Venkatraman.E, Raja.P
The transformerless inverter for grid connected photovoltaic system is proposed in this paper with the intent to improve the reliability and reduce the common-mode leakage current.the proposed inverter incorporates two coupled inductors along with series connected switch on ac side that operate alternately in positive and negative half period of grid. This inverter eliminates shoot through problem which is common in NPC topologies,resulting improved system reliability. Therefore ,dead time at both switching frequency commutations and grid current zero crossing instants are not required. The coupled inductor along with series connected switch will not allow current to flow through anti-parallel diode of switches, avoding reverse recovery issues.switch such as cool MOSFETs now can be used in the proposed inverter, which increases the converter efficiency. In addition to high reliability, the proposed inverter maintains common-mode voltage at a constant level resulting low common-mode leakage current. Derivation of the full-bridge NPC inverter from existing single-phase transformer less H6 topology is presented. Other alternative full-bridge NPC inverter topology is also illustrated. The principle of operation and leakage current analysis of proposed NPC inverter are described.In order to communicate and synchronize H6 bridge inverter fed Grid-connected photovoltaic system without transformer is implemented by using MATLAB/SIMULINK.
single-phase transformer less H6 topology,MOSFETS switch,PV system.