LCL-T Converter Magnetic Component With Controllable Leakage Path
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Solution Overview
Problem
Conventional magnetic components for galvanically isolated LCL-T resonant converters fail to integrate controllable leakage inductance due to the absence of a first-order leakage path, limiting their ability to optimize both core and winding losses.
Innovation Solution
A magnetic component design featuring a first and second core with unequal primary and secondary turns distributed around outer posts, and a center post that acts as a leakage path, allowing for controlled integration of controllable leakage inductance by adjusting air gaps and turns distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional planar magnetic design with E+I cores is used, then automated manufacturing and controlled parasitic parameters are improved, but controllable leakage inductance integration is lost due to absence of first order leakage path
Solution Approach 1:
The magnetic core is segmented into separate E-core and I-core portions with distinct winding regions. Primary windings are placed on the E-core while secondary windings are placed on the I-core, creating spatial separation that enables independent control of leakage inductance while maintaining automated PCB manufacturing capabilities.
Solution Approach 2:
Different regions of the magnetic component are assigned different functions: the E-core region handles primary winding with specific flux patterns, while the I-core region handles secondary winding with different flux patterns. This local functional differentiation enables controllable leakage inductance in specific areas without compromising overall manufacturing efficiency.
2Loss of energy
If E+I core design with interleaved windings is used, then AC losses in windings are limited, but leakage flux path is eliminated resulting in uncontrollable leakage inductance
Solution Approach 1:
The interleaved winding structure is segmented into primary windings on the E-core and secondary windings on the I-core. This segmentation maintains the AC loss benefits of interleaving by keeping windings close together, while simultaneously creating a controlled leakage path through the air gap between the segregated core portions.
Solution Approach 2:
An air gap is introduced as an intermediary element between the E-core and I-core portions. This air gap serves as a controlled leakage flux path that enables controllable leakage inductance while the windings remain positioned to minimize AC losses through their interleaved arrangement.
3Manufacturing precision
If U+I core design is used, then winding distribution is optimized for turns ratio, but flux flows through same path causing insignificant controllable leakage inductance
Solution Approach 1:
The U+I core structure is segmented into functionally distinct regions: the U-core portion accommodates primary windings with optimized turns distribution, while the I-core portion accommodates secondary windings. This segmentation preserves the precise turns ratio control of the U+I design while creating separate flux paths that enable controllable leakage inductance.
Solution Approach 2:
The flux path is differentiated into local regions: magnetizing flux flows through the connected U-I core path for efficient energy transfer, while leakage flux is directed through the air gap between segregated core portions. This local flux path differentiation enables controllable leakage inductance without compromising the precise turns ratio control.
4Productivity
If all fluxes link primary and secondary windings, then transformer action is efficient, but leakage inductance control is eliminated
Solution Approach 1:
The magnetic flux paths are segmented into magnetizing flux that links primary and secondary windings through the core for efficient transformer action, and leakage flux that is controlled through the air gap between segregated E-core and I-core portions. This segmentation enables both efficient energy transfer and controllable leakage inductance.
Solution Approach 2:
The magnetic circuit parameters are changed by introducing an air gap with specific reluctance. This parameter change creates a controlled leakage path that allows adjustment of leakage inductance while the main magnetic path maintains high coupling for efficient transformer action. The air gap reluctance serves as a controllable parameter for leakage inductance adjustment.
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 effectively integrates a resonant inductor and isolation transformer, optimizing both core and winding losses, and achieving enhanced power density and efficiency in high-frequency galvanically isolated DC-DC converters.
Implementation Method 1
the center post is used as a leakage path
Implementation Method 2
From the reluctance model of this transformer
Implementation Method 3
The center post of the first core and the second core are separated by a first air gap
Implementation Method 4
The first and second primary turns, the first and second secondary turns, and the first air gap are used to control and integrate a controllable leakage inductance
Implementation Method 5
all the fluxes generated by the primary winding has to link the secondary windings and vice versa
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A magnetic component (1) for a galvanically isolated LCL-T resonant converter is provided. The magnetic component (1) includes first and second cores (11, 12), a primary winding and a secondary winding. The first core (11) includes a first outer post (111), a second outer post (112), and a center post (113). The primary winding has primary turns including first primary turns (Np1) located around the first outer post (111) and second primary turns (Np2) located around the second outer post (112). The secondary winding has secondary turns including first secondary turns (Ns1) located around the first outer post (111) and second secondary turns (Ns2) located around the second outer post (112). The center post (113) of the first core (11) and the second core (12) are separated by a first air gap (g1). The turns distribution and the first air gap (g1) are used to control and integrate a controllable leakage inductance (Ll), where the center post (113) is used as a leakage path.