Current sensor and chip based on magnetoelectric effect and piezoelectric effect

Abstract

The application relates to the field of electronic sensors and provides a current sensor and a chip based on magnetoelectric effect and piezoelectric effect. The current sensor comprises a support structure, a mass block, a coil, an elastic beam and a piezoelectric conversion structure arranged on the surface of the elastic beam, the mass block is connected with the elastic beam, the mass block is suspended on the support structure, and the coil is arranged on the surface of the mass block. The piezoelectric conversion structure comprises a first metal layer, a piezoelectric material layer and a second metal layer, and the piezoelectric material layer is arranged between the first metal layer and the second metal layer. The application combines the magnetoelectric effect and the piezoelectric effect, selects a magnetoelectric effect-positive piezoelectric effect working mode or a magnetoelectric effect-reverse piezoelectric effect working mode, realizes the detection of direct current and alternating current at the same time for the same current sensor, and can be applied to various current detection scenes.

Description

Technical Field

[0001] This invention relates to the field of electronic sensors, and more specifically to a current sensor based on the magnetoelectric effect and the piezoelectric effect. Background Technology

[0002] Current sensors are mainly used in modules or systems such as frequency converters, DC / DC converters, motor controllers, uninterruptible power supplies, switching power supplies, and process control. Current sensing technology is generally based on the following principles for current measurement: shunts based on Ohm's law, current sensors based on Ampere's circuital law, and indirect measurement sensors that utilize magnetic fields and other physical principles or effects.

[0003] Shunts based on Ohm's law: The voltage output across the shunt is proportional to the measured current. They are low-cost, easy to use, and suitable for general current measurement applications, primarily in current measurement applications below 50A. Current sensors based on Ampere's circuital law: These indirectly measure the magnitude and direction of current by measuring the magnetic field. They are mainly based on the following five measurement technologies: (a) Hall current sensors; (b) fluxgate current sensors; (c) magnetoresistive (MR) current sensors, including anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR), and tunneling magnetoresistive (TMR); (d) Rogowski coils; and (e) current transformers. Indirect measurement sensors: These utilize magnetic fields combined with other physical principles / effects to achieve indirect current measurement, including the photoelectric effect, the magneto-optical effect of the Faraday effect, nuclear magnetic resonance, magnetostriction, the quantum Hall effect, and superconducting quantum interference devices (SQUIDs).

[0004] With the development of semiconductor and microelectronics technologies, current sensors based on the magnetoelectric effect using MEMS (Micro-Electro-Mechanical Systems) technology have become an important development direction. Existing current sensors based on the magnetoelectric effect mainly employ structures such as electromagnetic induction circuits, magnetoelectric transducers, amplifier circuits, and coils. The magnetoelectric transducer senses an external alternating magnetic field through a permanent magnet. Because it utilizes the magnetoelectric effect or electromagnetic induction phenomenon, and relies on a permanent magnet to sense an external alternating magnetic field while the coil is fixed, this type of current sensor can only measure alternating current (AC) and cannot measure direct current (DC). Summary of the Invention

[0005] To address the aforementioned technical deficiencies, this invention provides a current sensor based on the magnetoelectric and piezoelectric effects, which can detect both direct current and alternating current.

[0006] The present invention provides a current sensor based on the magnetoelectric effect and the piezoelectric effect, comprising: a support structure, a mass block, a coil, an elastic beam, and a piezoelectric conversion structure disposed on the surface of the elastic beam;

[0007] The mass block is connected to the elastic beam, the mass block is suspended above the support structure, and the coil is disposed on the surface of the mass block;

[0008] The piezoelectric conversion structure includes a first metal layer, a piezoelectric material layer, and a second metal layer, wherein the piezoelectric material layer is disposed between the first metal layer and the second metal layer.

[0009] When the first metal layer and the second metal layer are subjected to voltage, the piezoelectric conversion structure deforms under the inverse piezoelectric effect of the piezoelectric material layer, causing the elastic beam to deform and the mass block and coil to move. The coil generates an induced current under the action of the magnetic field generated by the DC current being measured. The DC current being measured is detected by measuring the induced current of the coil.

[0010] The coil generates a magnetic field when a direct current is applied. The magnetic field generated by the coil interacts with the alternating magnetic field generated by the alternating current being measured, causing the mass block to move. The elastic beam deforms as the mass block moves, causing the piezoelectric conversion structure to deform. Under the positive piezoelectric effect, a voltage signal is generated between the first metal layer and the second metal layer. The AC current being measured is detected by measuring the voltage signal.

[0011] In this embodiment of the invention, the surface of the support structure has a cavity, and the mass block is located above the cavity.

[0012] In this embodiment of the invention, the elastic beam includes a first elastic beam and a second elastic beam. The first end of the first elastic beam and the first end of the second elastic beam are respectively fixed to the two ends of the support structure, and the second end of the first elastic beam and the second end of the second elastic beam are respectively connected to the two ends of the mass block.

[0013] In this embodiment of the invention, the mass block has a centrally symmetrical shape and has symmetrical ends;

[0014] The first elastic beam and the second elastic beam are connected to the symmetrical ends of the mass block.

[0015] In this embodiment of the invention, the planar shape of the mass block is a rectangle, a square, a circle, or a regular polygon.

[0016] In this embodiment of the invention, the coil is a planar spiral coil, and the planar shape of each turn of the planar spiral coil is a rectangle, a square, a circle, or a regular polygon.

[0017] In this embodiment of the invention, the elastic beam is a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam.

[0018] In this embodiment of the invention, the first metal layer is located on the surface of the elastic beam, the piezoelectric material layer is located on the surface of the first metal layer, and the second metal layer is located on the surface of the piezoelectric material layer.

[0019] In this embodiment of the invention, the piezoelectric conversion structure includes a first piezoelectric conversion structure and a second piezoelectric conversion structure. The first piezoelectric conversion structure is disposed on the surface of a first elastic beam, and the second piezoelectric conversion structure is disposed on the surface of a second elastic beam. The ends of the metal layers of the first and second piezoelectric conversion structures near the mass block are both grounded.

[0020] In this embodiment of the invention, the piezoelectric material of the piezoelectric material layer is at least one of AlN, ScAlN, PZT, ZnO, and PVDF.

[0021] In this embodiment of the invention, the materials of the first metal layer and the second metal layer are at least one of Pt, Mo, Al, Au, Cu, Ti, Cr, and Ag.

[0022] In this embodiment of the invention, in a DC application environment, the current sensor operates in a DC detection mode. In the DC detection mode, voltage or current is applied to the first and second metal layers of the piezoelectric conversion structure, and DC detection is achieved by measuring the induced current of the coil.

[0023] In an AC power application environment, the current sensor operates in AC detection mode. In AC detection mode, the coil is energized with DC power, and AC detection is achieved by measuring the voltage between the first and second metal layers of the piezoelectric conversion structure.

[0024] The present invention also provides a chip comprising the aforementioned current sensor based on the magnetoelectric effect and piezoelectric effect.

[0025] This invention combines the magnetoelectric and piezoelectric effects to provide a current sensor chip structure based on these effects. By selecting either a magnetoelectric-direct piezoelectric effect or a magnetoelectric-inverse piezoelectric effect operating mode, a single current sensor can simultaneously detect both DC and AC currents, making it applicable to various current detection scenarios. The chip structure design employs a single coil, a single mass block, a set of elastic beams, and a set of piezoelectric conversion structures. Compared to traditional complex assembly structures based on magnetoelectric effects, this design is easier to manufacture using MEMS micromachining technology, enabling integrated and mass production, reducing production costs, and offering significant advantages for large-scale applications in various current detection scenarios.

[0026] Other features and advantages of the technical solution of the present invention will be described in detail in the following detailed embodiments section. Attached Figure Description

[0027] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 This is a three-dimensional structural schematic diagram of the tunnel magnetoresistive accelerometer provided in an embodiment of the present invention;

[0029] Figure 2 This is a front view of the tunnel magnetoresistive accelerometer provided in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures

[0031] 1-Coil, 4a / 4b-Elastic beam, 5a / 5b-Piezoelectric conversion structure, 6a / 6b-Second metal layer,

[0032] 7a / 7b - Piezoelectric material layer, 8a / 8b - First metal layer, 10 - Mass block, 12 - Support structure. Detailed Implementation

[0033] To make the technical solutions and advantages of the embodiments of the present invention clearer, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0034] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0035] In this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] This invention provides a current sensor based on the magnetoelectric and piezoelectric effects, comprising: a support structure, a mass block, a coil, an elastic beam, and a piezoelectric conversion structure disposed on the surface of the elastic beam. The mass block is connected to the elastic beam and suspended on the support structure, while the coil is disposed on the surface of the mass block. The piezoelectric conversion structure includes a first metal layer, a piezoelectric material layer, and a second metal layer, with the piezoelectric material layer disposed between the first and second metal layers. The current sensor of this invention employs a bidirectional operating mode of magnetoelectric and piezoelectric effects. In the magnetoelectric-direct piezoelectric effect operating mode, it can detect the magnitude of direct current (DC), and in the magnetoelectric-inverse piezoelectric effect operating mode, it can detect the magnitude of alternating current (AC).

[0037] In the working mode of magnetoelectric effect-positive piezoelectric effect, when the first and second metal layers are subjected to voltage, the piezoelectric conversion structure deforms under the inverse piezoelectric effect of the piezoelectric material layer, causing the elastic beam to deform and the mass block and coil to move. The coil generates an induced current under the action of the magnetic field generated by the DC current being measured. The DC current being measured is detected by measuring the induced current of the coil.

[0038] In the magnetoelectric effect-inverse piezoelectric effect working mode, the coil generates a magnetic field when a direct current is applied. The magnetic field generated by the coil interacts with the alternating magnetic field generated by the AC current being measured, causing the mass block to move. The elastic beam deforms with the movement of the mass block, causing the piezoelectric conversion structure to deform. Under the direct piezoelectric effect, a voltage signal is generated between the first metal layer and the second metal layer. The AC current being measured is detected by measuring the voltage signal.

[0039] like Figure 1As shown, the current sensor based on magnetoelectric and piezoelectric effects provided in this embodiment of the invention includes: a support structure 12, a mass block 10, a coil 1, two elastic beams (a first elastic beam 4a and a second elastic beam 4b), and two piezoelectric conversion structures (a first piezoelectric conversion structure 5a and a second piezoelectric conversion structure 5b). The first end of the first elastic beam 4a and the first end of the second elastic beam 4b are respectively fixed to the two ends of the support structure 12. The second ends of the first elastic beam 4a and the second elastic beam 4b are respectively connected to the two ends of the mass block 10. The mass block 10 is suspended above the support structure 12, and the coil 1 is disposed on the surface of the mass block 10. The two piezoelectric conversion structures 5a / 5b are respectively disposed on the surfaces of the two elastic beams 4a / 4b, that is, the first piezoelectric conversion structure 5a is disposed on the surface of the first elastic beam 4a, and the second piezoelectric conversion structure 5b is disposed on the surface of the second elastic beam 4b. Each piezoelectric conversion structure 5a / 5b includes a first metal layer 8a / 8b, a piezoelectric material layer 7a / 7b, and a second metal layer 6a / 6b, with the piezoelectric material layer 7a / 7b disposed between the first metal layer 8a / 8b and the second metal layer 6a / 6b. Specifically, the first metal layer 8a / 8b is located on the surface of the elastic beam 4a / 4b, the piezoelectric material layer 7a / 7b is located on the surface of the first metal layer 8a / 8b, and the second metal layer 6a / 6b is located on the surface of the piezoelectric material layer 7a / 7b. The elastic beam can undergo elastic deformation under the deformation of the piezoelectric conversion structure. The mass block will be displaced under the deformation of the elastic beam, thereby driving the coil to move. The coil will be displaced under the action of an alternating magnetic field, driving the mass block to move, thus causing the elastic beam to deform. The deformation of the elastic beam causes the piezoelectric conversion structure to deform.

[0040] In this embodiment, the surface of the support structure 12 has a cavity, and the mass block 10 is suspended above the cavity. The mass block 10 has a centrally symmetrical shape with symmetrical ends. The first elastic beam 4a and the second elastic beam 4b are connected to the symmetrical ends of the mass block 10.

[0041] In this embodiment, the metal layers of the first piezoelectric conversion structure 5a and the second piezoelectric conversion structure 5b are grounded at their closest points. One end of the first and second metal layers of the first piezoelectric conversion structure is close to the mass block, and the other end is close to the fixing point between the first elastic beam and the support structure. Similarly, one end of the first and second metal layers of the second piezoelectric conversion structure is close to the mass block, and the other end is close to the fixing point between the second elastic beam and the support structure. The ends of the metal layers of both piezoelectric conversion structures that are close to the mass block are grounded, and the other ends of the metal layers of both piezoelectric conversion structures that are furthest from the mass block output a voltage signal.

[0042] In a specific embodiment, the planar shape of the mass block can be rectangular, square, circular, or a regular polygon. The coil is a planar helical coil, and the planar shape of each turn of the planar helical coil can be rectangular, square, circular, or a regular polygon. The shape of the elastic beam can be selected from various types, such as a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam. The piezoelectric material of the piezoelectric material layer in the piezoelectric conversion structure can be one or more of AlN, ScAlN, PZT, ZnO, and PVDF. The material of the metal layer in the piezoelectric conversion structure can be one or more of Pt, Mo, Al, Au, Cu, Ti, Cr, and Ag.

[0043] Typically, current sensors (chips) are powered by a chip power supply or a battery, which is usually direct current (DC), such as DC voltage or DC current. When DC current is applied to the ends of a planar helical coil, the coil generates a magnetic field due to the magnetoelectric effect. The direction and magnitude of this magnetic field are constant; it is not an alternating magnetic field. When there is a current-carrying wire (the object being measured) above the current sensor chip, there are two cases:

[0044] The first scenario: If the conductor carries direct current (DC), a magnetic field is generated around it. The magnetic flux through the planar helical coil does not change over time, and the planar helical coil exhibits no electromagnetic induction, meaning there is no induced current. Therefore, the current sensor chip cannot detect the DC current in the conductor. However, when a voltage is applied to the upper and lower metal layers of the "sandwich" piezoelectric conversion structure (metal layer-piezoelectric material layer-metal layer), the structure undergoes bending deformation (mechanical deformation) due to the inverse piezoelectric effect. This bending deformation causes the underlying elastic beam to buckle, displacing the mass block and the planar helical coil on its surface. Due to the buckling recovery effect of the elastic beam, the mass block moves the planar helical coil up and down. When the conductor carries DC current, the magnetic flux through the moving planar helical coil changes, inducing a current at both ends of the coil. By measuring this induced current, the magnitude of the DC current in the conductor can be detected. In this case, the current sensor chip's DC current detection mode is based on the magnetoelectric effect-inverse piezoelectric effect.

[0045] The second scenario: If the current-carrying conductor is carrying alternating current (AC), an alternating magnetic field is generated around it. When a voltage or current is applied to the two ends of the planar helical coil, the magnetic field generated by the planar helical coil interacts with the alternating magnetic field around the AC conductor through attraction and repulsion. Under the periodic attraction and repulsion, the planar helical coil causes the mass block to move up and down, thus causing the elastic beam to buckle. The buckling deformation of the elastic beam leads to the buckling deformation of the "sandwich" piezoelectric conversion structure of the metal layer-piezoelectric material layer-metal layer. Due to the positive piezoelectric effect, polarization occurs inside the piezoelectric material layer in the middle layer, and opposite charges appear on the upper and lower opposing surfaces of the piezoelectric material layer. This creates a voltage difference between the upper and lower metal layers, resulting in a voltage signal output. By measuring this voltage signal, the magnitude of the AC current in the current-carrying conductor can be detected. In this case, the current sensor chip's operation mode for detecting AC current is based on the magnetoelectric effect-positive piezoelectric effect.

[0046] The current sensor chip operates in two modes: a magnetoelectric effect-direct piezoelectric effect mode and a magnetoelectric effect-inverse piezoelectric effect mode, i.e., a bidirectional magnetoelectric effect-piezoelectric effect mode. Therefore, by selecting the bidirectional magnetoelectric effect-piezoelectric effect mode, this current sensor chip can detect both direct current and alternating current.

[0047] This invention combines the magnetoelectric and piezoelectric effects to provide a current sensor chip structure based on these effects. By selecting either a magnetoelectric-direct piezoelectric effect or a magnetoelectric-inverse piezoelectric effect operating mode, a single current sensor can simultaneously detect both DC and AC currents, making it applicable to various current detection scenarios. The chip structure design employs a single coil, a single mass block, a set of elastic beams, and a set of piezoelectric conversion structures. Compared to traditional complex assembly structures based on magnetoelectric effects, this design is easier to manufacture using MEMS micromachining technology, enabling integrated and mass production, reducing production costs, and offering significant advantages for large-scale applications in various current detection scenarios.

[0048] The aforementioned current sensor based on the magnetoelectric and piezoelectric effects can be used in both direct current (DC) and alternating current (AC) environments. In DC applications, the current sensor operates in DC detection mode. In DC detection mode, voltage or current is applied to the first and second metal layers of the piezoelectric conversion structure, and DC detection is achieved by measuring the induced current in the coil. In AC applications, the current sensor operates in AC detection mode. In AC detection mode, DC current flows through the coil, and AC detection is achieved by measuring the voltage between the first and second metal layers of the piezoelectric conversion structure.

[0049] The present invention also provides a chip, which includes the current sensor based on the magnetoelectric effect and piezoelectric effect described in the above embodiments.

[0050] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. As long as such combination does not violate the spirit of the embodiments of the present invention, it should also be considered as the content disclosed by the embodiments of the present invention.

Claims

1. A current sensor based on the magnetoelectric effect and piezoelectric effect, characterized in that, include: Support structure, mass block, coil, elastic beam, and piezoelectric conversion structure disposed on the surface of elastic beam; The mass block is connected to the elastic beam, the mass block is suspended above the support structure, and the coil is disposed on the surface of the mass block; The piezoelectric conversion structure includes a first metal layer, a piezoelectric material layer, and a second metal layer, wherein the piezoelectric material layer is disposed between the first metal layer and the second metal layer. When the first metal layer and the second metal layer are subjected to voltage, the piezoelectric conversion structure deforms under the inverse piezoelectric effect of the piezoelectric material layer, causing the elastic beam to deform and the mass block and coil to move. The coil generates an induced current under the action of the magnetic field generated by the DC current being measured. The DC current being measured is detected by measuring the induced current of the coil.

2. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, The coil generates a magnetic field when a direct current is applied. The magnetic field generated by the coil interacts with the alternating magnetic field generated by the alternating current being measured, causing the mass block to move. The elastic beam deforms as the mass block moves, causing the piezoelectric conversion structure to deform. Under the positive piezoelectric effect, a voltage signal is generated between the first metal layer and the second metal layer. The AC current being measured is detected by measuring the voltage signal.

3. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, The surface of the support structure has a cavity, and the mass block is located above the cavity.

4. The current sensor based on magnetoelectric and piezoelectric effects according to claim 3, characterized in that, The elastic beam includes a first elastic beam and a second elastic beam. The first end of the first elastic beam and the first end of the second elastic beam are respectively fixed to the two ends of the support structure, and the second end of the first elastic beam and the second end of the second elastic beam are respectively connected to the two ends of the mass block.

5. The current sensor based on magnetoelectric and piezoelectric effects according to claim 4, characterized in that, The mass block is centrally symmetrical in shape, with symmetrical ends; The first elastic beam and the second elastic beam are connected to the symmetrical ends of the mass block.

6. The current sensor based on magnetoelectric and piezoelectric effects according to claim 5, characterized in that, The mass block has a planar shape that is rectangular, square, circular, or a regular polygon.

7. The current sensor based on magnetoelectric and piezoelectric effects according to claim 5, characterized in that, The coil is a planar spiral coil, and the planar shape of each turn of the coil in the planar spiral coil is a rectangle, square, circle or regular polygon.

8. The current sensor based on magnetoelectric and piezoelectric effects according to claim 4, characterized in that, The elastic beam can be a straight beam, a folded beam, a double-folded beam, a spiral beam, a crab-shaped beam, or a serpentine beam.

9. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, The first metal layer is located on the surface of the elastic beam, the piezoelectric material layer is located on the surface of the first metal layer, and the second metal layer is located on the surface of the piezoelectric material layer.

10. The current sensor based on magnetoelectric and piezoelectric effects according to claim 4, characterized in that, The piezoelectric conversion structure includes a first piezoelectric conversion structure and a second piezoelectric conversion structure. The first piezoelectric conversion structure is disposed on the surface of the first elastic beam, and the second piezoelectric conversion structure is disposed on the surface of the second elastic beam. The metal layers of the first and second piezoelectric conversion structures are grounded at the ends of the mass block.

11. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, The piezoelectric material of the piezoelectric material layer is at least one of AlN, ScAlN, PZT, ZnO, and PVDF.

12. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, The materials of the first metal layer and the second metal layer are at least one of Pt, Mo, Al, Au, Cu, Ti, Cr, and Ag.

13. The current sensor based on magnetoelectric and piezoelectric effects according to claim 1, characterized in that, In DC applications, the current sensor operates in DC detection mode. In DC detection mode, voltage or current is applied to the first and second metal layers of the piezoelectric conversion structure, and DC detection is achieved by measuring the induced current of the coil. In an AC power application environment, the current sensor operates in AC detection mode. In AC detection mode, the coil is energized with DC power, and AC detection is achieved by measuring the voltage between the first and second metal layers of the piezoelectric conversion structure.

14. A chip, characterized in that, The chip includes a current sensor based on magnetoelectric and piezoelectric effects as described in any one of claims 1-13.

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