High-Frequency Heating Device Current Feedback Control
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Solution Overview
Problem
Conventional high-frequency heating devices face challenges in controlling maximum current and providing effective over-current protection, leading to high resource consumption and strict timing requirements for the switching element, particularly in the voltage control mode.
Innovation Solution
A method and apparatus that control the switching element of a high-frequency heating device using a control signal with a preset duty ratio, detecting real-time current and turning off the element when it exceeds a preset reference value, and turning it on during the next available window, thereby reducing maximum current and enhancing over-current protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If voltage control mode is adopted to regulate output power by controlling on-off time of IGBT, then output power regulation is achieved, but maximum current cannot be controlled and requirements for switching element become high
Solution Approach 1:
The patent implements current feedback control by detecting the real-time current flowing through the IGBT and comparing it with a preset current reference value. When the detected current reaches the reference value, the control signal immediately terminates the IGBT conduction. This feedback mechanism ensures that the maximum current is controlled within safe limits while maintaining output power regulation capability.
Solution Approach 2:
The patent replaces the conventional voltage-based control mechanism with a current-based control mechanism. Instead of controlling output power solely through voltage and timing parameters, the system directly controls the current flowing through the IGBT by detecting current magnitude and using it as the primary control parameter for terminating conduction.
2Adaptability or versatility
If sequential control mode is used to adjust IGBT driving, then software control flexibility is achieved, but controller resource consumption increases and over-current protection cannot be performed timely
Solution Approach 1:
The patent implements self-service control where the IGBT's conduction termination is automatically determined by the current detection circuit itself. When the current reaches the reference value, the control logic immediately stops conduction without requiring complex software sequencing. This reduces controller computational burden while maintaining control flexibility through programmable current reference values.
Solution Approach 2:
The patent sets preset current reference values in advance that define safe operating limits. The control system continuously monitors current against these pre-established thresholds, enabling proactive over-current protection before damage can occur, rather than reacting after over-current conditions have already caused harm.
3Device complexity
If conventional control mode operates without real-time current monitoring, then control simplicity is maintained, but over-current protection is ineffective and elements may be damaged
Solution Approach 1:
The patent introduces real-time current feedback monitoring by continuously detecting the current flowing through the IGBT and comparing it with preset reference values. This feedback loop provides immediate over-current protection while maintaining relatively simple control logic that can be implemented in standard microcontrollers.
Solution Approach 2:
The patent combines voltage control and current control mechanisms into a composite control system. The system uses both voltage-based timing control and current-based protective control, creating a hybrid approach that leverages the advantages of both methods while mitigating their individual disadvantages.
Data Source
AI summary
Disclosed is a method for controlling a power supply of a high-frequency heating device, comprising: controlling a switching element of the high-frequency heating device to operate according to a control signal with a preset duty ratio; detecting a real-time current flowing through the switching element; and if the real-time current is greater than or equal to a preset current reference value, controlling the switching element to turn off, and controlling the switching element to turn on when a next turn-on window of the control signal comes. The method may reduce a maximum current during an operation of the switching element, thus reducing requirements for the switching element and enabling an effective over-current protection. Further disclosed is an apparatus for controlling a power supply of a high-frequency heating device and a high-frequency heating device with the apparatus for controlling the power supply.