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

Ashwin Chandwani, Ayan Mallik

Research output: Contribution to journalArticlepeer-review


This paper presents a comprehensive characterization of an asymmetric resonant CLLC DC/DC converter plant transfer function obtained using 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 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. Further, a thorough explanation of a sliding mode control (SMC) along with detailed parameterization of the controller coefficients is provided by analyzing the system dynamic behavior and comparing the response with a conventional proportional integrator (PI) based controller. In addition to the objective of designing a robust SMC controller, a phase-shift-based secondary side modulation is introduced that facilitates 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 400-28V and 400-24V voltage conversion at a rated load of 1kW, with a resonant frequency of 500kHz. Further, comprehensive experimental comparison between the proposed hybrid control scheme and 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 portray 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)1
Number of pages1
JournalIEEE Journal of Emerging and Selected Topics in Power Electronics
StateAccepted/In press - 2022


  • Analytical models
  • Harmonic analysis
  • Integrated circuit modeling
  • Load modeling
  • Mathematical models
  • Topology
  • Windings

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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