Heating Element Current Sensing for Sensorless Object Temperature Estimation
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Solution Overview
Problem
Existing temperature control methods for heating elements used to remove moisture from objects require separate temperature sensors, leading to low usability and potential changes in the object's physical or chemical properties due to inappropriate temperature settings.
Innovation Solution
A method and device that estimate the temperature of a heated object by supplying power to a heating element, obtaining momentary current values, determining the object's characteristics, and calculating a parameter based on these values to predict moisture states and thickness, allowing for open-loop control without a separate temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate temperature sensor is used to monitor and adjust temperature in real time, then temperature control accuracy is improved, but device complexity and usability are worsened due to additional components
Solution Approach 1:
The heating element itself serves as the sensing element by utilizing its own electrical resistance changes with temperature. The system monitors the heating element's resistance to detect temperature and moisture content, eliminating the need for separate temperature sensors. This self-service approach allows the heating element to both heat and sense, reducing device complexity while maintaining measurement capability
Solution Approach 2:
The heating element is given dual functionality: it serves both as the heating source and as the temperature/moisture sensing element. By measuring the electrical resistance of the heating element, the system can determine both temperature and moisture content of the treated material, making the heating element a multi-functional component that replaces what would traditionally require separate sensors
2Measurement precision
If a separate temperature sensor is used to monitor temperature, then temperature control accuracy is improved, but ease of operation is worsened due to additional installation and calibration requirements
Solution Approach 1:
The heating element automatically provides temperature and moisture information through its electrical resistance characteristics. The control system simply needs to measure the resistance of the existing heating element without requiring separate sensor installation, calibration, or maintenance, significantly improving ease of operation
Solution Approach 2:
The sensing function is extracted from separate temperature sensors and integrated into the heating element itself. By taking out the need for separate sensing components and embedding the sensing capability within the heating element's electrical properties, the system becomes easier to operate with fewer installation and maintenance steps
3Productivity
If inappropriate temperature is used to remove moisture, then productivity is improved by faster processing, but harmful effects worsen due to changes in physical or chemical properties of the object
Solution Approach 1:
The system continuously monitors the heating element's resistance, which changes with temperature and moisture content of the treated material. This feedback information is used by the control system to automatically adjust the heating power, ensuring temperature remains within the optimal range for moisture removal without causing harmful effects to the material's properties
Solution Approach 2:
The system dynamically adjusts the heating parameter (electrical power) based on real-time measurements of the heating element's resistance. By changing the power level according to the measured resistance values that reflect temperature and moisture conditions, the system maintains optimal processing conditions that maximize productivity while preventing harmful effects
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
Enables accurate temperature estimation and moisture state determination, reducing the need for separate temperature sensors and improving control accuracy while maintaining the object's properties.
Implementation Method 1
a heating element configured for contacting the object and for Joule heating
Data Source
AI summary
Provided are a method and device for supplying power to a heating element. A method of estimating a temperature of a heated object includes: supplying power to a heating element for a predetermined period of time, the heating element being configured for contacting an object and for joule heating; obtaining momentary current values corresponding to the power at two or more respective points of time from a plurality of points of time included in the predetermined period of time; determining a characteristic of the object using at least one of the momentary current values; and estimating a temperature of the object based on a parameter calculated based on the momentary current values and the characteristic.