Broadband electromagnetic sensor and method of manufacturing the same

Abstract

A broadband electromagnetic sensor includes: an amplifier circuit having a gain of at least 26 dB over its bandwidth; and a sensing portion electrically connected to the amplifier circuit and including a coil array structure comprising a plurality of coils, wherein each of the plurality of coils has a different length from the other coils and detects a signal having a frequency within its own frequency bandwidth, such that the plurality of coils together can detect a signal having a frequency within the frequency bandwidth of the sensor, and wherein the frequency bandwidth of the sensor ranges from approximately 1 MHz to 100 MHz, enabling the sensor to detect partial discharge from a high-voltage device without physical contact with the high-voltage device.

Description

Technical Field

[0001] This disclosure relates to a broadband electromagnetic sensor and a method for manufacturing the same. Background Technology

[0002] High-voltage power transmission and transformation equipment is a crucial component of the power system, and its operational stability is directly related to the smooth operation of the power grid. Any grid failure will have a significant impact on industry and society. Insulation aging or defects in high-voltage power equipment can manifest as partial discharge, which, if left unchecked, can have continuous physical and chemical effects. Prolonged partial discharge accelerates insulation damage and potentially harms high-voltage power equipment. To ensure the safe and reliable operation of high-voltage power equipment, it is necessary to implement continuous early monitoring of partial discharge to detect faults as early as possible and to carry out preventative replacement or repair of equipment. Partial discharge is a localized electrical discharge that only partially bridges the insulation between conductors and is usually the result of localized electrical stress concentration within or on the surface of the insulator. Typically, partial discharge manifests as pulses with a duration much shorter than 1 microsecond. Due to the very short pulse duration, the frequency range of the discharge signal can span from direct current (DC) to several gigahertz (GHz). The harmful effects of partial discharge on electrical insulation are cumulative. It is considered one of the most decisive indicators of electrical insulation degradation. In particular, partial discharge monitoring is an important part of the insulation maintenance of the covered conductors of medium-voltage overhead power lines. The insulation of the covered conductor prevents phase-to-phase short circuits in the event of a fault. Because the abnormal leakage current is extremely small, standard digital relay protection cannot respond to such low currents.

[0003] Currently available methods and systems for detecting partial discharge include ultrasonic methods; however, ultrasonic methods have low sensitivity and are susceptible to environmental noise. Chemical methods are not suitable for continuous monitoring and cannot detect the severity of partial discharge. Optical methods are only applicable to transparent insulators. Existing current sensors are susceptible to electromagnetic interference. For example, the Rogowski coil, due to its air-core skeleton, is commonly used to measure high-frequency and large currents. The air-core skeleton makes the Rogowski coil a very popular current sensor due to its many advantages, such as no magnetic saturation, light weight, simple structure, wide dynamic bandwidth, non-invasive isolation, and linearity. Sensitivity and accuracy are key indicators for evaluating the performance of a Rogowski coil. However, the accuracy of a Rogowski coil is susceptible to the coil's structure and the frequency of the current being measured. Furthermore, the position and shape of the primary conductor can affect the accuracy of the Rogowski coil.

[0004] A high-frequency current transformer (HFCT) sensor detection method exists, which is widely used for partial discharge detection. In use, the HFCT sensor is clamped around the cable core rather than the earth sheath, as this achieves a better signal-to-noise ratio. The HFCT sensor has a split-core structure, which consists of an induction coil with a ferromagnetic core. The applied HFCT sensor has a bandwidth of approximately 5 MHz at a -3 dB cutoff frequency and approximately 100 MHz at an -3 dB cutoff frequency. This is to avoid capturing field noise below 1 MHz. The HFCT sensor has the advantage of allowing installation during operation, and the directionality of the partial discharge current pulse can aid in partial discharge localization. However, the HFCT sensor needs to be clamped to the cable, is bulky, has a heavy magnetic core, and is susceptible to high current saturation. This makes it difficult to apply in many situations where space is limited or the cable is inaccessible.

[0005] Therefore, it is desirable to provide an efficient and effective solution for partial discharge detection as a valuable tool for detecting abnormal events and anomalies in medium-voltage overhead lines, so as to establish preventive maintenance plans before electrical components fail. Summary of the Invention

[0006] This application discloses a broadband electromagnetic sensor using electromagnetic coupling technology based on multimode resonator theory. In an exemplary embodiment, the sensor is capable of detecting signals with frequencies, for example, in the range of approximately 1 MHz to 100 MHz. In an exemplary embodiment of use, the sensor is configured to detect partial discharges from high-voltage transmission and transformation equipment without requiring physical contact between the sensor and the equipment. This low-cost, lightweight sensor is unaffected by high-current saturation, does not require the use of any magnets, and is capable of detecting partial discharges at a distance of at least one meter from the source of the partial discharge, without needing to be fixed around the equipment's cables.

[0007] According to a first aspect, a method for manufacturing a broadband electromagnetic sensor is provided. The broadband electromagnetic sensor includes an amplifier circuit connected to a sensing portion, the sensing portion including a coil array structure of a plurality of coils, wherein each coil is capable of detecting a signal having a frequency within its own frequency bandwidth, and wherein the coil array structure is capable of detecting a signal having a frequency within the frequency bandwidth of the broadband electromagnetic sensor. The method includes the following steps:

[0008] (a) The sensing part is represented as a theoretical circuit, wherein each of the multiple coils is represented by a theoretical inductor with theoretical inductance, and a circuit simulation is performed on the theoretical circuit to obtain the circuit simulation results of the theoretical circuit and to obtain the theoretical inductance of each coil.

[0009] (b) Calculate the length of each coil based on the theoretical inductance of each coil using a predetermined method, and draw an integrated layout of multiple coils based on the calculated length of each coil;

[0010] (c) Use electromagnetic simulation software to create a coil model for each coil in the integrated layout and perform electromagnetic simulation on the coil model to obtain the electromagnetic simulation results of the coil model;

[0011] (d) Create a coil equivalent circuit model for each coil model, wherein each coil model is represented as an inductor connected in parallel with a capacitor and in series with a resistor, and perform circuit simulation on the coil equivalent circuit model to obtain the circuit simulation results of the coil equivalent circuit model, and determine the inductance, resistance and capacitance for each coil model when the circuit simulation results of the coil equivalent circuit model best match the electromagnetic simulation results of the coil model.

[0012] (e) Use the two coil models already created in step (c) to create a dual-coil model of the two coils in the integrated layout, and perform electromagnetic simulation on the dual-coil model to obtain the electromagnetic simulation results of the dual-coil model;

[0013] (f) Using the two coil equivalent circuit models already created in step (d), a dual-coil equivalent circuit model of the dual-coil model is created, wherein the dual-coil equivalent circuit model includes the mutual inductance in the dual-coil model, and a circuit simulation is performed on the dual-coil equivalent circuit model to obtain the circuit simulation results of the dual-coil equivalent circuit model, and the mutual inductance in the dual-coil model is determined when the circuit simulation results of the dual-coil equivalent circuit model best match the electromagnetic simulation results of the dual-coil model.

[0014] (g) Repeat steps (e) and (f) for each different pair of coils in the integrated layout to determine the mutual inductance between each different pair of coils in the integrated layout;

[0015] (h) Use all the coil equivalent circuit models created in step (d) to create an integrated layout equivalent circuit model, wherein the integrated layout equivalent circuit model includes the mutual inductance between each different pair of coils in the integrated layout, and perform circuit simulation on the integrated layout equivalent circuit model to obtain the circuit simulation results of the integrated layout equivalent circuit model, and determine the optimized inductance for each coil model when the circuit simulation results of the integrated layout equivalent circuit model best match the circuit simulation results of the theoretical circuit;

[0016] (i) Recalculate the length of each coil using a predetermined method based on the optimized inductance of each coil, and redraw the integrated layout of multiple coils based on the recalculated length of each coil; and

[0017] (j) Fabricate a coil array structure on a printed circuit board based on a redrawn integrated layout.

[0018] The theoretical circuit in step (a) may include a stepped structure similar to a bandpass filter, wherein each element of the stepped structure includes one of the theoretical inductors electrically connected to the theoretical capacitor, and wherein each element is configured according to a preselected response type.

[0019] The preselected response type can be one of the following: Butterworth response, Chebyshev response, and elliptic response.

[0020] The method further includes: after step (h), creating a circuit verification model of the two coils including the confirmed mutual inductance between the two coils, and performing circuit simulation on the circuit verification model to obtain the circuit simulation result of the circuit verification model, wherein the matching of the circuit simulation result of the circuit verification model with the circuit simulation result of the dual-coil equivalent circuit model confirms the mutual inductance between the two coils.

[0021] The circuit verification model for integrated layout can include a T-type circuit.

[0022] Electromagnetic simulation results and circuit simulation results can include the changes in input impedance and scattering parameters with frequency.

[0023] The method may also include: fabricating an amplifier circuit on a printed circuit board and connecting the amplifier circuit to a coil array structure.

[0024] The method may further include: after step (i), using electromagnetic simulation software to create a redrawn integrated layout model of the redrawn integrated layout, performing electromagnetic simulation on the redrawn integrated layout physical model to obtain the electromagnetic simulation results of the redrawn integrated layout physical model, and comparing the electromagnetic simulation results of the redrawn integrated layout physical model with the circuit simulation results of the theoretical circuit to confirm the length of each recalculated coil.

[0025] According to a second aspect, a broadband electromagnetic sensor is provided, comprising: an amplifier circuit having a gain of at least 26 dB through its bandwidth; and a sensing portion comprising a coil array structure of a plurality of coils, wherein each of the plurality of coils has a different length from the other coils, and each coil detects a signal having a frequency within its own frequency bandwidth, such that the plurality of coils together can detect a signal having a frequency within the frequency bandwidth of the sensor, and wherein the frequency bandwidth of the sensor ranges from about 1 MHz to 100 MHz, such that the sensor can detect partial discharge from a high-voltage device without physical contact with the high-voltage device.

[0026] The coil array structure can be configured as an integrated layout on a printed circuit board, wherein the integrated layout is optimized to minimize the area required for the printed circuit board to support the coils.

[0027] Each coil can be represented by an equivalent circuit model, which includes a capacitor connected in parallel with the inductor and an inductor connected in series with a resistor.

[0028] The sensing part can be represented by an equivalent circuit model that incorporates the mutual inductance between each different pair of coils in the coil array.

[0029] Coil array structures include one of the following: rectangular shape, circular shape, or three-dimensional structure.

[0030] Broadband electromagnetic sensors can be manufactured using the method described in the first aspect. Attached Figure Description

[0031] In order to fully understand the invention and to readily put it into practice, exemplary embodiments of the invention will now be described by way of non-limiting examples, with reference to the accompanying illustrative drawings.

[0032] Figure 1 It shows a schematic diagram of a single coil and a curve of its corresponding impedance parameters when the single coil detects an electromagnetic wave signal.

[0033] Figure 2 It should be by Figure 1 The curves showing the input and output magnitudes in the time and frequency domains of the single-coil detection of the input electromagnetic wave signal.

[0034] Figure 3 It is a schematic diagram of a dual-coil system and a graph showing the corresponding impedance parameters when the dual-coil system detects an electromagnetic wave signal.

[0035] Figure 4 When Figure 3 The curves showing the input and output magnitudes in the time and frequency domains of the dual-coil system detecting the input electromagnetic wave signal are shown.

[0036] Figure 5 This is an exemplary integrated layout equivalent circuit model of an exemplary broadband electromagnetic sensor.

[0037] Figure 6 This is an exemplary bandpass filter ladder structure circuit representing the radiator or broadband sensing section of a broadband electromagnetic sensor.

[0038] Figure 7 This is a schematic diagram of a printed circuit board assembly of an exemplary broadband electromagnetic sensor, including a sensing portion connected to an amplifier circuit.

[0039] Figure 8 It is based on Figure 7 A photograph of a printed circuit board assembly manufactured according to a schematic diagram.

[0040] Figure 9 It is used for Figure 7 and Figure 8 A schematic diagram of the integrated layout of an exemplary four-coil system for the sensing portion of a broadband electromagnetic sensor.

[0041] Figure 10 yes Figure 5 The input impedance curve of the integrated layout equivalent circuit model.

[0042] Figure 11 This is an exemplary embodiment of the amplifier circuit for a broadband electromagnetic sensor.

[0043] Figure 12(a) is Figure 9 An exemplary coil model of the first coil of an exemplary four-coil system.

[0044] Figure 12(b) is a first exemplary coil equivalent circuit model of the coil model in Figure 12(a).

[0045] Figure 12(c) is a graph of the input impedance of the coil model in Figure 12(a).

[0046] Figure 12(d) is a second exemplary coil equivalent circuit model of the coil model in Figure 12(a).

[0047] Figure 12(e) is a graph of the input impedance of the coil equivalent circuit model in Figure 12(c).

[0048] Figure 13(a) is Figure 9 An exemplary coil model of an exemplary second coil in a four-coil system.

[0049] Figure 13(b) is a graph of the input impedance of the coil model in Figure 13(a).

[0050] Figure 13(c) is an exemplary coil equivalent circuit model of the coil model in Figure 13(a).

[0051] Figure 13(d) is a graph of the input impedance of the coil equivalent circuit model in Figure 13(c).

[0052] Figure 14(a) is an exemplary dual-coil model of an exemplary dual-coil system including the coil model of Figure 13(a) and the coil model of Figure 14(a).

[0053] Figure 14(b) is a graph of the input impedance of the dual-coil model in Figure 14(a).

[0054] Figure 14(c) is an exemplary dual-coil equivalent circuit model of the dual-coil model in Figure 14(a).

[0055] Figure 14(d) is a graph of the input impedance of the dual-coil equivalent circuit model in Figure 14(c).

[0056] Figure 14(e) is an exemplary T-type circuit verification model of the exemplary dual-coil system of Figure 14(a).

[0057] Figure 14(f) shows the MATLAB calculation of the input impedance of the T-type circuit verification model in Figure 14(e).

[0058] Figure 15 It is the manufactured including Figure 8 Photograph of a broadband electromagnetic sensor on a printed circuit board assembly.

[0059] Figure 16 This is a schematic diagram of the assembly steps for a broadband electromagnetic sensor.

[0060] Figure 17 It is used for testing the manufactured Figure 16 A schematic diagram of the setup platform for the broadband electromagnetic sensor.

[0061] Figure 18 When partial discharge is detected, an HFCT sensor is used, and the manufactured... Figure 16 A graph of an exemplary measurement waveform obtained by a broadband electromagnetic sensor.

[0062] Figure 19 These are photos of actual high-voltage equipment, which has multiple cables attached to it. Figure 16 The sensor unit.

[0063] Figure 20 From Figure 19 The curve of the phase-resolved partial discharge pattern obtained from the platform.

[0064] Figure 21 This is a flowchart of an exemplary method for producing a broadband electromagnetic sensor. Detailed Implementation

[0065] Reference Figures 1 to 21 Exemplary embodiments of a method 90 for producing a broadband electromagnetic sensor 10 and exemplary embodiments of the broadband electromagnetic sensor 10 are described, wherein the same reference numerals are used in the drawings to denote the same or similar components.

[0066] Usually, such as Figure 1 The single coil shown has a narrow frequency bandwidth and a high quality factor. When a plane electromagnetic (EM) wave is in such a state... Figure 1 When radiation occurs at the single coil shown, from a frequency domain perspective, if the input spectrum is wide, the output spectrum is narrow; and from a time domain perspective, if the input signal is a chirped signal, the output signal is a sinusoidal signal with diminishing magnitude, such as... Figure 2 As can be seen in the simulation results, the single coil resonates at a narrow frequency bandwidth, such as... Figure 1 As can be seen in the image. When a plane EM wave is in such a state... Figure 3 When radiating from the dual-coil system shown, from the frequency domain perspective, if the input spectrum remains wide, the output spectrum has two narrow bands; and from the time domain perspective, if the input signal is also a chirped signal, the output signal has more frequency components, such as... Figure 4 As shown in the figure. Simulation results verify that the dual-coil system resonates at two narrow bands, as... Figure 3 As shown in the image.

[0067] By increasing the number of cascaded or parallel coils in the system, multiple resonant frequencies can be generated, allowing it to receive / radiate time-domain signals of multiple frequencies. Due to the non-flat frequency response, the system can effectively receive / radiate signals with discontinuous frequencies. Therefore, as... Figure 5 As shown in the exemplary integrated layout equivalent circuit model, the broadband electromagnetic sensor 10 of this disclosure is made of a plurality of coils and a plurality of added capacitors. In an exemplary embodiment, the broadband electromagnetic sensor 10 includes, as shown in the example, coils and added capacitors. Figure 7 and Figure 8 The amplifier circuit 20 is electrically connected to the sensing section 30 shown in the printed circuit board assembly. Figure 6 Amplifier circuit 20 may include added, associated enhancement circuitry to amplify the input analog signal, the enhancement circuitry having a gain of at least 26 dB across its bandwidth. Sensing section 30 includes multiple planar or three-dimensional coils or inductors (31, 32, 33, 34). Figure 9 The coil array structure 37 is accompanied by one or more capacitors to tune its resonant frequency. Each coil 31, 32, 33, 34 is capable of detecting signals with frequencies within its own frequency bandwidth, and the coil array structure 37 is capable of detecting signals with frequencies within the frequency bandwidth of the broadband electromagnetic sensor 10. The desired center frequency and bandwidth of each coil 31, 32, 33, 34 relate to the order of the bandpass filter. The scattering parameters of the sensing section 30 are... Figure 10 As shown in the figure, the broadband sensing features were obtained.

[0068] In an exemplary method 90 for producing a broadband electromagnetic sensor 10 Figure 21 In this circuit, the sensing part 30 can be represented as a theoretical circuit 39, such as... Figure 11As shown. In theoretical circuit 39, each of the plurality of coils 31, 32, 33, 34 can be represented by a theoretical inductor having a self-inductance (or theoretical inductance) L'. Theoretical circuit 39 may include a stepped structure similar to a bandpass filter, wherein each element of the stepped structure (indicated by dashed lines) includes one of the theoretical inductors electrically connected to a theoretical capacitor having a theoretical capacitance C'. Each element is configured according to a preselected response type. For example, the response type may be a Butterworth response, a Chebyshev response, or an elliptic response. The theoretical inductors and theoretical capacitors of each element may be connected in series or in parallel with each other according to the preselected response type, and the elements in the stepped structure may have different response types from each other.

[0069] Based on the selected frequency response type, center frequency, and bandwidth of sensor 10, circuit simulation of theoretical circuit 39 is performed to obtain the circuit simulation results of theoretical circuit 39 and the theoretical inductance L'(901, Figure 21 This allows us to determine the order and theoretical element values ​​L' and C' of each element in the ladder-structured theoretical circuit 39. The circuit simulation results can include the input impedance of the theoretical circuit 39.

[0070] Based on the theoretical inductance L' obtained for each coil 31, 32, 33, 34, known methods (such as those described in the publication "H. Greenhouse, 'Design of Planar Rectangular Microelectronic Inductors,' in IEEE Transactions on Parts, Hybrids, and Packaging, vol. 10, no. 2, pp. 101-109, June 1974") can be applied to estimate the length of each coil 31, 32, 33, 34 based on its self-inductance. In other words, a predetermined method can be used to calculate the length of each coil 31, 32, 33, 34. Other exemplary methods for calculating coil lengths based on the theoretical inductance L' of coils 31, 32, 33, and 34 can be found in the following publications: “SD Barman, AW Reza, N. Kumar, Md. E. Karim, AB Munir, 'Wireless powering by magnetic resonant coupling: Recent trends in wireless power transfer system and its applications,' Renewable and Sustainable Energy Reviews, 2015' and “T. Imura and Y. Hori, 'Maximizing air gap and efficiency of magnetic resonant coupling for wireless power transfer using equivalent circuit and Neumann formula,' IEEE Transactions on Industrial Electronics, vol. 58, no. 10, Oct. 2011". After calculating the length of each coil, an integrated layout 38 of multiple coils 31, 32, 33, and 34 is drawn based on the calculated length of each coil. Figure 9 (902, Figure 21 Preferably, the integrated layout 38 minimizes the area of ​​the printed circuit board 50 on which the actual coils of the coil array structure 27 will be fabricated.

[0071] Typically, after printing coils 31, 32, 33, and 34 on a printed circuit board, before connecting them together vias and traces, simulations (electromagnetic and circuit simulations) are performed on the coils 31, 32, 33, and 34, represented by theoretical inductors 100, 200, 300, and 400, to determine the actual self-inductance of the coils and their mutual inductance. Then, coils 31, 32, 33, and 34 are connected together with added capacitors as a stepped structure similar to a bandpass filter, and simulated again (electromagnetic simulation) to obtain electromagnetic simulation results, which may include variations in input impedance and scattering parameters with frequency. Simultaneously, using the obtained self-inductance and mutual inductance, an equivalent circuit model 45 of the sensing portion 30 of the broadband electromagnetic sensor 10 is constructed to obtain circuit simulation results. Figure 10 The circuit simulation results can include variations in input impedance and scattering parameters. Based on the fundamental definitions of conductor resistance and inter-conductor capacitance, the resistance and self-capacitance of coils 31, 32, 33, and 34 are calculated and considered in the equivalent circuit model 45 of the sensing section 30. Due to mutual inductance effects and modeling issues, the input impedance diagram of the equivalent circuit model 45 may differ somewhat from the theoretical input impedance of the theoretical circuit 39. After optimizing the equivalent circuit model 45 against theoretical values, the lengths of coils 31, 32, 33, and 34 are recalculated, and the design process is repeated to obtain a more accurate electromagnetic sensor 10. The above steps are described in more detail below.

[0072] In exemplary method 90, coil models 40 for each coil 31, 32, 33, 34 in the integrated layout 38 are created using electromagnetic simulation software (Figure 12(a), Figure 13(a)). Electromagnetic simulation is then performed on the coil models 40 to obtain the electromagnetic simulation results of the coil models 40 (Figure 12(c)). (903, Figure 21 A coil equivalent circuit model 41 (Fig. 12(b), Fig. 12(d)) is also created for each coil model 40, where each coil model 40 is represented as an inductor connected in parallel with a capacitor and in series with a resistor. Then, circuit simulation is performed on the coil equivalent circuit model 41 to obtain the circuit simulation results of the coil equivalent circuit model 41 (Fig. 12(e), Fig. 13(d)). For each coil model 40, given a resonance, its inductance, resistance, and capacitance are tuned until the circuit simulation results of the coil equivalent circuit model 41 (Fig. 12(e), Fig. 13(d)) and the electromagnetic simulation results of the coil model 40 (Fig. 12(c), Fig. 13(b)) achieve the best match (consistency) (904, Figure 21 This allows us to determine the inductance, resistance, and capacitance at the resonant point of each coil model 40 for each of the coils 31, 32, 33, and 34.

[0073] It is understood that mutual inductance will occur as long as two coils are placed close together. To determine the mutual inductance between each different pair of coil models in all previously created coil models 40, a dual-coil model 42 of two coils in the integrated layout 38 is first created using the two previously created coil models 40. In the exemplary embodiment of the dual-coil model 42 including two coil models 40, coil 1 and coil 2, shown in FIG14(a), the specifications of the dual-coil model 42 can be as follows: All trace widths are 1 mm. All gaps between traces are 0.4 mm. The copper trace thickness is 0.018 mm. Printed circuit board substrate: FR4 substrate with a dielectric constant Er of 4.2 and a thickness of 0.2 mm. Coil 1 has three turns and coil 2 has two turns. An external capacitor is connected in parallel to each coil, and then they are made to resonate at 10 MHz. The frequency range is 0.1 MHz to 10 MHz. Electromagnetic simulation is performed on the dual-coil model 42 to obtain the electromagnetic simulation results of the dual-coil model 42 shown in FIG14(b) (905, Figure 21 ).

[0074] Then, using the two previously created equivalent circuit models 41 of the related coils, a dual-coil equivalent circuit model 43 of the dual-coil model 42 is created. It is worth noting that, as shown in Figure 14(c), the dual-coil equivalent circuit model 43 includes the mutual inductance M from the dual-coil model 42. ab This can be achieved by adding coupling using a circuit simulation tool. By performing circuit simulation of the dual-coil equivalent circuit model 43 to obtain the circuit simulation results of the dual-coil equivalent circuit model 43 shown in Figure 14(d), the mutual inductance M can be... ab Tuning is performed to achieve the best match between the circuit simulation results of the dual-coil equivalent circuit model 43 (Figure 14(d)) and the electromagnetic simulation results of the dual-coil model 42 (Figure 14(b)), thereby determining the mutual inductance M in the dual-coil model 42. ab (906, Figure 21 For each distinct pair of coils in integrated layout 98, repeat steps 905 and 906 to determine the mutual inductance between each distinct pair of coils in integrated layout 38 (907, Figure 21 Therefore, when the circuit simulation results (Fig. 14(d)) of the equivalent circuit model 43 with coupling or mutual inductance are consistent with the electromagnetic simulation results (Fig. 14(b)), the mutual inductance M between the two coils is confirmed and solved. ab .

[0075] Optionally, a circuit verification model 44 can be created for two coil models 40, which includes the confirmed mutual inductance M in the dual-coil model 42 that can be created as shown in FIG14(e). abThen, for example, MATLAB can be used to perform circuit simulation on circuit verification model 44 to obtain results that can include Z. e The circuit simulation results of circuit verification model 44 (input impedance of circuit verification model 44). The mutual inductance M in model 44 can be verified by tuning the circuit. ab The circuit model 44 was optimized using MATLAB with capacitors and resistors to ensure that the circuit simulation results (Fig. 14(f)) best matched the circuit simulation results (Fig. 14(d)) of the dual-coil equivalent circuit model 43. Then, the mutual inductance M... ab The confirmed values ​​of capacitance and resistance are used to complete the equivalent circuit model of the two coils 43.

[0076] In exemplary method 90, the mutual inductance M between each different pair of coils in the already obtained integrated layout 38 ab Subsequently, an integrated layout equivalent circuit model 45 can be created, which includes the mutual inductance M between all different pairs of coil models in the integrated layout 38. ab ,like Figure 5 As shown. Circuit simulation was performed on the integrated layout equivalent circuit model 45 to obtain the circuit simulation results of the integrated layout equivalent circuit model 45. Figure 10 By tuning one or more of the inductance, resistance, and capacitance of one or more coil models 40 in the integrated layout equivalent circuit model 45, the circuit simulation results of the integrated layout equivalent circuit model 45 are improved. Figure 10 By optimally matching the circuit simulation results (e.g., input impedance) of the theoretical circuit 39, an optimized inductance (908, ) can be determined for each coil model 40 of each of the coils 31, 32, 33, and 34 in the integrated layout 38. Figure 21 ).

[0077] Based on its optimized inductance, the lengths of each coil 31, 32, 33, and 34 are recalculated using the aforementioned predetermined method. Then, based on the recalculated lengths of each coil 31, 32, 33, and 34, the integrated layout 38(99) of the multiple coils is redrawn. Figure 21 Optionally, method 90 may include creating a redrawn integrated layout model using electromagnetic simulation software, and performing electromagnetic simulation on the redrawn integrated layout physical model to obtain the electromagnetic simulation results of the redrawn integrated layout physical model. The electromagnetic simulation results of the redrawn integrated layout physical model can then be compared with the circuit simulation results of the theoretical circuit 39 to confirm the recalculated lengths of each coil 31, 32, 33, 34.

[0078] To produce the broadband electromagnetic sensor 10, the coil array structure 38(910, ...) of the sensing portion 20 is fabricated on the printed circuit board 50 according to a redrawn integrated layout. Figure 21Amplifier circuit 20 is also fabricated on printed circuit board 50 and connected to coil array structure 38 to form printed circuit board assembly 51. Notably, in coil array structure 38 comprising multiple coils 31, 32, 33, and 34, each coil has a different length than the others. In this way, each coil detects a signal having a frequency within its own frequency bandwidth, enabling the multiple coils 31, 32, 33, and 34 together to detect signals having frequencies within the frequency bandwidth of sensor 10.

[0079] To verify the operation of the broadband electromagnetic sensor 10 used for partial discharge detection, a device was fabricated as follows: Figure 15 The prototype shown has a sensing section 20 measuring 39.6mm × 52.6mm and is connected to the amplifier circuit 20 using a Sub-Miniature Version A (SMA) connector. The amplifier circuit 20 is added to increase the detection range of the antenna array and extend its range to power devices. The prototype therefore includes a broadband sensing section 30 and an amplifier circuit 20. Its structure is simple and cost-effective. The conceptual equivalent circuit model of this prototype includes a fourth-order inductor-capacitor resonant circuit, each consisting of an inductor and a capacitor connected in series or parallel.

[0080] In order to protect Figure 8 The printed circuit board assembly shown can be encapsulated in a plastic housing. In the manufactured experimental prototype, the package has dimensions of 12.5mm × 48mm × 100mm, as shown. Figure 16 As shown, it has an opening to allow the prototype to be placed and secured on the cable of the electrical equipment to be tested for partial discharge using releasable cable ties.

[0081] Use such as Figure 17 The experimental platform shown uses a prototype of the fabricated broadband electromagnetic sensor 10 to detect partial discharges. Sensor 10 is connected to an FPGA (Field-Programmable Gate Array) and placed near a high-voltage switchgear. Partial discharges from the high-voltage switchgear are detected by sensor 10, and the collected data is transmitted via the Internet to a back-end system for processing and display. The computer terminal of the back-end system displays the phase-resolved partial discharge (PRPD) of the high-voltage switchgear.

[0082] The sensitivity of the prototype sensor 10 was verified by changing its position relative to the partial discharge source. In tests using a calibrator as the partial discharge source with a 5pC voltage, the prototype sensor 10 was placed near the calibrator's cable, and the detected partial discharge was obtained and displayed on the oscilloscope screen. A commercial HFCT sensor was similarly placed around the cable and used to detect partial discharges from the calibrator. Compared to the commercial HFCT sensor, the prototype sensor yielded oscilloscope results with a similar pattern but a larger size, such as... Figure 18 As shown. When the prototype sensor 10 was placed 1 meter away from the electrical equipment used for detection, the prototype sensor 10 was still able to detect partial discharge, while the commercial HFCT sensor performed poorly. Table 1 below shows the results of tests conducted using the prototype sensor 10 and the commercial HFCT sensor when placed 1 meter away from voltage sources with different applied voltages.

[0083] Table 1

[0084]

[0085] like Figure 19 As shown, the prototype sensor 10 was also tested on an actual high-voltage device by attaching the unit of sensor 10 to multiple cables of the device. Figure 20 The results of the PRPD obtained by sensor 10 are shown in the figure. Experimental tests show that the broadband electromagnetic sensor 10, developed using the method described above 90 and comprising four planar coils and an additional capacitor, exhibits broadband characteristics and is able to detect partial discharge even at a distance from high-voltage equipment.

[0086] While exemplary embodiments of the invention have been described above, those skilled in the art will understand that many changes can be made to the details of design, construction, and / or operation without departing from the invention. However, it will be understood that many further changes, modifications, and substitutions can be made to various aspects of the embodiments within the spirit and scope of the appended claims. For example, although the coil array structure shown in the figures has a general rectangular shape, the coil array structure can have other configurations, such as circular, three-dimensional, or any other arbitrary shape.

[0087] Throughout this specification and the appended claims, unless the context otherwise requires, the word “comprising” and variations such as “including” or “containing” shall be construed as implying inclusion of the stated whole or group of wholes or steps, but not excluding any other whole or group of wholes. References to any existing publications (or information derived therefrom) or any known content in this specification are not and should not be construed as an acknowledgment or endorsement, or any form of implication, that existing publications (or information derived therefrom) or known content form part of common general knowledge in the field to which this specification pertains.

Claims

1. A method for producing a broadband electromagnetic sensor, the broadband electromagnetic sensor including an amplifier circuit connected to a sensing portion, the sensing portion including a coil array structure of a plurality of coils, wherein each coil is capable of detecting a signal having a frequency within its own frequency bandwidth, and wherein the coil array structure is capable of detecting a signal having a frequency within the frequency bandwidth of the broadband electromagnetic sensor, the method comprising the steps of: (a) The sensing portion is represented as a theoretical circuit, wherein each of the plurality of coils is represented by a theoretical inductor having a theoretical inductance, and a circuit simulation is performed on the theoretical circuit to obtain the circuit simulation result of the theoretical circuit and to obtain the theoretical inductance of each coil; (b) Calculate the length of each coil based on the theoretical inductance of each coil using a predetermined method, and draw an integrated layout of the plurality of coils based on the calculated length of each coil; (c) Use electromagnetic simulation software to create a coil model for each coil in the integrated layout, and perform electromagnetic simulation on the coil model to obtain the electromagnetic simulation results of the coil model; (d) Create a coil equivalent circuit model for each coil model, wherein each coil model is represented as an inductor connected in parallel with a capacitor and in series with a resistor, and perform circuit simulation on the coil equivalent circuit model to obtain the circuit simulation result of the coil equivalent circuit model, and determine the inductance, resistance and capacitance for each coil model when the circuit simulation result of the coil equivalent circuit model best matches the electromagnetic simulation result of the coil model; (e) Using the two coil models already created in step (c), create a dual-coil model of the two coils in the integrated layout, and perform an electromagnetic simulation on the dual-coil model to obtain the electromagnetic simulation results of the dual-coil model; (f) Using the two coil equivalent circuit models already created in step (d), a dual-coil equivalent circuit model of the dual-coil model is created, wherein the dual-coil equivalent circuit model includes the mutual inductance in the dual-coil model, and a circuit simulation is performed on the dual-coil equivalent circuit model to obtain the circuit simulation result of the dual-coil equivalent circuit model, and the mutual inductance in the dual-coil model is determined when the circuit simulation result of the dual-coil equivalent circuit model best matches the electromagnetic simulation result of the dual-coil model; (g) Repeat steps (e) and (f) for each different pair of coils in the integrated layout to determine the mutual inductance between each different pair of coils in the integrated layout; (h) Use all the coil equivalent circuit models created in step (d) to create an integrated layout equivalent circuit model, wherein the integrated layout equivalent circuit model includes the mutual inductance between each different pair of coils in the integrated layout, and perform circuit simulation on the integrated layout equivalent circuit model to obtain the circuit simulation results of the integrated layout equivalent circuit model, and determine the optimized inductance for each coil model when the circuit simulation results of the integrated layout equivalent circuit model best match the circuit simulation results of the theoretical circuit; (i) The length of each coil is recalculated based on the optimized inductance of each coil using the predetermined method, and the integrated layout of the plurality of coils is redrawn based on the recalculated length of each coil; as well as (j) The coil array structure is fabricated on a printed circuit board according to the redrawn integrated layout.

2. The method according to claim 1, wherein, The theoretical circuit in step (a) includes a stepped structure of a bandpass filter, wherein each element of the stepped structure includes one of the theoretical inductors electrically connected to a theoretical capacitor, and wherein each element is configured according to a preselected response type.

3. The method according to claim 2, wherein, The preselected response type is one of the following: Butterworth response, Chebyshev response, and elliptic response.

4. The method according to claim 1, further comprising: Immediately after step (h), a circuit verification model of the two coils, including the confirmed mutual inductance between the two coils, is created, and a circuit simulation is performed on the circuit verification model to obtain the circuit simulation result of the circuit verification model, wherein the matching of the circuit simulation result of the circuit verification model with the circuit simulation result of the dual-coil equivalent circuit model confirms the mutual inductance between the two coils.

5. The method according to claim 4, wherein, The circuit verification model of the integrated layout includes a T-type circuit.

6. The method according to claim 1, wherein, The electromagnetic simulation results and the circuit simulation results include the changes in input impedance and scattering parameters with frequency.

7. The method according to claim 1, further comprising: The amplifier circuit is fabricated on the printed circuit board and connected to the coil array structure.

8. The method according to claim 1, further comprising: After step (i), the electromagnetic simulation software is used to create a redrawn integrated layout model of the redrawn integrated layout, electromagnetic simulation is performed on the redrawn integrated layout physical model to obtain the electromagnetic simulation results of the redrawn integrated layout physical model, and the electromagnetic simulation results of the redrawn integrated layout physical model are compared with the circuit simulation results of the theoretical circuit to confirm the length of each recalculated coil.

9. A broadband electromagnetic sensor, comprising: An amplifier circuit that has a gain of at least 26 dB through its bandwidth; as well as The sensing section includes a coil array structure of multiple coils, wherein each of the multiple coils has a different length from the other coils, and each coil detects a signal having a frequency within its own frequency bandwidth, such that the multiple coils together can detect a signal having a frequency within the frequency bandwidth of the sensor, and wherein the frequency bandwidth of the sensor ranges from about 1 MHz to 100 MHz, such that the sensor can detect partial discharge from the high-voltage equipment without physical contact with the high-voltage equipment. The coil array structure is configured as an integrated layout on a printed circuit board, the sensing portion can be represented as a theoretical circuit, each of the plurality of coils is represented by a theoretical inductor with theoretical inductance, the equivalent circuit model of the integrated layout includes the mutual inductance between each different pair of coils in the integrated layout, the mutual inductance is determined to be optimized when the circuit simulation result of the equivalent circuit model best matches the circuit simulation result of the theoretical circuit, and the length of each coil is calculated based on the optimized inductance of each coil.

10. The broadband electromagnetic sensor according to claim 9, wherein, The integrated layout is optimized to minimize the area required by the printed circuit board to support the coil.

11. The broadband electromagnetic sensor according to claim 9, wherein, Each coil can be represented by an equivalent circuit model, which includes a capacitor connected in parallel with the inductor and the inductor connected in series with a resistor.

12. The broadband electromagnetic sensor according to claim 9, wherein, The coil array structure includes one of the following: rectangular shape, circular shape, or three-dimensional structure.

Images