Development of an Abstract Model for a Non-volatile Static Random Access Memory

The capability to protect against power fluctuations, which eventually prevents the corruption of the memory contents makes non-volatile static random access memory a very good choice for use in highly reliability applications. These random access memories are protected against data writing in addition to preserving the desired contents. Energy source and control circuitries are embedded into it for achieving the same. The control circuitry constantly monitors supply voltage level, inhibits data corruption, and switches on the energy source once it falls beyond a threshold level. In this paper, development of an abstract model for such a non-volatile static random access memory chip has been presented. Test sequences based on this model have been generated for this memory chip. These test sequences have been implemented in VLSI tester and exercised on the chips

Using gradient boosting regression to improve ambient solar wind model predictions

Studying the ambient solar wind, a continuous pressure‐driven plasma flow emanating from our Sun, is an important component of space weather research. The ambient solar wind flows in interplanetary space determine how solar storms evolve through the heliosphere before reaching Earth, and especially during solar minimum are themselves a driver of activity in the Earth’s magnetic field. Accurately forecasting the ambient solar wind flow is therefore imperative to space weather awareness. Here we present a machine learning approach in which solutions from magnetic models of the solar corona are used to output the solar wind conditions near the Earth. The results are compared to observations and existing models in a comprehensive validation analysis, and the new model outperforms existing models in almost all measures. In addition, this approach offers a new perspective to discuss the role of different input data to ambient solar wind modeling, and what this tells us about the underlying physical processes. The final model discussed here represents an extremely fast, well‐validated and open‐source approach to the forecasting of ambient solar wind at Earth

Design and implementation of FPGA-based phase modulation control for series resonant inverters

Owing to the tremendous advances in the digital technology, and improved reliability and performance of the digital control mechanisms, this paper focuses on design and implementation of digital controller using FPGA-based circuit design approach. The digital controller proposed is designed for series resonant inverter used in DC-DC converter applications. Phase modulation technique is proposed for the realization of digital controller on FPGA. The Series Resonant Converter (SRC) is considered in this paper as a preferred converter topology for high power, high voltage power supplies. This paper studies the implementation of phase shift modulation technique using FPGA. The inverter designed, is IGBT based, and Zero Voltage Switching (ZVS) technique is implemented due to reduced stresses on devices and increased efficiency. The phase modulated series resonant inverters (PM-SRC) promotes ZVS operation when its switching frequency is greater than resonant frequency. The designed PM controller is realized using FPGA on which control algorithm and other features of a controller are developed. The series resonant inverter is built and tested for full load under open loop and closed loop conditions at a switching frequency of 20 kHz. The results are presented under varying load conditions. The simulation and the experimental results were found to match closely

Design of low power 4-tap 8-bit adiabatic FIR filter

Abstract — Digital signal processing (DSP) is used to perform filtering, decimation and down conversion in common communications systems, like in oversampling analog to digital converters in wireless and audio applications. This paper describes a design of low order FIR (finite impulse response) filters to be used at the high sampling rates for achieving a low power DSP implementation. This paper reviews the asymptotic zero energy dissipation techniques named as Adiabatic switching logic. The Adiabatic switching technique beats the dynamic power as well as short circuit power, using recycling of energy stored on circuit capacitances instead of dissipating it as heat. PAL technique is the simplest fully adiabatic technique requiring lesser number of power clocks as well as area. Design of four tap 8-bit fully pipelined FIR filter, using PAL adiabatic technique and CMOS technique is compared at different operating frequencies from 5 MHz to 100 MHz, the range which includes input sampling rate for GSM (10 MS/s) and DECT (50 MS/s) standards. Comparison also includes the power loss in adiabatic power supply. Using 0.25 µm technology and 3.3 V voltage supply, energy saving in PAL compared to CMOS is 3 times to 15 times, with frequency varied from 100MHz down to 5MHz. I

Theory of hopping transport of holes in amorphous SiO₂

A quantum-mechanical theory of hole transport in SiO<SUB>2</SUB> is developed based on modeling of the oxide as an array of time-dependent &#948; -function potential well distribution. Holes undergo a variable range hopping transport which is dispersive in nature. The oxide, being an insulator, involves a maximum cutoff phonon frequency of 10<SUP>14</SUP>-10<SUP>15</SUP> s<SUP>-1</SUP>. The Schrodinger equation is solved along with the Poisson equation using a piecewise linear internal field. The theory is applied to metal-oxide-semiconductor structures subjected to a short radiation pulse

Improvement of Transient Response in Microgrids Using Virtual Inertia

Generation is shifting from a centralized power generating facility having large synchronous generators to distributed generation involving sources of smaller capacity. Most of these sources require inverters on the front end while being connected to the grid. Lower available kinetic energy, coupled with less short-circuit current ratio compared to large synchronous generators, compromises the transient stability of the microgrid when isolated from the main grid. Sources in the microgrid use droop control to share power according to their capacity without any form of communication. This paper proposes a novel controller for inverters to improve the frequency response of microgrid under disturbances involving large frequency deviations. It also discusses design of various parameters defined for the proposed control. The microgrid, which has two inverters and two synchronous generators, is simulated using Simulink/MATLAB software to test the proposed control strategy

Inertia Design Methods for Islanded Microgrids Having Static and Rotating Energy Sources

Dynamic frequency regulation and effect of penetration of static and inertial sources on system stability are important issues for islanded microgrid power quality and reliability. This paper presents a novel strategy of utilizing an inverter-based source as a voltage source inverter or virtual synchronous generator (VSG). Electromechanical and power modes are critical for small signal stability of an isolated microgrid having static and inertial sources. Interaction of these modes is analyzed through eigenvalue analysis of microgrid model and differential equations describing respective modes. Inertia is important for providing fault current, determining steady state and transient stability, and better system frequency profile. A novel technique is proposed to include inertia virtually to the inverter-based sources by adding swing equation. Furthermore, inverter-based sources with traditional and modified droop controls and VSGs are compared with respect to inertia, energy, and stability. The proposed control and stability comparison are verified through experimental microgrid setup having three inverter-based sources, which can be alternately operated as VSGs