Giant magnetoresistance current sensor with flexible magnetic ring

Abstract

The invention discloses a giant magnetoresistance current sensor with a flexible magnetic ring, relates to the technical field of current sensors, and is used for solving the problem that an existing giant magnetoresistance current sensor cannot be attached to a complex surface or embedded into flexible electronic equipment. Comprising a giant magnetoresistance chip, a flexible magnetic ring, a signal processing PCB, a signal processing circuit and a flexible magnetic core, the two ends of the flexible magnetic ring are connected with the corresponding ends of the giant magnetoresistance chip, the flexible magnetic core is located in the flexible magnetic ring, the giant magnetoresistance chip and the signal processing circuit are both integrated on the signal processing PCB, and the signal processing circuit is connected with the signal processing PCB. The signal processing circuit is electrically connected with the giant magnetoresistance chip and the flexible magnetic ring; the giant magnetoresistance chip is used for sensing the change of a magnetic field, the change of the magnetic field generated when current flows through a wire to be detected is detected by the giant magnetoresistance chip and is converted into an electric signal, and the signal processing circuit is used for amplifying and denoising the detected electric signal and then outputting the electric signal. According to the invention, the requirements of fitting a complex surface or embedding a flexible electronic device can be met.

Description

Technical Field

[0001] The invention relates to the technical field of current sensors, in particular to a giant magnetoresistance current sensor with a flexible magnetic ring. Background Art

[0002] Giant magnetoresistance current sensor is an advanced sensor technology based on giant magnetoresistance effect, which is widely used in the occasions of accurate current measurement. Giant magnetoresistance effect is a quantum mechanical phenomenon that occurs in a multilayer thin film structure composed of alternating ferromagnetic and non-ferromagnetic layers. When an external magnetic field acts on this structure, the resistance of the film changes significantly, and the change in resistance can be used to detect the change in magnetic field caused by the current passing through, thereby realizing current measurement. Giant magnetoresistance current sensor has been widely used in power systems, automotive electronics, industrial automation and consumer electronics due to its advantages such as high sensitivity, wide bandwidth, small size and low power consumption. However, traditional giant magnetoresistance current sensors usually use rigid coils, which limits their applicability in some special applications. For example, when the sensor needs to be attached to a complex surface or embedded in a flexible electronic device, the rigid coil cannot provide the required flexibility and adaptability. Therefore, the development of a giant magnetoresistance current sensor with a flexible coil can better meet these application requirements. Summary of the invention

[0003] The purpose of the present invention is to provide a giant magnetoresistive current sensor with a flexible magnetic ring, which is used to solve the problem that the existing giant magnetoresistive current sensor cannot provide the required flexibility due to the use of rigid coils, and thus cannot meet the requirements of fitting complex surfaces or being embedded in flexible electronic devices.

[0004] The technical solution adopted by the present invention to solve its technical problem is: a giant magnetoresistance current sensor with a flexible magnetic ring, comprising a giant magnetoresistance chip, a flexible magnetic ring, a signal processing PCB board, a signal processing circuit and a flexible magnetic core, the two ends of the flexible magnetic ring are connected to the corresponding ends of the giant magnetoresistance chip, the flexible magnetic core is located inside the flexible magnetic ring, the giant magnetoresistance chip and the signal processing circuit are both integrated on the signal processing PCB board, and the signal processing circuit is electrically connected to the giant magnetoresistance chip and the flexible magnetic ring; the giant magnetoresistance chip is used to sense changes in the magnetic field, and the changes in the magnetic field generated when the current flows through the conductor to be measured are detected by the giant magnetoresistance chip and converted into electrical signals, and the signal processing circuit amplifies and denoises the detected electrical signals and then outputs them.

[0005] Furthermore, the signal processing circuit is designed using an integrated circuit, including an amplifier, a filter, an analog-to-digital converter and a microcontroller, and the signal is processed and output by the microcontroller.

[0006] Furthermore, the flexible magnetic ring includes an upper FPC circuit board and a lower FPC circuit board arranged one above the other, the bottom surface of the upper FPC circuit board and the top surface of the lower FPC circuit board both have FPC coils, and the FPC coils on the bottom surface of the upper FPC circuit board and the top surface of the lower FPC circuit board are electrically connected, and the flexible magnetic core is located between the two FPC coils.

[0007] Furthermore, the flexible magnetic core is a double-layer structure, including upper and lower layers of amorphous alloy magnetic cores.

[0008] Furthermore, a frame is bonded to the bottom surface of the lower FPC circuit board.

[0009] Furthermore, the FPC coil is obtained by copper printing, or by winding a coil around a magnetic core.

[0010] Furthermore, one end of the flexible magnetic ring has a ZIF connector, and one end of the upper FPC circuit board and one end of the lower FPC circuit board are fixedly connected via the ZIF connector.

[0011] Furthermore, the other end of the flexible magnetic ring is connected to the signal processing PCB board through an I-shaped clamp.

[0012] Furthermore, the signal processing PCB board is made of FR-4 material.

[0013] Furthermore, the ZIF connector is a drawer-type plug-and-unplug structure.

[0014] The beneficial effects of the present invention are as follows: the present invention provides a giant magnetoresistance current sensor with a flexible coil. When the electromagnetic induction generated by the primary current passes through the flexible magnetic ring, the giant magnetoresistance chip can sense the change in the magnetic field and convert it into a voltage signal, which is amplified and filtered by the signal processing circuit to finally output an accurate monitoring value. Due to the design of the flexible magnetic ring, the stability and accuracy of the measurement can be maintained even when applied on complex surfaces or in a small space. In addition, when measuring the current of a current-carrying conductor, the present invention can be directly sleeved on the outside of the conductor. The conductor can be located at any position in the giant magnetoresistance current sensor or form any angle with it, which can ensure accurate measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the top view structure of the present invention; Figure 2 It is a side view structural diagram of a flexible magnetic ring including an FPC coil obtained by FPC printing, a giant magnetoresistance chip and a signal processing PCB board; Figure 3 It is a side view structural diagram of a flexible magnetic ring including an FPC coil obtained by directly winding a coil around a magnetic core, a giant magnetoresistance chip, and a signal processing PCB board; Figure 4 It is a structural schematic diagram of an I-shaped clamp; Figure 5 It is a schematic diagram of the composition structure of the flexible magnetic ring; Figure 6 It is a schematic diagram of the interface between the lower FPC circuit board and the upper FPC circuit board; Figure 7 A three-dimensional diagram of the state of use for the present invention; Figure 8 This is one of the modeling simulation schematic diagrams of the present invention; Fig. 9 This is the second schematic diagram of modeling simulation of the present invention; Fig.10 It is a curve diagram showing the change of magnetic field at the observation point with the change of primary current; In the figure: 1 giant magnetoresistance chip, 2 flexible magnetic ring, 21 ZIF connector, 22 lower FPC circuit board, 23 I-shaped clamp, 231 flexible magnetic core clamp, 232 PCB board clamp, 24 upper FPC circuit board, 25 teardrop-shaped interface, 26 FPC coil, 27 skeleton, 3 signal processing PCB board, 4 signal processing circuit, 5 flexible magnetic core, 51 upper amorphous alloy core, 52 lower amorphous alloy core, 6 wire to be tested. DETAILED DESCRIPTION

[0016] like Figure 1 As shown, a giant magnetoresistance current sensor with a flexible coil includes a giant magnetoresistance chip 1, a flexible magnetic ring 2, a signal processing PCB board 3, a signal processing circuit 4 and a flexible magnetic core 5. The ends of the flexible magnetic ring 2 are respectively fixed to the corresponding ends of the giant magnetoresistance chip 1. The giant magnetoresistance chip 1 and the signal processing circuit 4 are integrated on the signal processing PCB board 3. The giant magnetoresistance chip 1 is used to sense the change of the magnetic field. When the current flows through the conductor, the magnetic field change generated is detected by the giant magnetoresistance effect on the giant magnetoresistance chip 1 and converted into an electrical signal. The signal processing PCB board 3 is made of FR-4 material. FR-4 is a commonly used glass fiber reinforced epoxy resin with excellent mechanical strength and electrical insulation properties.

[0017] like Figure 2 , Figure 3 and Figure 5 As shown, the flexible magnetic ring 2 includes a ZIF connector 21, a lower FPC circuit board 22, an I-shaped clip 23, an upper FPC circuit board 24, an FPC coil 26 and a frame 27. The ZIF connector 21 has a free plug-in structure and is a drawer-type connection method. Figure 2 As shown, the FPC coil 26 can be realized by printing copper on the FPC, such as Figure 3As shown, the FPC coil 26 can also be obtained by directly surrounding the flexible magnetic core 5 with a coil. The FPC coil 26 is connected to the signal processing PCB board 3 through the ZIF connector 21. The plug-in structure of the ZIF connector 21 makes the entire giant magnetoresistive current sensor an open-loop structure, which is convenient for operation and use. Figure 4 As shown, the I-shaped clamp 23 includes a flexible magnetic core clamp 231 and a PCB board clamp 232. The flexible magnetic core clamp 231 is used to clamp the flexible magnetic ring 2, and the PCB board clamp 232 is used to clamp the signal processing PCB board 3, and then the connection between the flexible magnetic ring 2 and the signal processing PCB board 3 is realized through the I-shaped clamp 23. And the I-shaped clamp 23 cooperates with the ZIF connector 21, so that the head and tail ends of the flexible magnetic ring 2 are respectively fixedly connected to the two ends of the giant magnetoresistive chip 1. That is, the head end of the flexible magnetic ring 2 is connected to one end of the giant magnetoresistive chip 1 through the I-shaped clamp 23, and the end of the flexible magnetic ring 2 is connected to the other end of the giant magnetoresistive chip 1 through the ZIF connector 21.

[0018] like Figure 5 As shown, the lower FPC circuit board 22 and the upper FPC circuit board 24 have the same shape and size, and both the lower FPC circuit board 22 and the upper FPC circuit board 24 have FPC coils 26. The upper FPC circuit board 24 and the lower FPC circuit board 22 are stacked up and down, and the long sides of the upper FPC circuit board 24 and the lower FPC circuit board 22 are connected by a hot pressing process, so that the FPC coils 26 are turned on; at this time, as shown in FIG. Figure 6 As shown, the solder paste at the interface of the upper FPC circuit board 24 and the lower FPC circuit board 22 melts to form a water drop-shaped interface 25. One end of the FPC coil 26 is connected to the ZIF connector 21, and the ZIF connector 21 is plug-in connected to the signal processing PCB board 3, thereby connecting the FPC coil 26 to the signal processing PCB board 3.

[0019] In order to make the giant magnetoresistance current sensor less likely to deform in a bent state, the flexible magnetic ring 2 also includes a skeleton 27. The skeleton 27 is made of a flexible insulating material epoxy resin. The epoxy resin has good insulation properties and mechanical strength and can provide support in a bent state. The skeleton 27 is set on the bottom surface of the flexible magnetic ring 2, that is, the bottom surface of the lower FPC circuit board 22, and the lower FPC circuit board 22 and the skeleton 27 are bonded and fixed with an adhesive. The adhesive can ensure the close connection between the skeleton 27 and the flexible magnetic ring 2, and improve the stability of the structure of the flexible magnetic ring 2. The setting of the skeleton 27 is also convenient for fixing the position of the flexible magnetic ring 2 to avoid the instability of the measurement data caused by the movement of the flexible magnetic ring 2. The skeleton 27 can also enhance the mechanical strength of the entire giant magnetoresistance current sensor and improve durability.

[0020] like Figure 5As shown, the flexible magnetic core 5 includes two pieces of flexible amorphous alloys with high magnetic permeability, namely an upper amorphous alloy core 51 and a lower amorphous alloy core 52. The flexible amorphous alloy has high magnetic permeability and good flexibility, and can maintain stable magnetic properties in a bent state. The upper amorphous alloy core 51 and the lower amorphous alloy core 52 are adhered together by an adhesive, and the upper amorphous alloy core 51 and the lower amorphous alloy core 52 are clamped between the lower FPC circuit board 22 and the FPC coil 26 on the upper FPC circuit board 24 to form a current sensor magnetic ring, which can concentrate the magnetic field and improve the sensitivity and accuracy of the detection. The flexible magnetic core 5 is clamped in the FPC coil 26 to form a flexible magnetic ring structure. The ends of the upper amorphous alloy core 51 and the lower amorphous alloy core 52 extend out of the FPC coil 26, and the other major parts of the upper amorphous alloy core 51 and the lower amorphous alloy core 52 are located between the two FPC coils 26, and also between the lower FPC circuit board 22 and the upper FPC circuit board 24. The head end of the flexible magnetic ring 2 is fixed by a ZIF connector 21, and the end is fixed together by an I-shaped clip 23, which is specifically connected to the flexible magnetic core clamp 231.

[0021] Most of the flexible magnetic core 5 is located between the lower FPC circuit board 22 and the upper FPC circuit board 24. The flexible magnetic core 5 is fixed between the lower FPC circuit board 22 and the upper FPC circuit board 24 to form a conductive loop by utilizing the flexible characteristics of the flexible magnetic core 5 and the FPC coil 26, thereby forming a negative feedback system. The FPC coil 26 on the lower FPC circuit board 22 and the upper FPC circuit board 24 conducts current to form a complete circuit.

[0022] like Figure 1 As shown, the signal processing circuit 4 adopts an integrated circuit design, connects the giant magnetoresistance chip 1 and the flexible magnetic ring 2, and the amplifier, filter and sampling resistor are integrated on the signal processing PCB board 3. The giant magnetoresistance chip 1 converts the magnetic field gathered by the flexible magnetic ring 2 into a voltage output. Since the voltage value is very small, the signal processing circuit 4 is required to amplify it, and then filter and output the signal to ensure the accuracy and stability of the signal. Specifically: the signal processing circuit 4 is used to amplify the weak electrical signal output by the giant magnetoresistance chip 1. The amplifier of the signal processing circuit 4 can increase the strength of the electrical signal to make it suitable for subsequent processing. The filter selectively allows signals of certain frequencies to pass through and blocks signals of other frequencies, thereby improving the purity of the signal and removing noise and interference in the signal. The amplified analog signal is converted into a digital signal, which is convenient for the microcontroller to process and output, ensuring the accuracy and consistency of the signal. The microcontroller further processes the digital signal, such as calibration and compensation, and finally outputs an accurate monitoring value.

[0023] like Figure 8 , Fig. 9As shown, an observation point is established at the center of the air gap of the flexible magnetic core 5 to simulate the magnetic induction intensity induced by the giant magnetoresistive chip 1, and a current range of 0-300A and a step length of 50 are set. Fig.10 It can be seen that the magnetic induction intensity at the observation point increases linearly with the increase of the primary current, thus proving the ideal magnetic concentrating structure of the FPC coil 26 designed by the present invention. When the primary current is 300A, the magnetic induction intensity at the observation point is 0.02T, which is less than the saturation magnetic induction intensity of the flexible amorphous alloy, 1.5T, so the current bandwidth detectable by the present invention can be widened.

[0024] like Figure 7 As shown, the giant magnetoresistance current sensor provided by the present invention can be directly mounted on the outside of the conductor 6 to be measured when measuring the current of a current-carrying conductor. Regardless of the conductor 6 to be measured being located at any position in the giant magnetoresistance current sensor or forming any angle with the conductor 6, the measurement result can be ensured to be accurate. The giant magnetoresistance current sensor provided by the present invention is simple in structure, easy to operate and has accurate measurement, and is particularly suitable for applications on complex surfaces or in narrow spaces. Through the flexible magnetic ring 2 and the precise signal processing circuit 4, the giant magnetoresistance current sensor of the present invention can provide stable and reliable measurement results in various application environments.

Claims

1. A giant magnetoresistance current sensor with a flexible magnetic ring, characterized in that: It includes a giant magnetoresistance chip, a flexible magnetic ring, a signal processing PCB board, a signal processing circuit and a flexible magnetic core. The two ends of the flexible magnetic ring are connected to the corresponding ends of the giant magnetoresistance chip, the flexible magnetic core is located inside the flexible magnetic ring, the giant magnetoresistance chip and the signal processing circuit are integrated on the signal processing PCB board, and the signal processing circuit is electrically connected to the giant magnetoresistance chip and the flexible magnetic ring; the giant magnetoresistance chip is used to sense changes in the magnetic field, and the magnetic field changes generated when the current flows through the conductor to be tested are detected by the giant magnetoresistance chip and converted into electrical signals, and the signal processing circuit amplifies and denoises the detected electrical signals and then outputs them.

2. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: The signal processing circuit is designed by integrated circuit, including an amplifier, a filter, an analog-to-digital converter and a microcontroller, and the signal is processed and outputted by the microcontroller.

3. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: The flexible magnetic ring includes an upper FPC circuit board and a lower FPC circuit board arranged one above the other. The bottom surface of the upper FPC circuit board and the top surface of the lower FPC circuit board both have FPC coils, and the FPC coils on the bottom surface of the upper FPC circuit board and the top surface of the lower FPC circuit board are electrically connected, and the flexible magnetic core is located between the two FPC coils.

4. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 3, characterized in that: The flexible magnetic core is a double-layer structure, including upper and lower layers of amorphous alloy magnetic cores.

5. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 4, characterized in that: The bottom surface of the lower FPC circuit board is bonded with a frame.

6. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: The FPC coil is obtained by copper printing or by winding a coil around a magnetic core.

7. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: One end of the flexible magnetic ring is provided with a ZIF connector, and one end of the upper FPC circuit board and one end of the lower FPC circuit board are fixedly connected via the ZIF connector.

8. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 7, characterized in that: The other end of the flexible magnetic ring is connected to the signal processing PCB board through an I-shaped clamp.

9. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: The signal processing PCB board is made of FR-4 material.

10. The giant magnetoresistance current sensor with a flexible magnetic ring according to claim 1, characterized in that: The ZIF connector is a drawer-type plug-and-unplug structure.

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