Switching frequency imposition and ripple reduction in DTC drivesby using a multilevel converter

摘要

A new strategy for direct torque control with imposed switchingnfrequency (DiCoIF) is proposed. This strategy was specially designed tonoperate with a multicell (flying capacitors) inverter with any number ofnlevels, which means it can also be used for standard two-levelninverters. This approach combines the well known advantages of thenmulticell. inverter with those of a direct torque controlled (DTC) basednstrategy. It is shown that the multicell topology presents enoughndegrees of freedom to control both torque and flux with very low ripplenand high dynamics on one hand, and to impose the switching frequency andnthe capacitors voltage balance on the other hand. Experimental andnsimulation results, obtained with a standard two-level inverter and withna four-level multicell inverter, are presented and discussed. Finally, ancomparative analysis either with the classical DTC and field orientedntechniques is carried out