Heating Element Power-Rate Estimation for Sensorless Food Temperature Control
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Solution Overview
Problem
Existing kitchen appliances with heating elements face challenges in accurately controlling the temperature of food without the need for additional temperature sensors, leading to increased cost and complexity.
Innovation Solution
A method and apparatus that estimate the temperature of a material being heated by calculating the rate of change in electrical power supplied to the heating element, using a moving-average filter and a lookup table to determine thermal properties, allowing for temperature estimation without direct temperature sensing of the food.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an additional temperature sensor is added to directly measure the temperature of the foodstuff, then the temperature measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses the heating element as an intermediary to indirectly measure the food temperature. Instead of placing a sensor directly in the food, the system measures the power consumption of the heating element, which correlates with the food temperature through thermal transfer relationships. This intermediary approach avoids direct food contact sensors while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical/physical temperature sensor system with an electrical measurement system. By monitoring the electrical power consumption of the heating element and using thermal models to calculate temperature, the system substitutes direct thermal sensing with electrical measurement and computational estimation, reducing hardware complexity.
2Loss of information
If an additional temperature sensor and wireless connection are added to monitor food temperature, then the temperature monitoring capability is improved, but the device complexity increases
Solution Approach 1:
The heating element serves multiple functions: it heats the food and simultaneously acts as a temperature sensing element through its power consumption characteristics. This multi-functionality eliminates the need for separate temperature sensing hardware, reducing system complexity while maintaining temperature information capability.
Solution Approach 2:
The system uses its own heating element's electrical characteristics to provide temperature information about the food. The heating element essentially 'self-reports' temperature data through its power consumption pattern, eliminating the need for external sensing components and their associated communication infrastructure.
3Manufacturing precision
If the power supply to the heating element is controlled to maintain temperature within a predetermined range, then the temperature control precision is improved, but the device complexity increases
Solution Approach 1:
The system implements a feedback control mechanism where the measured power consumption of the heating element is continuously monitored and used to adjust the heating power. This feedback loop maintains temperature within the desired range by dynamically adjusting power supply based on real-time thermal conditions, achieving precise control through software-based regulation.
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 accurate temperature control of food without additional sensors, reducing system complexity and cost while maintaining the temperature within a predetermined range, effectively addressing the limitations of conventional systems.
Implementation Method 1
supplying electrical power to a heating element in dependence on a measured temperature
Implementation Method 2
calculating a rate at which the amount of electrical power supplied changes over time, comparing the calculated rate with a plurality of known values in order to determine the value of a parameter relating to thermal properties of the material being heated
Data Source
AI summary
A method of estimating a temperature of a material being heated is described. The method may comprise supplying electrical power to a heating element in dependence on a measured temperature, calculating a rate at which the amount of electrical power supplied changes over time, comparing the calculated rate with a plurality of known values in order to determine the value of a parameter relating to thermal properties of the material being heated, and calculating an estimated temperature based on the determined value of said parameter. In some embodiments, the method may further comprise detecting a drop in temperature of the material being heated, by detecting a change in the calculated rate at which the amount of electrical power supplied changes over time.