Magnetic field energy-taking self-powered electromagnetic sensor and interference suppression method thereof

Abstract

The invention provides a magnetic field energy-taking self-powered electromagnetic sensor and an interference suppression method thereof, the magnetic sensor comprises a magnetic field energy-taking device, a rectification circuit, a discharge protection circuit, a micro-energy management circuit, a TMR sensing circuit and a control circuit, and the interference suppression method comprises the following steps: adjusting cable current; acquiring current excitation upper and lower limits of the sensor in three working states and TMR output values without energy-taking interference and subjected to energy-taking interference; selecting points in each section of current range to obtain a TMR output function without energy-taking interference and a TMR output function subjected to energy-taking interference, and fitting to obtain correction algorithms corresponding to the three working states; and carrying out piecewise fitting on the TMR output function subjected to energy taking interference according to a corresponding correction algorithm to obtain a cable current value after interference suppression. Through the spatial position layout of each circuit in the magnetic field energy-taking self-powered electromagnetic sensor, the interference of an alternating current magnetic field generated by magnetic field energy-taking output on magnetic sensing is reduced, and the interference suppression method can improve the precision of cable current monitoring based on magnetic sensing.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power systems, and in particular to a magnetic field energy-drawing self-powered electromagnetic sensor and an interference suppression method thereof. Background Art

[0002] Cables play a key role as the main carrier of power transmission in power transmission and distribution networks. In order to ensure the reliable and safe operation of cables, tunnel magnetoresistance sensors are needed to monitor the current in the cables. At present, such sensors are mainly powered by batteries, but due to capacity and life limitations, batteries need to be replaced regularly, which is costly and inconvenient. Therefore, an attractive and promising new power supply scheme is needed to enable TMR to achieve continuous self-powering.

[0003] At present, common power supply methods include solar energy and wind energy, vibration energy, radio frequency energy and magnetic field energy collection. Solar energy and wind energy are greatly affected by the weather, so the power supply is relatively unstable; vibration energy collection requires continuous vibration, while the cable environment is relatively stable, so it is not suitable; and vibration energy collection and radio frequency energy collection have only extremely low output power and cannot maintain the power supply of TMR sensors; in contrast, magnetic field energy collection has the advantages of simple structure, low cost and relatively stable power supply and is gradually applied to the power supply of TMR sensors.

[0004] Magnetic Energy Harvester (MEH) is a technology based on the law of electromagnetic induction that converts the magnetic field energy near the cable into electrical energy to power the TMR sensor. MEH is divided into invasive MEH and non-invasive MEH. The invasive MEH needs to clamp its magnetic core on the cable, so the size of its magnetic core needs to change according to the size of the cable cross-section, which is extremely inconvenient to install. In addition, the magnetic core of the invasive MEH is easily saturated when the cable current is hundreds of amperes, and the reliability is low. The non-invasive MEH can collect energy by simply placing it in an alternating magnetic field. The installation is convenient and flexible. In addition, the magnetic core of the non-invasive MEH is non-closed, and it is difficult to saturate even under a current of thousands of amperes. It is an effective way for TMR sensors to achieve self-powering.

[0005] The working principle of TMR is based on magnetoresistance effect and tunneling effect. The magnetization direction of the free layer changes with the external magnetic field. When the external magnetic field changes, the tunneling effect will change accordingly, which will change the size of the resistance state. The output of TMR is related to the change in the resistance value of the resistor, that is, it is related to the strength of the external magnetic field. However, when the non-invasive MEH is working, the induced current in the energy extraction coil and the current in the AC output line will generate a new magnetic field. This new magnetic field will affect the surrounding space magnetic field, causing the magnetic field strength in the near field space to change, thereby affecting the output of TMR and affecting the monitoring of the cable current.

[0006] In actual work, since the sensitive direction of TMR is consistent with the direction of magnetic flux convergence of the energy harvesting device, when a shielding device is used to weaken the interference magnetic field around the TMR, it will inevitably affect the energy harvesting effect of the energy harvesting device. At present, in order to avoid the problem of affecting the energy harvesting effect, the main method used is a compensation algorithm based on data fitting. Under the condition of fixing the relative position of the energy harvesting device and the TMR sensor, data fitting is used to form the TMR output inversion function. However, the above method does not take into account that when the current excitation changes, the TMR sensor will have different working states, and the accuracy of the formed TMR output inversion function is not high, and the reliability of cable current monitoring is low. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the present invention provides a magnetic field energy-drawing self-powered electromagnetic sensor and an interference suppression method thereof, namely, by designing a magnetic field energy-drawing self-powered TMR sensor, and establishing a spatial layout and connection relationship between various devices and circuits, the interference of magnetic field energy-drawing on magnetic sensing is reduced; by adjusting the size of the cable current, the magnetic field energy-drawing self-powered TMR sensor is in three working states, and the current excitation upper limit and lower limit of the sensor in the three working states are obtained; points are evenly distributed in each current range to obtain experimental data, and a three-segment correction algorithm is obtained based on data fitting; by judging the working states of two indicator pins output by an operating state monitoring unit, the TMR output inverse function is segmentedly corrected and fitted, and an accurate cable current value is obtained according to the TMR output voltage value.

[0008] The above technical objectives of the present invention are achieved through the following technical solutions:

[0009] The first aspect of the present invention provides a magnetic field energy-harvesting self-powered electromagnetic sensor, comprising a magnetic field energy-harvesting device, a rectifier circuit, a discharge protection circuit, a micro-energy management circuit, a TMR sensor circuit and a control circuit;

[0010] The magnetic field energy harvesting device comprises an H-shaped magnetic core and an energy harvesting coil, wherein the energy harvesting coil is wound on the H-shaped magnetic core, and the magnetic core wound with the energy harvesting coil is placed close to the single-core cable; two AC output lines connecting the coil are placed parallel to the single-core cable and close to the magnetic core;

[0011] The rectifier circuit is connected to the rear end of the magnetic field energy harvesting device, and the AC wiring inside the rectifier circuit is perpendicular to the single-core cable;

[0012] The discharge protection circuit is connected to the rear end of the rectifier circuit through two DC output lines;

[0013] The TMR sensing circuit includes a TMR chip. The TMR sensing circuit is placed in parallel and close to the top of the single-core cable, and the direction of the magnetic field generated by the single-core cable is kept parallel to the sensitive axis direction of the TMR chip. The TMR chip is placed close to the edge of the energy-taking magnetic core and the AC output line.

[0014] The micro energy management circuit includes a state monitoring unit, the micro energy management circuit is connected to the rear end of the discharge circuit, and is connected to the front end of the TMR sensor circuit and the control circuit. The rectifier circuit, the discharge circuit and the micro energy management circuit are integrated together and placed parallel to the TMR sensor circuit, and the AC wiring in the rectifier circuit is perpendicular to the magnetic sensitivity direction of the TMR sensor circuit.

[0015] The control circuit is connected to the state monitoring unit in the micro energy management circuit and is placed in parallel with the micro energy management circuit.

[0016] The second aspect of the present invention relates to an interference suppression method for a magnetic field energy self-powered electromagnetic sensor, which is used to operate the magnetic field energy self-powered electromagnetic sensor, and comprises the following steps:

[0017] Step 1: By adjusting the cable current, the magnetic field energy self-powered electromagnetic sensor is in an unsaturated state, a lightly saturated state, and a heavily saturated state, respectively, and the current excitation upper and lower limits of the sensor in the three working states and the output value of the TMR without energy extraction interference and the TMR output value with energy extraction interference are obtained;

[0018] Step 2: According to the upper and lower limits of current excitation in the unsaturated state, lightly saturated state and heavily saturated state, the output values ​​of the TMR without energy extraction interference and the TMR output values ​​with energy extraction interference in each current range are evenly distributed to obtain experimental data. Combined with the cable current, the output functions of the TMR without energy extraction interference and the TMR output functions with energy extraction interference under the three working conditions are obtained;

[0019] Step 3: Based on the output functions of the TMR without energy extraction interference in the unsaturated state, the lightly saturated state and the heavily saturated state, the output functions of the TMR with energy extraction interference in the unsaturated state, the lightly saturated state and the heavily saturated state are fitted respectively to obtain the correction algorithms corresponding to the three working states;

[0020] Step 4: Determine the working state according to the operation state monitoring unit, and fit the TMR output function affected by energy extraction interference in the unsaturated state, lightly saturated state, and heavily saturated state in sections according to the corresponding correction algorithm. Combine the corrected cable current values ​​under the three working states to obtain the cable current value after interference suppression.

[0021] Preferably, in step 1, the energy collected by the magnetic field energy harvesting device is used to power the load and charge the energy storage capacitor at the same time, but when the energy storage capacitor is not fully charged, it is in an unsaturated state;

[0022] The energy storage capacitor is fully charged and continuously supplies power to the load, but the voltage of the discharge protection circuit does not exceed the discharge voltage value, which is a light saturation state;

[0023] When the voltage of the discharge protection circuit exceeds the discharge voltage value and the discharge is started, it is in a heavy saturation state.

[0024] Preferably, the cable current is adjusted so that the magnetic field energy self-supply electromagnetic sensor operates in an unsaturated state, and the upper and lower limits of the current excitation when the sensor operates in the unsaturated state are obtained;

[0025] Adjust the cable current so that the magnetic field energy self-powered electromagnetic sensor works in a light saturation state, and obtain the current excitation upper limit and lower limit of the sensor working in the light saturation state;

[0026] The cable current is adjusted so that the magnetic field energy self-powered electromagnetic sensor operates in a heavy saturation state, and the current excitation upper limit and lower limit when the sensor operates in the heavy saturation state are obtained.

[0027] Preferably, in step 2, according to the upper and lower limits of the current excitation when the sensor operates in an unsaturated state, experimental data of the unsaturated state with and without energy extraction interference are obtained within the current range, and a relationship curve between the cable current in the unsaturated state and the TMR output with energy extraction interference and a relationship curve between the cable current in the unsaturated state and the TMR output not interfered with by energy extraction are plotted to obtain a TMR output function not interfered with by energy extraction in the unsaturated state and a TMR output function with energy extraction interference in the unsaturated state.

[0028] Preferably, in step 2, according to the upper and lower limits of the current excitation when the sensor operates in a light saturation state, experimental data of the light saturation state with and without energy extraction interference are obtained within the current range, and a relationship curve between the cable current in the light saturation state and the TMR output with energy extraction interference and a relationship curve between the cable current in the light saturation state and the TMR output not interfered with by energy extraction are plotted to obtain a TMR output function not interfered with by energy extraction in the light saturation state and a TMR output function with energy extraction interference in the light saturation state are obtained.

[0029] Preferably, in step 2, according to the upper and lower limits of the current excitation when the sensor operates in the heavily saturated state, experimental data with and without energy extraction interference in the heavily saturated state are obtained within the current range, and a relationship curve between the cable current in the heavily saturated state and the TMR output with energy extraction interference and a relationship curve between the cable current in the heavily saturated state and the TMR output not interfered with by energy extraction are plotted to obtain a TMR output function in the heavily saturated state without energy extraction interference and a TMR output function in the heavily saturated state with energy extraction interference are obtained.

[0030] Preferably, in step 3, based on the TMR output function that is not disturbed by energy extraction in an unsaturated state, a function fitting is performed on the TMR output function that is disturbed by energy extraction in an unsaturated state to obtain a correction algorithm A;

[0031] Based on the TMR output function in the light saturation state without interference from energy extraction, the TMR output function in the light saturation state with interference from energy extraction is fitted to obtain a correction algorithm B;

[0032] Based on the TMR output function in the heavily saturated state without interference from energy extraction, a function fitting is performed on the TMR output function in the heavily saturated state with interference from energy extraction to obtain a correction algorithm C.

[0033] Preferably, in step 4, the two operational comparators of the operation status monitoring unit compare the positive input voltage with the negative input voltage to monitor three working states, specifically including:

[0034] When the positive input voltage of the operational comparator 1 is less than the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the micro energy management circuit is in an unsaturated state;

[0035] When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the micro energy management circuit is in a light saturation state;

[0036] When the positive input voltage of the operational comparator 1 is ≥ the negative input voltage, and the positive input voltage of the operational comparator 2 is ≥ the negative input voltage, the micro energy management circuit is in a heavy saturation state.

[0037] Preferably, the circuit states in three working states are monitored by judging the positive input voltage and the negative input voltage of the two operational comparators of the operation state monitoring unit. The specific process includes:

[0038] When the positive input voltage of the operational comparator 1 is less than the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the energy harvesting device collects energy from the magnetic field to power the load and charge the energy storage capacitor;

[0039] When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the energy storage capacitor stops charging, and the collected energy continues to supply power to the load;

[0040] When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is greater than or equal to the negative input voltage, the voltage stabilizing diode D0 breaks down in reverse, and the discharge protection circuit starts to discharge.

[0041] Preferably, the process of piecewise fitting the TMR output inverse function according to the corresponding correction algorithm includes:

[0042] When the positive input voltage U 正1 <Negative input voltage U of operational comparator 1 负1 When , the TMR output inverse function is fitted according to the correction algorithm A, and the TMR output value is substituted into the correction algorithm A to obtain the corrected cable current value in the current working state;

[0043] When the positive input voltage U 正1 ≥Negative input voltage U of operational comparator 1 负1 , the positive input voltage U of the operational comparator 2 正2 <Negative input voltage U of computational comparator 2 负2 When , the TMR output inverse function is fitted according to the correction algorithm B, and the TMR output value is substituted into the correction algorithm B to obtain the corrected cable current value in the current working state;

[0044] When the positive input voltage U 正2 ≥Negative input voltage U of operational comparator 2 负2 When the TMR output inverse function is fitted according to the correction algorithm C, the TMR output value is substituted into the correction algorithm C to obtain the corrected cable current value in the current working state.

[0045] The beneficial effect of the present invention is that, compared with the prior art, the present invention proposes a magnetic field energy self-powered electromagnetic sensor and its interference suppression method, specifically designs a magnetic field energy self-powered TMR sensor, and establishes the spatial layout and connection relationship between each part of the device and the circuit, reduces the interference of magnetic field energy on magnetic sensing; at the same time, the three working states of the TMR sensor are considered, and a three-segment correction algorithm is obtained based on data fitting, and the TMR output inverse function is segmentedly corrected and fitted by judging the working state of the indicator pin output by the operation status monitoring unit, and the accurate cable current value is obtained according to the TMR output voltage value, so as to further improve the sensing accuracy. This magnetic field energy self-powered electromagnetic sensor and its interference suppression method can not only realize the self-powering of the TMR sensor based on magnetic field energy, but also effectively solve the problem of insufficient sensing accuracy caused by the nonlinear interference of the magnetic field energy device on the magnetic sensor due to different working states, improve the accuracy of TMR output in the magnetic field energy self-powered electromagnetic sensor, and thus improve the accuracy of cable current monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 It is a structural composition of a TMR sensor integrating magnetic field energy harvesting and magnetic sensing designed in an embodiment of the present invention;

[0048] Figure 2 It is the spatial layout and connection relationship between the various devices and circuits of the TMR sensor designed in the embodiment of the present invention;

[0049] Figure 3 It is a schematic diagram of the circuit model of the magnetic field energy harvesting device, the rectifier circuit, the discharge circuit and the micro energy management circuit in the embodiment of the present invention;

[0050] Figure 4 1 is a circuit diagram of an operation status monitoring unit of a TMR sensor designed in an embodiment of the present invention;

[0051] Figure 5 1 is a diagram of an H-type magnetic core energy harvesting device with a magnetic core size of 5cm×5cm×8cm in an embodiment of the present invention;

[0052] Figure 6 This is a TMR output segmented fitting result under the working state of the energy management circuit, considering the influence of the H-type magnetic core energy harvesting device with a magnetic core size of 5cm×5cm×8cm in the embodiment of the present invention;

[0053] Figure 7 It is the TMR output segmented fitting result under the working state 2 of the energy management circuit considering the influence of the H-type magnetic core energy harvesting device with a magnetic core size of 5cm×5cm×8cm in the embodiment of the present invention;

[0054] Figure 8 It is the TMR output segmented fitting result under the third working state of the energy management circuit, considering the influence of the H-type magnetic core energy harvesting device with a magnetic core size of 5cm×5cm×8cm in the embodiment of the present invention;

[0055] Fig. 9 It is a flow chart of the algorithm for piecewise fitting of the TMR output inverse function in an embodiment of the present invention;

[0056] Fig.10 It is a three-segment function curve of the cable current and TMR output in the embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings. The specific embodiments described here are only used to explain the present invention, but are not limited to the present invention.

[0058] Embodiment 1 of the present invention designs a magnetic field energy-harvesting self-powered TMR sensor, and establishes the spatial layout and connection relationship between each part of the device and the circuit. The magnetic field energy-harvesting self-powered TMR sensor includes a magnetic field energy-harvesting device, a rectifier circuit, a discharge protection circuit, a micro-energy management circuit, a TMR sensing circuit, and a control circuit. Figure 1 shown.

[0059] The magnetic field energy harvesting device consists of an H-shaped magnetic core and an energy harvesting coil. The energy harvesting coil is wound on the H-shaped magnetic core. The magnetic core wound with the energy harvesting coil is placed close to the top of the single-core cable. The two AC output lines connecting the coil are placed close to the magnetic core in parallel with the single-core cable.

[0060] The rectifier circuit is composed of a compensation capacitor and a rectifier bridge, and is connected to the rear end of the magnetic field energy harvesting device through two AC output lines. The capacitance of the compensation capacitor is determined by the self-inductance and the power frequency of the magnetic field energy harvesting device.

[0061] The discharge protection circuit is composed of a voltage-stabilizing diode and a monitoring resistor, and the discharge protection circuit is connected to the rear end of the rectifier circuit through two DC output lines.

[0062] The TMR sensing circuit mainly detects changes in the surrounding magnetic field through the TMR chip. The TMR sensing circuit is placed in parallel and close to the single-core cable, and the direction of the magnetic field generated by the single-core cable is kept parallel to the sensitive axis direction of the TMR chip to obtain the maximum output voltage. At the same time, in order to maximize the current measurement impact caused by the energy acquisition device, the TMR chip is placed in close contact with the edge of the energy acquisition magnetic core and the AC output line, and the power frequency magnetic field direction of the AC line inside the rectifier circuit is perpendicular to the magnetic sensitive direction of the TMR sensor, reducing interference with the TMR sensing circuit.

[0063] The micro energy management circuit includes a filter capacitor, a two-stage DC-DC module, an energy storage capacitor and a status monitoring unit. The energy storage capacitor is connected in the middle of the two-stage DC-DC module. The second-stage DC-DC module outputs a regulated DC voltage. The status monitoring unit realizes the operation status monitoring of the magnetic field energy self-powered electromagnetic sensor by comparing the regulated DC voltage, the voltage across the energy storage capacitor, and the voltage across the monitoring resistor in the discharge circuit. The micro energy management circuit is connected to the rear end of the discharge circuit and to the front end of the TMR sensor circuit and the control circuit to supply power to the TMR power supply circuit and the control circuit. The rectifier circuit, the discharge circuit and the micro energy management circuit are integrated together and placed parallel to the TMR sensor circuit, so that the AC wiring in the rectifier circuit is perpendicular to the magnetic sensitivity direction of the TMR sensor, thereby reducing interference to the TMR sensor.

[0064] The operation status monitoring unit is composed of a sampling resistor, a voltage dividing resistor, a comparator, an indication pin and a protection element. By comparing the regulated DC voltage, the voltage across the energy storage capacitor, and the voltage across the monitoring resistor in the discharge circuit, the operation status monitoring of the magnetic field energy self-supply electromagnetic sensor is realized. The circuit diagram of the operation status monitoring unit is shown in the attached figure. Figure 4 shown.

[0065] The control circuit is composed of a central processing unit, a memory, an input / output interface, an analog-to-digital converter, etc., and the output indication pin of the operation status monitoring unit is connected to the control circuit.

[0066] The spatial layout and connection relationship between the various devices and circuits of the integrated magnetic field energy harvesting and magnetic sensing TMR sensor are shown in the attached figure. Figure 2shown. The energy-taking magnetic core is placed closely and parallelly above the single-core cable, and the two AC output lines connecting the coil are placed closely beside the magnetic core in parallel with the single-core cable; the rectifier circuit is connected to the rear end of the magnetic field energy-taking device, and the AC line inside the rectifier circuit is perpendicular to the single-core cable; the discharge protection circuit is connected to the rear end of the rectifier circuit through two DC output lines; the micro-energy management circuit is connected to the rear end of the discharge circuit, and connects the TMR sensor circuit and the front end of the control circuit to supply power to the TMR power supply circuit and the control circuit; the TMR sensor circuit is placed closely and parallelly above the single-core cable, so that the direction of the magnetic field generated by the single-core cable is parallel to the sensitive axis direction of the TMR chip, and the TMR chip is closely attached to the edges of the energy-taking magnetic core and the AC output line, and the power frequency magnetic field direction of the AC line inside the rectifier circuit is perpendicular to the magnetic sensitive direction of the TMR sensor, so as to reduce interference to the TMR sensor circuit; the rectifier circuit, the discharge circuit and the micro-energy management circuit are integrated together and placed parallel to the TMR sensor circuit; the control circuit is connected to the output indication pin of the operation status monitoring unit and placed parallel to the micro-energy management circuit.

[0067] The circuit model diagram of the magnetic field energy harvesting device, rectification circuit, discharge circuit and micro energy management circuit is shown in the attached figure. Figure 3 The single-core cable carries an AC current of I, and the number of bus turns is 1; the number of turns of the energy-taking coil is N, the self-inductance is L, the internal resistance is R, and the mutual inductance between the single-core cable and the energy-taking coil is M; the compensation capacitor is C0; the rectifier bridge is composed of four rectifier diodes D1, D2, D3, and D4; the voltage-stabilizing diode is D0, the monitoring resistor is R0, and the voltage across the monitoring resistor is U R ; The filter capacitor is C1, and the load size is R L , the voltage across the load is U O The energy storage capacitor is C, and the voltage across the energy storage capacitor is U C .

[0068] Embodiment 2 of the present invention provides an interference suppression method for a magnetic field energy-derived self-powered electromagnetic sensor, comprising the following steps:

[0069] Step 1: By adjusting the cable current, the magnetic field energy self-powered electromagnetic sensor is in an unsaturated state, a lightly saturated state, and a heavily saturated state, respectively, and the current excitation upper and lower limits of the sensor in the three working states and the output value of the TMR without energy extraction interference and the TMR output value with energy extraction interference are obtained;

[0070] The micro energy management circuit has three working states: an unsaturated state, i.e., the energy collected by the magnetic field energy harvesting device powers the load while charging the energy storage capacitor, but the energy storage capacitor is not yet fully charged; a lightly saturated state, i.e., the energy storage capacitor is fully charged and continuously powers the load, but the voltage of the discharge protection circuit does not exceed the discharge voltage value; and a heavily saturated state, i.e., the voltage of the discharge protection circuit exceeds the discharge voltage value and discharge is started.

[0071] The circuit diagram of the operating status monitoring unit is as attached. Figure 4 As shown. C is the voltage of the energy storage capacitor, U C-Ref is the set rated voltage of the energy storage capacitor, U O is the regulated output voltage of the micro energy management circuit and satisfies U C-Ref =k1U O , k1 is the reference coefficient; U R To monitor the resistor voltage, U R-Ref is the set discharge protection voltage and satisfies U R-Ref =k2U O , k2 is the reference coefficient.

[0072] Comparator 1 positive input voltage U 正1 The formula is as follows:

[0073] U 正1 =U C R2 / (R1+R2) (1)

[0074] Among them, U C is the voltage of the energy storage capacitor, R1 and R2 are the voltage dividing resistors at the positive input terminal of the operational comparator 1.

[0075] Comparator 1 negative input voltage U 负1 The formula is as follows:

[0076] U 负1 =U O R4 / (R3+R4) (2)

[0077] Among them, U O is the regulated output voltage of the micro energy management circuit, and R3 and R4 are voltage divider resistors at the negative input terminal of the operational comparator 1.

[0078] k1=R4(R1+R2) / R2(R3+R4) (3)

[0079] Wherein, k1 is a reference coefficient, R1 and R2 are voltage-dividing resistors at the positive input terminal of the operational comparator 1, and R3 and R4 are voltage-dividing resistors at the negative input terminal of the operational comparator 1.

[0080] Comparator 2 positive input voltage U 正2The formula is as follows:

[0081] U 正2 =U R R7 / (R6+R7) (4)

[0082] Among them, U R To monitor the resistor voltage, R6 and R7 are voltage divider resistors at the positive input of operational comparator 2.

[0083] Comparator 2 negative input voltage U 负2 The formula is as follows:

[0084] U 负2 =U O R9 / (R8+R9) (5)

[0085] Among them, U O is the regulated output voltage of the micro energy management circuit, and R8 and R9 are the voltage dividing resistors of the negative input terminal of the operational comparator 2.

[0086] k1=R9(R6+R7) / R7(R8+R9) (6)

[0087] Wherein, k2 is a reference coefficient, R6 and R7 are voltage-dividing resistors at the positive input terminal of the operational comparator 1, and R8 and R9 are voltage-dividing resistors at the negative input terminal of the operational comparator 1.

[0088] The two operational comparators compare the positive input voltage with the negative input voltage, and the operation status monitoring unit outputs two indication pins: (1) when the positive input voltage U 正1 <Negative input voltage U of operational comparator 1 负1 , calculate the positive input voltage U of comparator 2 正2 <Negative input voltage U of computational comparator 2 负2 , the indication pin 1 and the indication pin 2 both output a low level, and the micro energy management circuit is in an unsaturated state; (2) when the positive input voltage U 正1 ≥Negative input voltage U of operational comparator 1 负1 , calculate the positive input voltage U of comparator 2 正2 <Negative input voltage U of computational comparator 2 负2 , the output of the indication pin 1 is high level, the output of the indication pin 2 is low level, and the micro energy management circuit is in a light saturation state; (3) When the positive input voltage U 正1 ≥Negative input voltage U of operational comparator 1 负1 , calculate the positive input voltage U of comparator 2 正2 ≥Negative input voltage U of operational comparator 2 负2When the indication pin 1 and the indication pin 2 both output a high level, the micro energy management circuit is in a heavy saturation state.

[0089] When the current is small, the energy management circuit is in an unsaturated state. The energy collected by the energy acquisition device not only supplies power to the load but also charges the energy storage capacitor, but the energy storage capacitor is not yet fully charged. When the current continues to increase, the energy management circuit is in a lightly saturated state. The energy storage capacitor is fully charged and continues to supply power to the load, but the voltage of the discharge circuit does not exceed the discharge voltage value. When the current is too large, the energy management circuit is in a heavily saturated state. The voltage of the discharge protection circuit exceeds the discharge voltage value, and the discharge is started.

[0090] The positive input voltage is compared with the negative input voltage through two operational comparators. Furthermore, the operating status monitoring unit outputs two indication pins to determine the working status of the magnetic field energy self-powered electromagnetic sensor and the correction algorithm of the TMR output back-calculation function. Finally, the TMR output value is substituted into the correction algorithm to obtain the cable current value at this time.

[0091] The magnitude of the cable current is adjusted so that the magnetic field energy self-powered electromagnetic sensor operates in an unsaturated state, and the upper and lower limits of the current excitation when the sensor operates in the unsaturated state are obtained.

[0092] The magnitude of the cable current is adjusted so that the magnetic field energy self-powered electromagnetic sensor operates in a light saturation state, and the current excitation upper limit and lower limit when the sensor operates in the light saturation state are obtained.

[0093] The magnitude of the cable current is adjusted so that the magnetic field energy self-supply electromagnetic sensor operates in a heavy saturation state, and the current excitation upper limit and lower limit when the sensor operates in the heavy saturation state are obtained.

[0094] Step 2: According to the upper and lower limits of current excitation in the unsaturated state, lightly saturated state and heavily saturated state, the output values ​​of the TMR without energy extraction interference and the TMR output values ​​with energy extraction interference in each current range are evenly distributed to obtain experimental data. Combined with the cable current, the output functions of the TMR without energy extraction interference and the TMR output functions with energy extraction interference under the three working conditions are obtained;

[0095] The embodiment of the present invention adopts a magnetic core with a size of 5cm×5cm×8cm, and the energy taking device is as follows: Figure 5 Without the influence of magnetic core, energy taking coil and energized AC output line, that is, without interference, adjust the cable current within 0-1000A, record 20 sets of measurement values, and draw the function curve of cable current and TMR output as shown in the red curve below.

[0096] Taking the actual situation into consideration, the magnetic core, the energy taking coil and the energized AC outgoing line exist at the same time, that is, under the influence of the energy taking device, the cable current is adjusted to vary within 0-1000A.

[0097] According to the upper and lower limits of current excitation when the sensor works in an unsaturated state, 10 points are evenly distributed in the current range to obtain experimental data, and experimental data without energy extraction interference and with energy extraction interference in the unsaturated state are obtained. The working state relationship curve between the cable current in the unsaturated state and the TMR output with energy extraction interference and the working state relationship curve between the cable current in the unsaturated state and the TMR output without energy extraction interference are plotted, and the TMR output function without energy extraction interference in the unsaturated state and the TMR output function with energy extraction interference in the unsaturated state are obtained.

[0098] According to the upper and lower limits of current excitation when the sensor works in a light saturation state, 10 points are evenly distributed within the current range to obtain experimental data, and experimental data without energy extraction interference and with energy extraction interference in the light saturation state are obtained. The second working state relationship curve between the cable current in the light saturation state and the TMR output with energy extraction interference and the second working state relationship curve between the cable current in the light saturation state and the TMR output without energy extraction interference are plotted, and the TMR output function without energy extraction interference in the light saturation state and the TMR output function with energy extraction interference in the light saturation state are obtained.

[0099] According to the upper and lower limits of current excitation when the sensor works in the heavy saturation state, 10 points are evenly selected within the current range to obtain experimental data, and the experimental data without energy extraction interference and with energy extraction interference in the heavy saturation state are obtained. The three working state relationship curves of the cable current in the heavy saturation state and the TMR output with energy extraction interference and the three working state relationship curves of the cable current in the heavy saturation state and the TMR output without energy extraction interference are plotted, and the TMR output function without energy extraction interference in the heavy saturation state and the TMR output function with energy extraction interference in the heavy saturation state are obtained.

[0100] Step 3: Evenly distribute selected points in each current range to obtain experimental data, and obtain correction algorithms corresponding to different working states based on data fitting;

[0101] Based on the TMR output function in the unsaturated state without interference from energy extraction, a function fitting is performed on the TMR output function in the unsaturated state with interference from energy extraction, and the fitting result of the first-stage TMR output inverse function is obtained to obtain the correction algorithm A.

[0102] The TMR output function under the unsaturated state is disturbed by energy extraction, and the TMR output function under the lightly saturated state is disturbed by energy extraction. The fitting result of the second-stage TMR output inverse function is obtained, and the correction algorithm B is obtained.

[0103] Based on the TMR output function that is not disturbed by energy extraction in the heavily saturated state, a function fitting is performed on the TMR output function that is disturbed by energy extraction in the heavily saturated state, and the fitting result of the third-segment TMR output inverse function is obtained, thereby obtaining the correction algorithm C.

[0104] Working state one is an unsaturated state, working state two is a lightly saturated state, and working state three is a heavily saturated state.

[0105] The three-segment function curve of cable current and TMR output is drawn as follows Fig.10 As shown in the blue, yellow and green segmented curves. The blue curve is the cable current value in working state 1 under the influence of the energy extraction device; the yellow curve is the cable current value in working state 2 under the influence of the energy extraction device; the green curve is the cable current value in working state 3 under the influence of the energy extraction device. Comparing the TMR output curves under the ideal non-interference situation and the actual energy extraction device, it can be seen from the figure below that after considering the interference of the energy extraction device, the output of the TMR is no longer a completely linear function under the non-interference condition.

[0106] According to the three-segment function curves of cable current and TMR output under the influence of energy extraction device, the relationship between cable current and TMR output under three working conditions is fitted by Matlab tool, and the fitting result of TMR output segmented inverse function considering the influence of energy extraction device is obtained. The relationship between cable current and TMR output voltage is obtained, as shown in the attached figure. Figure 6 , Figure 7 and Figure 8 shown.

[0107] The TMR output segmented curve is fitted. When the working state is one, the accuracy is relatively high when the fitting function is a quintic polynomial. Therefore, the first segment of the TMR output reverse fitting function considering the influence of the energy extraction device can be obtained, that is, the correction algorithm A is:

[0108] I1=-17050U 5 +27880U 4 -15930U 3 +3826U 2 +394.1U+12.3 (5)

[0109] In working state 2, when the fitting function is a quartic polynomial, the accuracy is relatively high. Therefore, the second-stage inverse fitting function of the TMR output considering the influence of the energy extraction device can be obtained, that is, the correction algorithm B is:

[0110] I2=6573U 4 -22410U 3 +28230U 2 -14740U+3156 (6)

[0111] In working state three, when the fitting function is a seventh-order polynomial, the accuracy is relatively high. Therefore, the third-stage inverse fitting function of the TMR output considering the influence of the energy extraction device can be obtained, that is, the correction algorithm C is:

[0112]

[0113] Among them, I1, I2, and I3 represent the cable current values ​​under different working conditions, and U represents the output value of TMR.

[0114] Step 4: Determine the working state according to the indication pin output by the operation state monitoring unit, fit the TMR output function disturbed by energy extraction in three working states in sections according to the corresponding correction algorithm, obtain the corrected cable current values ​​in the three working states according to the TMR output voltage value, combine the corrected cable current values ​​in the three working states, and obtain the cable current value after interference suppression, so as to solve the problem of interference of magnetic field energy extraction on the magnetic field around TMR.

[0115] Software is written in the controller to implement segmented correction. Further, the segmented correction includes judging the status of the two indicating pins output by the running status monitoring unit. The algorithm flow chart of segmented fitting of the TMR output back-calculation function is shown in the attached figure. Fig. 9 As shown:

[0116] When the positive input voltage U 正1 <Negative input voltage U of operational comparator 1 负1 When the indication pin 1 and the indication pin 2 both output a low level, the TMR output inverse function is fitted according to the correction algorithm A, and the cable current value at this time can be obtained by substituting the TMR output value into the correction algorithm A;

[0117] When the positive input voltage U 正1 ≥Negative input voltage U of operational comparator 1 负1 , the positive input voltage U of the operational comparator 2 of the operating status monitoring unit 正2 <Negative input voltage U of computational comparator 2 负2 When the indicator pin 1 outputs a high level and the indicator pin 2 outputs a low level, the TMR output inverse function is fitted according to the correction algorithm B, and the cable current value at this time can be obtained by substituting the TMR output value into the correction algorithm B;

[0118] When the positive input voltage U 正2 ≥Negative input voltage U of operational comparator 2 负2When the indication pin 1 and the indication pin 2 both output a high level, the TMR output inverse function is fitted according to the correction algorithm C, and the cable current value at this time can be obtained by substituting the TMR output value into the correction algorithm C. Therefore, the segmented correction method based on data fitting proposed in the present invention, taking into account the influence of the energy extraction device, can not only realize the self-power supply of TMR, but also solve the problem of interference of magnetic field energy extraction on the magnetic field around TMR, effectively improve the accuracy of TMR output in the magnetic field energy extraction self-powered electromagnetic sensor, and thus improve the accuracy of cable current monitoring.

[0119] The beneficial effect of the present invention is that the present invention proposes a magnetic field energy-taking self-powered electromagnetic sensor and its interference suppression method, specifically designs a magnetic field energy-taking self-powered TMR sensor, and establishes the spatial layout and connection relationship between each part of the device and the circuit, so as to reduce the interference of magnetic field energy taking on magnetic sensing; at the same time, the three working states of the TMR sensor are considered, and a three-segment correction algorithm is obtained based on data fitting, and the TMR output inverse function is segmentedly corrected and fitted by judging the working state of the indicator pin output by the operation status monitoring unit, and the accurate cable current value is obtained according to the TMR output voltage value, so as to further improve the sensing accuracy. This magnetic field energy-taking self-powered electromagnetic sensor and its interference suppression method can not only realize the self-powering of the TMR sensor based on magnetic field energy taking, but also effectively solve the problem of insufficient sensing accuracy caused by the nonlinear interference of the magnetic field energy taking device on the magnetic sensing due to different working states, improve the accuracy of TMR output in the magnetic field energy-taking self-powered electromagnetic sensor, and thus improve the accuracy of cable current monitoring.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetic field energy-taking self-powered electromagnetic sensor, comprising a magnetic field energy-taking device, a rectifier circuit, a discharge protection circuit, a micro-energy management circuit, a TMR sensor circuit and a control circuit; characterized in that: The magnetic field energy harvesting device comprises an H-shaped magnetic core and an energy harvesting coil, wherein the energy harvesting coil is wound on the H-shaped magnetic core, and the magnetic core wound with the energy harvesting coil is placed close to the single-core cable; two AC output lines connecting the coil are placed parallel to the single-core cable and close to the magnetic core; The rectifier circuit is connected to the rear end of the magnetic field energy harvesting device, and the AC wiring inside the rectifier circuit is perpendicular to the single-core cable; The discharge protection circuit is connected to the rear end of the rectifier circuit through two DC output lines; The TMR sensing circuit includes a TMR chip. The TMR sensing circuit is placed in parallel and close to the top of the single-core cable, and the direction of the magnetic field generated by the single-core cable is kept parallel to the sensitive axis direction of the TMR chip. The TMR chip is placed close to the edge of the energy-taking magnetic core and the AC output line. The micro energy management circuit includes a state monitoring unit, the micro energy management circuit is connected to the rear end of the discharge circuit, and is connected to the front end of the TMR sensor circuit and the control circuit. The rectifier circuit, the discharge circuit and the micro energy management circuit are integrated together and placed parallel to the TMR sensor circuit, and the AC wiring in the rectifier circuit is perpendicular to the magnetic sensitivity direction of the TMR sensor circuit. The control circuit is connected to the state monitoring unit in the micro energy management circuit and is placed in parallel with the micro energy management circuit.

2. A method for suppressing interference of a magnetic field self-powered electromagnetic sensor, used for operating a magnetic field self-powered electromagnetic sensor according to claim 1, characterized in that: The following steps are involved: Step 1: By adjusting the cable current, the magnetic field energy self-powered electromagnetic sensor is in an unsaturated state, a lightly saturated state, and a heavily saturated state, respectively, and the current excitation upper and lower limits of the sensor in the three working states and the output value of the TMR without energy extraction interference and the TMR output value with energy extraction interference are obtained; Step 2: According to the upper and lower limits of current excitation in the unsaturated state, lightly saturated state and heavily saturated state, the output values ​​of the TMR without energy extraction interference and the TMR output values ​​with energy extraction interference in each current range are evenly distributed to obtain experimental data. Combined with the cable current, the output functions of the TMR without energy extraction interference and the TMR output functions with energy extraction interference under the three working conditions are obtained; Step 3: Based on the output functions of the TMR without energy extraction interference in the unsaturated state, the lightly saturated state and the heavily saturated state, the output functions of the TMR with energy extraction interference in the unsaturated state, the lightly saturated state and the heavily saturated state are fitted respectively to obtain the correction algorithms corresponding to the three working states; Step 4: Determine the working state according to the operation state monitoring unit, and fit the TMR output function affected by energy extraction interference in the unsaturated state, lightly saturated state, and heavily saturated state in sections according to the corresponding correction algorithm. Combine the corrected cable current values ​​under the three working states to obtain the cable current value after interference suppression.

3. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: include: In step 1, the energy collected by the magnetic field energy harvesting device is used to supply power to the load and to charge the energy storage capacitor at the same time, but when the energy storage capacitor is not fully charged, it is in an unsaturated state; The energy storage capacitor is fully charged and continuously supplies power to the load, but the voltage of the discharge protection circuit does not exceed the discharge voltage value, which is a light saturation state; When the voltage of the discharge protection circuit exceeds the discharge voltage value and the discharge is started, it is in a heavy saturation state.

4. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 3, characterized in that: By adjusting the cable current so that the magnetic field energy self-powered electromagnetic sensor works in an unsaturated state, the upper and lower limits of the current excitation when the sensor works in the unsaturated state are obtained; Adjust the cable current so that the magnetic field energy self-powered electromagnetic sensor works in a light saturation state, and obtain the current excitation upper limit and lower limit of the sensor working in the light saturation state; The cable current is adjusted so that the magnetic field energy self-powered electromagnetic sensor operates in a heavy saturation state, and the current excitation upper limit and lower limit when the sensor operates in the heavy saturation state are obtained.

5. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: In step 2, according to the upper and lower limits of current excitation when the sensor operates in an unsaturated state, experimental data with and without energy extraction interference in the unsaturated state are obtained within the current range, and a relationship curve between the cable current in the unsaturated state and the TMR output with energy extraction interference and a relationship curve between the cable current in the unsaturated state and the TMR output without energy extraction interference are plotted to obtain a TMR output function without energy extraction interference in the unsaturated state and a TMR output function with energy extraction interference in the unsaturated state.

6. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: In step 2, according to the upper and lower limits of current excitation when the sensor operates in a light saturation state, experimental data with and without energy extraction interference in the light saturation state are obtained within the current range, and a relationship curve between the cable current in the light saturation state and the TMR output with energy extraction interference and a relationship curve between the cable current in the light saturation state and the TMR output without energy extraction interference are plotted to obtain a TMR output function without energy extraction interference in the light saturation state and a TMR output function with energy extraction interference in the light saturation state.

7. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: In step 2, according to the upper and lower limits of the current excitation when the sensor works in the heavy saturation state, experimental data without energy extraction interference and with energy extraction interference in the heavy saturation state are obtained within the current range, and the relationship curve between the cable current in the heavy saturation state and the TMR output with energy extraction interference and the relationship curve between the cable current in the heavy saturation state and the TMR output without energy extraction interference are plotted to obtain the TMR output function without energy extraction interference in the heavy saturation state and the TMR output function with energy extraction interference in the heavy saturation state.

8. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: The present invention comprises: In step 3, based on the TMR output function that is not disturbed by energy extraction in an unsaturated state, a function fitting is performed on the TMR output function that is disturbed by energy extraction in an unsaturated state to obtain a correction algorithm A; Based on the TMR output function in the light saturation state without interference from energy extraction, the TMR output function in the light saturation state with interference from energy extraction is fitted to obtain a correction algorithm B; Based on the TMR output function in the heavily saturated state without interference from energy extraction, a function fitting is performed on the TMR output function in the heavily saturated state with interference from energy extraction to obtain a correction algorithm C.

9. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 2, characterized in that: The present invention comprises: In step 4, the two operational comparators of the operation status monitoring unit compare the positive input voltage with the negative input voltage to monitor three working states, specifically including: When the positive input voltage of the operational comparator 1 is less than the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the micro energy management circuit is in an unsaturated state; When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the micro energy management circuit is in a light saturation state; When the positive input voltage of the operational comparator 1 is ≥ the negative input voltage, and the positive input voltage of the operational comparator 2 is ≥ the negative input voltage, the micro energy management circuit is in a heavy saturation state.

10. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 9, characterized in that: include: By judging the positive input voltage and negative input voltage of the two operational comparators of the operation status monitoring unit, the circuit status under three working states is monitored. The specific process includes: When the positive input voltage of the operational comparator 1 is less than the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the energy harvesting device collects energy from the magnetic field to power the load and charge the energy storage capacitor; When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is less than the negative input voltage, the energy storage capacitor stops charging, and the collected energy continues to supply power to the load; When the positive input voltage of the operational comparator 1 is greater than or equal to the negative input voltage, and the positive input voltage of the operational comparator 2 is greater than or equal to the negative input voltage, the voltage stabilizing diode D0 breaks down in reverse, and the discharge protection circuit starts to discharge.

11. The interference suppression method of a magnetic field energy self-powered electromagnetic sensor according to claim 9, characterized in that: The process of segmented fitting of the TMR output inverse function according to the corresponding correction algorithm includes: When the positive input voltage U 正1 <Negative input voltage U of operational comparator 1 负1 When , the TMR output inverse function is fitted according to the correction algorithm A, and the TMR output value is substituted into the correction algorithm A to obtain the corrected cable current value in the current working state; When the positive input voltage U 正1 ≥Negative input voltage U of operational comparator 1 负1 , the positive input voltage U of the operational comparator 2 正2 <Negative input voltage U of computational comparator 2 负2 When , the TMR output inverse function is fitted according to the correction algorithm B, and the TMR output value is substituted into the correction algorithm B to obtain the corrected cable current value in the current working state; When the positive input voltage U 正2 ≥Negative input voltage U of operational comparator 2 负2 When the TMR output inverse function is fitted according to the correction algorithm C, the TMR output value is substituted into the correction algorithm C to obtain the corrected cable current value in the current working state.

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