Research On SHE-PWM Control Technique Applied To Three-Level NPC Converter

Since it’s introduction in 1981 by A.Nabae, the three-level Neutral-point-clamped (NPC) voltage source converter has been gotten further development and widely used because of its own advantages.The applications of this technology not only include high-capacity and high-performance inverters, but also include active filtering, static VAR compensation systems, as well as applications in power conditioning systems. This dissertation researched on three-level Neutral-point-clamped (NPC) voltage source converter,each part of the main circuit and control method were detailed analysis and research. The main contents are as follows:1.The main types of three-level converter topology are introduced, and carries on the contrast analysis to the respective advantages and disadvantages, then mainly analyzes the basic rules of three-level neutral point clamped (NPC) converter working principle and the switching of each working state, and carries on the simulation experiment, so as to have a further understanding of it.2.The characteristics and switching characteristics of high power switching device IGCT are analyzed. Put the product of ABB company as the object, and model IGCT under the environment of PSIM, then carries on the single tube test, so as to verify the correctness of the model.3.To analyze the three level converter’s LCL filter, study and summarize the parameters of the design process of a variety of restrictions. At the same time, in the specific experimental conditions of the experimental simulation, to verify its accuracy.4.In order to eliminate the low harmonics generated by three-level converter which connected with power grid in the state of high power and low switching frequency. To analyze specific harmonic eliminate method (SHEPWM) principle, the previous research results are summarized, and put forward a new method, validated by experiment and simulation.