NewDirect TorqueControl SchemeforInduction Motors

Inthis papera novel controller based on Direct Torque Control ispresented. Thiscontroller hasbeen designed tobeapplied inthecontrol ofinduction motorsfedwithathree-level Voltage Source Inverter (VSI). Thistypeofinverter hasseveral advantages overthestandard two-level VSI,suchas a greater numberoflevels intheoutputvoltage waveforms, lessharmonic distortion andlowerswitching frequencies. Inthe new controller thehysteresis regulators andlook-up table arenotused, andinstead, the torque andstator flux errorsareusedtogether withthemotorspeed togenerate areference voltage vector that canbesynthesized using different techniques afterwards. Experimental results ofthenovel system are presented andcompared withthose obtained forClassical DTC systemwhenemploying two-level VSI. Thenew controller isshown toreduce theripple inthetorque andflux responses.Lowercurrent distortion andswitching frequency ofthesemiconductor devices arealso obtained inthe new systempresented.