Interleaved LLC Converter Current Equalizing Winding
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Solution Overview
Problem
Interleaved LLC converters face challenges with current unbalance due to parameter tolerances in resonant cavities, leading to uneven load conditions and potential damage, especially in high power and high current applications, where accurate determination of resonant parameters is difficult.
Innovation Solution
An interleaved LLC converter with current sharing, comprising an interleaved LLC circuit with coupled inductors and a closed magnetic core, where windings are inversely coupled and connected to achieve balanced current distribution, utilizing an output capacitor to stabilize the output terminals, and controlling resonant parameter tolerances within 10% to ensure accurate current sharing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If interleaved LLC circuits are used to reduce current ripple, then output current quality is improved, but current unbalance between circuits occurs due to parameter tolerances
Solution Approach 1:
A current equalizing converter is introduced as an intermediary device between the interleaved LLC circuits and the output. This converter actively monitors and adjusts the current distribution among parallel LLC circuits, compensating for parameter tolerances and preventing current unbalance while maintaining the low current ripple benefits of interleaved topology.
Solution Approach 2:
The current equalizing converter implements feedback control by continuously monitoring the output currents of parallel LLC circuits and adjusting their operation accordingly. This feedback mechanism detects current unbalance caused by parameter tolerances and dynamically compensates to maintain equal current sharing, resolving the contradiction between improved current quality and reliability.
2Reliability
If resonant parameters are tightly controlled to achieve current balance, then current sharing is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The current equalizing converter enables the interleaved LLC system to self-correct current unbalance automatically. Instead of requiring precise manual control of resonant parameters during manufacturing, the system uses the equalizing converter to autonomously adjust and balance current distribution, reducing manufacturing complexity while maintaining reliable current sharing.
Solution Approach 2:
The current equalizing converter dynamically adjusts operating parameters of the interleaved LLC circuits to compensate for fixed parameter tolerances in resonant components. By changing controllable parameters (such as switching timing or duty cycle) rather than requiring precise fixed parameters, the system achieves current balance without increasing manufacturing complexity.
3Manufacturing precision
If multiple capacitors are used in parallel to absorb current ripple, then current ripple is reduced, but device complexity and cost increase
Solution Approach 1:
The current equalizing converter serves as an intermediary active device that replaces the need for multiple parallel capacitors. By actively managing current distribution among interleaved LLC circuits, the converter achieves superior current ripple reduction with a single integrated device, reducing both device complexity and cost compared to passive capacitor-based solutions.
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 solution effectively balances current distribution between LLC circuits, reducing the risk of overloading or damage, and achieving accurate current sharing even with ±5% component tolerance, thereby enhancing the reliability and efficiency of high power applications.
Implementation Method 1
a first half of the plurality of windings surround a magnetic core in a first direction, and a second half of the plurality of windings surround the magnetic core in a second direction; each of the plurality of windings has the same inductance, and the first half of the plurality of windings are inversely coupled with the second half of the plurality of windings
Implementation Method 2
utilizing an output capacitor to stabilize the output terminals
Implementation Method 3
the parameters of the two resonant cavities may not be completely consistent with each other in practical application
Data Source
AI summary
The present invention discloses an interleaved LLC convertor with current sharing. The interleaved LLC convertor with current sharing comprises: an interleaved LLC circuit, consisting of an even number of LLC circuits connected in parallel; and a plurality of windings with the same quantity as that of the LLC circuits, wherein all first polarization terminals from each of LLC circuits at its DC output side together constitute a first output terminal; all first terminals from each of the windings together constitute a second output terminal; a first half of the plurality of windings surround a magnetic core in a first direction, and a second half of the plurality of windings surround the magnetic core in a second direction; each of the plurality of windings has the same inductance, and the first half of the plurality of windings are inversely coupled with the second half of the plurality of windings; and the second polarization terminal of each LLC circuit at its DC output side connects to a second terminal of one of the windings.