Multi-Branch Bus Bar Layout for Low-Loss Current Sensing
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Solution Overview
Problem
Conventional bus bars with notches for current sensing suffer from increased resistance, heat loss, compromised AC performance, and decreased mechanical robustness, especially when notches are deep or result in thermal effects.
Innovation Solution
A bus bar design with a through-hole and notches forming branches, where a current sensor is positioned above one branch and adjacent to another, utilizing differential magnetic field sensing elements to measure current while minimizing stray field interference and maintaining mechanical and thermal robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If notches are added to the bus bar for current sensing, then current measurement capability is improved, but resistance increases and AC performance deteriorates
Solution Approach 1:
The patent transitions from planar notches to a three-dimensional through-hole structure. The through-hole penetrates the bus bar thickness dimension, creating multiple branches (first and second branches) that provide current sensing capability without compromising the horizontal current path. This dimensional change allows the sensing function to be achieved while maintaining low resistance and good AC performance.
Solution Approach 2:
The bus bar is segmented into multiple conductive layers embedded in the PCB, with the through-hole creating distinct first and second branches. The current sensor is positioned to measure only the first branch, separating the sensing function from the main current path. This segmentation allows independent optimization of sensing accuracy and current carrying capacity.
2Measurement precision
If deep notches are created for sensor placement, then current sensing is enabled, but mechanical robustness decreases
Solution Approach 1:
Instead of creating deep notches that compromise mechanical strength, the patent uses a through-hole that passes completely through the bus bar thickness. This creates a robust structure where the conductor maintains its integrity while providing defined branches for sensing. The through-hole approach preserves mechanical robustness better than deep notches while achieving the same sensing objective.
3Ease of operation
If the current sensor is positioned above the through-hole, then sensing is simplified, but stray field interference increases
Solution Approach 1:
The current sensor is positioned to measure only the first branch of the conductor, separated from the second branch by the through-hole structure. This spatial segmentation allows the sensor to detect current in the first branch while the second branch's current creates minimal interference. The notches and through-hole geometry are designed to direct magnetic field lines, reducing stray field coupling between branches.
Solution Approach 2:
The magnetic field sensing elements are strategically positioned to have maximum sensitivity to the first branch's magnetic field while minimum sensitivity to the second branch. The local geometry of the through-hole and notches creates a magnetic field distribution where the first branch's field is concentrated near the sensor, while the second branch's field is directed away, reducing interference.
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
The design achieves lower resistance and improved AC performance with enhanced mechanical and thermal robustness, while maintaining effective current measurement capabilities across varying frequencies.
Implementation Method 1
a current sensor that is disposed directly above the first branch of the conductor and to the side of the second branch of the conductor... the current sensor includes a first magnetic field sensing element and a second magnetic field sensing element
Data Source
AI summary
A system comprising: a conductor having a through-hole and a first notch that are formed therein, the through-hole and the first notch being arranged to define, at least in part, a first branch of the conductor, and the through-hole also being arranged to define, at least in part, a second branch of the conductor; and a current sensor that is disposed directly above the first branch of the conductor and the side of the second branch of the conductor, such that no portion of the current sensor is situated directly above the second branch.