DC Bias Treatment of Hybrid Type Transformer Based on Magnetic Flux Modulation Mechanism

According to the incomplete technical features of the traditional low-frequency transformer (LFT) and the existing power electronic transformer (PET), especially in terms of the function, the voltage level, and the cost, the core flux modulation of the hybrid transformer was achieved through the establishment of auxiliary windings combined with connection of the power electronic converter (PEC). For the hybrid transformer, a three-port converter topology is proposed and the strategy applicable for the dc bias compensation by connecting the converter is presented. By utilizing the dc modulation magnetic flux, the dc bias problem could be directionally compensated. The exciting current could be improved significantly and maintained at a steady state. The method proposed does not change the connection of the transformer external circuit and does not increase the peripheral device of the transformer, which provides a new way to solve the problems of magnetic state fluctuation and excitation current distortion.