| Multilevel converters have drawn more and more interests in power industry. The general structure of a multilevel converter is to synthesize a sinusoidal voltage from several levels of voltages. There are three basic multilevel topologies, known as cascade multilevel converter, diode-clamping multilevel converter, and flying capacitor multilevel converter. Recently, a lot of new topologies of multilevel converters have been reported, such as, hybrid multilevel converters and modular multilevel converter (MMC).;The diode-clamping multilevel converters are widely adopted in industry applications, since the cost and size of required clamping diodes is smaller than those of floating capacitors in flying capacitor multilevel converter, or the isolation providers in cascaded multilevel converter. However, there are two main effects that limited the growth of diode-clamping multilevel converter. One is the quadratically increasing number of switching devices, especially that of clamping diodes with increasing number of output voltage levels; another is the voltage balance between the DC capacitors.;In this dissertation, a new topology of a multilevel inverter is proposed. A study on the circuit topology of a diode-clamping multilevel converter with a small number of switching devices is conducted. The modulation methods and the possibility of voltage balance control of the proposed circuit are investigated. Simulation results in MATLAB/SIMULINK are used to verify the concept. Finally, a 1kW prototype is built and experimental results are compared with the simulation results. The experimental results are in a good agreement with theoretical predictions. |
