Authors: Akshay Kumar Rathore, Senior member IEEE, and Venkata R Vakacharla, student member IEEE


The Fundamental Harmonic Approximation (FHA) analysis favored engineers by alleviating obstacles in analysis, loss computation, and optimization by reducing complex resonant converter into a mere Resistance-Inductance-Capacitance (RLC) circuit. However, to improve the power density of an X-ray machine power supply, elimination of filter inductor leaves parallel and series-parallel resonant converters with capacitive filter in output, which forces the Rear End Rectifier (RER) to draw discontinuous currents. These unprecedented discontinuous currents through resonant tanks complicate the FHA analysis, a simple and elegant approach, by forcing it to adopt computer-aided techniques and numerical methods similar to the time domain, state-space, and state-plane approaches. Therefore, all available tools, including traditional FHA, fail to model these converters with reduced complexity and labor. Addressing this issue, this paper presents a technique to restore the simplicity of FHA analysis in the case of parallel and series-parallel resonant converters terminated with capacitive filters. The authenticity, simplicity, and accuracy of the proposed technique are demonstrated through results. Further, a detailed comparison with existing modeling techniques is also provided.

voltage gain graph
Comparison of voltage gain predicted by proposed ELS circuit, with voltage gain obtained through simulation of actual LCC resonant converter

This paper is published in IEEE Transactions on Industrial Electronics

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