A Reduced Capacitance H-9 Five-Level Switched Boost Capacitor Transformerless Inverter

Transformerless switched capacitor-based multi-level inverters are well-known for their applications in industrial and renewable energy systems. The primary features of a switched capacitor-based transformerless inverter should be minimizing leakage current for safety and minimizing ripple current for efficiency and reliability. This article proposes a new single-stage, single-phase, five-level H-9-based transformerless inverter for standalone PV systems. This H-9 inverter, utilizes nine switches to produce the desired output voltage levels. It achieves boost functionalities by combining the switched capacitor (SC) unit with the switched boost (SB) unit in a single design. This topology effectively mitigates the leakage current by virtually grounding the load terminal through the filter capacitor. Furthermore, the ripple current of the capacitors in the switched-capacitor unit is minimized, and it is inherently balanced. To this end, the feasibility of utilizing the modulation technique for control is demonstrated, and the relevant results are experimentally validated using a laboratory prototype of the proposed converter.