Parasitic Component Small-Signal Modeling and Control of a Practical CLLC Resonant Converter

Ashwin Chandwani, Ayan Mallik

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


This article presents a comprehensive characterization of an asymmetric resonant CLLC dc/dc converter plant transfer function obtained using a generalized harmonic approximation (GHA)-based small-signal modeling approach. The effect of circuit parasitic components is comprehensively considered while deriving this model, and a quantified comparison of the resultant plant frequency response with a conventional first harmonic approximation (FHA)-based model is presented, which provides the designer insightful findings to design a robust and noise immune closed-loop compensator. Furthermore, a thorough explanation of a sliding mode control (SMC) along with detailed parameterization of the controller coefficients is provided by analyzing the system's dynamic behavior and comparing the response with a conventional proportional-integral (PI)-based controller. In addition to the objective of designing a robust SMC controller, a phase shift-based secondary side modulation is introduced, which facilitates a significant reduction in the secondary side switching losses, thus enhancing the steady-state efficiency of the overall system. To validate and benchmark the open-loop plant response and controller dynamics, detailed steady-state results are elucidated for a 400-28- and 400-24-V voltage conversion at a rated load of 1 kW, with a resonant frequency of 500 kHz. Furthermore, a comprehensive experimental comparison between the proposed hybrid control scheme and the conventional PI controller is shown for two dynamic load changes corresponding to 10%-90% load step-up and 90%-10% load step-down. Quantification of dynamic response portrays a settling time reduction of 46.4% and an over/undershoot reduction of 33%, thus validating the robustness of the proposed control scheme.

Original languageEnglish (US)
Pages (from-to)1477-1495
Number of pages19
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
Issue number2
StatePublished - Apr 1 2023


  • DC-DC power converters
  • frequency modulation
  • resonant converter
  • sliding mode control (SMC)

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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