Heating Temperature Measurement Circuit for Cooking Apparatus
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Solution Overview
Problem
Existing temperature detection methods for metal objects, such as in cooking apparatuses, suffer from inaccuracies due to thermistor placement issues and insufficient sensitivity to local temperature jumps, leading to unreliable temperature measurements.
Innovation Solution
A heating and temperature-measuring circuit that adjusts heating power and timing to optimize temperature measurement intervals based on operating modes, including standby, calibration, high-power, low-power, and power regulation heating, using pulse width modulation to improve accuracy by reducing heating power before measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If temperature measurement is performed during high-power heating, then heating efficiency is maintained, but temperature measurement accuracy deteriorates due to specific heat capacity effects and local temperature variations
Solution Approach 1:
The patent implements periodic switching between high-power heating mode and low-power measurement mode. During measurement periods, the heating power is reduced to a first power value, allowing accurate temperature detection. During heating periods, the power is increased to a second power value for efficient heating. This periodic alternation resolves the contradiction by separating the conflicting requirements of high-power heating and accurate measurement in time.
Solution Approach 2:
The patent performs preliminary low-power heating before temperature measurement to stabilize the temperature field and reduce local temperature variations. This preliminary action ensures that when measurement is taken, the specific heat capacity effects and local temperature jumps are minimized, thereby improving measurement accuracy without significantly compromising overall heating efficiency.
2Difficulty of detecting and measuring
If thermistor is placed close to metal object, then temperature detection sensitivity improves, but measurement accuracy deteriorates due to local temperature jump interference
Solution Approach 1:
The patent changes the power parameter during measurement to a low first power value, which reduces the magnitude of local temperature jumps and specific heat capacity effects. This parameter change allows the thermistor to maintain high sensitivity to temperature changes while avoiding the adverse effects of excessive local heating, thereby resolving the contradiction between sensitivity and accuracy.
Solution Approach 2:
The patent introduces an intermediary measurement mode with intermediate power level between high-power heating and zero-power measurement. This intermediary state allows the system to maintain adequate heating while minimizing local temperature variations, enabling the thermistor to accurately detect temperature without being overwhelmed by local temperature jumps.
3Measurement precision
If DC measurement power supply output capacity is increased, then temperature measurement accuracy improves, but system complexity increases
Solution Approach 1:
The patent makes the heating power supply circuit perform dual functions: it serves as both the high-power heating source and the low-power measurement power supply. By reusing the existing power supply infrastructure for both heating and measurement purposes, the system achieves accurate temperature measurement without requiring a separate high-capacity DC measurement power supply, thereby avoiding increased system complexity.
Solution Approach 2:
The heating power supply circuit serves itself by providing both heating and measurement functions. During measurement periods, the same power supply circuit that performs heating switches to a low-power output mode to enable accurate temperature detection, eliminating the need for external measurement power supply equipment and reducing overall system complexity.
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
Enhances temperature measurement accuracy by minimizing the impact of specific heat capacity and local temperature variations, ensuring precise temperature readings across different heating modes.
Implementation Method 1
a heating and temperature-measuring circuit is configured to heat a metal object via a heating coil by inputting an alternating-current voltage to the heating coil
Implementation Method 2
An existing method is to detect the temperature of the metal object with a thermistor
Data Source
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AI summary
A heating and temperature-measuring circuit (140) and a temperature measurement method therefor, and a cooking apparatus and a storage medium (150). In the heating and temperature-measuring circuit (140), an alternating-current voltage is input into a heating coil (12), such that the heating coil (12) heats a metal object (20), and the heating process comprises a plurality of "heating periods. The method comprises: determining an operating mode of a heating device (81); and according to the operating mode, determining a temperature measurement interval to perform temperature measurement, so as to make the heating power of a heating period before the temperature measurement interval less than a set power value (82). By means of the heating and temperature-measuring circuit (140) and the temperature measurement method therefor, the accuracy of temperature detection can be improved.