Research On Diode-clamped PWM Three-level Inverter

Recent years, multilevel inverter has been widely used in power electronics, there is more and more study on its control strategies and the topology of its power circuit. In comparison to two-level inverter, it has some advantages as following: l.Mutillevel inverter reduce the di/dt and the dv/dt on switches;2.At a same frequency, a multilevel inverter's output has a better waveform than that of a two-level one;3.Mutillevel inverter can have higher voltage with the increasing of the number of its levels.It also have its disadvantages as following: l.Mutillevel inverter's control strategies are more complicated than that of a two-level inverter;2.Current control is more difficult in a multilevel inverter;3.Some new problems arises like the fluctuations of the neutral-point.This thesis is concentrated on SVPWM modulation strategy used in three-level inverter. Three basic control strategies of three-level inverter are analyzed. MATLAB simulink is used to simulate SPWM and SVPWM modulation strategies in three-level inverter, and then the hardware and software of a three-level inverter based on IGBT are introduced.A arithmetic is applied to compensate the THD of inverter output result from the fluctuations of the neutral-point, and then conformed with simulation in simulink.Some waveforms from simulation and from experimentations are presented At the end of this thesis.