Loss-Optimal Modulation for an MMC-Based Triple-Active-Bridge Topology

This paper presents a loss-optimal modulation strategy for an MMC-based triple-active-bridge (TAB) converter that guarantees zero-voltage switching (ZVS). A switching pattern that blends penta phase-shift (PPS) and pulse-amplitude control (PAC) is proposed, and a generalized harmonic approximation (GHA)-based optimization is formulated to minimize total losses using device-calibrated switching and conduction loss models under power-balance and ZVS constraints. The optimization is solved offline over a grid spanning the operating space (power setpoints and dc-link voltages), and the resulting angles are stored in look-up tables for online deployment. Simulations demonstrate up to 44 % lower total losses than Phase-Shift Modulation and PPS, as well as lower conduction losses than PAC. In addition, the method expands the feasible operating region of the converter to power points that are not supported by PAC.