Interleaved LLC Converter Variable Inductor Current Control
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Solution Overview
Problem
Interleaved LLC converters face challenges in balancing output currents due to component tolerances, leading to differing resonance frequencies and operating points, which affects efficiency and electromagnetic compatibility, and requires improvements in current-controlled variable inductors to reduce size and losses.
Innovation Solution
A magnetic core assembly with air gaps and a current-controlled variable inductor design, where a first coil generates a magnetic flux through a magnetic core assembly with air gaps, and a second coil adjusts the inductance by varying the DC current, allowing for efficient control of inductance and resonance frequency balancing across multiple LLC converter units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard tolerances of circuit components are used in tank circuits, then manufacturing cost is reduced, but resonance frequencies of individual LLC converter units differ significantly leading to load imbalance
Solution Approach 1:
The patent employs current-controlled variable inductors (CCVIs) that dynamically adjust their inductance values based on control currents. This allows the resonance frequencies of individual LLC converter units to be tuned and balanced, compensating for component tolerances and ensuring equal load distribution among parallel units.
Solution Approach 2:
The invention changes the inductance parameter of the tank circuits by using CCVIs whose inductance can be varied through control currents. This parameter adjustment enables precise tuning of resonance frequencies to achieve load balance despite variations in other circuit components.
2Reliability
If current-controlled variable inductors with magnetic cores are used to balance load, then resonance frequency tuning is achieved, but power losses and electromagnetic stray fields increase
Solution Approach 1:
The patent introduces magnetic shielding material locally at specific positions within the magnetic core structure, particularly at air gaps and interfaces. This localized approach reduces electromagnetic stray fields and eddy current losses without requiring complete redesign of the entire magnetic core, thereby minimizing power losses while maintaining load balancing capability.
3Volume of moving object
If higher frequency operation is implemented, then converter size is reduced, but power losses and electromagnetic interference increase
Solution Approach 1:
The patent converts the potentially harmful electromagnetic stray fields and eddy currents generated at higher frequencies into beneficial effects by using magnetic shielding material that directs and contains the magnetic flux. The shielding material transforms what would be loss-generating stray fields into controlled magnetic paths, enabling high-frequency operation with reduced interference and losses.
4Object-affected harmful factors
If magnetic shielding material is added to reduce stray fields, then electromagnetic compatibility is improved, but device complexity increases
Solution Approach 1:
The patent applies magnetic shielding material selectively at critical locations within the magnetic core assembly, such as at air gaps and interfaces between core components. This localized application reduces stray fields and eddy current losses without requiring complete shielding of the entire magnetic path, thereby limiting the increase in device complexity to only essential areas.
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 solution enhances the efficiency and electromagnetic compatibility of interleaved LLC converters by reducing power losses and stray fields, enabling operation at higher frequencies with a smaller magnetic core size, effectively balancing output currents and improving overall performance.
Implementation Method 1
a first coil (6) that is arranged on the first portion of the magnetic core assembly and that is configured to generate a magnetic flux in a magnetic path that includes the first portion of the magnetic core assembly, the two or more air gaps and a part of the second portion of the magnetic core assembly
Implementation Method 2
a second coil (5) that is arranged on the second portion of the magnetic core assembly and that is configured to generate a bias magnetic field in the second portion of the magnetic core assembly when a direct current is supplied to the second coil (5)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An inductive component is described herein. In accordance with one example, the inductive component includes a magnetic core assembly comprising at a first portion and a second portion, which is magnetically separated from the first portion of the magnetic core assembly via two or more air gaps. The inductive component further includes an inductor with a variable inductance including a first coil that is arranged on the first potion of the magnetic core assembly, a second coil arranged on the second portion of the magnetic core assembly and configured to generate a bias magnetic field in the second portion of the magnetic core assembly. The first coil is configured to generate a magnetic flux in a magnetic path that includes the first potion of the magnetic core assembly, the two or more air gaps and a part of the second portion of the magnetic core assembly. Furthermore, multiphase LLC switching converter, which includes the above-mentioned inductive component is described herein.