A Voltage Vector Superposition Based Control Strategy for High Voltage Capacitor Ageing Test Used Multilevel Cascaded Converter Fed with Single DC Source

In order to design a high voltage capacitor ageing tester, topology of multilevel cascaded H-bridges is used. Considering the economics of the system, the converter contains only one dc source and the rest of H-bridges are fed with capacitors. However, the challenge brought with economy is control of the capacitor voltages. Existing researches mostly based on phase-shifting modulation approach. In this paper, a voltage vector superposition based control strategy and a method to select dc voltages are proposed. This control approach has merits of simple control principle and control parameters are easy to design. In the end of this paper, the simulation results validate this control strategy.