Broadband space electric field detection head based on current detection and piezoelectric medium, detection circuit and detection method thereof

Abstract

The invention provides a broadband space electric field detection head based on current detection and a piezoelectric medium, and a detection circuit and a detection method thereof, and relates to the technical field of electric field detection. The detection head comprises a piezoelectric medium, an upper electrode plate and a lower electrode plate which are arranged on the upper surface and the lower surface of the piezoelectric medium, and a semicircular electrode arranged above the upper electrode plate; the semicircular electrode is connected with the upper electrode plate through a conducting medium, and the semicircular electrode is connected with the lower electrode plate through an insulating medium support; the upper electrode plate and the lower electrode plate are respectively provided with a variable capacitance substrate, and the two variable capacitance substrates are provided with conductive layers on the surfaces after being bent at one side of the piezoelectric medium; the two conductive layers are arranged in parallel at a predetermined gap on one side, the overlapping area of the projection surfaces of the two conductive layers can be changed within a predetermined range to form a variable capacitor, and the variable capacitor is connected with an external detection circuit. Variable capacitance is generated through piezoelectric medium deformation, detection is carried out through a double-current differential loop, and therefore the size of a space electric field is reflected, power consumption is low, and applicability is good.

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 detection head based on current detection and piezoelectric medium, a detection circuit and a detection method thereof. Background Art

[0002] The AC and DC voltages in the power grid will generate 0-50 Hz electric fields. In addition, under the dual-high environment, high proportion of new energy and high proportion of power electronic devices, the voltage has high-order harmonics, which will generate electric fields of tens of kHz. Solving the measurement problem of broadband electric fields in power systems has great practical engineering value.

[0003] There are three main types of technologies currently in use:

[0004] (1) Electrostatic induction technology, such as using D-dot probes to detect the electric field in space to achieve voltage inversion and state monitoring.

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

[0006] (2) MEMS technology: This technology is an improvement on electrostatic induction technology. By applying an excitation source, the shielding electrode and the sensing electrode in the chip are caused to move periodically, so that the induced charge under the DC electric field can produce an alternating periodic frequency and output the induced current, thereby measuring the DC electric field.

[0007] MEMS technology is expensive and has a complex manufacturing process. It requires nanoscale technology to construct micro-electromechanical chips and prepare vibration membranes, shielding electrodes, drive electrodes and sensing electrodes. The structure is very complex and is suitable for factory electrostatic detection with particularly high precision requirements and weak field strength. It has poor applicability to the strong electric field environment of the power system and is easily damaged.

[0008] (3) Photoelectric effect technology. This technology is represented by the Pockels effect, that is, the refractive index of the optical medium will change linearly in the electric field. The electric field size can be indirectly obtained by detecting the polarization angle through the external light source, thereby realizing electric field detection.

[0009] Like MEMS technology, photoelectric effect technology is expensive and requires special optical media, laser sources and polarizers. The overall equipment consumes a lot of power and is suitable for the development of large-scale power equipment such as ultra-high voltage current transformers, but it is a waste of resources for electric field detection. Summary of the invention

[0010] Purpose of the invention: To propose a broadband spatial electric field detection head based on current detection and piezoelectric medium, and further propose a detection circuit that cooperates with the detection head, and also propose a broadband spatial electric field detection method based on the detection head, so as to realize low-power and high-precision detection of broadband spatial electric fields.

[0011] In order to solve the above technical problems, the first aspect of the present invention provides a broadband spatial electric field detection head based on current detection and piezoelectric medium, the detection head comprising:

[0012] Piezoelectric dielectrics;

[0013] 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;

[0014] 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;

[0015] The upper electrode plate and the lower electrode plate are each provided with a variable capacitance substrate, and the two variable capacitance substrates are respectively bent on one side of the piezoelectric medium to form a first gap; a conductive layer is respectively attached to the surface of the two variable capacitance substrates after being bent toward the piezoelectric medium; the overlapping area of ​​the projection surface of the two conductive layers on the respective variable capacitance substrates can be changed within a predetermined range, thereby forming a variable capacitance C E ;

[0016] Variable Capacitor C E Connect the detection circuit.

[0017] In a further embodiment of the first aspect, the variable capacitor substrate is L-shaped, its first contact plate is in contact with 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 side of the second contact plate of the variable capacitor substrate that is away from each other. The conductive layer located at the upper electrode plate is the movable first conductive layer; the conductive layer located at the lower electrode plate is the fixed second conductive layer, and finally forms a "first conductive layer-contact plate-contact plate-second conductive layer" pattern. The first conductive layer and the second conductive layer each lead out a wire to connect to the external detection circuit, and thus are regarded as a variable capacitor.

[0019] The externally applied spatial electric field acts on the semicircular electrode, and the piezoelectric medium is deformed under the inverse piezoelectric effect, 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 variable capacitor substrate changes. The deformation of the piezoelectric medium is a function of the size of the externally applied spatial electric field.

[0020] In addition, in a further embodiment of the first aspect, the calibration capacitor originally set in the detection circuit can also be directly embedded in the broadband spatial electric field detection head to obtain a variant of the 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 between the semicircular 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, thereby forming a calibration capacitor C0.

[0023] In this solution, a wire is led out from the first conductive layer and the third conductive layer respectively to be 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 detector disclosed in the first aspect and its further embodiments, the second aspect of the present invention proposes the structure of the detection circuit. E The calibration capacitor C0 is connected in parallel in the detection circuit. The 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 and the variable capacitor C E The second current detection module is connected in series with the calibration capacitor C0. The differential amplifier module is connected to the first current detection module and the second current detection module respectively. The output module is connected to the differential amplifier module.

[0026] 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 passes through the calibration capacitor C0 to generate a calibration current , detected by the second current detection module in the loop; calibration current The amplitude is the starting current amplitude I0.

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

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

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

[0030] A spatial electric field E is applied to the semicircular electrode to generate electrostatic induced charges 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, causing the overlapping area S of the projection surface of the two conductive layers on the second contact plate of the variable capacitor substrate to change.

[0031] 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, and according to the predetermined proportionality coefficient Q, the output of the applied spatial electric field is obtained as QΔI.

[0032] In a further embodiment of the third aspect, the time-varying function of the spatial electric field E is and variable capacitor C E The following linear relationship is satisfied:

[0033]

[0034] 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 S;

[0035] Time-varying function of capacitive current I as follows:

[0036]

[0037] Where U is the variable capacitance C E The applied excitation voltage, C0 is the steady-state initial value of the calibration capacitor.

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

[0039]

[0040] In the formula, is the angular frequency of the excitation voltage U, For calibration current The amplitude 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 piezoelectric medium was designed. It has a simple structure and is easy to process. It can effectively detect the deformation of the piezoelectric medium caused by the electric field through a multi-layer electrode arrangement.

[0043] (2) The variable capacitance generated by the deformation of the piezoelectric medium is cleverly used to detect the capacitance of the loop, thereby reflecting the size of the spatial electric field, which has the advantage of low power consumption.

[0044] (3) Based on the detection head and dual current differential loop structure of the present invention, an equivalent characterization relationship between the spatial electric field and the loop current is proposed, thus realizing broadband spatial electric field detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structure of the broadband spatial electric field detection head in Example 1.

[0046] Figure 2 This is a schematic diagram of the structure of the broadband spatial electric field detection head in Example 2.

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

[0048] Figure 4 Schematic diagram of the structure of the detection circuit in Example 3.

[0049] The figures are marked as follows: semicircular electrode 1, conductive thin wire 2, upper electrode plate 3, variable capacitor substrate 4, piezoelectric dielectric 5, insulating dielectric 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 DESCRIPTION

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

[0051] Embodiment 1:

[0052] This embodiment discloses a broadband spatial electric field detection head based on current detection and piezoelectric medium 5, such as Figure 1 In this solution, the detection head uses a piezoelectric medium 5 as a substrate, and the piezoelectric medium 5 can be a piezoelectric ceramic. The inverse piezoelectric effect is used to perform 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 length of the electrode plates exceeds the length of the upper and lower surfaces of the piezoelectric medium 5.

[0054] The upper electrode plate 3 is connected to a semicircular electrode 1, and the two are connected by a conductive thin wire 2. The semicircular electrode 1 senses the external space electric field E, generates electrostatic induced charge, and has the same potential as the upper electrode plate 3, so that the space electric field induced charge forms a uniform, vertical electric field E' between the upper electrode plate 3 and the lower electrode plate 7, and E and E' are in linear proportional relationship.

[0055] The semicircular electrode 1 is supported and connected to the lower electrode plate 7 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 acted upon by the electric field force, thereby generating an inverse piezoelectric effect, that is, deformation occurs under the action of the electric field force.

[0057] A variable capacitance substrate 4 is further provided between the upper electrode plate 3 and the lower electrode plate 7, one on each side, forming a pair. The variable capacitance substrate 4 is L-shaped, with a first contact plate in contact with the upper electrode plate 3 or the lower electrode plate 7, and a second contact plate 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 capacitor substrate 4 at the upper electrode plate 3 is provided with a first conductive layer 81; the second contact plate of the variable capacitor substrate 4 at the lower electrode plate 7 is provided with a second conductive layer 82. The first conductive layer 81 and the second conductive layer 82 each have a lead wire 9 for connecting to an external detection circuit.

[0059] The externally applied spatial electric field acts on the semicircular electrode 1, and under the inverse piezoelectric effect, the piezoelectric medium 5 is deformed, thereby driving the first conductive layer 81 to move downward or upward, so that the overlapping area of ​​the projection surface of the two conductive layers on the second contact plate of the variable capacitor substrate 4 changes; the deformation of the piezoelectric medium 5 is functionally related to the size of the externally applied spatial electric field.

[0060] Embodiment 2:

[0061] Based on the first embodiment, this embodiment discloses a variant of the broadband spatial electric field detector. In this variant, some components originally belonging to the external detection circuit are embedded in the detector. The cross-sectional structure is as follows: Figure 2 Its components include a substrate, an upper electrode plate 3, a lower electrode plate 7, a semicircular electrode 1, an insulating medium 6, a variable capacitor substrate 4, a calibration capacitor substrate, and a plurality of conductive layers.

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

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

[0064] The semicircular electrode 1 is connected to the upper electrode plate 3 through a conductive thin wire 2, and the semicircular electrode 1 is connected to the lower electrode plate 7 through the support of an insulating medium 6.

[0065] There are two variable capacitor substrates 4, which are respectively arranged on the upper electrode plate 3 and the lower electrode plate 7. The variable capacitor substrate 4 is L-shaped, and its first contact plate is in contact with 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, 0.5mm~1mm can be selected. When the two are not in direct contact to generate friction, the smaller the gap, the better). The second contact plate of the variable capacitor substrate 4 located at the upper part is provided with a first conductive layer 81; the second contact plate of the variable capacitor substrate 4 located at the lower part is provided with a second conductive layer 82.

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

[0067] The first calibration capacitor substrate is led out through the insulating medium 6 between the semicircular electrode 1 and the lower electrode plate 7. The first calibration capacitor substrate is attached with a third conductive layer 83. The second calibration capacitor substrate is led out through the lower electrode plate 7. The second calibration capacitor substrate is attached with a fourth conductive layer 84 to form a calibration capacitor C0.

[0068] In this solution, a wire is led out from the first conductive layer 81 and the third conductive layer 83 to connect 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] Whether it is embodiment 1 or embodiment 2, the working principle is the same as Figure 3 As shown, under the action of electric field force and inverse piezoelectric effect, the piezoelectric medium 5 is deformed, which is reflected in the change of the distance between the upper electrode plate 3 and the lower electrode plate 7, thereby stretching and compressing the variable capacitor substrate 4 to move, changing the overlapping area of ​​the projection surface of the two conductive layers on the second contact plate of the variable capacitor substrate 4, so that the overall equivalent capacitance changes. 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, but only by the motion force.

[0070] Embodiment 3:

[0071] This embodiment discloses a detection circuit that can be connected to the detection head of embodiment 1 and / or embodiment 2, such as Figure 4 A variable capacitor C is formed on the branch connected to the first conductive layer 81. E The capacitance value is changed by the deformation of the piezoelectric medium 5, and the deformation of the piezoelectric medium 5 is a function of the external electric field.

[0072] The detection circuit is composed of a first current detection module, a second current detection module, a differential amplifier module, and an output module. 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 amplifier module is connected to the first current detection module and the second current detection module respectively. The output module is connected to the differential amplifier module. The spatial electric field E applied to the semicircular electrode 1 forms a uniform, vertical electric field E' between the upper electrode plate 3 and the lower electrode plate 7, 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 initial current amplitude I0, calculate the output current change ΔI. The output module obtains the output QΔI of the spatial electric field according to the predetermined proportionality coefficient Q.

[0073] Embodiment 4:

[0074] Based on the above-mentioned embodiment 3, this embodiment discloses a broadband spatial electric field detection method:

[0075] A spatial electric field E is applied to the semicircular electrode 1 to generate electrostatic induced charges with the same potential as the upper electrode plate 3, thereby forming a uniform, vertical 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 is deformed, driving the two variable capacitor substrates 4 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 4 changes;

[0076] 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, and according to the predetermined proportionality coefficient Q, the output of the applied spatial electric field is obtained as QΔI.

[0077] For variable capacitance C E When an excitation voltage U is applied, a capacitive current I will be generated. Under the action of the external electric field, the variable capacitance changes as a function, thereby causing the current I to change as a function. Therefore, by detecting the capacitive current I, the size of the spatial electric field can be deduced.

[0078] The excitation voltage U can be a low-frequency sinusoidal voltage source with a frequency lower than 5 Hz. E The alternating induced charge causes current to flow through the circuit and can be measured. The total impedance R of the holding and current detection circuit is much smaller than C E The equivalent impedance of the circuit is mainly capacitive current and no active power is generated, so the present invention has the characteristic of low power consumption.

[0079] The magnitude of the applied electric field is linearly related to the area of ​​the variable capacitor plate, so the detection loop 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 surface of the two conductive layers on the second contact plate of the variable capacitor substrate 4, and k is the proportional coefficient of the external electric field to the overlapping area change.

[0082] Further we can get:

[0083]

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

[0085] Assume U=U0sin(wt), w=2πf, which represents the angular frequency of the excitation source U. Then:

[0086]

[0087]

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

[0089] like Figure 4 As shown in the figure, a reference loop is set up, the loop capacitance is C0, and the Figure 1 and Figure 2 The capacitor substrate in the circuit is composed of a capacitor substrate, and the overlapping area is fixed to S0. Through dual-loop current detection and differential amplification, the output QΔI is obtained, which is linearly related to ΔI(t) = I(t)-I0cos(wt).

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

[0091]

[0092] According to the above formula, we can get At this time, we only need to determine the proportional coefficient Q, and then calculate the magnitude of the external electric field based on the differential amplification value ΔI of the measured dual-circuit current.

[0093] The proportionality coefficient Q can be obtained by simulating the space electric field in the laboratory and performing a linear fit between the electric field size and the output differential amplified current ΔI, which will not be elaborated here.

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

[0095] ;because Greater than or equal to 50, that is, much greater than , so we have:

[0096]

[0097] The above derivation shows that for the power frequency electric field containing high-order harmonics, there is also The detected differential amplified current multiplied by the proportionality coefficient can easily obtain the magnitude of the applied electric field and its relationship with time function. Similarly, the proportionality coefficient Q is consistent with the value measured in the simulation experiment under DC conditions.

[0098] The technical process of the broadband spatial electric field detection method disclosed in the above embodiment can be implemented in whole or in part by software, hardware, firmware or any other combination. When implemented by software, the above embodiment 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.

[0099] If the above method is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application can be essentially or partly reflected in the form of a software product that contributes to the relevant technology. The software product is stored in a storage medium, including several instructions to enable an electronic device (which can be a personal computer, server, or network device, etc.) to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk or an optical disk. In this way, the embodiment of the present application is not limited to any specific hardware, software or firmware, or any combination of hardware, software, and firmware.

[0100] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and details may be made without departing from the spirit and scope of the present invention as defined in 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 broadband spatial electric field detection method 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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