Cockcroft-Walton Research Articles

Switching Strategy Development, Dynamic Model, and Small Signal Analysis of Current-Fed Cockcroft-Walton Voltage Multiplier

High voltage generation, is one of the main applications of the Cockcroft-Walton voltage multiplier (CWVM), however recently this structure is investigated to be used for high step-up DC-DC applications. This paper discusses dynamic behaviour and small-signal modelling of a CWVM based DC-DC converter and investigates how switching strategy can affect the dynamic performance of the converter. This study firstly presents, a new switching method, the steady-state relations are derived and compared to the conventional switching strategy, which shows that the proposed method equilibrates the voltage and current stress of the switches and decreases the current ripple of the input inductor. Then, the converter is dynamically modelled and analyzed using the pole-zero map. The analysis shows that the proposed switching strategy improves the dynamic behaviour of the converter. The effect of the passive elements on dynamic performance is also discussed. Experimental results are presented for a 160 W prototype to validate the evaluated performance and the dynamic analysis.

Non-Isolated DC–DC Power Converter With High Gain and Inverting Capability

As the voltage gain of converter increases with the same ratio, the current gain also increases, this increase in current gains will affect the size of the input and the output capacitor. To reduce the ripple in the input current with simultaneous decreasing the input current ripple, a novel current fed interleaved high gain converter is proposed by utilizing the interleaved front-end structure and Cockcroft Walton (CW)-Voltage Multiplier (VM). The “current fed” term is used because, in proposed circuitry, all the capacitors of CW-VM are energized by a current path via inductors of the interleaved structure. The proposed converter can be applied as an input boost up the stage for low voltage battery energy storage systems, photovoltaic (PV) and fuel cell (FC) based DC-AC applications. The anticipated topology consists of the two low voltage rating switches. The main benefits of the anticipated converter configuration are the continuous (ripple free) input current, high voltage gain, reduced switch rating, high reliability, easy control structure and a high percentage of efficiency. The proposed converter’s working principle, mathematical based steady-state analysis, and detailed component design are discussed. The parasitic of the components has been considered in the analysis to show the deviation from the ideal cases. A detailed comparison with the other available converters is presented. The experimental results of the 300W prototype are developed to confirm the performance and functionality of the anticipated DC-DC converter.

Sensorless Voltage Observer for a Current-Fed High Step-Up DC-DC Converter Using Extended Kalman Filter

In high voltage applications, sensorless voltage control techniques can reduce the cost and increase the reliability of DC-DC converters. In this paper, a sensorless voltage observer for a current fed Cockcroft-Walton voltage multiplier is designed. The first step is to derive the converter model. Since any inaccuracy in the derived model can result in a discrepancy between the observed voltage and the actual output voltage, an accurate model is derived, which incorporates the influential elements. Then, two voltage observers based on the extended Kalman filter (EKF) are designed and used to estimate the output voltage, transformer magnetizing current and inductor current for two different configurations of the high step-up DC-DC converter. Experimental and simulation results of the system show the efficiency of the observers. The proposed observers represent good precision as the main parasitic parameters are considered in the converter model.

Control of Radiation Defects and Na Clusters in the Process of Radiation Degradation of Natural Stone Salt Single Crystals

Using the methods of positron annihilation and optical spectroscopy, the effect of gamma (Co60) and electron irradiation (Cockcroft–Walton accelerator) on NaCl single crystals, followed by annealing at various temperatures. It was found that electron color centers are effective traps of positrons diffusing in the lattice. At the same time, hole centers do not capture positrons. It was shown that positrons are captured by sodium clusters formed in the bulk of NaCl crystals upon annealing (443 K) of irradiated (2650 Mrad) samples. The annihilation characteristics of captured positrons allow us to estimate size of sodium clusters R = 23.0 nm and their concentration Nx = 5.3 × 1017 cm–3. Taking into account the fact that modern optical and positron spectrometers are quite compact and sensitive instruments, the monitoring of the processes of radiation degradation of the geological rock of rock salt can be carried out directly at the disposal sites of radioactive waste rather quickly and with the necessary degree of sensitivity to the accumulation of radiolytic products.

Correction to: Behavioral switching model for current‑fed Cockcroft–Walton voltage multiplier

Correction to: Behavioral switching model for current‑fed Cockcroft–Walton voltage multiplier

Behavioral switching model for current-fed Cockcroft–Walton voltage multiplier

After about 80 years of introducing the Cockcroft–Walton (CW) circuit, it is still widely used because of its advantages, such as simplicity and high step-up gain. Several studies focused on the performance and design optimization of the circuit, but a dynamic model of the circuit remains to be established. This study analyzed the operation principles of an n-stage current-fed Cockcroft–Walton (CF-CWVM) during transient and steady-state operations. Then, an approach was derived to achieve a mathematical model for CF-CWVM with an arbitrary number of stages. A mathematical model for one- and two-stage CF-CWVM was developed, and its results were compared with simulation results. The theoretical model and simulations were validated by providing a prototype of CF-CWVM and comparing the results with the model outputs.

Drift field generation with Cockcroft-Walton voltage multiplier in xenon gas for AXEL 0vββ search detector

For noble gas Time Projection Chambers (TPCs) in the field of rare event searches, operation of high voltage to generate an electric field is a key point. We designed a new structure of electrodes to shape a strong and uniform drift field without electric discharge, in which electrodes of two different radius are used. We also developed Cockcroft-Walton voltage multiplier as a high voltage generator inside a pressure vessel. We achieved −30.0 kV output and examined such kind of voltage generator is feasible as a high voltage supplier in a TPC.

Multiple output dc-dc converter derived from Cock-Croft Walton voltage multiplier and SIMO converter

Multiple output dc-dc converter derived from Cock-Croft Walton voltage multiplier and SIMO converter

Design of Efficient Power Supply for the Proper Operation of Bio-Mimetic Soft Lens

Soft Robotics is one of the emerging and top-notched researched fields in Robotics which collaborate and Interact with Human Machine Interface (HMI). Several power electronics and electrical devices are used for the proper operation of these robots, among them high voltage power supply plays a vital role. Several approaches are used for the design of the high voltage power supply but still there is a deficiency in the design of the power supply which fulfill our desires level (highly efficient and less complex). This paper presents the efficient power supply for the control of bio-mimetic lens. The proposed power supply is designed by the use of boost converter, single phase inverter and the cock-croft Walton Voltage Multiplier. The work employs the use of power electronics for the achievement of the efficient high voltage power supply and boost the level of voltage up to 5 kV. Numerical simulations are performed for the comprehensive testing of the proposed model. Simulink is used for designing of the high voltage supply for simulation work. More-over the results are verified with the designing of laboratory setup. The experimental results are close to the simulation results with an error less than 3%. This proof the validity of proposed high voltage power supply.

Design and Model of Series-Connected High-Voltage DC Multipliers

The generation of high dc voltages is necessary for feeding many technical applications and testing the insulation material of high-voltage dc transmission lines and ac power cables with long lengths. The article proposes a modular multiplier high-voltage dc generator with integrated Cockcroft-Walton (CW) circuits. In this new topology, CW circuits are connected in series to produce a high dc output voltage with low regulation factor (<; 2%) and a negligible ripple factor without the need for costly filters to produce a nearly constant output voltage. The modules are fed by low input ac voltage sources that have the same magnitude and frequency. Numerical simulations using MATLAB/Simulink confirm the viability of the proposed generator. The generator is finally validated by experimental tests on a kV-size prototype.

A NOVEL 1.6 KV HIGH VOLTAGE LOW CURRENT STEP-UP DC-DC CONVERTER WITH COCKCROFT-WALTON VOLTAGE MULTIPLIER FOR POWER SUPPLY MODULES

A high dc voltage is commonly used in many process industries in testing, research laboratories and others. Currently, a high voltage dc is implemented using transformer. In this paper, a novel high voltage low current transformerless step-up dc-dc converter is presented. The proposed design consists of two step-up dc-dc converters with negative feedback signal and 15 stages of Cockcroft-Walton (C-W) voltage multiplier. The dc input voltage of 5 V triggers the first step-up dc-dc converter circuit to generate 30 V dc voltage and the second step-up dc-dc converter circuit boosts up to 100 V dc voltage. Further, diode-capacitor multiplier circuit is connected at the final stage to achieve 1.6 kV dc output voltages at 200 kHz switching frequency. The simulation results indicate that the proposed dc-dc converter can generate 1.548 kV dc voltage with a load current of 0.16 mA at 10 MΩ load resistor. Meanwhile, the experiment results show that the proposed dc-dc converter can generate 1.475 kV dc voltage with 80 % efficiency. The results validate both the simulation and experimental of the proposed high dc voltage power supply module.

Plasma generator: design of six stage cockcroft-walton voltage multiplier 12 kV for impulse voltage generation

Cockcroft-Walton (CW) voltage multiplier is a voltage booster circuit with an array of series-connected only diodes and capacitors. In this research, voltage multiplier is designed to generate voltage up to 12 kV that the modified 6-stage constructed generator. It is designed as circuit charger of storage capacitor (CS) to generate combination wave impulse application which following standard those set in IEC (International Electrotecnical Commission) 61000-4-5 class 4. CS should be charged up to 4 kV according this standard. High impulse voltage and current works repeatedly in a short time, so the charging system is expected to reach targeted voltage within a maximum time of 10 seconds. Besides charging is also required to design of circuit discharger for discharging electric charge inside the CS. It is expected to reach 0 kV within a maximum time of 15 seconds with overdamped technique. There are three results of the research projects such as output voltage of CW voltage multiplier before connecting CS, charging time of CS, and discharging time of CS. The result showed that CW voltage multiplier can generate up to 12.01 kV on simulation and 11.9 kV on experiment. CS can be charged up to 4 kV in 9.8 seconds on simulation and 7.9 seconds on experiment. CS can be discharged in 14.2 seconds on simulation and 10 seconds on experiment. These results are in accordance with the expectation.

Generating High Voltage DC with Cockcroft-Walton Voltage Multiplier for Testing Locally Assemble Electric Field Sensor

This paper describes the construction of a high voltage DC generator using single-phase transformer and Cockcroft-Walton voltage multiplier. The aim is to simulate high voltage DC for simulating electric field produced before a lightning strike near the ground. Lower AC voltage is step up to high AC voltage using a neon transformer. The AC voltage is then converted into high DC voltage using variable stages of Cockcroft-Walton voltage multiplier. The generator HVDC is connected to the adjustable parallel plate to ground. Variable stages of Cockcroft-Walton voltage multiplier produce high voltage magnitude proportional to each stage of it. The electric field generated from high voltage DC can also be varied depending on the distance between DC output plate and ground. The application of high voltage DC in generating electric field useful in testing locally assembled Electric Field Sensor.

Diode Reverse Recovery Process and Reduction of a Half-Wave Series Cockcroft–Walton Voltage Multiplier for High-Frequency High-Voltage Generator Applications

This paper investigates the diode reverse recovery process and reduction of a half-wave (HW) series Cockcroft–Walton (CW) voltage multiplier based on the steady-state analysis for high-frequency high-voltage (HV) generator applications. The diode reverse recovery process for a multistage voltage multiplier is analyzed after the introduction of steady-state operation. The diode reverse recovery problem is the bottleneck to further increase the circuit operation switching frequency for achieving high power density and short HV pulse rise and decay times. The diode reverse recovery problem is mainly caused by the diodes in the first-stage voltage multiplier. It is suggested that the most effective and economic way to alleviate the diode reverse recovery problem is by employing diodes without reverse recovery such as silicon carbide Schottky diodes in the first stage only. The silicon carbide Schottky diode without reverse recovery needs to be used only in the first stage of the voltage multiplier to effectively mitigate the reverse recovery problems at high frequency. The 300 kHz switching frequency three-stage voltage multiplier circuit hardware prototype experimental results finally validate the analysis. A technology demonstrator of a 300 kHz 8 kW 160 kV HV generator based on the proposed hybrid silicon carbide and silicon diode solution for the HW series CW voltage multiplier is provided finally.

A Family of Scalable Non-Isolated Interleaved DC-DC Boost Converters With Voltage Multiplier Cells

In this paper, a family of non-isolated interleaved high-voltage-gain DC-DC converters is presented. This family can be used in a wide variety of applications, such as in a photovoltaic systems interface to a high voltage DC distribution bus in a microgrid and an X-ray system power supply. The general structure of this family is illustrated and consists of two stages: an interleaved boost stage and a voltage multiplier stage. The interleaved boost stage is a two-phase boost converter, and it converts the input DC voltage to an AC square waveform. Moreover, using the interleaved boost stage increases the frequency of the AC components so that it can be easily filtered with smaller capacitors and, therefore, makes the input current smoother than the one from the conventional boost converter. The voltage multiplier cell (VMC) can be a Dickson cell, Cockcroft-Walton (CW), or a combination of the two. The VMC stage rectifies the square-shaped voltage waveform coming from the interleaved boost stage and converts it to a high DC voltage. Several combinations of VMCs and how they can be extended are illustrated, and the difference between them is summarized so that designers can be able to select the appropriate topology for their applications. An example of this converter family is illustrated with detailed modes of operation, a steady-state analysis, and an efficiency analysis. The example converter was simulated to convert 20 V DC to 400 DC , and a 200 W hardware prototype was implemented to verify the analysis and simulation. The results show that the example has a peak efficiency of 97% of this family of converters and can be very suitable for interfacing renewable energy sources to a 400 V DC DC distribution system.

Development of Compact High-Voltage Power Supply for Stimulation to Promote Fruiting Body Formation in Mushroom Cultivation.

The compact high-voltage power supply is developed for stimulation to promote fruiting body formation in cultivating L. edodes and Lyophyllum deeastes Sing. mushrooms. A Cockcroft-Walton (C-W) circuit is employed to generate DC high-voltage from AC 100 V plug power for the compact, easy handling and high safety use in the hilly and mountainous area. The C-W circuit is connected to high-voltage coaxial cable which works for high-voltage transmission and for charging up as energy storage capacitor. The output voltage is around 50 kV with several microseconds pulse width. The dimension and weight of the developed power supply are 0.4 × 0.47 × 1 m3 and 8.1 kg, respectively. The effect of the high-voltage stimulation on enhancement of fruiting body formation is evaluated in cultivating L. edodes and Lyophyllum deeastes Sing. mushrooms using the developed compact high-voltage power supply. The conventional Marx generator is also used for comparison in effect of high-voltage stimulation for fruiting body formation. L. edodes is cultivated with hosting to natural logs and the pulsed high voltage is applied to the cultivated natural logs. The substrate for Lyophyllum deeastes Sing. cultivation consists of sawdust. The results show that the fruiting body formation of mushrooms of L. edodes for four cultivation seasons and that of Lyophyllum deeastes Sing. for two seasons both increase approximately 1.3 times higher than control group in terms of the total weight. Although the input energy per a pulse is difference with the generators, the improvement of the fruit body yield mainly depends on the total input energy into the log. The effect for promotion on fruiting body formation by the developed compact high-voltage power supply is almost same that by the conventional Marx generator.

High voltage-gain full-bridge cascaded dc-dc converter for photovoltaic application.

Over the past few years, high step-up dc-dc converters have been drawn substantial attention because of their wide-ranging application not only in the renewable energy sector but also in many other applications. To acquire a high voltage gain in photovoltaic (PV) and other renewable energy applications, a high step-up dc-dc converter is proposed in this paper. The proposed converter structure consists of a full-bridge (FB) module along with an input boost inductor and a voltage multiplier based on the Cockcroft-Walton (CW) principle with a parallel inductor. The key features of the proposed converter are: 1) high voltage gain with lower voltage stress on the switches, diodes and other passive elements without affecting the number of cascaded stages, 2) a minimum size of boost inductance and cascaded stage capacitance that ensures its compactness and low cost, and 3) a minimal number of major components. Circuit operation, steady-state analysis and various design parameters of the proposed converter are explained in details. In order to prove the performance of the theoretical analysis, a laboratory prototype is also implemented. The peak voltage gain and the maximum efficiency obtained are 11.9 and 94.6% respectively with very low input current ripple and output voltage ripple generated.

A Dual Inductor High Step-Up DC/DC Converter Based on the Cockcroft–Walton Multiplier

A new nonisolated, high step-up dc–dc converter is proposed based on the current-fed Cockcroft–Walton Voltage Multiplier (CW-VM) that can be used as the boosting power stage of converter for low-voltage low power renewable energy sources such as photovoltaic and fuel cells. The proposed converter employs two low-voltage common-emitter switches. Utilizing the current-fed CW-VM eliminates some problems associated with the conventional voltage-fed type such as voltage ripple and load-dependent voltage droop. Other advantages of the proposed converter are continuous input current, high voltage gain, and high efficiency. Steady state operation principles, specifications, and design considerations of the proposed converter are illustrated. Furthermore, efficiency analysis of the converter is performed and discussed. Experimental tests for a 200 W prototype are carried out which confirm the theoretical analysis.

A pixelated Faraday cup for proton beam diagnostics

Diagnostics tools are largely used to tune and set up beams in a vast range of applications. They include particle and nuclear physics, medical physics up to material science and biology, just to mention a few. The requirements on the detectors used to monitor the beam condition accordingly with the specific case. We present here a pixelated Faraday cup we built and used for beam profile monitoring with the peculiar characteristic of simultaneously measuring the proton beam position, shape and intensity. The detector covers a large range of currents from a hundred μ A down to a few nA perfectly matching the range of the proton beam intensity delivered by a 1 MeV Cockcroft–Walton accelerator. The pixel size allows for a beam position determination better than 1 mm.

Medium and Short Wave RF Energy Harvester for Powering Wireless Sensor Networks.

Internet of Things (IoT) is an emerging platform in which every day physical objects provided with unique identifiers are connected to the Internet without requiring human interaction. The possibilities of such a connected world enables new forms of automation to make our lives easier and safer. Evidently, in order to keep billions of these communicating devices powered long-term, a self-sustainable operation is a key point for realization of such a complex network. In this sense, energy-harvesting technologies combined with low power consumption ICs eliminate the need for batteries, removing an obstacle to the success of the IoT. In this work, a Radio Frequency (RF) energy harvester tuned at AM broadcast has been developed for low consumption power devices. The AM signals from ambient are detected via a high-performance antenna-free LC circuit with an efficiency of 3.2%. To maximize energy scavenging, the RF-DC conversion stage is based on a full-wave Cockcroft–Walton voltage multiplier (CWVM) with efficiency up to 90%. System performance is evaluated by rating the maximum power delivered into the load via its output impedance, which is around 62 μW, although power level seems to be low, it is able to power up low consumption devices such as Leds, portable calculators and weather monitoring stations.