Neutral Point Grounding Configuration Effects on Voltage Balance in a Three-Phase IPOS LCC Resonant Converter

Three-phase input-parallel-output-series (IPOS) LCC resonant converters are widely adopted in high-frequency, high-power applications due to their superior power density and low output ripple characteristics. Nevertheless, inherent output voltage imbalance induced by resonant parameter asymmetry poses critical challenges, including elevated voltage stress on components, increased system costs, and compromised operational stability. This study systematically investigates the pivotal role of neutral point grounding configuration in modulating voltage distribution across parallel modules in a three-phase IPOS-type LCC resonant converter. Through fundamental component analysis, we establish a simplified yet accurate mathematical model that quantitatively characterizes the nonlinear relationship between resonant parameters and output voltage deviation. Using the proposed mathematical model combined with MATLAB/ Simulink simulation and prototype experiments, this paper investigates the neutral grounding configuration issue of the converter in this study under full-load conditions. Close correspondence is observed between theoretical predictions and both simulation and experimental results. Ultimately, the analysis demonstrates that, in the absence of any special modulation techniques, grounding the neutral point in this paper is more beneficial for voltage balance, thereby reducing component costs, enhancing circuit safety and stability, and promoting a more uniform thermal distribution across the components. The proposed approach in this paper offers a feasible path for the optimization of similar multi-module resonant converter systems.