A Single-Phase Transformerless Common-Ground Type PV Inverter With Active Power Decoupling

To solve the problems of existing nonisolated PV grid-connected inverters, such as leakage current, power pulsation, and harmonic current, a single-phase common-ground-type nonisolated grid-connected inverter with power decoupling capability is proposed in this article. The integration of the traditional boost converter and the switched capacitor technology obtains the structure that the neutral point of the grid is directly connected with the negative terminal of PV array, and the leakage current is eliminated. Due to the time-sharing multiplexing of circuit components, which can achieve power decoupling and high step-up, fewer semiconductor devices are required in proposed inverter. At the same time, the improved control strategy ensures that the inverter can adapt to the voltage ripple of large decoupling capacitor. This article introduces the working principle, mode, performance, and control strategy of the novel topology in detail. Finally, the experimental prototype with rated output power of 320W verifies the superior performance of the inverter.