Shunt Thermocouple for Accurate Current and Temperature Measurement

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Solution Overview

Problem

Current shunts used for current measurement are prone to inaccuracies due to non-uniform current flow and temperature effects, leading to low accuracy, especially in high-precision applications.

Innovation Solution

A shunt design comprising multiple pieces connected by conductive channels for uniform current flow, combined with a thermocouple device for accurate temperature measurement, which adjusts current calculations and detects potential overheating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single piece U-shaped shunt is used, then the device complexity is reduced, but the measurement precision deteriorates due to non-uniform current flow at corners

Engineering Contradiction:
Improveshunt structureVSAvoidcurrent measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The shunt is divided into multiple separate pieces (first shunt piece, second shunt piece, third shunt piece) instead of using a single U-shaped piece. This segmentation allows each piece to be designed with optimized current flow paths, eliminating the non-uniform current distribution problems at corners that occur in single-piece U-shaped designs.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If temperature compensation is not implemented, then the device complexity is reduced, but the measurement precision deteriorates due to temperature-induced resistance changes

Engineering Contradiction:
Improvetemperature compensation systemVSAvoidcurrent measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

A temperature sensor is integrated into the shunt to continuously monitor temperature changes. The measured temperature is fed back to a processor that calculates the temperature-induced resistance change and compensates for it in the current measurement calculation, thereby maintaining measurement precision across varying temperature conditions.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If multiple pieces are used to achieve uniform current flow, then the measurement precision is improved, but the device complexity increases

Engineering Contradiction:
Improvecurrent measurement accuracyVSAvoidshunt structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple shunt pieces are electrically connected in series to form a complete current measurement path. The first shunt piece, second shunt piece, and third shunt piece are combined through electrical connections (welding or bonding) to create a functionally integrated multi-piece shunt that achieves uniform current flow while maintaining structural coherence.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If temperature monitoring is added, then the reliability is improved by detecting overheating conditions, but the device complexity increases

Engineering Contradiction:
Improveoverheating detectionVSAvoidtemperature monitoring system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The temperature sensor serves multiple functions: it monitors temperature for safety (detecting overheating conditions that could damage components), provides data for resistance compensation in current measurements, and can trigger protective actions. This multi-functionality justifies the added complexity by delivering multiple benefits from a single component.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution provides accurate and reliable current measurements by ensuring uniform current flow and compensating for temperature variations, while also detecting overheating conditions to prevent damage to components.

Implementation Method 1

a thermocouple device that includes a shared conductor for a shunt measurement and a thermocouple measurement

Methodology Applied
Scientific EffectThermocouple effect: Thermocouple

Implementation Method 2

The conductive channel may be a recess, raised portion, stand-alone component, or other channel that directs current to flow from one piece of the shunt to another piece in a uniform manner

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

temperature changes at the shunt affect the resistance of the shunt, which further decreases the accuracy of the current measurements

Methodology Applied
Scientific EffectTemperature-dependent resistance: Electrical Resistance

Data Source

PatentEP3559686B1Shunt thermocouple
Publication Date: 2022.05.11 ITRON INC
  • EP3559686B1 patent drawingFigure 1
  • EP3559686B1 patent drawingFigure 2A~2C
  • EP3559686B1 patent drawingFigure 3A~3B

AI summary

A thermocouple device includes a shared conductor for a shunt measurement and a thermocouple measurement. For example, the thermocouple device may include a shared conductor that provides a signal to both calculate current of a shunt and calculate a temperature of the shunt. The thermocouple device may provide an efficient structure that accurately calculates current and temperature. In addition, the thermocouple device may use the temperature of the shunt to detect when a conductive path is overheating. The temperature of the shunt may also be used for other purposes.