Multi-frequency Modulation Based Cascaded Power Electronic Transformer

For medium and high voltage distribution networks, the cascade structures have been employed on the high voltage side of power electronic transformer, witch lead to increased hardware costs and larger system volume of PET. To overcome these limitations, this paper introduces a novel cascaded PET topology. The proposed topology incorporates the concept of multi-frequency modulation to achieve hardware multiplexing, resulting in a significant reduction in the number of power switching devices and high-frequency transformer utilized. The paper begins by describing the working principle and presenting the mathematical model of the new topology. Subsequently, the control strategy for each power conversion link is discussed in detail. Finally, the correctness and effectiveness of both the PET topology and the corresponding control strategy proposed in this paper are rigorously verified through simulation.