Pulsed Inductor Research Articles

Research on electromagnetic shielding device for pulse inductor in CRAFT quench protection system

The quench protection system is the most important safety equipment of the Comprehensive Research Facility for Fusion Technology (CRAFT) project, which is used to protect asset security in the event of superconducting device quenching. Since the pulse inductor of the quench protection system works under extreme conditions, a strong induced magnetic field will be generated around the equipment, which will affect the normal operation of other electrical equipment in the inductor cabinet. Aiming at this situation, it is necessary to analyze the changing magnetic field of the inductor. This paper proposed a new shielding structure that can effectively reduce the magnetic induction around the inductor, and the effectiveness of the design was verified through simulation.

Research on Loss and Temperature Rise of Pulse Inductor for Electromagnetic Rail Launch

The copper foil pulse inductor used for electromagnetic rail launch works in instantaneous super-high current conditions, and the copper foil needs to bear high current density, which also affects the eddy current distribution in the metal shell. The loss and temperature rise generated in the copper foil and the shell affect the efficiency and operation stability of the pulse inductor, and are important performance indicators to test whether the pulse inductor can achieve rapid and continuous pulse discharge. The magneto-thermal coupling simulation model was built by the finite element method (FEM) and boundary element method (BEM), and the numerical calculation results of the loss and temperature rise of the copper foil and shell of the pulse inductor were obtained when the electromagnetic rail launched. Aiming at the problem of large shell loss, a structural optimization scheme is proposed to increase the gap between the copper foil and the shell and reduce the wall thickness of the shell. The simulation shows that after the structure is optimized, the copper foil loss slightly increases by 1.29% during a single launch, but the shell loss decreases by 21.33%, at the same time, the temperature rise of copper foil and the strength of the shell meet the safety requirements of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6\times $ </tex-math></inline-formula> consecutive launches. Finally, the accuracy of the simulation calculation model and the scheme to reduce eddy current loss of shell are verified by experimental measurement.

Thermal Analysis of the Pulse Inductor for Electromagnetic Launch Under Continuous Discharge Condition

The solenoid pulse inductor is a key component of the electromagnetic launch (EML) system, and effective thermal management is a necessary condition for reliable and stable operation under continuous discharge condition. A 3D transient coupling heat transfer model for the solenoid pulse inductor with liquid cooling mode was established, and the temperature distribution and the characteristics of heat dissipation of the inductor under continuous discharge condition has been analyzed. A temperature measurement system was designed, and the accuracy of the 3D coupling model has been verified. In addition, effects of the flow rate, the inlet temperature and the coolant on the efficiency of liquid cooling were analyzed by using this model. The results show that during continuous discharge, the maximum temperature and maximum temperature difference of the inductor continue to increase, but the rising speed rapidly slows down. Raising the flow rate can effectively improve the efficiency of the liquid cooling and decrease the temperature difference in the inductor during continuous discharge, but the marginal benefit of raising the flow rate is gradually reduced. Dropping the inlet temperature has little effect on the efficiency of the liquid cooling, and ethylene glycol solution can replace deionized water as the liquid cooling coolant for the pulse inductor under low temperature condition. This paper is expected to help to improve the thermal management and optimize the performance of the solenoid pulse inductor.

Simulation analysis of thermal management of inductor applied to pfn under continuous discharge condition

The pulse forming network (PFN) is an important component of the electromagnetic launch system, and its continuous discharge performance at same frequency is of great significance for the development of electromagnetic launch system. Pulse inductor is one of the key components of PFN, which has a decisive influence on the amplitude, pulse width and wave front time of discharge current. In order to study the thermal management scheme that could meet the temperature control requirements of pulse inductors under continuous discharge condition, an electromagnetic-thermal-fluid coupling model is established, and the temperature change of pulse inductor under the condition of liquid cooling and natural cooling is analyzed. It is concluded that the natural cooling scheme cannot meet the temperature control requirements, while the liquid cooling scheme can meet it. But the disadvantage of the liquid cooling scheme is that the maximum temperature difference inside the inductor will be increased.

Preliminary Design of Pulse Inductor Applied for 100-kA Quench Protection System

The quench protection system in a large-scale superconductor test facility (LSTF) aims to protect the superconducting magnets from being damaged by long time and severe conducting current. A super-high pulse current from oscillation between a pulse inductor and a storage capacitor flows reversely into the main circuit to force the current in the main circuit cross zero, which ensures the reliable turn-off of the mechanical switch to protect the superconducting magnets. Furthermore, the pulse inductor also plays an essential role in adjusting the pulsewidth and the limiting pulse peak value. For the inductor, the pulse current is up to 130 kA and the rated inductance is 30 μH. To release the electromagnetic (EM) force largely and reinforce the structure and insulation properties, a circular multi-winding structure with epoxy resin-casting technique is presented. Based on the 2-D/3-D model built in finite element analysis software, the structure resist, deformation, heat, and EM environment of the design are simulated. The terminals are also optimized to minimize the damage from the EM force and extend the operation life of the inductor. In addition, a fatigue analysis is carried out to estimate the working life of the inductor and verify the reliability of the structure under the 130-kA pulse current working condition.

Efficient SSHI circuit for piezoelectric energy harvester uses one shot pulse boost converter

In this paper, a one shot pulse inductor boost converter is presented which provides 4 V output at 60 ms of delay using 0.15 V vibration source. Energy harvesting plays an important role in biomedical implants sensors where the extended life time is the most prominent factor. Synchronized switch harvesters on inductor (SSHI) comes into existence due to its highly efficient interface with energy harvesters. The main aim of this paper is to obtain high efficiency and maximum power extraction from piezoelectric energy harvester using SSHI and one shot pulse boost converter. This circuit does not require any external voltage and provides the controlled output with reduced power dissipation of approximately 10 nW and power consumption achieves between 1 and 10 mW. The start-up problem due to variable vibrational energy source is avoided by using one shot pulse inductor boost converter. This converter uses only one shot period for maximum charge transfer during first switching cycle. In 180 nm CMOS process, result shows that pulse boost converter can be directly powered from low voltage of 0.15 V with efficiency of ≈ 90% across the load of 6 µA current having switching frequency of 206 kHz. It also eliminates the problem of switching losses and reduces leakage current by saving board space and external components cost.

Magneto-Permeabilization of Viable Cell Membrane Using High Pulsed Magnetic Field

In this paper, we present novel experimental data of the magnetic permeabilization of the mammalian cells in high pulsed magnetic fields up to 16.4 T. Two designs of the multilayer solenoid-type pulsed inductors, which were adapted for the biological experiments, are presented. The induced electric field is analyzed using the finite-element method analysis. The experimental methodology and the pulsed magnetic field setups are overviewed. The experimental results with mouse myeloma cell line Sp2/0 in pulsed magnetic field after pulse bursts and single-pulse treatment are presented. The SYTOX Green dye was used for the estimation of the permeabilization process efficacy. It has been shown that the 16.4 T submillisecond low ( $ T/s) dB/dt magnetic field pulses do not cause any observable dye uptake changes using the proposed methodology. The short repetitive microsecond range pulses ( $dB/dt>0.8 \,\times \, 10^{6}$ T/s) result in an average up to 2.6% ± 0.5% increase of the dye uptake.

Litz Wire Pulsed Power Air Core Coupled Inductor

A methodology for designing high-current air core pulsed power coupled inductors is presented with emphasis on simplicity. Standard inductor design is based on derated current densities and magnetic flux densities to make the most efficient utilization of materials, but the presented pulsed power inductors have low duty cycle and are designed based on impedance and physical size. The frequency content of applied pulses manifests as strong eddy currents that cause high ac resistance. The use of litz wire is justified for extremely low-resistance inductors and, in our case, resulted in a design that is smaller, lighter, and less costly than when using conventional conductors. Wheeler's formula is used to estimate the optimal geometry, and finite-element analysis is used to verify and finalize the design. Several 2.2- $\mu\mbox{H}$ inductors were successfully designed and built to within 10% tolerance.

Thermal Performance Study on Pulsed Inductor

Based on the features of large heating power per unit volume and small cooling surface area, the thermal management is one of the key technologies and plays a significant role for the pulsed inductor. A mathematical model that describes the heat transfer and thermal accumulation processes with the operating condition of periodic pulse loading for the pulsed inductor has been developed and validated in this paper, and the model results show a fine accuracy as compared with the test data. In addition, a computer code has been implemented to simulate the thermal accumulation and performance of natural cooling with different operating conditions (as the various of pulse voltage, pulse spacing, and pulse duration). The results show that the pulse voltage, pulse spacing, and pulse duration are the focus factors to the thermal accumulation for the pulsed inductor, and the effect of the natural cooling by surface area of the inductor is poor under the periodic pulse loading.

Joule heating influence on the vitality of fungi in pulsed magnetic fields during magnetic permeabilization

Generation of the pulsed magnetic fields that are 5–6 orders of magnitude higher than the geomagnetic field requires switching of high pulsed currents. As a result, the occurrence of the Joule heating in the inductors limits the possible biological applications of the pulsed magnetic fields. This work is focused on the investigation of the generated Joule heating inside the inductors of different shapes. The analysis of the Joule heating influence on the vitality of biological objects during magnetic permeabilization is presented. The biological objects that are used in the study are the pathogenic fungi Candida albicans and Trichophyton rubrum, which are the common cases for human infections. The finite element method analysis of the pulsed inductors and the experimental results with the selected pathogenic fungi are overviewed. The limitations of the magnetic permeabilization technique due to the generated Joule heating are identified.

ЕЛЕКТРОМАГНІТНІ ПРОЦЕСИ В ІМПУЛЬСНИХ ІНДУКТОРАХ ПРИСКОРЮВАЧІВ ЕЛЕКТРОНІВ

Числовими методами досліджено процес установлення магнітного поля в разі його збудження в перерізі замкненого шихтованого осердя імпульсного індуктора. Аналіз поширення поля від меж перерізу виконано за допомогою двовимірної скінченно-елементної моделі хвильового рівняння, записаного в критеріальній формі з використанням еквівалентних значень магнітної μ та діелектричної проникності ε. Розглянуто дві ситуації: 1) середовище шихтованого пакета є анізотропним ідеальним магнітодіелектриком, тобто не має електро-провідності; 2) середовище пакета має ізотропні електромагнітні параметри μ і ε, але має втрати енергії на вихрові струми через наявність електропровідності в шарах феромагнетика. Установлено характер хвильових явищ та умови їх істотного впливу на розподіл поля. Показано, що критерієм переходу до чисто дифузійної картини поширення поля за магнітних чисел Рейнольдса є відношення . Оцінено ефективність використання перерізу осердя за умов, коли роль хвильових явищ є відносно малою із застосуванням швидкості дифузії поля замість швидкості поширення електромагнітних хвиль

Analysis for Temperature Field and Thermal Stress of the Pulsed Inductor

The pulsed inductor is a key device in the pulse power supply (PPS) in electromagnetic launch and electromagnetic propulsion systems. With the requirements of the weaponization of PPS, whether the continuous pulse discharge can be realized is an important criterion for testing the performances of the PPS. During the continuous pulse discharge, the temperature distribution and the thermal stress are created in the pulsed inductor when the electric current flows, and these greatly affect the efficiency and the mechanical structure of the pulsed inductor. The objective of this paper is to investigate the effects of the temperature distribution and the thermal stress on pulsed inductors. First, by using the finite-element method, the theoretical calculation for the temperature distribution is provided. Next, the experiment for studying the temperature distribution of the pulsed inductor is designed; a thermocouple is used to measure the temperature generated during the pulse discharge to show the reasonability of simulation results. Based on the aforementioned results, the theoretical calculation for the thermal stress is given. This paper will help to improve the mechanical structure design and the performance of the pulsed inductor.

Simulation of Electromagnetic Force Between Pulsed Inductor and Internal Structure of Power Supply Module

With the development of electromagnetic launch (EML) technology, the pulsed power supply (PPS) module applied in EML needs to be smaller, lighter, and more compact. Electromagnetic force (EMF) is one of the most serious problems when PPS module works with high current. In this paper, we study the PPS module used in EML technology. The pulsed inductor model is built based on structure characteristics. The distribution of current density in the inductor during discharge is analyzed. The finite element analysis software is used to simulate and analyze the characteristics of the induction current and the EMF. The simulation model is composed of inductor and metals structures. The EMF laws are put forward by simulation of different shaped metals at different positions. By analyzing the distribution of the eddy current and EMF on the metal conductors at different positions, the EMF laws between the inductor and metal conductors in PPS module are presented in this paper.

The Influence of Pulsed Magnet Heating on Maximal Value of Generated Magnetic Field

The influence of pulsed magnet heating on the maximal value of the generated magnetic field is described. The operation of pulsed generator consisting of a capacitor bank, thyristor switch and wire wound pulsed inductor was analysed. The maximum value of the generated magnetic field and pulse duration of pulsed magnet was limited by Joule heating and mechanical stresses. Using Matlab£ Simulink£ software, a flexible model for simulation of thermodynamic processes in pulsed magnet was developed. The calculated results of the maximal value and distribution of magnetic field were verified experimentally and acceptable compliance was achieved using calibrated array of four pick up inductive coils for measurements of axial magnetic field and a current shunt for pulsed current measurements.