Wide-band spatial electric field detection head based on current detection and piezoelectric medium, its detection circuit and detection method

Abstract

The present invention provides a broadband spatial electric field detection head based on current detection and piezoelectric media, its detection circuit and its detection method, which relates to the technical field of electric field detection. The detection head includes a piezoelectric medium, an upper electrode plate and a lower electrode plate disposed on the upper and lower surfaces of the piezoelectric medium, and a semi-circular electrode disposed above the upper electrode plate; the semi-circular electrode is connected to the upper electrode plate through a conductive medium, and the semi-circular electrode is supported and connected to the lower electrode plate through an insulating medium; each of the upper and lower electrode plates is provided with a variable capacitance substrate, and the two variable capacitance substrates are bent on one side of the piezoelectric medium and a conductive layer is attached to the surface; the two conductive layers are arranged in parallel with a predetermined gap on one side, and the overlapping area of their projection surfaces can be changed within a predetermined range to form a variable capacitance, and the variable capacitance is connected to an external detection circuit. The present invention uses the deformation of the piezoelectric medium to generate a variable capacitance and uses a double-current differential circuit for detection, so as to reflect the magnitude of the spatial electric field, with low power consumption and good applicability.

Description

Technical Field

[0001] The present invention relates to the technical field of electric field detection, and in particular, to a broadband spatial electric field detector based on current detection and piezoelectric medium, its detection circuit, and its detection method. Background Art

[0002] AC and DC voltages in the power grid will generate an electric field of 0 - 50 Hz. In addition, under the condition of high proportion of new energy and high proportion of power electronic devices in the double-high environment, there are high-order harmonics in the voltage, thus generating an electric field of dozens of kHz. Solving the problem of measuring broadband electric fields in the power system has great practical engineering value.

[0003] The currently used technologies are roughly divided into three types:

[0004] (1) Electrostatic induction technology, for example, using a d-dot probe to detect the spatial electric field to achieve voltage inversion and status monitoring.

[0005] Electrostatic induction technology cannot detect DC electric fields because, under DC conditions, the equivalent capacitance of the probe makes the capacitive reactance reach nearly infinity, and the induced charges cannot be released to form an induced current, so the magnitude of the electric field cannot be measured.

[0006] (2) MEMS technology, which is an improvement of electrostatic induction technology. By applying an excitation source, the shielding electrode and the induction electrode in the chip move periodically, so that the induced charges under the DC electric field can generate an alternating periodic frequency, and the induced current is output, thereby measuring the DC electric field.

[0007] MEMS technology is costly and has a complex manufacturing process. It requires a nanoscale process to build a microelectromechanical chip, prepare a vibrating membrane, a shielding electrode, a driving electrode, and an induction electrode. The structure is very complex. It is suitable for factory electrostatic detection with extremely high precision requirements and extremely weak field strength, and has poor applicability to the strong electric field environment of the power system and is easily damaged.

[0008] (3) Photoelectric effect technology, which is represented by the Pockels effect, that is, the refractive index of the optical medium changes linearly in the electric field. By detecting the polarization angle with an external light source, the magnitude of the electric field is indirectly obtained to achieve electric field detection.

[0009] Similar to MEMS technology, the photoelectric effect technology is costly and requires special optical media, laser sources, and polarizers. The overall device has high power consumption and is suitable for developing large-scale power equipment such as ultra-high voltage voltage and current transformers, but it is overkill for electric field detection. Summary of the Invention

[0010] Objective of the Invention: To propose a broadband spatial electric field detector based on current detection and piezoelectric media, and further propose a detection circuit cooperating with the detector, and also propose a broadband spatial electric field detection method implemented based on the detector, so as to achieve low-power and high-precision detection of broadband spatial electric fields.

[0011] To solve the above technical problems, in the first aspect of the present invention, a broadband spatial electric field detector based on current detection and piezoelectric media is proposed. The detector includes:

[0012] Piezoelectric media;

[0013] An upper electrode plate and a lower electrode plate, which are respectively arranged on the upper and lower surfaces of the piezoelectric media; the lengths of the upper electrode plate and the lower electrode plate exceed the lengths of the upper and lower surfaces of the piezoelectric media;

[0014] A semi-circular electrode, which is arranged above the upper electrode plate; the semi-circular electrode is connected to the upper electrode plate through a conductive medium, and the semi-circular electrode is supported and connected to the lower electrode plate through an insulating medium;

[0015] Each of the upper electrode plate and the lower electrode plate is provided with a variable capacitor substrate. After the two variable capacitor substrates are bent on one side of the piezoelectric media respectively, a first gap is formed; a conductive layer is attached to the surface of each of the two variable capacitor substrates after being bent towards the piezoelectric media side; the overlapping area of the projection surfaces of the two conductive layers on their respective variable capacitor substrates can vary within a predetermined range, thereby forming a variable capacitor C E ;

[0016] Variable capacitor C E Connected to the detection circuit.

[0017] In a further embodiment of the first aspect, the variable capacitor substrate is in an L shape, its first contact plate is attached to the upper electrode plate or the lower electrode plate, the second contact plate is perpendicular to the upper electrode plate or the lower electrode plate, and a first gap is formed between the two second contact plates.

[0018] The conductive layer is closely attached to the opposite sides of the second contact plates of the variable capacitor substrate. The conductive layer located at the upper electrode plate is a movable first conductive layer; the conductive layer located at the lower electrode plate is a fixed second conductive layer, finally forming a pattern of "first conductive layer - contact plate - contact plate - second conductive layer". A wire is led out from each of the first conductive layer and the second conductive layer and connected to an external detection circuit, thus regarded as a variable capacitor.

[0019] The externally applied spatial electric field acts on the semi-circular electrode. Under the inverse piezoelectric effect, the piezoelectric medium deforms, thereby driving the parallel movement of the two conductive layers, changing the overlapping area of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitance substrate. The deformation of the piezoelectric medium has a functional relationship with the magnitude of the externally applied spatial electric field.

[0020] In addition, in a further embodiment of the first aspect, the calibration capacitor originally provided in the detection circuit can be directly embedded in the broadband spatial electric field detection head to obtain a variant solution of this detection head. In this solution, the detection head is additionally provided with a first calibration capacitor substrate and a second calibration capacitor substrate.

[0021] The first calibration capacitor substrate is led out through the insulating medium located between the semi-circular electrode and the lower electrode plate. A third conductive layer is attached to the first calibration capacitor substrate.

[0022] The second calibration capacitor substrate is led out through the lower electrode plate. A fourth conductive layer is attached to the second calibration capacitor substrate. The overlapping areas of the projection surfaces of the third conductive layer and the fourth conductive layer on the first calibration capacitor substrate and the second calibration capacitor substrate are fixed and unchanged, thereby forming a calibration capacitor C0.

[0023] In this solution, a wire is led out from each of the first conductive layer and the third conductive layer and connected to an external detection circuit, and the second conductive layer and the fourth conductive layer are connected to the lower electrode plate.

[0024] Based on the structure of the broadband spatial electric field detection head disclosed in the first aspect and its further embodiments, in the second aspect of the present invention, the structure of the detection circuit is proposed. The variable capacitance C E and the calibration capacitor C0 are connected in parallel in this detection circuit. This detection circuit includes a first current detection module, a second current detection module, a differential amplification module, and an output module.

[0025] The first current detection module is connected in series with the variable capacitance C E The second current detection module is connected in series with the calibration capacitor C0. The differential amplification module is respectively connected to the first current detection module and the second current detection module. The output module is connected to the differential amplification module.

[0026] The spatial electric field E applied to the semi-circular electrode forms a uniform and vertically directed electric field E' between the upper electrode plate and the lower electrode plate, thereby applying an excitation voltage U to this detection circuit; the excitation voltage U passes through the variable capacitance C E to generate a capacitive current , which is detected by the first current detection module in the loop; the excitation voltage U passes through the calibration capacitor C0 to generate a calibration current , which is detected by the second current detection module in the loop; the calibration current The amplitude of [amplitude] is the starting current amplitude I0.

[0027] The differential amplification module reads the capacitive current and calculates the output current change ΔI based on the starting current amplitude I0.

[0028] The output module obtains the output QΔI of the spatial electric field according to the predetermined proportionality coefficient Q.

[0029] In a third aspect of the present invention, a broadband spatial electric field detection method based on microcurrent and inverse piezoelectric effect is proposed. This detection method needs to be implemented based on the detection head disclosed in the first aspect above, and / or the detection circuit disclosed in the second aspect. The broadband spatial electric field detection method includes the following steps:

[0030] Apply a spatial electric field E to the semi-circular electrode to generate electrostatic induction charges with the same potential as the upper electrode plate, thereby forming a uniform and vertical electric field E' between the upper electrode plate and the lower electrode plate; under the action of the electric field E', the piezoelectric medium deforms, driving the two variable capacitor substrates to move, so that the overlapping area S of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitor substrate changes.

[0031] Determine the change ΔI of the detection loop current through the functional relationship between the spatial electric field E and the overlapping area S, and obtain the output of the applied spatial electric field as QΔI according to the predetermined proportionality coefficient Q.

[0032] In a further embodiment of the third aspect, the time-varying function of the spatial electric field E E and the variable capacitor C

[0033]

[0034] In the formula, ε is the dielectric constant of the variable capacitor substrate, L is the thickness of the variable capacitor C E , S0 is the initial overlapping area of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitor substrate, and k is the proportionality coefficient of the applied spatial electric field E to the change of the overlapping area S;

[0035] The time-varying function of the capacitive current I

[0036]

[0037] In the formula, U is the excitation voltage applied to the variable capacitor C E , and C0 is the steady-state initial value of the calibration capacitor.

[0038] The change of the detection loop current Calculated according to the following formula:

[0039]

[0040] In the formula, is the angular frequency of the excitation voltage U, is the calibration current The amplitude of is a fixed constant.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects:

[0042] (1) A broadband electric field detection probe based on a piezoelectric medium is designed, with a simple structure and easy processing. The deformation of the piezoelectric medium caused by the electric field is effectively detected through the arrangement of multiple layers of electrodes.

[0043] (2) The variable capacitance generated by the deformation of the piezoelectric medium is cleverly utilized to detect the capacitive property of its circuit, so as to reflect the magnitude of the spatial electric field, and has the advantage of low power consumption.

[0044] (3) Based on the detection head and the double-current differential circuit structure of the present invention, an equivalent characterization relationship between the spatial electric field and the circuit current is proposed, realizing broadband spatial electric field detection. Description of the Drawings

[0045] Figure 1 is a schematic structural diagram of the broadband spatial electric field detection head in Embodiment 1.

[0046] Figure 2 is a schematic structural diagram of the broadband spatial electric field detection head in Embodiment 2.

[0047] Figure 3 is the working principle diagram of the variable capacitance C E in all embodiments.

[0048] Figure 4 is a schematic structural diagram of the detection circuit in Embodiment 3.

[0049] The reference numerals of each figure are as follows: semi-circular electrode 1, conductive thin wire 2, upper electrode plate 3, variable capacitance substrate 4, piezoelectric medium 5, insulating medium 6, lower electrode plate 7, first conductive layer 81, second conductive layer 82, third conductive layer 83, fourth conductive layer 84, lead wire 9. Detailed Embodiments

[0050] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, some technical features well known to the art are not described to avoid confusion with the present invention.

[0051] Embodiment 1:

[0052] This embodiment discloses a broadband space electric field detector head based on current detection and piezoelectric medium 5, as Figure 1 shown. In this solution, the detector head uses piezoelectric medium 5 as the substrate, and piezoelectric medium 5 can be piezoelectric ceramics. The inverse piezoelectric effect is utilized for electric field detection.

[0053] The piezoelectric medium 5 is made into a cuboid, and the upper and lower surfaces thereof are respectively provided with an upper electrode plate 3 and a lower electrode plate 7. The lengths of the electrode plates both exceed the lengths of the upper and lower surfaces of the piezoelectric medium 5.

[0054] Above the upper electrode plate 3 is connected a semi-circular electrode 1, and the two are connected by a conductive thin wire 2. The semi-circular electrode 1 senses the external space electric field E, generates electrostatic induction charges, and is equipotential with the upper electrode plate 3, so that the space electric field induction charges form a uniform and vertical electric field E' between the upper electrode plate 3 and the lower electrode plate 7, and E and E' are in a linear proportional relationship.

[0055] The semi-circular electrode 1 and the lower electrode plate 7 are supported and connected by an insulating medium 6.

[0056] The electric field between the upper electrode plate 3 and the lower electrode plate 7 causes the piezoelectric medium 5 to be subjected to an electric field force, thereby generating the inverse piezoelectric effect, that is, deforming under the action of the electric field force.

[0057] Variable capacitance substrates 4 are also provided between the upper electrode plate 3 and the lower electrode plate 7, one on each of the upper and lower sides, forming a pair. The variable capacitance substrate 4 is in an L shape, its first contact plate is attached to the upper electrode plate 3 or the lower electrode plate 7, and the second contact plate is perpendicular to the upper electrode plate 3 or the lower electrode plate 7. A gap is left between the second contact plates to reduce friction.

[0058] The second contact plate of the variable capacitance substrate 4 located at the upper electrode plate 3 is attached to the first conductive layer 81; the second contact plate of the variable capacitance substrate 4 located at the lower electrode plate 7 is attached to the second conductive layer 82. Each of the first conductive layer 81 and the second conductive layer 82 has a lead wire 9 for accessing an external detection circuit.

[0059] The externally applied space electric field acts on the semi-circular electrode 1. Under the inverse piezoelectric effect, the piezoelectric medium 5 deforms, thereby driving the first conductive layer 81 to move downward or upward, causing the overlapping area of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitance substrate 4 to change; the deformation of the piezoelectric medium 5 and the magnitude of the externally applied space electric field are in a functional relationship.

[0060] Embodiment 2:

[0061] Based on Embodiment 1, this embodiment discloses a variant scheme of the broadband spatial electric field detection head. Under this scheme, some components originally belonging to the external detection circuit are embedded in the detection head, and its cross-sectional structure is as shown in Figure 2 shown. Its components include a substrate, an upper electrode plate 3, a lower electrode plate 7, a semi-circular electrode 1, an insulating medium 6, a variable capacitance substrate 4, a calibration capacitance substrate, and several conductive layers.

[0062] The detection head under this variant scheme still uses a piezoelectric medium 5 as the substrate, and the piezoelectric medium 5 is made into a cuboid. The piezoelectric medium 5 can be a piezoelectric ceramic.

[0063] The upper electrode plate 3 and the lower electrode plate 7 are respectively arranged on the upper and lower surfaces of the piezoelectric medium 5, and the lengths of the two electrode plates both exceed the lengths of the upper and lower surfaces of the piezoelectric medium 5.

[0064] The semi-circular electrode 1 is connected to the upper electrode plate 3 through a conductive thin wire 2, and the semi-circular electrode 1 and the lower electrode plate 7 are supported and connected through the insulating medium 6.

[0065] There are two variable capacitance substrates 4, which are respectively arranged on the upper electrode plate 3 and the lower electrode plate 7. The variable capacitance substrate 4 is in an L shape, its first contact plate is attached to the upper electrode plate 3 or the lower electrode plate 7, and the second contact plate is perpendicular to the upper electrode plate 3 or the lower electrode plate 7. A millimeter-level gap is left between the second contact plates to reduce friction (depending on the process, 0.5 mm to 1 mm can be selected, and the smaller the gap, the better under the condition that there is no direct contact and friction between the two). The second contact plate of the upper variable capacitance substrate 4 is attached to the first conductive layer 81; the second contact plate of the lower variable capacitance substrate 4 is attached to the second conductive layer 82.

[0066] The calibration capacitance substrate includes a first calibration capacitance substrate and a second calibration capacitance substrate, and a gap is reserved between the first calibration capacitance substrate and the second calibration capacitance substrate (there is no relative movement between the first calibration capacitance substrate and the second calibration capacitance substrate, and no unforeseen friction will be generated, so 1 mm is preferably selected considering the size and processing technology).

[0067] The first calibration capacitance substrate is led out through the insulating medium 6 located between the semi-circular electrode 1 and the lower electrode plate 7. The third conductive layer 83 is attached to the first calibration capacitance substrate. The second calibration capacitance substrate is led out through the lower electrode plate 7. The fourth conductive layer 84 is attached to the second calibration capacitance substrate, forming a calibration capacitance C0.

[0068] Under this scheme, a wire is led out from each of the first conductive layer 81 and the third conductive layer 83 and connected to an external detection circuit, and the second conductive layer 82 and the fourth conductive layer 84 are connected to the lower electrode plate 7.

[0069] In both Embodiment 1 and Embodiment 2, the working principle is as follows Figure 3 As shown, under the action of the electric field force and the inverse piezoelectric effect, the piezoelectric medium 5 deforms, which is reflected by the change in the distance between the upper electrode plate 3 and the lower electrode plate 7. As a result, it will stretch and compress to drive the variable capacitor substrate 4 to move, changing the overlapping area of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitor substrate 4, causing the overall equivalent capacitance to change. The output end of the probe is led out by the conductive layer and the lead wire 9. The conductive layer is perpendicular to the upper and lower electrode plates 7, so that it is not affected by the electrostatic induction of the electric field and is only affected by the moving force

[0070] Embodiment 3:

[0071] This embodiment discloses a detection circuit that can be connected to the probe of Embodiment 1 and / or Embodiment 2, as shown in Figure 4 As shown. A variable capacitor C E is formed on the branch where the first conductive layer 81 is connected. The capacitance value changes due to the deformation of the piezoelectric medium 5, and the deformation of the piezoelectric medium 5 has a functional relationship with the magnitude of the external electric field

[0072] This detection circuit consists of a first current detection module, a second current detection module, a differential amplification module, and an output module. The first current detection module is connected in series with the variable capacitor C E ; the second current detection module is connected in series with the calibration capacitor C0. The differential amplification module is respectively connected to the first current detection module and the second current detection module. The output module is connected to the differential amplification module. The spatial electric field E applied to the semi-circular electrode 1 forms a uniform and vertical electric field E' between the upper electrode plate 3 and the lower electrode plate 7, thereby applying an excitation voltage U to this detection circuit. The excitation voltage U generates a capacitive current E through the variable capacitor C , which is detected by the first current detection module in the loop. The excitation voltage U generates a calibration current through the calibration capacitor C0, which is detected by the second current detection module in the loop; the amplitude of the calibration current is the starting current amplitude I0. The differential amplification module reads the capacitive current , and calculates the output current change ΔI based on the starting current amplitude I0. The output module obtains the output quantity QΔI of the spatial electric field according to the pre-determined proportional coefficient Q

[0073] Embodiment 4:

[0074] Based on the foregoing Embodiment 3, this embodiment discloses a broadband spatial electric field detection method

[0075] Apply a spatial electric field E to the semi-circular electrode 1 to generate electrostatic induction charges that are equipotential with the upper electrode plate 3, thereby forming a uniform and vertically directed electric field E' between the upper electrode plate 3 and the lower electrode plate 7; under the action of the electric field E', the piezoelectric medium 5 deforms, driving the two variable capacitor substrates 4 to move, causing the overlapping area S of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitor substrate 4 to change;

[0076] Determine the change amount ΔI of the detection circuit current through the functional relationship between the spatial electric field E and the overlapping area S, and obtain the output amount of the applied spatial electric field as QΔI according to the pre-determined proportional coefficient Q.

[0077] Apply an excitation voltage U to the variable capacitor C E Then a capacitive current I will be generated. Under the action of an external electric field, the variable capacitor changes as a function, so that the current I changes as a function. Therefore, the magnitude of the spatial electric field can be deduced by detecting the capacitive current I.

[0078] The excitation voltage U can be a low-frequency sine wave voltage source with a frequency lower than 5 Hz. Under the alternating voltage, C E Has alternating induced charges, causing a current to flow through the circuit and thus can be detected. Keep the total impedance R of the current detection circuit much smaller than the equivalent impedance of C E The circuit is mainly capacitive current and does not generate active power. Therefore, the present invention has the characteristic of low power consumption.

[0079] If the magnitude of the externally applied electric field is linearly related to the area of the variable capacitor plate, then the detection circuit current I satisfies:

[0080]

[0081] ε is the dielectric constant of the material of the variable capacitor substrate 4, L is the thickness of the variable capacitor, S0 is the initial overlapping area of the projection surfaces of the two conductive layers on the second contact plate of the variable capacitor substrate 4, and k is the proportional coefficient of the externally applied electric field to the change in the overlapping area.

[0082] Furthermore, it can be obtained that:

[0083]

[0084] K is a coefficient, K = kε / L; C0 is the steady-state initial value of the variable capacitor.

[0085] Let U = U0sin(wt), w = 2πf, representing the angular frequency of the excitation source U. Then there is:

[0086]

[0087]

[0088] K1 represents the transformed proportionality coefficient, and I0 is the initial current amplitude of the circuit, which is a fixed constant.

[0089] As Figure 4 shown, a reference loop is set up. The loop capacitance is C0 and is composed of the Figure 1 and Figure 2 capacitive substrates, and the overlapping area is fixed at S0. Through double-loop current detection and differential amplification, an output QΔI linearly related to ΔI(t) = I(t) - I0cos(wt) is obtained.

[0090] (1) When the externally applied spatial electric field is a DC electric field, ; at this time, there is:

[0091]

[0092] According to the above formula, can be obtained. At this time, only the proportionality coefficient Q needs to be determined, and then the magnitude of the externally applied electric field can be calculated based on the measured differential amplification value ΔI of the double-loop current.

[0093] The proportionality coefficient Q can be obtained by linearly fitting the electric field magnitude and the output differential amplification current ΔI through laboratory simulation of the spatial electric field, which will not be elaborated here.

[0094] (2) When the externally applied spatial electric field is a power frequency electric field with high harmonic components:

[0095] ; since is greater than or equal to 50, that is, much greater than , so there is:

[0096]

[0097]

[0098] The above derivation shows that for a power frequency electric field with high harmonics, there is also . Multiplying the detected differential amplification current by the proportionality coefficient can easily obtain the magnitude of the externally applied electric field and its variation relationship with the time function. Similarly, the proportionality coefficient Q is the same as the value measured in the simulation experiment in the DC case.

[0099] The technical process of the broadband spatial electric field detection method disclosed in the above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination. When implemented using software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs.

[0100] If the above method is implemented in the form of software functional modules and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiments of the present application, in essence or the part that contributes to the related art, can be embodied in the form of a software product. The software product is stored in a storage medium and includes several instructions for causing an electronic device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the methods described in the embodiments of the present application. The foregoing storage medium includes: various media that can store program codes such as USB flash drives, mobile hard disks, read-only memories (ROMs), magnetic disks, or optical discs. In this way, the embodiments of the present application are not limited to any specific hardware, software, or firmware, or any combination among hardware, software, and firmware.

[0101] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes may be made to it in form and detail without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A broadband spatial electric field detection head based on current detection and piezoelectric medium, characterized in that: include: Piezoelectric dielectrics; An upper electrode plate and a lower electrode plate are respectively arranged on the upper and lower surfaces of the piezoelectric medium; the lengths of the upper and lower electrode plates exceed the lengths of the upper and lower surfaces of the piezoelectric medium; A semicircular electrode is arranged above the upper electrode plate; the semicircular electrode is connected to the upper electrode plate via a conductive medium, and the semicircular electrode is connected to the lower electrode plate via an insulating medium support; The upper electrode plate and the lower electrode plate are each provided with a variable capacitance substrate, the two variable capacitance substrates are respectively bent on one side of the piezoelectric medium to form a first gap, and a conductive layer is respectively attached to the surface of the two variable capacitance substrates after being bent toward the piezoelectric medium side; The overlapping area of ​​the projections of the two conductive layers on their respective variable capacitance substrates can be varied within a predetermined range to form a variable capacitance C E ; Variable Capacitor C E Connect external detection circuit.

2. The broadband spatial electric field detection head based on current detection and piezoelectric medium according to claim 1 is characterized in that: The variable capacitance substrate is L-shaped, with its first contact plate being in contact with the upper electrode plate or the lower electrode plate, and the second contact plate being perpendicular to the upper electrode plate or the lower electrode plate; the two second contact plates are parallel to each other, forming the first gap therebetween.

3. The broadband spatial electric field detector based on current detection and piezoelectric medium according to claim 2, characterized in that: The two conductive layers are respectively attached to the opposite sides of the second contact plate of the variable capacitance substrate; The externally applied spatial electric field acts on the semicircular electrode, and under the inverse piezoelectric effect, the piezoelectric medium is deformed, thereby driving the two conductive layers to move in parallel, so that the overlapping area of ​​the projection surface of the two conductive layers on the second contact plate of the respective variable capacitance substrate changes; The deformation of the piezoelectric medium is a function of the magnitude of the externally applied spatial electric field; The conductive layer located at the upper electrode plate is a movable first conductive layer; the conductive layer located at the lower electrode plate is a fixed second conductive layer.

4. The broadband spatial electric field detector based on current detection and piezoelectric medium according to claim 3 is characterized in that: A conducting wire is respectively led out from the first conductive layer and the second conductive layer to be connected to an external detection circuit.

5. The broadband spatial electric field detection head based on current detection and piezoelectric medium according to claim 3 is characterized in that: Also includes: A first calibration capacitor substrate is led out through an insulating medium located between the semicircular electrode and the lower electrode plate; A third conductive layer is attached to the first calibration capacitor substrate; A second calibration capacitor substrate is led out through the lower electrode plate; a fourth conductive layer is attached to the second calibration capacitor substrate, and the fourth conductive layer is electrically connected to the lower electrode plate; The first calibration capacitor substrate and the second calibration capacitor substrate are parallel to each other and form a second gap; The overlapping areas of the projection surfaces of the third conductive layer and the fourth conductive layer on the first calibration capacitor substrate and the second calibration capacitor substrate are respectively fixed to form a calibration capacitor C0; The calibration capacitor C0 is connected to the detection circuit.

6. The broadband spatial electric field detection head based on current detection and piezoelectric medium according to claim 5, characterized in that: A wire is led out from the third conductive layer to connect to an external detection circuit; A wire is led out from the first conductive layer to access an external detection circuit; and the second conductive layer is electrically connected to the lower electrode plate.

7. A detection circuit applied to the broadband spatial electric field detection head according to any one of claims 1 to 6, characterized in that: include: A first current detection module, a second current detection module, a differential amplification module, and an output module; Variable Capacitor C E and calibration capacitor C0 are connected in parallel in the detection circuit; The first current detection module and the variable capacitor C E The second current detection module is connected in series with the calibration capacitor C0; The differential amplification module is connected to the first current detection module and the second current detection module respectively; The output module is connected to the differential amplification module; The spatial electric field E applied to the semicircular electrode forms a uniform, vertical electric field E' between the upper electrode plate and the lower electrode plate, thereby applying an excitation voltage U to the detection circuit; The excitation voltage U passes through the variable capacitor C E Capacitive current , detected by the first current detection module in the loop; The excitation voltage U generates a calibration current through the calibration capacitor C0 , detected by the second current detection module in the loop; calibration current The amplitude is the starting current amplitude I0; The differential amplifier module reads the capacitive current , and based on the starting current amplitude I0, calculate the output current change ΔI; The output module obtains the output quantity QΔI of the spatial electric field according to the predetermined proportionality coefficient Q.

8. A method for detecting a broadband spatial electric field based on microcurrent and inverse piezoelectric effect, implemented based on the broadband spatial electric field detection head according to any one of claims 1 to 6, characterized in that: The broadband spatial electric field detection method comprises the following steps: Applying a spatial electric field E to the semicircular electrode generates an electrostatic induced charge with the same potential as the upper electrode plate, thereby forming a uniform, vertical electric field E' between the upper electrode plate and the lower electrode plate; under the action of the electric field E', the piezoelectric medium is deformed, driving the two variable capacitor substrates to move, so that the overlapping area S of the projection surface of the two conductive layers on the second contact plate of the variable capacitor substrate changes; The change ΔI of the detection loop current is determined through the functional relationship between the spatial electric field E and the overlapping area S of the projection surface, and according to the predetermined proportionality coefficient Q, the output of the applied spatial electric field is obtained as QΔI.

9. The broadband spatial electric field detection method based on microcurrent and inverse piezoelectric effect according to claim 8, characterized in that: Time-varying function of the electric field E in space and variable capacitor C E The following linear relationship is satisfied: ； Where ε is the dielectric constant of the variable capacitor substrate, L is the variable capacitor C E The thickness of the two conductive layers is , S0 is the initial overlapping area of ​​the projection surface of the two conductive layers on the second contact plate of the variable capacitance substrate, and k is the proportional coefficient of the applied spatial electric field E to the overlapping area change; Time-varying function of capacitive current I as follows: ； Where U is the variable capacitance C E The applied excitation voltage, C0 is the steady-state initial value of the calibration capacitor.

10. The broadband spatial electric field detection method based on microcurrent and inverse piezoelectric effect according to claim 9, characterized in that: Detect the change of loop current Calculated according to the following formula: ； In the formula, is the angular frequency of the excitation voltage U, For calibration current The amplitude is a fixed constant.

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