Induction Cooktop Control Using Variable Switching Frequencies
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Solution Overview
Problem
Existing induction cooktop control strategies cannot supply all desired combinations of power to multiple induction heaters, limiting their operational flexibility and efficiency.
Innovation Solution
An induction cooktop with a control unit that operates two switching converters with different switching frequencies, allowing for various power combinations by adjusting the duration of control periods and switching frequency differences within specific thresholds, enabling the delivery of a wider range of power values to the induction heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control strategy uses fixed switching frequency values for multiple induction heaters, then the control is simple, but the available power combinations are limited
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control unit adjusts the switching frequency of the converters dynamically within a range around a nominal value, allowing the system to adapt to different power combination requirements. This resolves the contradiction by enabling continuous adjustment of power delivery without requiring a completely complex control architecture.
Solution Approach 2:
The patent changes the parameter of switching frequency from a fixed value to a variable parameter that can be adjusted within a specific range. By allowing the switching frequency to vary around a nominal value, the system can achieve a continuous range of power combinations for multiple induction heaters, thereby improving adaptability while maintaining manageable control complexity.
2Object-affected harmful factors
If the switching converters operate at the same frequency, then the control is simple, but audible noise and electrical interference increase
Solution Approach 1:
The patent applies local quality by assigning different switching frequencies to different converters operating in parallel. Each converter operates at a slightly different frequency (varying around their respective nominal values), which locally differentiates their operational characteristics. This prevents the harmful resonance and interference that would occur if all converters operated at the exact same frequency, while maintaining relatively simple control for each individual converter.
3Adaptability or versatility
If the control period is divided into fractions with different switching frequencies, then more power combinations are available, but the control complexity increases
Solution Approach 1:
The patent simplifies the control period structure by allowing each converter to continuously operate throughout the control period at its own variable frequency, rather than dividing the control period into fractions where converters are activated sequentially. This dynamic approach maintains adaptability for achieving various power combinations while avoiding the complexity of time-sharing control schemes.
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 enhances the ability to supply a broader range of power combinations to induction heaters, improving operational flexibility and efficiency while minimizing audible noise and avoiding electrical or thermal overstress.
Implementation Method 1
induction cooktop may comprise at least one pair of high frequency switching converter... configured to energize respective induction heaters (also referred to as 'pancake coils')
Implementation Method 2
energize the first induction heater and the second induction heater, respectively
Data Source
AI summary
An induction cooktop is provided that includes a first induction heater and a second induction heater; a control unit; a first switching converter and a second switching converter, operable, preferably cyclically, by the control unit in a control period to energize the first induction heater and the second induction heater, respectively; wherein the control unit is configured to operate, preferably in a first working mode, and wherein: (i) during at least a first fraction of the control period operate simultaneously the first switching converter with a first switching frequency value and the second switching converter with a second switching frequency value, wherein a frequency switching difference between the two switching frequencies values is equal to a value comprised between a first frequency threshold and a second frequency threshold or is above a third frequency threshold.