Reliable and optimal design of variable inductor integrated LLC converter

The variable inductor integrated LLC (VI‐LLC) converter is able to operate at constant switching frequency and avoid wide variable frequency range and thus emerged in recent years. However, VI‐LLC converter suffers two reliability problems. First, coupling between the main winding and the control wi...

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Bibliographic Details
Published in:International journal of circuit theory and applications 2024-09, Vol.52 (9), p.4207-4233
Main Authors: Wu, Mingtao, Du, Guiping, Wang, Xueyi, Chen, Yu
Format: Article
Language:English
Subjects:
Coupling
Design engineering
design methodology
Design optimization
Design parameters
Frequency ranges
Inductors
LLC converter
parameter fluctuation
Reliability
variable inductor
Voltage gain
Winding
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Summary:The variable inductor integrated LLC (VI‐LLC) converter is able to operate at constant switching frequency and avoid wide variable frequency range and thus emerged in recent years. However, VI‐LLC converter suffers two reliability problems. First, coupling between the main winding and the control winding of variable inductor (VI) causes negative effects on the converter, which are few considered in the literature. Second, parameter fluctuation (PF) of resonant elements has negative effects on operation and gain reliability of VI‐LLC converter, causing unreliable operation and voltage gain deviation. To solve the above problems, in this paper, a reliable and optimal design methodology of VI‐LLC converter is proposed. First, the coupling effects of VI are introduced and analyzed, with a coupling index proposed to quantify and reduce the coupling effects. Then, negative effects on VI‐LLC converter caused by PF are visualized and eliminated with the filtered parameter space and the redetermined variation range of VI. Based on the above consideration, a reliable final parameter space considering PF effects and the coupling problem is established. Finally, the efficiency space referring to the final parameter space is established based on the loss model of VI‐LLC converter to determine the optimal design candidate. Experimentation has shown a good agreement with theory and proven validity of the proposed design methodology. A optimal design methodology of variable inductor (VI) integrated LLC converters that fully considering parameter fluctuation (PF) effects of resonant elements and coupling effects of VI is proposed. The PF effects are revealed and eliminated, and the coupling effects are qualified and reduced to strengthen reliability of the converter.
ISSN:0098-9886
1097-007X
DOI:10.1002/cta.3973