J. Chatzakis

Designing a new generalized battery management system

Battery management systems (BMSs) are used in many battery-operated industrial and commercial systems to make the battery operation more efficient and the estimation of battery state nondestructive. The existing BMS techniques are examined in this paper and a new design methodology for a generalized reliable BMS is proposed. The main advantage of the proposed BMS compared to the existing systems is that it provides a fault-tolerant capability and battery protection. The proposed BMS consists of a number of smart battery modules (SBMs) each of which provides battery equalization, monitoring, and battery protection to a string of battery cells. An evaluation SBM was developed and tested in the laboratory and experimental results verify the theoretical expectations.

A system for inverter protection and real-time monitoring

A real-time system for protecting and monitoring a DC/AC converter has been designed and constructed. The proposed system consists of (a) a hardware protection unit for fast reaction, load protection and inverter fail-safe operation and (b) a microcontroller unit for calculating critical parameters of the inverter operation. The control unit malfunctions have not been investigated in this study. The proposed hardware architecture and sensors form a low-cost and reliable control unit. The experimental results show that the proposed system ensures the inverter protection and fail-safe features. The proposed unit can be used to increase the reliability of any power inverter in AC motor drives, renewable energy systems, etc. or can be incorporated in any UPS system.

High repetition rate pseudospark trigger generator

We report the design and development of a high repetition rate pseudospark trigger generator for operating pseudospark switches with a low impedance of approximately 50 Omega between the trigger pins. The trigger generator can be operated from a single-shot mode up to a repetition rate of 1 kHz. It produces 3 kV, 1 mus pulses into a 100 Omega load to trigger a single pseudospark gap. Also, with the addition of a self-break spark gap and pulse forming network, the trigger generator can be used to trigger a pseudospark gap with low jitter. In this configuration, it produces 300 ns, 3 kV pulses with rise time of 10 ns. The jitter between trigger pulses applied to the pseudospark is less than 1 ns.

A PORTABLE PULSED NEUTRON GENERATOR

The design and construction of a pulsed plasma focus device to be used as a portable neutron source for material analysis such as explosive detection using gamma spectroscopy is presented. The device is capable of operating at a repetitive rate of a few Hz. When deuterium gas is used, up to 105 neutrons per shot are expected to be produced with a temporal pulse width of a few tens of nanoseconds. The pulsed operation of the device and its portable size are its main advantage in comparison with the existing continuous neutron sources. Parts of the device include the electrical charging unit, the capacitor bank, the spark switch (spark gap), the trigger unit and the vacuum–fuel chamber / anode–cathode. Numerical simulations are used for the simulation of the electrical characteristics of the device including the scaling of the capacitor bank energies with total current, the pinch current, and the scaling of neutron yields with energies and currents. The MCNPX code is used to simulate the moderation of the produced neutrons in a simplified geometry and subsequently, the interaction of thermal neutrons with a test target and the corresponding prompt γ-ray generation.

Filamentary Structure of Current Sheath in Miniature Plasma Focus

Current sheath dynamics is an important parameter for good focusing or pinching in a dense plasma focus device. In this paper, we present pinching evidence and details of the filamentary structure of the current sheath in a miniature plasma focus device using a time-resolved laser shadowgraphic technique and time-integrated optical imaging.

Real time visualization of dynamic magnetic fields with a nanomagnetic ferrolens

Abstract Due to advancements in nanomagnetism and latest nanomagnetic materials and devices, a new potential field has been opened up for research and applications which was not possible before. We herein propose a new research field and application for nanomagnetism for the visualization of dynamic magnetic fields in real-time. In short, Nano Magnetic Vision. A new methodology, technique and apparatus were invented and prototyped in order to demonstrate and test this new application. As an application example the visualization of the dynamic magnetic field on a transmitting antenna was chosen. Never seen before high-resolution, photos and real-time color video revealing the actual dynamic magnetic field inside a transmitting radio antenna rod has been captured for the first time. The antenna rod is fed with six hundred volts, orthogonal pulses. This unipolar signal is in the very low frequency (i.e. VLF) range. The signal combined with an extremely short electrical length of the rod, ensures the generation of a relatively strong fluctuating magnetic field, analogue to the signal transmitted, along and inside the antenna. This field is induced into a ferrolens and becomes visible in real-time within the normal human eyes frequency spectrum. The name we have given to the new observation apparatus is, SPIONs Superparamagnetic Ferrolens Microscope (SSFM), a powerful passive scientific observation tool with many other potential applications in the near future.

Note: A novel trigger generator for a pseudospark switch

A novel trigger generator for operating a pseudospark switch has been developed based on a series connection of several insulated gate bipolar transistors. The trigger generator can be operated in single shot mode up to a repetition rate of 1 kHz. It is characterized by a fast rise time and low jitter between the output trigger pulses of less than 1 ns. It produces 3 kV, 1 μs pulses into a 50 Ω load that can trigger a pseudospark switch. By eliminating bulkier, slower high voltage components, the overall volume of the trigger generator is reduced. This allows for faster, high voltage switching to take place and thereby increasing the power density of the unit. Using this pseudospark trigger generator, it is possible to trigger single or multiple pseudospark gaps without the requirement to use a pulse shaping circuit.