is electrically connected to the main control module and is used to output a standard sinusoidal high voltage with a fixed frequency and adjustable peak value. It can also receive instructions from the main control module to switch between low-voltage pre-calibration and high-voltage discharge conditions.

[0043] Beneficial effects

[0044] Compared with the prior art, the present invention has the following significant advantages:

[0045] 1. Extremely simple hardware, completely eliminating high voltage safety risks: This invention only requires a non-inductive sampling resistor connected in series in the DBD main circuit. All equivalent parameters can be measured by single-channel current sampling. No additional hardware such as high voltage probes and measuring capacitors is required. It can be directly installed on the grounding side of industrial DBD equipment.

[0046] 2. This invention is based on the DBD general nonlinear clamping equivalent model, which has a clear physical meaning; at the same time, it completely eliminates the series measurement capacitor, thus eliminating the inherent error introduced by the measurement capacitor from the root.

[0047] 3. It has wide adaptability and can realize online real-time measurement. Attached Figure Description

[0048] Figure 1 : Overall flowchart of the DBD equivalent parameter measurement method described in this invention;

[0049] Figure 2 : Current and charge waveforms during the low-voltage pre-calibration phase;

[0050] Figure 3 : Measured current waveform under normal discharge conditions;

[0051] Figure 4 : A marker sequence diagram for identifying the discharge / non-discharge region;

[0052] Figure 5 Based on the reconstruction of the DBD Lissajous figure in this invention; Detailed Implementation

[0053] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0054] like Figure 1As shown, this embodiment discloses a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement method for industrial DBD ozone generators, whose excitation power supply is a 10kHz high-frequency sinusoidal high-voltage generator with a rated output voltage peak value adjustable from 0 to 20kV. The specific implementation steps are as follows:

[0055] S1 Low-voltage pre-calibration

[0056] Keep the excitation power supply frequency fixed at 10kHz, reduce the peak excitation voltage to 2kV, so that the DBD load is in an undischarged state throughout the entire process. At this time, the current is a smooth sine wave without spikes.

[0057] A 10Ω / 5W high-precision non-inductive sampling resistor is connected in series in the main circuit on the ground side of the DBD. A high-speed ADC with a 12-bit sampling frequency of 1MSPS is used to synchronously sample the circuit current to obtain the discrete current sequence i0[n].

[0058] The current sequence is integrated using a zero-crossing reset digital integration method: within each excitation cycle (100μs), the integrator output is reset to 0 when the current crosses zero, resulting in the charge waveform q0(t), as shown in the figure. Figure 2 As shown, the charge waveform is a standard sine wave with the same frequency and phase as the excitation voltage.

[0059] By performing a sine fit on q0(t) using the least squares method, we obtain:

[0060]

[0061] Among them, the charge peak Initial phase of charge Low-voltage pre-calibrated excitation voltage peak value Therefore, the series equivalent capacitance is:

[0062] Initial phase of constant excitation voltage Complete the pre-calibration.

[0063] S2 High-voltage operating current sampling

[0064] Maintain the excitation power supply frequency at 10kHz and initial phase. Without changing the voltage, the peak excitation voltage was increased to 15kV to bring the DBD into normal discharge mode. Using the same sampling parameters as the pre-calibration, the loop current signal i(t) for one complete cycle was sampled. The measured current waveform is as follows. Figure 3 As shown, a large number of dense discharge pulse spikes appear near the voltage peak, while the area near the voltage zero-crossing point is a smooth, undischarged segment. Using the zero-crossing reset integration rule that is completely consistent with the pre-calibration, the charge waveform q(t) of the complete cycle is obtained by integrating i(t).

[0065] S3 Discharge and Non-Discharge Zone Identification

[0066] The time-domain fluctuation characteristics of the current signal are analyzed using a sliding window variance detection algorithm to accurately divide the undischarged and discharged intervals within a complete cycle. The resulting labeled sequence is as follows: Figure 4 As shown, two undischarged intervals and two discharge intervals are precisely divided, which perfectly match the characteristics of the current waveform.

[0067] S4 Full-cycle excitation voltage waveform fitting

[0068] Extract charge data from the undischarged region and combine it with the known angular frequency. Initial phase The peak value of the charge waveform was obtained by fitting using the least squares method. Thus, the peak excitation voltage is obtained: The final fitting yields the excitation voltage waveform for the complete cycle:

[0069]

[0070] S5 DBD Fully Equivalent Parameter Solution

[0071] Based on the fitted (u(t)) and (q(t)), all parameters are solved using the DBD nonlinear clamping equivalent model:

[0072] 1. Dielectric capacitance C d Solution: Extract the u(t) and q(t) data within the discharge range, perform linear fitting, and obtain the slope of the fitted line as follows: Therefore, dielectric capacitance ;

[0073] 2. Air gap capacitance C g Solution: Based on pre-calibration (C_{eq}=600\text{pF}), by reverse deduction we get:

[0074]

[0075] 3. Discharge sustaining voltage U z Solution: The intercept of the linear fit during the discharge phase is ,therefore:

[0076] .

[0077] 4. Discharge power calculation: The discharge power is calculated through full-cycle numerical integration. .

[0078] Based on the fitted u(t) and q(t), the reconstructed Lissajous figure is as follows: Figure 5As shown, it is a standard parallelogram, which is completely consistent with the measured figure of the traditional Lissajous method, verifying the accuracy of the measurement results of the present invention.

[0079] This embodiment also discloses a low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement system for implementing the above measurement method, including a DBD excitation power supply module, a current sampling module, a main control module, a parameter output module, and a fault early warning module connected in sequence.

[0080] The current sampling module includes a 10Ω non-inductive sampling resistor and a 12-bit high-speed ADC unit, which are connected in series in the main circuit on the ground side of the DBD load to synchronously sample the circuit current.

[0081] The main control module uses an STM32F4 series MCU, which has a built-in low-voltage pre-calibration unit, integration unit, interval identification unit, voltage fitting unit and parameter calculation unit, and can complete real-time processing and parameter calculation of current signals.

[0082] The parameter output module uses an OLED display to output the equivalent parameter measurement results of DBD in real time; the fault early warning module is electrically connected to the main control module and can determine the DBD operating status based on the measured equivalent parameters, triggering early warnings under operating conditions such as media aging and air gap abnormalities.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD, characterized in that, Includes the following steps: S1 Low-voltage pre-calibration: Keep the excitation power supply of the DBD load at a fixed frequency. f The standard sinusoidal voltage reduces the peak excitation voltage to a state where the DBD is not discharged throughout the entire process, and the instantaneous current signal of the sampling circuit is used. i 0( t The charge waveform is obtained by integrating the current signal. q 0( t The series equivalent capacitance of the DBD in the undischarged stage is obtained by sinusoidal fitting. C eq Initial phase with excitation voltage φ u ; S2 High-voltage operating current sampling: Maintaining the frequency of the excitation power supply f With the initial phase unchanged, the peak excitation voltage is increased to the normal discharge state of the DBD, and the instantaneous current signal of the circuit within one complete cycle is sampled. i ( t Using the same integration rules as in step S1, for i ( t Integrating yields the charge waveform for the complete cycle. q ( t ); S3 Discharge and Non-Discharge Zone Identification: This is achieved through a sliding window variance detection algorithm on the current signal. i ( t ) Perform point-by-point analysis to accurately divide the non-discharge interval and discharge interval within the complete cycle; S4 Full-cycle excitation voltage waveform fitting: Extract charge data in the undischarged region and combine it with a pre-calibrated fixed frequency. f Initial phase φ u series equivalent capacitance C eq The excitation voltage waveform of the complete cycle under normal discharge conditions was obtained by fitting. u (t); S5 DBD Full Equivalent Parameter Calculation: Based on the Fitted Excitation Voltage Waveform u (t), charge waveform q ( t By combining the DBD nonlinear clamping equivalent model, the dielectric capacitance of the DBD load is calculated. C d Air gap capacitance C g Discharge sustaining voltage U z With discharge power P .

2. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In step S1, the criterion for determining the DBD's undischarged state throughout the entire process is: current signal. i 0( t It is a smooth sine wave without spikes and without discharge pulse characteristics; frequency of excitation power supply f The range is 50Hz~50kHz, which is the common sinusoidal excitation frequency for industrial DBD equipment.

3. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In steps S1 and S2, the zero-crossing reset digital integration method is used to integrate the current signal. Specifically, within each excitation cycle, when the current signal crosses zero, the integrator output is reset to 0, and the formula for calculating the charge waveform is: ,in, To completely eliminate integral drift caused by DC bias in current sampling for the instantaneous current signal obtained by sampling.

4. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In step S1, the specific process of sinusoidal fitting is as follows: In the undischarged state, DBD is a purely capacitive load, satisfying... Charge waveform q 0 ( t ) and excitation voltage u (t) represents a standard sine wave of the same frequency and phase; the least squares method is used to... q 0 ( t By performing a sine fit, we obtain: .in Angular frequency, The peak value of the charge. The initial phase of the charge; the pre-calibrated output result is: series equivalent capacitance. ,in The peak value of the excitation voltage during the low-voltage pre-calibration stage; the initial phase of the excitation voltage. It is in phase with the initial phase of the charge.

5. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In step S3, the time-domain fluctuation characteristics of the current signal are analyzed by the sliding window variance detection algorithm to accurately divide the undischarged interval and the discharge interval.

6. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In step S4, the specific process of fitting the excitation voltage waveform is as follows: Under normal discharge conditions, the undischarged region still strictly satisfies Linear relationship; extract charge data in the undischarged region, combined with known angular frequency with initial phase The peak value of the charge waveform was obtained by fitting using the least squares method. This allows us to obtain the excitation voltage waveform for the complete cycle: , ,in, This represents the peak excitation voltage under normal discharge conditions.

7. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In step S5, the specific process of solving the DBD fully equivalent parameters is as follows: S51 Dielectric capacitance Solution: DBD satisfies the following conditions during the discharge phase. That is, the discharge phase and A linear relationship is observed; extraction of the discharge range and The data is used to perform a linear fit; the slope of the fitted line is the dielectric capacitance. The accurate value; S52 air gap capacitor Solution: The series equivalent capacitance obtained from the pre-calibration By reverse calculation, the air gap capacitance can be obtained: S53 Discharge sustaining voltage Solution: The intercept of the linear fit during the discharge phase is ,therefore: S54 discharge power P Solution: The discharge power is calculated through full-cycle numerical integration, using the following formula: .

8. The method for measuring equivalent parameters of a low-voltage pre-calibrated single-current sampling DBD according to claim 1, characterized in that, In steps S1 and S2, a non-inductive sampling resistor is connected in series in the DBD main circuit to complete the current signal sampling in conjunction with the high-speed ADC. The sampling frequency of the high-speed ADC is not lower than the excitation frequency. f 100 times that of the standard, with a sampling bit depth of no less than 12 bits.

9. A low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement system, characterized in that, The method for implementing the measurement method according to any one of claims 1-8 includes a current sampling module, a main control module, and a parameter output module connected in sequence. The current sampling module includes a non-inductive sampling resistor and a high-speed ADC unit, which are connected in series in the DBD main circuit to synchronously sample the instantaneous current signal of the circuit and output a discrete current sequence. The main control module has a built-in low-voltage pre-calibration unit, an integration unit, an interval identification unit, a voltage fitting unit, and a parameter calculation unit, which are used to complete the processing, pre-calibration, interval division, voltage fitting, and equivalent parameter calculation of the current signal. The parameter output module is used to output the measurement results of the dielectric capacitance, air gap capacitance, discharge sustaining voltage, and discharge power of the DBD load.

10. The low-voltage pre-calibrated single-current sampling DBD equivalent parameter measurement system according to claim 9, characterized in that, It also includes a DBD excitation power supply module, which is electrically connected to the main control module and is used to output a standard sinusoidal high voltage with a fixed frequency and adjustable peak value. It can also receive instructions from the main control module to switch between low-voltage pre-calibration and high-voltage discharge conditions.

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