A residual current detection device based on TMR tunnel magnetoresistance

Abstract

A residual current detection device based on TMR tunnel magnetoresistance includes a residual current detection sensor and a signal processing circuit. The residual current detection sensor is sleeved on the main circuit power line. The output end of the residual current detection sensor is connected to the input end of the signal processing circuit. The residual current detection sensor includes a TMR tunnel magnetoresistance sensor. The signal processing circuit includes an operational amplifier circuit, a signal conditioning circuit, a temperature signal acquisition circuit, a signal processing control circuit and a tripping execution circuit connected in sequence. The operational amplifier circuit is connected to the TMR tunnel magnetoresistance sensor to amplify the signal output by the TMR tunnel magnetoresistance sensor. The signal conditioning circuit is used to filter and zero the signal output by the operational amplifier circuit. The temperature signal acquisition circuit is used to detect changes in ambient temperature. The signal processing control circuit is connected to the signal conditioning circuit and the temperature signal acquisition circuit. The present invention has a temperature compensation function and is less affected by temperature.

Description

Technical Field

[0001] The invention relates to a low-voltage circuit breaker, and in particular to a residual current detection device based on TMR tunnel magnetoresistance. Background Art

[0002] Low-voltage circuit breakers are important control components of power systems. Most of the residual current operated circuit breakers on the market now use zero-sequence current transformers to detect the current vector sum of the main circuit to detect whether there is leakage in the main circuit. However, this zero-sequence current transformer has the disadvantages of low detection accuracy and being easily affected by ambient temperature and can only be used to detect low-frequency AC or pulsating DC residual current. In addition, the zero-sequence current transformer core has the problem of magnetic saturation and the defect of a narrow residual current detection range. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a residual current detection device based on TMR tunnel magnetoresistance with high accuracy and high reliability.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A residual current detection device based on TMR tunnel magnetoresistance, comprising a residual current detection sensor, a signal processing circuit and a power supply circuit for supplying power to the residual current detection sensor and the signal processing circuit, wherein the output end of the residual current detection sensor is connected to the input end of the signal processing circuit, the residual current detection sensor comprises a TMR tunnel magnetoresistance sensor, and the signal processing circuit comprises an operational amplifier circuit, a signal conditioning circuit, a temperature signal acquisition circuit, a signal processing control circuit and a tripping execution circuit which are connected in sequence;

[0006] The input end of the operational amplifier circuit is connected to the output end of the TMR tunnel magnetoresistive sensor and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor. The signal conditioning circuit is used to filter and zero the signal output by the operational amplifier circuit. The temperature signal acquisition circuit is used to detect the ambient temperature. The input end of the signal processing control circuit is respectively connected to the output ends of the signal conditioning circuit and the temperature signal acquisition circuit. The signal processing control circuit performs compensation processing on the received signal in combination with a preset temperature change compensation model. After the residual current exceeds a threshold preset by the signal processing control circuit, the signal processing control circuit outputs a trigger signal to the tripping execution circuit to activate the tripping execution circuit.

[0007] Furthermore, the operational amplifier circuit includes a differential operational amplifier circuit and an inverse amplifier circuit. The input end of the differential operational amplifier circuit is connected to the output end of the TMR tunnel magnetoresistive sensor and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor. The inverse amplifier circuit is connected to the differential operational amplifier circuit and performs an optional gain amplification process on the output signal of the differential operational amplifier circuit.

[0008] Furthermore, an analog conversion switch is connected between the operational amplifier circuit and the signal processing control circuit. Under the control of the signal processing control circuit, the analog conversion switch can selectively adjust the gain of the reverse amplifier circuit.

[0009] Furthermore, the operational amplifier circuit includes an operational amplifier, and a reference voltage of the operational amplifier circuit is half of a power supply voltage of the operational amplifier.

[0010] Furthermore, the residual current detection sensor also includes a shielding device, a circuit board and a magnetic focusing ring. The TMR tunnel magnetoresistance sensor is supported on the surface of the circuit board, and the TMR tunnel magnetoresistance sensor is arranged perpendicular to the magnetic field direction in the magnetic focusing ring; the shielding device is arranged around the magnetic focusing ring to shield the influence of external interference on the TMR tunnel magnetoresistance sensor.

[0011] Furthermore, it also includes an analog test circuit for reliability testing, wherein the analog test winding of the analog test circuit is wound on a magnetic focusing ring, the analog test circuit is connected to a signal processing control circuit and is controlled by the signal processing control circuit to generate an analog residual current signal for reliability testing.

[0012] Furthermore, the residual current detection sensor is an annular structure, the circuit board is annular, the annular magnetic focusing ring is stacked parallel to the circuit board, a magnetic focusing ring notch is provided on the radial outer wall of the magnetic focusing ring, and the magnetic focusing ring notch passes through the side of the magnetic focusing ring facing the circuit board, a connecting plate protruding vertically from the circuit board is provided on the circuit board, a TMR tunnel magnetoresistance sensor is provided on the side of the connecting plate, and the TMR tunnel magnetoresistance sensor and the connecting plate extend into the magnetic focusing ring notch.

[0013] Furthermore, the signal conditioning circuit includes at least one filtering circuit and a zeroing circuit. The filtering circuit is an active filtering circuit, which is used to filter out high-frequency interference generated by the external environment to the TMR magnetoresistive sensor. The output end of the zeroing circuit is connected to the signal processing control circuit, which is used to adjust the signal after filtering by the active filtering circuit and output a reference voltage when there is no residual current input.

[0014] Further, the active filter circuit includes an operational amplifier U2A, a capacitor C2, a capacitor C3, a resistor R12 and a resistor R13, the positive input terminal of the operational amplifier U2A is connected to one end of the capacitor C3 and one end of the resistor R13, the reverse input terminal of the operational amplifier U2A is connected to one end of the capacitor C2, the reverse input terminal of the operational amplifier U2A is connected to the output terminal of the operational amplifier U2A, the output terminal of the operational amplifier U2A is connected to the input terminal of the zero adjustment circuit, the other end of the capacitor C2 and the other end of the resistor R13 are connected to one end of the resistor R12, the other end of the resistor R12 is connected to the output terminal of the operational amplifier circuit, and the other end of the capacitor C3 is connected to GND.

[0015] Further, the differential operational amplifier circuit comprises a resistor R5, a resistor R6, a resistor R9, a resistor R10 and an operational amplifier U1A, the positive input end of the operational amplifier U1A is connected to one end of the resistor R10 and the resistor R9, the reverse input end of the operational amplifier U1A is connected to one end of the resistor R6 and the resistor R5, the other end of the resistor R5 is connected to the output end of the operational amplifier U1A, the other end of the resistor R6 is connected to the residual current detection sensor as the positive pole of the operational amplifier circuit input end, the other end of the resistor R9 is connected to the residual current detection sensor as the negative pole of the operational amplifier circuit input end, and the other end of the resistor R10 is connected to the power supply circuit (101);

[0016] The reverse amplifier circuit includes a resistor RN, a resistor R7, a resistor R8, a resistor R11, a capacitor C1 and an operational amplifier U1B, wherein the positive input terminal of the operational amplifier U1B is connected to one end of the resistor R11, the reverse input terminal of the operational amplifier U1B is connected to one end of the resistor R7 and one end of the resistor RN, the output terminal of the operational amplifier U1B is connected to one end of the resistor R8 and the other end of the resistor RN, the other end of the resistor R7 is connected to the output terminal of the operational amplifier U1A, the other end of the resistor R11 is connected to the power supply circuit, the other end of the resistor R8 is connected to one end of the capacitor C1 and the signal conditioning circuit, and the other end of the capacitor C1 is connected to GND.

[0017] Further, the differential operational amplifier circuit includes a resistor R5, a resistor R6, a resistor R9, a resistor R10 and an operational amplifier U1A, the positive input end of the operational amplifier U1A is connected to one end of the resistor R10 and the resistor R9, the reverse input end of the operational amplifier U1A is connected to one end of the resistor R6 and the resistor R5, the other end of the resistor R5 is connected to the output end of the operational amplifier U1A, the other end of the resistor R6 is connected to the residual current detection sensor as the positive pole of the operational amplifier circuit input end, the other end of the resistor R9 is connected to the residual current detection sensor as the negative pole of the operational amplifier circuit input end, and the other end of the resistor R10 is connected to the power supply circuit;

[0018] The reverse amplification circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R7, a resistor R8, a resistor R11, a capacitor C1, an operational amplifier U1B and an analog conversion switch S1, wherein the common end of the analog conversion switch S1 is connected to the reverse input end of the operational amplifier U1B, the other end of the analog conversion switch S1 can be selectively connected to any one end of the resistor R1, the resistor R2, the resistor R3 and the resistor R4, and the other ends of the resistors R1, R2, R3 and R4 are all connected to the output end of the operational amplifier U1B;

[0019] The positive input terminal of the operational amplifier U1B is connected to one end of the resistor R11, the reverse input terminal of the operational amplifier U1B is connected to one end of the resistor R7, the output terminal of the operational amplifier U1B is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the output terminal of the operational amplifier U1A, the other end of the resistor R11 is connected to the power supply circuit, the other end of the resistor R8 is connected to one end of the capacitor C1 and the signal conditioning circuit, and the other end of the capacitor C1 is connected to GND.

[0020] The present invention discloses a residual current detection device based on TMR tunnel magnetoresistance. When a residual current signal is generated, the TMR tunnel magnetoresistance sensor arranged in the residual current detection sensor can output a differential voltage signal consistent with the residual current waveform. When the signal processing circuit amplifies the differential voltage signal, the received signal is compensated according to the ambient temperature change collected by the temperature signal acquisition circuit and combined with a preset temperature change compensation model. The signal processing control circuit performs AD conversion on the received signal and transmits it to the tripping execution circuit. After temperature compensation, the device has the characteristics of good linearity, little influence by temperature, almost no attenuation at high frequency, wide detection range, etc., and avoids the interference of temperature change on the detection accuracy. Moreover, the residual current detection device of the present invention can detect residual current types such as AC, pulsating DC, smooth DC, and composite current below 10KHz.

[0021] In addition, a magnetic focusing ring and a shielding device are provided in the residual current detection device. The magnetic focusing ring has the characteristic of high magnetic permeability. When the magnetic field changes, the magnetic field generated by the residual current mainly forms a closed loop through the magnetic focusing ring, and a shielding device is provided around the magnetic focusing ring to avoid the influence of external disturbances on the TMR tunnel magnetoresistive sensor, thereby improving the detection accuracy.

[0022] In addition, by setting an analog conversion switch S1, the signal processing control circuit controls the gain adjustment of the reverse amplifier circuit through the analog conversion switch S1, so that the amplification factor of the operational amplifier circuit can be adjusted; an analog test circuit for detecting the reliability of the device is also set, and the analog test circuit generates an analog residual current signal for detecting the action characteristics of the device to ensure that product failures can be discovered in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a residual current detection device based on TMR tunnel magnetoresistance of the present invention;

[0024] Figure 2 It is a circuit diagram of an operational amplifier circuit in a residual current detection device based on TMR tunnel magnetoresistance of the present invention;

[0025] Figure 3 It is a circuit diagram of an active filter circuit in a residual current detection device based on TMR tunnel magnetoresistance of the present invention;

[0026] Figure 4 The present invention is a structural diagram of a residual current detection sensor based on TMR tunnel magnetoresistance. DETAILED DESCRIPTION

[0027] The following is combined with Figures 1 to 4 The given examples further illustrate the specific implementation of a residual current detection device based on TMR tunnel magnetoresistance of the present invention. The residual current detection device based on TMR tunnel magnetoresistance of the present invention is not limited to the description of the following examples.

[0028] A residual current detection device based on TMR tunnel magnetoresistance, which can be used for residual circuit protection of a circuit breaker, comprises a residual current detection sensor 112, a signal processing circuit 113 and a power supply circuit 101 for supplying power to the residual current detection sensor 112 and the signal processing circuit 113, wherein the main circuit power line passes through the residual current detection sensor 112, the output end of the residual current detection sensor 112 is connected to the input end of the signal processing circuit 113, the residual current detection sensor 112 comprises a TMR tunnel magnetoresistance sensor 108, and the signal processing circuit 113 comprises an operational amplifier circuit 102, a signal conditioning circuit 103, a temperature signal acquisition circuit 105, a signal processing control circuit 104 and a tripping execution circuit 107 which are connected in sequence;

[0029] The input end of the operational amplifier circuit 102 is connected to the output end of the TMR tunnel magnetoresistive sensor 108, and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor 108. The signal conditioning circuit 103 is used to filter and zero the signal output by the operational amplifier circuit 102. The temperature signal acquisition circuit 105 is used to detect the ambient temperature. The input end of the signal processing control circuit 104 is respectively connected to the output ends of the signal conditioning circuit 103 and the temperature signal acquisition circuit 105. The signal processing control circuit 104 performs compensation processing on the received signal in combination with a preset temperature change compensation model. The temperature change compensation model is obtained during the test process. The signal processing control circuit 104 pre-compensates the sampling signal offset caused by temperature problems based on the temperature change test data. After the residual current exceeds the threshold preset by the signal processing control circuit 104, the signal processing control circuit 104 outputs a trigger signal to the tripping execution circuit 107 to activate the tripping execution circuit 107, and the circuit breaker trips and cuts off the power.

[0030] The residual current detection device based on TMR tunnel magnetoresistance of the present invention, when generating a residual current signal, the TMR tunnel magnetoresistance sensor 108 arranged in the residual current detection sensor 112 can output a differential voltage signal consistent with the residual current waveform, and when the signal processing circuit 113 amplifies the differential voltage signal, it compensates the received signal according to the ambient temperature change collected by the temperature signal acquisition circuit 105 and the preset temperature change compensation model, and the signal processing control circuit 104 performs AD conversion on the received signal and transmits it to the tripping execution circuit 107. After temperature compensation, it has the characteristics of good linearity, little influence by temperature, almost no attenuation of high frequency, wide detection range, etc., and avoids the interference of temperature change on detection accuracy. In addition, the residual current detection device of the present invention can detect residual current types such as AC, pulsating DC, smooth DC, composite current, etc. below 10KHz.

[0031] Combination Figure 1-4 An embodiment of a residual current detection device based on TMR tunnel magnetoresistance is introduced in detail. The residual current detection device based on TMR tunnel magnetoresistance includes a residual current detection sensor 112, a signal processing circuit 113 and a power supply circuit 101. The power supply circuit 101 performs voltage reduction processing on the power supply voltage by a linear voltage reduction method or a switching power supply voltage reduction method, and then supplies power to the residual current detection sensor 112 and the signal processing circuit 113 respectively.

[0032] The residual current detection sensor 112 is a ring structure. Figure 4The residual current detection sensor is mounted on the main circuit power line, and the output end 115 of the residual current detection sensor 112 is connected to the input end of the signal processing circuit 113. The preferred residual current detection sensor 112 includes a shielding device 110, a magnetic ring 109 and a TMR tunnel magnetoresistive sensor 108. The TMR tunnel magnetoresistive sensor 108 is connected to the surface of the circuit board 114 and its cross section (that is, the side of the patch component) is perpendicular to the magnetic field direction in the magnetic ring 109. The circuit board 114 is used to arrange the input and output lines of the TMR tunnel magnetoresistive sensor 108, and the output end 115 is connected to the input end of the signal processing circuit 113. The magnetic ring 109 is made of a soft magnetic material with high magnetic permeability. When the magnetic field changes, because the magnetic conductivity of the magnetic ring 109 is much higher than the air gap in the space, the magnetic field generated by the residual current mainly forms a closed loop through the magnetic ring 109. The shielding device 110 is composed of a bottom 1101 and a cover 1102 and is supported around the magnetic focusing ring 109. Insulating material is filled between the shielding device 110 and the magnetic focusing ring 109 to shield the influence of external disturbances on the TMR tunnel magnetoresistive sensor 108. The TMR tunnel magnetoresistive sensor 108 is a magnetic sensitive element. When a residual current signal is generated, the TMR tunnel magnetoresistive sensor 108 outputs a differential voltage signal consistent with the residual current waveform. The TMR tunnel magnetoresistive sensor 108 detects residual currents such as AC below 10KHz, pulsating DC, smooth DC, and composite current. Compared with ordinary zero-sequence current transformers designed with soft magnetic materials, ordinary zero-sequence current transformers have a magnetic saturation problem. When the detection current exceeds a certain value, its output is nonlinear or the output is basically unchanged. The TMR tunnel magnetoresistive sensor 108 does not have this problem and thus has a wider detection range.

[0033] In addition, the existing TMR tunnel magnetoresistive sensor 108 is mostly used to detect the A-level main circuit current, but not for mA-level residual current detection, and the TMR used to detect the residual current requires a magnetic ring 109, and the TMR tunnel magnetoresistive sensor 108 is placed at a perpendicular position to the radial section of the magnetic ring 109, while the detection of the main circuit current does not require such placement. At present, the residual current detection sensor 112 uses an open-loop method for detection, and can also use a closed-loop method for detection by adding a feedback winding. Specifically, the circuit board 114 is annular, and the annular magnetic focusing ring 109 is stacked parallel to the circuit board 114. A magnetic focusing ring notch is provided on the radial outer wall of the magnetic focusing ring 109, and the magnetic focusing ring notch penetrates the side surface of the magnetic focusing ring 109 facing the circuit board 114. A connecting plate is provided on the circuit board 114 which protrudes vertically from the circuit board 114, and a TMR tunnel magnetoresistive sensor 108 is provided on the side of the connecting plate. The TMR tunnel magnetoresistive sensor 108 and the connecting plate extend into the magnetic focusing ring notch, so that the TMR tunnel magnetoresistive sensor 108 is placed on the radial cross section of the magnetic focusing ring 109.

[0034] The signal processing circuit 113 receives the differential voltage signal output by the TMR tunnel magnetoresistive sensor 108, and controls the action of the actuator of the circuit breaker after amplification and filtering by the signal processing circuit 113. The signal processing circuit 113 includes an operational amplifier circuit 102, a signal conditioning circuit 103, a temperature signal acquisition circuit 105, a signal processing control circuit 104 and a tripping execution circuit 107 connected in sequence. The input end of the operational amplifier circuit 102 is connected to the output end of the TMR tunnel magnetoresistive sensor 108, and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor 108. The signal conditioning circuit 103 is used to filter and zero the signal output by the operational amplifier circuit 102. The temperature signal acquisition circuit 105 is used to detect changes in ambient temperature. The input end of the signal processing control circuit 104 is connected to the output end of the signal conditioning circuit 103 and the temperature signal acquisition circuit 105 respectively. The signal processing control circuit 104 performs compensation processing on the received signal in combination with a preset temperature change compensation model, and performs AD conversion on the received signal and transmits it to the tripping execution circuit 107. After the residual current exceeds the threshold value preset by the signal processing control circuit 104, the signal processing control circuit 104 outputs a trigger signal to the tripping execution circuit 107 to activate the tripping execution circuit 107, and the circuit breaker trips and cuts off the power. It should be noted that the signal processing control circuit 104 includes a single-chip microcomputer, on which a temperature change compensation model is set, and the threshold comparison is also implemented by the single-chip microcomputer. A method of a temperature change compensation model is to obtain a fitting curve by fitting based on multiple sets of historical temperature compensation data, and the current temperature collected by the temperature signal acquisition circuit 105 and the signal collected by the signal conditioning circuit 103 are brought into the fitting curve to obtain a compensated signal.

[0035] The operational amplifier circuit 102 includes an operational amplifier, and preferably, the reference voltage of the operational amplifier circuit 102 is half of the power supply voltage of the operational amplifier. The operational amplifier circuit 102 includes a differential operational amplifier circuit and an inverting amplifier circuit, wherein the input end of the differential operational amplifier circuit is connected to the output end of the TMR tunnel magnetoresistive sensor 108 for amplifying the signal output by the TMR tunnel magnetoresistive sensor 108, and the input end of the inverting amplifier circuit is connected to the output end of the differential operational amplifier circuit, and the inverting amplifier circuit is used to amplify the output signal of the differential operational amplifier circuit with a selectable gain, and the amplified signal V1 is transmitted to the signal conditioning circuit 103. Specifically, the selectable gain processing of the inverting amplifier circuit is realized by an analog conversion switch S1, and the analog conversion switch S1 is connected between the operational amplifier circuit 102 and the signal processing control circuit 104, and the analog conversion switch S1 is controlled by the signal processing control circuit 104. Of course, the operational amplifier circuit 102 and the analog conversion switch S1 circuit can be replaced by a programmable operational amplifier PGA.

[0036] Combination Figure 2 A connection method is provided in which an operational amplifier circuit 102 and an analog conversion switch S1 are provided; the differential operational amplifier circuit includes a resistor R5, a resistor R6, a resistor R9, a resistor R10 and an operational amplifier U1A, the positive input end of the operational amplifier U1A is connected to one end of the resistor R10 and the resistor R9, the reverse input end of the operational amplifier U1A is connected to one end of the resistor R6 and the resistor R5, the other end of the resistor R5 is connected to the output end of the operational amplifier U1A, the other end of the resistor R6 is connected to the residual current detection sensor 112 as the positive pole of the input end of the operational amplifier circuit 102, the other end of the resistor R9 is connected to the residual current detection sensor 112 as the negative pole of the input end of the operational amplifier circuit 102, and the other end of the resistor R10 is connected to the power supply circuit 101; wherein, the resistor R5=resistor R10, the resistor R6=resistor R9, and the circuit gain is R5 / R6.

[0037] The reverse amplification circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R7, a resistor R8, a resistor R11, a capacitor C1, an operational amplifier U1B and an analog conversion switch S1, wherein the common end of the analog conversion switch S1 is connected to the reverse input end of the operational amplifier U1B, the other end of the analog conversion switch S1 can be selectively connected to any one end of the resistor R1, the resistor R2, the resistor R3 and the resistor R4, and the other ends of the resistors R1, R2, R3 and R4 are all connected to the output end of the operational amplifier U1B;

[0038] The positive input terminal of the operational amplifier U1B is connected to one end of the resistor R11, the reverse input terminal of the operational amplifier U1B is connected to one end of the resistor R7, the output terminal of the operational amplifier U1B is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the output terminal of the operational amplifier U1A, the other end of the resistor R11 is connected to the power supply circuit 101, the other end of the resistor R8 is connected to one end of the capacitor C1 and the signal conditioning circuit 103, the other end of the capacitor C1 is connected to GND, and the signal outputted by the other end of the resistor R8 to the signal conditioning circuit 103 is V1.

[0039] Of course, if the analog conversion switch S1 is not needed to perform optional gain adjustment on the reverse amplifier circuit, the analog conversion switch S1 can be omitted. In this case, the reverse amplifier circuit includes a resistor RN, a resistor R7, a resistor R8, a resistor R11, a capacitor C1 and an operational amplifier U1B, wherein the positive input end of the operational amplifier U1B is connected to one end of the resistor R11, the reverse input end of the operational amplifier U1B is connected to one end of the resistor R7 and one end of the resistor RN, the output end of the operational amplifier U1B is connected to one end of the resistor R8 and the other end of the resistor RN, the other end of the resistor R7 is connected to the output end of the operational amplifier U1A, the other end of the resistor R11 is connected to the power supply circuit 101, the other end of the resistor R8 is connected to one end of the capacitor C1 and the signal conditioning circuit 103, and the other end of the capacitor C1 is connected to GND. The adjustment resistor is any one of the resistors R1, R2, R3 and R4, and the other end of the resistor R8 outputs the amplified signal V1. It should be noted that when the resistor RN is a fixed resistance resistor, the gain of the reverse amplifier circuit cannot be adjusted, but when the resistor RN is a variable resistance resistor such as a sliding resistor, the gain of the reverse amplifier circuit can still be adjusted.

[0040] The signal conditioning circuit 103 connected between the operational amplifier circuit 102 and the signal processing control circuit 104 is used to filter and zero the signal output by the operational amplifier circuit 102. The operational amplifier circuit 102 includes at least one filtering circuit and a zeroing circuit. The filtering circuit is used to filter out the high-frequency interference of the external environmental disturbance on the TMR tunnel magnetoresistive sensor 108. The zeroing circuit is used to adjust the filtered signal when there is no residual current input, so that the output voltage thereof is the reference voltage, avoiding the output zero drift caused by the accuracy problem of the components themselves, and the signal output after zeroing is connected to the ADC interface of the signal processing control circuit 104, and the signal processing control circuit 104 performs AD signal conversion.

[0041] The filter circuit in the signal conditioning circuit 103 is preferably an active filter circuit. Figure 3 A specific active filter circuit is provided, the active filter circuit comprising an operational amplifier U2A, a capacitor C2, a capacitor C3, a resistor R12 and a resistor R13, the positive input terminal of the operational amplifier U2A is connected to one end of the capacitor C3 and one end of the resistor R13, the reverse input terminal of the operational amplifier U2A is connected to one end of the capacitor C2, the reverse input terminal of the operational amplifier U2A is connected to the output terminal of the operational amplifier U2A, the output terminal of the operational amplifier U2A is connected to the input terminal of the zero adjustment circuit, the other end of the capacitor C2 and the other end of the resistor R13 are connected to one end of the resistor R12, the other end of the resistor R12 is connected to the output terminal of the operational amplifier circuit 102, and the other end of the capacitor C3 is connected to GND.

[0042] An analog test circuit 106 is also provided between the residual current detection sensor 112 and the signal processing circuit 113. The analog test circuit 106 is used to test the reliability of the device. The analog test winding 111 of the analog test circuit 106 is wound on the magnetic ring 109. The analog test circuit 106 is connected to the signal processing control circuit 104 and is controlled by the signal processing control circuit 104 to generate an analog residual current signal for reliability testing. The analog residual current signal is preferably generated periodically by the signal processing control circuit 104. The analog residual current signal is used to detect the action characteristics of the device to ensure that a product failure can be discovered in time, thereby improving the reliability of the product.

[0043] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A residual current detection device based on TMR tunnel magnetoresistance, characterized in that: The invention comprises a residual current detection sensor (112), a signal processing circuit (113), and a power supply circuit (101) for supplying power to the residual current detection sensor (112) and the signal processing circuit (113); the output end of the residual current detection sensor (112) is connected to the input end of the signal processing circuit (113); the residual current detection sensor (112) comprises a TMR tunnel magnetoresistive sensor (108); and the signal processing circuit (113) comprises an operational amplifier circuit (102), a signal conditioning circuit (103), a temperature signal acquisition circuit (105), a signal processing control circuit (104), and a tripping execution circuit (107) which are connected in sequence; The input end of the operational amplifier circuit (102) is connected to the output end of the TMR tunnel magnetoresistive sensor (108) and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor (108); the signal conditioning circuit (103) is used to filter and zero the signal output by the operational amplifier circuit (102); the temperature signal acquisition circuit (105) is used to detect the ambient temperature; the input end of the signal processing control circuit (104) is respectively connected to the output ends of the signal conditioning circuit (103) and the temperature signal acquisition circuit (105); the signal processing control circuit (104) performs compensation processing on the received signal in combination with a preset temperature change compensation model; after the residual current exceeds a threshold value preset by the signal processing control circuit (104), the signal processing control circuit (104) outputs a trigger signal to the tripping execution circuit (107) to activate the tripping execution circuit (107); The residual current detection sensor (112) further comprises a shielding device (110), a circuit board (114) and a magnetic focusing ring (109); the TMR tunnel magnetoresistance sensor (108) is supported on the surface of the circuit board (114), and the TMR tunnel magnetoresistance sensor (108) is arranged perpendicular to the direction of the magnetic field in the magnetic focusing ring (109); the shielding device (110) is arranged around the magnetic focusing ring (109) to shield the influence of external interference on the TMR tunnel magnetoresistance sensor (108); It also includes an analog test circuit (106) for performing reliability testing, wherein the analog test winding (111) of the analog test circuit (106) is wound around a magnetic focusing ring (109), and the analog test circuit (106) is connected to a signal processing control circuit (104) and is controlled by the signal processing control circuit (104) to generate an analog residual current signal for performing reliability testing; The residual current detection sensor (112) is of an annular structure, the circuit board (114) is annular, the annular magnetic focusing ring (109) is stacked in parallel with the circuit board (114), a magnetic focusing ring gap is provided on the radial outer wall of the magnetic focusing ring (109), and the magnetic focusing ring gap penetrates the side surface of the magnetic focusing ring (109) facing the circuit board (114), a connecting plate is provided on the circuit board (114) and vertically protrudes from the circuit board (114), a TMR tunnel magnetoresistive sensor (108) is provided on the side of the connecting plate, and the TMR tunnel magnetoresistive sensor (108) and the connecting plate extend into the magnetic focusing ring gap.

2. A residual current detection device based on TMR tunnel magnetoresistance according to claim 1, characterized in that: The operational amplifier circuit (102) comprises a differential operational amplifier circuit and an inverse amplifier circuit. The input end of the differential operational amplifier circuit is connected to the output end of the TMR tunnel magnetoresistive sensor (108) and is used to amplify the signal output by the TMR tunnel magnetoresistive sensor (108). The inverse amplifier circuit is connected to the differential operational amplifier circuit and performs amplification processing with a selectable gain on the output signal of the differential operational amplifier circuit.

3. The residual current detection device based on TMR tunnel magnetoresistance according to claim 2, characterized in that: An analog conversion switch S1 is connected between the operational amplifier circuit (102) and the signal processing control circuit (104). Under the control of the signal processing control circuit (104), the analog conversion switch S1 selectively adjusts the gain of the reverse amplifier circuit.

4. A residual current detection device based on TMR tunnel magnetoresistance according to claim 2 or 3, characterized in that: The operational amplifier circuit (102) comprises an operational amplifier, and a reference voltage of the operational amplifier circuit (102) is half of a power supply voltage of the operational amplifier.

5. The residual current detection device based on TMR tunnel magnetoresistance according to claim 1, characterized in that: The signal conditioning circuit (103) comprises at least one filtering circuit and a zero adjustment circuit. The filtering circuit is an active filtering circuit, which is used to filter out high-frequency interference generated by the external environment on the TMR magnetoresistive sensor. The output end of the zero adjustment circuit is connected to the signal processing control circuit (104) and is used to adjust and process the signal filtered by the active filtering circuit and output a reference voltage when there is no residual current input.

6. A residual current detection device based on TMR tunnel magnetoresistance according to claim 5, characterized in that: The active filter circuit comprises an operational amplifier U2A, a capacitor C2, a capacitor C3, a resistor R12 and a resistor R13, the positive input end of the operational amplifier U2A is connected to one end of the capacitor C3 and one end of the resistor R13, the reverse input end of the operational amplifier U2A is connected to one end of the capacitor C2, the reverse input end of the operational amplifier U2A is connected to the output end of the operational amplifier U2A, the output end of the operational amplifier U2A is connected to the input end of the zero adjustment circuit, the other end of the capacitor C2 and the other end of the resistor R13 are connected to one end of the resistor R12, the other end of the resistor R12 is connected to the output end of the operational amplifier circuit (102), and the other end of the capacitor C3 is connected to GND.

7. The residual current detection device based on TMR tunnel magnetoresistance according to claim 2, characterized in that: The differential operational amplifier circuit comprises a resistor R5, a resistor R6, a resistor R9, a resistor R10 and an operational amplifier U1A, wherein the positive input end of the operational amplifier U1A is connected to one end of the resistor R10 and the resistor R9, the negative input end of the operational amplifier U1A is connected to one end of the resistor R6 and the resistor R5, the other end of the resistor R5 is connected to the output end of the operational amplifier U1A, the other end of the resistor R6 is connected to the residual current detection sensor (112) as the positive pole of the input end of the operational amplifier circuit (102), the other end of the resistor R9 is connected to the residual current detection sensor (112) as the negative pole of the input end of the operational amplifier circuit (102), and the other end of the resistor R10 is connected to the power supply circuit (101); The reverse amplifier circuit comprises a resistor RN, a resistor R7, a resistor R8, a resistor R11, a capacitor C1 and an operational amplifier U1B, wherein the positive input end of the operational amplifier U1B is connected to one end of the resistor R11, the reverse input end of the operational amplifier U1B is connected to one end of the resistor R7 and one end of the resistor RN, the output end of the operational amplifier U1B is connected to one end of the resistor R8 and the other end of the resistor RN, the other end of the resistor R7 is connected to the output end of the operational amplifier U1A, the other end of the resistor R11 is connected to a power supply circuit (101), the other end of the resistor R8 is connected to one end of the capacitor C1 and a signal conditioning circuit (103), and the other end of the capacitor C1 is connected to GND.

8. The residual current detection device based on TMR tunnel magnetoresistance according to claim 3, characterized in that: The differential operational amplifier circuit comprises a resistor R5, a resistor R6, a resistor R9, a resistor R10 and an operational amplifier U1A, wherein the positive input end of the operational amplifier U1A is connected to one end of the resistor R10 and the resistor R9, the negative input end of the operational amplifier U1A is connected to one end of the resistor R6 and the resistor R5, the other end of the resistor R5 is connected to the output end of the operational amplifier U1A, the other end of the resistor R6 is connected to the residual current detection sensor (112) as the positive pole of the input end of the operational amplifier circuit (102), the other end of the resistor R9 is connected to the residual current detection sensor (112) as the negative pole of the input end of the operational amplifier circuit (102), and the other end of the resistor R10 is connected to the power supply circuit (101); The reverse amplification circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R7, a resistor R8, a resistor R11, a capacitor C1, an operational amplifier U1 B and an analog conversion switch S1, wherein the common end of the analog conversion switch S1 is connected to the reverse input end of the operational amplifier U1 B, the other end of the analog conversion switch S1 can be selectively connected to any one end of the resistor R1, the resistor R2, the resistor R3 and the resistor R4, and the other ends of the resistors R1, R2, R3 and R4 are all connected to the output end of the operational amplifier U1B; The positive input terminal of the operational amplifier U1B is connected to one end of the resistor R11, the negative input terminal of the operational amplifier U1B is connected to one end of the resistor R7, the output terminal of the operational amplifier U1B is connected to one end of the resistor R8, the other end of the resistor R7 is connected to the output terminal of the operational amplifier U1A, the other end of the resistor R11 is connected to the power supply circuit (101), the other end of the resistor R8 is connected to one end of the capacitor C1 and the signal conditioning circuit (103), and the other end of the capacitor C1 is connected to GND.

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