An Improved GHA-Enabled Steady State Model-Derived Semiconductor Loss Optimization for a Three-Port C3L3 Resonant Converter

This paper presents a new modeling approach for a multi-port resonant converter that accounts for the non-approximated effects of all switching harmonics on determination of the natures of port currents and power transfer dynamics. As proved in this work, resonant converter modeling performed with resistive approximation of the AC equivalent impedance introduces $\geq 10 \%$ error in port current rms, peak and switching instant values estimation. This error further propagates in semiconductor loss calculation process yielding incorrect losses during converter operation and inaccuracies in optimum control variables determination required for generating desired power and voltage at the output ports. This error is rectified using a reconceived modeling approach called Improved Generalized Harmonic Approximation (I-GHA). This modeling approach is compared with the simulation results and the contemporary state-of-the-art approaches such as Generalized Harmonic Approximation (GHA) and First Harmonic Approximation (FHA) - both of which use equivalent resistance approximation. A semiconductor loss model developed using this redefined approach serves as the basis for categorical as well as total semiconductor loss optimization. To benchmark the converter performance vis-à-vis the developed analytical model, an all-GaN based 2 kW three-port C3L3 prototype is developed for a resonant frequency of 490 kHz. Experimental validations for various loading conditions are presented for a wide-gain three-port power conversion (400V to 500-600V and 22-28V) at corner conditions to verify the derived modeling methodology.