Current Measurement Device Temperature Compensation

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Solution Overview

Problem

High-current applications require precise current measurement, but conventional shunt resistors face challenges due to temperature-dependent resistance, leading to costly solutions or inaccurate measurements with simple copper clips.

Innovation Solution

A current measurement device and method that includes a voltage measurement circuit and correction circuit to estimate and correct for temperature changes in a resistive element, using a temperature sensor to generate an output signal indicative of the current, thereby compensating for temperature-dependent resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a simple copper clip is used as a shunt resistor, then the cost is reduced, but the measurement precision deteriorates due to high temperature dependence of resistance

Engineering Contradiction:

ImprovecostVSAvoidmeasurement precision

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent changes the parameter being measured from direct voltage to temperature. By measuring the temperature of the shunt resistor (which changes with current flow) and using this temperature information to correct the resistance value, the system achieves precise current measurement with simple, inexpensive resistive elements that have high temperature coefficients.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by measuring the temperature of the shunt resistor and using this measurement to correct the current calculation. The temperature measurement feeds back into the system to compensate for the temperature-dependent resistance, allowing continuous correction and maintaining measurement precision under varying thermal conditions.

Inventive Principle:

Principle #23Feedback

2Measurement precision

If special temperature constant shunt resistors are used, then the measurement precision is improved, but the cost increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, specialized temperature-compensated shunt resistors with inexpensive, simple resistive elements (such as copper clips). The system accepts that these simple resistors will experience temperature changes but compensates through measurement and correction, achieving the same precision at much lower cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

Instead of trying to maintain constant resistance through special materials, the patent changes the approach by measuring the temperature parameter and using it to calculate and correct the resistance value, thereby achieving precision without requiring expensive temperature-stable materials.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If high currents flow through the shunt resistor, then the measurement capability is improved, but the temperature change increases causing measurement errors

Engineering Contradiction:

Improvemeasurement precisionVSAvoidtemperature change

Core Design Contradiction:

Measurement precisionVSTemperature

Solution Approach 1:

The patent uses feedback to continuously monitor the temperature of the shunt resistor during high-current operation. By measuring the temperature and using it to correct the resistance value in real-time, the system maintains measurement precision even when large temperature changes occur due to high current flow.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent converts the harmful effect of temperature change into a useful measurement parameter. The temperature change, which normally causes measurement errors, is measured and used as correction information to improve the accuracy of the current measurement, turning a problem into a solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach enables precise current measurement, even with temperature-dependent resistive elements, by dynamically correcting for rapid temperature changes, thus improving measurement accuracy and reducing costs compared to specialized shunt resistors.

Implementation Method 1

the current flowing through the shunt resistor may heat the shunt resistor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a temperature sensor to generate an output signal indicative of the current, thereby compensating for temperature-dependent resistance

Methodology Applied

Scientific EffectTemperature sensing:

Implementation Method 3

a high temperature dependence of the resistance and, therefore, of the voltage across the shunt resistor would result

Methodology Applied

Scientific EffectTemperature-dependent resistance: Thermo-resistive Effect

Data Source

PatentUS11137471B2Current measurement device, current measurement method and calibration method

Publication Date: 2021.10.05 INFINEON TECHNOLOGIES AG

AI summary

Current measurement device and methods are provided. An output signal is provided based on a voltage across a resistive element. A correction circuit is configured to estimate an indication of a temperature change of the resistive element based on the voltage across the resistive element and to correct the output of the current measurement device based on the indication of the temperature change and a measured temperature.