Induction Heating Element Impedance Temperature Control
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Solution Overview
Problem
Existing induction cooking devices face challenges in accurately determining the temperature of objects being heated without the need for additional temperature sensors, which can limit accuracy and increase costs.
Innovation Solution
An induction cooking appliance with a control unit that determines the temperature of an object by analyzing the impedance of the heating element and the object, using electrical parameters such as current, voltage, and power, and accounting for the frequency of the high-frequency alternating current supplied, thereby eliminating the need for separate temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature sensors are used to detect object temperature, then temperature measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses electrical impedance as an intermediary parameter to indirectly measure object temperature. Instead of directly measuring temperature with sensors, the system measures the electrical impedance of the heating element which changes with temperature, and uses this impedance data to determine the object temperature through calculation and lookup tables.
Solution Approach 2:
The patent replaces physical temperature sensors with an electrical measurement system. The control unit measures electrical parameters (voltage, current, impedance) and uses these electrical measurements to infer temperature, substituting the need for thermal sensing components.
2Measurement precision
If additional temperature sensors are installed, then temperature detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The heating element serves multiple functions: it heats the object and simultaneously acts as a temperature sensing element through its impedance characteristics. This multi-functionality eliminates the need for separate temperature sensors, reducing component count and manufacturing cost while maintaining temperature measurement capability.
Solution Approach 2:
The heating element itself provides the temperature information needed for control through its impedance changes. The system uses the inherent electrical properties of the heating element to self-monitor its thermal state, eliminating the need for external sensing components.
3Device complexity
If impedance-based temperature determination is used, then device complexity is reduced, but measurement precision may be affected by frequency variations
Solution Approach 1:
The system continuously measures electrical impedance and uses this feedback to determine temperature. The control unit monitors impedance changes in real-time and adjusts heating power accordingly, creating a closed-loop control system that compensates for variations and maintains measurement accuracy.
Solution Approach 2:
The patent accounts for frequency variations by using impedance measurements taken at the actual operating frequency rather than assuming a fixed frequency. The system adapts to frequency changes by measuring impedance at the current operating conditions and using frequency-compensated lookup tables or calculations to determine accurate temperature values.
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 method allows for precise temperature determination with high accuracy and reduced costs, providing improved operating convenience and performance by avoiding sensor limitations and fluctuations.
Implementation Method 1
generate an alternating electromagnetic field, particularly with a frequency between 17 kHz and 150 kHz, which is specifically intended to be converted into heat in a particularly metallic, preferably ferromagnetic, object to be heated by means of eddy current induction
Implementation Method 2
converted into heat in a particularly metallic, preferably ferromagnetic, object to be heated by means of eddy current induction and/or remagnetization effects
Implementation Method 3
the control unit is designed to determine the temperature of the object heated by the heating element from the impedance of a system comprising the heating element and the object
Data Source
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AI summary
The aim of the invention is to provide an appliance of the type in question having improved properties with respect to temperature determination. This aim is achieved, according to the invention, by a cooking appliance, in particular an induction cooking appliance, having at least one heating element (12), which is provided for heating at least one object (14) in at least one heating operation state, and having a control unit (16), which control unit is provided for determining a temperature (T) of the object (14) heated by the heating element (12) from an impedance (Z0) of a system (18) comprising the heating element (12) and the object (14) in the heating operation state.