Battery energy storage system with isolated single-phase matrix converter using center-tapped transformer for power decoupling capability

This paper discusses a bi-directional isolated single-phase matrix converter using center-tapped transformer, which has a power decoupling capability for battery energy storage systems for renewable energy sources such as PV and wind turbine systems. The proposed converter is comprised of a full bridge inverter, a high frequency transformer and a matrix converter in order to eliminate large DC-link smoothing capacitor. The power decoupling method employs a center-tapped transformer and a small capacitor without any additional switches, which aims to achieve high efficiency. In this paper, by harmonic analysis, the effectiveness of power decoupling capability is verified in two cases: discharging/charging modes of a battery, which need to keep output power constant from battery for a single-phase grid system. As a simulation and experimental result, the validity of the power decoupling capability is confirmed in a charging/discharging mode. In addition, the proposed power decoupling method reduces the DC bus current ripple generated by a single-phase load to 85.1% in the discharging mode of experiments.