Giant magneto-impedance probe for double-peak sampling and GMI sensor

Abstract

The invention relates to a double-peak sampling giant magneto-impedance probe and a GMI sensor, which are characterized in that two groups of same-direction induction coils are arranged on an amorphous wire to be respectively connected to two diode detection circuits for detection, so that one of the two groups of same-direction induction coils can be responsible for realizing detection of positive peak waves, and the other one can be responsible for realizing detection of negative peak waves; therefore, support for positive and negative double-peak detection is realized, finally, the sensitivity of the applied soft magnetic amorphous wire giant magneto-impedance effect-based sensor is greatly improved, and the sensor is ensured to always work stably.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic detection sensors and relates to a double-peak sampling giant magneto-impedance probe and a GMI sensor. Background Art

[0002] The giant magneto-impedance effect refers to the fact that when a small alternating current is applied to a special soft magnetic material (such as CoFeSiB amorphous wire), the AC impedance of the material will change greatly with the change of the external magnetic field. Sensors based on the giant magneto-impedance effect can detect weak magnetic field changes, such as magnetic fields with intensities of pico-Tesla (pT) to nano-Tesla (nT). At present, the general working principle of the giant magneto-impedance sensor circuit is: high-frequency pulse voltage excitation is applied to both ends of the amorphous wire material, a set of induction coils are used to cover the amorphous wire material, and an output voltage is generated through electromagnetic induction. When the pulse generates rising edge excitation, a positive induction spike wave is generated in the induction coil, and when the pulse generates falling edge excitation, a negative induction spike wave is generated in the induction coil.

[0003] According to the giant magneto-impedance principle, when the magnetic field in the space where the amorphous wire material is located changes, the impedance of the material will change. This change in impedance will affect the magnitude of the current passing through the amorphous wire, and ultimately the amplitude of the spike wave will be reflected in the induction coil. However, the traditional detection circuit (or other forms of detection circuit) based on the giant magneto-impedance effect (GMI) sensor of soft magnetic amorphous wire detects the positive spike wave in the induction coil, but does not detect the negative spike wave in the induction coil, thus losing the information of the negative spike wave and causing a significant decrease in the sensitivity of the sensor. Summary of the invention

[0004] In view of the above problems, the present invention proposes a double-peak sampling giant magnetoimpedance probe and a GMI sensor, which can greatly improve the sensitivity of the giant magnetoimpedance effect sensor based on soft magnetic amorphous wire.

[0005] In order to achieve the above objectives, the embodiments of the present invention adopt the following technical solutions: In one aspect, a double-peak sampling giant magneto-impedance probe is provided, comprising an amorphous wire, a first induction coil and a second induction coil; The first induction coil and the second induction coil are spirally wound around the amorphous wire in the same direction along the length direction of the amorphous wire, one end of the first induction coil is used to connect to the input end of the first diode detection circuit, the other end of the first induction coil is grounded, one end of the second induction coil is grounded, and the other end of the second induction coil is used to connect to the input end of the second diode detection circuit; The positive peak wave of the first induction coil is detected by the first diode detection circuit, and the negative peak wave of the second induction coil is detected by the second diode detection circuit.

[0006] On the other hand, there is also provided a GMI sensor, comprising an amorphous wire, a first induction coil, a second induction coil, a first diode detection circuit, a second diode detection circuit, an inverting follower, an instrumentation amplifier, and an analog-to-digital converter; The first induction coil and the second induction coil are spirally wound around the amorphous wire in the same direction along the length direction of the amorphous wire, one end of the first induction coil is connected to the input end of the first diode detection circuit, the other end of the first induction coil is grounded, the output end of the first diode detection circuit is connected to the first input end of the instrumentation amplifier, one end of the second induction coil is grounded, the other end of the second induction coil is connected to the input end of the second diode detection circuit, the output end of the second diode detection circuit is connected to the inverting input end of the inverting follower, the output end of the inverting follower is connected to the second input end of the instrumentation amplifier, the output end of the inverting follower is connected to the non-inverting input end, and the output end of the instrumentation amplifier is connected to the analog-to-digital converter; The first diode detection circuit is used to perform positive spike wave detection on the first induction coil, the second diode detection circuit and the inverting follower are used to perform negative spike wave detection on the second induction coil, and the instrument amplifier is used to amplify the output of the first diode detection circuit and the inverting follower and send it to the analog-to-digital converter for sampling.

[0007] The above technical solution has the following advantages and beneficial effects: The above-mentioned dual-peak sampling giant magnetoimpedance probe and GMI sensor, by placing two sets of unidirectional induction coils on the amorphous wire and connecting them to two diode detection circuits for detection respectively, can make one of them responsible for detecting the positive spike wave and the other responsible for detecting the negative spike wave, thereby supporting positive and negative dual-peak detection, and ultimately greatly improving the sensitivity of the soft magnetic amorphous wire-based giant magnetoimpedance effect sensor and ensuring that the sensor can always maintain stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0009] Figure 1 It is a schematic diagram of the circuit structure of an existing soft magnetic amorphous wire giant magnetoimpedance effect sensor; Figure 2 This is a schematic diagram of the basic principle of the giant magneto-impedance probe; Figure 3It is a schematic diagram of the circuit structure of a giant magneto-impedance probe for double peak sampling in one embodiment; Figure 4 It is a schematic diagram of the physical structure of a giant magneto-impedance probe for double peak sampling in one embodiment; Figure 5 Schematic diagram of the circuit structure of a GMI sensor in one embodiment; Figure 6 FIG. 4 is a schematic diagram of the circuit structure of a GMI sensor in another embodiment. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and Examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0011] It should be noted that the reference to "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The presentation of this phrase at various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It will be appreciated by those skilled in the art that the embodiments described herein may be combined with other embodiments. The term "and / or" used in the specification of the present invention and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0012] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0013] Existing sensors based on the giant magneto-impedance effect of soft magnetic amorphous wire mostly use diode detection methods, such as Figure 1 As shown, represents the alternating excitation current, It indicates the excitation magnetic field generated by the excitation current flowing in the amorphous wire (i.e. GIM element) along the length direction. The diode detection circuit consists of a detection diode D 1. Sampling capacitor C 1 and discharge resistor R 1. When the induction coil L The voltage across the detector diode exceeds D 1 cut-off voltage and in the rising stage, the detector diode D 1 conduction, induction coil LContinuously feed the sampling capacitor C 1Charge, sampling capacitor C 1Following induction coil L The output voltage of the induction coil L When the voltage at both ends passes the peak and starts to drop, due to the detection diode D 1 shows a negative voltage across both ends and is cut off. C 1 The voltage on the induction coil is always kept L The peak value of the positive wave peak. This enables the peak sampling of the spike signal. Sampling capacitor C The voltage across 1 is further sampled by the analog-to-digital converter ADC to obtain the output of the sensor. Figure 2 The following is the basic principle diagram of the giant magneto-impedance probe. Represents the induced voltage of the induction coil.

[0014] After in-depth research, it was found that the existing detection circuit (or other forms of detection circuit) based on the soft magnetic amorphous wire giant magnetoimpedance effect sensor is a detection circuit for the induction coil. L It detects the positive peak wave in the induction coil. L The negative spike wave in the amorphous wire is detected, and the information of the negative spike wave is lost. In fact, generally speaking, the change of the external magnetic field in the linear working range of the amorphous wire is consistent in the change of the amplitude of the positive spike wave and the negative spike wave, which means that if the amplitude of the positive spike wave changes by 1, the relative amplitude of the positive and negative spike waves changes by 2. The existing detection circuit based on the soft magnetic amorphous wire giant magnetoimpedance effect sensor only detects the positive spike wave and loses 1 times the sensitivity. In addition, when the external magnetic field changes or the magnetic field in the environment where the sensor is located changes, the amorphous wire deviates from the linear working area. Induction coil L The sensitivities of the positive and negative peaks are not consistent. It is possible that the positive peak has high sensitivity and the negative peak has low sensitivity, or it is possible that the positive peak has low sensitivity and the negative peak has high sensitivity. Therefore, the above-mentioned traditional technical solution that only detects the positive peak may significantly reduce the sensitivity of the sensor in some cases and cannot meet the actual use requirements.

[0015] In order to solve the problem that the aforementioned traditional technical solution only samples the positive peak in the induction coil, resulting in limited sensitivity, this specification proposes a new dual-peak sampling sensor solution to further improve the sensitivity of the sensor and ensure that the sensor can always maintain stable operation.

[0016] In one embodiment, Figure 3As shown, a double-peak sampling giant magneto-impedance probe 100 is provided, comprising an amorphous wire G0, a first induction coil L01 and a second induction coil L02. The first induction coil L01 and the second induction coil L02 are spirally wound around the amorphous wire G0 in the same direction along the length direction of the amorphous wire G0. One end of the first induction coil L01 is used to connect to the input end of the first diode detection circuit 102, and the other end of the first induction coil L01 is grounded. One end of the second induction coil L02 is grounded, and the other end of the second induction coil L02 is used to connect to the input end of the second diode detection circuit 104. The positive spike wave of the first induction coil L01 is detected by the first diode detection circuit 102. The negative spike wave of the second induction coil L02 is detected by the second diode detection circuit 104.

[0017] It can be understood that the first diode detection circuit 102 and the second diode detection circuit 104 can both adopt existing diode detection circuit structures in the art, such as Figure 3 As shown in the figure, the first diode detection circuit 102 can be composed of a detection diode D01, a sampling capacitor C01 and a discharge resistor R01, and the second diode detection circuit 104 can be composed of a detection diode D02, a sampling capacitor C02 and a discharge resistor R02, which are respectively responsible for the detection processing of the positive peak wave and the detection processing of the negative peak wave. The output results of the detection can be sent to the subsequent circuit for processing, so as to be finally sent to the analog-to-digital converter ADC for sampling.

[0018] In this embodiment, two groups of induction coils in the same direction (i.e., the first induction coil L01 and the second induction coil L02) are arranged on the amorphous wire G0, wherein the output end of the other end of the first induction coil L01 (i.e., the end of the first induction coil L01 close to the N side of the amorphous wire G0) is grounded. One end of the first induction coil L01 (i.e., the end of the first induction coil L01 close to the P side of the amorphous wire G0) is connected to the first diode detection circuit 102 as an output end, which is responsible for positive peak value (i.e., the peak value of the positive spike wave) detection. One end of the second induction coil L02 (i.e., the end of the second induction coil L02 close to the P side of the amorphous wire G0) is grounded as an output end, and the other end of the second induction coil L02 (i.e., the end of the second induction coil L02 close to the N side of the amorphous wire G0) is connected to the second diode detection circuit 104 as an output end, which is responsible for negative peak value (i.e., the peak value of the negative spike wave) detection. The output results of the two detections can be sent to the subsequent circuit for processing.

[0019] Specifically, when an excitation current is applied to the amorphous wire G0, a positive spike wave and a negative spike wave will be output on the induction coil. In order to sample the positive peak and negative peak on the induction coil, two sets of induction coils are wound in the same direction on the amorphous wire G0, namely the first induction coil L01 and the second induction coil L02. The N end of the first induction coil L01 is grounded. Figure 3 After the signal at point A passes through the first diode detection circuit 102, due to the unidirectional conduction characteristics of the diode in the first diode detection circuit 102, the peak value obtained by sampling the signal at point A is the peak value of the positive spike wave, that is, the output result corresponding to point C is the positive peak value.

[0020] The P terminal of the second induction coil L02 is grounded. Figure 3 When measuring at point B, its voltage waveform has the same shape as the voltage waveform of the first induction coil L01 at point A, but the voltage value is opposite, that is, the original positive voltage value is flipped to a negative voltage value, and the negative voltage value is flipped to a positive voltage value. At this time, the voltage value of the original negative peak wave is flipped to a positive voltage value. At this time, the second diode detection circuit 104 detects the original negative peak value, but the voltage value actually detected at this time is a positive voltage value.

[0021] When the amorphous wire G0 receives the change of the external magnetic field, the positive peak wave and the negative peak wave both change in the direction of increasing or decreasing absolute value. Figure 3 The peak values ​​of point C and point D in the diagram increase or decrease at the same time, and the difference between them will be offset. Therefore, in practical applications, an operational amplifier can be added at point D to form an inverting follower, so that the output signal at point D can be flipped from a positive voltage value to a negative voltage value using the inverting follower, restoring the original negative peak value. Finally, the output of point C and the output of point D after the inverting follower constitute the positive and negative peak samples, which are finally sent to the differential input of the instrument amplifier for subsequent processing. Figure 4 , which is a physical schematic diagram of the giant magneto-impedance probe 100 .

[0022] The above-mentioned dual-peak sampling giant magnetoimpedance probe 100, by placing two groups of unidirectional induction coils on the amorphous wire and connecting them to two diode detection circuits for detection respectively, can make one of them responsible for detecting the positive spike wave and the other responsible for detecting the negative spike wave, thereby supporting positive and negative dual-peak detection, and ultimately greatly improving the sensitivity of the sensor used and ensuring that the sensor can always maintain stable operation.

[0023] In some embodiments, optionally, the amorphous wire G0 may be a Co-based amorphous alloy or a Fe-based amorphous alloy.

[0024] In one embodiment, Figure 5 As shown, a GMI sensor 200 is also provided, including an amorphous wire G0, a first induction coil L01, a second induction coil L02, a first diode detection circuit 102, a second diode detection circuit 104, an inverting follower 106, an instrumentation amplifier Amp and an analog-to-digital converter ADC. The first induction coil L01 and the second induction coil L02 are spirally wound around the amorphous wire G0 in the same direction along the length direction of the amorphous wire G0. One end of the first induction coil L01 is connected to the input end of the first diode detection circuit 102, and the other end of the first induction coil L01 is grounded. The output end of the first diode detection circuit 102 is connected to the first input end of the instrumentation amplifier Amp. One end of the second induction coil L02 is grounded, and the other end of the second induction coil L02 is connected to the input end of the second diode detection circuit 104. The output end of the second diode detection circuit 104 is connected to the inverting input end of the inverting follower 106, the output end of the inverting follower 106 is connected to the second input end of the instrumentation amplifier Amp, and the output end of the inverting follower 106 is connected to the non-inverting input end. The output end of the instrumentation amplifier Amp is connected to the analog-to-digital converter ADC. The first diode detection circuit 102 is used to detect the positive spike wave of the first induction coil L01. The second diode detection circuit 104 and the inverting follower 106 are used to detect the negative spike wave of the second induction coil L02. The instrumentation amplifier Amp is used to amplify the output of the first diode detection circuit 102 and the inverting follower 106 and send it to the analog-to-digital converter ADC for sampling.

[0025] It can be understood that the inverting follower 106 can be formed by various types of operational amplifiers existing in the art, as long as it can be used to provide the required output signal following flipping function, and the instrumentation amplifier Amp can be various types of instrumentation amplifiers existing in the art, as long as it can be used to provide the required detection output result amplification effect, and point E represents the output of the inverting follower 106. The analog-to-digital converter ADC can be various types of ADCs existing in the art, as long as it can be used to perform the required signal acquisition effect.

[0026] Specifically, two groups of induction coils in the same direction (i.e., the first induction coil L01 and the second induction coil L02) are arranged on the amorphous wire G0, wherein the other end of the first induction coil L01 is grounded. One end of the first induction coil L01 is connected to the first diode detection circuit 102 as an output end, which is responsible for positive peak detection. One end of the second induction coil L02 is grounded, and the other end of the second induction coil L02 is connected to the second diode detection circuit 104 as an output end. The output of the second diode detection circuit 104 is connected to the second input end of the instrumentation amplifier Amp through the inverting follower 106. The second diode detection circuit 104 and the inverting follower 106 are responsible for negative peak detection. The output results of the two detections can be sent to the instrumentation amplifier Amp for amplification and then sent to the analog-to-digital converter ADC for sampling, so as to realize the voltage collection of the first induction coil L01 and the second induction coil L02.

[0027] The above-mentioned GMI sensor 200 arranges two groups of unidirectional induction coils on the amorphous wire and connects them to two diode detection circuits for detection respectively, so that one of them can be responsible for detecting the positive spike wave and the other can be responsible for detecting the negative spike wave, thereby supporting double-peak detection in the positive and negative directions, and ultimately greatly improving the sensitivity of the giant magnetoimpedance effect sensor based on the soft magnetic amorphous wire and ensuring that the sensor can always maintain stable operation.

[0028] In one embodiment, the amorphous wire G0 is a Co-based amorphous alloy wire or a Fe-based amorphous alloy wire.

[0029] In one embodiment, the instrumentation amplifier Amp is a three-op-amp instrumentation amplifier (eg, Figure 6 As shown), an instrumentation amplifier based on the precision operational amplifier OP07, an instrumentation amplifier based on the four-op-amp integrated circuit LM324, or an instrumentation amplifier implemented by the monolithic integrated chip AD620. In this embodiment, various types of instrumentation amplifiers Amp available in the art can be used to provide the above-mentioned required detection output result amplification effect.

[0030] It can be understood that the specific explanation of the above-mentioned GMI sensor 200 can be understood by referring to the corresponding explanations in the above embodiments of the giant magneto-impedance probe 100 for double-peak sampling, and will not be repeated here.

[0031] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0032] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of protection of the invention. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A double peak sampling giant magneto-impedance probe, characterized in that: It includes an amorphous wire, a first induction coil and a second induction coil; The first induction coil and the second induction coil are spirally wound around the amorphous wire in the same direction along the length direction of the amorphous wire, one end of the first induction coil is used to connect to the input end of the first diode detection circuit, and the other end of the first induction coil is grounded, one end of the second induction coil is grounded, and the other end of the second induction coil is used to connect to the input end of the second diode detection circuit; The positive spike wave of the first induction coil is detected by the first diode detection circuit, and the negative spike wave of the second induction coil is detected by the second diode detection circuit.

2. The double peak sampling giant magneto-impedance probe according to claim 1, characterized in that: The amorphous wire is a Co-based amorphous alloy wire or a Fe-based amorphous alloy wire.

3. A GMI sensor, characterized in that: It includes an amorphous wire, a first induction coil, a second induction coil, a first diode detection circuit, a second diode detection circuit, an inverting follower, an instrument amplifier and an analog-to-digital converter; The first induction coil and the second induction coil are spirally wound around the amorphous wire in the same direction along the length direction of the amorphous wire, one end of the first induction coil is connected to the input end of the first diode detection circuit, the other end of the first induction coil is grounded, the output end of the first diode detection circuit is connected to the first input end of the instrumentation amplifier, one end of the second induction coil is grounded, the other end of the second induction coil is connected to the input end of the second diode detection circuit, the output end of the second diode detection circuit is connected to the inverting input end of the inverting follower, the output end of the inverting follower is connected to the second input end of the instrumentation amplifier, the output end of the inverting follower is connected to the non-inverting input end, and the output end of the instrumentation amplifier is connected to the analog-to-digital converter; The first diode detection circuit is used to perform positive spike wave detection on the first induction coil, the second diode detection circuit and the inverting follower are used to perform negative spike wave detection on the second induction coil, and the instrument amplifier is used to amplify the outputs of the first diode detection circuit and the inverting follower and then send them to the analog-to-digital converter for sampling.

4. The GMI sensor according to claim 3, characterized in that: The amorphous wire is a Co-based amorphous alloy wire or a Fe-based amorphous alloy wire.

5. The GMI sensor according to claim 3 or 4, characterized in that: The instrument amplifier is a three-op-amp instrument amplifier, an instrument amplifier based on the precision op-amp OP07, an instrument amplifier based on the four-op-amp integrated circuit LM324, or an instrument amplifier implemented by a monolithic integrated chip AD620.

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