Browsing by Author "Canacsinh, Hiren"
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- Comparison between monopolar and bipolar microsecond range pulsed electric fields in enhancement of apple juice extractionPublication . Brito, Paula S.; Canacsinh, Hiren; Mendes, João Paulo; Luis Redondo; Pereira, Marco TeotónioThe 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 mu s, 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.
- Dual resonant voltage droop compensation for bipolar solid-state Marx generator topologiesPublication . Canacsinh, Hiren; Silva, J. Fernando A.; Redondo, Luís Manuel dos SantosThis paper discusses a novel methodology to increase the voltage droop compensation range in generalized solid-state bipolar high-voltage Marx modulators with one resonant stage. To maintain the modularity characteristic of bipolar Marx modulators, the imbedding of additional resonant stages is not straightforward. Nevertheless, this paper proposes to add a second resonant stage to the already existing resonant-type voltage droop compensation stage. This second stage increases the voltage droop compensation percentage of a generalized solid-state bipolar Marx generator. The compensation of the bipolar pulse voltage droop is now achieved by adding two auxiliary synchronous compensation resonant voltages, to the output capacitive decaying voltage. Simulation and experimental results are presented for six Marx plus two resonant stages, 16% voltage droop, with 3-kV pulse amplitude, 100-μs pulsewidth, 40-ms relaxation time, and 10-Hz pulse repetition rate.
- Fault tolerance capability and semiconductor's hold-off voltage of solid-state bipolar Marx modulatorsPublication . Canacsinh, Hiren; Silva, Fernando; Luis RedondoTwo solid-state bipolar Marx modulators are analyzed and compared regarding hold-off semiconductor voltages and open-fault tolerance capability. Normal and abnormal operating conditions are considered, such as switch synchronization mismatches, failures, and open faults. Ten-stage laboratory prototypes of two bipolar Marx modulators have been assembled using 1200-V insulated gate bipolar transistors and matching diodes, to operate at 500-V dc input voltage. Outputs are 4-kV bipolar pulses, 1% duty ratio, into resistive loads, and 1-kHz frequency. Lack of synchronization and open-fault tests confirm that only topologies with redundant switches can operate without semiconductors being subjected to double hold-off voltages while presenting current paths to clear faults.
- Hybrid Sepic-Ćuk DC-DC Converter Associated to a SRM Drive for a Solar PV Powered Water Pumping SystemPublication . Cordeiro, Armando; Chaves, Miguel; Canacsinh, Hiren; Luís, Ricardo; Fernao Pires, Vitor; Foito, Daniel; Pires, A. J.; Martins, JoaoThe 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.
- Increasing the voltage droop compensation range in generalized bipolar solid-state Marx moduladorPublication . Canacsinh, Hiren; Redondo, Luis; Silva, J. Fernando; Botelho, PedroThis paper proposes solutions to increase the range of the voltage droop compensation needed to generate long pulses in the generalized solid-state Marx modulator. A novel design method based on the use of resonant circuits in generalized bipolar solid-state Marx modulator is described and evaluated. The increase of the compensation range is obtained by adding an extra auxiliary resonant stage to the existing Marx stages without changing the modularity of the circuit. The compensation is obtained by synchronously adding the voltages of the auxiliary compensation stages to the output voltage. Simulation results are presented for eight stages Marx circuit, ~17% voltage droop, using 6kV bipolar pulses, 100ps pulse duration and 50Hz repetition frequency.
- Marx-Type solid-state bipolar modulator topologies: Performance comparisonPublication . Canacsinh, Hiren; Luis Redondo; Silva, José FernandoThe 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 mu s pulse width and 5 mu s relaxation time into resistive, capacitive, and inductive loads.
- Modeling MARX Generators for maximum pulse repetition rate estimationPublication . Rocha, Luis Lamy; Canacsinh, Hiren; Silva, J. Fernando; Redondo, Luis; Luciano, T.This paper presents a generalized n stage dynamic model for unipolar semiconductor based Marx generators. The model is tailored for the capacitors charging mode to enable the estimation of the maximum pulse repetition rate of the n stage generator. T The maximum pulse repetition rate for the n stage Marx generator can be calculated as a function of the number n of stages, and of the voltage decay allowed in each capacitor (usually less than 10%). Furthermore, given a needed pulse repetition rate the model can estimate the optimum number of stages (n) so that the working voltage of each stage can be selected. Simulation results for a ten-stage (n=10) positive output Marx generators are presented and discussed.
- Modeling of a solid-state bipolar blumlein generator for N stagesPublication . Mendes, João Paulo M.; Luis Redondo; Canacsinh, Hiren; Rossi, Jose O.This paper models an n-stage stacked Blumlein generator for bipolar pulses for various load conditions. Calculation of the voltage amplitudes in time domain at the load and between stages is described for an n-stage generator. For this, the reflection and transmission coefficients are mathematically modeled where impedance discontinuity occurs (i.e., at the junctions between two transmission lines). The mathematical model developed is assessed by comparing simulation results to experimental data from a two-stage Blumlein solid-state prototype.
- Modelling of n-stage Blumlein stacked lines for bipolar pulse generationPublication . Mendes, João Paulo; Redondo, Luís Manuel dos Santos; Canacsinh, Hiren; Vieira, Manuela; Rossi, José O.A Blumlein line is a particular Pulse Forming Line, PFL, configuration that allows the generation of high-voltage sub-microsecond square pulses, with the same voltage amplitude as the dc charging voltage, into a matching load. By stacking n Blumlein lines one can multiply in theory by n the input dc voltage charging amplitude. In order to understand the operating behavior of this electromagnetic system and to further optimize its operation it is fundamental to theoretically model it, that is to calculate the voltage amplitudes at each circuit point and the time instant that happens. In order to do this, one needs to define the reflection and transmission coefficients where impedance discontinuity occurs. The experimental results of a fast solid-state switch, which discharges a three stage Blumlein stack, will be compared with theoretical ones.
- New Technique for Uniform Voltage Sharing in Series Stacked SemiconductorsPublication . Luis Redondo; Canacsinh, Hiren; Silva, José FernandoThis paper describes the operation of a solid-state series stacked topology used as a serial and parallel switch in pulsed power applications. The proposed circuit, developed from the Marx generator concept, balances the voltage stress on each series stacked semiconductor, distributing the total voltage evenly. Experimental results from a 10 kV laboratory series stacked switch, using 1200 V semiconductors in a ten stages solid-state series stacked circuit, are reported and discussed, considering resistive, capacitive and inductive type loads for high and low duty factor voltage pulse operation.
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