Induction Cooktop Coil Timing to Prevent Magnetic Interference Noise
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Solution Overview
Problem
Induction heating cooking apparatuses face magnetic field interference noise due to differing output frequencies between working coils, which affects the heating performance and user experience.
Innovation Solution
A cooking apparatus with a processor that adjusts the strength and timing of currents supplied to induction coils, using pulse width modulation (PWM) signals to control the driver switches, ensuring the average output power remains consistent across heating areas and minimizing frequency differences between coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple induction coils are driven simultaneously with different output frequencies, then each coil can operate at its optimal frequency for heating performance, but magnetic field interference noise occurs between the coils
Solution Approach 1:
The patent applies periodic action by sequentially driving induction coils in time-divided periods rather than simultaneously. The processor controls the driver to operate each coil in separate time slots, creating a periodic driving pattern that eliminates magnetic field interference between coils while maintaining overall heating effectiveness through coordinated sequential operation.
Solution Approach 2:
The patent implements preliminary action by having the processor pre-determine the driving sequence and frequency allocation for multiple induction coils before operation begins. The system calculates and sets the optimal driving frequencies and time slots in advance, ensuring that each coil operates at its optimal frequency without causing interference to others during the actual heating process.
2Power
If the strength of current supplied to induction coils is increased to improve heating output, then heating power increases, but magnetic field interference noise becomes more severe
Solution Approach 1:
The patent uses periodic action to alternate the operation of multiple induction coils in time-divided sequences. By controlling the driver to activate only one coil at a time in each period, the system maintains high heating power output when needed while eliminating the simultaneous magnetic field interference that would occur with parallel high-power operation.
Solution Approach 2:
The patent applies dynamics by making the driving frequency and current strength adjustable and time-dependent. The processor dynamically modifies the operating parameters of each coil based on the current time slot and operational requirements, allowing high current strength for individual coils during their active periods while preventing interference through temporal separation.
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
Prevents noise generation from other heating areas when turning on a heating zone, maintains consistent current strength, and protects the apparatus from voltage thresholds, allowing for smooth Joule heat generation without noise interference.
Implementation Method 1
induction heating cooking apparatuses which do not generate fine dust and harmful gases and cause little risk of an outbreak of fire, unlike conventional heating apparatuses which use fossil fuels such as gases or oils
Implementation Method 2
Such induction heating cooking apparatuses can generate Joule heat by resistance components of a cooking container itself by using the principle of induction heating, and heat the container by using the Joule heat
Data Source
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AI summary
A cooking apparatus is disclosed. The cooking apparatus includes a cooking plate including a plurality of heating areas, a plurality of induction coils in locations corresponding to each of the plurality of heating areas in the lower part of the cooking plate, a driver supplying currents to each of the plurality of induction coils, and a processor. The processor is configured to, based on a user instruction for turning on a second heating area among the plurality of heating areas being received while a first heating area among the plurality of heating areas is turned on, stop the supply of a current to a first induction coil corresponding to the first heating area among the plurality of induction coils during a threshold time.