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In this paper, a new structure of Marx generator (MG) based on buck--boost converter is proposed to generate high-voltage pulses. In this structure, a single-phase inverter is employed to supply parallel diode--capacitor units by positive and negative values of the input dc source (±Vin). The main contribution of this paper is proposing a new switching strategy, by which a group of capacitors are charged properly. Finally, the charged capacitors are connected in series such that the output voltage is equal to summation of the capacitors' voltages. Considering specified value of the output voltage, the number of circuit elements in the proposed structure is reduced in comparison with other topologies of unipolar MG. Furthermore, voltage rating of switches and diodes in the proposed topology is lower than that of other unipolar MG structures. Design of the structure ensures that there is no need to connect the switches in series, when the number of stages is increased. To verify the performance of the proposed MG structure, simulation has been carried out in MATLAB/Simulink. Furthermore, a prototype of the proposed structure has been implemented in the lab. The simulation and experimental results confirm the capability of the structure for generating high-voltage pulses. [ABSTRACT FROM AUTHOR]

This paper presents a 100-kV high frequency transformer/rectifier package, which is capable of a dual output polarity operation. An H-Bridge inverter drives the primary of the high voltage (HV) transformer at a frequency of 20 kHz. The inverter is driven by a Microchip dsPIC33F digital signal controller using peak current mode control with adaptive slope compensation. The HV-tank has two HV-coax output cables with a grounded shield on each cable. If the center conductor of the coax cable designated as negative output is grounded, positive voltage is obtained from the coax cable designated as positive output and vice versa. This paper provides design details and experimental results from tests of the entire system. [ABSTRACT FROM PUBLISHER]

Low-temperature plasma ion mobility spectrometry (LTP-IMS) is the method to identify some materials by measuring concentration of gas phase ions. IMS used in a wide range of laboratory-based biomedical research studies. A nanosecond pulse generator is necessary for LTP-IMS apparatus to enable direct analysis of various chemical compounds without having to evaporate the analyte or seek a solvent or any reagent. In this paper, a dual Marx pulsed generator for LTP-IMS Ionization power supply is proposed based on a new combination of some solid-state switches including insulated gate bipolar transistor (IGBT) and avalanche bipolar junction transistors (BJTs). The compact dual Marx generator is composed of a series of avalanche BJTs and an IGBT as the trigger switch, where its rise time is reduced from 100 to 5 ns by using an avalanche BJT in its command circuit. In this way, a controllable high-voltage pulse generator has designed, built, and tested. The proposed circuit can be used to generate the repetitive high-voltage pulses necessary for low temperature ionization in advanced IMS apparatus. The output voltage has an amplitude of up to 6 kV with pulse widths in the range of 40–1000 ns and pulse repetition rates up to 2 kHz, having rise time and fall time less than 10 ns independent of the load specifications. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental results of the 36-kW pulsed-power supply for the xenon flash lamp. The continuous conduction mode series-parallel resonant converter is modified. This means that not only the few hundred kilohertz of high switching frequency is introduced to replace the resonant inductor with the leakage inductor of transformer but also the high output current is accomplished by using three-phase delta-connected transformers. In addition, the snubber capacitor of the inverter switches and the power factor correction module is both omitted in the compact structure. Although these main components have changed, the efficiency and power factor of the rated dummy load reach 96% and 0.96%, respectively. Within 36-kW average power, the proposed pulsed-power supply can generate as versatile combination of output pulse. For example, it can generate 20-ms pulse with 1-Hz repetition rate or generate 1-ms pulse with 20-Hz repetition rate. The used insulated gate bipolar transistor is protected from the turn-OFF peak voltage by the snubber circuit, and the effect of the snubber circuit is shown at the actual load condition. [ABSTRACT FROM PUBLISHER]

In the field of electromagnetic launch or other military research, the requirements for the power density of high-voltage capacitor charging power supply (CCPS) are increasing. The design of the cooling system becomes more difficult, especially in the intermittent operation mode, when the power supply exists transient heating process. As the main heating element of CCPS, the inverter unit is the key factor to influence the power density. In this paper, the main factors that influence the temperature rise of the device are analyzed, including the material and size of the heat sink. The rules between the above factors and the transient temperature rise are analyzed by Matlab simulation software. Then, the architecture model of inverter unit is established through ICEPAK software for simulation, which proves the accuracy of the regular. A basis for designing system level power supplies working in intermittent operating mode is provided through the transient thermal design of inverter unit’D The accuracy of the rule is verified through some load short circuit experiments with a 30-kW/6 kV charging power supply. [ABSTRACT FROM PUBLISHER]

The acceleration grid power supply (AGPS) is an important part of the neutral beam injector (NBI) system. With the increase in NBI power, the requirement for output voltage of the AGPS is becoming higher and higher, even reaching to 1000 kV. As the inverter-type high voltage power supply uses inverters located at the lower voltage side to regulate and cut off the output voltage, it is very suitable for high-voltage applications. The proposed scheme for the AGPS of the International Thermonuclear Experimental Reactor (ITER) NBI system comprises five stages, where each stage has an inverter-type power supply with an output voltage of 200 kV. This paper investigates the inverter-type power supply based on neutral point clamped three-phase three-level (TPTL) inverter and three-phase step-up transformer, which is equivalent to an insulated TPTL dc–dc converter connected with a dual dc link. In order to design a preferable controller for the inverter-type power supply, the topology and principles of the TPTL dc–dc converter with duty cycle modulation have been analyzed. It indicates that only when the converter operates at a large duty cycle, the output voltage ripple can be limited to ±5%. Hence, the small signal model of the converter at a duty cycle larger than 2/3 is established. Following the mathematical model, a single-loop PID controller has been designed and a 400 V/6 A prototype has been built. Simulation and experimental results verify the correctness of the theoretical analysis. The system achieves a lower output voltage ripple and fast dynamic response. [ABSTRACT FROM AUTHOR]

A new method to suppress tearing mode and accelerate magnetic island rotation has been explored. To verify this method on the J-TEXT tokamak, a current-pulse power supply is designed to drive the resonant magnetic perturbation coils with a frequency range from 1 to 5 kHz and amplitude of 3 kA, which can create 0.75 G of magnetic perturbation. The current-pulse power supply topology is modified by H-bridge inverter, which can create a bipolar pulsed current. A set of boost capacitors with an isolation diode is added on dc bus just before the inverter. During the current changing time, the boost capacitors can store the energy of inductive load to steepen the current falling edge and create high voltage to accelerate the current rising speed. This modified topology has a rapid current changing edge and the wide range of operating frequency. A small power prototype is built to verify the topology. [ABSTRACT FROM AUTHOR]

When small currents are interrupted by a vacuum switch, it is well known that the chopping current and the associated overvoltage are observed. Many investigations on the current-chopping phenomena in alternating-current (ac) circuits have been carried out, but there are no data available on inverter circuits in spite of their recent wide application to synchronous motor systems. In this paper, chopping-current levels and the overvoltages in an inverter circuit under a simple three-level pulsewidth-modulated control are investigated. As a result, the mean chopping-current level is three to four times higher than that in an ac circuit. In particular, high chopping currents occur only when the timing of the current interruption by the vacuum switch synchronizes with that of the inverter's switching, which we call “double chopping.” High chopping current due to double chopping might be harmful since the high overvoltage proportional to the chopping-current level could damage the insulation of electric equipment. However, we experimentally confirmed that a typical surge suppressor could reduce overvoltage. [ABSTRACT FROM AUTHOR]

This paper presents a model of the typical dielectric barrier plasma discharge at atmospheric pressure, structured as an equivalent electric circuit whose elements are identified with, and deducted from, the main influential variables of the process, namely, the applied gas, the geometry of the reactor, the breakdown parameters, as well as the power supply associated to the dielectric barrier discharge cell. Considering a parallel-plate reactor and a high-voltage sinusoidal power supply, an electrical comprehensive Simulink/MATLAB model has been developed in order to reveal the interaction between these two elements. The main components of this discharge model are as follows: 1) a double dielectric capacitance; 2) a voltage-controlled current source; and 3) a gas capacitance associated to the ionized gas. A sinusoidal voltage of up to 15 kV peak to peak at frequencies of 12.5 and 47 kHz has been applied to the discharge electrodes. The electrical model is based on the power law proposed by Roth, which defines the V --I behavior during the discharge startup. A series of simulations has been carried out in order to estimate the total current and voltage consumed during each discharge and to identify those parameters which are not measurable during the process. Finally, both the experimental and simulated voltage and current results in helium, argon, and nitrogen, as well as their Q--V graphics, are shown, and a comparison between them is discussed. [ABSTRACT FROM AUTHOR]

This paper presents a multiphase driving system for liquid crystal display (LCD) back-light lamps with current balancing feature. The driving system adopts multiple inverters operated with interleaving fashion to drive cold cathode fluorescent lamps (CCFL), which can reduce input current ripple. Additionally, to prevent current imbalance among lamps, a multiphase transformer is introduced in the proposed system. Compared with the conventional single-phase driving system, the proposed one can have the merit of requiring less number of transformers and lower input current ripple. A three-phase driving system with current balancing transformer has been built, from which experimental results have verified the feasibility of the proposed multiphase driving system. [ABSTRACT FROM PUBLISHER]

To achieve the maximum current rising rate, the second-generation fast control power supply (FCPS) applies voltage control mode while retaining the first-generation current tracking mode. When the power supply outputs high voltage, the accompanied frequent overcurrent protection will return the power to dc side, which leads to overvoltage protection, so the current limiting protection is applied. Experimental results prove that voltage mode can greatly improve the ability to suppress vertical unstable displacement of plasma. [ABSTRACT FROM AUTHOR]

The current–voltage characteristics of atmospheric pressure plasma jets with various working gases (He, Ne, Ar, N2, and air) are investigated. Systems of the plasma jets are composed of a syringe needle inserted into a glass tube and are operated by a sinusoidal high-voltage through a dc–ac inverter generating several tens of kilohertz. The various electrode structures with or without the ground electrode are analyzed by using an equivalent circuit model. For the biomedical applications concerning the discharge stability and the electric safety with a low plasma-current and a low voltage operation, the suitable structures of plasma jets for each gas are suggested. For the plasma jets of inert gases (He, Ne, and Ar), the discharge triggered by an external ground electrode seems to be suitable, because the low current of a plasma plume is adjusted readily with a low voltage of 1–2 kV. For the jets of N2 and air, the nozzle of a metal ground electrode at the end of a glass tube is suggested to reduce the operation voltage below 3 kV and to acquire a low plume-current of a few milliamperes exiting the metal nozzle. [ABSTRACT FROM PUBLISHER]

An integrated full-bridge inverter circuit with fewer components and lower volume is proposed. The conventional light sintering system uses several independent power supplies, each having an input voltage source and inverting component. However, the structure of the proposed circuit comprises only one full-bridge inverter with two separated transformers for applying independent dc trigger and simmer output voltages. The separated transformers are considered to have the same operation switching frequency because of the integrated inverter part. When designing the system, we considered not only matching the switching frequency but also turning-on of the xenon flash lamp. Some of the considerations are as follows: no-load characteristic of the lamp at the initial moment, voltage-boosting effect of the parasitic inductance and capacitance, additional simmer output current path for continuous conduction, and dc trigger turn-off moment when the 15-kV trigger output voltage changes the lamp impedance. Here, the successful results of the aforementioned considerations for applying the light sintering technology are presented. The simulation and no-load experiment waveforms are consistent with the analysis of the effects of the parasitic inductance and capacitance. In addition, the waveforms show 15- and 1.0-kV stable output voltages for the dc trigger and simmer power supplies, respectively. Finally, the xenon flash lamp load is tested, and the integrated system is observed to be functional for single or series-connected lamps. [ABSTRACT FROM AUTHOR]

Integrated circuits are inherently complicated and made more by increasing transistor quantity and density. This trend potentially enhances concomitant effects of high-energy ionizing radiation and local or impressed electromagnetic interference (EMI). The reduced margin for signal error may counter any gain in radiation hardness from smaller device dimensions. Isolated EMI and ionizing radiation studies on circuits have been extensively conducted over the past 30 years. However, little focus has been placed on the combined effects. To investigate the effect of combined EMI and ionizing radiation, two complementary metal–oxide–semiconductor inverter technologies (CD4069 and SN74AUC1G04) were analyzed for their static performance in response to both EMI and gamma radiation up to 132 krd(Si). The combined EMI and gamma radiation environment, compared to the isolated effects of each, produced the most severe degradation in inverter performance for both device technologies. [ABSTRACT FROM PUBLISHER]

A simple and easy-to-use electric-circuit model for fluorescent lamps is deduced from experimental tests. The lamp arc is modeled as a power-dependent resistance. By incorporating the lamp model with electronic ballast, design equations for dimmable electronic ballasts using half-bridge resonant inverter are derived, and then the dimming operation characteristics can be prdicted analytically. Detailed analysis and design of a dimmable electronic-ballast fluorescent-lamp circuit with frequency control are presented. Accordingly, design guidelines for determining circuit parameters are provided. An electronic ballast with half-bridge series-resonant parallel-loaded inverter is used as an example for illustrating the design procedure. A prototype circuit for a T8-36W fluorescent lamp is built and tested to verify the validity of the proposed model. [ABSTRACT FROM AUTHOR]