Common-Ground-Type Inverter With Dynamic Boosting and Reactive Compensation for Grid

Given the lack of transformer isolation in operational non-isolated photovoltaic inverters, common mode leakage currents are known to exist within the stray capacitance of the photovoltaic array, leading to electromagnetic interference and safety concerns for the entire system. This article introduces a novel solution: the common ground non-isolated multilevel PV inverter. This innovative design is built upon the Boost circuit and incorporates a switched capacitor network to connect the negative terminal of the dc side to the neutral point of the ac side. The primary objective of this configuration is to theoretically eliminate common mode leakage currents originating from the stray capacitor, effectively grounding them. Furthermore, this inverter eliminates the necessity of a cascade boost unit, thereby significantly reducing its dependency on the voltage level on the dc side. Additionally, it adopts a feed-forward space vector modulation strategy, enabling the output variable to be decoupled from the capacitor oscillation voltage. To validate the effectiveness and practicality of this proposed scheme, a 220 V/1 kW experimental platform was constructed and tested in this article.