Switched-current analysis program

This book is concerned with circuit simulation using National Instruments Multisim. It focuses on the use and comprehension of the working techniques for electrical and electronic circuit simulation. The first chapters are devoted to basic circuit analysis. It starts by describing in detail how to perform a DC analysis using only resistors and independent and controlled sources. Then, it introduces capacitors and inductors to make a transient analysis. In the case of transient analysis, it is possible to have an initial condition either in the capacitor voltage or in the inductor current, or both. Fourier analysis is discussed in the context of transient analysis. Next, we make a treatment of AC analysis to simulate the frequency response of a circuit. Then, we introduce diodes, transistors, and circuits composed by them and perform DC, transient, and AC analyses. The book ends with simulation of digital circuits. A practical approach is followed through the chapters, using step-by-step examples to introduce new Multisim circuit elements, tools, analyses, and virtual instruments for measurement. The examples are clearly commented and illustrated. The different tools available on Multisim are used when appropriate so readers learn which analyses are available to them. This is part of the learning outcomes that should result after each set of end-of-chapter exercises is worked out. Table of Contents: Introduction to Circuit Simulation / Resistive Circuits / Time Domain Analysis -- Transient Analysis / Frequency Domain Analysis -- AC Analysis / Semiconductor Devices / Digital Circuits

The main objective of the paper is to design of Fractional order PID (FOPID) controller for heat flow system using evolutionary algorithms. The recent developed metaheuristic algorithms such as Ant Lion Optimizer (ALO), Grey Wolf Optimizer (GWO) and Moth Flame Optimizer (MFO) are used in the FOPID design. The FOPID design for heat flow system is formulated as an optimization problem to minimize different indices error such as Integral Absolute Error (IAE), Integral Squared Error (ISE), Integral Time Absolute Error (ITAE), Integral Time Squared Error (ITSE). The evolutionary algorithm based FOPID control performances are compared with PID control performance for the heat flow system. In addition, the proposed methods have superiority value in terms of transient and frequency domain analysis than the traditional and PID methods. Comparative performance evaluation of meta-heuristic based FOPID design for heat flow system has not carried out before.

Switched-current (SI) circuits represent a current-mode analog sampled-data signal processing technique realizable in standard digital CMOS technologies. Unlike switched-capacitor (SC) circuits, SI circuits require only a standard digital CMOS process. SI circuits use MOS transistors as the storage elements to provide analog memory capability. Similar to the operation of dynamic logic circuits, a voltage is sampled onto the gate of a MOSFET and held on its noncritical gate capacitance. The held voltage signal on the gate causes a corresponding held current signal in the drain, usually proportional to the square of the gate-to-source voltage. Design issues related to the implementation and performance of SI circuits are presented. SI filters show comparable performance to SC filters except in terms of passband accuracy. The major source of error is nonunity current gain in the SI integrator due to device mismatch and clock-feedthrough effects. For the initial CMOS prototypes, the current track and hold (T/H) gain error was about 2.5%. >

The calculation of transient electromagnetic fields in solid conductors becomes more important in the future because of the increasing demands on system design under EMC-constraints. The switching of currents in a system of conductors is especially crucial because a transient wave is stimulated in the non-conducting environment. The energy balance for the switching of an exciting current shows that the integration of the dissipated power over the infinite time interval is equal to the energy stored in the magnetic field in the conducting space before switching plus the energy that flows through the conductor's surface during the transient process. The energy difference between the initial field before and immediately after the switching is radiated into the free space by a transient wave that is excited at the moment of switching. This relation is proved for the switching of a continuous current in an elementary coaxial line and the shielding of the transient field of a magnetic dipole of arbitrary orientation by a conducting and permeable hollow sphere.

This paper presents a state-of-the-art review of the recent advances in computer methods for analysis and design of switched circuits in both time and frequency domains. It also presents new research results on time-domain analysis and sensitivity of switched nonlinear circuits, time- and frequency-domain statistical analysis of switched linear and nonlinear circuits, and efficient modeling and analysis of clock feedthrough and charge injection in switched linear circuits. In time-domain analysis, the modeling of switches and its effect on the simulation of switched circuits are investigated. Formulation methods for these circuits are examined. Inconsistent initial conditions arising from ideal switching are investigated and numerical methods that derive the consistent initial conditions are examined. Sampled-data simulation (SDSIM) of switched linear circuits including clocked sigma-delta modulators is investigated. SDSIM is extended to switched nonlinear circuits. Time-domain sensitivity of switched linear and nonlinear circuits is analyzed using SDSIM. Efficient time-domain statistical analysis of switched linear and nonlinear circuits is introduced, and their effectiveness is assessed using Monte Carlo simulation. Methods that compute the effect of the clock jitter of periodically switched linear (PSL) circuits are examined. Time-domain noise analysis of PSL circuits is investigated. In frequency-domain analysis, exact frequency analysis of multiphase PSL circuits is reviewed. Sensitivity analysis of these circuits is examined in detail. Adjoint network theory and its usefulness in noise and sensitivity analysis of switched linear circuits are studied. Group delay of PSL circuits is investigated briefly. Efficient modeling and analysis of clock feed-though and charge injection of PSL circuits are introduced. Distortion and sensitivity of periodically switched nonlinear circuits with mild nonlinearities are investigated. Finally, frequency-domain noise analysis of PSL circuits is examined.

For applications requiring low-voltage low-power and real-time processing, a novel scheme for the VLSI implementation of wavelet transform (WT) using switched-current (SI) circuits is presented. SI circuits are well suited for these applications since the dilation constant across different scales of the transform can be implemented, and controlled by both the aspect-ratio of the transistors and the clock frequency. The quality of such implementation depends on the accuracy of the corresponding wavelet approximation. First, an optimized procedure based on differential evolution algorithm (DE) is applied to approximate the transfer function of a linear steady-state system whose impulse response is the required wavelet. The proposed approach significantly improves the accuracy of approximation wavelets. Next, the approximation of time-domain wavelet function is implemented by the SI analog filters. Finally, the design of the complete SI filter based on first-order and biquad section as main building block is detailed. Simulations demonstrate the performance of the proposed approach to analog WT implementation.

Transient stability domain estimation of AC/DC systems considering HVDC switching characteristics based on the polynomial Lyapunov function method

In this paper, digital CMOS switched-current (SI) circuits with low charge-injection errors are presented. These circuits are based on the operation of the switches at virtual-ground nodes to result in signal-independent charge injection. Based on this scheme, different topologies for the memory cell are discussed. To verify the theoretical concepts developed, a third-order elliptic low-pass SI filter is implemented in a 0.25-/spl mu/m digital CMOS process. The filter nominally operates with a clock frequency of 10 MHz, cutoff frequency of 1 MHz, and a power supply of 2.3 V, while consuming 29 mW of power and processing input signals as large as 600-/spl mu/A peak differential. The low-charge injection nature of the circuit is reflected in its low total harmonic distortion of -59 dB for a 0.3-MHz signal with a modulation index of 0.5.

The paper provides a new approach to an efficient reduction of switching noise in switched-current (SI) circuits. This approach makes use of a noise-free current-mode switch that can cut itself off to shield a circuit node, at which the voltage needs to be preserved precisely, from switching noise. With this approach, a reduction rate of more than 90% can be achieved. This approach can be very easily implemented. It does not require any special fabrication process, area-consuming components, matching devices, or complex clocks. This work can lead to a significant improvement of the operation quality of SI circuits without sacrificing speed and power dissipation.

This paper presents a architecture to reduce charge injection in single-ended switched capacitor networks where high precision is inevitable. The key advantage of this architecture in switched capacitor network is that without any additional circuitry, the switch non-idealities like charge injection and clock feedthrough can be improved significantly. The design is done in 0.18µm TSMC process. The results shows that the proposed switching scheme is 50% more accurate compared to all other conventional techniques in handling charge injection modeling inaccuracies in CMOS switches.

Based on possible defects on the layout of a practical non-ideal switch, fault model and test generation of current copiers, basic building block of switched-current circuits, are presented in this study. We consider two types of switches, current switches and voltage switches, which have been commonly used in both switched-current circuits and switched-capacitor circuits, and both catastrophic and non-catastrophic faults of transistors used as switches. The generated test sequence achieve full testability of current copiers. The tester and test process are readily applied for any switched-current circuits.

The present study is focused on accurate prediction of the Morton effect problem including journal asymmetric heating and the corresponding long period amplitude oscillations using a nonlinear time transient rotor-dynamic simulation. This paper presents a theoretical model of thermal induced synchronous instability problems in a nonlinear rotor–bearing system, and suggests a new computational algorithm for the nonlinear transient analysis of the Morton effect where the dynamic and thermal problems are combined. For the analysis of the Morton effect problem, a variable viscosity Reynolds equation and a 3D energy equation are coupled via temperature and viscosity, and solved simultaneously. Three-dimensional heat transfer equations of bearing and shaft are modeled by a finite element method, and thermally coupled with the fluid film via a heat flux boundary condition. Asymmetric heat flux into the synchronously whirling rotor is solved by the orbit time averaged heat flux from fluid film to the spinning shaft surface. The journal orbit is calculated by the nonlinear transient dynamic analysis of a rotor–bearing system with a variable time step numerical integration scheme. For the computation time reduction, modal coordinate transformation is adopted in dynamic and thermal transient analysis. Thermal bow effect makes a significant change to the dynamic behavior of a rotor–bearing system, and a thermal hysteresis bode plot, that is one of the characteristics of the Morton effect problem, is presented with time varying spin speed.

The output stability of the displacement sensors is essential to enhance the reliability of active magnetic bearings in the high-temperature applications. This paper proposes a novel temperature drift compensation method for exponential hysteresis characteristics of high-temperature eddy current displacement sensors. The transient thermal analysis for the sensing assemblies demonstrate that the temperature drift errors are mainly induced by the temperature variation hysteresis effect: one is the dynamic lag between the probe coil and the air gap, and the other is the dynamic lag between the target material and the air gap. An auxiliary device consisting of compensation probe and compensation plate is designed to solve the hysteresis effect. The thickness of the compensation plate is determined by simulating the transient thermal analysis of the compensation plate and the measured target region. The model analyses also find that the exponential temperature drift at different determined displacement states is similar under the same temperature gradient. With this error characteristic, the differential circuit is used to eliminate the exponential hysteresis temperature drift. Experimental investigations show the effectiveness of the proposed solution.

Improving the efficiency of the electricity usage is an important concern these days relaying on monitoring techniques mainly divided into two categories: the intrusive monitoring that is focused on measure the power consumption of each electrical load individually and the non-intrusive monitoring which measure the power consumption from a centralized point and determine which electrical loads are presented. Electrical signatures are the main components of a non-intrusive monitoring system; these signatures are presented on the transient and steady state events on the signal. In order to classify these events according to its signatures, it is necessary to detect when and where these events occur. This work presents a method to detect and classify steady state events using the fuzzy c-means clustering algorithm; the proposed method is based on a frequency domain analysis, more specifically the analysis of the fundamental frequency and the first odd harmonic in order to improve the computational cost of the event classification algorithm.

The bearing faults may lead to expensive and catastrophic failures, which affect the reliability of power drivetrain in electromechanical system. To reduce impact of the bearing failures, accurate analysis and timely diagnosis are required for improved reliability of the electromechanical systems. In this work, an enhanced transient current signature analysis has been investigated for aircraft application using permanent magnet synchronous motor with bearing defects. The motor current under steady-state and transient conditions is acquired from an experimental test-rig with bearing defects at different loading and speed levels. The acquired signals are first investigated using frequency domain analysis and then compared with the time–frequency domain analysis such as wavelet analysis. The discrete wavelet transform is used to analyze on the calculated residual current for the bearing fault diagnosis. The proposed time–frequency-based technique is able to provide useful features that characterize the condition of the bearings on transient current. Further, back-propagation neural network is used over the calculated features which distinguishes the defective bearing from the healthy bearing with high accuracy.