Coupled-Inductor Bidirectional CLLC Circuit for Magnetic Integration
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Solution Overview
Problem
Existing CLLC resonant converters have inefficiencies in magnetic integration, leading to large volume and weight due to separate magnetic elements, and existing integration methods either lack precise control over leakage inductance or require customized magnetic core designs, limiting flexibility and application.
Innovation Solution
A bidirectional CLLC circuit with a coupled inductor replaces separate resonant inductors with a single coupled resonant inductor and integrates them into a transformer, allowing for flexible selection of inductance values to maintain equivalent resonant frequency and gain characteristics, reducing the number and volume of magnetic elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If separate magnetic elements (two resonant inductors and one transformer) are used in CLLC converter, then the converter can achieve high efficiency and high power density, but the volume and weight of magnetic elements occupy relatively large space
Solution Approach 1:
The patent merges the primary resonant inductor and secondary resonant inductor into a single coupled inductor with primary and secondary windings. This integration reduces the number of separate magnetic elements from three (two inductors plus transformer) to two (coupled inductor plus transformer), directly addressing the volume reduction goal while preserving the resonant circuit functionality through the coupled inductor's dual-winding structure.
2Device complexity
If existing magnetic integration technique increases leakage inductance of transformer to integrate resonant inductors, then integration is achieved, but conduction loss of transformer coils increases
Solution Approach 1:
Instead of increasing leakage inductance within the transformer, the patent segments the resonant inductor function from the transformer by introducing a separate coupled inductor. This segmentation allows the transformer to maintain low leakage inductance for efficient power transfer while the coupled inductor provides the necessary resonant inductance, thereby reducing conduction losses in transformer coils.
3Manufacturing precision
If leakage inductance is increased by adjusting magnetic core structure to provide additional pathway for leakage flux, then inductance amount is precisely controlled, but customized design on magnetic structure is required
Solution Approach 1:
The patent employs a universal coupled inductor structure with primary and secondary windings that can be manufactured using standard magnetic cores and winding techniques. This multi-functional component simultaneously provides resonant inductance and coupling functionality without requiring customized magnetic core structures, making it adaptable to various CLLC converter designs while maintaining ease of manufacture.
4Device complexity
If turn ratio of transformer is changed to integrate one resonant inductor, then number of magnetic elements is reduced, but flexible selection of inductance values is limited
Solution Approach 1:
The coupled inductor provides dynamic adjustability of inductance values through its coupling coefficient and winding configurations. By varying the coupling between primary and secondary windings or adjusting the number of turns in each winding, the resonant inductance can be dynamically tuned to match different application requirements, offering greater flexibility compared to fixed transformer turn ratio approaches.
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 reduces the volume and number of magnetic elements, optimizes power density, and allows for standardized magnetic core usage without customized designs, achieving efficient energy transfer while maintaining circuit properties.
Implementation Method 1
a bidirectional CLLC circuit with a coupled inductor... allows for flexible selection of inductance values to maintain equivalent resonant frequency and gain characteristics, reducing the number and volume of magnetic elements
Data Source
AI summary
Related to is a bidirectional CLLC circuit with a coupled inductor, which is associated with a circuit topology and operation control of a bidirectional CLLC resonant converter. Provided is a structure of a bidirectional CLLC resonant circuit with a coupled inductor, including a primary side bridge, a secondary side bridge, a primary side resonant capacitor, a secondary side resonant capacitor, a coupled resonant inductor, and a transformer. Compared with a structure of a conventional bidirectional CLLC resonant circuit, two separate resonant inductors located at a primary side and a secondary side in an original resonant cavity are replaced with one coupled resonant inductor in the circuit; the coupled resonant inductor has opposite dotted terminals with the transformer, and a primary side and a secondary side of the coupled resonant inductor are respectively in serial connection with a primary side and a secondary side of the transformer.