Air-core Pulse Transformer Research Articles

Design and Optimization of Air-Core HTS Pulse Transformer for Series-Type Hybrid Circuit Breaker (S-HCB)

Design and Optimization of Air-Core HTS Pulse Transformer for Series-Type Hybrid Circuit Breaker (S-HCB)

A Repetitive Inductive Pulsed Power Supply Circuit Topology Based on HTSPPT

Inductive energy storage for pulsed power supplies is considered to have great potential because its energy density is 1 order of magnitude higher than that of capacitive one. Associating with the superconducting technology and the STRETCH meat grinder circuit, which proposed by the Institute of Advanced Technology, a superconducting inductive pulsed power supply (SPPS) circuit has been proposed by using an air-core high-temperature superconducting pulsed power transformer (HTSPPT) in our previous study. It can not only recapture the energy in the leakage flux and slow down the current change in inductors by using a capacitor, but also reduce the coil loss and the power requirement of the primary source by using superconducting inductors. However, it can be found that the SPPS may generate a large residual current during the discharging phase, which results in an adverse influence on the working frequency and the energy transfer efficiency of the whole system. This paper proposes a modified circuit based on the bridge current switching circuit and HTSPPT. The main principle of the circuit is that the recaptured energy in the capacitor and the residual energy in the secondary are used to precharge the primary inductor for the next cycle, which shortens the charging time, generates continuous current pulses, and improves the energy transfer efficiency. The procedure of the repetitive SPPS is analyzed in detail, and simulations are carried out to explain how the circuit works clearly.

Joint testing of the 3 Tesla ST40 spherical tokamak toroidal field coil test assembly

Spherical Tokamaks used in magnetic fusion have a small centre-stack by design which causes a higher field on the conductor. ST40 [1] is a 3 Tesla spherical tokamak with a major radius of R=40cm and minor radius of a=26cm being built by Tokamak Energy Ltd. The high toroidal field (TF) requirement requires a wire current of 250kA flowing in each of the 24 limbs totalling 6MA in the centre-stack. Joint testing was used to investigate the interface resistance between the centre-stack and return limbs under a variety of contact pressures, using different shims, different coatings on the conductor and soldering. Initially a DC 400A current source was used and later an air-core pulsed transformer delivering up to 16kA of current was specifically designed and built for these measurements. Results from this paper can be used to predict the behaviour of critical joints in the region at the ends of the centre-stack where current is passed to the TF return limbs. A comparison with TF joint data from the National Spherical Torus Experiment (NSTX) is also given. This will aid in deciding which jointing method to use for ST40 and the required pressure to pre-load the interface.

An air core pulse transformer with a linearly integrated primary capacitor bank to achieve ultrafast charging

An air core transformer that linearly integrates a capacitor bank as well as a selfclosing switch into the primary winding (LIP) was designed to achieve ultrafast charging. Limiting stray inductance and maximizing the uncoupled dual resonance of the primary and secondary windings were the primary design criteria. To show this concept, two transformers with an uncoupled resonant frequency of approximately 8 MHz were designed for a low voltage output (several kV) and a high voltage output (>100 kV). The design was simulated in a Multisim discrete circuit model and a CST hybrid model which includes the transformer's 3-D structure as well as discrete circuit components. The discrete output (voltage and current) as well as the distributed parameters (electric field distribution and surface current density distribution) for the transformer were obtained. These designs were validated by experimental results. We show that their respective resonance characteristic and voltage gain are accurately predicted by the simulated values, demonstrating the design procedure is valid for both low voltage and high voltage applications. For the high voltage transformer, it has a voltage gain of 3-4. The maximum output voltage was tested up to 120 kV. A charging pulse with a rise time of less than 100 ns was obtained.

A compact, high-voltage pulsed charging system based on an air-core pulse transformer

Charging systems of pulsed power generators on mobile platforms are expected to be compact and provide high pulsed power, high voltage output, and high repetition rate. In this paper, a high-voltage pulsed charging system with the aforementioned characteristics is introduced, which can be applied to charge a high-voltage load capacitor. The operating principle of the system and the technical details of the components in the system are described in this paper. The experimental results show that a 600 nF load capacitor can be charged to 60 kV at 10 Hz by the high-voltage pulsed charging system for a burst of 0.5 s. The weight and volume of the system are 60 kg and 600 × 500 × 380 mm(3), respectively.

Theoretical research of compact air-core pulse transformer for PFN-Marx generator repetitive charging

Theoretical research of compact air-core pulse transformer for PFN-Marx generator repetitive charging

Electrical Design and Operation of the Phelix Pulsed Power System

The Precision High Energy-Density Liner Implosion Experiment (PHELIX) is a pulsed power driver capable of delivering multimegampere currents to cylindrical loads. The PHELIX hardware includes novel design features to provide a high-energy conversion efficiency of approximately 10-MA output current per megajoule of stored energy. This is achieved by a rail-gap switched low-inductance Marx design (resistively damped) driving a multifilar air-core pulse transformer. The Marx output cables form the toroidal transformer that is an integral part of the disc line and removable load cassette assembly. The transformer and disc line uses conformal insulation methods and does not require replacement; after each shot, the transformer is completely reusable. Load cassettes can be easily exchanged to facilitate experimental variation. PHELIX is selfcontained within its own transport container and Faraday cage that can be moved from the maintenance building to the Los Alamos Neutron Science Center 800-MeV proton accelerator facility to perform multipulse proton radiography. This paper details the electrical and mechanical design of the Marx and multifilar transformer assemblies as well as presenting the operational performance achieved to date.

Simulation and Experimental Investigation of an Inductive Pulsed Power Supply Based on the Head-to-Tail Series Model of an HTS Air-Core Pulsed Transformer

The inductive energy storage for pulsed power supplies is considered to have a greater potential for high energy density than that of capacitive one. Therefore, it has practical applications in the industrial and military fields. Associating with the superconducting technology, this paper proposes an inductive pulsed power supply based on the head-to-tail series model of high-temperature superconducting air-core pulsed transformer. First, designed structure and working processes are analyzed in detail. Then, the simulated circuit model is built to illustrate the principles and characteristics using the software SIMPLORER. For verifying the feasibility of this pulsed power supply and gaining some experience in practical operation, a small-scale experiment is carried out with different delay times between two controlled switches. The experimental results show that large pulsed current with high energy transfer efficiency can be achieved by this model, which provides some guidance for future work.

Design and Experimental Realization of a New Pulsed Power Supply Based on the Energy Transfer Between Two Capacitors and an HTS Air-Core Pulsed Transformer

The application of pulsed power technology in the industrial and military fields requires a pulsed power supply as the large current generator. Based on theoretical analysis, it can be found that the traditional capacitor-based pulsed power supply may generate a large residual current during the discharging phase, which results in an adverse influence on the output current and energy transfer efficiency. To obtain higher energy transfer efficiency by eliminating the residual current, a new pulsed power supply based on the energy transfer between two capacitors and a high temperature superconducting (HTS) air-core pulsed transformer is proposed and a small-scale experiment is carried out under the different initial conditions. The experimental results show that a large pulsed current of 3.79 kA within 5 ms can be realized with the initial voltage 1.3 kV, whose energy transfer efficiency exceeds 65%. Finally, the feasibility of this new pulsed power supply is verified and it provides some guidance for future work.

Feasibility Research on Improving the Pulsed Current Output of Superconducting Inductor by Using HTS Air-Core Transformer

This paper aims to study the feasibility of improving pulsed current output by using High temperature superconducting (HTS) air-core transformer. Based on the theoretical analysis, the simulations are done. Results of the simulations indicate that the HTS air-core pulse transformer can magnify the output current magnitude and accelerate the velocity of discharge. However, when a series of inductor modules use the same one HTS air-core transformer, the residual current may influence the discharging waveform. To eliminate residual current, self-coupling discharging model is proposed. The simulated and experimental results illustrate that a self-coupling model can eliminate the residual current effectively. The results of this analysis contribute to the research of superconducting inductor pulsed current output.

脉冲大电流系统空芯变压器设计

In this paper, a strip air-core pulse transformer is designed to convert the current. And, how it works and the process of making iselaborated in detail. The transformer contains leads, insulator, copper strip and supporting core. Under the conditions of the charging voltage 2500 V, 5.52 kA and 1.48 kA peak current of primary and secondary windings are obtained, and correspondingly, the current rising rate is 37 A/s and 138 A/s. It is supported by analysis and experiment that the transformer can reduce the requirement of the rising rate of the switching current effectively. So, the thyristor can be used in the pulse current system which has a high current rising rate and improve its performance on repetition and stability.

Note: Compact high voltage pulse transformer made using a capacitor bank assembled in the shape of primary

The experimental results of an air-core pulse transformer are presented, which is very compact (<10 Kg in weight) and is primed by a capacitor bank that is fabricated in such a way that the capacitor bank with its switch takes the shape of single-turn rectangular shaped primary of the transformer. A high voltage capacitor assembly (pulse-forming-line capacitor, PFL) of 5.1 nF is connected with the secondary of transformer. The transformer output voltage is 160 kV in its second peak appearing in less than 2 μS from the beginning of the capacitor discharge. The primary capacitor bank can be charged up to a maximum of 18 kV, with the voltage delivery of 360 kV in similar capacitive loads.