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The operation of generalized Marx-type solid-state bipolar modulators is discussed and compared with simplified Marx-derived circuits, to evaluate their capability to deal with various load conditions. A comparative analysis on the number of switches per cell, fiber optic trigger count, losses, and switch hold-off voltages has been made. A circuit topology is obtained as a compromise in terms of operating performance, trigger simplicity, and switching losses. A five-stage laboratory prototype of this circuit has been assembled using 1200 V insulated gate bipolar transistors (IGBTs) and diodes, operating with 1000 V dc input voltage and 1 kHz frequency, giving 5 kV bipolar pulses, with 2.5 µs pulse width and 5 µs relaxation time into resistive, capacitive, and inductive loads.

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The effect of monopolar and bipolar shaped pulses in additional yield of apple juice extraction is evaluated. The applied electric field strength, pulsewidth, and number of pulses are assessed for both pulse types, and divergences are analyzed. Variation of electric field strength is ranged from 100 to 1300 V/cm, pulsewidth from 20 to 300 μs, and the number of pulses from 10 to 200, at a frequency of 200 Hz. Two pulse trains separated by 1 s are applied to apple cubes. Results are plotted against reference untreated samples for all assays. Specific energy consumption is calculated for each experiment as well as qualitative indicators for apple juice of total soluble dry matter and absorbance at 390-nm wavelength. Bipolar pulses demonstrated higher efficiency, and specific energetic consumption has a threshold where higher inputs of energy do not result in higher juice extraction when electric field variation is applied. Total soluble dry matter and absorbance results do not illustrate significant differences between application of monopolar and bipolar pulses, but all values are inside the limits proposed for apple juice intended for human consumption.

Sub-nanosecond bipolar high voltage pulses are a very important tool for food processing, medical treatment, waste water and exhaust gas processing. A Hybrid Modulator for sub-microsecond bipolar pulse generation, comprising an unipolar solid-state Marx generator connected to a load through a stack Blumlein system that produces bipolar pulses and further multiplies the pulse voltage amplitude, is presented. Experimental results from an assembled prototype show the generation of 1000 V amplitude bipolar pulses with 100 ns of pulse width and 1 kHz repetition rate.

The present paper describes a solar photovoltaic (SPV) powered water pumping system employing a switched reluctance motor (SRM) and a merged Sepic-Ćuk DC-DC converter. The proposed solution was designed to use efficiently the available solar energy in order to supply water pumping systems. Solutions of this kind assume a special importance in the current scenario of natural and renewable resources optimization. The proposed DC-DC converter operates in continuous conduction mode (CCM), which combined with a maximum power point tracking (MPPT) controller, helps to optimize the power of the solar photovoltaic panel (SPV). The proposed DC-DC topology is characterized by high voltage static gain when compared with the classical boost topology and reduced voltage stress across the power switch and diodes. Several simulation and experimental results are presented in order to confirm the characteristics of the proposed solution for water pumping systems.

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Fig. 1. S 2 BM modulator with n stages for bipolar or unipolar pulse generation.Fig. 2. Tested HV topology of the n stages S 2 BM modulator, with auxiliary resonant based voltage droop compensation stage for bipolar or unipolar pulse generation, particular case of circuit of Fig. 1.Abstract-The purpose of this paper is to present and discuss the voltage droop compensation associated with long pulses generated by solid-state bipolar or unipolar high-voltage Marx modulators. In particular a novel design scheme for voltage droop compensation based on resonant circuit in solid-state bipolar (positive and/or negative pulses) high-voltage Marx generator, using off-the-shelf components, design and control, is described. The compensation consists in adding one auxiliary resonant stage to the existing Marx stages, without changing the modularity and topology of the circuit. The auxiliary compensation voltage is added to the output voltage to compensate the pulse voltage droop. Experimental results are presented for five stages Marx circuit, 10% voltage droop, using 1 kV pulse amplitude, 100 µs pulse width, 9.5 ms relaxation time and with 50 Hz pulse repetition rate.