A Full-Iteration Optimal Design Methodology of CLLC Converter With Minimized RMS Current

With the wide application of the
CLLC
converters in bidirectional electric vehicle chargers, it becomes more important to improve their performance through proper parameter design. Compared with the frequency domain model, the time-domain model can significantly improve the accuracy of converter design. However, the currently generalized operation mode analysis method requires complicated operating mode judgment and solving systems of transcendental equations, which limits its practicality. To address this issue, a discrete event-driven piecewise analytic model (DEPAM) of
CLLC
converter is proposed in this article. DEPAM obtains the transient and steady-state waveforms without the need for operating mode judgment and solving transcendental equations. Relying on DEPAM, a design methodology of the
CLLC
converter is introduced in this article, which applies the lookup table method to the normalized parameters and achieves a complete traversal of all possible parameter combinations of the
CLLC
converter. This traversal considers gain range, soft-switching, capacitor voltage stress, and rms current simultaneously. Finally, the design methodology is demonstrated through a 1 kW prototype with 98.8% peak efficiency.