Induction Heating Inverter Current Stabilization
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Solution Overview
Problem
Induction heating devices using LC series resonant circuits experience issues with pot-floating and pot-displacement in non-magnetic pots, leading to unstable impedance and inverter current fluctuations, which can cause device overheating or failure.
Innovation Solution
The implementation of an induction heating apparatus with an LC parallel resonant circuit and a controller that adjusts the driving duty and frequency of the inverter current based on measured current levels to identify and mitigate pot-floating and pot-displacement, using sensors to manage the inverter current and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an LC series resonant circuit is used in the induction heating apparatus, then the heating efficiency is improved, but the inverter current fluctuates rapidly when pot-floating or pot-displacement occurs, causing device overheating and failure
Solution Approach 1:
The patent inverts the traditional LC series resonant circuit configuration to an LC parallel resonant circuit. This inversion fundamentally changes the impedance characteristics: while series resonance causes impedance to drop and current to surge during pot-floating, parallel resonance causes impedance to rise and current to decrease, thereby preventing the harmful current fluctuations that lead to overheating and device failure.
2Productivity
If the driving duty is increased to improve heating performance, then the heating speed is improved, but the inverter current exceeds safe limits causing device damage
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the inverter current and adjusts the driving duty accordingly. When pot-floating or pot-displacement is detected through current level analysis, the controller automatically reduces the driving duty to keep the inverter current within safe operating limits, preventing device damage while maintaining optimal heating performance.
3Power
If the inverter current is increased to enhance heating power, then the heating capability is improved, but the impedance becomes unstable during pot-floating, leading to device breakdown
Solution Approach 1:
The patent inverts the resonant circuit configuration from series to parallel, which fundamentally stabilizes the impedance characteristics during pot-floating events. The parallel resonant circuit naturally exhibits high impedance at resonance frequency, and when pot-floating occurs causing frequency deviation, the impedance increases rather than decreases, preventing the unstable low-impedance conditions that lead to device breakdown.
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 effectively stabilizes the inverter current and prevents overheating by adjusting the inverter's operation in response to pot-floating and pot-displacement, ensuring safe and efficient heating of both magnetic and non-magnetic pots.
Implementation Method 1
a heating coil configured to heat an object to be heated using an induction heating method
Implementation Method 2
The magnetic force is generated by an eddy current having a reverse phase in the non-magnetic pot and the eddy current is generated by a current flowing through the heating coil during the heating
Implementation Method 3
an LC parallel resonant circuit including a resonant capacitor connected in series with the heating coil and a resonance coil element connected in parallel to the resonant capacitor
Data Source
AI summary
An induction heating apparatus is provided. The induction heating apparatus includes a heating coil, an inverter, a current sensor configured to measure a driving current supplied from the inverter to the heating coil, and a controller configured to provide a drive signal to the inverter to allow the driving current to follow a target current based on a user input. The controller reduces a driving duty of the drive signal based on the driving current exceeding a predetermined reference current, and the controller provides a drive signal to the inverter to allow the driving current to follow a current less than the target current, based on the driving current being less than or equal to the predetermined reference current after reducing the driving duty of the drive signal.