Shared-Core Resonant Inductor Layout for LLC Current Balancing
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Solution Overview
Problem
Current three-phase LLC power converters face efficiency issues and potential failure due to current imbalances caused by component value tolerances.
Innovation Solution
A multi-phase power supply circuit is designed with a first voltage converter stage, a resonant choke stage, and a transformer assembly. The circuit includes a pair of voltage inputs and outputs, resonant inductors wound around a magnetic core, and a transformer assembly with primary and secondary coil assemblies to balance currents and reduce common mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional three-phase LLC power converters are used with separate inductors for each phase, then the converter can operate with standard component tolerances, but current imbalance occurs among phases leading to reduced efficiency and potential failure
Solution Approach 1:
The patent combines multiple resonant inductors into a single shared magnetic core structure with multiple legs. Each phase winding is wound around different legs of the same magnetic core, creating a unified inductor assembly that provides magnetic coupling between phases. This merging approach ensures that all phases share common magnetic flux paths, automatically balancing currents even when component tolerances vary, thereby improving both reliability and efficiency.
2Ease of manufacture
If separate inductors are used for each phase to simplify manufacturing, then device complexity is reduced, but current imbalance circulating among primary currents occurs
Solution Approach 1:
The patent merges multiple inductor functions into a single integrated magnetic core assembly with multiple legs. Instead of manufacturing and assembling separate inductors for each phase, the design uses one unified core structure where multiple windings are positioned on different legs. This approach maintains manufacturing simplicity while eliminating current imbalance issues through shared magnetic flux paths.
Solution Approach 2:
The shared magnetic core creates equipotential magnetic flux paths that are common to all phases. By providing identical magnetic reluctance paths for each phase through the unified core structure, the patent ensures that magnetic flux distribution is balanced across all phases, preventing current imbalance even when winding tolerances differ.
3Loss of energy
If component value tolerances are tightly controlled to prevent current imbalance, then current balance among phases is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent eliminates the need for tight component tolerance control by merging inductors into a shared magnetic core structure. The unified core provides common magnetic flux paths that naturally balance currents across phases regardless of variations in winding parameters. This design approach shifts from relying on precise component matching to relying on structural symmetry, significantly relaxing manufacturing precision requirements.
Solution Approach 2:
The patent converts the potential harm of component tolerance variations into a benefit by using a shared magnetic core. The magnetic coupling in the unified core structure automatically compensates for component variations through flux redistribution, turning what would be a source of current imbalance into a self-correcting mechanism that enhances current balance.
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
The proposed solution effectively balances currents among phases, enhancing the efficiency of the three-phase LLC power converters and preventing potential failures by mitigating the effects of component value tolerances.
Implementation Method 1
The transformer assembly comprises a plurality of primary coil assemblies and a plurality of secondary coil assemblies
Implementation Method 2
the first and second resonant inductors are wound about a first leg of a first magnetic core
Data Source
AI summary
A multi-phase power supply circuit comprises a first voltage converter stage, a resonant choke stage, and a transformer assembly. The resonant choke stage comprises a first and second resonant inductors electrically coupled with first and second voltage outputs of the first voltage converter stage. The transformer assembly comprises primary and secondary coil assemblies. Each primary coil assembly comprises first and second primary windings. The first primary winding comprises a first node electrically coupled with the resonant choke stage and a second node. The second primary winding comprises a first node and a second node electrically coupled with the resonant choke stage. The second nodes of the first primary windings are electrically coupled together, the first nodes of the second primary windings are electrically coupled together, and the first and second resonant inductors are wound about a first leg of a first magnetic core.