Design of single-stage buck and boost converters for photovoltaic inverter applications

In conventional inverters, implementation of a transformer greatly enhances the Total Harmonic Distortion (THD) which is counted to have a negative impact on the inverter output. In order to overcome this limitation, transformer can be replaced by buck and boost converters thereby making a transformer-less inverter which will greatly reduce the THD and enhance the efficiency. In this paper, the design of a single stage buck and boost converters has been presented for photovoltaic inverter applications. The proposed design employs a single-stage switch mode buck converter and a single-stage switch mode boost converter. The converters are so designed that the boost converter provides an output voltage of 312V DC from 24V PV array while the buck converter provides an output voltage of 7.07V pulsated DC from 312V AC grid. The designed buck and boost converters are then employed to run a single-phase full-bridge inverter. The circuit is simulated using the PSIM software. The simulation results show that the designed buck and boost converters can be used to replace transformers from conventional inverter circuit to make low-THD, highly efficient and cost effective transformer-less inverter topology.