This chapter describes a generalized approach to modeling modular multiport power converters. These converters use half-bridge or full-bridge rectifiers or inverters connected to different ports of a multi-winding transformer and linked to various power transfer impedance blocks. Depending on the user’s performance requirements, optimization might focus on different aspects such as minimizing conduction losses, maximizing zero-voltage switching (ZVS) events, or reducing overall switching network losses. Achieving this requires a detailed and comprehensive model of all bridge currents, including their relationships with control variables such as switching frequency, phase shift angles, and duty cycles of the bridge voltages. Since phase shift and duty ratio values can vary in different ascending or descending sequences, modeling multiport converters in the time domain can become mode-dependent and computationally complex. Therefore, this chapter presents a frequency domain approach that includes higher order harmonics inclusive modeling. This method helps to derive the current waveforms and formulate the loss objective functions and soft-switching constraints for the various full-bridge ports in a unified method.