Non-intrusive micro-current sensor

Abstract

The utility model provides a non-intrusive micro-current sensor, which is characterized in that the non-intrusive micro-current sensor comprises a top cover and a base, the top cover and the base are connected through a rotating shaft at the rear end, and the top cover can be opened from the base; the top cover and the base are locked through a bayonet structure at the front end after being closed; a wireless communication antenna is assembled on the outer surface of the top cover; wire guiding and limiting grooves are designed in the top cover and the base in the transverse axis direction. Magnetic shielding coatings are arranged on the outer surfaces of the top cover and the base; a current detection unit, a circuit board and a battery are assembled in the base. The non-intrusive current sensor provided by the utility model is small in size and convenient to use and operate, is installed in a clamping manner during use, and does not need to be changed, damaged or intruded into a detected cable.

Description

Technical Field

[0001] This utility model relates to current sensing devices, and more particularly to non-invasive weak current sensors, which are suitable for non-invasive online monitoring of elevator control signals and drive signals. Background Technology

[0002] Non-intrusive elevator maintenance is a novel maintenance strategy designed to ensure that elevators can be inspected and their operational status monitored without stopping operation. This not only improves safety but also helps reduce downtime. One of the keys to achieving this goal is current signal monitoring technology, which determines the equipment's operating status and faults by monitoring the current signals on the elevator's control and drive signal lines in real time.

[0003] Current monitoring technology primarily relies on the application of current sensors. These sensors can collect real-time current data on elevator control and drive signal lines, such as the door opening / closing control lines and the traction machine current. By analyzing this data, the system can identify the normal operating mode of the equipment and detect any anomalies. For example, if a sudden current fluctuation occurs during elevator operation, the system can respond quickly, safely stopping the elevator and reducing the risk of injury. Such a system not only helps in the timely detection of faults but also enables predictive maintenance, ensuring the elevator is always in optimal working condition.

[0004] To meet the growing demands in terms of application scenarios, installation methods, and maintenance complexity, current detection devices have been continuously evolving towards smaller size, lower power consumption, lower cost, easier installation, and greater intelligence. Due to the advantages of non-contact, high isolation, and strong environmental adaptability, magnetic field measurement has received increasing research and application as a major non-invasive current detection technology in recent years. Commonly used magnetic sensors are mainly based on the Hall effect and various magnetoresistive effects. Among them, TMR current sensors based on the tunneling magnetoresistance (TMR) effect exhibit high sensitivity, wide bandwidth response, and high reliability. Compared to other types of magnetoresistive elements such as AMR and GMR, their magnetoresistance change rate at room temperature is far greater than other types of magnetoresistive elements because there is no antiferromagnetic coupling effect in their ferromagnetic layer. Compared to the more commonly used Hall current sensors, they offer superior dynamic range, sensitivity, and resolution. Their higher magnetoresistance change rate and wider bandwidth make them widely used in current monitoring.

[0005] Currently used non-invasive current sensors have significant limitations when facing large-scale engineering deployments. Since the magnetic field generated by cable current is spatially distributed, the relative position of the magnetic field sensor and the cable significantly affects the current measurement results. Therefore, to improve measurement accuracy, current market products generally employ magnetic cores or other magnetically focused structures to confine the spatial distribution of the magnetic field, or use arrays of multiple multi-axis magnetic sensors with complex conversion algorithms to determine the measured current value. However, introducing magnetic core structures leads to bulky and heavy equipment, and often requires modifications to the electrical wiring during use. Furthermore, increasing the number of sensors and their axial orientation significantly increases sensor cost, power consumption, and size; the circular layout of the loop also increases the system size. Therefore, the key to solving the problems of size, power consumption, and cost in non-invasive magnetic field current measurement devices lies in achieving non-invasive current detection without using magnetically focused structures or relying on magnetic sensor arrays.

[0006] This invention addresses current market demands by proposing a non-invasive micro-current sensor. The sensor employs a coreless clamping structure with a magnetic shielding coating, resulting in a compact size and convenient deployment. Based on a single-axis TMR magnetic sensor, it achieves non-invasive online detection of weak currents. Implementing this invention can reduce the size, power consumption, and cost of elevator online monitoring systems, facilitating large-scale deployment. Utility Model Content

[0007] This invention proposes a non-invasive microcurrent sensor, which includes a top cover and a base connected by a pivot at the rear end. The top cover can be lifted off the base. After the top cover and base are closed, they are locked by a bayonet structure at the front end. A wireless communication antenna is mounted on the outer surface of the top cover. Wire guide and limiting grooves are designed along the transverse axis inside the top cover and base. The outer surfaces of the top cover and base have a magnetic shielding coating. A current detection unit, a circuit board, and a battery are mounted inside the base.

[0008] The current detection unit includes a tunneling magnetoresistive (TMR) current sensing unit and a differential amplifier circuit, which are electrically connected through PCB signal lines. Its upper surface is the detection surface of the TMR current sensing unit.

[0009] The wire guiding and limiting groove includes a top cover portion and a base portion; the top cover portion includes a base and multiple limiting clips embedded in the base; the top of the base has a first arc-shaped concave surface for guiding the direction of the signal line under test; the top of the limiting clip has a second arc-shaped concave surface for pressing and limiting the relative position of the signal line under test and the detection surface of the tunneling magnetoresistive (TMR) current sensing unit; the wire guiding and limiting groove of the base portion is located on both sides of the tunneling magnetoresistive (TMR) current sensing unit and has a third arc-shaped concave surface.

[0010] The bottom of the limiting card is supported by a spring.

[0011] The current detection unit and the circuit board are connected by a data cable, the battery and the circuit board are connected by a power cable, and the circuit board is connected to the wireless communication antenna via an RF flexible cable and a coaxial connector mounted on the top cover.

[0012] The circuit board includes a power management circuit, a wireless interface circuit, a microprocessor, and an AD conversion circuit.

[0013] The power management circuit, wireless interface circuit, microprocessor, and AD conversion circuit are integrated into a single chip, which is a low-power Bluetooth chip or a microcontroller chip that provides a 433MHz wireless interface.

[0014] The wireless communication antenna is a small-sized microstrip antenna with a ceramic substrate.

[0015] The present invention proposes a clamping structure for a current sensor with no magnetic core and a magnetic shielding coating. It is compact, easy to deploy, and achieves non-invasive online detection of weak currents based on a single-axis TMR magnetic sensor.

[0016] Other features and advantages of this utility model will become clearer after reading the detailed description of the embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0017] To clearly illustrate the technical solution and embodiments of this utility model, the accompanying drawings are briefly described below. It should be noted that the drawings are primarily intended to explain the interconnections, structural features, and advantages of the various components of the device, and are not drawn to scale according to the actual dimensions of the device. Obviously, the drawings only relate to a limited set of embodiments and should not be construed as limiting the present utility model. Those skilled in the art can easily obtain new embodiments through formal variations based on these drawings.

[0018] Figure 1 This is a schematic diagram of the external structure of one embodiment of the present utility model;

[0019] Figure 2 This is a schematic diagram of the internal structure of the top cover after opening one embodiment of the present invention;

[0020] Figure 3 This is a schematic diagram of the wire limiter structure according to an embodiment of the present invention. Detailed Implementation

[0021] The specific embodiments of this utility model are described in detail below with reference to the accompanying drawings.

[0022] This invention proposes a non-invasive microcurrent sensor, the external structure of which is as follows: Figure 1As shown. The non-invasive microcurrent sensor includes a top cover A1 and a base A2, which are connected by a rear pivot A3 and locked by a bayonet structure A4 when closed. A wireless communication antenna A5 is mounted on the surface of the top cover A1. Wire guide and limiting grooves A6 are designed along the transverse axis of the top cover A1 and the base A2. In use, the top cover is first opened, allowing the signal line to be tested to run along the guide and limiting grooves. Then, the top cover is closed and locked by the bayonet mechanism A4, straightening and tightening the signal line to be tested in the wire guide and limiting grooves A6.

[0023] Figure 2 A top view of the non-invasive microcurrent sensor after the top cover is opened is further provided.

[0024] The base B1, which has the wire guide and limiting groove on the inner side of the top cover, has a first arc-shaped concave surface on its top to guide the direction of the signal line to be tested; multiple limiting clips B2 are assembled along the axis, with a second arc-shaped concave surface on their top to press and limit the lateral position of the signal line to be tested. A current detection unit B3 is mounted in the middle of the transverse axis inside the base A2. This unit includes a tunneling magnetoresistance (TMR) current sensing unit and a differential amplifier circuit, which are electrically connected via PCB signal lines. Its upper surface is the detection surface of the TMR current sensing unit, and its two sides are the portions of the wire guide and limiting groove located in the base. These sections have a third arc-shaped concave surface, the bottom of which is flush with the upper surface of the current detection unit B3. A circuit board is installed between the wire guide and limiting groove and the rotating shaft, connected to the output of the differential amplifier circuit via a data cable, and connected to the wireless communication antenna A5 via an RF flexible cable and an RF coaxial connector mounted on the top cover. A battery unit is installed on the other side of the wire guide and limiting groove, connected to the circuit board via a power cable. The circuit board includes a power management circuit, a wireless interface circuit, a microprocessor, and an AD conversion circuit. These components are integrated into a single chip, which is either a low-power Bluetooth chip or a microcontroller chip providing a 433MHz wireless interface.

[0025] Figure 3 A longitudinal sectional view of the limiting card B2 is further provided. As can be seen from the figure, the limiting card B2 is embedded in the base B1, and its bottom is supported by a spring to press the signal line to be tested and limit its lateral position.

[0026] The outer surfaces of the top cover A1 and the base A2 are coated with a magnetic shielding coating to prevent external magnetic fields from affecting the measurement.

[0027] The wireless communication antenna A5 is a small-sized microstrip antenna with a ceramic substrate.

[0028] In use, the above embodiments of this utility model ensure that the signal line under test is in a long and straight position through the wire guide and limiting groove, and the limiting card presses the signal line under test to ensure that it is close to and parallel to the detection surface of the TMR current sensing unit. The relative positional relationship between the two remains stable after installation and will not change due to general mechanical disturbances. When current flows through the signal line under test (long straight wire), a surrounding magnetic field is generated, and the magnetic field strength is proportional to the magnitude of the current under test. The TMR current sensing unit detects the magnetic field and converts it into a differential voltage signal, which is output to the differential amplifier circuit. After amplification, the differential voltage signal is sent to the AD conversion circuit on the circuit board through a cable to be converted into a digital signal. This digital signal is further processed by the microprocessor and mapped into a detected current value. Finally, the current detection result is sent to the host computer through the wireless interface for further business processing.

[0029] The non-invasive current sensor proposed in this utility model is small in size and easy to use. It is installed by clamping without altering, damaging or intruding into the cable being tested.

[0030] The description of this utility model is given for illustrative purposes only and is not intended to be exhaustive or to limit the utility model to the disclosed forms. The embodiments were chosen and described to better illustrate the principles and practical applications of the utility model, and to enable those skilled in the art to understand the utility model and design various embodiments with various modifications suitable for a particular purpose. All new embodiments that fall within the basic concept, construction principles, and spirit of this utility model, and are achieved through simple variations, modifications, equivalent substitutions, or improvements, should be included within the scope of protection of this utility model. The scope of this utility model is defined by the appended claims.

Claims

1. A non-invasive microcurrent sensor, characterized in that, The non-invasive microcurrent sensor includes a top cover and a base, which are connected by a pivot at the rear end. The top cover can be lifted off the base. After the top cover and base are closed, they are locked by a bayonet structure at the front end. A wireless communication antenna is mounted on the outer surface of the top cover. Wire guide and limiting grooves are designed along the transverse axis inside the top cover and base. The outer surfaces of the top cover and base have a magnetic shielding coating. A current detection unit, circuit board, and battery are mounted inside the base.

2. The non-invasive microcurrent sensor according to claim 1, characterized in that, The current detection unit includes a tunneling magnetoresistive (TMR) current sensing unit and a differential amplifier circuit, which are electrically connected through PCB signal lines. Its upper surface is the detection surface of the TMR current sensing unit.

3. The non-invasive microcurrent sensor according to claim 1, characterized in that, The wire guiding and limiting groove includes a top cover portion and a base portion; the top cover portion includes a base and multiple limiting clips embedded in the base; the top of the base has a first arc-shaped concave surface for guiding the direction of the signal line under test; the top of the limiting clip has a second arc-shaped concave surface for pressing and limiting the relative position of the signal line under test and the detection surface of the tunneling magnetoresistive (TMR) current sensing unit; the wire guiding and limiting groove of the base portion is located on both sides of the tunneling magnetoresistive (TMR) current sensing unit and has a third arc-shaped concave surface.

4. The non-invasive microcurrent sensor according to claim 3, characterized in that, The bottom of the limiting card is supported by a spring.

5. The non-invasive microcurrent sensor according to claim 1, characterized in that, The current detection unit and the circuit board are connected by a data cable, the battery and the circuit board are connected by a power cable, and the circuit board is connected to the wireless communication antenna via an RF flexible cable and a coaxial connector mounted on the top cover.

6. The non-invasive microcurrent sensor according to claim 1, characterized in that, The circuit board includes a power management circuit, a wireless interface circuit, a microprocessor, and an AD conversion circuit.

7. The non-invasive microcurrent sensor according to claim 6, characterized in that, The power management circuit, wireless interface circuit, microprocessor, and AD conversion circuit are integrated into a single chip, which is a low-power Bluetooth chip or a microcontroller chip that provides a 433MHz wireless interface.

8. The non-invasive microcurrent sensor according to any one of claims 1-7, characterized in that, The wireless communication antenna is a small-sized microstrip antenna with a ceramic substrate.

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