Induction Heating Resonance Capacitance Adjustment
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Solution Overview
Problem
Existing induction heating devices for household appliances face challenges in achieving high electrical efficiency and maximum heating output, particularly in efficiently managing the resonance frequency and inductor configurations to minimize switching losses and maximize performance.
Innovation Solution
The proposed solution involves a domestic appliance induction heating device with a heating frequency unit operating multiple inductors in parallel, a resonance unit coupled to the heating frequency unit, and a control unit that adjusts the resonance unit's capacitance based on the number of inductors operated, allowing for efficient power conversion and flexible resonance frequency management, thereby achieving high efficiency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple inductors are operated in parallel to increase heating output, then the maximum heating power is improved, but the switching losses increase and electrical efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by making the resonance capacitance adjustable rather than fixed. The control unit dynamically selects different capacitance values from the resonance unit based on the number of active inductors, allowing the system to adapt to changing operating conditions and minimize switching losses at each power level.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the resonance unit to optimize system performance. By adjusting the resonance capacitance according to the number of parallel inductors, the system maintains optimal resonance frequency and minimizes switching losses across different power output levels.
2Loss of energy
If the resonance capacitance is fixed, then the device complexity is reduced, but the ability to maintain high efficiency across different operating modes deteriorates
Solution Approach 1:
The patent segments the resonance capacitance into multiple discrete values that can be independently selected. The resonance unit is divided into multiple capacitive elements that can be switched in and out, allowing the control unit to select the appropriate capacitance value for each operating mode without requiring a completely different circuit design.
Solution Approach 2:
The resonance unit is designed to serve multiple functions: it can operate with different capacitance values to support different numbers of parallel inductors, maintaining high efficiency across various operating modes while using a single unified circuit structure rather than separate circuits for each mode.
3Productivity
If switching frequency is increased to improve heating performance, then the heating speed is improved, but switching losses increase and efficiency decreases
Solution Approach 1:
The patent utilizes periodic resonance action by tuning the resonance unit to work at or near its resonant frequency. This periodic resonance enables efficient energy transfer and heating while allowing the system to operate at lower switching frequencies, thereby reducing switching losses while maintaining high heating performance.
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 configuration results in low switching losses, high comfort, and high overall performance by shifting the resonance curve to frequencies above 20 kHz, enabling efficient power delivery and flexible operation modes.
Implementation Method 1
an alternating electromagnetic field which is intended to be converted into heat in an advantageously metallic, preferably ferromagnetic, cooking utensil or oven heating element by means of eddy currents and/or magnetic reversal effects
Implementation Method 2
a resonance unit that is coupled to the heating frequency unit at least in the operating mode, wherein the control unit is provided to adjust a size of the resonance unit
Implementation Method 3
a heating frequency unit, in particular an inverter, which preferably has at least two, preferably series-connected, bidirectional unipolar switches
Data Source
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AI summary
The invention relates to a household appliance induction heating device (12), in particular a cooktop induction heating device, comprising at least one heating frequency unit (30), at least two inductors (20, 22, 24, 26) which are operated in parallel by the heating frequency unit (30) in at least one operating mode, at least one resonance unit (40; 40a; 40b) which is coupled to the heating frequency unit (30) at least in that operating mode, and at least one control unit (18). To achieve high efficiency and/or high maximum heating power, it is proposed that the control unit (18) be designed to adjust the size of the resonance unit (40; 40a; 40b) in at least one operating mode, depending on the number of inductors (20, 22, 24, 26) operated in parallel by the heating frequency unit (30).