Inductive Storage Research Articles

An active filter with inductive storage for compensation of inactive power of a rectifier with a capacitive filter

Compensation of the inactive components of network current of a rectifier with a capacitive filter or a combination thereof under connection of a parallel active filter with inductive storage based on a current inverter is considered. The active filter allows increasing the power coefficient to the maximum values, and this result may be achieved at high values of storage inductance. Modeling of the “rectifier–active filter” system is carried out by spectral methods. It is shown that correction of the switching algorithm by storage-current feedback provides a decrease by three to four times of inductance at the same values of the power factor of the “rectifier–active filter” system. A multistage active filter consisting of a current inverter and voltage inverter with current stabilization on the direct current is proposed. The total cost for the inductive elements in the multistage active filter may reduced by one order with the same values of power factors. Comparison of voltage inverters based on bridge and half-bridge schemes is carried out. Advantages of half-bridge inverters are shown.

Pulse generator with intermediate inductive storage as a lightning simulator.

Compact transportable generators are required for simulating a lightning current pulse for electrical apparatus testing. A bi-exponential current pulse has to be formed by such a generator (with a current rise time of about two orders of magnitude faster than the damping time). The objective of this study was to develop and investigate a compact pulse generator with intermediate inductive storage and a fuse opening switch as a simulator of lightning discharge. A Marx generator (six stages) with a capacitance of 1 μF and an output voltage of 240 kV was employed as primary storage. In each of the stages, two IK-50/3 (50 kV, 3 μF) capacitors are connected in parallel. The generator inductance is 2 μH. A test bed for the investigations was assembled with this generator. The generator operates without SF6 and without oil in atmospheric air, which is very important in practice. Straight copper wires with adjustable lengths and diameters were used for the electro-explosive opening switch. Tests were made with active-inductive loads (up to 0.1 Ω and up to 6.3 μH). The current rise time is lower than 1200 ns, and the damping time can be varied from 35 to 125 μs, following the definition of standard lightning current pulse in the IEC standard. Moreover, 1D MHD calculations of the fuse explosion were carried out self-consistently with the electric circuit equations, in order to calculate more accurately the load pulse parameters. The calculations agree fairly well with the tests. On the basis of the obtained results, the design of a transportable generator was developed for a lightning simulator with current of 50 kA and a pulse shape corresponding to the IEEE standard.

Active vehicle battery balancing scheme in the condition of constant-voltage/current charging and discharging

This paper presents a battery-equalization circuit and its control strategy. Energy storage inductors are applied in the circuit and their number is less than that of the switches. The topology is simple and easy to control. The antiparallel diode of the power switches can provide freewheeling path of the inductance current, and the energy can be transferred by switching. Battery charging and discharging has constant-voltage and constant-current mode. The corresponding control strategies of the equalization circuit are different. The working principle is discussed and the control strategies in the conditions of constant-voltage and constant-current modes are analyzed. The simulation model of the active battery-equalization scheme and an equalization circuit combined with the battery management system are established. Also a comparison is made to the existing inductor-based equalization schemes. The simulation and experimental results verify the theoretical analysis. The proposed battery-equalization scheme can realize the expected effect.

Output Voltage Control and Efficiency Improvement of Multistage Impulse Voltage Generator by Utilizing Inductive Energy Storage

SUMMARYIn this paper, we propose two control methods of a static impulse voltage generator to lower the influence of dc voltage source fluctuations on the output voltage and to improve its efficiency by reusing discarded inductive storage energy. Introducing output voltage control adjusting the charging period of capacitive and inductive energy in accordance with the source voltage, the output voltage fluctuation by the source voltage decreased by 61.1%. Applying the reusing method, we estimated by circuit simulation that the amount of energy that could be recovered was 21.0% and the efficiency of energy transfer was improved from 60.4% to 76.7%.

A 50 kJ Inductive–Capacitive Storage Module With Solid-State High-Power Opening Switch Based on Counter-Current Thyristor

This paper describes a compact high storage density inductive-capacitive storage module. The module is based on high-power opening switches using inverse current commutation with semiconductor devices commutation principle and a high storage density Brooks inductor. These opening switches, being able to switch-OFF pulse currents up to 14.5 kA by the countercurrent subcircuit, make use of the general property of a standard high-power thyristors impedance transition from closing state to blocking state. The experimental results show that with the primary capacitor and counter-current commutation subcircuit charged voltage 3 and 2.5 kV, respectively, the charged current of the Brooks-type inductor is about 14.5 kA, with a charged time of about 4.5 ms. The output peak current of the inductive storage module is about 21 kA. The total stored energy is about 54.9 kJ while the energy density of the inductor is approximately 6.69 MJ/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> , which is not including the primary storage and commutation unit.

Parameter Analysis and Optimized Configuration of the PFU for Inductive Storage Systems

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.

Plasma instability in fast spherical discharge induced by a preionization

As it was shown earlier, fast discharge (dI/dt ∼ 1012 A/s and Imax ≈ 40 kA) in a spherical cavity (Al2O3, inner diameter 11 mm, 4 mm apertures for the current supply) filled with working gas (Ar and Xe, pressure 80 Pa), results in the formation of a plasma with the form close to spherical. The physical mechanism can be the cumulation of a convergent shock wave, which was originated near the inner surface of the discharge cavity. It was also shown for the cylindrical fast discharge that the preionization influences the dynamics of the cylindrical convergent shock wave, its evolutions becomes faster. The present work is devoted to the study of the influence of the preionization on the plasma formation in the fast discharge with spherical geometry (Ar, 80 Pa). The inductive storage with plasma erosion opening switch was used as a current driver. The spatial structure of the discharge plasma was studied by means of a pin-hole camera with the microchannel plate (MCP) detector with time gate of 5 ns. The extreme ultra violet spectra were studied by means of the grazing incidence spectrometer with the same MCP detector with time gate of 20 ns. Beside the expected effects (reduction of the spherical plasma formation time and some increase of the electron temperature), the preionization of the discharge by the current 500 A results also in the development of the plasma instabilities and destruction of the compact plasma ball in several tens of nanoseconds. Possible mechanism of the instability is discussed.

Decoupling of Fluctuating Power in Single-Phase Systems Through a Symmetrical Half-Bridge Circuit

Single-phase ac/dc or dc/ac systems are inherently subject to the harmonic disturbance that is caused by the well-known double-line frequency ripple power. This issue can be eased through the installation of bulky electrolytic capacitors in the dc link. Unfortunately, such passive filtering approach may inevitably lead to low power density and limited system lifetime. An alternative approach is to use active power decoupling so that the ripple power can be diverted into other energy storage devices to gain an improved system performance. Nevertheless, all existing active methods have to introduce extra energy storage elements, either inductors or film capacitors in the system to store the ripple power, and this again leads to increased component costs. In view of this, this paper presents a symmetrical half-bridge circuit which utilizes the dc-link capacitors to absorb the ripple power, and the only additional components are a pair of switches and a small filtering inductor. A design example is presented and the proposed circuit concept is also verified with simulation and experimental results. It shows that at least ten times capacitance reduction can be achieved with the proposed active power decoupling method, and both the input current and output voltage of the converter can be well regulated even when very small dc-link capacitors are employed.

Conversion of high explosive chemical energy into energy of powerful nanosecond high-current pulses

This study is a contribution into the development of physicotechnical foundations for generation of powerful nanosecond high-current pulses on the basis of explosively driven magnetic flux compression generators. This problem is solved by using inductive storage of energy for matching comparatively low-voltage explosively driven magnetic flux compression generators and high-impedance loads; short forming lines and vacuum diodes. Experimental data of charging of forming lines are given.

Transportable High-Energy High-Current Inductive Storage GW Generator

A number of high-power applications require a transportable high-energy, high-current GW generator to drive a pulsed power system at the output. A first prototype, based on exploding wire technology and using an H-bridge circuit configuration, was developed at Loughborough University a few years ago and has been previously reported. The present stage of the work has necessitated the development of a more powerful and energetic source, and this is now based on inductive storage technology. A 400 kJ capacitor bank is connected by a high-Coulomb explosively driven closing switch with an air-cored 0.6 MV transformer, an exploding wire array, and a high-power diode based on a polarity-dependent spark-gap completing the arrangement. The GW generator, including the command and control module, is accommodated in two ISO containers. The various components of the generator are described in this paper, together with results obtained from full-scale tests.

Variable Off-Time Control Loop for Current-Mode Floating Buck Converters in LED Driving Applications

A versatile controller architecture, used in current-mode floating buck converters for LED driving, is developed. State-of-the-art controllers rely on a fixed switching period and variable duty cycle, focusing on current averaging circuits. Instead, the proposed controller architecture is based on fixed peak current and adaptable off time as the average current control method. The control loop is comprised of an averaging block, transconductance amplifier, and an innovative time modulator. This modulator is intended to provide constant control loop response regardless of input voltage, current storage inductor, and number of LEDs in order to improve converter applicability for LED drivers. Fabricated in a 5 V standard 0.5 $\mu\hbox{m}$ CMOS technology, the prototype controller is implemented and tested in a current-mode floating buck converter. The converter exhibits sound continuous conduction mode (CCM) operation for input voltages between 11 and 20 V, and a wide inductor range of 100–1000 $\mu \hbox{H}$ . In all instances, the measured average LED current variation was lower than 10% of the desired value. A maximum conversion efficiency of 91% is obtained when driving 50 mA through four LEDs (with 14 V input voltage and an inductor of 470 $\mu \hbox{H}$ ). A stable CCM converter operation is also proven by simulation for nine LEDs and 45 V input voltage.

Switching Properties of Liquid Nitrogen Cooled IGBTs and 24 kA Demonstration of Current Multiplier by Inductive Storage

We had been developing a current multiplier by inductive storage (CMIS). The CMIS consists of 24 storage copper coils, which soaked into the liquid nitrogen, demonstrates a 24 kA of output current and the continuous current pulses of 3 pulses per second. Switching performance of the IGBTs and diode were tested in the liquid nitrogen bath. These experimental data were used to design the mega-ampere class CMIS. The system consists of the superconductive magnet section with a temperature of 20 K and the IGBT control switch section with a temperature of 77 K.

Fast discharge in a spherical cavity

The work is devoted to the study of the plasma, created by a fast discharge in a spherical cavity. The discharge was driven by an inductive storage with plasma erosion opening switch (dI/dt ∼1012 A/s). The plasma was produced in a spherical cavity (alumina, 11 mm diameter). Xe, Ar, and He at the pressure 80 Pa were used as working gases. The time evolution of the spatial structure and of extreme ultraviolet (EUV) spectra of the discharge plasma was studied by means of micro channel plate detector. The discharges with Xe and Ar resulted in the stable appearance of the spherically shaped plasma with the diameter about 1–3 mm. The plasma emission in the EUV region lasts ∼500 ns. The EUV spectrum of Ar discharge at the moment of maximum of the electron temperature Te contains the lines of Ar X (ionization potential 478.7 eV), that indicates a value of Te in the range 50–100 eV. The mechanism of plasma appearance can be the cumulation of the convergent spherical shock wave, generated by fast heat deposition and magnetic pressure in working media near the inner surface of the discharge volume.

A continuous conduction mode low-ripple high-efficiency charge-pump boost converter

In this paper, a new continuous conduction mode (CCM) low-ripple high-efficiency charge-pump boost converter is presented. Its components include a double voltage charge pump and a low pass LC filter. The voltage boost ratio of the positive low-ripple output voltage of the proposed converter is (1 + D) where D is the duty cycle of the control switching signal waveform. Since the energy storage inductor is connected to the power source and the load at all times, the proposed converter always operates in CCM, the transient responses are fast, and the current stress on the output capacitor is reduced and the output voltage ripple is small. In this paper, the operation principles of the CCM low-ripple high-efficiency charge-pump boost converter are described in detail. Its circuitry is designed and implemented with a TSMC 0.35 μm CMOS processes whose operation frequency is 1 MHz. The circuitry is simple and the power conversion efficiency is up to 90.95 %, and the transient response is only 7 μs.

Note: Compact, reusable inductive-storage-cum-opening-switch based 1.5 GW single-shot pulsed power generator

The results of a very-compact (Marx generator-cum-inductor confined into 0.20 m cylindrical diameter and 0.75 m length) and light-weight (<15 kg) pulsed-power generator are being presented in the paper. The load voltage at 10.5 Ω is measured 125 kV (150 ns full width at half maximum FWHM) with 1.5 GW peak-power. The use of single-optimized-exploding-copper-wire along with the use of air for all the switches of the generator (closing switches of Marx generator used as primary energy source and opening switch of exploding wire) make device very attractive. Marx generator shape itself provides the desired inductance for the inductive storage.

Output Voltage Control and Efficiency Improvement of Multistage Type Impulse Voltage Generator by Utilizing Inductive Energy Storage

In this paper, we propose two control methods of the static impulse voltage generator to lower the influence of DC voltage source fluctuations on the output voltage and to improve its efficiency by reusing discarded inductive storage energy. Introducing the output voltage control adjusting the charging period of capacitive and inductive energy in accordance with the source voltage, the output voltage fluctuation by the source voltage decreased 61.1%. Applying the reusing method to it, we estimated with the circuit simulation that the amount of energy which could be recovered was 21.0% and the efficiency of energy transfer was improved from 60.4% to 76.7%.

Field of researches and applications domains for compact and large-scale DPF devices: Current assets, problems and essentials

Examination of the most important processes taking place in Dense Plasma Focus (DPF) device that lead to the production of very bright flashes of neutrons and X-rays is presented. It is shown that the current abruption (CA) phenomenon accompanied by the plasma-diode formation plays the key role in these events. Issues of matching of different primary loads with plasma inductive storage and subsequently with plasma diode are discussed. It is shown that at the intermediate energies it is possible to attain the perfect matching. Results in some applications of medium-sized DPF obtained recently in radiation material science, dynamic quality control, biology and medicine are presented. It is shown that for better matching at very high energies the classical intermediate energy compressing element can be used. Besides schemes with laser support switching are discussed. Extrapolations of DPF phenomena to very high and very low energies with their feasibility are examined. Envisioned applications of such huge and tiny DPF devices in power production, medicine and electronics are discussed.

Computer and full-scale models of magnets with a single-layer quasi-force-free winding and evaluations of the possibility of using such magnets in inductive energy stores

Results of numerical modeling and experiments, which confirm the possibility of greatly decreasing the mechanical stresses in the equilibrated magnet winding compared with the usually implemented winding, are presented. An increase in the specific energy capacity of the inductive energy store is pointed out in case of using such winding in it. The possibilities of correction upon the violation of the equilibrium in the actual magnet winding because of the deviation of its configuration from the calculated one are shown.

A High-Power Capacitor Charger Using IGCTs in a Boost Converter Topology

A compact high-power capacitor charger with a boost converter topology is developed using high-power integrated gate-commutated thyristors as switches and a high-energy density coil as inductive buffer storage. This paper describes the design and the corresponding experimental investigations of the charger in combination with a powerful dc current source, a flywheel energy storage system. A 900-μF capacitor could be charged up to ~ 5 kV within 100 ms. The average charging power of the converter is . The results show that the described capacitor charger is a cost-effective and compact alternative to commercially available products.

A Power Electronics Equalizer Application for Partially Shaded Photovoltaic Modules

This paper studies a photovoltaic (PV)-module-embedded power-electronics topology derived from a battery equalizer. The proposed topology eliminates the multiple maximum power point peaks common to partial shading in PV modules. The topology does so by equalizing the overall energy of the PV module through the use of only one inductive storage element. A theoretical study is carried out to describe the physical equations of the topology. Based on it, a prototype is designed and built. It is tested with a partially shaded PV module, raising its power output by nearly 40% at best. The results are compared to similar topologies dedicated to mitigate partial shading in PV applications.