Harmonic Distortion Reduction of Transformerless Inverter’s Output Voltage Using 5-Level Single-Phase Inverter and LCL Filter

Transformerless inverters have harmonic distortions present in their output voltage due to power electronics switching. Total Harmonic Distortions present in the output voltage can be minimized by using 5-level Cascaded H-bridge Inverter instead of 3-level or 2-level H-bridge Inverter. To maintain the IEEE Harmonic Standards, an LCL filter is proposed which can be used between the inverter and the load. Simulation of two types of inverter with and without a filter and with different kinds of switching are done. Comparing the result, 5-level cascaded H-bridge with proposed LCL filter combination is proposed for having the lowest harmonic distortion. Simulation results prove that the proposed inverter filter topology has significantly reduced Total Harmonic Distortion in the output Voltage. This will help to secure the load elements, increase their lifetime and reduce the power loss caused by unusual harmonics and get a nearly pure sinusoidal AC Voltage output at the output terminal of transformerless inverter and across the load.