The augmentation of renewable energy and distributed power source in the electric grid making the reliable operation of the grid very challenging. Solid state Transformer which power electronics converter which has characteristics that is not possessed by conventional transformer like availability of DC-port, current limit, can be used with different frequency at input and output, voltage sag compensation, better power quality, reduced size and weight because of high frequency transformer, current regulation etc. these all characteristics makes SST suitable for dc micro grid for new micro grid architecture. Three phase DAB is most suited for high power. Three phase converter is preferred in the intermediate stage of Solid state transformer due to its high full load efficiency, less RMS current, better transformer utilization factor, reduced filter and volume. The aim of this paper to analyze the performance of YD configuration using optimal harmonic number. The detailed analysis, modelling, simulation is presented with optimal number of Fourier based harmonic number. Performance analysis of the behavior of the circuit is compared with different harmonic number.