الفهرس | Only 14 pages are availabe for public view |
Abstract In recent vears. industrv has begun to demand higher power equipment. which now reaches the megawatt level. Controlled ac drives in the megawatt range an? usually connected to the medium-voltage network. Today. it is hard to connect ~l single power semiconductor switch directly to medium-voltage grids. For these reasons, a new family of multilcvel inverters has emerged as a solution for working with higher voltage levels. In the last fc\\ years. interest in multi-phase multi-level inverter technology has increased due to the benefits of using more than three phases in drive applications. Most of the variable-speed electric drives use three phase machines. Nevertheless. since variable-speed ac drives include a power electronic converter. the number of machine phases can be higher than three. Major advantages of using a multi phase machine instead of a standard three-phase one are: Improved reliability and increased fault tolerance. greater efficiency, higher torque density and reduced torque pulsations. lower per phase ]1O\\er handling requirements. enhanced modularity. and improved noise characteristics. The work in this dissertation is divided into the following major parts: |