Interleaved PFC Choke Core Design for Low Magnetic Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing chokes for interleaved power factor correction (PFC) circuits are bulky and heavy, leading to inefficiencies and increased material usage due to strong magnetic coupling, which results in higher losses and larger network dimensions.
Innovation Solution
A two-coil single-core choke design with a core comprising multiple outer limbs and a smaller middle limb, featuring a coupling factor of less than 5%, achieved through strategically placed air gaps and different materials for the outer and middle legs to minimize magnetic overlap and flux cancellation, resulting in a compact and lightweight structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If two coils are wound on a common core with strong magnetic coupling, then magnetic flux is effectively utilized, but the core and choke become bulky and heavy
Solution Approach 1:
The core is segmented into multiple separate cores (first core and second core) instead of using a single common core. Each coil is wound on its own dedicated core, which allows for optimized core sizing and reduces the total volume and weight of the choke assembly while maintaining effective magnetic flux utilization in each individual core.
Solution Approach 2:
The invention transitions from a planar two-dimensional core layout to a three-dimensional arrangement where multiple cores are stacked or positioned in space. This dimensional change allows for more efficient use of magnetic flux paths and reduces the overall footprint and weight of the choke while maintaining the required inductance values.
2Ease of manufacture
If a common core is used for both coils, then manufacturing is simplified, but material usage and weight increase
Solution Approach 1:
The single common core is divided into multiple separate cores, each optimized for its specific coil's requirements. This segmentation reduces the total amount of core material needed while maintaining manufacturing simplicity through standardized core designs that can be produced using conventional techniques.
Solution Approach 2:
Each separate core can be designed with specific parameters (cross-sectional area, length, material properties) optimized for its associated coil's operating conditions. This allows for reduced material usage in each core compared to a single oversized common core, while the modular approach keeps manufacturing processes simple and scalable.
3Loss of energy
If strong magnetic coupling is maintained between coils, then flux cancellation is reduced, but losses and network dimensions increase
Solution Approach 1:
By separating the coils onto different cores, the invention achieves controlled magnetic coupling that minimizes unwanted flux cancellation effects. Each core carries its own magnetic flux independently, reducing circulating flux and associated losses while the compact arrangement of separate cores reduces the overall choke volume compared to traditional designs requiring larger margins for flux management.
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 design reduces material usage and weight while maintaining high efficiency by minimizing magnetic coupling, leading to lower losses and a more compact PFC circuit, suitable for applications in electric vehicles and hybrid technology.
Implementation Method 1
the core is designed such that the core sections form two loops with the middle leg as a common section, wherein each of the two coils lies on different loops outside the common section
Implementation Method 2
the magnetic fluxes from the coils add up, the core geometries are correspondingly large in order to achieve high magnetic permeability
Implementation Method 3
strategically placed air gaps and different materials for the outer and middle legs to minimize magnetic overlap and flux cancellation
Implementation Method 4
different materials for the outer and middle legs to minimize magnetic overlap and flux cancellation
Data Source
Figure 1A~1C
Figure 2~3
Figure 4~5
AI summary
The present invention relates to an inductor with two coils (20, 30) and a core (200) for interleaved applications in boost or buck converter circuits or power factor correction filters (PFC). The core (200) comprises several core sections with multiple outer legs (230, 240, 240-A, 240-B, 240-C, 240-D) and a central leg (250, 350, 450), wherein the core (200) is configured such that the coupling factor k of the two coils (20, 30) is less than 3% to 5%. Furthermore, the core (200) is configured such that the core sections form two loops with the central leg as a common section, each of the two coils (20, 30) being located on different loops outside the common section.The outer legs (230, 240, 240-A, 240-B, 240-C, 240-D) have a cross-section A1 and the middle leg (250, 350, 450) for the common section has a cross-section A2 < 2 x A1.