Compensation current sensor arrangement

Abstract

The current sensor arrangement according to the compensation principle has a primary conductor, designed to generate a primary magnetic field dependent on a current to be measured flowing through it, a first secondary winding, designed to generate a first secondary magnetic field dependent on a first compensation current flowing through said winding, a second secondary winding designed to generate a second secondary magnetic field dependent on a second compensation current flowing through said winding, a magnetic field sensor designed to generate a measurement signal that represents a magnetic field detected by it; a magnetic core of soft magnetic material designed and arranged to magnetically interconnect a primary conductor, a first seconding winding, a second secondary winding, and a magnetic field sensor; a first evaluation circuit; and a second evaluation circuit.

1 . A current sensor arrangement according to the compensation principle comprising: a primary conductor that is designed to generate a primary magnetic field dependent on a current to be measured flowing through it, a first secondary winding that is designed to generate a first secondary magnetic field dependent on a first compensation current flowing through it, a second secondary winding that is designed to generate a second secondary magnetic field dependent on a second compensation current flowing through it, a magnetic field sensor that is designed to generate a measurement signal that represents a magnetic field detected by it, a magnetic core of soft magnetic material that is designed and arranged to connect a primary conductor, a first secondary winding, a second secondary winding, and a magnetic field sensor to each other, a first evaluation circuit, downstream from the magnetic field sensor and upstream from the first secondary winding, that is designed to generate a first compensation current corresponding to the measurement signal of the magnetic field sensor and thus feed the first secondary winding, and a second evaluation circuit, upstream from the second winding, that is designed to generate a second compensation current corresponding to the first compensation current, and thereby feed the second secondary winding, wherein: the magnetic field detected by the magnetic field sensor is the magnetic field in the magnetic core resulting from the superposition of the primary magnetic field, a first secondary magnetic field, and the second secondary magnetic field, the first compensation current and the second compensation current are set by the first evaluation circuit and the second evaluation circuit in such a manner that the resulting magnetic field detected by the magnetic field sensor becomes zero, the second compensation current is greater or smaller than the first compensation current and the first or second compensation current represents the current to be measured flowing in the primary conductor. 
     
     
         2 . The current sensor arrangement according to  claim 1 , wherein the second evaluation circuit comprises a mechanism that evaluates the first compensation current and adjusts the second compensation current proportionally to the measured first compensation current. 
     
     
         3 . The current sensor arrangement according to  claim 2 , wherein the output signal, which represents the current to be measured flowing the in the primary conductor, is generated from the first or second compensation current. 
     
     
         4 . The current sensor arrangement according to  claim 2 , wherein the first compensation winding and second compensation winding have wires with wire diameters that are measured in such a manner that the current densities are identical in each when the first compensation current or the second compensation current flow through them respectively. 
     
     
         5 . The current sensor arrangement according to  claim 1 , wherein the first secondary winding and second secondary winding have different turn numbers. 
     
     
         6 . The current sensor arrangement according to  claim 1 , wherein the first evaluation circuit and the second evaluation circuit each have a driver circuit, which generates the first compensation current and the second compensation current in the first compensation winding and the second compensation winding respectively. 
     
     
         7 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits has an output-side half-bridge circuit. 
     
     
         8 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits has an output-side full-bridge circuit. 
     
     
         9 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits is a linear driver circuit. 
     
     
         10 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits is a pulse width-modulated driver circuit. 
     
     
         11 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits is a driver circuit supplied with bipolar supply voltages. 
     
     
         12 . The current sensor arrangement according to  claim 6 , wherein at least one of the driver circuits behaves on its output side like a current source. 
     
     
         13 . The current sensor arrangement according to  claim 1 , wherein the magnetic core is a round, enclosed, ring-shaped magnetic core with at least an air gap or a probe case. 
     
     
         14 . The current sensor arrangement according to  claim 1 , wherein the magnetic core is a rectangular or polygonal, enclosed, ring-shaped magnetic core with at least four arms and at least an air gap or a probe case. 
     
     
         15 . The current sensor arrangement according to  claim 14 , wherein the ampere-turns number is equal on each of the wrapped arms. 
     
     
         16 . The current sensor arrangement according to  claim 13 , wherein the first compensation winding and the second compensation winding are wrapped in symmetrically arranged sections. 
     
     
         17 . The current sensor arrangement according to  claim 13 , wherein the magnetic core is wrapped by the first compensation winding and the second compensation winding in an equally distributed manner over the entire magnetic core. 
     
     
         18 . The current sensor arrangement according to  claim 16 , wherein the first compensation winding and the second compensation winding are wrapped in each other. 
     
     
         19 . The current sensor arrangement according to  claim 16 , wherein the first compensation winding and the second compensation winding are wrapped over each other. 
     
     
         20 . The current sensor arrangement according to  claim 1 , wherein the second compensation current is at least 20 percent smaller than the first compensation current.