Hiren Canacsinh

Generalized solid-state marx modulator topology

A generalized circuit topology for bipolar or unipolar high voltage repetitive pulse power applications is proposed. This circuit merges the negative and positive solid state Marx modulator concepts, which take advantage of the intensive use of semiconductor devices to increase the performance of the original dissipative Marx modulators. The flexibility of the proposed modular circuit enables the operation with negative and/or positive pulses, selectable duty cycles, frequencies and relaxation times between the positive and negative pulse. Additionally, the switching topology enables the discharge of the parasitic capacitances after each pulse, allowing the use of capacitive loads, and the clamping of inductive loads, recovering the reset energy back to the main capacitors. Analysis of efficiency and power loss will be addressed, as well as experimental details for different conditions based on laboratory prototype, with 1200 volt Insulated Gate Bipolar Transistors (IGBT), diodes, and 4.5 muF capacitors.

Marx-Type Solid-State Bipolar Modulator Topologies: Performance Comparison

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.

New solid-state Marx topology for bipolar repetitive high-voltage pulses

A novel bipolar high-voltage modulator topology, based on the Marx generator concept, is proposed for high-voltage repetitive pulsed power applications. The proposed topology is a generalized version of the negative and positive all-solid-state Marx modulator concepts, which takes advantage of the intensive use of power semiconductor switches to increase the performance of the classical circuit, strongly reducing losses and increasing the pulse repetition frequency. Additionally, the proposed topology enables the use of typical half-bridge semiconductor structures while ensuring that the maximum voltage blocked by the semiconductors is the voltage of the capacitor in each stage. Due to semiconductor topology used the output voltage is very flexible. Hence, it is possible to change from negative to positive unipolar to bipolar pulse, with different duty cycles and different switching patterns. Experimental results are presented and discussed. A laboratory prototype with 10 kW peak power, of this bipolar solid-state modulator circuit, was assembled 1200 V IGBTs and diodes, operating with 1000 V d-c input voltage and 10 kHz frequency, giving 2 kV bipolar pulses, 5 A, with 5 mus into a resistive load.

Comparison Between Monopolar and Bipolar Microsecond Range Pulsed Electric Fields in Enhancement of Apple Juice Extraction

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.

Solid state marx modulator with blumlein stack for bipolar pulse generation

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 solidstate 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.

New technique for uniform voltage sharing in series stacked semiconductors

This 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.

New Repetitive Bipolar Solid-State Marx Type Modulator

A broad circuit topology for bipolar or unipolar high-voltage repetitive pulse power applications is proposed. This circuit constitutes a merging version of the negative and positive solid-state Marx modulator concepts, which take advantage of the intensive use of semiconductor devices to increase the performance of the classic circuit. The flexibility of the proposed modular circuit enables the operation with negative and/or positive pulses, with different duty cycles, frequencies and relaxation times between the positive and negative pulse. Additionally, the switching topology enables the discharge of the parasitic capacitances after each pulse, allowing the use of capacitive loads. A 60 kW peak power laboratory prototype was assembled with four stages, using 1200 V IGBTs and diodes, operating with 1000 V dc input voltage and 2 kHz frequency, giving 4 kV / 15 A bipolar pulses, with 5 mus pulse width and 5 mus relaxation time into a resistive load.

Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research

A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.

Solid-State bipolar Marx modulator modeling

A mathematical model that simulates the operation of a solid-state bipolar Marx modulator topology, including the influence of parasitic capacitances is presented and discussed as a tool to analyze the circuit behavior and to assist the design engineer to select the semiconductor components and to enhance the operating performance. Simulations show good agreement with experimental results, considering a four stage circuit assembled with 1200 V isolated gate bipolar transistors and diodes, operating at 1000 V dc input voltage and 1-kHz frequency, giving 4 kV and 10-μs output pulses into several resistive loads. Results show that parasitic capacitances between Marx cells to ground can significantly load the solid-state switches, adding new operating circuit conditions.

Solid-state Marx type modulator for Plasma Based Ion Implantation applications

This paper presents the first results of an innovative solid-state Marx type modulator connected to a Plasma Based Ion Implantation (PBII) system. The PBII system has two main objectives; support surface engineering research and assist the development of new pulsed power modulators for plasma applications. The results of preliminary tests done in nitrogen gas atmosphere, with 1011 cm−3 ion density and 0.1 Pa pressure are discussed. About 25 µs width, 1 kHz negative pulses, of ∼10 kV negative amplitude, were applied to a metallic cylinder (100 mm × 10 mm) vertically placed on it, drawing 6 A peak current. The modulator limits the plasma short-circuit up to 100 A per pulse.