Electronic detonator communication signal receiving method, system and circuit

Abstract

The application relates to the technical field of digital electronic detonator communication, in particular to an electronic detonator communication signal receiving method, system and circuit; the method comprises the following steps: making a bus flow through a communication current; generating a first magnetic flux FA in a first coil and a second magnetic flux FB in a second coil through the communication current, wherein the number of turns of the first coil and the second coil is the same and the winding directions are opposite, and the first magnetic flux FA and the second magnetic flux FB are equal in size under the same communication current; the application realizes high-sensitivity receiving of the communication signal through a double-magnetic-core differential coupling structure and is not limited by the sampling resistance value. Experiments show that, under the same communication current change rate, the signal voltage amplitude of the application is 5 to 10 times that of the prior art, and the technical problem of insufficient signal receiving sensitivity caused by the limited sampling resistance value in the prior art is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of digital electronic detonator communication technology, specifically to an electronic detonator communication signal receiving method, system, and circuit. Background Technology

[0002] Digital electronic detonators, as an advanced detonating device, have been widely used in fields such as mining blasting, tunnel excavation, and seismic exploration. Compared with traditional electric detonators, digital electronic detonators have advantages such as high delay accuracy, programmable control, and good safety. The core of their advantages lies in the two-way communication between the detonator and the digital electronic detonator.

[0003] In existing digital electronic detonator communication schemes, the detonator supplies power to the digital electronic detonator and achieves communication functionality via an H-bridge circuit. The H-bridge circuit has two outputs, bus 1 and bus 2, connected to the digital electronic detonator. A sampling resistor is connected in series on each bus, and an amplifier circuit is connected across the sampling resistor. When the digital electronic detonator sends data to the detonator, it modulates the information by controlling the magnitude of the communication current flowing through it. The sampling resistor converts the communication current into a voltage signal, which is then amplified by the amplifier circuit. The detonator then decodes this voltage signal to obtain the data sent by the digital electronic detonator.

[0004] However, the aforementioned existing technical solutions have the following significant drawbacks: Bus 1 and Bus 2 serve as both signal paths and power supply paths for the digital electronic detonator during communication, sharing the same physical channel. While using a larger sampling resistor can achieve a higher amplification factor, it will interfere with the power supply to the digital electronic detonator, potentially leading to malfunctions. To prevent the sampling resistor from significantly affecting the power supply, its value needs to be significantly smaller than the bus resistor, typically between 10 and 20 ohms. This limitation severely restricts the detonator's ability to amplify communication current signals, hindering high-sensitivity signal reception. Furthermore, the sampling amplification circuit in the existing technology uses a single-ended signal amplification method, lacking effective suppression of common-mode interference. When electromagnetic interference is present in the environment, the interference signal will be amplified, leading to increased communication error rate and decreased reliability. Summary of the Invention

[0005] This disclosure presents a method, system, and circuit for receiving communication signals from electronic detonators, with the aim of overcoming at least one of the defects existing in the prior art.

[0006] To achieve the above objectives, the technical solution disclosed in this invention is as follows: According to one aspect of this disclosure, a method for receiving communication signals from an electronic detonator is provided, characterized by comprising the following steps: Allow communication current to flow through the bus; The communication current generates a first magnetic flux ΦA in the first coil and a second magnetic flux ΦB in the second coil, wherein the first coil and the second coil have the same number of turns and are wound in opposite directions, for generating the first magnetic flux ΦA and the second magnetic flux ΦB of equal magnitude under the same communication current; The first magnetic flux ΦA and the second magnetic flux ΦB are made to pass through the signal coil in the same direction, thus combining to form a total magnetic flux: Φ 总 =ΦA+ΦB; Make the total magnetic flux Φ 总 Excite signal voltage U in the signal coil 信号 =-N×(dΦ 总 / dt), where N is the number of turns of the signal coil; The signal voltage is acquired and amplified to obtain the useful signal corresponding to the communication current.

[0007] Furthermore, when common-mode interference current appears in the bus: For the first coil, the direction of the first common-mode magnetic flux ΦA' generated by the common-mode interference current is opposite to the direction of the first magnetic flux ΦA; For the second coil, the direction of the second common-mode magnetic flux ΦB' generated by the common-mode interference current is the same as the direction of the second magnetic flux ΦB; The first common-mode magnetic flux ΦA' and the second common-mode magnetic flux ΦB' are reversed and passed through the signal coil to synthesize a total magnetic flux Φ. 总' =ΦA'-ΦB'=0; A constant magnetic flux does not generate voltage, thereby suppressing the common-mode interference.

[0008] Furthermore, the first coil and the second coil have the same number of turns, but are wound in opposite directions, thereby generating a first magnetic flux ΦA and a second magnetic flux ΦB of equal magnitude under the same communication current.

[0009] Furthermore, both the first and second magnetic cores are toroidal magnetic cores, and there is an air gap at the joint of the two toroidal magnetic cores, with the magnetic circuits of the two magnetic cores being independent of each other.

[0010] Furthermore, when the bus is supplying power to the digital electronic detonator, the current in the circuit is constant, and the only obstacle to the current in the signal receiving circuit is the resistance in the coil.

[0011] Furthermore, the amplification factor of the communication current signal is increased by increasing the number of turns N of the signal coil, while keeping the number of turns of the first coil and the second coil unchanged, in order to suppress the influence on the power supply of the digital electronic detonator.

[0012] Furthermore, the steps of acquiring and amplifying the signal voltage specifically include: connecting the two ends of the signal coil to the input port of the differential amplifier circuit; performing differential amplification processing on the signal voltage through the differential amplifier circuit; and outputting the amplified voltage signal to the decoding circuit for information decoding.

[0013] Furthermore, it also includes a filter circuit connected in series between the signal coil and the amplifier circuit to filter out high-frequency noise.

[0014] According to another aspect of this disclosure, an electronic detonator communication signal receiving system is provided for implementing the electronic detonator communication signal receiving method described above, comprising: A dual-core coupling module includes a first core and a second core. A first coil is wound on the first core, and a second coil is wound on the second core. The first coil and the second coil have the same number of turns but are wound in opposite directions. A signal coil is disposed at the contact point between the first magnetic core and the second magnetic core, and is used to receive the magnetic flux signal after differential coupling and to excite the signal voltage; An amplifier circuit module, connected to the signal coil, is used to acquire and amplify the signal voltage U excited by the signal coil. 信号 =-N×(dΦ 总 / dt); A decoding module, connected to the amplifier circuit module, is used to decode the amplified voltage signal into data information; When the digital electronic detonator sends information to the detonator, the communication current in the bus generates a first magnetic flux ΦA and a second magnetic flux ΦB of equal magnitude in the first coil and the second coil, respectively. The magnetic flux signal is synthesized by the signal coil and then collected and amplified in the amplifier circuit module. Finally, the information is decoded by the decoding module.

[0015] According to another aspect of this disclosure, an electronic detonator communication signal receiving circuit is provided, comprising: Both the first and second magnetic cores are ring structures and are fitted together, with an air gap at the fitting point. The first coil is wound on the first magnetic core and connected to the first bus. The second coil is wound on the second magnetic core and connected to the second bus. The first coil and the second coil have the same number of turns but are wound in opposite directions. A signal coil is wound around the joint between the first magnetic core and the second magnetic core; The differential amplifier circuit has its input terminal connected to both ends of the signal coil. The communication current generates a first magnetic flux ΦA in the first coil and a second magnetic flux ΦB in the second coil. ΦA and ΦB pass through the signal coil in the same direction to combine into a total magnetic flux. Φ 总 =ΦA+ΦB, Excitation signal voltage U 信号 =-N×(dΦ 总 / dt); When common-mode interference occurs, the total magnetic flux Φ is synthesized. 总' =ΦA'-ΦB'=0, used for common-mode interference suppression.

[0016] The beneficial effects of this invention are: This invention achieves high-sensitivity reception of communication signals through a dual-core differential coupling structure, unaffected by the value of the sampling resistor. Because coils A and B have the same number of turns and the same communication current, ΦA and ΦB are of the same magnitude. ΦA and ΦB pass through the signal coil in the same direction, and the total magnetic flux Φ in the signal coil is... 总 =ΦA+ΦB, the total magnetic flux Φ always generates a signal voltage U in the signal coil. 信号 =-N×(dΦ 总 Since the number of turns N of the signal coil can be increased independently, compared with the prior art which is limited by the value of the sampling resistor, the present invention can achieve higher signal receiving sensitivity. Experiments show that, under the same rate of change of communication current, the signal voltage amplitude of the present invention is 5 to 10 times that of the prior art, effectively solving the technical problem of insufficient signal receiving sensitivity caused by the limited value of the sampling resistor in the prior art.

[0017] Furthermore, the principle of reverse magnetic flux superposition effectively suppresses common-mode interference and improves communication reliability. When common-mode interference current appears in the bus, because coils A and B have the same number of turns, the common-mode current flowing through them is the same, therefore ΦA and ΦB are of the same magnitude. ΦA and ΦB flow through the receiving coil in opposite directions, and the total magnetic flux Φ in the receiving coil... 总 =ΦA-ΦB=0. A constant magnetic flux does not induce voltage, and common-mode interference is completely suppressed. The common-mode rejection ratio of this invention reaches over 60 dB across the entire operating frequency range, significantly better than the traditional single-ended sampling scheme by approximately 20 dB. In the strong electromagnetic interference environment of a mine blasting site, the communication error rate of traditional schemes is as high as 10%. -3 Up to 10 -2 The communication error rate of the present invention is less than 10%. -9 The reliability has been improved by more than three orders of magnitude, effectively solving the technical problem that single-ended sampling amplifier circuits in the prior art lack common-mode interference suppression capability.

[0018] Furthermore, increasing the amplification factor by increasing the number of turns in the signal coil does not affect the power supply to the digital electronic detonator, thus achieving a balance between signal amplification capability and power supply reliability. To increase the amplification factor for current signals, the number of turns in the signal coil can be increased, thereby increasing the turns ratio of the signal receiving coil to coil A and coil B. Since coil A and coil B remain unchanged, there is no impact on the power supply. This invention allows for flexible adjustment of signal receiving sensitivity to adapt to the needs of different application scenarios without affecting the power supply, effectively resolving the technical contradiction between signal amplification capability and power supply reliability in existing technologies.

[0019] Furthermore, the differential magnetic coupling structure is simple, reliable, and easy to integrate into existing detonator systems. Compared with traditional solutions that require additional common-mode filters, isolation transformers, and other auxiliary equipment, this invention can achieve efficient common-mode suppression solely through the dual-core differential coupling structure itself, eliminating the need for additional auxiliary devices. This simplifies system design, reduces costs and failure rates, while the magnetic circuit isolation design also improves the electrical safety performance of the system.

[0020] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a dual-core differential coupling structure. Figure 2 The simulation results of magnetic flux coupling and induced voltage of communication signals are shown in Figure (a), where sub-figure (b) is the pulse sequence of communication current I, sub-figure (c) is the time-domain waveform of total magnetic flux, and sub-figure (d) is the time-domain waveform of induced voltage. Figure 3 This is a schematic diagram illustrating the common-mode interference suppression effect of differential magnetic coupling. Figure 4 The diagram shows the timing and waveform processing effects of the communication signal. Sub-figure (a) is the communication current pulse sequence, sub-figure (b) is the time-domain waveform of the magnetic coupling induced voltage, and sub-figure (c) is the decoded signal after amplification and filtering. Figure 5 This is a simulation diagram illustrating the relationship between signal amplification factor and the number of coil turns. Figure 6 A simulation diagram of the signal reception effect of an electronic detonator communication system; Figure 7 This is a schematic diagram of the dual-core differential coupling structure of the present invention; Figure 8 This is a schematic diagram of the circuit structure of the present invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0023] The term "comprising," and any variations thereof, used in the specification and claims of this application, is intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or apparatus. Furthermore, the use of "and / or" in the specification and claims indicates at least one of the connected objects, such as A and / or B, indicating the inclusion of A alone, B alone, or both A and B.

[0024] In embodiments of the present invention, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Rather, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0025] The present invention provides the following preferred embodiments: In one embodiment, reference Figure 1 As shown, the electronic detonator communication signal receiving method of the present invention includes the following steps: S100 allows communication current to flow through the bus. When the detonator sends a communication signal to the digital electronic detonator, it drives current in bus 1 and bus 2 through the H-bridge circuit. The H-bridge circuit is a classic four-arm power switching topology that can generate a variable polarity driving voltage across the bus. By controlling the on / off state of the four arm power devices, it can achieve forward power supply, reverse power supply, or high impedance state for the digital electronic detonator. During communication, the H-bridge operates in a specific switching state, allowing a communication current with controlled amplitude to flow through the bus. The digital electronic detonator modulates information by controlling the magnitude of the communication current flowing through it. The change in this communication current corresponds to the digital data that the digital electronic detonator needs to send. Specifically, when the digital electronic detonator needs to send the digit 1, it increases the communication current to jump from the idle value I0 to the desired value I1; when it needs to send the digit 0, it decreases the communication current to fall back from the desired value I1 to the idle value I0. The waveform of the communication current is usually a rectangular pulse sequence, and its duty cycle and frequency are determined according to the specific communication protocol. In this embodiment, it is assumed that the communication current varies from 10 mA to 30 mA, corresponding to different digital states. The idle current I0 is 10 mA, and the desired current I1 is 30 mA. The communication protocol adopts the NRZ encoding format, with each bit lasting 100 microseconds and a transmission rate of 10 kilobits per second. Under this protocol, the digital electronic detonator controls the internal current regulator to make the bus current jump between I0 and I1. The transition edge carries bit synchronization information, and the detonator realizes clock recovery and data decision by detecting the current transition edge.

[0026] S200, the communication current generates a first magnetic flux ΦA in the first coil and a second magnetic flux ΦB in the second coil, wherein the first coil and the second coil have the same number of turns and are wound in opposite directions. Both magnetic cores are toroidal cores with identical specifications. An air gap exists at the joint of the two magnetic cores, making their magnetic circuits independent. The toroidal cores are made of a soft magnetic material with high permeability; in this embodiment, manganese-zinc ferrite material is selected, with an initial permeability of approximately 2500, stable relative permeability at low frequencies, and a low loss factor, making it suitable for signal coupling applications. The two magnetic cores have the same dimensions: an outer diameter of 15 mm, an inner diameter of 8 mm, and a height of 4 mm. The first coil is wound on the first magnetic core. Bus 1 passes through the central hole of the first magnetic core and winds around the outer periphery of the core, forming coil A with 10 turns, wound in a clockwise direction (viewed from the top of the magnetic core). The second coil is wound on the second magnetic core. Bus 2 passes through the central hole of the second magnetic core and winds around the outer periphery of the core, forming coil B with 10 turns, wound in a counterclockwise direction (viewed from the bottom of the magnetic core), opposite to coil A. When the communication current flows into coil A from bus 1, the current flows in from the left side and out from the right side, generating a first counterclockwise magnetic flux ΦA in magnetic core A. When the communication current flows into coil B from bus 2, the current flows in from the right side and out from the left side, generating a second clockwise magnetic flux ΦB in magnetic core B. Since the two coils have the same number of turns and the same communication current, ΦA and ΦB are equal in magnitude and both proportional to the communication current. In this embodiment, when the communication current is 20 mA, the magnetic flux generated by each coil is approximately 0.8 microWebers.

[0027] S300, the first magnetic flux ΦA and the second magnetic flux ΦB pass through the signal coil in the same direction, combining the total magnetic flux Φ 总 =ΦA + ΦB. The signal coil is wound at the junction of the lower part of magnetic core A and the upper part of magnetic core B, i.e., on the common boundary of the two magnetic cores. The signal coil is wound circumferentially around the magnetic cores, with 100 turns. Since the currents in the two coils are in opposite directions, the magnetic fluxes they produce in their respective magnetic cores are in opposite directions. However, due to the air gap design at the junction of the two magnetic cores, the magnetic circuits of the two magnetic cores are independent, and there is no closed shared magnetic circuit. Importantly, because the winding directions of coils A and B are opposite, and the magnetic circuits of the two magnetic cores are independent, when the current flows into the two coils from opposite directions, the two magnetic fluxes actually pass through their respective magnetic cores from opposite directions, but ultimately both pass through the signal coil at the junction, and in the same direction. Therefore, the total magnetic flux in the signal coil is the algebraic sum of ΦA and ΦB, i.e., Φ = ΦA + ΦB. 总 =ΦA+ΦB. This differential coupling design is the core innovation of this invention: two coil currents in opposite directions generate two magnetic flux signals in the same direction, making the total magnetic flux in the signal coil twice that of a single magnetic core, thus significantly improving the sensitivity of signal reception.

[0028] S400, causing the total magnetic flux Φ to always generate a signal voltage U in the signal coil. 信号 =-N×(dΦ 总 / dt), where N is the number of turns in the signal coil. According to Faraday's law of electromagnetic induction, the rate of change of magnetic flux in a closed coil is proportional to the induced voltage, and the proportionality constant is the negative of the number of turns N. When the communication current changes, the magnetic flux in magnetic cores A and B changes accordingly, and the rate of change is proportional to the rate of change of the communication current. Since Φ 总 =ΦA+ΦB, and both ΦA and ΦB are proportional to the communication current. Therefore, the signal voltage Usignal = -N×(dΦ) 总 The flux change rate (dI / dt) is proportional to the rate of change of the communication current (dI / dt), with a proportionality constant of N multiplied by the core coupling coefficient. When the communication current jumps from I0 to I1 at a rate of 10 mA per microsecond, the flux change rate is also 10 mA per microsecond. Multiplying this by the core coupling coefficient and the number of turns N=100, the signal voltage can reach the order of hundreds of millivolts to several volts. In this embodiment, assuming that the core coupling coefficient causes every 1 mA change in communication current to generate an induced voltage of 0.1 millivolts in the signal coil, then when the current jumps by 30 mA, the peak signal voltage is approximately 3 millivolts, which can reach the order of volts after amplification.

[0029] S500 acquires and amplifies the signal voltage to obtain the useful signal corresponding to the communication current. The two ends of the signal coil are connected to the input port of a differential amplifier circuit to acquire and amplify the signal voltage. The differential amplifier circuit uses a low-noise operational amplifier configured as a high-gain differential amplifier with a magnification factor of approximately 100, capable of amplifying the millivolt-level induced voltage to the volt level. The amplified voltage signal is output to the decoding circuit. The decoding circuit first converts the analog signal into a digital signal using a comparator. The comparator's decision threshold is set to 50% of the signal amplitude; when the signal voltage is higher than the threshold, it is judged as a digital 1, and when it is lower, it is judged as a digital 0. Then, the digital signal is sampled and judged according to the communication protocol to recover the original data sequence. The entire signal reception process completes the complete signal chain from current modulation to voltage demodulation. Due to the use of a differential magnetic coupling structure, the signal coil is independent of the bus coil and does not participate in the power supply circuit, thus avoiding interference with the power supply and achieving high-sensitivity signal reception.

[0030] In one embodiment, reference Figure 2 As shown, a detailed analysis of the quantitative relationship between magnetic flux coupling and induced voltage of communication signals is presented.

[0031] The relationship between the magnetic flux ΦA generated by the communication current in the first coil and the magnetic flux ΦB generated by the communication current in the second coil, and the communication current itself, is determined by the magnetic properties of the magnetic core. In this embodiment, it is assumed that the magnetic core is made of manganese-zinc ferrite material, whose permeability is approximately constant at low magnetic flux density. When the communication current flows through the first coil, it generates the first magnetic flux ΦA; when the communication current flows through the second coil, it generates the second magnetic flux ΦB. Since coils A and B have the same number of turns and the same communication current, ΦA and ΦB are the same in magnitude. Specifically, the relationship is: ΦA = ΦB = Λ × N_base × I, where Λ is the permeability, N_base is the number of turns of coil A or coil B, and I is the communication current.

[0032] refer to Figure 2 The simulation results provide a quantitative analysis of the magnetic flux coupling process. Assume that coils A and B have N_base = 10 turns, and the communication current jumps from an idle value I0 = 10 mA to a desired value I1 = 30 mA, then ΔI = 20 mA. Assume that the magnetic permeability Λ induces a 0.1 mV voltage in the signal coil for every 1 mA change in communication current. Then, when the current jumps, ΦA and ΦB each change by ΔΦA = ΔΦB. Because ΦA and ΦB pass through the signal coil in the same direction, the total change in magnetic flux ΔΦ 总 =ΔΦA + ΔΦB. Assuming the signal coil has N = 100 turns, then the induced voltage U... 信号 =-N×(dΦ 总 Assuming the current switching time Δt = 2 microseconds, then dI / dt = ΔI / Δt = 10 mA per microsecond, and the peak signal voltage is approximately U signal = 200 millivolts.

[0033] Figure 2 Subplot (a) shows the pulse sequence as the communication current I jumps from 10 mA to 30 mA, with the horizontal axis representing time (µs) and the vertical axis representing current (mA). Subplot (b) shows Φ 总 The time-domain waveform is ΦA + ΦB. When the current jumps from I0 to I1, ΦA and ΦB increase synchronously, and Φ_total equals the sum of ΦA and ΦB. 总 The peak value is approximately twice that of ΦA or ΦB. When the current drops back from I1 to I0, ΦA and ΦB decrease simultaneously, and the total Φ decreases simultaneously as well. This verifies that Φ... 总 =ΦA+ΦB differential superposition principle. Sub-figure (c) shows the induced voltage U 信号 =-N×(dΦ 总 The time-domain waveform is shown in the figure ( / dt). The induced voltage generates a spike pulse when the current changes; a positive spike corresponds to the current rising process, and a negative spike corresponds to the current falling process. The timing of the spike pulse corresponds precisely to the current rising edge and carries position synchronization information.

[0034] In one embodiment, reference Figure 7 and Figure 8As shown, the dual-core differential coupling structure of the present invention will be described in detail.

[0035] Figure 7 and Figure 8 The electrical principles and structural circuit diagrams of this invention are illustrated. For example... Figure 8 As shown, this invention uses two identical toroidal magnetic cores stacked together, with core A on top and core B below. Both cores are made of manganese-zinc ferrite material, with identical dimensions: an outer diameter of 15 mm, an inner diameter of 8 mm, and a height of 4 mm. Bus 1 is wound around the upper end of core A, forming coil A with 10 turns, wound clockwise. Bus 2 is wound around the lower end of core B, forming coil B with 10 turns, wound counterclockwise, opposite to coil A. The lower part of core A and the upper part of core B are attached together, together winding a signal coil with 100 turns. The two ends of the signal coil are connected to the input port of the amplifier circuit. The current signal in bus 1 is coupled to the signal coil through core A; the current signal in bus 2 is coupled to the signal coil through core B. Because of the air gap (separated by a non-magnetic material spacer, approximately 0.1 mm thick) at the joint of magnetic cores A and B, the magnetic circuits of the two cores are independent of each other. Therefore, the magnetic flux generated by the current signal in bus 1 will not directly interfere with bus 2, and vice versa. This independence of the magnetic circuit is the technical basis for achieving differential coupling and common-mode rejection.

[0036] The working principle of the dual-core differential coupling module is as follows: When the digital electronic detonator sends information to the detonator, a communication current flows in the bus. For core A, this current flows in from the left side and out from the right side, generating a counterclockwise magnetic flux ΦA; for core B, this current flows in from the right side and out from the left side, generating a clockwise magnetic flux ΦB. Because coils A and B have the same number of turns and the same communication current, ΦA and ΦB are the same. ΦA and ΦB flow in the same direction through the signal coil, and the total magnetic flux Φ in the signal coil is... 总 =ΦA+ΦB. The total magnetic flux induces a signal voltage U in the signal coil. 信号 =-N×(dΦ 总 / dt), this voltage is collected and amplified by the amplifier circuit to obtain the communication current signal in the bus.

[0037] When common-mode interference occurs in the bus, assume the common-mode current flows from the detonator end to the initiator end. For coil B, the direction of the current flowing in remains unchanged, and the direction of the generated magnetic flux ΦB also remains unchanged. For coil A, the direction of the current flowing in changes, and the direction of the generated magnetic flux ΦA also changes accordingly, becoming clockwise. Because coils A and B have the same number of turns and the same common-mode current flowing through them, ΦA and ΦB are of the same magnitude. ΦA and ΦB flow in opposite directions through the signal coil, receiving the total magnetic flux Φ in the receiving coil. 总 =ΦA-ΦB=0. A constant magnetic flux does not generate voltage, thus suppressing common-mode interference.

[0038] The structure of this invention differs significantly from existing technologies in the following ways: First, magnetic isolation between the signal path and the power supply path is achieved through a dual-core differential coupling structure, eliminating the sampling resistor as a limiting factor. Second, active suppression of common-mode interference is achieved through the differential magnetic coupling principle, rather than passive filtering. Third, increasing the number of turns in the signal coil improves the amplification factor without affecting power supply quality, as the signal coil is not connected in series in the power supply circuit. These structural innovations make this invention significantly superior to existing technologies in terms of signal reception sensitivity and anti-interference capability.

[0039] In one embodiment, reference Figure 3 As shown, the principle and effect of common-mode interference suppression of the present invention will be described in detail.

[0040] Common-mode interference is a significant factor affecting the reliability of electronic detonator communication. At mining blasting sites, numerous high-power electrical devices exist, such as hoists, conveyors, and crushers. These devices generate strong transient electromagnetic interference during startup and shutdown. Furthermore, wireless transmitting equipment such as communication base stations and broadcast television towers also generate high-frequency electromagnetic fields around the bus. These interference signals couple to bus 1 and bus 2 through distributed capacitance or inductance, forming common-mode interference currents. Traditional single-ended sampling amplifier circuits have only one signal input and cannot distinguish between common-mode interference and the useful signal; the interference signal is amplified along with the signal, leading to an increased communication error rate. In extreme cases, strong common-mode interference may even overwhelm the useful signal, causing complete communication failure.

[0041] This invention effectively suppresses common-mode interference through a differential magnetic coupling structure. Its working principle is based on the principle of magnetic flux superposition. When a common-mode interference current appears in the bus, it is assumed that the direction of the common-mode current is from the digital electronic detonator end to the initiator end. For coil B, the current flows in from its right side and out from its left side, consistent with the current direction during normal communication. Therefore, the direction of the second common-mode magnetic flux ΦB' generated in magnetic core B is the same as the direction of the second magnetic flux ΦB during normal operation. For coil A, the current flows in from its right side and out from its left side, opposite to the direction during normal communication (where the current flows in from the left side and out from the right side). Therefore, the direction of the first common-mode magnetic flux ΦA' generated in magnetic core A is opposite to the direction of the first magnetic flux ΦA during normal operation.

[0042] Since coils A and B have the same number of turns and the same common-mode interference current, the magnitudes of the first common-mode magnetic flux ΦA' and the second common-mode magnetic flux ΦB' are equal. In the signal coil, the paths of ΦA' and ΦB' are opposite, resulting in a total magnetic flux Φ 总'=ΦA'-ΦB'=0. According to Faraday's law of electromagnetic induction, the induced voltage is proportional to the rate of change of magnetic flux. When the magnetic flux is constant at zero, no induced voltage is generated. Therefore, common-mode interference will not generate any induced voltage in the signal coil and is thus completely suppressed.

[0043] from Figure 3 The simulation results show that the common-mode rejection ratio (CMRR) of the proposed solution is significantly better than that of the single-ended sampling solution across the entire operating frequency range. In the figure, the horizontal axis represents the signal frequency, and the vertical axis represents the CMRR, in decibels (dB). The solid line represents the CMRR curve of the proposed solution, and the dashed line represents the CMRR curve of the traditional single-ended sampling solution. It is clearly visible from the figure that in the low-frequency range of 100 Hz to 1 kHz, the CMRR of the proposed solution reaches over 80 dB, significantly better than the approximately 20 dB level of the traditional solution. As the frequency increases, both curves decrease, but the proposed solution maintains a suppression advantage of approximately 20 dB throughout the entire measurement frequency band. Specifically, at 10 kHz, the CMRR of the proposed solution is approximately 70 dB, while the traditional solution is approximately 50 dB; at 100 kHz, the proposed solution is approximately 55 dB, while the traditional solution is approximately 35 dB; and at 1 MHz, the proposed solution is approximately 40 dB, while the traditional solution is approximately 20 dB. This result demonstrates that the differential magnetic coupling structure can effectively suppress common-mode interference over a wide frequency range, significantly improving communication reliability and anti-interference capability.

[0044] Improving common-mode rejection is crucial for applications in complex electromagnetic environments. In mine blasting sites, numerous high-power electrical devices, radio communication equipment, and transient electromagnetic pulses exist, generating strong common-mode interference. Traditional single-ended sampling schemes have limited common-mode rejection capabilities, often requiring additional common-mode filters, shielded cables, and isolation transformers to ensure communication reliability. This increases system complexity, cost, and failure rate. The solution presented in this invention eliminates the need for additional common-mode filters; the magnetic coupling structure itself achieves highly efficient common-mode rejection, simplifying system design, reducing costs, and improving reliability.

[0045] In one embodiment, reference Figure 4 As shown, the timing waveform processing and decoding process of communication signals is explained in detail.

[0046] When a digital electronic detonator sends data to the detonator, it modulates the information by controlling the magnitude of the communication current. This embodiment uses current amplitude modulation, with the following specific protocol: the desired current is set to I1 = 30 mA, corresponding to the digit 1; the idle current is set to I0 = 10 mA, corresponding to the digit 0. When the digit 1 needs to be sent, the detonator control circuit increases the communication current to I1; when the digit 0 needs to be sent, the detonator control circuit decreases the communication current to I0. The transition edge of the communication current carries bit synchronization information, and the detonator uses the detection of the current transition edge to achieve clock recovery and data decision-making. In this protocol, each bit lasts for 100 microseconds, i.e., the transmission rate is 10 kilobits per second. Data transmission uses LSB-first bit order, i.e., the least significant bit is sent first, followed by the most significant bit. Each data frame contains 8 bits, corresponding to the transmission of one byte. The frame structure includes a start bit (fixed to the number 1, lasting 100 microseconds), data bits (8 bits, variable), parity bit (odd parity bit, lasting 100 microseconds), and stop bit (fixed to the number 1, lasting 100 microseconds), with a total frame length of 1.1 milliseconds.

[0047] Figure 4 Subgraph (a) shows the timing waveform of the communication current. The horizontal axis represents time in microseconds, and the vertical axis represents current in milliamperes. As can be seen from the figure, the current jumps between I0 = 10 mA and I1 = 30 mA, forming a rectangular pulse sequence. At time t1, the current jumps from I0 to I1, corresponding to the start of the digit 1; at time t2, the current jumps from I1 to I0, corresponding to the end of the digit 1. The time interval between two adjacent transition edges corresponds to the duration of one data bit, i.e., 100 microseconds. The edge position and duration of the data can be clearly identified from the timing waveform, thereby extracting the digital information. In this embodiment, the data bit duration is set to 100 microseconds, i.e., the transmission rate is 10 kilobits per second, which meets the real-time requirements of digital electronic detonator communication.

[0048] When the communication current changes, the magnetic flux in cores A and B changes accordingly. According to Faraday's law of electromagnetic induction, the change in magnetic flux induces a voltage U signal = -N × (dΦtotal / dt) in the signal coil, and the induced voltage is proportional to the rate of change of current. As can be seen from sub-figure (b), the waveform of the induced voltage is a sequence of spike pulses, the amplitude of which is proportional to the rate of change of communication current. When the current rises from I0 to I1, the magnetic flux increases, and the induced voltage is a positive spike, the peak value of which depends on the current jump amplitude and the core coupling coefficient; when the current falls from I1 to I0, the magnetic flux decreases, and the induced voltage is a negative spike. The timing of the spike pulses precisely corresponds to the current jump edge, carrying bit synchronization information. Because the induced voltage is proportional to the rate of change of current rather than the current amplitude, the signal edges are enhanced, while DC and low-frequency components are suppressed. This characteristic naturally has a high-pass filtering effect, which can remove low-frequency noise and DC drift.

[0049] After the induced voltage signal is amplified by the differential amplifier circuit, the result is as follows: Figure 4 The amplified signal is shown in sub-figure (c). The amplification circuit uses a low-noise, high-bandwidth operational amplifier TL072, configured as a differential amplifier with a gain of 200, capable of amplifying millivolt-level induced voltage to the volt level. The amplified signal first passes through a low-pass filter to remove high-frequency noise, and then is sent to a comparator for digitization. The comparator's decision threshold is set to 50% of the signal amplitude; when the signal voltage is higher than the threshold, it is judged as a digital 1, and when it is lower than the threshold, it is judged as a digital 0. The digitized signal is sent to the decoding circuit, where it is sampled and judged according to the communication protocol to recover the original data sequence. The decoding process includes clock recovery, data sampling, odd parity checking, and stop bit detection; any error in any step will trigger a retransmission mechanism. Figure 4 As shown in sub-figure (c), the amplified and filtered signal waveform is clear with steep edges, facilitating digital decision-making. The entire signal processing link exhibits excellent anti-interference performance, enabling reliable communication tasks to be completed in environments with strong electromagnetic interference.

[0050] In one embodiment, reference Figure 5 As shown, a simulation analysis is performed to examine the relationship between signal amplification factor and the number of coil turns.

[0051] Signal reception sensitivity is an important indicator for evaluating the performance of a communication system. In this invention, the signal voltage U... 信号 =-N×(dΦ 总 The signal voltage amplitude is dI / dt, where N is the number of turns in the signal coil. Therefore, increasing the number of turns N in the signal coil directly increases the signal voltage amplitude, thereby improving receiver sensitivity. On the other hand, the signal voltage is also proportional to the rate of change of the communication current, dI / dt; the greater the rate of change, the greater the signal voltage. In practical applications, the rate of change of the communication current is limited by the driving capability of the detonator's internal circuitry and the bus impedance, and usually has an upper limit. Therefore, given a certain rate of change of current, increasing the number of turns N in the signal coil to increase the signal voltage amplitude is the most direct and effective method to improve receiver sensitivity.

[0052] Figure 5 The simulation results show the relationship between signal voltage amplitude and the number of turns in the signal coil. The horizontal axis represents the number of turns N in the signal coil (in turns), and the vertical axis represents the signal voltage amplitude (in millivolts). The three curves correspond to three different rates of change of communication current: curve A corresponds to di / dt = 5 mA / µs, curve B corresponds to di / dt = 10 mA / µs, and curve C corresponds to di / dt = 20 mA / µs.

[0053] As shown in the figure, under the same rate of change of communication current, the signal voltage amplitude is approximately linearly related to the number of turns in the signal coil. When the number of turns increases from 50 to 200, the signal voltage amplitude increases to four times its original value (approximately 50 millivolts with 50 turns and approximately 200 millivolts with 200 turns, corresponding to curve B). This linear relationship provides direct guidance for system design: increasing the number of turns in the signal coil within permissible limits can proportionally improve the receiving sensitivity. Factors to consider in practical design include core saturation, coil size, and manufacturing feasibility.

[0054] The advantage of this invention is that increasing the number of turns in the signal coil does not affect the inductance and impedance of the bus coil. This is because there is only magnetic coupling between the signal coil and the bus coil, without a direct electrical connection. Coil A on bus 1 and coil B on bus 2 constitute the communication and power supply path, and their impedance characteristics directly affect the power supply quality to the digital electronic detonator. Increasing the number of turns in coil A or coil B will increase the series impedance of the bus, leading to an increase in the voltage drop across the bus and affecting the detonator's operation. However, this invention only increases the number of turns in the signal coil, which is not connected in series in the power supply circuit, thus not affecting the power supply quality. This design eliminates the contradiction between improved signal reception sensitivity and guaranteed power supply reliability, achieving a balance between the two.

[0055] Figure 5 The effect of core saturation on signal voltage was also demonstrated. When the number of turns in the signal coil increases to a certain extent, the magnetic flux density in the core approaches its saturation value, and the curve begins to deviate from a linear relationship. Specifically, in the high-turns region, the rate of increase in signal voltage slows down. When the number of turns exceeds 150, the curve begins to deviate significantly from a linear relationship because the magnetic flux density in the core is close to the saturation magnetic flux density of the manganese-zinc ferrite material (approximately 450 millitalas). Core saturation leads to signal distortion and decreased sensitivity, while also increasing hysteresis loss and eddy current loss. Therefore, in system design, it is necessary to rationally select the number of turns in the signal coil based on the saturation magnetic flux density of the core material to achieve a balance between sensitivity and linearity. In this embodiment, considering factors such as sensitivity, linearity, and losses, the preferred number of turns in the signal coil is 100 to 150 turns.

[0056] Simulation results also show that different communication current change rates correspond to different signal voltage amplitudes. The larger the change rate, the larger the signal voltage. At di / dt = 20 mA / µs, a 200-turn signal coil can generate approximately 400 mV of signal voltage, while at di / dt = 5 mA / µs, only about 100 mV of signal voltage can be generated under the same conditions. This means that rapidly changing communication edges can generate larger signal voltages, which is beneficial for detection and identification by the receiving circuit. In practical applications, the current change rate can be improved by optimizing the communication protocol, for example, by using a steeper drive edge or increasing the amplitude of the drive current, but power consumption and detonator lifespan must be considered.

[0057] In another embodiment, reference Figure 6 As shown, the complete electronic detonator communication system architecture and signal flow are described in detail.

[0058] The electronic detonator communication system of this invention consists of a detonator, a bus, a digital electronic detonator, and a communication signal receiving circuit designed in this invention. During operation, the system comprises two independent signal loops: a power supply loop and a communication signal loop. These two loops are connected by magnetic coupling, achieving electrical isolation. The power supply loop consists of an H-bridge circuit, the DC component of the bus, and the internal circuitry of the digital electronic detonator. The communication signal loop consists of a communication modulation circuit, the AC component of the bus, and a signal receiving circuit. The two loops share the same physical bus (bus 1 and bus 2), but are electrically independent, transmitting different signal components respectively.

[0059] The power supply circuit is provided with a constant DC voltage by the H-bridge circuit of the detonator. This voltage is applied to the digital electronic detonator via a bus to power the internal chip of the detonator. When the DC component of the bus flows through the digital electronic detonator, it generates a constant magnetic flux in the dual-core coupling module. Since this magnetic flux does not change with time, according to Faraday's law of electromagnetic induction, it will not induce a voltage in the signal coil. Therefore, there is no DC electrical coupling between the power supply circuit and the signal receiving circuit; they are independent and do not interfere with each other. When the bus is supplying power to the digital electronic detonator, the current in the circuit is essentially constant. The resistance of the signal receiving circuit to the constant current is only generated by the resistance of the signal coil itself. Since the resistance of the signal coil is usually only a few ohms, its impact on the power supply is negligible.

[0060] The communication signal circuit consists of the communication modulation circuit of the digital electronic detonator, the AC component in the bus, and the signal receiving circuit of this invention. When data needs to be transmitted, the digital electronic detonator controls the internal switching device to cause the bus current to jump between I0 and I1, generating the AC signal required for communication. This current jump generates a changing magnetic flux in magnetic cores A and B, and the changing magnetic flux induces a voltage U in the signal coil. 信号=-N×(dΦtotal / dt). Specifically, when the current jumps from I0 to I1, the magnetic flux increases, and the induced voltage spikes positively; when the current falls back from I1 to I0, the magnetic flux decreases, and the induced voltage spikes negatively. The induced voltage is output through the signal coil to the differential amplifier circuit for amplification. The amplified signal is then sent to the decoding circuit for digitization processing, ultimately recovering the data sent by the digital electronic detonator.

[0061] Figure 6 The diagram also indicates the power flow directions of the power supply and signal circuits. Power flows from the detonator to the digital electronic detonator, providing energy; this flow is unidirectional and amounts to several watts. Signal power flows from the digital electronic detonator to the detonator, carrying communication information; this flow is also unidirectional and amounts to milliwatts. The two circuits flow in opposite directions but are connected via magnetic coupling, without any DC electrical connection. This design ensures both reliable communication and electrical isolation, resulting in high safety. Electrical isolation means there is no direct current path between devices at different ground potentials, avoiding interference and safety hazards caused by ground loops.

[0062] In terms of system integration, the signal receiving circuit of this invention can be integrated into the detonator as an independent module. The input terminal of the signal receiving circuit module is connected to the bus (between bus 1 and bus 2), and the output terminal is connected to the decoding circuit. The module internally includes a dual-core coupling structure, a differential amplifier circuit, and necessary filtering and protection circuits. The dual-core coupling structure is mounted on the PCB board using a surface-mount package, approximately 5 mm in height, making it compact and easy to integrate. The differential amplifier circuit uses an integrated circuit solution, with the TL072 chip containing two independent operational amplifiers, supporting dual-supply or single-supply operation. The filtering circuit uses a second-order low-pass filter with a cutoff frequency designed at 100 kHz, effectively filtering out high-frequency noise. The protection circuit includes input overvoltage protection, output short-circuit protection, and reverse power connection protection, improving the module's reliability. This modular design facilitates the design and maintenance of the detonator and also provides convenience for upgrading existing digital electronic detonator systems. In field use, simply connect the existing detonator's bus to the input terminal of the signal receiving circuit module and the module's output terminal to the decoding circuit; no large-scale modification of the original system is required.

[0063] In another embodiment, Figure 7 and Figure 8 As shown, the structure of the electronic detonator communication signal receiving circuit of the present invention will be described in detail.

[0064] In existing technology, the detonator supplies power and communicates with the digital electronic detonator via an H-bridge circuit. The H-bridge has two leads, bus 1 and bus 2, connected to the digital electronic detonator. A sampling resistor R is connected in series on the bus, and an amplifier circuit is connected across R. When the electronic detonator sends data to the detonator, the magnitude of the communication current flowing through the detonator is controlled, resulting in different voltages across the sampling resistor R. The amplifier circuit collects and amplifies this voltage, and the detonator decodes the information contained within it. In this scheme, bus 1 and bus 2 serve as both signal and power supply paths, sharing the same physical channel. Because the sampling resistor R needs to simultaneously meet the requirements of signal sampling and power supply, its value is strictly limited, typically between 10 and 20 ohms. This range limits the detonator's ability to amplify the communication current signal, and the single-ended sampling amplifier circuit lacks common-mode interference suppression capability.

[0065] Furthermore, such as Figure 7 and Figure 8 As shown, this invention uses two identical toroidal magnetic cores stacked together, with core A on top and core B below. Bus 1 is wound around the upper end of core A, forming coil A. Bus 2 is wound around the lower end of core B, forming coil B. Coils A and B have the same number of turns but opposite directions. The lower part of core A and the upper part of core B are attached together, sharing a signal coil, the two ends of which are connected to the input port of the amplifier circuit. The current signal in bus 1 is coupled to the signal coil through core A; the current signal in bus 2 is coupled to the signal coil through core B. Because there is an air gap at the joint of cores A and B, the magnetic circuits of the two cores are independent, so the current signal in bus 1 will not directly interfere with bus 2, and vice versa.

[0066] When the digital electronic detonator sends information to the detonator, a communication current flows in the bus. For magnetic core A, this current flows in from the left side and out from the right side of coil A, generating a counterclockwise magnetic flux ΦA. For magnetic core B, this current flows in from the right side and out from the left side of coil B, generating a clockwise magnetic flux ΦB. Because coils A and B have the same number of turns and the same signal current, ΦA and ΦB are the same value.

[0067] ΦA and ΦB pass through the signal coil in the same direction, and the total magnetic flux Φtotal in the signal coil is equal to ΦA + ΦB. This total magnetic flux generates a signal voltage Usignal = -N × (dΦtotal / dt) in the signal coil, where N is the number of turns in the signal coil. This voltage is collected and amplified by the amplifier circuit to obtain the current signal in the bus. The core of this differential coupling design is that two coil currents in opposite directions generate two magnetic flux signals in the same direction, making the total magnetic flux in the signal coil twice that of a single magnetic core, significantly improving signal reception sensitivity.

[0068] Although the present invention has been specifically described above with reference to preferred embodiments, it should be understood that the present invention is not limited to the embodiments described above. Various modifications and variations can be made by those skilled in the art without departing from the spirit of the present invention, and such modifications and variations should fall within the scope defined by the appended claims and their equivalents.

Claims

1. A method for receiving communication signals from an electronic detonator, characterized in that, Includes the following steps: Allow communication current to flow through the bus; The communication current generates a first magnetic flux ΦA in the first coil and a second magnetic flux ΦB in the second coil, wherein the first coil and the second coil have the same number of turns and are wound in opposite directions, for generating the first magnetic flux ΦA and the second magnetic flux ΦB of equal magnitude under the same communication current; The first magnetic flux ΦA and the second magnetic flux ΦB are made to pass through the signal coil in the same direction, thus combining to form a total magnetic flux: F 总 =ΦA+ΦB; Make the total magnetic flux Φ 总 Excite signal voltage U in the signal coil 信号 =-N×(dΦ 总 / dt), where N is the number of turns of the signal coil; The signal voltage is acquired and amplified to obtain the useful signal corresponding to the communication current.

2. The electronic detonator communication signal receiving method according to claim 1, characterized in that, When common-mode interference current appears on the bus: For the first coil, the direction of the first common-mode magnetic flux ΦA' generated by the common-mode interference current is opposite to the direction of the first magnetic flux ΦA; For the second coil, the direction of the second common-mode magnetic flux ΦB' generated by the common-mode interference current is the same as the direction of the second magnetic flux ΦB; The first common-mode magnetic flux ΦA' and the second common-mode magnetic flux ΦB' are reversed and passed through the signal coil to synthesize a total magnetic flux Φ. 总' =ΦA'-ΦB'=0; A constant magnetic flux does not generate voltage, thereby suppressing the common-mode interference.

3. The electronic detonator communication signal receiving method according to claim 1, characterized in that, The first coil and the second coil have the same number of turns, but are wound in opposite directions, thereby generating the first magnetic flux ΦA and the second magnetic flux ΦB of equal magnitude under the same communication current.

4. The electronic detonator communication signal receiving method according to claim 1, characterized in that, Both the first magnetic core and the second magnetic core are toroidal magnetic cores. There is an air gap at the joint of the two toroidal magnetic cores, and the magnetic circuits of the two magnetic cores are independent of each other.

5. The electronic detonator communication signal receiving method according to claim 1, characterized in that, When the bus is supplying power to the digital electronic detonator, the current in the circuit is constant, and the only obstacle to the current in the signal receiving circuit is the resistance in the coil.

6. The electronic detonator communication signal receiving method according to claim 1, characterized in that, The amplification factor of the communication current signal is increased by increasing the number of turns N of the signal coil, while keeping the number of turns of the first coil and the second coil unchanged, in order to suppress the influence on the power supply of the digital electronic detonator.

7. The electronic detonator communication signal receiving method according to claim 1, characterized in that, The steps of acquiring and amplifying the signal voltage specifically include: connecting the two ends of the signal coil to the input port of the differential amplifier circuit; performing differential amplification on the signal voltage through the differential amplifier circuit; and outputting the amplified voltage signal to the decoding circuit for information decoding.

8. The method for receiving communication signals from an electronic detonator according to any one of claims 1 to 7, characterized in that, It also includes a filter circuit connected in series between the signal coil and the amplifier circuit to filter out high-frequency noise.

9. An electronic detonator communication signal receiving system, used to implement the electronic detonator communication signal receiving method as described in any one of claims 1 to 7, characterized in that, include: A dual-core coupling module includes a first core and a second core. A first coil is wound on the first core, and a second coil is wound on the second core. The first coil and the second coil have the same number of turns but are wound in opposite directions. A signal coil is disposed at the contact point between the first magnetic core and the second magnetic core, and is used to receive the magnetic flux signal after differential coupling and to excite the signal voltage; An amplifier circuit module, connected to the signal coil, is used to acquire and amplify the signal voltage U excited by the signal coil. 信号 =-N×(dΦ 总 / dt); A decoding module, connected to the amplifier circuit module, is used to decode the amplified voltage signal into data information; When the digital electronic detonator sends information to the detonator, the communication current in the bus generates a first magnetic flux ΦA and a second magnetic flux ΦB of equal magnitude in the first coil and the second coil, respectively. The magnetic flux signal is synthesized by the signal coil and then collected and amplified in the amplifier circuit module. Finally, the information is decoded by the decoding module.

10. A communication signal receiving circuit for an electronic detonator, characterized in that, include: Both the first and second magnetic cores are ring-shaped structures and are fitted together, with an air gap at the fitting point. The first coil is wound on the first magnetic core and connected to the first bus. The second coil is wound on the second magnetic core and connected to the second bus. The first coil and the second coil have the same number of turns but are wound in opposite directions. A signal coil is wound around the joint between the first magnetic core and the second magnetic core; The differential amplifier circuit has its input terminal connected to both ends of the signal coil. The communication current generates a first magnetic flux ΦA in the first coil and a second magnetic flux ΦB in the second coil. ΦA and ΦB pass through the signal coil in the same direction to combine into a total magnetic flux. Φ 总 =ΦA+ΦB, Excitation signal voltage U 信号 =-N×(dΦ 总 / dt); When common-mode interference occurs, the total magnetic flux Φ is synthesized. 总' =ΦA'-ΦB'=0, used for common-mode interference suppression.

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