Induction Hob Inverter Frequency Control to Eliminate Intermodulation Hum
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Solution Overview
Problem
Existing cooking appliance devices with induction heating elements experience intermodulation hum due to the difference in frequencies between inverters, which cannot be effectively avoided, leading to discomfort and inefficiencies in power output.
Innovation Solution
A cooking appliance device with a control unit that operates two inverters continuously at specific frequencies, ensuring the difference between integer multiples of these frequencies is at least 14 kHz or zero, and uses duty cycles to adapt average output power to target levels, thereby avoiding intermodulation hum and optimizing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two inverters are operated at different frequencies to adapt average output power, then power adaptability is improved, but intermodulation hum occurs due to frequency differences
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the operating frequencies of inverters based on power adaptation requirements. When power adaptation is needed, the control unit changes frequency parameters to ensure that the difference between integer multiples of inverter frequencies remains at least 14 kHz or zero, thereby maintaining power adaptability while preventing intermodulation hum in the audible range.
Solution Approach 2:
The patent implements feedback mechanisms where the control unit continuously monitors the operating state of inverters and adjusts frequencies accordingly. The system uses feedback to detect when power adaptation is required and automatically selects appropriate frequency combinations that satisfy the intermodulation hum avoidance condition while achieving the desired power output.
2Loss of energy
If inverters are operated discontinuously to adapt average output power, then power efficiency is improved, but operational complexity increases
Solution Approach 1:
The patent applies periodic action by using discontinuous operation of inverters in a structured, periodic manner. The control unit implements periodic switching patterns where inverters are switched on and off in controlled cycles to adapt average output power. This periodic approach maintains power efficiency while the control unit manages the complexity through systematic timing and frequency coordination.
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 solution achieves a high level of comfort by eliminating intermodulation hum, allows for precise adaptation of output power, and reduces operational costs through efficient frequency management and duty cycle adjustments.
Implementation Method 1
each of which operates a heating element designed as an induction heating element
Implementation Method 2
a heating element designed as an induction heating element
Data Source
Figure 1~2
Figure 3~4
AI summary
In order to provide a generic device with improved features with regard to high comfort, a cooking appliance device (10), in particular an induction hob device, is proposed, comprising at least two inverters (12, 14) and a control unit (16), which, when heating at least one heating configuration in at least one operating state, is designed to operate a first inverter (12) of the at least two inverters (12, 14) continuously at a first frequency (f1) and a second inverter (14) of the at least two inverters (12, 14) continuously at a second frequency (f2) and to adapt an average output power of the at least two inverters (12, 14) to a predetermined setpoint power, and which is designed to select the first frequency (f1) and the second frequency (f2) according to the condition, in order to avoid intermodulation hum,that the magnitude of the difference between an integer multiple (n) of the first frequency (f1) and an integer multiple (m) of the second frequency (f2) either takes on a value of at least 14 kHz or at least substantially the value of zero.