Litz Cable Inductor for High-Frequency Eddy Current Loss Reduction
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Solution Overview
Problem
High-frequency induction heating devices face inefficiencies due to energy losses in the inductor and capacitive circuit, particularly at higher frequencies, leading to reduced overall energy efficiency.
Innovation Solution
The use of Litz cables with multiple insulated strands connected in parallel to a metal bar, forming a fan-shaped configuration to reduce high-frequency eddy current losses, combined with a capacitive circuit and cooling mechanisms to manage heat and current distribution effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional single-strand conductors are used in the inductor, then the construction is simple, but high-frequency eddy current losses increase significantly
Solution Approach 1:
The conductor is divided into multiple insulated strands (Litz cable configuration) that are twisted together. This segmentation prevents eddy current losses by ensuring that adjacent strands have opposite polarities, causing eddy currents to cancel each other out. The patent applies this by using multi-strand Litz cables with specific twist ratios to minimize eddy current generation while maintaining electrical conductivity.
Solution Approach 2:
The patent uses composite conductor structures combining multiple insulated strands with different orientations. The Litz cable comprises several wires twisted together in a specific configuration, creating a composite structure that simultaneously provides high electrical conductivity and suppresses eddy current losses through the alternating polarity arrangement.
2Loss of energy
If the number of strands in parallel is increased to reduce eddy current losses, then energy efficiency improves, but the connection complexity and manufacturing difficulty increase
Solution Approach 1:
The connection process is segmented into modular steps where pre-assembled strand bundles are connected to terminal bars. This segmentation simplifies manufacturing by allowing parallel connection of multiple strands in organized groups rather than individually, reducing the complexity of handling and connecting numerous thin wires.
Solution Approach 2:
Terminal bars serve as intermediary elements that facilitate the connection between multiple Litz cable strands and the external circuit. The terminal bars provide a structured interface that simplifies the parallel connection process, allowing multiple strands to be connected systematically without complex wiring arrangements.
3Power
If high current intensity is used to achieve high heating power, then heating efficiency improves, but energy losses in the inductor increase
Solution Approach 1:
The high current is distributed across multiple parallel strands, reducing the current density in each individual strand. This segmentation approach allows the inductor to handle high total power while minimizing eddy current losses in each strand, as the alternating polarity arrangement causes eddy currents to cancel out in the multi-strand configuration.
Solution Approach 2:
The patent changes the electrical parameters of the conductor by using Litz cable with specific twist ratios and strand configurations. This parameter change optimizes the balance between electrical conductivity and eddy current suppression, allowing efficient high-power operation with reduced losses.
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 significantly reduces energy losses in the inductor and capacitors, maintaining constant current density and improving the overall energy efficiency of high-frequency induction heating devices.
Implementation Method 1
the diameter of a cable strand being chosen in such a way that it makes it possible to overcome the losses by high-frequency eddy currents generated by the neighboring conductors
Implementation Method 2
a power inductor for heating an element... the inductor, in the following description, is of the longitudinal flux type
Implementation Method 3
a capacitive circuit in the inductor circuit
Implementation Method 4
High frequency induction heating is efficient... the intensity of the current, for the heating power, can reach several hundred to several thousand amperes
Data Source
Figure 1~3
Figure 4~9
Figure 5~7
AI summary
The invention relates to an induction heating device comprising: a high frequency power supply; a power inductor (3) for heating an induced element, and a capacitive mounting in the inductor circuit, wherein the inductor (3) includes at least one cable (5a, 5b) having multiple fibers insulated from each other and surrounded by an insulating sheath, and the fibers, at the connecting end thereof, are fanned out (9.1, 9.2) to be connected in parallel to a metal bar (10.1, 10.2) forming a power supply terminal.