Current Sensor Using Temperature Difference Measurement

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Solution Overview

Problem

Current current-sense modules are expensive and not suitable for applications requiring less precise measurement, as they react too quickly to current changes, making them costly for industrial uses where slower responses are needed, and they fail to account for temperature differences between the resistance element and connection parts.

Innovation Solution

A current sensor that measures the temperature difference between the resistance element and connection parts using thermoelements, generating a thermoelectric voltage to derive the current, with a thermopile arrangement that allows for low heat transfer resistance and optional redundant measurement via four-wire voltage measurement, enabling slower response times and cost-effective production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a current-sense module with ASIC is used, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvecurrent measurement precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive ASIC-based current sense modules with a simple temperature difference measurement system using inexpensive thermoelements. The core idea is to use the temperature difference between the resistance element and connection parts as a proxy for current measurement, eliminating the need for complex and costly ASIC integrated circuits while achieving sufficient measurement capability for industrial applications.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the electronic measurement system (ASIC-based voltage measurement) with a thermal measurement system (temperature difference measurement using thermoelements). By measuring the temperature difference caused by Joule heating in the resistance element, the system replaces complex electronic circuitry with a simpler thermal measurement approach that is cheaper to manufacture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a current-sense module with ASIC is used, then measurement precision is improved, but response speed to current changes increases

Engineering Contradiction:

Improvecurrent measurement precisionVSAvoidresponse speed to current changes

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent changes the measurement parameter from instantaneous voltage drop to temperature difference. Since temperature changes slowly compared to voltage changes, this parameter transformation inherently slows down the response time. The temperature difference measurement integrates the thermal mass and heat capacity effects, causing the system to respond more slowly to current changes, which is desirable for avoiding false triggering from short-term peaks.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If temperature difference between resistance element and connection parts is not measured, then device complexity is reduced, but measurement accuracy deteriorates due to temperature-dependent errors

Engineering Contradiction:

Improvemeasurement system complexityVSAvoidcurrent measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent uses the temperature difference itself as the measurement signal. Instead of trying to compensate for temperature effects separately, the system directly measures the temperature difference caused by Joule heating as the primary indicator of current. This self-service approach eliminates the need for separate temperature compensation circuits while actually improving measurement accuracy by directly accounting for thermal effects.

Inventive Principle:

Principle #25Self-service

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 a cost-effective current measurement system with a slower response to current changes, reducing false triggering from short-term peaks and accounting for temperature differences, suitable for industrial applications, while maintaining precision through redundant measurement principles.

Implementation Method 1

The thermoelement generates a thermoelectric voltage in an energized condition of the current sensor according to the Seebeck Effect

Methodology Applied

Scientific EffectSeebeck Effect: Seebeck Effect

Implementation Method 2

an appropriately larger thermal power loss occurs in the resistance element generating heat

Methodology Applied

Scientific EffectJoule Heating: Joule Heating

Data Source

PatentUS9435832B2Electronic component, in particular current sensor

Publication Date: 2016.09.06 ISABELLENHUTTE HEUSLER GMBH & CO KG

AI summary

The invention relates to an electronic component (1), in particular a current sensor, having a resistance element (5) made of a resistance material, a first connection part (3) made of a conductor material for introducing an electrical current into the resistance element (5), and a second connection part (4) made of a conductor material for discharging the electrical current from the resistance element (5). According to the invention, the component (1) has a temperature-measuring device (8) for measuring a temperature difference between the resistance element (5), on the one hand, and at least one of the two connection parts (3, 4), on the other hand, in order to derive the current from the temperature difference.