For the high-voltage level photovoltaic energy storage system, the front-end DC/DC converter is often composed of multi-channel parallel flying capacitor Boost converter (FCBC). In order to further effectively reduce the size of the inductor and improve the power density of the converter, magnetic integration technology is introduced into multi-channel parallel FCBC. Due to the characteristics of photovoltaic modules, the coupled inductor needs to meet different operating conditions. The paper focuses on the working state of the FCBC under different operating conditions and derives the requirements for the coupled inductor parameters. Finally, a three-phase FCBC simulation circuit model is built in PLECS. The simulation results verify that the coupled inductor can accommodate diverse operating conditions, reduce current ripple and improve the steady-state performance of the converter effectively.