Research On Neutral Point Floating Of Three-level Inverter

The research on high voltage inverter has made a good progress with the development of power and electronic technique, computer science and control theory. High voltage motor driven by high voltage inverter can satisfy the governed speed demand during the industry processs and can also save a large amount of power energy. Nowadays this can make a good sense because the energy emergency is becoming serious.Three-level inverter is applied widely in many industry fields for its excellent performance. Through referring lots of national and native conference documents, the understanding to the current researches on three-level inverter is obtained, the profound comprehension to the feature of different PWM control strategies and control methods are acquired.The thesis first introduced the widely development of the high voltage inverter and introduced the main topologies and the control method of the high voltage inverter, deeply analyzed fundamental principle of three-level SVPWM and using MATLAB simulated the process of the pulse generation and analysed the output wave form of the inverter.Analysed the reason of neutral point waving in order to control the unbalance of the neutral point .This thesis propose a new method to control the unbalance of the neutral point based on the information of the waving voltage. The result show that the method proposed in this thesis can control the neutral point waving efficiently, whether the two capacitors connected in series have the same capacity or not.