Induction Hob Frequency Control for Flicker and Noise
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Solution Overview
Problem
Cooking appliances, particularly induction hobs, face challenges in flexibly adjusting average output power while minimizing flicker and intermodulation noise, which affects the stability and efficiency of heating processes.
Innovation Solution
A cooking appliance device with multiple heating frequency units and a control unit that adjusts frequencies and time intervals to operate at different sets of frequencies, ensuring a flexible adjustment of average output power while minimizing flicker and intermodulation noise by using distinct frequency differences and duty cycles to maintain target power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If multiple heating frequency units operate simultaneously at fixed frequencies, then intermodulation noise is reduced, but flexibility in adjusting average output power is limited
Solution Approach 1:
The patent applies dynamics by making the operating frequencies of the heating frequency units time-dependent. The control unit dynamically switches between different frequency sets (first set with at least 20 kHz difference, second set with at least 14 kHz difference) based on time intervals, enabling flexible adjustment of average output power while maintaining sufficient frequency separation to minimize intermodulation noise throughout operation.
Solution Approach 2:
The patent changes the frequency parameter over time by alternating between two distinct frequency sets. The control unit adjusts which frequency set is active in each time interval, allowing the system to achieve different average output power levels while ensuring that within each interval, the frequency difference remains sufficient to prevent harmful intermodulation noise.
2Adaptability or versatility
If heating frequency units switch between different frequency sets in time intervals, then flexibility in average output power adjustment is improved, but flicker parameter may increase
Solution Approach 1:
The control unit monitors and calculates the flicker parameter resulting from switching between frequency sets and adjusts the time intervals and frequency selections accordingly. This feedback mechanism ensures that the switching strategy achieves flexible average output power adjustment while keeping the flicker parameter within acceptable limits by optimizing when to switch between the first and second frequency sets.
3Object-generated harmful factors
If frequency difference between heating units is increased to minimize intermodulation noise, then noise reduction is improved, but device complexity increases
Solution Approach 1:
The patent segments the operating spectrum into two distinct frequency sets: a first set with a minimum frequency difference of at least 20 kHz and a second set with a minimum frequency difference of at least 14 kHz. The control unit switches between these predefined sets based on time intervals, which simplifies the control logic compared to continuously calculating optimal frequencies, while still maintaining sufficient frequency separation to minimize intermodulation noise effectively.
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 solution allows for flexible adjustment of average output power, minimizes flicker and intermodulation noise, and adheres to legal standards, ensuring stable and efficient heating performance.
Implementation Method 1
The heating unit comprises a radiant heater, a resistance heater and/or preferably an induction heater, which is intended to convert electrical energy into heat indirectly via induced eddy currents
Implementation Method 2
The heating unit comprises a radiant heater, a resistance heater and/or preferably an induction heater, which is intended to convert electrical energy into heat indirectly via induced eddy currents
Data Source
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AI summary
The invention relates to a cooking appliance device with at least one first and at least one second heating frequency unit (10, 12) and with at least one control unit (14), which is provided to adjust a respective average output power (Pave1, Pave2) of the at least two heating frequency units (10, 12) while minimizing a flicker parameter (F) and to operate the at least two heating frequency units (10, 12) in at least one first time interval (TA) with a first set of frequencies (f1A, f2A) and in at least one second time interval (TB) with a second set of frequencies (f1B, f2B) that differs from the first set.In order to provide a generic cooking appliance that allows for advantageously flexible adjustment of an average output power, it is proposed that the frequencies (f1A, f2A) of the first set of frequencies (f1A, f2A) differ from each other by at least 14 kHz and that the frequencies (f1B, f2B) of the second set of frequencies (f1B, f2B) differ from each other by at least 14 kHz.