This manuscript proposes a modeling and critical analysis of multiple-inputs, multiple-outputs (MIMO) applied to a series hybrid electric vehicle (SHEV) power-train composed by coupled bidirectional dc/dc and ac/dc converters. The model outputs are obtained as linear combinations of the inputs through a steady-state gain matrix, whose elements are functions of the electrical parameters of the SHEV. The mathematical solution is validated by simulations of a load profile taken into account the mechanical power calculation obtained from the vehicle dynamics. The developed representation allows the designers a more reliable analysis of the dynamic behavior considering the state variables of the power train electrical system, which enables the design of control systems and power converters sizing.