Removal of higher order magnetic interference in magnetic field based current sensors

摘要

A system for measuring current includes a conductive trace comprising N substantially parallel straight sections having a substantially constant cross-section, N≥4. Adjacent substantially straight sections are spaced apart by a given distance and each pair of adjacent straight sections is connected by a respective loop of the current trace such that current in odd-numbered straight sections flows in a first direction and current in even-numbered straight sections flows in an opposite direction. The N magnetic field based current sensors are each positioned on a respective straight section of the conductive trace. The current is calculated based on; $$ \frac{\begin{array}{c}(S\left(1\right)-\left(\begin{array}{c}N-1\\ 1\end{array}\right)S\left(2\right)+\left(\begin{array}{c}N-1\\ 2\end{array}\right)S\left(3\right)-\dots -\\ \left(\begin{array}{c}N-1\\ N-3\end{array}\right)S\left(N-2\right)+\left(\begin{array}{c}N-1\\ N-2\end{array}\right)S\left(N-1\right)-S\left(N\right))\end{array}}{2^{\left(N-1\right)}};$$ $$ \left(\begin{array}{c}M\\ k\end{array}\right)=\frac{M!}{\left(M-k\right)!k!};$$where M=N−1, and S(i) is the measured signal read at magnetic field based current sensor i.