Resonant LLC Converter Multi-Leg Transformer Flux Integration
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Solution Overview
Problem
Existing power conversion devices face challenges in size reduction and loss minimization due to the separate treatment of different magnetic components, such as transformers and DC reactors, which leads to inefficiencies in magnetic flux cancellation and increased component size and losses.
Innovation Solution
A magnetic component assembly is developed, where windings are magnetically coupled and integrated with a multi-leg core, allowing DC and AC magnetic fluxes to merge or cancel within the core, thereby contributing to the inductance of the DC reactor and reducing leakage flux and eddy current losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If separate magnetic components (transformer and DC reactor) are used, then device functionality is achieved, but device size and losses increase
Solution Approach 1:
The patent combines the transformer and DC reactor into a single integrated magnetic component with a multi-leg core structure. The transformer windings and DC reactor winding share the same core, allowing DC magnetic fluxes from both windings to merge in the same direction at the center leg, thereby reducing the overall magnetic component size while maintaining functionality.
Solution Approach 2:
The multi-leg core structure serves multiple functions simultaneously: it supports transformer windings for AC power conversion, accommodates DC reactor windings for current ripple filtering, and provides a path for DC magnetic flux merging. This multi-functionality eliminates the need for separate magnetic components.
2Ease of manufacture
If DC reactor and transformer are integrated with separate cores, then functionality is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent merges the transformer core and DC reactor core into a single multi-leg core structure, eliminating the need for separate cores and reducing assembly complexity. The integrated core allows for unified manufacturing and simpler installation.
Solution Approach 2:
The core is segmented into multiple legs (first side leg, second side leg, center leg) with specific functions assigned to each, allowing for modular winding placement while maintaining a unified structure that simplifies overall manufacturing.
3Loss of energy
If AC magnetic flux cancellation is implemented at the gap, then leakage flux is reduced, but DC magnetic flux saturation occurs
Solution Approach 1:
The core is divided into AC flux paths (side legs) and DC flux path (center leg), allowing AC magnetic fluxes to cancel at the gap while DC magnetic fluxes merge at the center leg without saturation. This segmentation enables independent optimization of AC and DC flux characteristics.
Solution Approach 2:
The center leg acts as an intermediary that carries the merged DC magnetic fluxes from both the DC reactor winding and transformer windings, preventing DC flux saturation while allowing AC flux cancellation at the gap portion.
4Volume of moving object
If multiple windings are wound around the same leg, then component size is reduced, but winding complexity and losses increase
Solution Approach 1:
The patent assigns different windings to different legs of the multi-leg core: DC reactor winding on the center leg and transformer windings on the side legs. This segmentation minimizes eddy current losses by reducing magnetic flux leakage while maintaining compact component volume.
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 integration results in size reduction and loss minimization by utilizing the turns of different windings to enhance the inductance of the DC reactor and eliminate AC leakage flux, leading to more efficient power conversion.
Implementation Method 1
winding directions of the windings of the winding coupled body and the winding of the DC reactor are set so that magnetic fluxes generated by DC currents flowing through the windings of the winding coupled body and the winding of the DC reactor merge in the same direction at the center leg of the multi-leg core
Implementation Method 2
a center leg having a gap portion, wherein the n number of windings of the winding coupled body are wound around the respective side legs of the multi-leg core, a winding of the DC reactor is wound around the center leg of the multi-leg core
Data Source
AI summary
A first winding, a second winding, a fourth winding, and a fifth winding functioning as a transformer are wound around respective side legs of a three-leg core. Third windings functioning as a DC reactor are wound around a center leg. Winding directions of the first winding, the second winding, and the third windings are set so that magnetic fluxes generated by DC currents flowing through the respective windings merge in the same direction at the center leg, and winding directions of the fourth winding and the fifth winding are set so that magnetic fluxes generated by AC currents flowing through the respective windings cancel each other at the center leg. Thus, the transformer and the DC reactor are integrated using the three-leg core, whereby size reduction and loss reduction of the integrated magnetic component are achieved.