A Mutual Inductance–Capacitance IPOS-Type Self-Balancing LLC Resonant Converter

In low-voltage-input, high-voltage-output applications, the input-parallel output-series (IPOS) LLC resonant converter experiences voltage and current imbalances due to parameter mismatches in resonant tank components. To address this issue, a self-balancing IPOS LLC resonant converter based on a shared inductance–capacitance (shared L-C) network is proposed. This topology achieves passive voltage and current self-equalization with an interconnection network of resonant inductors and capacitors between modules that does not need additional active components or complex control strategies. An analytical model based on the fundamental harmonic approximation (FHA) is developed to quantitatively assess the balancing performance, and a comparison is made with traditional structures and IPOS structures with only shared inductance. A 1.25 kW two-phase LLC resonant converter prototype is built for experimental validation. The results demonstrate that the balancing errors of the traditional structure and the shared inductance structure reach up to 25.43% and 17.63%, respectively, whereas the proposed structure significantly reduces the balancing error to only 0.43%. This study confirms that this structure provides a simple and reliable solution for voltage and current equalization in high-gain DC–DC conversion systems.