H6‐type transformerless single‐phase inverter for grid‐tied photovoltaic system

Abstract

There has been an increasing interest in transformerless inverter for grid-tied photovoltaic (PV) system because of the benefits of lower cost, smaller volume as well as higher efficiency compared with the ones with transformer. However, one of the technical challenges of the transformerless inverter is the safety issue of leakage current which needs to be addressed carefully. In addition, according to the international regulations, transformerless inverter should be capable of handling a certain amount of reactive power. In this study, a new H6-type transformerless inverter for grid-tied PV system is proposed that can eliminate the threat of leakage current. The proposed topology has also the capability to inject reactive power into the utility grid. Three-level output voltage employing unipolar sinusoidal pulsewidth modulation can be achieved with the proposed topology. The proposed topology structure and detail operation principle with reactive power control are investigated. The relationship among the existing topologies and their reactive power control capability are also discussed. The proposed topology is simulated in MATLAB/Simulink software to initially verify the accuracy of theoretical explanations. Finally, a universal prototype rated 1 kW has been built and tested. The experimental results validate the theoretical analysis and simulation results.

Transformerless Step-Up Inverter Based On Switched-Capacitor Converter Technology

“…The static gain for the complete circuit, i.e., after the integration between VSI and SCC, is obtained multiplying the index modulation (M) by the static gain provided by (4). Thus, the static gain for the proposed converter is: Fig.…”

“…In recent years voltage source inverters (VSIs) have been used in a wide range of applications associated with, for instance, renewable energy sources, distributed generation systems, uninterruptible power supply (UPS), electric and hybrid vehicles and smart-grids [1]- [4]. In the majority of cases VSI topologies are employed as step-down inverters (half-bridge, full-bridge, etc.…”

New Asymmetric 21-Level Inverter With Reduced Number of Switches

“…The most widely used PWM techniques for multilevel inverters are the carrier based PWM techniques (Rahim et al 2010;Jayabalan et al 2017), selective harmonic elimination PWM (SHE-PWM) techniques Zhang et al (2009) and the space vector based PWM techniques Vafakhah et al (2010). Different topologies of transformer with less inverter are proposed to improve the efficiency and reduce current leakage (Thiyagarajan et al 2016;Li et al 2015;Islam et al 2015). Lately, different topologies of multilevel inverters with reduced components have been developed (Karasani et al 2016;Alishah et al 2014;Samadaei et al 2016;Babaei et al 2014).…”

Analysis of the Robustness of Transformerless PV Inverter Topologies to the Choice of Power Devices

“…The obtained results show that HERIC topology results in a higher efficiency (96.05 %) and the lowest leakage current corresponds to HBZVR-D (42.7 mA). A 1 kW prototype is also employed in [20] for comparison purposes of three variants of H6 topology. The results show that leakage currents are in the range 19.6 − 24.5 mA rms and the range of obtained European Efficiencies is 97.22 − 97.39 %.…”