A Specific Analysis Model of Three-level NPC Inverter fed Adjustable Speed Drive System with High Accuracy

Three-level NPC inverters are widely used in motor drive systems, especially in high voltage, large capacity applications. However, the characteristic analysis of the three-level inverter fed motor drive system is inconvenient due to its high cost and complexity. In this paper, a specific analysis model of the three-level NPC inverter fed adjustable speed drive system is developed. Key issues in the modeling are considered and discussed in detail. The developed model has been validated through the comparisons between the simulation results and the experimental measurement results, which exhibits very high accuracy such as the accuracy +/- 5% on static characteristics, +/- 10% on dynamic characteristics and +/- 20% on THD of stator currents.