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EP-4697031-B1 - PLANAR FLEXIBLE NON-INVASIVE CURRENT SENSOR WITH NON-MAGNETIC CORE

EP4697031B1EP 4697031 B1EP4697031 B1EP 4697031B1EP-4697031-B1

Inventors

  • GRNO, LADISLAV

Dates

Publication Date
20260513
Application Date
20240814

Claims (12)

  1. A planar flexible non-invasive current sensor, comprising a planar flexible core comprising at least one strip (2, 20) of non-magnetic metallic electrically conductive material, wherein the strips (2, 20) of the planar flexible core are electrically isolated from each other, wherein the planar flexible core is surrounded by at least one sensing planar structure (8, 80) from which it is electrically isolated, comprising transverse segments (6) of electrically conductive material electrically isolated above and below the planar flexible core, evenly spaced along the entire length of the planar flexible core, and wherein the transverse segments (6) are electrically conductively coupled in series with each other by connecting elements (5), thereby form the homogeneous winding, characterised in that the strip (2, 20) of the planar flexible core has the shape of a meander with constant effective width, wherein its longitudinal axis is parallel to the longitudinal axis of the planar flexible core.
  2. The planar flexible non-invasive current sensor according to claim 1, characterized in that at the ends of the planar flexible core there are arranged connecting openable means (3) for forming openable closed loops surrounding a current conductor (4) with the current to be measured.
  3. The planar flexible non-invasive current sensor according to any one of the preceding claims, characterized in that it comprises one sensing planar structure (8) and one planar flexible core formed by one strip (2), wherein the first end of the strip (2) and the first end of the sensing planar structure (8) are led out at the first end of the planar flexible core, and wherein the second end of the strip (2) and the second end of the sensing planar structure are electrically conductively connected at the second end of the planar flexible core.
  4. The planar flexible non-invasive current sensor according to any one of the preceding claims, characterized in that it comprises a first sensing planar structure (8) and a second sensing planar structure (80), wherein the first and second sensing planar structures (8, 80) are connected in series.
  5. The planar flexible non-invasive current sensor according to claim 4, characterized in that the transverse segments (6) of the first sensing planar structure (8) and the second sensing planar structure (80) are arranged alternately side by side, that their series connection is formed by electrically conductively connecting the end of the first sensing planar structure (8) to the beginning of the second sensing planar structure (80) by a first strip (2) of the planar flexible core, and the end of the second sensing planar structure (80) is led to the location of the beginning of the first sensing planar structure (8) by a second strip (20) of the planar flexible core, wherein the beginning of the first sensing planar structure (8) is the negative output of the sensor and the second strip (20) of the planar flexible core is the positive output of the sensor.
  6. The planar flexible non-invasive current sensor according to claim 5, characterized in that the first strip (2) of the planar flexible core is the reference output of the sensor.
  7. The planar flexible non-invasive current sensor according to any one of claims 1 to 4, characterized in that the transverse segments (6) of the first sensing planar structure (8) and the second sensing planar structure (80) are arranged on each side of the planar flexible core above each other in two different planes.
  8. The planar flexible non-invasive current sensor according to claim 7, characterized in that the transverse segments (6) of the first sensing planar structure (8) and the second sensing planar structure (80) are mutually oriented, that the winding formed by the transverse segments (6) and the connecting elements (5) of the first sensing planar structure (8) is oppositely oriented to the winding formed by the transverse segments (6) and the connecting elements (5) of the second sensing planar structure (80), wherein the series connection of the windings of the first sensing planar structure (8) and the second sensing planar structure (80) is formed by electrically conductively connecting the first end of the first sensing planar structure (8) with the first end of the second sensing planar structure (80) at the first end of the planar flexible core, wherein the second end of the winding of the first sensing planar structure (8) as well as the second end of the winding of the second sensing planar structure (80) is led out at the second end of the planar flexible core.
  9. The planar flexible non-invasive current sensor according to any one of the preceding claims, characterized in that it comprises a shielding planar structure (7) made of two layers of conductive material, the thickness of which is substantially less than the thickness of the planar flexible core, wherein the first layer of the shielding planar structure (7) is electrically isolated from the outside of the sensing planar structure (8, 80) on the first side away from the planar flexible core, and the second layer of the shielding planar structure (7) is electrically isolated from the outside of the sensing planar structure (8, 80) on the second side away from the planar flexible core.
  10. The planar flexible non-invasive current sensor according to claim 9, characterized in that the layers of the shielding planar structure (7) comprise a plurality of electrically interconnected transverse segments.
  11. The planar flexible non-invasive current sensor according to any one of claims 8 to 9, characterized in that each layer of the shielding planar structure (7) is formed by a continuous strip.
  12. The planar flexible non-invasive current sensor according to any one of the preceding claims, characterized in that , at the location of the connecting openable means (3), a compensating winding is electrically insulatingly wound around the planar flexible core and connected in series with the sensing planar structure (8, 80).

Description

Field of the invention The invention relates to the arrangement of the planar flexible non-invasive sensors for measuring alternating electric current. The invention falls within the field of electrical engineering. Background of the invention The flexible electric current sensors are based on a slender induction coil repeatedly shapeable so that it forms a closed path about the current conductor to be measured. The voltage induced into the coil is proportional to the derivative of the total current flowing through the closed area. This principle of measurement is also commonly known as the Rogowski principle or Rogowski coil according to the publication Rogowski W. and Steinhaus W., from 1912. The flexible electric current sensor consists of the sensing winding wound on the cylindrical flexible core, the possible electrical shield located above the mentioned sensing winding, and the outer insulating sheath. To convert the output voltage of sensor to the signal proportional to total current, the electronic integrator is usually used as part of the flexible sensor. Flexible sensors are advantageous for measuring current in large conductors, shaped conductors and conductor groups. Known designs of flexible current sensors have lower amplitude and phase accuracy compared to transformer-type sensors. The accuracy of flexible current sensors is affected by residual signals induced by inductive coupling to external sources of current signals and by the variable inductive coupling of the sensing coil to the conductor to be measured. Various arrangements of the Rogowski coil and associated electronics can be found in the references cited herein: Patent Application GB2259150A discloses the arrangement of electronic integrator with combined feedback, Patent Document US5442280 discloses the arrangement of fixed Rogowski coil as assembly on the printed circuit board, European Patent Application EP652441A1 discloses the arrangement of fixed Rogowski coil for installations with grounded metallic housing, Patent Document US6614218B1 discloses the arrangement of fixed Rogowski coil of electronic integrator with combined passive and active feedback, European patent application EP0834745A2 presents the arrangement of fixed Rogowski coil with high winding homogeneity, patent document JP2000065866 presents the arrangement of multiple Rogowski coils for measuring currents flowing through large structures, patent application GB2332784A presents the arrangement of flexible Rogowski coil wound on fixed support structure, patent application DE19811366A1 presents the arrangement of flexible Rogowski coil optimized for repetitive measurements on power conductors, patent application GB2342783A presents the arrangement of fixed Rogowski coil on the printed circuit board, patent application DE19959789A1 presents the arrangement of electronic integrator with switched feedback, patent document US6825650B1 presents the arrangement of multiple Rogowski coils for current measurements in electricity meters, patent document US6313623B1 presents the spatial arrangement of two Rogowski coils for elimination of residual signals, patent application US2003/0090356A1 presents the arrangement of fixed Rogowski coil on the printed circuit board with optical transmission line. Patent document US 7,847,543 B2 discloses the arrangement of sensing coil and electrical shielding structure improving accuracy and independence from external magnetic and electric fields. Patent document JP 6479370 B2 discloses a flexible current sensor that can easily wrap around various objects to measure electrical current, making it adaptable for different applications. It consists of a magnetic core covered with insulating layers and conductive stripes, allowing it to function effectively while maintaining flexibility. Patent document US 2020379017A1 discloses a closed loop current transducer designed to measure electrical currents with high precision by using a specialized sensing unit that detects magnetic fields. In the state of the art, the electric current sensor described in European patent application EP3566061A1 is also known. The sensor consists of sensing coil wound on cylindrical flexible core, wherein the mentioned sensing coil consists of two series-connected overlapping windings wound along the mentioned cylindrical flexible core in mutually opposite direction. The cylindrical flexible core consists of plurality of filaments of non-magnetic material arranged to the nearest approximation of circular cross-section, and the sensing coil is further provided with non-conductive separating layer disposed between its windings. The disadvantage of this sensor is the difficult manufacturing of the winding coils and the overall difficult assembly of the sensor. Principal linearity, the absence of saturation of the non-magnetic core as well as a large frequency range are inherent properties of flexible current sensors that call the demand for their further refinement and