Thermally Symmetrical Bus Bar for Redundant Current Sensing
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Solution Overview
Problem
Current sensing technologies face challenges due to temperature-induced errors, particularly in high-precision measurements across a wide dynamic range, and there is a need for improved reliability, redundancy, and fault tolerance in complex electrical systems.
Innovation Solution
A thermally symmetrical bus bar design with strategically placed shunt resistors and magnetic portions to balance thermal flux, reducing offset voltage from the Seebeck effect, combined with redundant current sensing using voltage and magnetic field measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shunt resistors are used for current sensing, then voltage drop measurement provides current information, but temperature variations cause measurement errors
Solution Approach 1:
The patent applies the Seebeck effect (a harmful thermal phenomenon) beneficially by using thermocouples to measure temperature gradients at the shunt resistor. This converts the temperature-induced measurement errors into useful temperature data that can be compensated to improve current measurement accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where temperature measurements from thermocouples are used to calculate and compensate for temperature-induced errors in the shunt resistor measurements. This closed-loop approach continuously corrects measurement errors based on actual temperature conditions.
2Measurement precision
If magnetic sensors are used for current sensing, then non-contact measurement is achieved, but temperature variations still affect measurement accuracy
Solution Approach 1:
The patent uses the Seebeck effect to measure temperature gradients that affect magnetic sensors, converting the harmful thermal influence into useful compensation data. This allows correction of temperature-induced errors in magnetic field measurements.
Solution Approach 2:
Temperature measurements from thermocouples provide feedback to compensate for thermal effects on magnetic sensor readings, creating a closed-loop system that maintains accuracy across varying temperature conditions.
3Reliability
If redundant sensing is implemented, then reliability and fault tolerance improve, but system complexity increases
Solution Approach 1:
The patent combines multiple sensing modalities (shunt resistors, magnetic sensors, and thermocouples) into an integrated sensor system. This merging approach achieves redundancy and improved reliability while managing complexity through unified system architecture and shared signal processing.
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
Accurate and stable current measurement is achieved with reduced temperature sensitivity and enhanced reliability, enabling high-frequency and high-current sensing.
Implementation Method 1
One common approach to current sensing involves the use of shunt resistors, where the voltage drop across a known resistance is measured to determine the current flow
Implementation Method 2
Another popular technique is the use of magnetic sensors, such as Hall-effect sensors, which detect the magnetic field generated by the current flowing through a conductor
Implementation Method 3
the offset voltage due to the Seebeck effect at the junction of a shunt is reduced
Data Source
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AI summary
A bus bar is provided with a first and second terminals for a redundant current sensing system, which allows reading the voltage drop across a shunt resistor and a magnetic field over a portion of the bus bar. The elements that allow these measurements are provided along the bus bar including dummy elements for increasing the thermal symmetry of the bus bar, so as to reduce or remove the offset caused by the Seebeck effect due to the heating and thermal flux at the shunt resistor.