磁 集 成 三 端 口 电 力 电 子 变 压 器 的 改 进 控 制 方 法

Aiming at the problems of large magnetic component volume, multiple power conversion units and high cost of the existing multi-port power electronic transformer (PET), this paper proposes a three-port topology and its control strategy based on magnetic integration. To reduce the volume of the magnetic component, six arm inductors and multiple high-frequency (HF) transformers in the traditional topology are simplified into three integrated transformers. The low-voltage direct current (LVDC) port can be obtained by connecting a three-phase bridge to the secondary winding of the transformer, thus saving a great number of power conversion units. To achieve multi-port power control, the DC, line-frequency and HF components of the arm voltage are used to control the power at medium-voltage DC (MVDC), medium-voltage AC (MVAC) and LVDC ports, respectively. To improve the power quality of the MVDC port, the HF component of the arm voltage is designed as a three-phase symmetrical six-step waveform, so that the current components excited by it could cancel each other in the three-phase circuit, thus the HF current ripple of the MVDC port can be eliminated. Finally, a 4 MW simulation model is established to verify the effectiveness of the proposed topology and its control strategy.