Modulation Strategy of Cascaded Three-PMSM System Fed by a Seven-Leg Inverter

In the industrial field, the multi-motor system has experienced rapid development and found numerous applications. It is imperative to reduce system cost while maintaining excellent performance. This article introduces a novel modulation scheme designed for a cascaded multi-motor system comprising three three-phase motors and a seven-leg voltage source inverter (SL-VSI). Contrasted with the traditional setups involving triple three-phase VSI structures, this topology eliminates two inverter legs and possesses higher robustness than the classical topology setting single common leg. The proposed modulation strategy enables independent control of the three PMSMs and facilitates varied speed and torque outputs for flexible and coordinated driving. Additionally, the proposed modulator reduces the current ripple effectively. Ultimately, the experimental results validate the superiority of the proposed inverter topology and relative control method.