Performance Investigation of Three-Stage Modular Smart Transformer with Sliding Mode Control

The Smart Transformer (ST) is an intelligent power transmission device between AC and DC grids, which facilitates the integration of renewable energy resources, electric vehicle charging stations, and energy storage batteries into the distribution grid. This paper proposes a three-stage smart transformer model comprising a Cascaded H-Bridge (CHB) rectifier for the input stage, three dual active bridge converters for the isolation stage, and a four-leg inverter for the output stage. In order to improve the dynamic performance of this model, the sliding mode control has been applied to its input and output stages, and the soft switching control has been used in the isolation stage. To investigate the performance of the ST control strategy, a series of simulations were performed under disturbances, namely, voltage drop, voltage swell, harmonics distortion, and flickers in the MATLAB environment. The obtained results confirm the robustness of the ST controller against these disturbances.