Induction Heating Inverter Control for Switching Loss Detection
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Solution Overview
Problem
Induction heating apparatuses face inefficiencies and potential damage to switching elements due to abnormal operation caused by changes in the position of a container during heating, leading to increased switching loss and risk of element burnout.
Innovation Solution
A controller measures resonance current and driving voltage values to determine the operational state, identifying abnormal conditions by comparing an overlapped period with a reference time point, and adjusts the driving frequency to prevent switching element damage by stopping or re-driving the working coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the container position changes during heating operation, then the heating performance may be maintained, but the switching elements are at risk of burnout due to abnormal operation in capacitive areas
Solution Approach 1:
The controller continuously monitors the operational state of the induction heating apparatus by measuring resonance frequency and detecting whether the operating frequency falls within capacitive areas. Based on this feedback, the controller automatically adjusts or stops the driving frequency to prevent switching element burnout, thereby resolving the contradiction between maintaining heating operation and preventing harmful effects.
Solution Approach 2:
The system dynamically adjusts the driving frequency based on real-time detection of operational conditions. When the container position changes causing the operating frequency to enter capacitive areas, the controller dynamically modifies the driving parameters or stops operation, enabling the system to adapt to changing conditions and avoid switching element damage.
2Device complexity
If the driving frequency is fixed, then the control system is simple, but the switching elements may be damaged when operating frequency enters capacitive areas due to container position changes
Solution Approach 1:
The controller incorporates feedback mechanisms that monitor resonance frequency and detect capacitive area operation. This feedback enables automatic adjustment of driving frequency without requiring complex manual intervention, balancing system simplicity with switching element protection.
Solution Approach 2:
The system performs self-diagnosis by detecting its own operational state through resonance frequency measurement. The controller automatically determines when operating frequency enters capacitive areas and takes corrective action, enabling the system to protect itself without external intervention while maintaining relatively simple control architecture.
3Reliability
If the controller continuously monitors operational state, then switching element damage is prevented, but the system complexity and processing requirements increase
Solution Approach 1:
The monitoring system uses feedback from resonance frequency measurements to trigger protective actions only when necessary. By monitoring key parameters and comparing them against predetermined thresholds for capacitive area detection, the system achieves reliable protection without requiring excessively complex continuous analysis of all operational parameters.
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
Prevents switching element burnout by detecting abnormal operation and adjusting the driving frequency, ensuring reliable and efficient induction heating performance.
Implementation Method 1
an induced magnetic field is generated around the working coil disposed in the induction heating apparatus. When magnetic line of force of the induced magnetic field generated 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. Accordingly, the eddy current generated flows in the container, and the container itself is heated
Data Source
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AI summary
A controller of the induction heating apparatus in one embodiment may generate an overlapped period of a resonance current value of a working coil and a driving voltage value of a switching element included in an inverter circuit. In the disclosure, the overlapped period may denote a period for which the resonance current value and the driving voltage value are all positive numbers. The controller may determine whether a driving state of the induction heating apparatus is normal or abnormal based on a time point at which the overlapped period appears. When determining that the driving state of the induction heating apparatus is abnormal, the controller may stops driving of the working coil.