Induction Heating Resonance Tracking Using Inverter Current Feedback
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Solution Overview
Problem
Induction heating devices face efficiency issues when the resonance frequency changes due to movement of the object being heated, as the driving frequency of the inverter deviates from the resonance frequency, leading to decreased efficiency.
Innovation Solution
A heating device with a parallel resonance circuit, an inverter unit, a current sensor, and a controller that adjusts the driving frequency to track the resonance frequency, ensuring the peak value of the output current remains below a predetermined threshold, even when the object's position changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the driving frequency of the inverter is kept constant during heating operation, then the control system is simple, but the heating efficiency decreases when the resonance frequency changes due to object movement
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the output current from the inverter and adjusts the driving frequency based on the detected current characteristics. When the object moves and resonance frequency changes, the feedback loop detects the deviation through current measurement and automatically retunes the inverter frequency to maintain resonance, thereby preserving heating efficiency without requiring complex manual intervention
Solution Approach 2:
The patent transitions from a static frequency control approach to a dynamic frequency tracking approach. The inverter's driving frequency is no longer fixed but dynamically adjusted in real-time to follow the changing resonance frequency of the heating system. This dynamic adaptation allows the system to maintain optimal operating conditions despite object movement, resolving the contradiction between control simplicity and heating efficiency
2Loss of energy
If the driving frequency tracks the resonance frequency dynamically, then the heating efficiency is maintained, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent enables the heating system to self-adjust its operating frequency automatically. The controller uses the output current signal from the inverter itself as the basis for frequency adjustment, without requiring external sensors or complex measurement systems. The system monitors its own operational parameters and autonomously retunes to maintain resonance, reducing the need for additional complex components while preserving heating efficiency
Solution Approach 2:
The patent focuses on dynamically changing the frequency parameter of the inverter output based on real-time system conditions. By continuously adjusting this single critical parameter (driving frequency) according to the resonance characteristics detected through current measurement, the system maintains optimal performance without requiring comprehensive changes to the entire control architecture, thus limiting the increase in device complexity
3Device complexity
If the inverter operates at fixed frequency, then the device structure is simple, but the inverter current increases when deviating from resonance frequency
Solution Approach 1:
The patent employs feedback control where the controller monitors the output current magnitude and uses this information to adjust the inverter frequency. When object movement causes resonance frequency shift, the feedback mechanism detects the resulting current increase and automatically retunes the frequency to restore resonance conditions, thereby reducing inverter current back to optimal levels without requiring structural complexity
Solution Approach 2:
The patent introduces dynamic frequency adjustment capability that allows the inverter to adapt its operating frequency in real-time. This dynamic behavior enables the system to track the moving resonance frequency peak, ensuring operation at maximum efficiency points regardless of object position changes, thus preventing excessive inverter current draw while maintaining relatively simple device structure through software-based control
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 the heating device to maintain efficiency by automatically tracking the resonance frequency, reducing inverter current and ensuring optimal heating performance despite changes in the object's position.
Implementation Method 1
a parallel resonance circuit including an inductor including the heating coil and a resonance capacitor resonating with the inductor
Implementation Method 2
a heating coil for heating a cooking appliance
Data Source
AI summary
A heating device for tracking a resonance frequency includes a heating coil for heating a cooking appliance, a parallel resonance circuit including an inductor including the heating coil and a resonance capacitor resonating with the inductor, an inverter unit for supplying power to the parallel resonance circuit, a first current sensor for detecting an output current supplied from the inverter unit to the parallel resonance circuit, and a processor for controlling a driving frequency of the inverter unit so that a peak value of the output current detected by the first current sensor is smaller than a predetermined first threshold value.