Five-level Common Ground Type Inverter for PV Application

In renewable energy sources transformer-less grid-tied inverters are widely used due to their higher efficiency, reduced cost and size. With the absence of transformer, there exists leakage current due to PV-to-ground parasitic capacitance leads to deteriorated power quality, cause personal safety issues and electromagnetic interference (EMI). In this paper, a five-level transformer-less inverter topology is proposed to eliminates the leakage current based on the principle of switched capacitor. Besides, the proposed topology has naturally balanced voltage capability, so no dedicated control strategy/algorithm is required for balancing/regulating the flying capacitor voltages. The performance of the proposed inverter is verified by simulation results, proving the feasibility and merits of proposed inverter topology are presented. Results depicting the output voltage, load current and voltage across the auxiliary capacitor are presented for various operating conditions. Further, simulation results depicting the leakage current in the proposed, H-5 and H-6 topologies are included. Moreover, a quantitative comparison study is presented, highlighting the benefits of the proposed inverter topology regarding boosted voltage, elimination of leakage current and reduced component count.