Single stage transformer less multilevel inverter for solar PV application

Abstract

The article presents a single stage transformer less multilevel inverter (SSTL-MLI) with common ground based inverter topology for grid tied PV application. It is designed with only 5 switches for 5 level generation. It uses switched capacitor approach therefore, needs single DC-source. Moreover, the topology has self voltage balancing feature, thereby no need of additional circuit. The peak current control (PCC) strategy is utilized to regulate switching pulse. MATLAB/Simulink is used to assess the proposed topology performance. It results voltage and current total harmonic distortion (THD) with values 32.49% and 1.66% respectively at the specified load at inverter output. It also satisfies IEEE 519 standard for power quality with grid current THD with value 2.12% for 20 harmonic order. The proposed system obtains maximum efficiency ($\eta$) with 98.30% value at input voltage (400V), and output power (4.72 kW). The cost function, composition with number of switch counts, DC source, weight coefficient and total standing voltage value has lowest value i.e. 16.75 in the proposed topology. Moreover, a scaled down prototype with 350 W rating is built of the proposed topology and validated under number of test condition such as change of load i.e resistive to inductive load, change of modulation index, and frequency change condition. The detailed comparative analysis is also presented in terms of switch count, TVS, MSV, efficiency, gain, cost function by comparing of number of existing topology so that the favorable feature of the proposed topology can be highlighted.