Current sensors

Abstract

Embodiments relate to magnetic field current sensors having sensor elements for sensing at least two magnetic field components, for example Bx and By. The current in a conductor is estimated by Bx and Bx/By, wherein Bx is the primary measurement and Bx/By is a corrective term used to account for position tolerances between the sensor and the conductor. In other embodiments, the corrective term can be dBx/By, where dBx is a difference in between components sensed at different sensor elements. The particular field components can vary in embodiments; for example, the current can be estimated by By and By/Bx, or dBy/Bx or some other arrangement.

What is claimed is: 
     
         1 . A current sensor for sensing current flow in a conductor comprising:
 a semiconductor die;   at least one magnetic field sensor element arranged on the semiconductor die and sensitive to a magnetic field in a first direction;   at least two magnetic field sensor elements arranged on the semiconductor die and each sensitive to a magnetic field in a second direction different from the first direction; and such that the current flow in the conductor can be estimated from the magnetic fields in the second direction and the magnetic field in the first direction.   
     
     
         2 . The current sensor of  claim 1 , wherein the current flow in the conductor can be estimated from the magnetic field in the second direction and a ratio of the magnetic field in the second direction and the magnetic field in the first direction. 
     
     
         3 . The current sensor of  claim 2 , wherein the ratio is a calibration term to account for position tolerances between the current sensor and the conductor. 
     
     
         4 . The current sensor of  claim 1 , comprising two magnetic field sensor elements sensitive to the magnetic field in the second direction. 
     
     
         5 . The current sensor of  claim 4 , wherein the at least one magnetic field sensor element sensitive to the magnetic field in the first direction is disposed between the two magnetic field sensor elements sensitive to the magnetic field in the second direction. 
     
     
         6 . The current sensor of  claim 5 , wherein the current flow in the conductor can be estimated from a difference in the magnetic fields at the two magnetic field sensor elements sensitive to the magnetic field in the second direction and a ratio of the difference to the magnetic field in the first direction. 
     
     
         7 . The current sensor of  claim 1 , wherein a symmetry center of the magnetic field sensor elements nominally corresponds with a symmetry center of the conductor. 
     
     
         8 . The current sensor of  claim 1 , wherein the second direction is a direction in which the magnetic field sensor elements are spaced apart from the conductor and the first direction is a direction in which the magnetic field sensor elements are spaced apart from one another. 
     
     
         9 . A method comprising:
 sensing a first magnetic field component of a magnetic field related to a current flow;   sensing a second magnetic field component different from the first magnetic field component of a magnetic field related to the current flow; and   estimating the current flow from the first magnetic field component and the second magnetic field component.   
     
     
         10 . The method of  claim 11 , further comprising:
 determining a ratio of the second magnetic field component to the first magnetic field component; and   estimating the current flow from the first magnetic field component and the ratio.   
     
     
         11 . The method of  claim 9 , further comprising providing a current sensor comprising at least one sensor element sensitive to the first magnetic field component and at least one sensor element sensitive to the second magnetic field component. 
     
     
         12 . The method of  claim 11 , further comprising arranging the sensor elements on a semiconductor die of the current sensor. 
     
     
         13 . The method of  claim 12 , further comprising arranging the current sensor relative to the conductor. 
     
     
         14 . The method of  claim 13 , wherein the ratio accounts for position tolerances between the current sensor and the conductor. 
     
     
         15 . The method of  claim 14 , further comprising providing a signal when a position tolerance limit is exceeded. 
     
     
         16 . The method of  claim 13 , further comprising:
 installing the current sensor and the conductor; and   determining the ratio before in-field operation.   
     
     
         17 . The method of  claim 16 , further comprising periodically re-determining the ratio. 
     
     
         18 . The method of  claim 11 , further comprising providing a current sensor comprising at least two sensor elements sensitive to the second magnetic field component. 
     
     
         19 . The method of  claim 18 , further comprising:
 determining a difference in magnetic field components sensed at the at least two sensor elements sensitive to the second magnetic field component;   determining a ratio of the difference to the first magnetic field component; and   estimating the current flow from the second magnetic field component and the ratio of the difference to the first magnetic field component.