Transformerless Photovoltaic Inverter Based on Interleaving High-Frequency Legs Having Bidirectional Capability

A novel bidirectional transformerless photovoltaic (PV) inverter based on the high-frequency leg (HFL) technique is proposed which can work on discontinuous current mode/continuous current mode having greatly enhanced reliability. With the high-frequency leg, the smooth ac current is achieved as the higher equivalent switching frequency can reduce the inductor current ripple decreasing the passive components' volume. There is no dead time issue which can push the duty cycle to the theoretical limit and fully transfer the energy to grid through total pulse width modulation. And the capacity of the PV inverter can be expanded easily by increasing the number of high-frequency legs. Additionally, the proposed topology can work under the rectifier mode having the bidirectional power capability, which is attractive for the PV application. In the end, the experimental results of 8-kW laboratory prototype have verified the feasibility and effectiveness of the proposed transformerless PV inverter under standalone mode.