Solid-state Marx Generator Research Articles

A Solid-State Marx Generator with Prevention of through Current for Rectangular Pulses

In solid-state high-voltage pulse generators, switches may be triggered on by fault due to electromagnetic interference, resulting in high through current and breakdown of switches. To generate rectangular high-voltage pulses, this paper proposes a solid-state Marx generator (SSMG) with fast recovery diodes to prevent through current. Only charging currents with the same direction flow through these fast recovery diodes breaks the short-circuit loops in and between stages. A 52-stage SSMG prototype based on the proposed circuit was developed. PSpice simulations and experiments were performed for comparison. It was found that the through current can rise to 250 A without any protection. With 10-μH protection inductors in each state, the through current amplitude drops to 50 A. Under the same condition, there is no continuous through current with the proposed fast recovery diodes. Furthermore, 22-kV repetitive rectangular pulses were also obtained in experiments. This proved that the proposed Marx generator can prevent the through current in power cells.

Solid-state Marx generator based on saturable pulse transformer and fast recovery diodes

Solid-state compact Marx generator using saturable pulse transformer (SPT) and fast recovery diodes has been proposed. The primary circuit is switched by three MOSFETs connected in parallel. The SPT functions as a step-up transformer to increase the voltage amplitude and as a closing switch for the secondary circuit. Meanwhile, all the SPTs share the same magnetic core to achieve a compact structure and ensure good synchronization. The energy storage capacitors on the secondary sides are charged through the unsaturated SPT. When the SPT saturates, the capacitors firstly transfer a little energy to the saturated inductors through the diodes reversely during their reverse recovery process. Currents rise quickly in these inductors until diodes totally recover to reverse blocking state. Then capacitors discharge in series to the load and high-voltage pulses are generated over the load. With the currents in the saturated inductors, the front edges of pulses are no longer affected by them but are dominated the turn-off speed of the diodes, which makes high-voltage and high-current pulses with short front edges possible. The regular and cheap fast recovery diodes in the generator act as semiconductor opening switch to sharpen the pulse front edges. Experiments were carried out with a 4-stage Marx generator prototype, 10.8-kV high-voltage pulses with a front edge of 11 ns, a pulse width of 190 ns, were obtained over a 100-Ω resistive load. The total energy efficiency is 49.8%. The proposed Marx generator using regular fast recovery diodes is compact, cheap, and efficient to generate high-voltage pulses with short front edges.

Design and Characterization of a Solid-State Marx Generator for Plasma-Activated Water Generation

Design and Characterization of a Solid-State Marx Generator for Plasma-Activated Water Generation

Rogowski and D-Dot Sensors for Nanosecond High-Voltage and High-Current Pulse Measurements in Impedance-Matched Pulse Generators

To measure the output voltage and current in our impedance-matched solid-state Marx generator we developed a voltage and current sensor integrated with the IMG structure. One of the advantages of our IMG structure is the coaxial inner transmission line (TL). The end of this TL is the output connection, which consists of a grounded ring and a smaller high-voltage (HV) inner conductor (coaxial). This structure is ideal for fitting D-dot and Rogowski-coil sensors, as these sensors can benefit from the strictly defined electric and magnetic fields in this waveguide. We developed D-dot and Rogowski-coil sensors on printed circuit boards (PCB) and show their usability in our application for measuring HV pulses. The sensors have a bandwidth of about 200 MHz, measure voltages up to 20 kV, and currents up to hundreds of amperes. Their simple PCB design makes them easily reproducible and cheap compared to commercial sensors. Although designed for our IMG, they can be fit on any coaxial line. Next, we made passive integrators to partly integrate the differentiated sensor signal, which improves the signal quality when measured with an oscilloscope. Finally, after software signal postprocessing, we achieve far better voltage measurements and similar current measurements compared to commercial probes.

Fast and Flexible, Arbitrary Waveform, 20-kV, Solid-State, Impedance-Matched Marx Generator

We developed a new pulsed power supply to study the influence of the high-voltage (HV) pulse shape on the generation of plasma-activated water (PAW). This article shows the design and implementation of the generator and evaluates its performance on resistive loads. The design is an improved version of the solid-state impedance-matched Marx generator (SS-IMG) concept as previously developed at Eindhoven University of Technology. The IMG concept allows for sub-nanosecond rise time pulses, to be able to create a nonthermal plasma very efficiently. A conventional SS-Marx generator (SS-Marx) circuit is taken as the starting point, and a careful implementation is made with most electrical connections analyzed as transmission lines (TLs). All these TLs are impedance-matched to each other and the load. The implemented generator is able to generate 25 ns to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> duration pulses of 20 kV up to 10-kHz repetition rate in a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> load with about 8 ns rise time and arbitrary pulse shape. Future improvements are suggested which will increase the repetition rate and decrease the pulse rise time to the sub-nanosecond regime.

Modelling of a Resonant Charging Circuit for a Solid-State Marx Generator

For the pulsed electric field treatment of plant material on an industrial scale, Marx-type pulse modulators are used as a pulse source. The combination of a conventional Marx generator design equipped with solid-state switches with the concept of resonant charging via current-compensated chokes enables the set-up of a Marx generator having only one active semiconductor switch per stage. Thereby, the pulse shape is defined by the passive components of the RLC-pulse circuit. In the course of the design of such a resonant charging circuit, common-mode current components through the current-compensated chokes need to be considered. Moreover, especially for a generator having its ground connection at its centre, induced voltages versus ground need to be addressed. Therefore, an investigation based on circuit simulations has been made. The simulations showed that the common-mode current components decay to zero just after the resonant charging process and cause a voltage transient at the terminal of the power supply, which needs to be floating versus ground. In order to reduce the amplitude of this transient, the effects of adding a damping resistor have been studied. However, adding this resistor may involve an increase in the common-mode current components. Moreover, the common-mode current components of different chokes are influenced by the on-time of the switches. In the paper, based on the simulation results, different operation modes with and without the damping resistor are discussed. Thereby, the on-time of the switches has been varied. Selected simulation results have been verified by means of measurements.

A high voltage generation using a hybrid Marx generator with Fibonacci operation

A solid-state Marx generator has been used in high-voltage applications. This paper aims to develop a hybrid solid-state Marx generator with a single inductor. The proposed circuit is composed of a Fibonacci module and a boost module. Unlike traditional Marx generators, the proposed circuit is controlled by four-phase pulses to achieve Fibonacci operation. Furthermore, the output of the Fibonacci module is stepped up by the boost module. Therefore, the proposed circuit allows for higher gain than the traditional Marx generator. Regarding the proposed circuit with two-stages, theoretical analysis and experimental investigation are performed to reveal the circuit characteristics. In the case of six times voltage gain, the component count of the proposed circuit is half that of the traditional Marx generator. Furthermore, in the experimental demonstration, the prototype of the proposed circuit achieves 81 % power efficiency with six times gain.

Multi-stage voltage droop compensation based on resonant circuit for unipolar solid-state Marx Generators.

The low-voltage droop of high-voltage pulses is required to provide stable pulsed electric fields in many applications. Increasing the capacitance of energy storage capacitors increases both the size and the cost of the system. In this paper, four compensation stages based on the resonant circuit have been inserted into a 16-stage solid-state Marx generator to compensate for the voltage droop in different conditions. The nearly linear part of the sinusoidal voltage is precisely added to the load during discharging as compensation, and the rectangular pulsed voltage with little droop can be realized. Different numbers of compensation stages and different resonant inductances can compensate the droop to different levels, which means the compensation effect is also adjustable. Moreover, these compensation stages can operate as common stages in Marx generators as long as we open-circuit the resonant circuits. Since the capacitors in resonant compensation stages are also charged in parallel with capacitors in common stages, no auxiliary power supply is required. Simulating and experimental results show that the droop of a 9kV pulse can be ideally compensated over a 500Ω resistive load at various pulse widths. The pulse width should be shorter than the length of the nearly linear part of the sinusoidal voltage.

A Drive Circuit With Overcurrent Protection for Solid-State Marx Generators

In recent years, all-solid-state high-voltage pulse generators have been widely used in irreversible electroporation for tumor ablation technology. However, high voltage may cause the breakdown of loads that leads to short circuits. The short circuit of loads will generate high short-circuit currents that will affect the performance of semiconductor switches. To improve the reliability and lifetime of solid-state pulse generators, a passive synchronous isolated gate drive circuit with short-circuit protection based on decreasing the gate–source voltage is proposed in this article. To verify the overcurrent protection during the breakdown of loads, a solid-state Marx generator prototype using the drive circuit was built and tests were carried out. The experimental results show that the 205-A short-circuit current was clamped with 90 A in less than 500 ns, while the transient voltage can be neglected. Besides, the response time, the maximum transient voltage, and the maximum current amplitude can all be adjusted.

High Voltage Pulse Generator Based on a Novel Magnetic Isolated Drive Circuit

In order to meet the requirements of high voltage, high power, and compactness for pulse generators used in the field of liquid food sterilization, an all-solid-state Marx generator based on a novel magnetic isolated drive is proposed. The drive circuit uses the magnetic core to transfer the control signal, which adopts core stacking and inverse paralleled secondary side winding. It only needs one drive signal to realize synchronous conduction of the main switch or bypass switch and the complementary conduction of both. The maximum pulse width of drive signal is not limited by the magnetic core saturation. The topology is simple, and the problem of high voltage isolated drive of Marx generator is solved. Based on the novel magnetic drive, a 31-module solid-state Marx generator is built and a prototype test is carried out. The test results show that the maximum instantaneous power of this generator is 1.3 MW (30 kV, 43 A) with a pulse width of 3–10 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s and an adjustable repetition frequency of 0–1 kHz.

Research on the Bipolar Microsecond Pulse Generator Using the Multistage Resonant Charging

In this article, a bipolar pulse generator based on multistage resonant charging has been proposed, which can deliver microsecond-range pulses for medical and industrial applications. The main circuit consists of two sets of identical Marx generators connected back to back with the load between them. It can flexibly output bipolar pulses with adjustable amplitude, pulse width, and frequency. In this research, six eight-stage Marx generators have been employed to verify the performance of the proposed bipolar pulse generator. From the experimental results, the proposed generator can deliver pulses with the amplitude of ±10 kV to no-load and a resistive load of 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> . The repetitive frequency can be adjusted from 1 Hz to 1 kHz, and pulse width can be adjusted from 0.2 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$400~\mu \text{s}$ </tex-math></inline-formula> with 50 ns rising and falling time. The relaxation time between the positive and negative pulses can be determined from 0.2 to 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> . In the high-voltage field, the proposed Marx generator can deliver higher output voltage pulses and has smaller voltage differences between stages than the traditional solid-state Marx generator.

Review on Solid-State-Based Marx Generators

Marx generators are widely used to produce transient high-voltage pulses. The evolution of semiconductor devices and power electronics concepts promotes the development of solid-state Marx generators (SSMGs) and enables them with flexible pulse modulation ability. First, this article sorts out the evolution of SSMGs topologies chronologically. We can see that how the energy efficiency of SSMGs is considerably improved by replacing resistors with diodes and switches and how square-wave pulses are generated by SSMGs based on half-bridge structures. Unipolar and bipolar pulses can be easily produced with different SSMGs. Second, we discuss the influence of rated voltage and rated power of present semiconductor switches on the performances of SSMGs since switches are the key components in pulse generators. To reduce the size and weight of SSMGs, metal–oxide–semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs) with small packages are preferable. Third, synchronous isolated driving of switches as the crucial technique in SSMGs is introduced. Different methods of providing synchronous signals and isolated power to various stages in SSMGs are illustrated. Fourth, the performance including load capacity, droop compensation, waveform modulation, and self-triggering of SSMGs is discussed. In the end, the developing trend of SSMGs is given.

Effective streamer discharge control by tailored nanosecond-pulsed high-voltage waveforms

In this paper we present our solid-state nanosecond pulse source (the solid-state impedance-matched Marx generator) which can generate arbitrary waveforms and which can be used for pulsed discharge generation. The purpose of the development of such a generator is twofold: by being able to change the waveform at will, we aim to control the discharge generated by such pulses very precisely which can be very useful for plasma applications, but also for more fundamental studies. In the presented study, we applied the arbitrary-waveform pulse source for streamer discharge generation in a cylinder-wire-like arrangement and used the arbitrary-waveform capability to change the rise time (in our experiments we used 6.8–26.2 ns) of unipolar positive pulses with 6-10 kV amplitude and 80 ns duration. Additionally, we introduced variations of a step in the rising edge of the waveform. We performed measurements both in air and nitrogen to electrically characterize the discharge while analyzing the streamer propagation in the plasma reactor with intensified charge-coupled device imaging and measured ozone generation (in air). The results show that we can indeed control the propagation of the streamer discharge with the stepped waveform, but that the rise-time variation has little effect on the streamer propagation in our system. However, the streamer velocity and structure differs significantly comparing discharges in nitrogen and air for the same applied voltage waveform. Additionally, for some of the stepped waveforms we found a slight increase of the ozone yield for air at low overall energy densities.

Step-Down DC-DC Converter for Solid-State Marx Generator

A compact step-down dc-dc converter has been developed for applications to solid-state Marx generator. The purpose is to allow Marx switches to be able to operate without direct power supply from the ground level circuits. The main voltage across the switch is used as the power source which is converted to a dc voltage that can be used to power the drivers of the solid-state switches. Experiments have been carried out to demonstrate the ability and the performance of the dc-dc converter, as well as its effectiveness in a four-stage Marx generator.

Solid-State Marx Generator Circuit Based on Inductive Energy Storage

Solid-state Marx generator circuits have been widely studied in recent years. Most of them are based on capacitive energy storage (CES), with the basic principle of charging in parallel and discharging in series. In this article, we propose a solid-state Marx circuit using inductive energy storage, where inductors play the role of principal energy storage element. When combined with an opening switch, the inductor can generate an output voltage of $L$ dI / dt, where $I$ is the inductor current. Multiple circuits can be stacked to obtain output voltage adding, as in Marx circuit using CES. In the demonstration experiments, the test on a four-stage inductive Marx circuit has been carried out. With the charging voltage of −200 V, the output peak voltage of ~9.2 kV was generated on an 800- $\Omega $ load with a rise time of ~46 ns.

Testing of a Bipolar Solid-State Marx Generator for Berlin BESSY II Injection Kicker System

This article describes the preliminary results from the new bipolar solid-state Marx generator proposed for Berlin BESSY II injection system, which includes the following pulse specifications: (1) peak voltage of ±8 kV, (2) peak current of 160 A, (3) impedance of 50 Ω, (4) frequency ≤10 Hz, (5) width of 350 ns, (6) risetime ≤80 ns, and (7) deviation from “Flat top” ≤ ± 1%. The generator is based on SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) in order to allow fast risetime/falltime, where the charging of the main capacitors is from resistive paths. A generator with ten stages, using a dummy load that simulates a kicker magnet, is experimentally tested in order to study the overall performance, and results are presented and discussed.

Investigation and Evaluation of Solid-State Marx Pulse Generator Based on 3-D Busbar

SiC-MOSFET has been widely used in nanosecond pulse power generators due to its excellent switching characteristics. The solid-state Marx generator using SiC-MOSFET has the advantages of modularity, flexible adjustment, and economic reliability. However, due to the limitation of the busbar loop's parasitic inductance, the excellent switching characteristics of SiC-MOSFETs have not yet been fully utilized in solid-state Marx. This article discusses the PCB wiring structure of the single-module of solid-state Marx and the influence of its superimposed spatial distribution parameters on the output pulse waveform. The principle of 3-D busbar structure and mutual inductance cancellation method to reduce the parasitic inductance of pulse busbar loop is proposed. And verify the above principle through electromagnetic simulation and four-stage superposition experiment. The parasitic inductance of the busbar loop is less than 4 nH. The voltage edge of the output pulse is further reduced, the current rise/fall speed is increased by about 2.3 times, and the switching voltage overshoot is reduced by 80%. And the proposed structure effectively suppresses the gate bounce and improves the solid-state Marx pulse characteristics. Finally, the stability and reliability of the system are improved too.

Solid-State Marx Generator Circuit With Inductive Booster

We have modified a solid-state Marx generator by inserting inductors into the circuit so that the inductive energy can boost the output voltage to a level several times as high as $n \times V_{0}$ , where $n$ is the number of Marx stages and $V_{0}$ is the charging voltage of each stage. Switches in the Marx generator are properly controlled allowing certain energy transfer from the capacitors to the inductors before the output begins. As a result, when all capacitors and inductors are connected in series, the voltage generated on the load is from both capacitive energy storage and inductive energy storage. In the demonstration experiment, we have used a 4-stage Marx circuit to generate an output voltage with a peak value of ~ 9 kV on a 400- $\Omega $ load, with a charging voltage of 800 V.

Ultrafast Switching of SiC MOSFETs for High-Voltage Pulsed-Power Circuits

Due to their fast switching capabilities, silicon carbide (SiC) MOSFETs are increasingly used in high-voltage pulsed-power circuits where fast and flexible high-voltage pulses are required (e.g. for plasma-processing applications), such as in our solid-state Impedance-matched Marx generator. The turn-on time of SiC MOSFETs mainly depends on the gate-driving technique and its implementation. Therefore, many studies focus on SiC MOSFET gate-driving methods. In this article, a gate-boosting driving method that was previously proposed for IGBTs is optimized for SiC MOSFETs and applied to a very fast MOSFET to reduce turn-on time as much as possible. A prototype of the optimized gate-boosting driver was built and tested to assess its performance. The test results validate the effectiveness of the optimized gate-driving method and showed that a MOSFET turn-on time of below 2 ns is achievable at a high operating voltage and moderate current and below 3 ns for a wider range of load-current and operating-voltage conditions. Furthermore, current rise rates of 38.7 kA/μs at 356-A load current are possible. All these results are considerably faster than ever demonstrated before.

Compact Solid-State Marx Generator for Repetitive Applications

The Marx generator plays a vital role in a pulsed power system. In this paper, a modified compact bipolar output pulse solid-state Marx generator topology is developed. A three-stage prototype is designed and tested, in which pulse width, polarity, and peak voltage of the output pulse are made variable. It is possible to generate either positive or negative pulses with less rise time. Various components which affect the repetitive frequency of the developed Marx generator are evaluated. Analysis reveals that the total time period TO is a function of capacitor charging time. This is been validated experimentally by operating the Marx generator for different pulse repetition frequencies. The type of charging method solely controls the charging time of the capacitor and hence the repetition frequency.