A transition arm modular multilevel universal pulse-waveform generator for electroporation applications

High voltage (HV) pulses are used in electroporation to subject pulsed electric field (PEF) onto a sample under treatment. Pulse-waveform shape, voltage magnitude, pulse duration, and pulse repetition rate are the basic controllable variables required for particular PEF application. In practice, a custom-made pulse generator is dedicated for each PEF application with limited flexibility in changing these variables. In this paper, a universal pulse-waveform generator (UPG) is proposed, where the controller software-algorithm can manipulate a basic generated multilevel pulse-waveform to emulate many different PEF pulse-waveforms. The commonly used PEF HV pulse-waveforms can be generated as bipolar or monopolar with controllable pulse durations, repetition times, and voltage magnitudes. The UPG has the ability to generate multilevel pulses that have controllable dv/dt which allow reduction of the electromagnetic interference (EMI) generated by the converter. The UPG topology is based on half-bridge modular multilevel converter (HB-MMC) cells forming two transition arms in conjunction with two bi-state arms, together creating an H-bridge. The HB-MMC cell-capacitors provide a controllable energy source which charge from the dc input supply and discharge across the load, while the two bi-state arms allow charging the HB-MMC cell-capacitors. Hence, the UPG topology offers modularity, redundancy, and scalability. The HB-MMC individual cell-capacitance is low and the cell-voltages are balanced by employing the sorting and rotating algorithm used in conventional HB-MMC topologies for HVDC transmission applications. The viability of the proposed UPG converter is validated by MATLAB/Simulink simulation and scaled-down experimentation