US 12,480,978 B2
Current measuring apparatus with redundant current measurement
Jan Marien, Herborn (DE); and Benedikt Kramm, Wettenberg (DE)
Assigned to ISABELLENHÜTTE HEUSLER GMBH & CO. KG., Dillenburg (DE)
Appl. No. 18/005,345
Filed by Isabellenhütte Heusler GmbH & Co. KG, Dillenburg (DE)
PCT Filed Apr. 20, 2021, PCT No. PCT/EP2021/060245
§ 371(c)(1), (2) Date Jan. 12, 2023,
PCT Pub. No. WO2022/012791, PCT Pub. Date Jan. 20, 2022.
Claims priority of application No. 10 2020 118 637.1 (DE), filed on Jul. 15, 2020.
Prior Publication US 2023/0266368 A1, Aug. 24, 2023
Int. Cl. G01R 15/20 (2006.01); G01R 1/20 (2006.01)
CPC G01R 15/207 (2013.01) [G01R 1/203 (2013.01)] 21 Claims
OG exemplary drawing
 
1. A current measuring apparatus for measuring an electric current, comprising:
a) a low-resistance current measuring resistor for current measurement according to the four-wire technique, and
b) a magnetic field sensor, in particular as a Hall sensor or as a magnetoresistive magnetic field sensor, for redundant current measurement,
c) wherein the electric current to be measured is divided in the current measuring apparatus into a main current path with a main current and a secondary current path with a secondary current, the main current path and the secondary current path together forming a parallel circuit,
d) wherein the low-resistance current measuring resistor is arranged in the main current path and has the main current flowing through it, and
e) wherein the magnetic field sensor is arranged in the secondary current path and measures the secondary current,
f) wherein the parallel circuit is designed such that the main current through the main current path with the low-resistance current measuring resistor is greater than the secondary current in the secondary current path with the magnetic field sensor, namely by a factor of at least 10,
g) wherein the low-resistance current measuring resistor is plate-shaped, with plate-shaped current connecting parts and a plate-shaped resistor element, the plate-shaped resistor element being arranged between the two plate-shaped current connecting parts in the direction of current flow,
h) wherein
a) a printed circuit board is arranged on the plate-shaped current measuring resistor, and
b) the printed circuit board makes contact with the two current connecting parts of the low-resistance current measuring resistor by means of in each case at least one through-plating, and
c) the magnetic field sensor is arranged on the printed circuit board, and
d) the magnetic field sensor on the one hand and the current measuring resistor on the other hand are arranged on opposite sides of the printed circuit board, and
e) a compensating resistor is arranged on the printed circuit board, and
f) the secondary current path runs on and/or in the printed circuit board, while the main current path runs through the low-resistance current measuring resistor, and
g) an evaluation circuit is arranged on the printed circuit board, which detects at least one of the following:
g1) the voltage drop across the resistance element of the low-resistance current measuring resistor,
g2) the output signal of the magnetic field sensor, and
g3) the voltage drop across the compensating resistor in the secondary current path,
and
h) the evaluation circuit has an interface for outputting the output signal of the magnetic field sensor.