CN116990539A - Excitation circuit for electromagnetic log - Google Patents
Excitation circuit for electromagnetic log Download PDFInfo
- Publication number
- CN116990539A CN116990539A CN202310968995.XA CN202310968995A CN116990539A CN 116990539 A CN116990539 A CN 116990539A CN 202310968995 A CN202310968995 A CN 202310968995A CN 116990539 A CN116990539 A CN 116990539A
- Authority
- CN
- China
- Prior art keywords
- circuit
- capacitor
- excitation
- pass filter
- exciting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000005284 excitation Effects 0.000 title claims abstract description 69
- 239000003990 capacitor Substances 0.000 claims abstract description 57
- 230000003321 amplification Effects 0.000 abstract description 4
- 238000013461 design Methods 0.000 abstract description 4
- 238000003199 nucleic acid amplification method Methods 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 3
- 238000001914 filtration Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000010752 BS 2869 Class D Substances 0.000 description 1
- 101001053263 Homo sapiens Insulin gene enhancer protein ISL-1 Proteins 0.000 description 1
- 102100024392 Insulin gene enhancer protein ISL-1 Human genes 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005059 dormancy Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/50—Devices characterised by the use of electric or magnetic means for measuring linear speed
- G01P3/54—Devices characterised by the use of electric or magnetic means for measuring linear speed by measuring frequency of generated current or voltage
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P1/00—Details of instruments
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/042—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using digital processors
- G05B19/0423—Input/output
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Automation & Control Theory (AREA)
- Amplifiers (AREA)
Abstract
The invention discloses an excitation circuit for an electromagnetic log, which comprises an MCU circuit, a PWM power amplification circuit, an LC filter circuit, a resonant circuit, an excitation acquisition circuit and an electromagnetic sensor. The invention can select different electromagnetic sensors matched with different resonance capacitors, realizes the universal design of the exciting circuit, has overcurrent protection and overheat protection functions, realizes the constant current output of exciting current through current closed-loop control, and improves the testing requirement of the system through exciting voltage detection.
Description
Technical Field
The invention relates to the technical field of electromagnetic speed measurement, in particular to an excitation circuit for an electromagnetic log.
Background
At present, the traditional excitation mode of the electromagnetic log generally adopts 50Hz and 220V ship electricity to obtain a certain voltage through voltage reduction of a transformer to excite a coil winding of a sensor, so that a 50Hz alternating magnetic field is generated near an electrode of the sensor, and the frequency and the voltage of excitation current are easily influenced by fluctuation of a power grid by adopting the excitation mode; the alternating current potential signal of the sensor for sensing the flow rate is easy to be interfered by 50Hz power frequency, so that difficulty is brought to the processing of a rear-end signal, and the zero position of the sensor is also difficult to be reduced; after the sensor is replaced, the impedance of different sensors is inconsistent, so that the exciting current of the coil can also change correspondingly, the problems above easily cause inaccurate speed measurement, and the log cannot work normally when serious.
By adopting the linear power amplification excitation technology, the zero position of the sensor can be effectively reduced, the excitation frequency and the current are kept constant, the influence of power grid fluctuation and sensor impedance change is avoided, the power frequency interference of the system is reduced, but the linear power amplification has larger heating value and low efficiency, the heat dissipation design is needed, and the complexity of the system is increased.
Therefore, how to improve the applicability and flexibility of the excitation circuit is a problem that needs to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, the invention provides an excitation circuit applied to an electromagnetic log, which can improve the efficiency of a system, is applicable to different electromagnetic sensors, and has wide applicability and flexibility.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
an excitation circuit for an electromagnetic log comprises an MCU circuit, a D-type power amplifier circuit, an LC filter circuit, a resonance capacitor circuit, an excitation current acquisition circuit, an excitation voltage acquisition circuit and an electromagnetic sensor which are connected in sequence; the LC filter circuit comprises a first low-pass filter circuit and a second low-pass filter circuit; the first low-pass filter circuit is connected to the exciting current acquisition circuit through the resonance capacitor circuit, and the output of the second low-pass filter circuit is directly connected to the exciting voltage acquisition circuit; the exciting current acquisition circuit is connected with the exciting voltage acquisition circuit through a resistor R1, and the exciting current acquisition circuit and the exciting voltage acquisition circuit are respectively connected to two ends of the electromagnetic sensor.
The technical effect of the technical scheme is that the MCU circuit can generate PWM pulse width modulation signals which are used for controlling the frequency and the magnitude of the exciting voltage of the electromagnetic sensor; the class D power amplifier circuit amplifies the PWM pulse width modulation signal output by the MCU circuit and outputs a PWM signal; the LC filter circuit carries out low-pass filtering on the PWM signal after power amplification, and generates a sine excitation voltage signal required by the electromagnetic sensor after filtering.
Preferably, the electromagnetic sensor is used as a load of an excitation circuit of the electromagnetic log, the load is equivalent to series connection of an inductor and a resistor in a circuit, the equivalent inductor in the electromagnetic sensor and a resonant capacitor circuit are subjected to series resonance to form a pure resistive sensor loop, and reactive compensation is performed on the inductor of the electromagnetic sensor, so that the excitation voltage of the sensor is reduced under the same working current, and reactive loss is reduced; the equivalent resistor in the electromagnetic sensor is connected with the second low-pass filter circuit.
Preferably, the MCU circuit and the class D power amplifier circuit are connected with the OTW pin through PWM, RESET, FAULT.
Preferably, the first low-pass filter circuit and the second low-pass filter circuit both comprise an inductor and a capacitor, one end of the inductor is connected in series with one end of the capacitor, the other end of the inductor is connected with the class D power amplifier circuit, and the other end of the capacitor is grounded; the output end of the first low-pass filter circuit is connected to the resonant capacitor circuit, and the series node of the second low-pass filter circuit is connected with the exciting voltage acquisition circuit.
Preferably, the resonant capacitor circuit comprises three groups of series circuits consisting of jumper wires and capacitors, wherein the jumper wires and the capacitors in each group of series circuits are connected in series, the three groups of series circuits are connected in parallel, the parallel input end is connected with a group of series nodes of the inductor and the capacitor in the first low-pass filter circuit, and the parallel output end is connected with the exciting current acquisition circuit.
Preferably, the excitation acquisition circuit comprises an excitation current acquisition circuit and an excitation voltage acquisition circuit;
the exciting current acquisition circuit comprises a capacitor, a resistor and a current transformer, wherein the capacitor and the resistor are connected in parallel, one end of the capacitor is connected with a first pin of the MCU circuit and the current transformer in parallel, and the other end of the capacitor is connected with the node in parallel to be grounded; the second pin of the current transformer is grounded, the third pin is connected with the parallel output end of the resonant capacitor circuit and one end of the resistor R1, and the fourth pin is connected with the inductor of the electromagnetic sensor;
the excitation voltage acquisition circuit comprises a capacitor, a resistor and a voltage transformer, wherein the capacitor and the resistor are connected in parallel, one end of the capacitor is connected with a first pin of the MCU circuit and the voltage transformer in parallel, and the other end of the capacitor is connected with the node in parallel to be grounded; the second pin of the voltage transformer is grounded, the third pin is connected with the other end of the resistor R1, and the fourth pin is connected with a group of series nodes of the second low-pass filter circuit and the resistor of the electromagnetic sensor. The exciting current acquisition circuit can acquire exciting current of the electromagnetic sensor through a current transformer, so that closed-loop control of the exciting current is realized; and after the resistor R1 is connected with the voltage transformer in series, the two ends of the electromagnetic sensor are connected in parallel and are used for detecting the excitation voltage of the electromagnetic sensor.
Compared with the prior art, the invention discloses an excitation circuit for an electromagnetic log, which is characterized in that PWM signals are generated through an MCU circuit, amplified by a D-type power amplifier, and then subjected to LC low-pass filtering by an LC filter circuit to generate sine excitation voltage signals with required frequency and size, the excitation voltage signals drive an electromagnetic sensor to work after passing through a resonance capacitor circuit, and the resonance capacitor circuit and the equivalent inductance of the electromagnetic sensor perform series resonance, so that the excitation voltage required by the excitation current with the same size is obviously reduced, the requirement of system power supply voltage is reduced, the excitation voltage is adapted to different sensors through different resonance capacitors, and the excitation current is constant through closed loop control. The exciting frequency and the exciting voltage of the circuit are adjustable, the exciting voltage of the electromagnetic sensor is reduced through the series resonant circuit, and the efficiency of the system is improved. Meanwhile, exciting current is acquired through an exciting current acquisition circuit, and PWM signals of the MCU are automatically adjusted according to the set current, so that the output of a class D power amplifier is controlled, the closed-loop control of the exciting current is realized, and the constant current of the exciting current of the system can be ensured; the exciting voltage acquisition circuit detects exciting voltage of the electromagnetic sensor, and realizes an on-line diagnosis function. The invention is applicable to different electromagnetic sensors and has wide applicability and flexibility.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an excitation circuit for an electromagnetic log according to the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The embodiment of the invention discloses an excitation circuit for an electromagnetic log, which is shown in figure 1 and comprises an MCU circuit 1, a class D power amplifier circuit 2, an LC filter circuit 3, a resonance capacitor circuit 4, an excitation current acquisition circuit 5, an excitation voltage acquisition circuit 6 and an electromagnetic sensor 7; the LC filter circuit 3 includes a first low-pass filter circuit and a second low-pass filter circuit; .
The MCU circuit 1 is used for generating PWM pulse width modulation signals, the PWM pulse width modulation signals are amplified by the D-type power amplifier circuit 2 and then are subjected to LC low-pass filtering by the first low-pass filter circuit and the second low-pass filter circuit to generate sinusoidal excitation voltage signals with required frequency and size, the excitation voltage signals of the first low-pass filter circuit drive the electromagnetic sensor to work after passing through the resonance capacitor circuit 4, and the equivalent inductance of the resonance capacitor circuit 4 and the electromagnetic sensor 7 are used for carrying out series resonance, so that the excitation voltage required by the excitation current with the same size is output, the requirement of system power supply voltage is reduced, the excitation current is adapted to different sensors through different resonance capacitors, and the second low-pass filter circuit is also used for realizing the excitation current constant through the excitation current acquisition circuit 5 and the excitation voltage acquisition circuit 6 by closed loop control.
Example 2
In one embodiment of the present invention, in one embodiment,
the MCU in the MCU circuit 1 can select an ARM chip with an AD sampling function, the ARM chip outputs PWM pulse width modulation signals with certain carrier frequency, the carrier frequency is determined according to the class D power amplifier circuit 2, and the carrier frequency is not more than the maximum switching frequency of the class D power amplifier circuit 2.
The frequency and the amplitude of the sinusoidal excitation voltage to be obtained are determined by the PWM pulse width modulation signal, the frequency and the amplitude of the sinusoidal excitation voltage can be controlled by controlling the MCU circuit 1 through software to adjust the PWM pulse width modulation signal, the ARM chip simultaneously acquires the excitation current and the excitation voltage of the electromagnetic sensor 7 through the excitation current acquisition circuit 5 and the excitation voltage acquisition circuit 6 respectively, the PWM pulse width modulation signal is adjusted through the acquired excitation current to realize the excitation current closed-loop control, so that the constant current output of the sensor can be realized, the excitation voltage of the electromagnetic sensor is detected through the excitation voltage acquisition circuit to meet the requirement, and the on-line detection function of the excitation circuit is realized. Meanwhile, the ARM chip controls the work and dormancy of the class D power amplifier through the high and low levels of the RESET pin signal.
And the class D power amplifier circuit 2 is selected from DRV8412 chips of TI company, the working efficiency of the chips can reach 97%, the DRV8412 chips amplify the input PWM signals, the DRV8412 has a two-channel output function, the maximum current can reach 2X 3A, and the working current requirement of an electromagnetic sensor of the electromagnetic log is met. The DRV8412 chip is provided with an overheat and overcurrent alarm power amplifier, and the overheat and overcurrent alarm power amplifier is output to the ARM chip through a FAULT signal wire and an OTW signal wire, and the ARM chip can monitor the working state of the D-type power amplifier in real time, so that the on-line monitoring of the power amplifier is realized. The maximum switching frequency of DRV841 chip can reach 500kHz.
The LC filter circuit 3 filters out the high frequency component of the signal by LC low pass filtering according to the principle of PWM pulse width modulation circuit to obtain the sinusoidal excitation voltage signal of the desired frequency. The cut-off frequency of the LC filter isL1 is the inductance value of the filter, C1 is the capacitance value of the filter, two groups of inductances included in the LC filter circuit 3 are L1 and L2 respectively, two groups of capacitances are C1 and C2 respectively, and L1=L2, C1=C2, L1 and C1 form a first low-pass filter circuit, L2 and C2 form a second low-pass filter circuit, and in order to make the output sinusoidal excitation voltage achieve a better effect, the following relation needs to be satisfied: 10f 1 ＜f c ＜f s /10, where f 1 Is the fundamental frequency of sinusoidal excitation voltage 32Hz, f s Is the PWM carrier frequency 114kHz. Considering the relation of inductance and capacitance volume, f c When the value is about 7k, the value of L1 is 22uH, and the value of C1 is 22 uF.
The electromagnetic sensor 7 comprises an inductance L and a resistance R, which are connected in series, and the inductance L of the different sensors is different.
A resonant capacitor circuit 4 comprising jumpers X1, X2 and X3, capacitors C3, C4 and C5; c3, C4 and C5 are resonance capacitors, X1 and C3 are connected in series, X2 and C4 are connected in series, X3 and C5 are connected in series, and three groups of series circuits are connected in parallel. The size of the resonance capacitor is selected to be related to the size of the inductance L of the electromagnetic sensor, and the resonance capacitor and the inductance L form series resonance. The magnitude of exciting voltage can be reduced after resonance, reactive loss is reduced, and meanwhile, the input voltage of the class-D power amplifier circuit 2 can be reduced, so that the miniaturization design is facilitated. And different sensors can be adapted through jumpers such as X1, X2 and X3, and of course, X1, X2 and X3 can adopt a relay control mode to carry out remote communication with the MCU, so that the selection control of the relay is realized, and the purpose of matching different sensors is achieved.
The exciting current acquisition circuit 5 comprises a capacitor C6, a resistor R2 and current transformers T1, C6 and R2 which are connected in parallel, wherein one end of the exciting current acquisition circuit is connected with a first pin of an ARM chip and a first pin of an electromagnetic sensor in parallel, the other end of the exciting current acquisition circuit is connected with a ground GND through a parallel node, a second pin of the exciting current acquisition circuit T1 is connected with the ground, a third pin of the exciting current acquisition circuit is connected with a parallel node of C3, C4 and C5 and one end of the resistor R1, and a fourth pin of the exciting current acquisition circuit is connected with one end of an inductor L of the electromagnetic sensor. The current collection is realized by connecting the current transformer in series in the excitation circuit, so that the closed-loop control of the excitation current is realized, and the constant current output of the excitation current is realized.
The exciting voltage acquisition circuit 6 comprises a capacitor C7, a resistor R3 and a current transformer T2, wherein the capacitor C7 and the current transformer T2 are connected in parallel, one end of the exciting voltage acquisition circuit is connected with a first pin of an ARM chip and a first pin of an electromagnetic sensor in parallel, the other end of the exciting voltage acquisition circuit is connected with a grounding GND through a node in parallel, a second pin of the exciting voltage acquisition circuit T2 is grounded, a third pin of the exciting voltage acquisition circuit is connected with the other end of the resistor R1, and a fourth pin of the exciting voltage acquisition circuit is connected with a connecting node of an inductor L2 and a capacitor C2 in the LC filter circuit 3 and one end of a resistor R of the electromagnetic sensor. The voltage is collected by connecting a voltage transformer in parallel in the excitation loop, so that the excitation voltage is monitored on line.
The embodiment can realize the closed-loop control of the current of the electromagnetic log, realize constant current output and on-line detection of exciting voltage; the series resonance of the resonant capacitor and the electromagnetic sensor inductance coil is connected in series in the circuit to reduce the requirement of the system power supply. Meanwhile, different resonant capacitors can be selected to carry out series resonance with the sensor according to the inductance values of different sensors through jumper wire selection or relay selection functions, so that the universal design of the exciting circuit is realized.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. The exciting circuit for the electromagnetic log is characterized by comprising an MCU circuit, a D-type power amplifier circuit, an LC filter circuit, a resonance capacitor circuit, an exciting current acquisition circuit, an exciting voltage acquisition circuit and an electromagnetic sensor which are connected in sequence; the LC filter circuit comprises a first low-pass filter circuit and a second low-pass filter circuit;
the first low-pass filter circuit is connected to the exciting current acquisition circuit through the resonance capacitor circuit, and the output of the second low-pass filter circuit is directly connected to the exciting voltage acquisition circuit; the exciting current acquisition circuit is connected with the exciting voltage acquisition circuit through a resistor R1, and the exciting current acquisition circuit and the exciting voltage acquisition circuit are respectively connected to two ends of the electromagnetic sensor.
2. An excitation circuit for an electromagnetic log according to claim 1 wherein the electromagnetic sensor is equivalent to a series connection of an inductance and a resistance; the equivalent inductance in the electromagnetic sensor and the resonant capacitor circuit are subjected to series resonance to form a pure resistive sensor loop; the equivalent resistor in the electromagnetic sensor is connected with the second low-pass filter circuit.
3. The excitation circuit for an electromagnetic log according to claim 1 wherein the MCU circuit and the class D power amplifier circuit are connected by way of PWM, RESET, FAULT and OTW pins.
4. The excitation circuit for an electromagnetic log according to claim 1 wherein the first low pass filter circuit and the second low pass filter circuit each comprise an inductor and a capacitor, one end of the inductor is connected in series with one end of the capacitor, the other end of the inductor is connected to the class D power amplifier circuit, and the other end of the capacitor is grounded; the output end of the first low-pass filter circuit is connected to the resonant capacitor circuit, and the series node of the second low-pass filter circuit is connected with the exciting voltage acquisition circuit.
5. The excitation circuit for an electromagnetic log according to claim 4 wherein the resonant capacitor circuit comprises three sets of series circuits of jumpers and capacitors, each set of series circuits having a jumper and a capacitor connected in series, the three sets of series circuits being connected in parallel, the parallel input being connected to a series node of a set of inductors and capacitors in the first low pass filter circuit, the parallel output being connected to the excitation current collection circuit.
6. The excitation circuit for an electromagnetic log according to claim 5 wherein the excitation current collection circuit comprises a capacitor, a resistor and a current transformer, wherein the capacitor and the resistor are connected in parallel, one end of the parallel node is connected to the MCU circuit and the first pin of the current transformer, and the other end of the parallel node is grounded; the second pin of the current transformer is grounded, the third pin is connected with the parallel output end of the resonant capacitor circuit and one end of the resistor R1, and the fourth pin is connected with the inductor of the electromagnetic sensor;
the excitation voltage acquisition circuit comprises a capacitor, a resistor and a voltage transformer, wherein the capacitor and the resistor are connected in parallel, one end of the capacitor is connected with a first pin of the MCU circuit and the voltage transformer in parallel, and the other end of the capacitor is connected with the node in parallel to be grounded; the second pin of the voltage transformer is grounded, the third pin is connected with the other end of the resistor R1, and the fourth pin is connected with a group of series nodes of the second low-pass filter circuit and the resistor of the electromagnetic sensor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310968995.XA CN116990539A (en) | 2023-08-03 | 2023-08-03 | Excitation circuit for electromagnetic log |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310968995.XA CN116990539A (en) | 2023-08-03 | 2023-08-03 | Excitation circuit for electromagnetic log |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116990539A true CN116990539A (en) | 2023-11-03 |
Family
ID=88529694
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310968995.XA Pending CN116990539A (en) | 2023-08-03 | 2023-08-03 | Excitation circuit for electromagnetic log |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116990539A (en) |
-
2023
- 2023-08-03 CN CN202310968995.XA patent/CN116990539A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105190325B (en) | Resonance impedance sensing based on controlled negative impedance | |
| JP6304647B2 (en) | Current detector | |
| CN104934931A (en) | Residual current protection device | |
| CN205562653U (en) | Current inducer | |
| JP2002535863A (en) | Amplifier circuit | |
| CN105304303B (en) | A kind of accurate alterating and direct current current transformer | |
| CN213843381U (en) | Alternating voltage sampling and zero-crossing detection circuit based on current transformer | |
| EP2691783B1 (en) | Apparatus for current measurement | |
| CN101846702A (en) | Inductive current detection circuit | |
| CN206038762U (en) | Electron mutual -inductor | |
| KR20170110103A (en) | Electronic integrator for Rogowski coil sensor | |
| CN111398662A (en) | Current sensor for power transmission line | |
| CN104515931B (en) | A kind of DC leakage flow sensor based on magnetic modulation | |
| CN116990539A (en) | Excitation circuit for electromagnetic log | |
| CN111948438A (en) | Low-cost current sensor | |
| WO2020113467A1 (en) | Inductive magnetic sensor and electromagnetic exploration device | |
| CN212229025U (en) | Current sensor for power transmission line | |
| CN108375796A (en) | A kind of foreign matter detection system | |
| CN211374941U (en) | Cable insulation state monitoring device based on state perception | |
| CN105262331B (en) | A kind of heavy DC wave filter | |
| CN110554290B (en) | Cable insulation state monitoring device and monitoring method based on state sensing | |
| CN211577278U (en) | Automatic range alternating current parameter acquisition circuit | |
| CN210578435U (en) | Anti-noise optimization circuit for partial discharge signal of switch cabinet | |
| CN102857205B (en) | Signal conditioning device, sensor and signal acquiring processing system | |
| CN104749416A (en) | Electricity leakage detecting protecting circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |