Induction Hob Coil Activation Scheduling for Noise Reduction
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Solution Overview
Problem
Induction hobs experience acoustic noise and uneven heating due to interference between adjacent induction coils operating at different frequencies, and existing solutions fail to effectively manage power distribution across multiple coils.
Innovation Solution
A method for controlling induction hobs using a master-slave power unit configuration, where a master power unit calculates and schedules the activation of multiple induction coils to minimize acoustic noise and ensure balanced heating, by defining coil activation schedules and frequency ranges to optimize power delivery and heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If adjacent induction coils are operated at different frequencies to provide different power levels, then power level differentiation is achieved, but acoustic noise occurs due to interference between coils
Solution Approach 1:
The patent implements periodic switching of coil activation in a time-multiplexed manner. Coils are activated in alternating time intervals rather than simultaneously, creating a periodic pattern where only one coil is active at any given moment. This eliminates continuous interference between different frequencies while still delivering the required power levels to multiple zones over time.
Solution Approach 2:
The system dynamically adjusts the activation schedule of induction coils based on real-time power requirements. The control method calculates optimal activation patterns that adapt to changing cooking demands, switching which coils are active and for how long, thereby dynamically balancing power distribution while avoiding acoustic interference.
2Area of stationary object
If multiple induction coils are activated simultaneously to heat large cookware, then heating coverage is improved, but uneven heating occurs due to interference between adjacent coils
Solution Approach 1:
The control method uses periodic time-multiplexed activation where coils are switched on and off in alternating intervals. This ensures that while multiple coils serve a large area, they do not operate simultaneously at different frequencies, thereby preventing interference patterns that would cause uneven heating. Each coil receives dedicated activation periods ensuring uniform energy distribution.
3Power
If induction coils are switched on and off frequently to control power levels, then power control precision is improved, but flicker and power fluctuations occur
Solution Approach 1:
The system employs periodic activation patterns with carefully calculated duty cycles. By controlling the on/off timing and duration of each coil in a regular periodic pattern, the system achieves precise average power control while maintaining stable overall power delivery. The periodic nature allows for predictable power averaging that reduces flicker effects.
Solution Approach 2:
The control method merges the activation patterns of multiple coils into a coordinated schedule. By combining the periodic activation of individual coils into a unified time-multiplexed sequence, the system achieves both precise power control for each zone and overall power stability, as the total power delivery remains consistent while individual coil activation is precisely controlled.
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
The method significantly reduces acoustic noise and achieves uniform heating by dynamically controlling the activation of induction coils, ensuring balanced power distribution and improved heat transfer to cookware, while reducing flicker and power fluctuations.
Implementation Method 1
the induction coil is coupled with electronic driving means, in the following referred to as power unit, for driving an AC current through the induction coil
Implementation Method 2
for heating a piece of cookware placed on the heating zone
Data Source
AI summary
The invention relates to a method for controlling an induction hob (1), the induction hob (1) comprising a plurality of induction coils (3) and two or more power units (4), each power unit (4) being coupled with one or more induction coils (3), wherein a cooking zone is formed by associating one or more induction coils (3) to a coil group (6.1-6.4), the method comprising the steps of: —defining one or more coil groups (6.1-6.4), each coil group (6.1-6.4) being associated with one or more induction coils (3); —calculating a relative power value or relative electrical parameter value of each coil group (6.1-6.4) based on a maximum power value or maximum electrical parameter value, the maximum power value being the power value of the coil group with the highest power request, respectively, the maximum electrical parameter value being an electrical parameter value of the coil group (6.1-6.4) with the highest power request; —calculating, for each coil group (6.1-6.4), a coil activation number based on the relative power value or relative electrical parameter value, the coil activation number being the number of induction coils (3) to be activated in subsequent steps of a coils activation sequence; —establishing a coils activation schedule based on the coil activation number; —operating the induction hob (1) according to the coils activation schedule. wherein the power units (4) are operated according to a master-slave configuration, wherein a master power unit is adapted to calculate the coil activation number, establish the coils activation schedule and operate the plurality of induction coils (3) of a master power unit and one or more slave power units according to the coils activation schedule.