Induction Cooker Current Variation Temperature Detection
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Solution Overview
Problem
Conventional induction heating cookers face challenges in accurately detecting temperature changes of targets regardless of their material, leading to potential damage from excessive input current and unreliable temperature sensing.
Innovation Solution
The induction heating cooker incorporates a heating coil, a drive circuit, load determining means, and a control unit that fixes the driving frequency while monitoring variations in input and coil currents to sense temperature changes, ensuring consistent power supply and preventing excessive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the driving frequency is changed to maintain constant input power for temperature detection, then temperature change can be detected, but the variation in control amount may be too small depending on target material causing detection failure
Solution Approach 1:
The patent changes the detection parameter from driving frequency variation to input current variation. By monitoring input current changes while maintaining constant driving frequency, the system achieves reliable temperature detection across different target materials without the limitation of insufficient frequency variation.
2Adaptability or versatility
If the driving frequency is not fixed when target material changes, then the system can adapt to different materials, but excessive input current may be provided causing inverter temperature rise and damage
Solution Approach 1:
The patent implements feedback control by continuously monitoring input current variations and using this information to detect temperature changes and adjust power delivery. This feedback mechanism prevents excessive current by adapting to actual target conditions rather than relying on pre-set frequency adjustments for different materials.
Solution Approach 2:
The patent replaces the mechanical/frequency-based adaptation system with an electrical current-based detection and control system. Instead of changing driving frequency to adapt to different materials, the system uses input current monitoring to detect target conditions and control power delivery, eliminating the risk of excessive current.
3Measurement precision
If input current is monitored to detect temperature changes, then temperature sensing is achieved, but the variation in control amount may be insufficient for accurate detection
Solution Approach 1:
The patent transitions from one-dimensional frequency-based control to a two-dimensional approach combining constant frequency with current magnitude monitoring. By fixing frequency and monitoring current variations, the system captures temperature information through current changes, providing sufficient detection signal without losing control information.
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 solution allows for reliable temperature sensing across different materials, suppressing input current increases and enhancing the cooker's reliability by accurately determining material-specific driving frequencies.
Implementation Method 1
a heating coil that induction-heats a target
Data Source
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AI summary
An inverter circuit 23 is driven in accordance with a result of determination by load determining means. While a driving frequency for the inverter circuit 23 is fixed, a variation in input current or coil current per predetermined time period is obtained. A change in temperature of a target 5 is detected based on the variation per predetermined time period.