Substrate-Embedded AC Current Sensors for Compact High-Bandwidth Sensing
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Solution Overview
Problem
Current transformer sensors are bulky due to a magnetic core, which is problematic for applications like printed circuit boards (PCBs), while coreless current sensors do not provide the bandwidth offered by current transformers.
Innovation Solution
AC current sensors with integrated coils in a substrate, utilizing twisted loops for differential sensing and rejecting stray magnetic fields, and an integrated circuit for measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If current transformer sensors are used, then bandwidth is improved, but size increases
Solution Approach 1:
The patent removes the magnetic core from the current transformer sensor, extracting only the essential sensing functionality. This eliminates the bulky magnetic core while maintaining the inductive sensing capability, thereby reducing sensor footprint while preserving bandwidth performance
Solution Approach 2:
The patent transitions from a three-dimensional magnetic core structure to a planar integrated coil structure on a substrate. This dimensional change allows the sensor to achieve transformer-like bandwidth performance in a two-dimensional footprint, solving the size-bandwidth contradiction
2Area of stationary object
If coreless current sensors are used, then size is reduced, but bandwidth decreases
Solution Approach 1:
The patent merges the current conductor, sensing coil, and signal conditioning circuitry into a single integrated sensor package. This integration allows coreless sensor compactness while incorporating transformer-like inductive sensing to maintain bandwidth performance
Solution Approach 2:
The integrated coil structure serves multiple functions: it acts as both the current conductor and the sensing element, and the substrate integrates both mechanical support and electrical signaling functions. This multi-functionality enables compact design without sacrificing bandwidth
3Object-affected harmful factors
If integrated coils are used, then stray magnetic field rejection is improved, but device complexity increases
Solution Approach 1:
The patent employs an asymmetric twisted loop coil configuration where the coil geometry is deliberately asymmetric with respect to the current conductor. This asymmetry creates differential sensing that rejects common-mode stray magnetic fields while maintaining sensitivity to the target current signal
Solution Approach 2:
The patent converts the potential harm of stray magnetic fields into a benefit by using differential sensing. The twisted loop configuration causes stray fields to induce equal and opposite voltages in the two loops, which cancel out, while the target current produces differential signals that add constructively
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides high bandwidth with a small footprint, being largely insensitive to stray magnetic fields.
Implementation Method 1
an integrated coil integrated in a substrate and configured for inductive coupling with the busbar
Implementation Method 2
the integrated coil includes a twisted loop, and where the integrated coil is configured to provide differential sensing of current in the busbar and to reject stray magnetic fields
Data Source
AI summary
AC current sensors are described having a primary current path that is integrated in a substrate or separate from the substrate; one or more conductive loops integrated in the substrate and configured for inductive coupling with the primary current path; and an integrated circuit connected to the conductive loop(s) and configured to measure AC current in the primary current path. The one or more integrated coils or loops can include one or more twisted loops configured to provide differential sensing of current in the primary current path and reject stray magnetic fields. In some embodiments, the one or more integrated coils or loops include one or more pairs of integrated coils or loops, with one coil or loop of each pair on each side of the main current path.