Thermal Conductivity Sensor Circuit Configuration for Low Voltage Sensitivity

Solution Overview

Problem

Thermal conductivity sensors face challenges in achieving sufficient sensitivity at low supply voltages, which is crucial for reliable and accurate measurements in various applications, including the automotive and industrial sectors.

Innovation Solution

The thermal conductivity sensor operates in two distinct circuit configurations: a first configuration with higher power dissipation during the heating phase and a second configuration with lower power dissipation during the measurement phase, utilizing a Wheatstone bridge circuit with resistors connected in parallel during heating and in series during measurement, allowing for enhanced sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a low supply voltage is provided to the thermal conductivity sensor, then power consumption is reduced, but measurement sensitivity deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidmeasurement sensitivity

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The measurement circuit dynamically switches between two circuit configurations (first and second) depending on the operational phase. During the heating phase, the first configuration with higher power dissipation is used to rapidly heat the sensor element. During the measurement phase, the second configuration with lower power dissipation is used to maintain the heated state while enabling sensitive measurements. This dynamic adaptation allows the sensor to achieve high sensitivity at low supply voltages by concentrating power delivery only when needed for heating.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The sensor operates in periodic cycles alternating between a heating phase and a measurement phase. During the heating phase, the circuit configuration provides higher power dissipation to heat the sensor element. During the subsequent measurement phase, the configuration switches to lower power dissipation mode. This periodic switching enables the sensor to accumulate thermal energy efficiently and then utilize it for sensitive measurements, resolving the contradiction between power consumption and measurement sensitivity.

Inventive Principle:

Principle #19Periodic action

2Speed

If higher power dissipation is used during heating phase, then heating speed is improved, but power consumption increases

Engineering Contradiction:

Improveheating speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The first circuit configuration is specifically designed to provide high power dissipation during the heating phase to rapidly heat the sensor element to the required measurement temperature. This preliminary heating action prepares the sensor for subsequent measurements. By confining high power consumption only to this preliminary heating stage and not during the measurement phase, the overall average power consumption is kept low while achieving fast heating when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The measurement circuit dynamically switches between two circuit configurations (first and second) depending on the operational phase. During the heating phase, the first configuration with higher power dissipation is used to rapidly heat the sensor element. During the measurement phase, the second configuration with lower power dissipation is used to maintain the heated state while enabling sensitive measurements. This dynamic adaptation allows the sensor to achieve high sensitivity at low supply voltages by concentrating power delivery only when needed for heating.

Inventive Principle:

Principle #15Dynamics

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 increases measurement sensitivity by a factor of four, enabling reliable and accurate measurements even at low supply voltages, reducing power consumption, and contributing to energy savings and green technology solutions.

Implementation Method 1

The first circuit configuration is associated with a first power dissipation of the measurement circuit at a supply voltage. The first power dissipation is greater than the second power dissipation.

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

Thermal conductivity sensors and associated operating methods

Methodology Applied

Scientific EffectThermal conductivity: Conduction (thermal)

Data Source

PatentUS20240402107A1Thermal conductivity sensors and associated operating methods

Publication Date: 2024.12.05 INFINEON TECHNOLOGIES AG

AI summary

A thermal conductivity sensor includes a measurement circuit configured to operate in a first circuit configuration during a heating phase of the measurement circuit and in a second circuit configuration during a measurement phase of the measurement circuit. The first circuit configuration is associated with a first power dissipation of the measurement circuit at a supply voltage. The second circuit configuration is associated with a second power dissipation of the measurement circuit at the supply voltage. The first power dissipation is greater than the second power dissipation.