Induction Heating Control Using Bridge Modes and APWM
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Solution Overview
Problem
Existing induction heating apparatuses struggle to efficiently heat various types of containers with different features, leading to potential overheating and burning of switching elements due to inefficient power conversion and frequency modulation methods.
Innovation Solution
The induction heating apparatus adjusts its operation mode based on container resistance values, employing frequency doubler, half bridge, and full bridge modes, along with asymmetric pulse width modulation and phase shift power control methods to maintain efficient power output without increasing driving frequency, thereby reducing the risk of switching element overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pulse frequency modulation method is used to adjust output power, then power level can be controlled, but power conversion efficiency deteriorates and switching elements may be burned out
Solution Approach 1:
The patent changes the control parameter from driving frequency to duty ratio of switching signals. By using pulse width modulation (PWM) where the duty ratio can be adjusted between 0% and 100%, the system achieves continuous power control while maintaining constant driving frequency, thus avoiding efficiency deterioration and switching element damage associated with frequency changes.
2Temperature
If driving frequency is increased to heat low efficiency containers, then heating capability is improved, but switching elements overheat and may be burned out
Solution Approach 1:
The patent changes the control approach from frequency modulation to pulse width modulation. By maintaining a fixed, safe driving frequency and adjusting only the duty ratio of switching signals, the system achieves the required heating capability through controlled power delivery without causing switching element overheating that would result from increasing driving frequency.
3Power
If asymmetric pulse width modulation is used for power control, then efficient power delivery is maintained, but control complexity increases
Solution Approach 1:
The patent implements asymmetric pulse width modulation where the duty ratios of complementary switching signals are dynamically adjusted independently. This allows efficient power delivery by optimizing the on-time of each switching element based on load conditions, while the control complexity is managed through coordinated control of the asymmetric duty ratios to maintain synchronization and avoid conflicts.
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 approach allows for efficient heating of diverse containers while minimizing the risk of switching element damage, ensuring stable power delivery and improved power conversion efficiency across varying power levels.
Implementation Method 1
an induction magnetic field is generated around the working coil disposed in the induction heating apparatus. When magnetic line of force of the induction magnetic field passes through a bottom of the metallic container over the working coil, eddy current is generated inside the bottom of the container
Implementation Method 2
eddy current is generated inside the bottom of the container. When the eddy current flows in the container, and the container itself is heated
Data Source
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AI summary
An induction heating apparatus according to one embodiment may confirm a feature of a container and determine an operation mode based on the feature of the container before performing an operation of heating the container. In one embodiment, the operation mode of the induction heating apparatus may be determined as any one of a frequency doubler mode, a half bridge mode, and a full bridge mode. In one embodiment, a power control mode of the induction heating apparatus may be determined based on an operation mode of the induction heating apparatus. In one embodiment, the power control mode of the induction heating apparatus may be determined as any one of an asymmetric pulse width modulation (APWM) mode and a phase shift mode.