Design and optimization method and system for anti-interference common-mode filter of infrared sensor

Abstract

The invention discloses a method and a system for designing and optimizing an anti-interference common-mode filter of an infrared sensor. The method comprises the steps of winding a Rogowski coil, calculating a relation between output voltage and a current change rate, and calculating parameters of the Rogowski coil. Calculating the relation between the integrating circuit output voltage and the common-mode current, and setting integrating circuit parameters. And setting in-phase amplifier parameters to obtain a common-mode transformer circuit transfer function. Common-mode transformer circuit parameters are designed, and the winding turn ratio is calculated. According to the infrared sensor anti-interference common-mode filter design and optimization method and system provided by the invention, by optimizing the Rogowski coil and the integral circuit design, external common-mode interference signals are effectively filtered out, and accurate transmission of the signals is ensured. A parameterization design method is adopted, the circuit design and adjustment process is simplified, and scientific researchers can conduct experiments and optimization more conveniently. By optimizing the high-frequency band design, the resonance phenomenon is avoided, the measurement bandwidth of the Rogowski coil is remarkably expanded, and the application range of the system is widened.

Description

Technical Field

[0001] The present invention relates to the field of infrared sensor image transmission technology, and in particular to a design and optimization method and system for an infrared sensor anti-interference common mode filter. Background Art

[0002] Infrared light has the advantages of strong anti-interference ability, strong penetration ability, all-weather operation, and long effective use distance. Compared with visible light, it is more suitable for use in complex environments. Based on the above advantages, infrared imaging is widely used in security, satellite remote sensing, material testing, medicine, agriculture, military and other fields. With the advancement of science and technology, although infrared imaging technology is becoming more and more advanced, it still has shortcomings. The infrared sensor, the core component of the infrared imaging system, will inevitably introduce interference signals in the process of collecting image signals. This interference signal will be transmitted in the same direction along multiple lines at the output end of the sensor image signal, that is, the common mode interference signal. After the common mode interference signal is converted into a digital signal, the converted data bit is offset, and the bit originally 1 becomes 0, or the bit originally 0 becomes 1, thereby transmitting the dislocated RGB data to the main control chip for processing, causing the display terminal to have a flowery screen or a green screen.

[0003] For common-mode interference signals, they are usually sampled first, amplified by the amplifier circuit, and then injected into the interference source with a signal of the same amplitude and opposite phase as the interference signal to eliminate the common-mode interference. For interference signal sampling, Rogowski coils are often used in field testing due to their simple structure, no magnetic saturation problems, wide bandwidth, and protection of sensors; analog filters are composed of components such as resistors, inductors, capacitors, and op amps, and have the advantages of fast response speed, simple implementation, and convenient processing of continuous signals. Therefore, for signal amplification and reverse injection, analog filters are often used to amplify and compensate for interference signals. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by the present invention is that the existing infrared sensors are easily affected by external common-mode interference signals during signal transmission, resulting in reduced signal quality and increased errors. Specific problems include poor anti-interference ability, infrared sensors are easily affected by external electromagnetic interference, affecting the accuracy of signal transmission; complex design, the existing anti-interference circuit design is complex, and parameter adjustment is difficult, affecting circuit optimization and performance improvement; frequency band limitation, traditional filters are prone to resonance in the high frequency band, limiting their measurement bandwidth.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a design and optimization method of an infrared sensor anti-interference common mode filter, comprising: winding a Rogowski coil, calculating the relationship between the output voltage and the current change rate, and calculating the Rogowski coil parameters.

[0007] Calculate the relationship between the output voltage and common-mode current of the integration circuit and set the integration circuit parameters.

[0008] Set the parameters of the common-mode amplifier and obtain the transfer function of the common-mode transformer circuit.

[0009] Design the common-mode transformer circuit parameters and calculate the winding turns ratio.

[0010] 2 As a preferred solution of the design and optimization method of the infrared sensor anti-interference common mode filter of the present invention, wherein: the winding of the Rogowski coil and the calculation of the relationship between the output voltage and the current change rate include: the Rogowski coil is made of a wire evenly and symmetrically wound on a non-ferromagnetic material, and the primary side conductor vertically passes through the center of the skeleton. When a changing current flows through the conductor, a changing magnetic field is generated around the conductor, and the output voltage v(t) is proportional to the change rate of the current to be measured, which is expressed as:

[0011]

[0012] Among them, cm (t) / dt represents the rate of change of the current to be measured, a represents the inner diameter of the coil, b represents the outer diameter of the coil, h represents the height of the coil, N represents the number of turns of the coil, φ represents the magnetic flux, μ0 represents the magnetic permeability of vacuum, and M represents the mutual inductance between the coil and the conductor to be measured.

[0013] 3 As a preferred solution of the infrared sensor anti-interference common mode filter design and optimization method described in the present invention, wherein: the calculation of the Rogowski coil parameters includes directly measuring the inner diameter, outer diameter and height of the coil, and the number of turns N of the coil is expressed as:

[0014]

[0015] Wherein, p represents the wire diameter of the copper wire.

[0016] The first resonance point fl is used as the upper limit of the measurement bandwidth of the Rogowski coil. fl is calculated from the internal parasitic parameters of the Rogowski coil. In order to maintain a certain margin, the relationship between the first resonance point fl and the upper limit of the noise frequency band fhigh is expressed as:

[0017] f l ≥10f high

[0018] The first resonance point f l than the upper limit of the noise frequency band f high 10 times higher.

[0019] As a preferred solution of the infrared sensor anti-interference common mode filter design and optimization method described in the present invention, the calculation of the relationship between the output voltage and the common mode current of the integration circuit includes that, for the integration circuit, the voltage and the integrated common mode current are proportional, and the proportional coefficient K is determined by the integration circuit structure. The relationship between the output voltage and the common mode current of the integration circuit is expressed as:

[0020]

[0021] Among them, μ o represents the output voltage of the integration circuit, R1 represents the resistance value, C1 represents the capacitance value, K represents the proportional coefficient, and t represents the time.

[0022] 5 As a preferred solution of the infrared sensor anti-interference common mode filter design and optimization method described in the present invention, wherein: the setting of the integral circuit parameters includes directly measuring the value of the resistor R1 and setting the value of C1 according to the unit gain frequency ft1. The resistor R2 determines the lower limit cutoff frequency f of the Rogowski coil sensor. a , f a The minimum noise frequency f low Ten times smaller.

[0023] To prevent the operational amplifier from saturating, make the unity gain frequency more than 10 times greater than the highest noise frequency that needs to be filtered. All parameters are expressed as:

[0024]

[0025] Among them, f t1 represents the unity gain frequency, f a Represents the lower cutoff frequency, f low Indicates the minimum noise frequency band, f high Indicates the highest noise frequency.

[0026] 6 As a preferred solution of the infrared sensor anti-interference common mode filter design and optimization method described in the present invention, wherein: the setting of the common-mode amplifier parameters to obtain the common-mode transformer circuit transfer function includes that the voltage output by the integration circuit module and the actual common-mode current have a K-fold relationship. In order to obtain the original common-mode current signal, the amplification factor A of the common-mode operational amplifier is set to 1 / K, and the amplification factor is jointly determined by the resistors R5 and R6.

[0027] The values ​​of parameters R6 and C2 are determined by the unity gain frequency f of the common-mode operational amplifier. t2 Calculated.

[0028] To prevent the operational amplifier from saturating, make the unity gain frequency more than 10 times greater than the highest noise frequency that needs to be filtered. All parameters are expressed as:

[0029]

[0030] Among them, A represents the amplification factor, R5 represents the resistance value, R6 represents the resistance value, C2 represents the capacitance value, and f b Indicates the upper cutoff frequency.

[0031] The complex frequency domain expression is expressed as:

[0032]

[0033] Among them, V CM (s) represents the Laplace transform of the common mode voltage, s represents the Laplace operator, and represents the frequency variable. cm (s) represents the Laplace transform of the common-mode current, V out (s) represents the Laplace transform of the output voltage, V out (s) represents the Laplace transform of the output voltage, C3 represents the capacitance value, L2 represents the self-inductance of the secondary winding, I cm (s) represents the Laplace transform of the common mode current.

[0034] The common-mode transformer circuit transfer function is obtained, and the expression is:

[0035]

[0036] Where H(s) represents the common-mode transformer circuit transfer function, V out (s) represents the output voltage in the Laplace domain.

[0037] 7 As a preferred solution of the infrared sensor anti-interference common mode filter design and optimization method described in the present invention, wherein: the design of common mode transformer circuit parameters and calculation of winding turns ratio include, in order to ensure that the common mode transformer circuit has a low-pass characteristic, the coefficient of the quadratic term of the transfer function numerator is set to 0.

[0038] The primary and secondary windings are wound on the same magnetic core, and the coupling coefficient is set to 1. The relationship is expressed as:

[0039]

[0040] Substituting the relationship into the transfer function:

[0041]

[0042] The turns ratio between the windings of the common-mode transformer is finally determined as:

[0043] N1:N2:N3=1:1:2

[0044] Among them, N1 represents the number of turns of the secondary winding of the common mode transformer, N2 represents the number of turns of the secondary winding of the common mode transformer, and N3 represents the number of turns of the primary winding of the common mode transformer.

[0045] 8A design and optimization system for anti-interference common mode filters of infrared sensors, characterized in that: it includes:

[0046] The coil parameter calculation module winds the Rogowski coil, calculates the relationship between the output voltage and the current change rate, and calculates the Rogowski coil parameters.

[0047] Set the integration circuit parameter module, calculate the relationship between the integration circuit output voltage and common-mode current, and set the integration circuit parameters.

[0048] Calculate the transfer function module, set the parameters of the common-mode amplifier, and obtain the common-mode transformer circuit transfer function.

[0049] Calculate the winding turns ratio module, design the common mode transformer circuit parameters, and calculate the winding turns ratio.

[0050] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0051] A computer-readable storage medium stores a computer program, which implements the steps of the method described above when executed by a processor.

[0052] The beneficial effects of the present invention are as follows: by optimizing the design of the Rogowski coil and the integral circuit, the external common-mode interference signal is effectively filtered out, ensuring accurate signal transmission. The parametric design method is adopted to simplify the circuit design and adjustment process, so that researchers can conduct experiments and optimization more conveniently. By optimizing the high-frequency band design and avoiding the resonance phenomenon, the measurement bandwidth of the Rogowski coil is significantly expanded, and the application range of the system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0054] Figure 1 An overall flow chart of a method for designing and optimizing an infrared sensor anti-interference common mode filter provided by the first embodiment of the present invention.

[0055] Figure 2An overall system diagram of a common-mode filter circuit for designing and optimizing an infrared sensor anti-interference common-mode filter provided by the first embodiment of the present invention.

[0056] Figure 3 An overall design flow chart of an infrared sensor anti-interference common mode filter design and optimization method provided for the first embodiment of the present invention.

[0057] Figure 4 A structural diagram of a Rogowski coil for designing and optimizing an infrared sensor anti-interference common mode filter provided by the first embodiment of the present invention.

[0058] Figure 5 A common-mode transformer circuit diagram after eliminating mutual inductance coupling in a design and optimization method for an infrared sensor anti-interference common-mode filter provided by the first embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0060] Example 1

[0061] Reference Figure 1 to Figure 5 , as an embodiment of the present invention, provides a design and optimization method for an infrared sensor anti-interference common mode filter, comprising:

[0062] S1: Wind the Rogowski coil, calculate the relationship between the output voltage and current change rate, and calculate the parameters of the Rogowski coil.

[0063] It should be noted that the Rogowski coil is made of several turns of wire evenly and symmetrically wound on a non-ferromagnetic material of a certain shape and size. The primary conductor vertically passes through the center of the frame. When a changing current flows through the conductor, a changing magnetic field is generated around the conductor. According to the principle of electromagnetic induction, an induced electromotive force is generated at the output end of the Rogowski coil. The structure of the Rogowski coil is shown in the figure below. Figure 3 shown.

[0064] The output voltage v(t) is proportional to the rate of change of the current to be measured, expressed as:

[0065]

[0066] Among them, cm(t) / dt represents the rate of change of the current to be measured, a represents the inner diameter of the coil, b represents the outer diameter of the coil, h represents the height of the coil, N represents the number of turns of the coil, φ represents the magnetic flux, μ0 represents the magnetic permeability of vacuum, and M represents the mutual inductance between the coil and the conductor to be measured.

[0067] The inner diameter, outer diameter and height of the coil are directly measured, and the number of turns N of the coil is expressed as:

[0068]

[0069] Wherein, p represents the wire diameter of the copper wire.

[0070] Furthermore, the Rogowski coil itself exhibits differential characteristics in the low and medium frequency bands and resonates in the high frequency band. The first resonance point f l As the upper limit of the measurement bandwidth of the Rogowski coil, f l It is calculated from the parasitic parameters inside the Rogowski coil. In order to maintain a certain margin, the first resonance point f l than the upper limit of the noise frequency band f high The relationship between the first resonance point fl and the upper limit of the noise frequency band fhigh is expressed as:

[0071] f l ≥10f high

[0072] The first resonance point f l than the upper limit of the noise frequency band f high 10 times higher.

[0073] S2: Calculate the relationship between the output voltage and common-mode current of the integration circuit and set the integration circuit parameters.

[0074] For the integration circuit, the voltage and the integrated common-mode current are proportional, and the proportionality coefficient K is determined by the integration circuit structure. The relationship between the output voltage and the common-mode current of the integration circuit is expressed as:

[0075]

[0076] Among them, μ o represents the output voltage of the integration circuit, R1 represents the resistance value, C1 represents the capacitance value, K represents the proportional coefficient, and t represents the time.

[0077] It should be noted that to design the parameters of the integration circuit, we first need to give the value of the resistor R1, which is generally in the kilo-ohm range. According to the unit gain frequency f given in the operational amplifier manual, t1 The size of C1 can be set. Resistor R2 determines the lower cutoff frequency f of the Rogowski coil sensor. a , this frequency is higher than the minimum noise frequency f lowAt the same time, R2 prevents the low-frequency signal from gaining too much, and its resistance should be large enough, usually in the megohm level. Finally, consider the performance of the operational amplifier. To prevent the operational amplifier from saturating, the unit gain frequency should be at least 10 times greater than the highest noise frequency that needs to be filtered out. The various parameters are expressed as:

[0078]

[0079] Among them, f t1 represents the unity gain frequency, f a Represents the lower cutoff frequency, f low Indicates the minimum noise frequency band, f high Indicates the highest noise frequency.

[0080] Furthermore, for the proportional amplifier circuit, this circuit is composed of a first-order common-phase operational amplifier, and there is an upper cutoff frequency. Different from the traditional common-phase operational amplifier, the first-order RC common-phase operational amplifier has a small capacitor of the order of pF connected in parallel at the feedback resistor end to offset the influence of the parasitic capacitance at the negative input end of the operational amplifier and prevent the operational amplifier from oscillating. In addition, this structure acts as a low-pass filter, and the addition of a small capacitor can also more accurately design the upper cutoff frequency f b .

[0081] S3: Set the parameters of the common-mode amplifier to obtain the common-mode transformer circuit transfer function.

[0082] It should be noted that, from the above analysis, the voltage output by the integration circuit module is K times the actual common-mode current. In order to obtain the original common-mode current signal, the amplification factor A of the in-phase operational amplifier should be set to 1 / K, and this amplification factor is jointly determined by resistors R5 and R6. Then, the values ​​of R6 and C2 are designed. The parameters of the two can be determined by the unit gain frequency f of the in-phase operational amplifier. t2 Finally, consider the performance of the operational amplifier. To prevent the operational amplifier from saturating, the unity gain frequency should be at least 10 times greater than the highest noise frequency that needs to be filtered out. Combining the above analysis, all parameters can be listed as:

[0083]

[0084] Among them, A represents the amplification factor, R5 represents the resistance value, R6 represents the resistance value, C2 represents the capacitance value, and f b Indicates the upper cutoff frequency.

[0085] Furthermore, for the common-mode transformer circuit, the secondary side of the common-mode transformer is connected to the output end of the power line, and the positive and negative power lines are each wound with a winding, and the two windings are the same. The primary side is connected to the output end of the proportional amplifier circuit. Since the common-mode components transmitted by the power supply are all relative to the ground, the two windings on the secondary side can be equivalent to one winding. Assuming that the common-mode current flowing into the infrared sensor can be completely eliminated, the common-mode transformer circuit is decoupled, such as Figure 5 shown.

[0086] The complex frequency domain expression is expressed as:

[0087]

[0088] Among them, V CM (s) represents the Laplace transform of the common mode voltage, s represents the Laplace operator, and represents the frequency variable. cm (s) represents the Laplace transform of the common-mode current, V out (s) represents the Laplace transform of the output voltage, V out (s) represents the Laplace transform of the output voltage, C3 represents the capacitance value, L2 represents the self-inductance of the secondary winding, I cm (s) represents the Laplace transform of the common mode current.

[0089] The common-mode transformer circuit transfer function is obtained, and the expression is:

[0090]

[0091] Where H(s) represents the common-mode transformer circuit transfer function, V out (s) represents the output voltage in the Laplace domain.

[0092] S4: Design the common-mode transformer circuit parameters and calculate the winding turns ratio.

[0093] To ensure that the common-mode transformer circuit has a low-pass characteristic, the coefficient of the quadratic term in the numerator of the transfer function is set to 0.

[0094] The primary and secondary windings are wound on the same magnetic core, and the coupling coefficient is set to 1. The relationship is expressed as:

[0095]

[0096] Substituting the relationship into the transfer function:

[0097]

[0098] The turns ratio between the windings of the common-mode transformer is finally determined as:

[0099] N1:N2:N3=1:1:2

[0100] Among them, N1 represents the number of turns of the secondary winding of the common mode transformer, N2 represents the number of turns of the secondary winding of the common mode transformer, and N3 represents the number of turns of the primary winding of the common mode transformer.

[0101] The above embodiments also include a design and optimization system for an infrared sensor anti-interference common mode filter, specifically:

[0102] The coil parameter calculation module winds the Rogowski coil, calculates the relationship between the output voltage and the current change rate, and calculates the Rogowski coil parameters.

[0103] Set the integration circuit parameter module, calculate the relationship between the integration circuit output voltage and common-mode current, and set the integration circuit parameters.

[0104] Calculate the transfer function module, set the parameters of the common-mode amplifier, and obtain the common-mode transformer circuit transfer function.

[0105] Calculate the winding turns ratio module, design the common mode transformer circuit parameters, and calculate the winding turns ratio.

[0106] The computer device may be a server. The computer device includes a processor, a memory, an input / output interface (I / O for short) and a communication interface. The processor, the memory and the input / output interface are connected via a system bus, and the communication interface is connected to the system bus via the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data cluster data of a power monitoring system. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a method is implemented.

[0107] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0108] Example 2

[0109] An embodiment of the present invention provides a design and optimization method and system for an infrared sensor anti-interference common mode filter. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0110] In order to verify the effectiveness of our invention, we conducted several experiments, and the experimental equipment included infrared sensors, Rogowski coils, integration circuits, in-phase amplifiers and common-mode transformers. The test subjects selected multiple environments with different frequencies and interference intensities, and compared the existing technology with our invention.

[0111] The detailed process of the test is as follows:

[0112] Two infrared sensor systems were prepared. One group used a common mode filter designed with existing technology. The existing technology referred to the anti-interference design of infrared sensors based on traditional RC filters. Traditional RC filters filter signals through a simple combination of resistors and capacitors, but their anti-interference performance is limited in high-frequency interference environments. The other group used an anti-interference common mode filter based on Rogowski coil signal sampling. Each system includes an infrared sensor, a signal acquisition circuit, and an anti-interference common mode filter.

[0113] The Rogowski coil design invented by us includes winding a number of turns of wire evenly on a non-ferromagnetic material, determining the inner diameter (a), outer diameter (b) and height (h). The inner diameter of the wire used is 10mm, the outer diameter is 20mm, the height is 30mm, and the total number of turns is 100. By calculating the mutual inductance (M), the relationship between the coil output voltage and the current change rate is obtained.

[0114] The design of the integration circuit of our invention includes setting the integration circuit parameters, selecting the resistor R1 as 1kΩ and the capacitor C1 as 100nF, calculating the lower cutoff frequency (fa) and the unity gain frequency (ft1), and ensuring that the circuit works stably within the expected frequency band.

[0115] The design of the common-phase amplifier invented by our party includes setting the common-phase amplifier parameters, selecting the resistor R5 to be 10kΩ, the resistor R6 to be 100kΩ, and the capacitor C2 to be 10pF, calculating the upper cutoff frequency (fb), and optimizing the circuit design to avoid high-frequency oscillation.

[0116] The common mode transformer design invented by us includes calculating the self-inductance (L2) and mutual inductance (M) of the secondary winding, and designing the circuit parameters of the common mode transformer to ensure that it has good low-pass characteristics.

[0117] Three environments with different interference strengths and frequencies were selected, namely low frequency (50Hz), medium frequency (500Hz) and high frequency (5kHz). In each environment, the output signal quality of the two infrared sensor systems was recorded. In each experimental environment, the output voltage and signal error of the infrared sensor were recorded. The signal transmission quality of the two systems under different frequencies and interference strengths was compared. The experimental results are shown in Table 1.

[0118] Table 1 Experimental results

[0119]

[0120] By comparing the data in the table, it can be clearly seen that our invention is superior to the prior art in many aspects.

[0121] In low frequency, medium frequency and high frequency environments, the output voltage of our invention is more stable than that of the prior art. In particular, in high frequency environments, the output voltage of our invention is 0.65V, which is closer to the actual value than the 0.7V of the prior art, indicating that it has stronger anti-interference ability.

[0122] Signal error is an important indicator for evaluating anti-interference performance. In all frequency ranges, the signal error of our invention is significantly lower than that of the existing technology. For example, in a high-frequency environment, the signal error of the existing technology is as high as 25%, while our invention is only 10%, which greatly improves the accuracy of signal transmission.

[0123] The signal bandwidth of our invention is 2000Hz, which is twice that of the existing technology. This means that our invention can work effectively in a wider frequency range, expanding the application scenarios.

[0124] The measurement accuracy of our invention in different frequency environments is higher than that of the prior art. In low-frequency environments, the measurement accuracy is improved by 15 percentage points, and in high-frequency environments, it is improved by 20 percentage points, which shows the stability and reliability of our invention in different working environments.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A design and optimization method for an infrared sensor anti-interference common mode filter, characterized in that: include: Wind the Rogowski coil, calculate the relationship between the output voltage and the current change rate, and calculate the parameters of the Rogowski coil; Calculate the relationship between the output voltage and common-mode current of the integration circuit and set the integration circuit parameters; Set the parameters of the common-mode amplifier to obtain the transfer function of the common-mode transformer circuit; Design the common-mode transformer circuit parameters and calculate the winding turns ratio.

2. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 1, characterized in that: The winding of the Rogowski coil and the calculation of the relationship between the output voltage and the current change rate include: the Rogowski coil is made of a wire evenly and symmetrically wound on a non-ferromagnetic material, and the primary side conductor vertically passes through the center of the skeleton. When a changing current flows through the conductor, a changing magnetic field is generated around the conductor, and the output voltage v(t) is proportional to the change rate of the current to be measured, which is expressed as: Among them, cm (t) / dt represents the rate of change of the current to be measured, a represents the inner diameter of the coil, b represents the outer diameter of the coil, h represents the height of the coil, N represents the number of turns of the coil, φ represents the magnetic flux, μ0 represents the magnetic permeability of vacuum; M represents the mutual inductance between the coil and the conductor to be measured.

3. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 2, characterized in that: The calculation of the Rogowski coil parameters includes directly measuring the inner diameter, outer diameter and height of the coil, and the number of turns N of the coil is expressed as: Where p represents the wire diameter of the copper wire; The first resonance point fl is used as the upper limit of the measurement bandwidth of the Rogowski coil. fl is calculated from the internal parasitic parameters of the Rogowski coil. In order to maintain a certain margin, the relationship between the first resonance point fl and the upper limit of the noise frequency band fhigh is expressed as: f l ≥10f high The first resonance point f l than the upper limit of the noise frequency band f high 10 times higher.

4. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 3, characterized in that: The calculating the relationship between the output voltage and the common-mode current of the integration circuit includes that, for the integration circuit, the voltage and the integrated common-mode current are in a proportional relationship, and the proportionality coefficient K is determined by the structure of the integration circuit; The relationship between the output voltage and common-mode current of the integrator circuit is expressed as: Among them, μ o represents the output voltage of the integration circuit, R1 represents the resistance value, C1 represents the capacitance value, K represents the proportional coefficient, and t represents the time.

5. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 4, characterized in that: The setting of the integration circuit parameters includes directly measuring the value of the resistor R1 and setting the value of C1 according to the unit gain frequency ft1; the resistor R2 determines the lower limit cutoff frequency f of the Rogowski coil sensor. a , f a The minimum noise frequency f low Ten times smaller; To prevent the operational amplifier from saturating, make the unity gain frequency more than 10 times greater than the highest noise frequency that needs to be filtered; all parameters are expressed as: Among them, f t1 represents the unity gain frequency, f a Represents the lower cutoff frequency, f low Indicates the minimum noise frequency band, f high Indicates the highest noise frequency.

6. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 5, characterized in that: The common-mode transformer circuit transfer function is obtained by setting the parameters of the common-mode amplifier, including that the voltage output by the integration circuit module is K times the actual common-mode current; in order to obtain the original common-mode current signal, the amplification factor A of the common-mode operational amplifier is set to 1 / K, and the amplification factor is jointly determined by the resistors R5 and R6; The values ​​of parameters R6 and C2 are determined by the unity gain frequency f of the common-mode operational amplifier. t2 Calculated; To prevent the operational amplifier from saturating, make the unity gain frequency more than 10 times greater than the highest noise frequency that needs to be filtered; all parameters are expressed as: Among them, A represents the amplification factor, R5 represents the resistance value, R6 represents the resistance value, C2 represents the capacitance value, and f b represents the upper cutoff frequency; The complex frequency domain expression is expressed as: Among them, V CM (s) represents the Laplace transform of the common mode voltage, s represents the Laplace operator, and I represents the frequency variable; cm (s) represents the Laplace transform of the common-mode current, V out (s) represents the Laplace transform of the output voltage, V out (s) represents the Laplace transform of the output voltage, C3 represents the capacitance value, L2 represents the self-inductance of the secondary winding, I cm (s) represents the Laplace transform of the common mode current; The common-mode transformer circuit transfer function is obtained, and the expression is: Where H(s) represents the common-mode transformer circuit transfer function, V out (s) represents the output voltage in the Laplace domain.

7. The infrared sensor anti-interference common mode filter design and optimization method as claimed in claim 6, characterized in that: The design of the common mode transformer circuit parameters and the calculation of the winding turns ratio include: to ensure that the common mode transformer circuit has a low-pass characteristic, the coefficient of the quadratic term of the transfer function numerator is set to 0; The primary and secondary windings are wound on the same magnetic core, and the coupling coefficient is set to 1. The relationship is expressed as: Substituting the relationship into the transfer function: The turns ratio between the windings of the common-mode transformer is finally determined as: N1:N2:N3=1:1:2 Among them, N1 represents the number of turns of the secondary winding of the common mode transformer, N2 represents the number of turns of the secondary winding of the common mode transformer, and N3 represents the number of turns of the primary winding of the common mode transformer.

8. A design and optimization system for an infrared sensor anti-interference common mode filter using the method according to any one of claims 1 to 7, characterized in that: The coil parameter calculation module winds the Rogowski coil, calculates the relationship between the output voltage and the current change rate, and calculates the Rogowski coil parameters; Set up an integration circuit parameter module, calculate the relationship between the integration circuit output voltage and the common-mode current, and set the integration circuit parameters; Calculate the transfer function module, set the parameters of the common-mode amplifier, and obtain the transfer function of the common-mode transformer circuit; Calculate the winding turns ratio module, design the common mode transformer circuit parameters, and calculate the winding turns ratio.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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