A High-Gain, High-Voltage Pulse Generator Using Sequentially Charged Modular Multilevel Converter Submodules, for Water Disinfection Applications

Modularity, redundancy, and scalability are the key features recently sought in high-voltage (HV) pulse generators (PGs) for electroporation applications. Such features are gained by utilizing modular multilevel converter (MMC) submodules (SMs). In this paper, two arms of MMC half-bridge SMs (HB-SMs) are utilized for generating bipolar/unipolar HV pulses for disinfection process in water treatment applications. The HB-SM capacitors are charged sequentially from a low-voltage dc input source via a resistive-inductive branch and a reverse-blocking switch (which is turned ON/OFF at zero voltage/current conditions). The energy losses of the proposed capacitor charging technique are established mathematically as well as the charging time per SM capacitor. Therefore, the proposed sequential PG (SPG) is able to generate high repetitive pulse rates with high efficiency regardless the HV level of the pulse. Different characterizations of bipolar rectangular pulses can be generated. The proposed topology is assessed by MATLAB/Simulink platform and scaled-down experimentation. The results establish the viability of the SPG topology for the HV pulse generation for water disinfection applications.