Analysis and simulation of a multilevel inverter converter NPC Cascade

This paper describes the control and regulation of input DC voltages of nine-level NPC voltage source inverter. The analysis and simulation of a cascade constituted by three phase´s five-level PWM rectifier-nine levels NPC voltage source inverter (VSI). In the first part, the authors present the five-level PWM rectifier. After, we present a topology of nine levels NPC VSI for then we propose a model of this inverter and the SVPWM strategy which uses eight bipolar carriers to control it. The study of this cascade shows that the input DC voltages of the inverter are not stable and not equals. To remedy to this problem, the authors propose to introduce in the cascade a clamping bridge and regulation using PI regulator. In the second part, we study speed control of the Permanent magnet synchronous machine (PMSM) by using the field oriented control. The results obtained are full of promise to use the inverter in high voltage and great power applications as electrical traction.