Development of a High Frequency/Power Three-Port SST Suitable for Solar PV/Battery Interface

In this paper, a three-port Solid State Transformer (SST) is proposed to integrate solar PV and battery in a grid-tie arrangement. Unlike other SSTs, the proposed system has three active ports that are connected via H-bridge inverters allowing bidirectional power flow. Each port is galvanically isolated and power sharing action is achieved by a single high frequency transformer. Different power flow profiles can easily be achieved. The system offers reduced size, weight and cost. However, the transformer design and power control is more complicated in terms of parasitic capacitance, leakage inductance, winding placement and three-way power control. The transformer design steps, control structure, design process, simulation and experimental results are provided for a 100 kW SST system.