Study On Back-to-back Three-level Converter System For Induction Motor Of MW Grade

The shortage of power supply and the government's requirement of"energy-saving emission reduction"prompt the replacement of a number of high-power, in particular MW-level drive sytems. Traditional diode rectifier of the converter maked the quality of grid worse. In the medium-voltage drive system field, as three-level topology has many advantages, so the back-to-back three-level converters have been more and more put into production fields.In this dissertation, regard MW-level induction motor with back-to-back three-level converter control system as the research object, based on three-level space vector pulse width modulation (SVPWM) and phase voltage reconstruction algorithms, the following ites are studied : the flux observer of virtual grid-flux-oriented vector control PWM recitifier, the DC bus voltage fluctuations study based on small-signal model, recitifier test method, rotor flux observer and back-stepping control theory of induction motor.