Voltage Controller for 3 Level NPC-MLI Based HSVM With Grid Connected PV System

Objectives: This paper proposes an improved Neutral Point Clamped 3-Level Inverter (NPC-TLI) that is suitable for transformer-less Photovoltaic (PV) grid connected system. Methods/Analysis: The use of NPC topology guarantees the reduction of shoot-through risk and helps keep common mode voltage in check. The inverter is controlled by Hysteresis Space Vector Modulation algorithm which helps to decrease Total Harmonic Distortion (THD) factor in the output. The proposed system simulation results were verified using MATLAB/SIMULINK. Findings: Furthermore, the use of a split inductor helps to avoid the use of a transformer, hence, reducing the size, leakage current and the voltage stress in the inverter. The input of the system is derived from a PV source whose output can be synchronized with a grid connected system. Novelty/ Improvement: The use of SVVC using hexagonal hysteresis areas ensures reduced THD and improved DC link voltage balancing in the capacitors of the NPC configuration. Reduced common mode voltage, and switching losses are other added benefits of the inverter configuration.