Time domain aviation electromagnetic soft pod hard structure miniaturization compensation device and design method

Abstract

The invention belongs to the technical field of aviation electromagnetic exploration, and particularly relates to a time domain aviation electromagnetic soft pod hard structure miniaturization compensation device and a design method.The device comprises a compensation-receiving coil and a transmitting coil, and the compensation-receiving coil and the transmitting coil are concentric; the compensation-receiving coil comprises a compensation coil and a receiving coil which are wound on the same annular framework, one terminal of the compensation coil is connected with a first point on the transmitting coil through a series impedance device, and the other terminal of the compensation coil is directly connected with a second point on the transmitting coil through a lead; and a transmitting coil interception section is arranged between the first point and the second point. The weight of exploration equipment can be reduced, and early noise brought by a primary field in the movement process is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of airborne electromagnetic exploration, and particularly relates to a time-domain airborne electromagnetic soft-hang-pod hard-structure miniaturized compensation device and a design method. BACKGROUND

[0002] An airborne electromagnetic exploration system is composed of a transmitting coil, a compensation coil and a receiving coil. When the system is working, the transmitting coil generates an induced field, and the receiving coil receives an induced signal returned by the compensation coil. The compensation coil is used to prevent the saturation of the dB / dt field signal of a high-sensitivity receiving coil in a strong magnetic field. The compensation coil needs to pass through an electric current with the same size and opposite direction as the transmitting coil. Since the system is applied in the field of aviation, the first problem is whether the weight can be reduced, and the second problem is that the traditional compensation coil and the receiving coil are connected in a soft manner, which may cause early noise in the motion process under high sensitivity.

[0003] The compensation coil of a typical system at home and abroad is placed as follows. The compensation coil of the SkyTEM system is usually arranged at the corner area of the transmitting coil, is sensitive to vibration and attitude change, and is easy to introduce additional motion noise. The Aero TEM IV system adopts an eccentric compensation mode, and has large dynamic noise. The VTEM system adopts a concentric compensation mode, and the soft connection may easily cause large early noise. The CHTEM-III-32 system developed in China adopts a concentric compensation mode, and has problems of large volume and weight. SUMMARY

[0004] Embodiments of the application provide a time-domain airborne electromagnetic soft-hang-pod hard-structure miniaturized compensation device and a design method, which solve the problems of large volume and weight and large early noise of the existing compensation structure.

[0005] According to the time-domain airborne electromagnetic soft-hang-pod hard-structure miniaturized compensation device of the first aspect of the application, the device comprises a compensation-receiving coil and a transmitting coil, the compensation-receiving coil and the transmitting coil are concentric, the compensation-receiving coil comprises a compensation coil and a receiving coil wound on the same annular framework, one terminal of the compensation coil is connected to a first point on the transmitting coil through a series impedance device, the other terminal of the compensation coil is directly connected to a second point on the transmitting coil through a lead, and the first point and the second point are a transmitting coil segment.

[0006] Further, the framework comprises a coaxial compensation coil ring and a receiving coil ring, forms a compensation coil groove in the middle and receiving coil grooves on both sides of the compensation coil groove, two receiving coil grooves are arranged on each side, the diameter of the compensation coil groove is greater than the diameter of the receiving coil groove, the compensation coil is wound in the compensation coil groove, and the receiving coil is wound in the receiving coil groove.

[0007] Further, the impedance device comprises a magnetic ring, and coils with different turns are wound on the magnetic ring, and the turns of the coils are adjusted according to the required inductance.

[0008] Further, the transmitting coil is a regular polygon structure composed of multiple circular tubes, the transmitting coil and the compensation-receiving coil are fixed in position and connected to the helicopter through a rope.

[0009] Further, the calculation formula of the turns of the coils on the magnetic ring is: , , , represents the vacuum permeability, is the relative permeability of the material of the magnetic ring, and N represents the turns of the coils wound on the magnetic ring, represents the inductance of the inductance in series with the compensation coil, is the effective cross-sectional area of the magnetic ring, represents the height of the magnetic ring, and OD and ID represent the outer diameter and the inner diameter of the magnetic ring, respectively, represents the effective magnetic path length of the magnetic ring.

[0010] Further, the resistance of the compensation coil satisfies: , is the current of the transmitting coil, is the current of the compensation coil, is the resistance of the compensation coil, is the resistance of the intercepting section of the transmitting coil; The inductance of the compensation coil satisfies: , is the time constant of the compensation coil, is the inductance of the compensation coil, is the time constant of the transmitting coil, is the inductance of the transmitting coil, is the resistance of the transmitting coil; The length of the wire wound on the compensation coil is: , is the radius of the compensation coil, is the radius of the transmitting coil; The current of the compensation coil and the turns of the compensation coil satisfy: , represents the current of the transmitting coil, represents the current of the compensation coil, represents the turns of the compensation coil, represents the mutual inductance value between the transmitting coil and the receiving coil, represents the mutual inductance value between the compensation coil and the receiving coil.

[0011] According to the design method of the time domain airborne electromagnetic soft pod hard structure miniaturization compensation device, the design method comprises the following steps: determining the physical parameters and electrical parameters of the transmitting coil, wherein the physical parameters comprise the radius of the transmitting coil, and the electrical parameters comprise the current, time constant, resistance and inductance of the transmitting coil; calculating the voltage, resistance and inductance of the transmitting coil intercepted segment through the length of the intercepted transmitting coil intercepted segment; calculating the resistance of the compensation coil: wherein is the current of the transmitting coil, is the current of the compensation coil, is the resistance of the compensation coil, is the resistance of the transmitting coil intercepted segment; calculating the inductance of the compensation coil: , is the time constant of the compensation coil, is the inductance of the compensation coil, is the time constant of the transmitting coil, is the inductance of the transmitting coil, is the resistance of the transmitting coil; calculating the length of the wire wound on the compensation coil as: , is the radius of the compensation coil, is the radius of the transmitting coil; calculating the cross-sectional area of the wire wound on the compensation coil according to the length of the wire wound on the compensation coil: , is the cross-sectional area of the wire wound on the compensation coil, is the resistivity of copper; according to the relationship between the number of turns of the compensation coil and the weight of the compensation coil: adjusting the required number of turns, wherein represents the weight of the copper wire, represents the weight of one meter long copper wire per square millimeter, represents the current of the transmitting coil, represents the current of the compensation coil, represents the number of turns of the compensation coil, represents the mutual inductance value between the transmitting coil and the receiving coil, represents the mutual inductance value between the compensation coil and the receiving coil.

[0012] Compared with the prior art, the application has the beneficial effects that the application can reduce the weight of the exploration equipment and reduce the early noise brought by the primary field in the movement process. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A structure schematic diagram of a time domain airborne electromagnetic soft pod hard structure miniaturization compensation device provided for an embodiment of the present application is shown in the figure; Figure 2 A position relation diagram of a transmitting coil and a compensation-receiving coil provided for an embodiment of the present application is shown in the figure; Figure 3 A structure schematic diagram of a framework provided for an embodiment of the present application is shown in the figure; Figure 4 A structure schematic diagram of an impedance device provided for an embodiment of the present application is shown in the figure; Figure 5 A transmitting current waveform and a compensation current waveform diagram provided for an embodiment of the present application is shown in the figure; Figure 6 A connection structure schematic diagram of a transmitting coil and a compensation coil and an impedance device provided for an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0015] The present application refers to Figure 1 As shown in the figure, a time domain airborne electromagnetic soft pod hard structure miniaturization compensation device includes a compensation-receiving coil 1, an impedance device 2, a transmitting coil intercepting section 3, a transmitting coil 4, a transmitting cable 5, a transmitter 6 and a receiver 7. The transmitter 6 belongs to a transmitting system, and is connected with the large transmitting coil 4 through the transmitting cable 5. The receiving system is composed of the receiver 7 and the compensation-receiving coil 1 embedded in the center of the transmitting coil 4. The compensation-receiving coil 1 includes a compensation coil and a receiving coil wound on the same annular framework. One terminal of the compensation coil is connected with a first point on the transmitting coil 4 through the series impedance device 2, and the other terminal of the compensation coil is directly connected with a second point on the transmitting coil 4 through a lead. The first point and the second point are the transmitting coil intercepting section 3. The impedance device 2 can ensure that a large and adjustable inductance is generated under the condition that the resistance is very small. When the system works, the transmitting coil 4 generates an excitation magnetic field, the compensation-receiving coil 1 senses a target signal, and the signal is transmitted through the lead of the impedance device 2. The impedance device 2 provides an adjustable inductance, which is adjacent to the transmitting coil intercepting section 3 to form an electromagnetic coupling optimization structure. The whole system realizes electromagnetic detection and signal analysis of underground targets through the cooperative work of the transmitting coil 4 and the compensation-receiving coil 1.

[0016] In an embodiment, referring to Figure 3As shown, the skeleton includes coaxial compensation coil ring and receiving coil ring, forming the compensation coil groove 10 in the middle, and receiving coil groove 9 on both sides of the compensation coil groove 10, two receiving coil grooves 9 are arranged on each side, the diameter of the compensation coil groove 10 is greater than the diameter of the receiving coil groove 9, the compensation coil is wound in the compensation coil groove 10, and the receiving coil is wound in the receiving coil groove 9. The diameter of the compensation coil groove 10 is 1.026 times the diameter of the receiving coil groove 9. The compensation coil is wound in the compensation coil groove 10 and reliably fixed through the hole. The receiving coil is wound in the receiving coil groove 9 and positioned and fixed by means of the hole, and the continuous winding of the receiving coil between the four receiving coil grooves 9 can be smoothly realized.

[0017] In an embodiment, the impedance device 2 includes a magnetic ring, and coils with different turns are wound on the magnetic ring to form an adjustable inductance. The formula for calculating the number of turns of the coil on the magnetic ring is: , , , represents the vacuum permeability, is the relative permeability of the magnetic ring material, and N represents the number of turns of the coil wound on the magnetic ring, represents the inductance of the inductance in series with the compensation coil, is the effective cross-sectional area of the magnetic ring, that is, the equivalent cross-sectional area of the magnetic force line passing through the magnetic ring, represents the height of the magnetic ring, OD and ID represent the outer diameter and inner diameter of the magnetic ring respectively, represents the effective magnetic path length of the magnetic ring.

[0018] In an embodiment, referring to Figure 2 , the transmitting coil 4 is a regular polygon structure composed of multiple circular tubes, and the multiple circular tubes form an approximately circular coil structure. The transmitting coil and the compensation-receiving coil 1 are fixed in position and connected to the helicopter through the rope 8. The transmitting coil 4 and the compensation-receiving coil 1 are fixed in position. The compensation coil and the receiving coil are wound on the same skeleton, thereby reducing the weight of the exploration equipment and reducing the early noise caused by the motion of the primary field.

[0019] In an embodiment, referring to Figure 6 , a double bolt nut 11 with a gasket structure and a semicircular clamp 14 combination structure are used to form two symmetrical connection points, i.e. the first point and the second point, on the sleeve 12 of the transmitting coil. The lead 13 of the compensation coil is first welded on the sleeve of the transmitting coil, and then mechanically and electrically fixed by the semicircular clamp 13 and the double bolt nut 11 with a gasket structure. The impedance device 2 is connected in series on the lead of the compensation coil. The impedance device 2 adopts a self-winding coil magnetic ring, which can adjust the inductance while ensuring a small resistance, and ensure that the inductance of the compensation coil meets the requirements.

[0020] Referring to Figure 5 As shown in the current waveform of the transmitting coil and the current waveform required to be generated by the compensation coil, the rising, flat top and falling time of the two current waveforms must be consistent if the current of the transmitting coil is to be compensated.

[0021] In the flat top phase of the current waveform, the voltage is low, and to ensure the synchronization of the current of the transmitting coil 4 and the current of the compensation coil, a resistance shunt can be used to ensure that the currents are in phase. The current of the transmitting coil intercepting section 3 is shunted to the compensation coil, so that the compensation coil generates an opposite magnetic field to offset the magnetic field generated by the transmitting coil, so that the primary field induced by the receiving coil is as close to zero as possible.

[0022] The formula of the induced electromotive force in the circuit is shown in (1), the magnetic induction intensity B is composed of two parts, one part is the magnetic induction intensity of the transmitting coil 4, and the other part is the magnetic induction intensity of the compensation coil. The formula of the induced electromotive force generated by the transmitting coil 4 in the receiving coil is shown in (2). The formula of the induced electromotive force generated by the compensation coil in the receiving coil is shown in (3). Combined with formula (1), formula (2) and formula (3), formula (4) can be derived. Wherein, M represents the mutual inductance value between the transmitting coil and the receiving coil, M represents the mutual inductance value between the compensation coil and the receiving coil. In the case of known current of the transmitting coil, the relationship between the current of the compensation coil and the number of turns of the compensation coil can be derived: (1) ; (2) ; (3) ; (4) ; Wherein, E represents the induced electromotive force, S represents the area of the compensation coil, I represents the current of the transmitting coil, I represents the current of the compensation coil, N represents the number of turns of the compensation coil, E represents the induced electromotive force generated by the transmitting coil in the receiving coil, E represents the induced electromotive force generated by the compensation coil in the receiving coil.

[0023] The inductance of the inductance required to be connected in series with the compensation coil is known, and the number of turns of the coil required to be wound on the magnetic ring is calculated according to formula (5), wherein μ0 represents the vacuum permeability, the value is 4 *10 -7 H / m, is the relative permeability of the magnetic ring material, which is a dimensionless number. N represents the number of turns of the coil wound on the magnetic ring, represents the inductance of the inductance in series with the compensation coil. is the effective cross-sectional area of the magnetic ring, i.e. the equivalent cross-sectional area through which the magnetic force line passes, calculated by formula (6). Wherein represents the height of the magnetic ring, OD and ID represent the outer diameter and inner diameter of the magnetic ring respectively. represents the effective magnetic path length of the magnetic ring, which is the average length of the closed path of the magnetic force line inside the magnetic ring, calculated by formula (7): (5); (6); (7); The relationship between the number of turns of the compensation coil and the current of the compensation coil can be determined by formula (4). Determining the length of the two connection points determines the voltage, resistance and inductance of the transmission coil section 3. The resistance shunt formula is shown in formula (8), and the resistance of the compensation coil can be calculated under the condition that the current of the transmission coil and the current of the compensation coil and the resistance of the transmission coil section 3 are known: (8).

[0024] In order to ensure that the current of the compensation coil can compensate for the current of the transmission coil, it is also necessary to ensure that the time constant of the compensation coil and the transmission coil is consistent, as shown in formula (9). Given the resistance and inductance of the transmission coil and the resistance of the compensation coil, the inductance of the compensation coil can be calculated: (9); The voltage value generated by the inductance of the compensation coil can be calculated by formula (10). The length D of the wire wound by the compensation coil can be obtained by formula (11) under the condition that the radius of the compensation coil and the radius of the receiving coil are known.

[0025] (10), (11); According to formula (12), the cross-sectional area of the wire wound by the compensation coil can be calculated, and then the wire diameter and the total weight of the winding can be calculated: (12), is the cross-sectional area of the wire wound by the compensation coil, is the resistivity of copper, is the resistance of the compensation coil.

[0026] According to formula (13), the relationship between the number of turns of the coil wound by the compensation coil and the weight of the copper wire can be calculated, which is nonlinear. Indicates the weight of the copper wire. This indicates the weight per square millimeter of a one-meter-long copper wire.

[0027] (13) In other words, the weight reduction of the compensation coil can be achieved by adjusting the number of turns of the compensation coil.

[0028] On the other hand, embodiments of this application provide a design method for a miniaturized compensation device for a time-domain airborne electromagnetic soft pod hard structure, the method comprising: The physical and electrical parameters of the transmitting coil 4 are determined. The physical parameters include the radius of the transmitting coil 4, and the electrical parameters include the current, time constant, resistance, and inductance of the transmitting coil 4. Calculate the voltage, resistance, and inductance of the cut-off segment 3 of the transmitting coil based on the length of the cut-off segment 3. Calculate the resistance of the compensation coil: ,in The current in the transmitting coil, To compensate for the current in the coil, To compensate for the coil resistance, The resistance of the segment cut off from the transmitting coil; Calculate the inductance of the compensation coil: , To compensate for the time constant of the coil, To compensate for the inductance of the coil, The time constant of the transmitting coil, The inductance of the transmitting coil, The resistance of the transmitting coil; The length of the wire wound around the compensating coil is calculated as follows: , To compensate for the radius of the coil, The radius of the transmitting coil; Calculate the cross-sectional area of ​​the winding wire of the compensation coil based on the length of the winding wire: , It is the cross-sectional area of ​​the wire wound around the compensating coil. It is the resistivity of copper; Based on the relationship between the number of turns of the compensation coil and the weight of the compensation coil: Adjust the required number of turns, where, Indicates the weight of the copper wire. This indicates the weight per square millimeter of one meter of copper wire. This represents the current in the transmitting coil. represents a current of the compensation coil, represents a number of turns of the compensation coil, represents a mutual inductance value between the transmitting coil and the receiving coil, represents a mutual inductance value between the compensation coil and the receiving coil.

[0029] The above descriptions are only the preferred embodiment of the present application, not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A miniaturized compensation device for the rigid structure of a time-domain airborne electromagnetic soft pod, characterized in that, The device includes a compensation-receiving coil (1) and a transmitting coil (4). The compensation-receiving coil (1) and the transmitting coil (4) are co-centered. The compensation-receiving coil (1) includes a compensation coil and a receiving coil wound on the same annular frame. One terminal of the compensation coil is connected to a first point on the transmitting coil (4) through a series impedance device (2). The other terminal of the compensation coil is directly connected to a second point on the transmitting coil (4) through a lead wire. The section between the first point and the second point is a cut-off segment (3) of the transmitting coil.

2. The miniaturized compensation device for the hard structure of the time-domain airborne electromagnetic soft pod according to claim 1, characterized in that, The frame includes a coaxial compensation coil ring and a receiving coil ring, forming a compensation coil groove (10) in the middle, and receiving coil grooves (9) on both sides of the compensation coil groove (10). Two receiving coil grooves (9) are provided on each side. The diameter of the compensation coil groove (10) is larger than the diameter of the receiving coil groove (9). The compensation coil is wound in the compensation coil groove (10), and the receiving coil is wound in the receiving coil groove (9).

3. The miniaturized compensation device for the hard structure of the time-domain airborne electromagnetic soft pod according to claim 1, characterized in that, The impedance device (2) includes a magnetic ring with coils of different numbers of turns wound on it, and the number of turns of the coils is adjusted according to the required inductance.

4. The miniaturized compensation device for the hard structure of the time-domain airborne electromagnetic soft pod according to claim 1, characterized in that, The transmitting coil (4) is a regular polygonal structure composed of multiple round tubes. The transmitting coil (4) and the compensation-receiving coil (1) are fixed in position and connected to the helicopter by a rope (8).

5. The miniaturized compensation device for the hard structure of the time-domain airborne electromagnetic soft pod according to claim 2, characterized in that, The formula for calculating the number of turns of the coil on the magnetic ring is: , , , Represents the permeability of free space. Where is the relative permeability of the magnetic ring material, and N represents the number of turns of the coil wound on the magnetic ring. This represents the inductance of the inductor connected in series with the compensation coil. This is the effective cross-sectional area of ​​the magnetic ring. The height of the magnetic ring is indicated by OD, and the outer and inner diameters of the magnetic ring are indicated by ID, respectively. This indicates the effective magnetic path length of the magnetic ring.

6. The miniaturized compensation device for the hard structure of the time-domain airborne electromagnetic soft pod according to claim 1, characterized in that, The resistance of the compensation coil satisfies: ,in The current in the transmitting coil, To compensate for the current in the coil, To compensate for the coil resistance, The resistance of the segment cut off from the transmitting coil; The inductance of the compensation coil satisfies: , To compensate for the time constant of the coil, To compensate for the inductance of the coil, The time constant of the transmitting coil, The inductance of the transmitting coil, The resistance of the transmitting coil; The length of the wire wound on the compensating coil is: , To compensate for the radius of the coil, The radius of the transmitting coil; The current in the compensation coil and the number of turns in the compensation coil satisfy the following: , This represents the current in the transmitting coil. This indicates the current in the compensation coil. Indicates the number of turns of the compensation coil. This represents the mutual inductance between the transmitting and receiving coils. This indicates the mutual inductance between the compensation coil and the receiving coil.

7. A design method for a miniaturized compensation device for a time-domain airborne electromagnetic soft pod rigid structure as described in any one of claims 1-6, characterized in that, This design methodology includes: Determine the physical and electrical parameters of the transmitting coil (4), the physical parameters including the radius of the transmitting coil (4), and the electrical parameters including the current, time constant, resistance and inductance of the transmitting coil (4); The voltage, resistance, and inductance of the cut-off segment (3) of the transmitting coil are calculated based on the length of the cut-off segment (3). Calculate the resistance of the compensation coil: ,in The current in the transmitting coil, To compensate for the current in the coil, To compensate for the coil resistance, The resistance of the segment cut off from the transmitting coil; Calculate the inductance of the compensation coil: , To compensate for the time constant of the coil, To compensate for the inductance of the coil, The time constant of the transmitting coil, The inductance of the transmitting coil, The resistance of the transmitting coil; The length of the wire wound around the compensating coil is calculated as follows: , To compensate for the radius of the coil, The radius of the transmitting coil; Calculate the cross-sectional area of ​​the winding wire of the compensation coil based on the length of the winding wire: , It is the cross-sectional area of ​​the wire wound around the compensating coil. It is the resistivity of copper; Based on the relationship between the number of turns of the compensation coil and the weight of the compensation coil: Adjust the required number of turns, where, Indicates the weight of the copper wire. This indicates the weight per square millimeter of one meter of copper wire. This represents the current in the transmitting coil. This indicates the current in the compensation coil. Indicates the number of turns of the compensation coil. This represents the mutual inductance between the transmitting and receiving coils. This indicates the mutual inductance between the compensation coil and the receiving coil.

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