Search

In inductive pulsed power supplies (IPPSs), the toroidal circular disk-type inductors have the advantages of high energy density, good symmetry, and slight magnetic field interference. However, the inductance calculation of the toroidal coils with a different geometric structure and electrical connection is very complicated, let alone the overall optimization of the IPPS system using structure parameters as variables. In this article, a systematic quick calculation method for the toroidal circular disk-type inductor with any geometric structure and electrical connection has been summarized and elaborated. Some improvements in accelerating the calculation speed have been proposed and verified. The error between the proposed calculation method and measurement is less than 1.1%. Finally, with the quick calculation methods, the genetic algorithm (GA) is used to optimize a 20-stage inductor for an XRAM generator with a total energy of 1.25 MJ. After 12 400 calculations, the energy density of the obtained optimal toroidal coil reaches 14.54 MJ/m3. [ABSTRACT FROM AUTHOR]

Inductive pulsed power supply (IPPS) is a competitive type of power supply for electromagnetic launch (EML). Compared with the capacitive type, the structure and working process of IPPS are more complicated, which make the design of the IPPS module difficult. In this article, the method of calculating the module performance from structural and electrical parameters is proposed. Based on that, the biobjective optimization of a 100-kJ module is carried out. With the help of genetic algorithms, the optimization results are 2500 nondominated solutions on the Pareto front, and one of the representative solutions is verified by experiments. The performance of the built module is in good agreement with the calculated value. Its energy density reaches 3.98 MJ/m3, the peak output current reaches 23 kA with 8.1-ms pulsewidth. [ABSTRACT FROM AUTHOR]

High energy density makes inductive pulsed power supply (IPPS), a research focus of supplies for electromagnetic launch (EML). However, in existing IPPS topologies, the charging and discharging stages of the inductors cannot be separated, so the response time of IPPS can be as long as ten or even tens of milliseconds. For this reason, the real-time closed-loop control of the output current and muzzle velocity based on IPPS is nearly impossible, which might be one of its biggest drawbacks compared to the capacitive pulsed power supply (CPPS). In this article, a novel current maintainable meat grinder (CMMG) circuit capable of fast response for EML applications is proposed, in which the antiparallel diode can provide a current maintaining path. After the inductor completes its charging process, the current can be maintained for a period of time. Thus, the circuit can be in a hot standby state and can be triggered with a very short delay. Subsequently, two commutation methods for the CMMG circuit are explored. The first one is to introduce the inverse current commutation with semiconductor device (ICCOS) branch. In its experiment with an inductance energy of 22 kJ, the circuit maintains 77% of the charging energy in the first 10 ms and is triggered successfully after 28 ms with almost zero response delay. The second method is the superconducting switching technology, based on which the CMMG with self-shutdown circuit is proposed and simulated. [ABSTRACT FROM AUTHOR]

The performance of inductive pulsed power supplies (IPPSs) is limited by excessive joule heat loss and low energy transfer efficiency. A significant reduction in the coil resistance can fundamentally ameliorate this problem. This article takes the meat grinder with self-charge capacitor and thyristor (SECT) circuit as an example to study the performance improvement caused by the reduction of the coil resistance. The influence of coil resistance on several performance indexes is analyzed by circuit analysis and simulation. Then, the experiment with an energy level of 40 kJ is carried out, in which the inductors have very low resistance due to immersion in liquid nitrogen. With low temperature, the charging energy and the output current peak value are increased by 37% and 19%, respectively, the pulsewidth of output current is increased by 257%, and the energy transfer capacitor is successfully self-charged compared to the performance of the same SECT circuit with room temperature. Thus, the feasibility of applying nitrogen cooling to IPPS is validated. [ABSTRACT FROM AUTHOR]

A novel circuit with the better performance for the inductive pulsed power supplies in the electromagnetic launch system is proposed in this paper, namely, the meat grinder with capacitive pulse forming unit (CPFU). Its working process is qualitatively analyzed stage by stage. Its practical feasibility is verified through a 7.5-kJ experiment. From the perspectives of circuit structure and working principle, this circuit can be regarded as the combination of a meat grinder and a CPFU. Compared with its preceding circuits, this circuit possesses following advantages: 1) the self-recovery of the capacitor precharged voltage can easily be achieved, which is conducive to continuous operations of the whole circuit and 2) the waveforms of the inductor currents contain no capacitive components, which can promote the energy storage density of the inductors. [ABSTRACT FROM PUBLISHER]

The meat grinder is a basic circuit for inductive pulsed-power supply (IPPS). Based on meat grinder, the Institute of Advanced Technology proposed a circuit called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder, in which an Integrated Gate Commutated Thyristors (IGCT) is selected as the main switch. Tsinghua University proposed the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS) in which the main switch is replaced by a thyristor and the ICCOS subcircuit is introduced to turn off the main switch. To reduce the opening switch voltage and increase the current turning-off capacity for IPPS, this paper presents a novel circuit topology named the meat grinder with self-charged capacitor and thyristors (SECTs). The key idea of the SECT topology is to turn off the primary current by the energy transfer capacitor, which is precharged. The meat grinder with SECT has larger capacity than the STRETCH meat grinder because it replaces the IGCT with a thyristor and is simpler than the STRETCH meat grinder with ICCOS because it only needs one capacitor. The suggested circuit is more suitable for IPPS module with high energy density. Simulation and experiment have been carried out to validate the circuit. [ABSTRACT FROM PUBLISHER]

Because it possesses higher current turn-off capability, the inverse current commutation with semiconductor devices (ICCOS) is a better option for the opening switch of an inductive pulsed power supply than the integrated gate commutated thyristor. This paper investigates the counter-current capacitor, which is the key component that determines the turn-off result and the volume of the counter-current branch. The major contributions of this paper include the following: 1) deriving an analytical expression for the minimum precharged capacitor voltage that can reliably turn off the main switch; 2) verifying this expression through a series of experiments within a current range of 0 to 4000 A and an energy range of 0 to 50 kJ; 3) giving an approximate expression for the optimal capacitance that minimizes the precharged energy; and 4) investigating the variation trends of the optimal capacitance and the corresponding optimal precharged energy with varying inductor current. [ABSTRACT FROM PUBLISHER]

The major strengths of inductors in energy density and power density make an inductive pulsed power supply (IPPS) a promising option for pulsed power supplies in an electromagnetic launch system. Among the circuits for an IPPS, the capacitor-aided meat grinder circuits constitute an important branch. An analytical method for the working processes of these circuits is proposed in this paper. The core of this method is the decoupling of a high-order circuit into the superposition of a resistor–inductor first-order equivalent subcircuit and a resistor–inductor–capacitor second-order equivalent subcircuit. The validity and accuracy of this method have been verified through comparison with a numerical simulation. The results show that this method possesses both satisfactory accuracy and excellent computational speed. With the same circuit parameters and time step, the time cost of this method is three orders of magnitudes lower than the time cost of a numerical simulation. Moreover, this method contributes to more intuitive understanding and more essential insight into the working principles of the capacitor-aided meat grinder circuits. [ABSTRACT FROM PUBLISHER]

The meat grinder with SElf-charged Capacitor and Thyristors circuit is a novel circuit for inductive pulsed power supplies. The energy transfer capacitor is one of the key components in this circuit. And its capacitance C and the precharged voltage UC are key parameters worth investigating. The circuit working process and corresponding numerical calculation method are briefly introduced. And the method validity is verified through experiments. Then, the influences of $C$ and UC on circuit performance indices, i.e., the maximum voltage across the main switch $V_{{\mathrm{sopm}}} , the secondary current multiplication factor m2 , the ratio of the maximum capacitor energy over the inductor charging energy \eta C , and the self-recovery rate of the precharged capacitor voltage k\mathrm{UC} , are quantitatively analyzed through parameter sweep. Generally speaking, large C is conducive to lower $V_{{\mathrm{sopm}}} ; small m2 ; small C and low UC are conducive to lower \eta C and higher $k_{{\mathrm{UC}}}$ . Moreover, the analytical expression of $k_{{\mathrm{UC}}}$ is given. With C and UC elaborately selected, $k_{{\mathrm{UC}}}$ can achieve 100%. In addition, the balance relationship between two contradictory indices $V_{{\mathrm{sopm}}}$ and $k_{{\mathrm{UC}}}$ is obtained by solving a biobjective optimization problem and using the genetic algorithm. [ABSTRACT FROM AUTHOR]

With inherent strengths in energy density and power density, the inductive pulsed power supplies (IPPS) have become an attractive option for the power supplies in electromagnetic launch systems. The meat grinder circuits, including the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit, the STRETCH meat grinder with inverse current commutation with semiconductor devices circuit, and the meat grinder with self-charged capacitor and thyristors circuit, constitute one major branch among the IPPS circuits. This paper summarizes the fundamental research work and contributions of the meat grinder circuits from the perspectives of circuit improvements, performance analysis, inductor design, module collaboration, and efficiency promotion. The future directions of single IPPS module are higher energy level, larger energy density, and higher efficiency. [ABSTRACT FROM PUBLISHER]

Based on the urgent needs for modularization and miniaturization of the inductive pulsed power supply system, this paper proposes the conceptual design and comparison of 100-kJ inductive storage power modules including four circuit topologies, three of which are proposed in our previous researches. The four circuit topologies are the STRETCH meat grinder, the XRAM with STRETCH meat grinder unit, the XRAM with strongly coupled inductors, and the XRAM with magnetic flux compression effect. The maximum load current of each constructed module is set to be 50 kA and its pulsewidth is at least 5 ms, which are the same as the main electrical properties of an existing 100-kJ capacitive module. A comparative study on energy density among the constructed inductive modules and the existing capacitive module is carried out in depth. Results show that the inductive modules, considering the volume of semiconductor switches and their control circuits, have higher energy density than that of the capacitive module. Among four constructed inductive modules, the XRAM with strongly coupled inductors module has the highest inductive energy density, and the XRAM with magnetic flux compression effect module has relatively better comprehensive performance. This paper offers the theoretical analysis foundation for investigating the inductive pulse power supply with higher energy. [ABSTRACT FROM PUBLISHER]

The dual representation of MARX (XRAM) pulse current generator with magnetic flux compression effect is a novel circuit for current multiplication, which has the advantages of both meat grinder and XRAM that are basic circuit topologies. It contributes to the multiplication of current in two aspects: first, increasing current by magnetic flux compression and second, the current can be increased by paralleled inductors. Compared with the standard XRAM topology, the proposed circuit topology can realize a larger factor of current multiplication more easily, and is better than the standard slow transfer of energy through capacitive hybrid meat grinder circuit topology in aspects of scalability and modularity. Meanwhile, its energy density is increased significantly, which is advantageous to the needs of actual electromagnetic launch. In this paper, theoretical analysis is done to illustrate the excellent performance of the proposed topology and preliminary experiment was conducted to demonstrate its feasibility. [ABSTRACT FROM PUBLISHER]

The air-core flat spirals of strip coil structure is a typical type of the tightly coupled energy storage inductors used in inductive pulsed power supplies. This paper improves the speed and the parameter scope of the inductance calculation method for these inductors. Specifically, the analytical expressions using the structural parameters to represent the performance parameters, e.g., the inductance, the resistance, and the current conducting capability of the primary inductor and the secondary inductor L1 , L2 , R1 , R2 , I\mathrm{ 1limit} , I\mathrm{ 2limit} , the total volume V\mathrm{ tot} , and the energy density \omega , are given. The validity of this method is confirmed by practical measurements of a set of constructed inductors with 2.67-mH total inductance. The absolute error is within 0.02 mH. On the basis of this method, parameter optimization on energy density is conducted for the 70-kJ energy level module. Results show that the energy density can reach 11.2 MJ/ \text{m}^{3} when the total inductance is 5.07 mH and the total volume is 6.3\times 10^{-3}~\text{m}^{3}$ . [ABSTRACT FROM AUTHOR]

The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder circuit is a widely used topology in inductive pulse power supply. Therefore, it is important to understand the relationship between the STRETCH meat grinder performances and the inductor parameters when improving the system performance and designing the inductor. From the perspective of inductor designing, this paper uses four indicators to present the STRETCH meat grinder performances, i.e., the charging current, the current amplification, the inductor energy density, and the discharge efficiency, and uses two indicators to present the inductor parameters, i.e., the total inductance and the ratio of the inductance L1 to L2 . First, the meanings of the indicators are explained or defined. Second, simulations and experiments are carried out, respectively, to analyze the trends of the four performance indicators along with the changes of two parameters indicators. Finally, both simulation and experiment results show that the increase of the total inductance leads to the decrease of the charging current and the discharge efficiency; moreover, the increase of the ratio of the inductor L1 to L2 leads to the increase of the current amplification and the discharge efficiency, but causes the decrease of the inductor energy density. [ABSTRACT FROM AUTHOR]

To improve the efficiency of inductive pulsed power supplies (IPPS), liquid-nitrogen (LN2) cooling has been recommended to limit the energy loss. However, the low-temperature environment not only significantly reduces the resistances of the inductors but also slightly reduces their inductances. To fully evaluate the overall impacts of low temperature, eight performance indices are proposed, i.e., charging time T0 , efficiency \eta , primary/secondary current multiplication ratio m_{1}/m_{2} , ratio between the maximum capacitive energy and the total inductive energy \eta _{C} , maximum voltage across the main switch U\mathrm{ Sopm} , muzzle velocity proportional term \propto {v} , and total energy loss caused by the inductors’ internal resistance ER . Using the typical slow transfer of energy through the capacitive hybrid circuit topology as an example, a semianalytical parametric analysis method is proposed to analyze this multiparameter problem. The results indicate that whether indices m1 , \eta C , and U\mathrm{ Sopm} will be improved or worsened after adopting low temperature depends on specific system parameters, while the other five indices will be improved for any inductor and system parameter. Furthermore, by using a theory of equivalent inductance, the results are explained qualitatively. A test platform that introduces the LN2 cooling is established for verification, and the results agree well with the theory. The proposed semianalytical method can also be extended to any time subsection circuit topologies of IPPS for the performance analysis. [ABSTRACT FROM AUTHOR]

Paralleled pulse-forming units (PFUs) with different triggering delays might be a paramagnetic way for generating flat-topped current wave for electromagnetic launch. Many researchers have reported that multiple capacitive storage PFUs were implemented such current waves in laboratories. However, due to its low energy density, the applications of the capacitive pulsed-power supplies are limited. Since the inductor has advantages in energy density, the inductor pulsed-power supply becomes one of the hottest topics recently. The slow transfer of energy through capacitive hybrid meat grinder with inverse current commutation with semiconductor devices proposed by Tsinghua University has demonstrated its advantage and applicability recently. Using this kind of topology, this paper proposes the design of an inductive storage PFU with a stored energy of 100-kJ. The maximum load current reaches to 50 kA and its pulsewidth is at least 5 ms. The optimized inductive storage PFU shows superiority in contrast to the capacitive storage PFU with the same energy. This paper offers the theoretical analysis and the testing foundation for investigating the inductor pulsed-power supply with higher energy. [ABSTRACT FROM PUBLISHER]

The energy density of the inductive energy storage systems is one order of magnitude higher than that of the capacitive ones. The slow transfer of energy through capacitive hybrid (STRETCH) meat grinder with inverse current commutation with semiconductor (ICCOS) devices put forward by Tsinghua University is a typical inductive pulsed-power supply for electromagnetic launch system, which has remarkable current amplification ability as a single module. However, one module cannot provide enough amplitude and width for the load current of the railgun launching. Therefore, the collaborative work of multiple inductive source modules is necessary for practical usage. In this paper, the designed inductive power supply system of about 1 MJ is composed of 40 STRETCH meat grinders with ICCOS modules. All the main switches are opened simultaneously to reduce the magnetic field coupling among the modules and make the current rising edge steep. The modules are divided into several groups. The triggering delays of the thyristors between every two adjacent groups are carefully designed. After the first triggers for all the modules, the energy stored in the capacitors can be further utilized with the second triggers. The numerical simulation results show that the appropriate collaborative triggering delay can increase the adjustability of the output current width and the second triggers can further increase the current width and the system efficiency. Therefore, the load current with flat shape, appropriate amplitude, and longer duration can be provided with modular design and collaborate triggering discharge of the multiple modules. This can provide a theoretical foundation for the future study and implementation. [ABSTRACT FROM PUBLISHER]

By applying the principle of inverse current commutation with semiconductor (ICCOS) devices in a slow transfer of energy through capacitive hybrid (STRETCH) meat grinder system, a novel circuit topology called STRETCH meat grinder with ICCOS was proposed by the Tsinghua University in 2013. It can not only raise the amplitude of the opening current, but also reduce the cost of the STRETCH meat grinder circuit obviously by replacing the integrated gate-commutated thyristor (IGCT) with thyristor. This paper discusses the overall design, system implementation, and testing results of a STRETCH meat grinder with ICCOS system with roughly 1-kJ inductive energy. The load is a spiral coil with 1.4- \textm\Omega resistance and 1.4- \mu \textH inductance. With closed-loop control strategy, the system detects the charging current of the inductors. When it reaches the designated value, the triggering signal for ICCOS is delivered and after the predefined delay time, the triggering signal for discharging the voltage on the pulse-forming capacitor is delivered. The current of the inductors and the load are measured by Rogowski coils. The opening current is 1 kA and the maximum load current is close to 4 kA. All the voltages on the switches are lower than 1 kV. The experimental results are consistent with the simulated ones, which verified the correctness of the theoretical analysis and proved the applicability of the STRETCH meat grinder with ICCOS for larger energy level. [ABSTRACT FROM PUBLISHER]

The STRETCH meat grinder is one typical inductive pulsed-power supply topology for electromagnetic launch system. It has remarkable current amplification ability as a single unit, but one module cannot provide enough amplitude and width for the load current of the railgun launching. This paper discusses the effects of different triggering delays on the load current with two STRETCH meat grinder modules. To reduce the magnetic field coupling between the two modules, the two main switches are opened simultaneously. To make the load current waveform with no notch, the thyristor of the first module is triggered when its pulse-forming capacitor is fully reversely charged. For the thyristor of the second module, we consider several time points of triggering delay. Because of the practical constraint for the maximum rail current that ensures no rail erosion, the rectangular waveform is the most appropriate load current waveform. Therefore, the comparing criterion can be defined as the ratio of the load current waveform area and its maximum rectangle area at different current levels. Higher ratio means that the current is more like a rectangular wave and is better accordingly. Based on the above criterion and extensive simulation research, we found that the best delay time is the moment when the capacitor is reversely charging the inductor completely. This paper and the result are of great theoretical significance for the further study on the collaborative triggering of multiple STRETCH meat grinder modules. [ABSTRACT FROM PUBLISHER]

Structural parameters directly affect the energy density and the total resistance of the inductors used in inductive pulse power supply (IPPS). This paper elaborates the relationship between the structural parameters and electrical performances of the inductors used in IPPS and set up the inductors for the experiment in slow transfer of energy through capacitive hybrid meat grinder circuit using air-core flat spirals of strip coil. Then we compile a program that can obtain the structural parameters of the inductors that have the highest energy density under the condition of given charging and discharging currents as well as inductances in the primary and secondary sides. The calculation results of the program are analyzed and verified by the measured values of the real inductors. At the end, on the condition of a constant current density, we put forward a rule that along with the increase in the system energy, the energy density of the IPPS became higher and the resistance of the inductors became lower. [ABSTRACT FROM PUBLISHER]

Inductive pulse power supplies are of interest because their energy densities are one order of magnitude higher than those of capacitive power supplies, based on the same power-output capacity. The Institute of Advanced Technology puts forward an inductive pulse power topology called the slow transfer of energy through capacitive hybrid (STRETCH) meat grinder. In this topology, an active switch is used to cut off the charging current. Limited by the current turning off ability of integrated gated commuted thyristor, it may encounter difficulties in extending to higher-energy systems. Other than that, the cost of the system is very high. In this paper, the principle of the STRETCH meat grinder is presented. Then, the STRETCH meat grinder with inverse current commutation with semiconductor devices (ICCOS), which is proposed by the Institute of Saint Louis, is presented. The process of ICCOS in the STRETCH meat grinder is illustrated in detail. Finally, simulations are made based on Simplorer 8 to explain how ICCOS works clearly. A preliminary discussion of how to design ICCOS is also presented. We conclude that the STRETCH meat grinder with ICCOS removes the limitations of the original one and has potential applications for high-energy systems in future and can cut down the cost greatly. [ABSTRACT FROM PUBLISHER]