Stacked Core LLC Converter Flux Cancellation
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Solution Overview
Problem
LLC resonant converters face limitations in efficiency and power density due to core loss and winding loss, particularly at high switching frequencies, which hinder their ability to support higher power densities and efficiencies.
Innovation Solution
The integration of stacked core cell structures for magnetic circuits that magnetically couple primary and secondary windings, along with the use of gallium nitride transistors and compact PCB designs, reduces core fringing losses and enhances thermal efficiency, allowing for higher frequency operation and increased power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high switching frequencies are used to reduce magnetic component size, then power density increases, but core loss and winding loss increase resulting in poor efficiency
Solution Approach 1:
The magnetic circuit is divided into multiple stacked core cells (first core cell, second core cell, third core cell) with distinct windings for resonant inductor and transformer functions. This segmentation allows optimized magnetic paths for each function, reducing overall core loss while maintaining high switching frequency operation for high power density.
Solution Approach 2:
The patent integrates the resonant inductor and transformer into a single stacked core structure where multiple core cells are magnetically coupled. This merging of functions into one integrated magnetic component reduces the total magnetic component size (increasing power density) while the optimized magnetic coupling minimizes winding loss and core loss.
2Device complexity
If conventional magnetic circuits are used, then结构简单 (structure is simple), but core fringing losses increase reducing thermal efficiency
Solution Approach 1:
The patent uses a three-dimensional stacked core configuration where core cells are arranged vertically with magnetic coupling between layers. This dimensional arrangement optimizes magnetic flux paths and reduces fringing losses compared to planar configurations, while the stacked structure itself provides the required magnetic circuit functionality.
Solution Approach 2:
Different core cells in the stack are optimized for specific functions: the first core cell for resonant inductor, the second for transformer, and the third for additional magnetic coupling. Each local region of the magnetic circuit is tailored to minimize losses for its specific function, reducing overall core fringing losses while maintaining structural feasibility.
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 significantly reduces core and winding losses, enabling LLC resonant converters to achieve higher efficiencies and power densities, facilitating compact, high-performance designs suitable for applications like server and telecommunication systems.
Implementation Method 1
provide a single magnetic circuit to magnetically couple the primary side inductor winding with the transformer primary and secondary windings to facilitate flux cancellation
Implementation Method 2
magnetically couple the primary side inductor winding with the transformer primary and secondary windings to facilitate flux cancellation
Implementation Method 3
an inductor winding extending around the inductor core structure to provide the resonant circuit inductor
Implementation Method 4
primary and secondary windings extending around the transformer core structure
Data Source
AI summary
Disclosed examples include integrated magnetic circuits for LLC resonant converters, including an inductor cell and multiple transformer cells with cores arranged in a stack structure. The individual transformer cells include primary and secondary windings extending around the transformer core structure, and a secondary transistor connected in series with the secondary winding. One or more windings are shaped near core stack gaps to reduce core and winding losses. The inductor cell includes an inductor winding extending around the inductor core structure to provide the inductor, and the capacitor. The inductor cell is arranged in the stack structure with the transformer cells to magnetically couple the transformer primary windings, the inductor winding and the transformer secondary windings in a single magnetic circuit to cancel cell to cell flux.