Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
  • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
  • G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices

Definitions

• the present invention relates to a device and a method for current measurement and in particular to a device and a method for measuring the current through one or more conductors of an arrangement of a plurality of current conductors arranged in the immediate vicinity.
• FIG. 1 For potential-free current measurement, it is known to place two magnetic field-sensitive sensors on both sides of a current conductor. Such an arrangement is shown schematically in FIG. 1, where two magnetic field-sensitive sensors 2 and 4 are arranged on both sides of a current conductor 6. The magnetic field caused by a current flowing through the conductor 6 is measured by the magnetic field sensitive sensors 2 and 4. The current in the conductor is determined by forming the difference between the output signals of the two magnetic field-sensitive sensors 2 and 4, an existing, gradient-free magnetic field in the current measurement being able to be eliminated by this principle.
• a disadvantage of the arrangement described above is that 2n sensors are required if the current in n conductors is to be measured simultaneously.
• the present invention thus enables the required magnetic field-sensitive sensors to be reduced from 2n to n + 1 if the current is to be detected through n conductors.
• the present invention enables the compensation of influences, which are brought about by conductors arranged in the vicinity, through which current flows, on the current measurement in a conductor.
• the present invention provides a less expensive current measuring device, which on the other hand delivers exact results with current conductors arranged in the immediate vicinity.
• the present invention further provides a method for measuring the current through one or more conductors of an arrangement of n conductors, where n is a natural number ⁇ 2, in which first the output signals from n + 1 magnetic field-sensitive sensors, two of which are adjacent to one respective conductors are arranged, can be read out.
• the current through one or more of the conductors is subsequently calculated on the basis of the read-out output signals and coefficients which describe the influence of currents through each of the n conductors and a DC magnetic field on the output signal of each of the magnetic field-sensitive sensors.
• the magnetic field sensitive sensors are preferably Hall sensors. These Hall sensors are sensitive to vertical magnetic fields, so that the sensors are arranged between the conductors or in the conductor gap up or down.
• sensors can also be used according to the invention that are sensitive to magnetic fields that strike parallel to the surface, for example field plates. These sensors are arranged in such a relationship with the conductors that the magnetic field generated by the conductors strikes the sensors essentially parallel to the surface.
• FIG. 3 schematically shows an alternative arrangement of Hall sensors for current measurement according to the present invention
• Fig. 5 is a schematic representation of the current measuring device according to the invention.
• FIG. 2 shows schematically the arrangement according to the invention of magnetic field-sensitive sensors for measuring the current in three conductors L1, L2, L3 arranged in the immediate vicinity.
• only four magnetic field sensitive sensors S1, S2, S3 and S4 are required to measure the currents in the conductors L1, L2, L3.
• the four sensors are arranged such that two magnetic field-sensitive sensors, for example S1 and S2, are arranged adjacent to a respective conductor, for example L1.
• the output signals of all magnetic field sensitive sensors S1 to S4 linearly linked to one another via a matrix operation, the matrix coefficients being determined by means of a calibration measurement, in such a way that a defined current is passed alternately through each conductor, while the other conductors carry no current.
• a calibration measurement is carried out, in which the arrangement is subjected to a known DC magnetic field while no current flows through the conductors.
• the coefficients a ⁇ i to a ⁇ 4 are obtained while only a known current flows through the conductor L1, the coefficients a2 i to a24 are obtained while only a known current flows through the conductor L2, and the coefficients ate ⁇ to a34 are obtained while only a known current flows through the conductor L3.
• the coefficients a q ⁇ to a "4 are obtained while a known DC magnetic field is present and none of the conductors has a current flowing through it.
• the first number of the index of a respective coefficient denotes a conductor, while the second number in the index denotes a sensor, so that, for example, the coefficient aii describes the influence of a current through the conductor L1 on the output signal of the sensor S1.
• the coefficients a gl to a g the letter g stands for the constant magnetic field, so that these coefficients describe the influence of a constant magnetic field on the output signal of a respective sensor.
• a 2 a 21 a 22 a 23 a 24 ⁇ 12
• the individual currents I j to I flowing through the conductors L1 to L3 can thus be calculated as follows after an inversion of the coefficient matrix:
• the current can flow through everyone the current conductors L1 to L3 can be calculated exactly, only n-1 magnetic field-sensitive sensors being required if the current through n conductors is to be measured.
• the above-mentioned type of calculation also enables the detection of the DC magnetic field.
• FIG. 3 A schematic representation to illustrate an alternative arrangement of magnetic field-sensitive sensors with respect to three conductors in which a current is to be measured is shown in FIG. 3.
• four sensors S1 to S4 are arranged with respect to three conductors L1 to L3 in such a way that two magnetic field-sensitive sensors are arranged adjacent to a respective conductor.
• the sensors are each displaced vertically with respect to a line imagined by the conductors, for example displaced upwards or downwards with respect to the conductors.
• Such an arrangement can be easily implemented, for example, if the sensors are Hall sensors and are manufactured monolithically with the conductors on a semiconductor substrate.
• FIG. 4 An arrangement of sensors to conductors when the sensors are sensitive to magnetic fields incident parallel to the surface, as is the case, for example, with field plates, is shown in FIG. 4.
• the field lines of a magnetic field which is generated by currents through the conductors L1 to L3, run parallel to the main surfaces of the sensors S1 to S4.
• n + 1 magnetic field-sensitive sensors are required to measure the currents through n conductors.
• FIG. 5 A schematic overview representation of a current measuring device according to the invention is shown in FIG. 5. Again, the arrangement of the three conductors L1 to L3 and the four magnetic field sensitive sensors S1 to S4 can be seen.
• the magnetic field sensitive sensors S1 to S4 are each connected to an evaluation unit 10.
• the sensors S1 to S4 are more specifically connected to a readout device 12 of the evaluation unit.
• the above-described calculation of the current through the respective conductors L1 to L3 is carried out in the evaluation unit 10.
• the evaluation unit 10 preferably also has a calibration device 14, by means of which the coefficients described above are determined.
• the calibration device 14 is connected in a suitable manner to the respective conductors L1 to L3 in order to be able to effect a known current flow through them. This is shown in FIG. 5 by the schematically illustrated lines between the calibration unit 14 and the respective conductors L1 to L3.
• a device for generating a known DC magnetic field (not shown) is preferably provided in order to enable the coefficients a 1 to a g 4 to be determined.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
• Measurement Of Current Or Voltage (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)

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• 1999
  • 1999-03-11 DE DE19910801A patent/DE19910801B4/de not_active Expired - Fee Related
• 2000
  • 2000-01-17 JP JP2002522688A patent/JP3579040B2/ja not_active Expired - Fee Related
  • 2000-01-17 US US09/889,790 patent/US6583613B1/en not_active Expired - Lifetime
  • 2000-01-17 CA CA002357023A patent/CA2357023C/en not_active Expired - Fee Related
  • 2000-01-17 AT AT00902600T patent/ATE214482T1/de active
  • 2000-01-17 WO PCT/EP2000/000316 patent/WO2000054063A1/de not_active Ceased
  • 2000-01-17 ES ES00902600T patent/ES2171384T3/es not_active Expired - Lifetime
  • 2000-01-17 DK DK00902600T patent/DK1114325T3/da active
  • 2000-01-17 PT PT00902600T patent/PT1114325E/pt unknown
  • 2000-01-17 EP EP00902600A patent/EP1114325B1/de not_active Expired - Lifetime
  • 2000-01-17 DE DE50000122T patent/DE50000122D1/de not_active Expired - Lifetime

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