High-temperature Superconducting Pulsed-power Transformer Research Articles

Experimental Study of Inductive Pulsed Power Supply Circuit With Residual Energy Recovery Branch

Inverse current commutation with semiconductor devices (ICCOS) has been proved to be able to shut off the high current of inductors. Inductive pulsed power supply (IPPS) is considered to have great potential in the field of Electromagnetic Launch (EML) due to its high energy density and fast discharge speed. A repetitive IPPS circuit with ICCOS technique has been proposed based on a high-temperature superconducting pulsed power transformer (HTSPPT) in our previous studies. This circuit can recover the remaining energy and generate continuous current pulses. However, due to the low voltage of the primary power supply, the circuit uses the primary power supply to recover the remaining energy, resulting in a slower process of recovering the remaining energy. For this issue, this article proposes a method to improve the original circuit by adding a residual energy recovery branch on the secondary side. The new circuit can recover most of the remaining energy on the secondary side through a designated capacitor. The working process of this circuit is illustrated detailed in this article, and the preliminary simulation verification is carried out. To further study the feasibility of this circuit, an experimental platform was built with a small HTSPPT. Experimental results and comparative analysis show that the new circuit has better characteristics in terms of remaining energy recovery and increasing pulse amplitude.

Modeling of the Rail Type Electromagnetic Launch System With Superconducting Pulsed Power Supply Considering Resistance

In the rail type electromagnetic launch system, when the projectile accelerates in orbit, it is affected by not only the electromagnetic force, but also various resistances, such as sliding friction, air resistance and so on. These resistances affect the characteristics of the pulsed power supply (PS). Nowadays, in order to analyze and design the pulsed PS conveniently, researchers usually ignore the influence of various resistors, and use fixed loads including resistors and inductors to simulate the rail load module, which will cause large errors. So, the mathematical model of the orbital electromagnetic launch system with superconducting is established, including the pulsed PS model with the multiple high-temperature superconducting pulsed power transformer (HTSPPT) and the dynamic rail load model considering various forces. The simulation results indicate that the dynamic rail load model considering various forces can reduce the error of capacitor voltage, load current and other parameters, the features of pulsed PS can be studied more precisely.

A Novel Repetitive Inductive Pulsed Power Supply Circuit With Residual Energy Rapid Recovery Branch

Due to the low electrical losses and low charging power requirements, the application of superconducting inductors in the inductive pulsed power supply (IPPS) for Electromagnetic Launch (EML) has great potential. In our previous studies, a repetitive IPPS circuit was proposed based on a high temperature superconducting pulsed power transformer (HTSPPT), which can recover the residual energy of the secondary circuit after each discharging phase and generate repetitive current pulses. However, when the load is an inductive load, such as augmented rail-type EML, the recovery p.rocess of residual energy will slow down. On this issue, this paper proposes a new repetitive IPPS circuit with residual energy rapid recovery branch. The remaining energy of the inductive load can be recovered by the capacitor in the proposed branch and can be provided to the load again in the next discharging phase. Simulations are carried out to illustrate this circuit. The results show that the proposed circuit has advantages in improving the amplitude of the output current pulse, shortening the fall time of the load current, and improving the effective energy utilization efficiency of the system.

Preliminary Analysis and Simulation of a 20-Hz Repetitive Superconducting Pulsed Power Supply

Superconducting pulsed power supplies (SPPSs) have attracted more and more attention because of their advantages of high energy storage density, long energy storage time, low loss, and low power requirements for charging power sources. In order to improve energy efficiency and output continuous pulse currents, a 20-Hz repetitive SPPS based on high temperature superconducting pulsed power transformer (HTSPPT) and residual energy recovery method is proposed and researched in this article. The main principle is that the residual energy is recovered and used for the next cycle of the repetitive SPPS for improving energy efficiency, shortening the charging time, and increasing the operating frequency. The working principle and procedure of the repetitive SPPS are introduced and analyzed in detail, and simulations are carried out to study the characteristics of the repetitive SPPS. The effects of the initial capacitor voltage and the switching trigger time of each cycle on the output characteristics are analyzed. The simulation results show that the repetitive SPPS with personalized trigger time can output a stable repetitive pulse current, that is, the output characteristics are stable.

Study on the operation mode of repetitive inductive pulsed power supply

Inductive hybrid pulsed power supplies (PPS) have attracted widespread attention in the field of electromagnetic Launch (EML). In our previous studies, a repetitive inductive PPS circuit topology based on a bridge-type capacitor switching circuit and a high-temperature superconducting pulsed power transformer(HTSPPT) was proposed. By using superconducting inductors, this circuit reduces the power requirements of the primary power supply. However, to prevent the charging current from exceeding the critical current of the superconducting inductors, the circuit must enter the discharging phase immediately when the charging current reaches the designated value, even the discharge time is inappropriate. On the issue, this paper proposes a new operation mode, which is inspired by the trickle charging of accumulators. In this mode, the circuit can keep working in the introduced trickle charging phase until the discharge pulse is required. To study the feasibility of this mode, a preliminary experiment was carried out based on an HTSPPT. The results show that the discharge time can be controlled by instructions and the proposed operation mode is feasible. In addition, the critical parameters and error control methods of the proposed operation mode are also analysed and discussed.

Arrangement Optimization of the Superconducting Pulsed Power Transformer of Inductive Pulsed Power Supply

High-temperature superconducting pulsed power transformer (HTSPPT) is an important component of superconducting pulsed power supply. Six superconducting coils and four normal conducting coils have been designed and manufactured in our previous work. The six superconducting coils and four normal conducting coils can be assembled into a large HTSPPT to obtain high energy storage. Five arrangement modes are proposed and analyzed in this paper. The self-inductance, coupling coefficient, magnetic field distribution and critical current of the five modes are obtained by finite-element simulation and calculation. The results show that Modes 1, 2, and 4 are feasible. Especially, Mode 1 has the highest coupling coefficient, the largest critical current, the highest energy storage capacity, the lowest capacitor voltage, and the shortest current rise time. As a result, Mode 1 is the best assembly sequence for the HTSPPT. The alternate arrangement of all primary and secondary coils can obtain the highest coupling coefficient and energy storage capacity.

Study of the electromagnetic characteristics of multiple HTSPPT modules based on the configuration of toroidal structure for inductive pulsed power supply

High temperature superconducting pulsed power transformer (HTSPPT) is an important device for pulsed power supplies. It consists of a superconducting primary and a normal conducting secondary, which is used for energy storage and current amplification. The critical current density, the energy storage, and the coupling coefficient are three main performance indexes. They are affected by the geometry parameters of HTSPPT modules, such as the height and the width of the superconducting coils. In addition, the hoop stress of the HTSPPT coils is limited by the maximum tensile strength of high temperature superconducting (HTS) tapes. In this paper, Bi-2223/Ag HTS tapes are selected as the wire of primary inductor and the toroidal structure model is selected for multiple HTSPPT modules. The relationships between the geometry parameters of HTSPPT modules and the electrical performance are studied.

Modeling and Simulation of Railgun System Driven by Multiple HTSPPT Modules

In the rail-type electromagnetic launching system, the equivalent load of pulsed-power supplies (PSs) varies with the launching process, while it has a certain influence on the discharge of pulsed PS. However, in the analysis and design of pulsed PS, researchers usually use the fixed resistance and inductance to simulate the load, which is impossible to accurately study the characteristics of the pulsed PS. The electromagnetic launching needs high-amplitude current pulse. Therefore, in this paper, a mathematical model of electromagnetic launching system driven by multiple superconducting inductive pulsed PS modules is established. In this model, the fixed resistance and inductance load are replaced by the dynamic load model of the railgun; the effects of dynamic load and fixed load on the discharge characteristics are analyzed; the parallel discharge characteristics of multiple high-temperature superconducting pulsed-power transformer (HTSPPT) modules are studied; and the characteristics of the simple rail-type electromagnetic launching driven by multiple HTSPPT modules are analyzed. The simulation results show that a high amplitude of current pulse can be produced using synchronous parallel discharge of multiple HTSPPT modules. The simulation results show that when the resistance and inductance of load are fixed at 2 $\text{m}\Omega$ and 0.5 $\mu \text{H}$ , respectively, the current amplification factor is 15.666, and the maximum voltage of the auxiliary capacitor is 1079 V. In the dynamic load model, the current amplification factor is 17.174, and the error is 9.6%. The maximum voltage of the auxiliary capacitor is 983 V, and the error is 8.9%. Therefore, the discharge characteristics of pulsed PS can be more accurately studied using dynamic models.

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.

Analysis and Exploiting of Mutual Coupling Effect on Inductive Pulsed Power Supply Consisting of Multiple HTS Pulse Power Transformers

Inductive pulsed power supply (IPPS) based on multiple high-temperature superconducting pulsed power transformer (HTSPPT) modules is a novel technology for electromagnetic launching. In a compact multimodule IPPS, the mutual couplings between HTSPPT modules are unavoidable. In this paper, an IPPS with the method of improved pulse-forming process which proved to be feasible by preliminary experiment is proposed to analyze the effect of the mutual couplings. The characteristics of the mutual coupling effect on the IPPS are presented in detail by theoretical analysis and parametric simulations. The evaluation indices reflecting performances of the IPPS under the mutual coupling effect are derived from simulations, including the energy storage capacity, flux linkage, axial tensile force, output current amplitude, and so on. Parametric simulations are executed with respect to the module arrangement, the number of modules, and the arrangement radius. Finally, the analysis of mutual coupling effect is summarized, and a strategy for exploiting mutual couplings between modules is put forward to improve IPPS performance.

A Zero-Current Opening Circuit for Inductive Pulsed-Power Supply Based on High-Temperature Superconducting Pulsed-Power Transformer

The opening switch is one of the critical technologies in the development of inductive pulsed-power supply. The power requirement is very high when the opening switch is desired to commutate a large current. This paper presents a zero-current opening circuit for inductive pulsed-power supply based on a high-temperature superconducting pulsed-power transformer. First, there are two types of current flowing through the opening switch, one comes from the secondary side of the pulse transformer, and the other one comes from superconducting energy storage inductance. The orientation of the two current is opposite. Then, when the current flowing through the opening switch closes to zero, the switch is opened and this restrains the over-voltage pulse of the opening switch. The simulation results indicate that this zero-current opening circuit is feasible and has potential applications for high-energy systems in the future electromagnetic launcher.

An Inductive Pulsed-Power Supply Circuit Consisting of Multiple HTSPPT Modules With Capacitor Reuse Methodology

Superconducting pulsed-power supply (SPPS) provides an efficient method for both high-density inductive energy storage and high current pulse generation. An SPPS consisting of eight high-temperature superconducting pulsed-power transformer (HTSPPT) modules with XRAM methodology was designed and simulated in preliminary studies. It recycled the leakage flux energy and reduced the voltage across the opening switch with a capacitor in primary. However, the SPPS with XRAM methodology has two problems. The first one is that it can provide high pulse amplitude, but cannot provide enough width. The other one is that the ratio of the maximum capacitive energy over the total inductive energy is relatively large, which cuts down the overall system energy density. This paper proposes a modified topology of SPPS with capacitor reuse methodology. Multiple HTSPPT modules are divided into several groups. Each group shares the same capacitor. The procedure of the modified SPPS is presented in detail. A 270-kJ SPPS with capacitor reuse methodology is designed and simulated to illustrate the modified topology. With the load parameters of a small railgun, the peak value of the load current is 207.15 kA and the pulse half-height width is 5.56 ms, the ratio of the maximum capacitive energy over the total inductive energy is 11%. The characteristics of the modified topology are also described in detail in this paper.

Influence of Critical Parameters on the Performance of a Superconducting Inductive Pulsed-Power Supply Circuit

The superconducting inductive pulsed-power supply (SPPS) circuit consists of a high-temperature superconducting pulsed-power transformer (HTSPPT) and an auxiliary capacitor. The electrical losses and the power of the primary source can be cut down with the superconducting inductive energy storage. Although its energy density is slightly less than a purely superconducting inductive system, it can reduce the maximum voltage of the opening switch by the capacitor and achieve a high degree of current amplification factor. However, during the discharge process, the magnetic leakage flux energy stored in the primary of the HTSPPT requires the capacitor to have a certain capacity. The higher the ratio of the capacitive stored energy over the total inductive stored energy, the more the dominant position of inductive energy storage reduces. The current amplification factor (γ), the maximum voltage of the opening switch (V Smax ), and the ratio of capacitive stored energy (η) are the three main properties of the SPPS circuit, which depends on several intertwined critical parameters, such as the inductance ratio n = L 2 /(L 2 + LL) and the capacitance (C 1 ). This paper studies the influence of the critical parameters on the main circuit performance with a 1-kJ SPPS system. The detailed selection method of the critical parameters for the specific system is also discussed with a coupling coefficient of 0.95. Such a system is easy to be utilized for the basic experimental study of a small railgun.

A modified circuit topology for inductive pulsed power supply based on HTSPPTs

High temperature superconducting pulsed power transformer (HTSPPT) provides an efficient method for inductive energy storage and current multiplication. The primary inductor of HTSPPT used for energy storage is made of high temperature superconducting coils, and the secondary inductor used for current pulse generation is made of normal conductor coils. In the initial circuit, the secondary inductor generates current pulse by switching out the coupled primary superconducting inductor. However, during the switching period, the leakage flux caused by imperfect coupling and the sudden change in primary current induce a voltage across the opening switch which exceeds the affordability of modern solid-state switches. In previous studies, a half-cycle oscillatory discharge circuit is proposed to mitigate these problems by using a capacitor to recapture the energy in the leakage flux and to slow down the turnoff of current in the primary. However, there are still some problems should be settled. For example, the output pulse cannot be adjusted, the residual energy cannot be recovered and the capacitor branch circuit may have an impact on the charging process. In the paper, a modified discharge circuit topology is introduced to solve these problems. A multi-module system comprising of several HTSPPTs charging in series connection and discharging in parallel is also designed and simulated. This system can be used to power an electromagnetic emission device.

Experimental Study of Inductive Pulsed Power Supply Based on Multiple HTSPPT Modules

For electromagnetic emission applications that need a very high amplitude and an appropriate pulsewidth, a pulsed power supply based on multiple high-temperature superconducting pulsed power transformer (HTSPPT) modules is verified in this paper. First, the working processes of multiple HTSPPT modules are analyzed and two small experimental HTSPPTs are described in detail. Then, simulation is carried out to show the major pulse characteristics of two different discharge methods. To verify the feasibility of two discharge methods, high-current testing is carried out with the two HTSPPTs. The results show that a higher amplitude of current pulse can be achieved using synchronous parallel discharge and a larger pulsewidth of current pulse can be achieved using asynchronous parallel discharge.

Design and Testing of a High-Temperature Superconducting Pulsed-Power Transformer

This paper presents the design process and test results of a high-temperature superconducting pulsed-power transformer (HTSPPT). The primary winding of the HTSPPT is constructed out of several double-pancake-type coils connected in series. Every double-pancake-type coil is made of Bi2223/Ag tapes. The secondary winding is constructed out of several single-pancake-type coils made of normal conductors. The configuration of the HTSPPT is designed such that the primary and secondary coils are arranged in interleaving. The testing experiments show that a high-current impulse could be achieved with a small current in the primary, which proves that the designed test circuit and the configuration of HTSPPT are feasible.