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This paper presents a dual modular multilevel converter (MMC) topology that utilizes energy exchange between adjacent-arm submodules (SMs), operating with out-of-phase modulation. The proposed configuration is applicable to medium-voltage high-power variable-speed drives incorporating open-end stator winding machines. A novel concept of power decoupling between adjacent-arm SMs in the dual MMC topology is realized through high-frequency transformer-based dc–dc converter modules. This concept offers a significant reduction in the sizing requirement of the SM capacitance and the stored energy in the MMC system, while avoiding the problem of wide voltage fluctuations of SM capacitors, especially at low operating frequencies. The proposed configuration can produce dc voltage; therefore, a machine speed range from zero speed to the rated speed is possible under the rated torque operating condition. The operating principles of the proposed dual MMC configuration are elaborated and necessary mathematical analysis is derived. Simulation and experimental results verify the concept of the proposed drive configuration. [ABSTRACT FROM AUTHOR]

In this paper, a new HVDC shunt tap is proposed. The proposed configuration consists of a unidirectional hybrid modular DC–DC converter followed by a voltage source converter for DC–AC conversion to feed a local AC network connected to the tap output terminals. The proposed DC–DC converter consists of a high-voltage valve, and series-connected unidirectional half-bridge Sub-Modules (SMs). Unlike Marx generator circuit concept, the DC–DC conversion in the proposed configuration is achieved by enabling simultaneous charging of series-connected capacitors (i.e. SMs capacitors), and sequential discharging of capacitors. Compared to Marx-generator based switched capacitor DC–DC converters, the proposed configuration has a lower number of semiconductor devices, which affects positively the system cost, and reduces the control complexity. Detailed illustration, design, and control of the proposed approach are presented. Simulation results are presented to validate the proposed approach. [ABSTRACT FROM AUTHOR]

Bipolar repetitive high-voltage pulse generators are commonly used in modern pulsed power applications. Conventionally, bipolar high-voltage pulses can be generated by adding a high-voltage H-bridge at the output stage of a unipolar high-voltage pulse generator which increases complexity and cost of the bipolar high-voltage pulse generator. In this paper, a boost-inverter-based bipolar high-voltage pulse generator with high-voltage gain is proposed. The proposed generator can provide high-voltage bipolar output pulses with the desired specifications from a low input dc voltage. The proposed generator is based on employing two bidirectional boost dc–dc converters, where the load is connected differentially between the boost converters’ output terminals. In the proposed approach, four controlled switches are required. Only two out of these four switches are rated at the high-voltage output level which affects positively the system cost. A detailed illustration of the proposed approach along with the design of its passive components is presented in this study. Simulation and experimental results are used to validate the proposed approach. [ABSTRACT FROM AUTHOR]

Pulsed electric field (PEF) can be used effectively in water treatment applications by passing infected water through two electrodes excited from a high voltage pulsed power supply which guarantees killing the harmful germs. In this paper, a new high-voltage pulse-generator with closed loop control of its output voltage is presented for treating water via underwater pulsed streamer corona discharge. The proposed generator is fed from a low AC voltage source (utility mains 220 V, 50 Hz) which makes it suitable for domestic applications. The proposed topology provides transformer-less operation which reduces the system size and enhances the overall efficiency. The proposed topology is based on capacitor-diode voltage multiplier (CDVM) circuits in conjunction with DC-DC converters (Boost and Buck-Boost converters). The simulation and experimental results elucidate the proposed configuration. [ABSTRACT FROM AUTHOR]

Renewable energy sources, such as offshore wind farms, require high voltage gains in order to interface with power transmission networks. These conversions are normally made using bulky, complex, and costly transformers and high-voltage ac–dc converters with unnecessary bidirectional power flow capability. Multiple modules of single-switch single-inductor dc–dc converters can reach high gains without transformers in these applications due to low semiconductor conduction loss in high-power devices. This paper describes a new approach for high-gain high-voltage dc–dc converters using multiple modules of single-switch single-inductor transformerless converters. Results for low-voltage experimental prototypes show gains of up to 29 p.u. and demonstrate the potential of the approach as high-gain dc–dc converters for offshore wind farms. This paper then demonstrates the viability of multiple-module converters compared to a conventional high-voltage dc converter and a theoretical full-bridge converter due to fewer devices and valves, comparable isolation levels, and ease of interleaving for increased reliability. [ABSTRACT FROM AUTHOR]