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This paper proposes a novel open-winding brushless doubly-fed reluctance generator (OW-BDFRG) with dual two-level converters in order to reduce the converter rating and switching frequency for large-scale wind turbine applications. The new converter topology is equivalent to a three-level converter directly connected to the control winding of typical BDFRG. The OW-BDFRG system with this topology structure requires lower converter rating and switching frequency, and has a more flexible control mode, better operation performance, and fault redundancy capability. For the OW-BDFRG, this paper also proposes a new control scheme combining direct power control (DPC) with sliding mode variable structure (SMVS) control to implement the power tracking. The voltage-vector switching table of DPC is redesigned according to the error signals of active and reactive powers of the power winding, as well as the sector location of control winding flux. The active and reactive powers of the OW-BDFRG can be directly decoupled and independently controlled by properly selecting the switching voltage vectors. The novelty of this paper lies in an OW-BDFRG topology driven by dual two-level converters to improve the system characteristics, and the use of SMVS control to improve the DPC accuracy and robustness to parameter variations. Finally, the effectiveness of the proposed system is verified through simulation and experimental studies. [ABSTRACT FROM AUTHOR]

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 allows reduction of the electromagnetic interference 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 bistate 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 bistate 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 HV dc transmission applications. The viability of the proposed UPG converter is validated by MATLAB/Simulink simulation and scaled-down experimentation. [ABSTRACT FROM PUBLISHER]

High-voltage (HV) pulses are used in pulsed electric field (PEF) applications to provide an effective electroporation process, a process in which harmful microorganisms are disinfected when subjected to a PEF. Depending on the PEF application, different HV pulse specifications are required such as the pulse-waveform shape, the voltage magnitude, the pulse duration, and the pulse repetition rate. In this paper, a generic pulse-waveform generator (GPG) is proposed, and the GPG topology is based on half-bridge modular multilevel converter (HB-MMC) cells. The GPG topology is formed of four identical arms of series-connected HB-MMC cells forming an H-bridge. Unlike the conventional HB-MMC-based converters in HVdc transmission, the GPG load power flow is not continuous which leads to smaller size cell capacitors utilization; hence, smaller footprint of the GPG is achieved. The GPG topology flexibility allows the controller software to generate a basic multilevel waveform which can be manipulated to generate the commonly used PEF pulse waveforms. Therefore, the proposed topology offers modularity, redundancy, and scalability. The viability of the proposed GPG converter is validated by MATLAB/Simulink simulation and experimentation. [ABSTRACT FROM PUBLISHER]