Control of a Modular Multilevel Converter over the entire operating range

  • A Modular Multilevel Converter (MMC) test bench shall be built at the Institute of Electrical Engineering of the Karlsruhe Institute of Technology (KIT). The MMC shall be galvanic isolated from the power grid and behave as a universal three-phase voltage source. The MMC is powered by a 1AC square-wave voltage and therefore an energy control and balancing control for the entire operating range should be implemented in MATLAB/Simulink. Furthermore, the occurring energy pulsation and capacitor ripple current over the entire operating range must be determined.

    As first part of the thesis the student should become familiar with the basic principle of the MMC and current and energy control. This also includes an introduction to MATLAB/Simulink and PLECS.

    After the training period the energy control should be adapted for a square-wave powered 1AC-3AC MMC for the entire operating range. After successful implementation into the existing simulation the energy pulsation and capacitor ripple current is determined. Also different sorting algorithms and modulation techniques should be investigated with respect to the capacitor ripple current using a model with ideal switches.

    The output filter and the according control can be designed if enough time is available. This also includes the limitation of all controllers.