Sensing apparatus for sensing current through a conductor and methods therefor

Abstract

A sensing apparatus for characterizing current flow through a conductor includes a plurality of magnetic sensors. In some embodiments, the sensors are grouped in pairs to achieve common mode rejection of signals generated in response to magnetic fields not resulting from current flow through the conductor. Sensors having different levels of sensitivity are used to collect information regarding the magnetic field generated by the current flowing through the conductor, where such information is processed in order to characterize the magnetic field. In some cases the sensors are included on or in flexible material that can be wrapped around the conductor.

What is claimed is: 
     
         1 . A sensing apparatus for sensing current through a conductor, the sensing apparatus comprising:
 a first pair of magnetic sensors, wherein each magnetic sensor of the first pair of magnetic sensors has a first level of sensitivity with respect to a magnetic field generated by the current through the conductor; and   a second pair of magnetic sensors, wherein each magnetic sensor of the second pair of magnetic sensors has a second level of sensitivity with respect to the magnetic field generated by the current through the conductor, wherein the second level of sensitivity is less than the first level of sensitivity.   
     
     
         2 . The sensing apparatus of  claim 1 , wherein the sensing apparatus is disposed on a common substrate with the conductor. 
     
     
         3 . The apparatus of  claim 1 , wherein:
 each magnetic sensor of the first pair of magnetic sensors is positioned a first distance from a spatial axis corresponding to the conductor, wherein the spatial axis corresponds to a direction of current flow within the conductor; and   each magnetic sensor of the second pair of magnetic sensors is positioned a second distance from the spatial axis for the conductor, wherein the second distance is greater than the first distance.   
     
     
         4 . The apparatus of  claim 3 , further comprising a third pair of magnetic sensors, wherein each magnetic sensor of the third pair of magnetic sensors is positioned a third distance from the spatial axis for the conductor, wherein the third distance is greater than the second distance and a third level of sensitivity of magnetic sensors in the third pair of magnetic sensors is less than the second level of sensitivity. 
     
     
         5 . The apparatus of  claim 3 , wherein the first pair of magnetic sensors includes:
 a first magnetic sensor positioned at a first point on a first virtual circle having a radius equal to the first distance, wherein a center of the first virtual circle corresponds to the spatial axis for the conductor; and   a second magnetic sensor positioned at a second point on the first virtual circle.   
     
     
         6 . The apparatus of  claim 5 , wherein the first and second points are about 180 degrees apart on the first virtual circle. 
     
     
         7 . The apparatus of  claim 5 , wherein the second pair of magnetic sensors includes:
 a third magnetic sensor positioned at a first point on a second virtual circle having a radius equal to the second distance, wherein a center of the second virtual circle corresponds to the spatial axis for the conductor; and   a fourth magnetic sensor positioned at a second point on the second virtual circle.   
     
     
         8 . The apparatus of  claim 7 , wherein the first virtual circle and the second virtual circle are concentric virtual circles lying in a common plane perpendicular to the spatial axis for the conductor. 
     
     
         9 . The apparatus of  claim 7 , wherein the center of the first virtual circle is positioned at a different point on the spatial axis for the conductor than the center of the second virtual circle. 
     
     
         10 . The apparatus of  claim 1 , wherein each magnetic sensor of the first pair of magnetic sensors has a different composition than each magnetic sensor of the second pair of sensors. 
     
     
         11 . The apparatus of  claim 1 , wherein each magnetic sensor of the first pair of magnetic sensors has a same composition as each magnetic sensor of the second pair of sensors, and wherein the sensing apparatus further comprises buffering material positioned with respect to the second pair of magnetic sensors such that the buffering material reduces sensitivity of each of the magnetic sensors in the second pair of magnetic sensors such that each magnetic sensor of the second pair of magnetic sensors has the second level of sensitivity. 
     
     
         12 . The apparatus of  claim 1 , wherein each magnetic sensor in the first pair of magnetic sensors and the second pair of magnetic sensors senses magnetic field in a first direction, wherein the first direction is perpendicular to the spatial axis corresponding to the conductor. 
     
     
         13 . The apparatus of  claim 12 , wherein each magnetic sensor in the first pair of magnetic sensors and the second pair of magnetic sensors also senses magnetic field in a second direction, wherein the second direction is i) perpendicular to the spatial axis corresponding to the conductor and ii) perpendicular to the first direction. 
     
     
         14 . The apparatus of  claim 1 , wherein each magnetic sensor of the first pair of magnetic sensors has a first angular orientation with respect to a spatial axis corresponding to the conductor, wherein the spatial axis corresponds to a direction of current flow within the conductor, and wherein each magnetic sensor of the second pair of magnetic sensors has a second angular orientation with respect to the spatial axis corresponding to the conductor. 
     
     
         15 . The apparatus of  claim 1  further comprising:
 a plurality of additional pairs of magnetic sensors, wherein, within each pair of additional magnetic sensors, a first magnetic sensor of the pair has a sensitivity with respect to the magnetic field generated by the current through the conductor that is about equal to a sensitivity of a second magnetic sensor of the pair. 
 
     
     
         16 . The apparatus of  claim 15 , wherein at least one of the plurality of additional pairs of magnetic sensors includes magnetic sensors having the first level of sensitivity with respect to the magnetic field generated by the current through the conductor. 
     
     
         17 . A sensing apparatus for sensing current, the sensing apparatus comprising:
 a first pair of magnetic sensors, wherein each magnetic sensor of the first pair of magnetic sensors is positioned a first radial distance from a spatial axis corresponding to a conductor, wherein the spatial axis corresponds to a direction of current flow within the conductor;   a second pair of magnetic sensors, wherein each magnetic sensor of the second pair of magnetic sensors is positioned a second radial distance from the spatial axis corresponding to the conductor, wherein the second radial distance is greater than the first radial distance;   a third pair of magnetic sensors, wherein each magnetic sensor of the third pair of magnetic sensors is positioned a third radial distance from the spatial axis corresponding to the conductor, wherein the third radial distance is greater than the second radial distance; and   processing circuitry coupled to the first, second, and third pairs of magnetic sensors, wherein the processing circuitry is configured to select information received from at least one of the first, second, and third pairs of magnetic sensors as representative information regarding the current flow within the conductor.   
     
     
         18 . The sensing apparatus of  claim 17 , wherein the processing circuitry is further configured to:
 select the representative information such that it includes information received from a plurality of pairs of magnetic sensors; and   process the representative information to determine a magnitude of current flow within the conductor.   
     
     
         19 . A sensing apparatus for sensing current, the sensing apparatus comprising:
 a first pair of magnetic sensors, wherein each magnetic sensor of the first pair of magnetic sensors is positioned a first radial distance from a spatial axis corresponding to a conductor, wherein the spatial axis corresponds to a direction of current flow within the conductor;   a second pair of magnetic sensors, wherein each magnetic sensor of the second pair of magnetic sensors is positioned the first radial distance from the spatial axis corresponding to the conductor;   processing circuitry coupled to the first and second pairs of magnetic sensors, wherein the processing circuitry is configured to process information received from the first and second pairs of magnetic sensors to determine a magnitude of current flow within the conductor.   
     
     
         20 . The sensing apparatus of  claim 19 , wherein the processing circuitry is disposed on a common substrate with the first and second pairs of magnetic sensors.