Modelling and Realisation of a Three-Level PWM Inverter Using a DSP Controller to Feed an Asynchronous Machine
Multilevel inverters have seen an increasing popularity in the last few years for medium- and high-voltage applications. The most popular has been the three-level neutral clamped inverter. Multilevel inverters synthesize output voltage from more than two voltage levels. Thus, the output signal spectrum is significantly improved in comparison with the classical two-level converters. This chapter discusses modelling and control of a Neutral Point Clamped (NPC) inverter which operates with the PWM switching pattern using a DSP. The mathematical model of the NPC inverter is carried out using conversion and connection functions for an easier understanding of the system operation. Simulation results using MATLAB program are reported, and it is shown that the performances obtained for driving an asynchronous motor using this inverter are very promising. Finally, analysis of the theoretical and the experimental results is carried out in order to validate the effectiveness of the proposed control solution.