Minimization of Common Mode Voltage and Capacitor Voltage Unbalance of 3-Phase 4-Wire 3-Level NPC inverter using 4D-SVM

This paper elucidates the implementation of Four-dimensional Space Vector Modulation (4D-SVM) for reduction of Common Mode Voltage (CMV) and Capacitor Voltage Unbalance (CVU) of 3-phase 4-wire 3-level Neutral Point Clamped inverter (3L-NPCI). CMV and CVU are major drawbacks of neutral point clamped inverter circuit; It leads to affect the performance of inverter in terms of bearing failure, unequal voltage stress across various switching devices, the magnitude of load current increases, increases in total harmonic distortion (THD), tripping of ground fault relays and malfunction of various sensitive electronics and control unit. The 4D-SVM algorithm is developed to reduce the CMV and CVU; with help of the nearest state vector (NSV) control method CMV range is reduced and by proper utilization of large and small vector capacitor voltage unbalance is minimized. 4D-SVM for 3-phase 4-wire 3-level includes 81 switching state vectors with a non-redundant switching concept. This algorithm is implemented without using any trigonometric equations, lookup tables, and angle determinations. This proposed system provides a comprehensive analysis of 4D-SVM for reduction of CMV range and CVU for the 3L-NPCI system. The minimization of CMV and CVU is achieved using MatLab-Simulink and FPGA processor for simulation and experimental results respectively.