Variable Opening Current Bus for Accurate Sensor Placement
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Solution Overview
Problem
Existing current sensors face challenges in accurately measuring currents over a wide range, particularly in applications like battery monitoring and solar or wind generator regulation, due to limitations in sensitivity and precision, especially when dealing with varying current levels.
Innovation Solution
A current bus design with a variable opening diameter and thickness, optimized for minimal magnetic field strength and non-linearity, allows for precise placement of a current sensor to enhance measurement accuracy by minimizing the skin effect and maximizing non-linearity, thereby improving current measurement across a broad range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current sensor is placed in a conductor with reduced cross-sectional area, then measurement precision is improved, but magnetic field strength increases causing non-linearity and skin effect
Solution Approach 1:
The current bus features a non-uniform cross-sectional area with a reduced section at the sensing location and enlarged sections at the ends. This local variation in geometry concentrates the magnetic field in a controlled manner at the sensing point while the enlarged end sections distribute the current to reduce overall magnetic field strength and skin effect, resolving the contradiction between measurement precision and harmful magnetic field effects.
2Measurement precision
If the conductor cross-sectional area is reduced at the sensing point, then measurement precision is improved, but current carrying capacity decreases
Solution Approach 1:
The current bus is divided into distinct functional sections: enlarged current-carrying end sections and a reduced cross-sectional sensing section. This segmentation allows the bus to simultaneously handle high current through the enlarged sections while providing a concentrated magnetic field at the sensing point for accurate measurement, thus resolving the contradiction between measurement precision and current carrying capacity.
3Measurement precision
If the opening diameter is minimized for sensor placement, then measurement precision is improved, but manufacturing difficulty increases
Solution Approach 1:
The current bus employs a non-uniform cross-sectional area with a reduced section at the sensing location. This geometric parameter variation creates a naturally formed sensing opening that accommodates the sensor while maintaining manufacturability through standard fabrication processes, resolving the contradiction between measurement precision and manufacturing ease.
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 high accuracy and robustness in current measurement, maintaining low magnetic field strength and minimizing temperature increase, while allowing for efficient current sensing across varying current levels, as demonstrated by 3-dimensional finite element simulations.
Implementation Method 1
A current bus 10 for carrying current with an opening 11 that extends from one side 12 of the current bus 10 to an opposing side of the current bus 10. The opening 11 changes in size as the opening 11 extends from one side 12 of the current bus 10 to the opposing side of the current bus 10.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A current bus (10) that includes an opening (11) that extends from one side of the current bus to an opposing side of the current bus. The opening changes in size as the opening extends from one side of the current bus to the opposing side of the current bus. The opening may include a first diameter and a second diameter that is different than the first diameter. The opening may include a first thickness at the first diameter of the opening which may be much smaller than a second thickness (T2) of the current bus. A high accuracy current measurement of the current bus may require that the magnetic field profile of the current bus within the opening be non-linear (e.g., 3rd order polynomial with the highest value of the 3rd degree coefficient).