Induction Heating Inverter Control for Low-Noise Container Detection
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Solution Overview
Problem
Induction heating devices experience driving noise and inefficiency when detecting the presence of a container due to sudden changes in current supply, leading to user inconvenience and potential misinterpretation of device failure.
Innovation Solution
A controller in the induction heating apparatus adjusts the duty ratio and frequency of switching signals to minimize noise during container detection by gradually increasing and decreasing these parameters, using a current sensor to determine the presence of a container based on resonance current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If current is supplied to the working coil through an inverter circuit to detect container presence, then container detection capability is improved, but driving noise increases due to instant increase in peak-to-peak current value
Solution Approach 1:
The patent applies dynamics by making the duty ratio of the switching signal variable rather than fixed. The controller dynamically adjusts the duty ratio based on the detected container presence and heating requirements, allowing the system to optimize performance while minimizing noise during detection phase and maximizing heating efficiency during operation phase.
Solution Approach 2:
The patent implements periodic action through the switching signal that periodically switches the inverter circuit on and off. By controlling the duty ratio (the proportion of on-time within each period), the system can detect containers using low-duty-ratio periodic signals to minimize noise, then switch to higher duty ratios for efficient heating, thus resolving the contradiction between detection capability and noise generation.
2Duration of action of stationary object
If continuous current is supplied to the working coil without a container, then the induction heating apparatus operates continuously, but electric power is wasted and overheat occurs
Solution Approach 1:
The patent implements feedback by continuously monitoring the current through the inverter circuit and detecting container presence. Based on this feedback, the controller automatically adjusts the duty ratio or stops current supply when no container is detected, preventing energy waste and overheat while maintaining continuous operation capability when containers are present.
Solution Approach 2:
The system performs self-service by automatically detecting container presence and adjusting its own operation parameters without user intervention. The controller monitors system state and self-regulates current supply, enabling continuous operation when needed while automatically preventing energy waste and overheating when containers are absent.
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
Minimizes driving noise and improves user satisfaction by optimizing the detection process, ensuring efficient and quiet operation of the induction heating device.
Implementation Method 1
induction heating involves generating eddy current in a container made of metal with a magnetic field that is generated around a coil when high-frequency power having predetermined magnitude is supplied to the coil
Implementation Method 2
induction heating involves generating eddy current in a container made of metal with a magnetic field that is generated around a coil
Implementation Method 3
when high-frequency power having predetermined magnitude is supplied to the coil
Implementation Method 4
it can be determined whether a container is placed over a working coil, based on resonance current generated in the working coil
Data Source
AI summary
An induction heating apparatus according to one embodiment includes a working coil disposed in a position corresponding to a heating zone, an inverter circuit that includes a plurality of switching elements and supplies current to the working coil, a driving circuit that supplies a switching signal to each of the switching elements included in the inverter circuit, a current sensor that measures a resonance current value and a magnitude of resonance current flowing in the working coil, and a controller that supplies a control signal for adjusting a duty ratio and a frequency of the switching signal to the driving circuit, to drive the working coil.