Induction Hob Frequency Segmentation for Noise Suppression
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Solution Overview
Problem
Induction hobs with multiple induction heaters suffer from insufficient suppression of audible interference noise and flicker at the mains supply due to frequency differences between adjacent coils, which affects output power adaptation.
Innovation Solution
The induction hob employs distinct electronic driving means for each induction heater, with non-overlapping frequency ranges and different resonance frequencies, ensuring a constant power flow and minimizing interference noise by maintaining a frequency difference of at least 20 kHz between the driving means, even at varying power levels, thus avoiding flicker and allowing flexible output power adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output power of induction heaters is changed by adapting the frequency of AC current driven through induction coils, then the output power can be flexibly adjusted, but audible interference noise is generated due to frequency differences between adjacent coils
Solution Approach 1:
The patent divides the frequency spectrum into distinct, non-overlapping frequency ranges for different induction heaters. Each induction heater is assigned a specific frequency range, and the electronic driving means ensures that operating frequencies of adjacent heaters do not overlap, thereby preventing beat frequencies that cause audible noise while maintaining flexible power control within each segment.
Solution Approach 2:
The patent changes the frequency parameter of AC current driven through induction coils to control output power. By adapting the frequency within assigned non-overlapping ranges rather than using amplitude modulation, the system achieves flexible power adjustment without generating audible interference noise from frequency differences between adjacent coils.
2Power
If alternating frequencies are used to achieve certain output power at induction heaters, then output power control is possible, but interference noise is not suppressed sufficiently and flicker occurs at the mains supply
Solution Approach 1:
The patent segments the frequency spectrum into distinct non-overlapping ranges for different induction heaters. Each heater operates within its assigned frequency range, preventing frequency overlap that causes audible noise. The electronic driving means maintains constant power flow by adjusting frequency within these segmented ranges rather than using alternating frequencies, eliminating both noise and flicker.
Solution Approach 2:
The patent ensures continuous constant power flow to each induction heater by adjusting the frequency of AC current within assigned non-overlapping ranges. This continuous operation without alternating or modulating the power flow eliminates flicker at the mains supply while maintaining effective output power control through frequency adaptation.
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 effectively suppresses interference noise across a broad range of operating conditions while maintaining constant output power, preventing flicker at the mains supply and allowing for flexible power adjustments without generating audible noise.
Implementation Method 1
the induction coil is coupled with electronic driving means for driving an AC current through the induction coil. Said AC current generates a time verifying magnetic field. Due to the inductive coupling between the inductor coil and the piece of cookware placed on the induction hob, the magnetic field generated by the inductor coil causes eddy currents circulating in the piece of cookware. The presence of said eddy currents generates heat within the piece of cookware due to the electrical resistance of said piece of cookware.
Implementation Method 2
the magnetic field generated by the inductor coil causes eddy currents circulating in the piece of cookware. The presence of said eddy currents generates heat within the piece of cookware due to the electrical resistance of said piece of cookware.
Implementation Method 3
The presence of said eddy currents generates heat within the piece of cookware due to the electrical resistance of said piece of cookware.
Data Source
AI summary
An induction hob including a first heating region with a first induction coil and a second heating region with a second induction coil is provided. First and second resonant converters drive an AC current through the first and second induction coils. The first and second resonant converters form a half-bridge resonant converter that is continuously driven such that a direction of current flow through the first induction coil and the second induction coil is alternating. The half-bridge resonant converter controls the output power of the first and second heating regions by varying the frequency of the AC current through the respective induction coil. The first and second resonant converters have different resonance frequencies such that the resonance frequency of the first resonant converter is at least 1.4 times higher than the resonance frequency of the second resonant converter.