High Voltage DC Power Supply Research Articles

EAST装置ECRH高压直流电源的研究与设计

高压直流电源是ECRH (Electron Cyclotron Resonance Heating)系统最重要的组成部分之一，其工作的稳定性与可靠性直接影响整个系统的运行。本文介绍了一种ECRH高压直流电源的研制方案，用PSM (Pulse Step Modulate)模块电源技术，克服了传统高压电源单机体积大、效率低、网侧低次谐波污染、功率因数低、输出纹波大、动态响应慢等缺点，同时具备1 kHz的调制能力。并通过Simplorer软件仿真和实验，验证了该设计方案的正确性。 High voltage DC power supply is one of the most important parts of ECRH (Electron Cyclotron Resonance Heating) system, and its stability and reliability directly affect the operation of the whole system. The article introduces a design method of ECRH, using PSM (Pulse Step Modulate) module power supply technology, which overcomes the shortcomings of the traditional high voltage power supply, such as large single volume, low efficiency, net side low harmonics pollution, lower power factor, larger output ripple, slower dynamic response and so on. Meanwhile, it has the capacity of 1 KHZ modulation. Furthermore, the simulations of the Simplorer Software and the results of experiment are provided to verify the accuracy of the proposed design method.

Analysis of a Fifth-Order Resonant Converter for High-Voltage DC Power Supplies

Power transformer is one of the most complex parts of power converters. The complicated behavior of the transformer is usually neglected in the power converter analysis and a simple model is mostly used to analyze the converter. This paper presents a precise analysis of a fifth-order resonant converter which has incorporated the resonant circuit into the transformer. The derived model, which is based on the accurate model of the power transformer, can fully predict the behavior of the fifth-order resonant converter. The proposed fifth-order resonant converter is able to effectively reduce the range of phase-shift angle from no load to full load for a fixed-frequency phase-shift control approach. Therefore, the converter is able to operate under zero voltage switching during entire load range with a fixed-frequency control method. Also, the proposed converter offers a high gain which leads to a lower transformer turns ratio. A 10-kVDC, 1.1-kW prototype has been prepared to evaluate the performance of the proposed converter. The experimental results exhibit the excellent accuracy of the proposed model and the superiority of the performance compared to the lower order resonant converters, especially for high-voltage applications.

Effect of Charged Sphere Size on Electrostatic Discharge Generated while Approaching a Stationary Object

SUMMARY This study experimentally clarified that changing the size of a charged object affects the characteristics of the electrostatic discharge (ESD) that occurs when a charged object moves toward a stationary, grounded object. The spark lengths and discharge currents were measured as charged, metallic, spherical electrodes of different diameters approached a stationary grounded object at different speeds. The charge voltages of the dc high-voltage power supply were +4.0 kV and +6.5 kV. According to the results, the average spark length tended to shorten with the speed of the spherical electrodes. The change in the average spark length with the speed of the 5.0-mm-diameter spherical electrode was faster than that for the 15.9-mm-diameter spherical electrode. The average peak value of the first peak of the discharge current for the 5.0-mm-diameter spherical electrode was greater than the average value for the 15.9-mm-diameter spherical electrode when the approach speed was greater than 5 mm/s for both spherical electrodes. The peak value, rise time, and rising speed of the first peak of the discharge current also correlate with the spark length, and the correlation can be explained qualitatively an the empirical equation deduced from the resistance formula proposed by Rompe and Weizel.

Experimental analysis of the evolution of an electrified drop following high voltage switching

We report experimental results on the electrohydrodynamic behavior of drops following high voltage switching. A pendant drop was placed between two parallel electrodes. Then, a DC high voltage power supply was switched on. The voltage difference between the two electrodes reached the prescribed value through an exponential relaxation process with a characteristic time of the order of some tenths of a second. The drop’s free surface deformation was precisely measured as a function of time. The drop’s evolution can be regarded as a quasi-equilibrium process for subcritical voltages. The instantaneous free surface deformation perfectly matched the equilibrium solution for a voltage which increased over time. The rate at which the electric charge migrated to the free surface was measured precisely by fitting the equilibrium solution to the experimental free surface deformation. For supercritical voltages, the drop’s evolution consisted of two stages: a quasi-equilibrium process until the voltage difference reached its critical value, and a dynamical regime driven by the surface tension force and leading to the drop’s breakage.

Experimental Study of a Gas Jet Generated by an Atmospheric Microcavity Discharge

A study of a one-side-opened microcavity discharge in atmospheric-pressure air is reported. This discharge is powered by a DC high voltage power supply. The discharge regime can be self-pulsed or continuous depending on the magnitude of the discharge current. A gas jet, generated by the discharge in the microcavity, can be used to act on an external airflow passing near the orifice of the microcavity in order to control the airflow. Our experiments clearly show that the gas jet significantly disrupts a smoke column passing near the orifice of the microcavity. The smoke column deviation periodically varies when the electrical discharge is in the pulsed regime, whereas in the continuous regime, it becomes constant. Optical emission spectroscopy measurements were performed, and the gas temperature in the cavity as a function of the mean discharge current was estimated.

Review of Recent HV-LED Technology

LEDs for lighting application are becoming widely adopted due to economic, energy and environmental reasons. LEDs are conventionally powerd by low-voltage DC sources. More and more recent research works have been focusing on an integrated LED chip directly driven by high-voltage DC power supply (HV-LED). The chip structure, the key manufacturing processes and its driving technologies are discussed respectively in this paper, which indicates the advantages of HV-LED including higher luminous efficiency, lower cost and enhanced reliability, and base on this, a HV-LED flip chip is proposed.

Experimental Investigation of the Effects of Various Plasma Actuator Configurations on Lift and Drag Coefficients of a Circular Cylinder Including the Effects of Electrodes

In this paper, the effects of the existence of plasma actuator electrodes and also various configurations of the actuator for controlling the flow field around a circular cylinder are experimentally investigated. The cylinder is made of PVC (Polyvinyl Chloride) and considered as a dielectric barrier. Two electrodes are flush-mounted on the surface of the cylinder and are connected to a DC high voltage power supply for generation of electrical discharge. Pressure distribution results show that the existence of the electrodes and also the plasma are able to change the pressure distribution around the cylinder and consequently the lift and drag coefficients. It is found that the effect of the existence of the electrodes is comparable with the effect of plasma actuator in controlling the flow field around the cylinder and this effect is not reported by other researchers. Eventually it is concluded that the existence of the electrodes or any extra objects on the cylinder and also the existence of the plasma are capable of changing the flow field structure around the cylinder so that the behavior of the lift and drag coefficients of the cylinder will be changed significantly.

Control of ZCS-SR Inverter-Fed Voltage Multiplier-Based High-Voltage DC–DC Converter by Digitally Tuning Tank Capacitance and Slightly Varying Pulse Frequency

Conventional pulse-frequency-modulated (PFM) zero-current switching series resonant (SR) inverter-fed voltage-multiplier-based high-voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light load and large output voltage ripple at low switching frequencies. To address these problems, this letter proposes a new control scheme that is based on digitally tuning tank capacitance and slightly varying pulse frequency of SR inverter. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several tank capacitors that are switched into or out of the tank circuit by electromechanical switches. By digitally modulating the tank capacitance, the output voltage changes in steps. The regulation of output voltage between two adjacent steps is achieved by slightly varying the pulse frequency. The proposed control scheme has several features, namely, a wide range of output voltage controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled-down laboratory prototype are presented to verify the effectiveness of the proposed system.

Sample preparation and direct electrospray ionization on a tip column for rapid mass spectrometry analysis of complex samples

A handheld pipette tip column electrospray ionization source (PTC-ESI source) was developed for rapid mass spectrometry analysis at ambient pressure. The PTC-ESI source was made up of three main component parts including a micro DC high voltage (HV) power supply, a micropipette and a disposable micropipette tip filled with a plug of adsorbent. A DC high voltage was applied to the sharp point of the micropipette tip column to induce electrospray ionization. The PTC-ESI source was successfully used for direct analysis of basic organic compounds, organic acids and peptides in a simple matrix. In the case of complex samples, micro-extraction based on the adsorbent phase filled in the pipette tip was used to remove impurities and concentrate target analytes prior to ionization. The eluting solution was not pipetted out, but directly dispersed in the form of electrospray from the pipette tip for ionization. The effectiveness of the PTC-ESI source has been further demonstrated by fast analysis of therapeutic compounds and endogenous bioactive chemicals in complex biological samples.

The Design of High Voltage DC Power Supply of 4.6GHZ/500MW LHCD

The steady-state and transient performances of the power supply system of LHCD (Lower Hybrid Current Drive) heating system are highly demanded which makes it difficult to design the power source. In this thesis, the method of designing the 4.6GHZ/6MW power source of LHCD of EAST is discussed. And the results of the experiment are provided and some special characteristics are analysed to prove the accuracy of the method.

Polarity Inversion DC-DC Power Conversion Circuit with High Voltage Step-up Ratio

A novel polarity inversion dc-dc power conversion circuit that features the high input to output step-up voltage conversion ratio characteristics is presented for high voltage DC power supply applications. The proposed circuit features the reduced voltage stresses of the components compared to those of the conventional ones. The operational principles of the proposed circuit are analyzed and comparative features are presented. The simulation results and experimental results are presented to verify the validity of the proposed circuit.

Combined resonant tank capacitance and pulse frequency modulation control for ZCS-SR inverter-fed high voltage DC power supply

Conventional pulse frequency modulated (PFM) zero current switching (ZCS) series resonant (SR) inverter fed high voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light loads and large output voltage ripple at low switching frequencies. To address these problems, this paper proposes a combined resonant tank capacitance and pulse frequency modulation based control approach. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several resonant capacitors that are switched into or out of the tank circuit by electromechanical switches. The output voltage of the converter is regulated by digitally modulating the resonant tank capacitance and narrowly varying the switching frequency. The proposed control scheme has several features, namely a wide range of controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled down laboratory prototype are presented to verify the effectiveness of the proposed system.

A ns-μs duration, millitesla, exponential decay pulsed magnetic fields generator for tumor treatment

In order to research a new tumor treatment method using exponential decay pulsed magnetic fields (EDPMF), we developed a EDPMF generator by means of the integration of pulsed power technology and modern power electronics technology. After charging a capacitor with a high voltage dc power supply, EDPMF was generated inside the Helmholtz coils by means of discharging the capacitor through a switch to the discharge resistor. After a brief introduction of basic principle of EDPMF generator, steep pulse formation circuit and Helmholtz coils, two main parts of EDPMF generator, were discussed in detail, especially on design techniques. A height-adjustable platform was designed inside the Helmholtz coils. Cell solution and little animals could be treated on this platform. The peak value, width and repeat rate of the output EDPMF waveform could be adjusted independently in the range of 0 - 1 mT, 160 ns-55 μs and 1 Hz-1 kHz, respectively. The rise time of the output EDPMF waveform was shortened to 70-220 ns by means of choosing quickly operating switch and reducing circuit stray inductance. Magnetic field distribution uniformity was improved via designing better geometrical structure of Helmholtz coils. This was proved by finite element simulation and measurement. Cell experiment in vitro was performed by exposing human liver cancer cells (Hep-G2) to pulsed magnetic field (0.8 mT, 55 μs, 15 Hz) using this generator and the result showed that proliferation of cancer cells in treated group was significantly (P<;0.01) inhibited. This suggests possible clinical application using this kind of EDPMF for local tumor treatment.

Development of a Small Size Spark Chamber by use of Automobile Spark Plug for the Purpose of Educational Demonstration

We constructed a small size spark chamber for use in educational demonstration at Korean high school. For produce required high voltage electrical pulses in the spark chamber, we used an commercial automobile spark plug. A 10 kV DC high voltage power supply which was needed also to operate spark chamber was made by use of Cockroft-Walton circuit. As a spark chamber inner gas, we used low cost argon gas. Finally, we observed electrical sparks which were happened by the incident cosmic muon particles in the spark chamber.

Electron cyclotron heating power supplies on DIII-D

The electron cyclotron heating system on DIII-D has been supporting experiments with six gyrotrons. The gyrotrons are connected to three power supplies: two have single modulators, each energizing two gyrotrons, while the third has three modulators that can energize three gyrotrons asynchronously. However, only two gyrotrons can be run synchronously due to the limitation of the high voltage dc power supply providing the input voltage to the modulators. These two configurations mimic proposed architectures of power systems for multiple gyrotron systems and demonstrate their advantages or disadvantages, which will be discussed in more detail. A fourth power system is being built as part of an upgrade to eight gyrotrons. The two future gyrotrons will have depressed collectors. A 1.2 MW gyrotron will be delivered in mid-2011 and the design of a 1.5 MW gyrotron has been initiated. This fourth power supply will have two modulators to independently energize the cathode of each gyrotron. Commercially available high voltage amplifiers will provide the body voltage. It will also have a solid-state crowbar instead of an ignitron crowbar. This power supply is described in more detail, as well as the testing performed on the solid-state crowbar to prove its performance.

High Voltage DC Power Supply Used in Electrospinning

Power is the direct force in the process of electrospinning, as voltage takes one of the great main roles effecting the quantity of the fiber, making a model of the generater would be in sense to control the morphology.On analysising the working principle,this paper first design a suitable high voltage dc power,and then take an exam in the Simulink environment of Matlab 2009,finally it was certified to be right comparing to the standard situation.

Submicrosecond Pulsed Power Capacitors Based on Novel Ceramic Technologies

Capacitor energy density for submicrosecond discharge applications was investigated for capacitors based on the following: 1) polymer–ceramic nanocomposite (PCNC); 2) antiferroelectric (AFE); and 3) paraelectric (PE) ceramic dielectrics. The developmental PCNC dielectric enabled design, fabrication, and testing iterations to be completed relatively rapidly. The PCNC capacitors were nominally 4 nF and were tested to dc potentials of at least 75 kV. The capacitors were then charged from 20 to 48 kV with a dc high-voltage power supply and discharged into a nearly critically damped test circuit of up to 5 pulses/s (pps) repetition rate for lifetime testing. The discharge time was 65 ns. Shot life as a function of the charge voltage was compared for three design iterations. Changes in the manufacturing of the PCNC capacitors have yielded up to 100x improvements in pulse discharge life. The 1–2-kV prototype, nonlinear (antiferroelectric and paraelectric) multilayer ceramic capacitors had zero-voltage capacitance ratings of between 60 and 300 nF. They were charged to their operating voltage and discharged into a nearly critically damped load in 2–6 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{s}$</tex> </formula> , depending on their capacitance, at repetition rates of up to 75 pps. Their operating voltage for fast, repetitive discharge was determined for lifetimes consistently over <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{5}$</tex> </formula> shots. Discharge energy densities of 0.27–1.80 J/cc and energy losses of 7.9–36.8% were obtained for the packaged multilayer capacitors with different formulations of nonlinear dielectrics. Increased field-induced strain was correlated with increased permittivity and contributed to the limitations on the operating voltage. Multilayer ceramic capacitors fabricated from AFE and PE ceramic dielectrics have the potential to achieve high energy density owing to their high relative permittivities that vary with applied electric field, assuming they can be scaled up to sufficiently high voltages.

Development of 70kV, 22A DC power supply for High Power RF and microwave tubes

Our institute (IPR) is involved in the development of High Power RF and Microwave sources for various fusion related heating and current drive applications. All the high power RF and microwave tubes e.g. Klystron, Gyrotron tetrode etc need a high voltage DC power supply to deliver the required high power with necessary protections. To cater to the initial testing and commissioning requirements, the development of 70kV, 22A power supply is initiated. The supply ratings are chosen to meet general tube requirements i.e. Klystron, Gyrotron and Tetrode used in RF group. The supply would be a part of test facility, rather than a regular supply for use in an experiment. Hence some ripple and regulation requirements are relaxed to optimize the cost. However all protections including crowbar protection are accommodated. This supply when ready enables continuous full power testing of TH 2103D Klystrons, GLGD-82.6/0.2 Gyrotron and short time (3Sec-"ON", 120Sec-"OFF") full power testing of 1.5MW Tetrode. This paper presents analysis of requirements of various tubes, power supply rating optimization, topology selection, protection requirements and other facilities required. Remote monitoring through DAC and remote control requirement from various locations, are highlighted. Present status of development is mentioned.

The Effect of the Electrohydrodynamic on the Two-Phase Flow Pressure Drop of R-134a during Evaporation inside Horizontal Smooth and Micro-Fin Tubes

This article concerns the pressure drop caused by using the electrohydrodynamic (EHD) technique during evaporation of pure R-134a inside smooth and micro-fin tubes. The test section is a counter-flow concentric tube-in-tube heat exchanger where R-134a flows inside the inner tube and hot water flows in the annulus. A smooth tube and micro-fin tube having an inner diameter of 8.12 mm and 8.92 mm, respectively, are used as an inner tube. The length of the inner tube is 2.50 m. The outer tube is a smooth copper tube having an inner diameter of 21.2 mm. The electrode, which is a cylindrical stainless steel wire having diameter of 1.47 mm, is placed in the center of the inner tube. The electrical field is established by connecting a DC high voltage power supply of 2.5 kV to the electrode while the inner tube is grounded. Experiments are conducted at saturation temperatures of 10–20°C, mass fluxes of 200–600 kg/m2s, and heat fluxes of 10–20 kW/m2. The experimental results indicate that the application of EHD introduces a small pressure drop penalty. New correlations for the pressure drop are proposed for practical applications.

Embedded design based virtual instrument program for positron beam automation

Automation of positron beam experiment with a single chip embedded design using a programmable system on chip (PSoC) which provides easy interfacing of the high-voltage DC power supply is reported. Virtual Instrument (VI) control program written in Visual Basic 6.0 ensures the following functions (i) adjusting of sample high voltage by interacting with the programmed PSoC hardware, (ii) control of personal computer (PC) based multi channel analyzer (MCA) card for energy spectroscopy, (iii) analysis of the obtained spectrum to extract the relevant line shape parameters, (iv) plotting of relevant parameters and (v) saving the file in the appropriate format. The present study highlights the hardware features of the PSoC hardware module as well as the control of MCA and other units through programming in Visual Basic.