General Equivalent Circuit Research Articles

Equivalent circuit analysis for magnetostatic wave devices

Magnetostatic wave (MSW) devices are potentially very promising for carrying out signal processing directly at microwave frequencies, and recently have been receiving much attention. Although the development of a general design theory is essential for significant progress in the signal processing capabilities of the MSW devices, relatively few design theories have been discussed in the past. This paper extends and improves the general equivalent circuit approach to the magnetostatic wave devices proposed and discussed earlier. Based on the definitions of the purely magnetostatic terminal parameters and the magnetostatic characteristic impedance, the electromagnetostatic energy conversion is discussed and the appropriate general equivalent circuit models for the MSW devices are developed. Calculated insertion losses for various MSW devices are in excellent agreement with experimental results.

Analysis of MSW Transducer Electrode Design by Use of Weighting Functions

We theoretically analyzed MSW transducer electrode design by use of weighting functions. The method is based on the general equivalent circuit model for the MSW devices we developed and extended earlier. The position of each electrode and the geometrical factor are weighted spatially using a function whose Fourier transform is a square pulse in the k domain. This technique is very effective in the design of an MSW filter with a flat frequency response. The method may be extended to various signal processing applications in the future.

Improved Equivalent Circuit Analysis for Magnetostatic Wave Devices

We extended and improved the general equivalent circuit approach to the magnetostatic wave (MSW) devices we proposed and discussed earlier. In the theory we analyzed various possibilities of general equivalent circuit models for the MSW devices (MSSW, MSFVW and MSBVW). Appropriate general equivalent circuit models for all the MSW devices have been developed. The insertion losses of these devices based on the equivalent circuit models were calculated and excellent agreement with experimental results was obtained.

静磁波デバイスの等価回路解析

Magnetostatic wave (MSW) devices are potentially very promising for carrying out signal processing directly at microwave frequencies, and recently have been receiving much attention. Although the development of a general design theory is essential for significant progress in the signal processing capabilities of the MSW devices, relatively few design theories have been discussed in the past. This paper extends and improves the general equivalent circuit approach to the magnetostatic wave devices proposed and discussed earlier. Based on the definitions of the purely magnetostatic terminal parameters and the magnetostatic characteristic impedance, the electromagnetostatic energy conversion is discussed and the appropriate general equivalent circuit models for the MSW devices are developed. Calculated insertion losses for various MSW devices are in excellent agreement with experimental results.

A General Equivalent Circuit Model For Magnetostatic Wave Devices

A general equivalent circuit model for magnetostatic wave (MSW) devices proposed by the author is discussed. The model consists of purely magnetostatic lumped elements rather than the electrical ones discussed so far. In the proposed model, a magnetomotive force f, a magnetostatic current l, and a magnetostatic characteristic impedance z0 are so defined that the power carried by the MSW through the cross-section of the sample is correctly described. The validity of the model is examined for the magnetostatic backward and forward volume waves by calculating z0 and the radiation resistance.

A general equivalent circuit (GEC) of electric machines including cross-coupling saturation and frequency effects

A general equivalent circuit (GEC) is proposed for the orthogonal-axis model of synchronous, induction and commutator machines with crosscoupling saturation and frequency (or skin) effects included simultaneously but considered independently of each other. The cross-coupling saturation is accounted for through the so-called saturation equations based on the experimentally proven assumption that there is a unique and distinct main path magnetizing curve along each of the d and q axes. The frequency effects are simulated through fictitious multicircuits. The complete equations of the synchronous, induction and commutator machines are given, from which the GECs are obtained. It is shown that there is only one GEC for both orthogonal axes, which are cross-coupled due to saturation. >

Electrocapillary sensing devices. VI. Displacement meters

The theory is presented of electrocapillary sensing devices of vibrational motion displacement amplitude resulting from the general equivalent circuit of electrocapillary transducers. Typical frequency characteristics are shown which confirm the theoretical considerations.

Dynamic theory of the alternating current response of semiconductor electrodes under illumination

A photoinduced admittance enhancement has been observed on n-GaAs and n-GaP electrodes in the potential range between flatband and stationary photocurrent onset. In order to provide a theoretical evaluation, the alternating current response of a semiconductor electrode under illumination has been investigated on the basis of non-equilibrium treatment of the carrier balance in the semiconductor and of the interfacial charge transfer kinetics. Superposition of an irreversible stationary and small-amplitude periodic rate has been treated for the following cases of charge transfer at the interface: (a) one-step electrochemical process; (b) two-step electrochemical process including an adsorbed intermediate and partial charge transfers; (c) parallel couple of one-step electrochemical and partial charge transfer chemisorption process. Empirical criteria for preference of charge transfer over surface recombination have been considered. In connection with the present development, the general equivalent circuit of a semiconductor electrode has been briefly derived from the dynamical charge balance. The theoretical approach of the stationary photocurrent-voltage curve has been discussed and refined.

Comparison Of Two Methods For Modeling Large-Signal Alternating Magnetic Fields Using Finite-Elements

As part of EPRI Project RP 1288-1 methods have been developed for applying finite element techniques in developing large generator equivalent circuit models. In earlier work, non-steady-state effects have been handled on a linearized basis, invoking the assumption of small signals. This paper describes more elaborate finite element techniques, which include magnetic non-linearities in non-steady-state calculations. The two methods compared are (a) the direct time-integration of the finite-element vector potential diffusion equation and (b) solution of the diffusion equation with phasor time dependence, assigning variable permeabilities in an iterative manner. Results of the two methods are compared using simple, slab geometry, but at flux density levels where gross non-linearities exist. These results are viewed as providinig cross-verification of the two procedures, and provide the basis for application of these techniques to generator analysis.

Modelling and analysis of d.c.-d.c. converter using y-parameters

This paper describes an impulse-response method to find the low-frequency y-parameters of d.c. to d.c. switching converters in both the continuous and discontinuous modes. Using an example of a forward converter, the applications of the y-parameters are illustrated by the determination of: the general equivalent circuit; the d.c. output voltage; the critical condition between continuous and discontinuous modes of operation; the equivalent circuit under steady state condition; the transfer function between small change in d.c. input voltage and the resultant change in d.c.output voltage; the transfer function between small change in duty cycle and the resultant change in d.c. output voltage. The y-parameter approach can easily be applied to other types of converter circuits. Its simplicity makes it particularly suitable for more complex types of converters

TRANSIENT PERFORMANCE ANALYSIS OF POLYPHASE HYSTERESIS-RELUCTANCE MOTORS

Abstract This paper presents some important aspects of the run-up characteristics of polyphase hysteresis-reluctance motors. Analysis to predict the transient and asynchronous performances of these type of motors are presented. A general equivalent circuit model is developed for the sub-synchronous mode of operation. The experimental rotor was made of 36% cobalt-steel alloys and tested by using a stator of polyphase generalized machine. A discussion to Investigate the influence of motor parameters on run-up response Is given. Digital simulation studies have been carried out for the proposed analysis and the results are compared to those of a practical model

Negative frequency aspects of doubly fed machine analysis

Negative frequencies occur in the analysis of doubly fed machines. The properties of negative-frequency quantities are investigated and volt-amp relationships described, for both single-phase and three-phase circuits. Transformations of negative-frequency quantities to equivalent positive-frequency quantities are considered. A general equivalent circuit of the doubly fed machine is described which is directly applicable over the entire operating range.

Generalized zero-sequence and anti-zero-sequence performance of induction machines

The present paper derives a new general zero-sequence steady state ladder equivalent circuit of threephase induction machines where zero-sequence currents can simultaneously flow in both the stator and rotor windings. A general expression for the zero-sequence torque is also derived. In machines with even number of phases, anti-zero sequence currents can also flow. It is shown that they can produce a finite torque and a new anti-zero-sequence steady state equivalent circuit of induction machines is presented. This is shown to be similar to the space-harmonic equivalent circuit of a single-phase induction machine, where the number of polepairs is equal to one half of the stator phase number.

EQUIVALENT CIRCUIT OF TRANSFER FIELD MACHINE FOR ASYNCHRONOUS MODE OF OPERATION

ABSTRACT For the first time, performance analysis of asynchronous mode operation of the novel transfer field (TF) machine is presented. A general equivalent circuit for polyphase, sinusoidal steady-state.operation is derived. It is shown that this machine displays speed-torque characteristic similar to that of conventional polyphase induction machine. An analysis of performance is made for values of speed across the range from stall to synchronous speed. Laboratory measured data are compared with the calculated values showing excellent correlation.

Time, frequency, and z-domain modified nodal analysis of switched-capacitor networks

A rigorous and general derivation of the modified nodal equations needed for a time, frequency and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</tex> -domain analysis of multiphase switched-capacitor networks is given. Also a general equivalent circuit for switched-capacitor networks is derived. This technique allows to handle continuous coupling, piecewise-constant inputs as well as continuous inputs. These results can be used to adapt existing circuit analysis programs, based on modified nodal analysis, for efficient simulation of switched-capacitor networks.

Precise Equivalent Circuits of Mechanical Filters

A general two-port equivalent circuit of the resonator is derived, valid for medium bandwidths, which passes into the familiar medium bandwidth oneport equivalent when either of the two ports is open-circuited. When the circuit is reduced to the narrow-band equivalent, instead of the expected parallel tuned circuit, a bridged tee circuit is obtained. With this new equivalent circuit it is possible to explain wme hitherto unexplained degradations of the transmission characteristics of fiiters with bypass couplers. It is shown that the pa- rameters of the one-port as well as the two-port equivalent circuits can be determined by measurement of the coupling resonances of groups of four resonators in which all the resonators and couplers are identical.

EQUIVALENT CIRCUITS FOR DOUBLE-CAGE INDUCTION MOTORS

ABSTRACT It is shown that, if the classical general equivalent circuit for double squirrel-cage motors is accepted, there is a double infinity of other circuits which are mathematically equivalent to the same motor. A physical discussion is given of this fact, and a practical example is described.

Transient and steady-state operation of induction motors with general two-side asymmetry

A new, general equivalent circuit is derived by using symmetrical-component theory for two-side asymmetrical three- and two-phase induction machines. The steady-state equivalent curcuit for the general three-phase case consists of controlled generators too, this is due to general asymmetry. All the elements of the equivalent circuit can be directly calculated from the known phase-coordinate stator and rotor components. The equivalent circuit is simplified for a two-side asymmetrical two-phase machine, realization is carried out with d, q components. As an extreme case, approximative the steady-state equivalent circuit is also derived for a single-phase machine with rotor asymmetry. The analogy is pointed out with the well known steady-state equivalent circuit of the single phase motor with symmetrical rotor. For the purpose of the direct measurement of an asymmetrical squirrel-cage induction motors' rotor currents, a model with external rotor is suggested. — For transient operation, a state-variable differential equation is derived by using Park-vector techniques, saturation of the main flux path is also present.

Distributed variable-capacitance microstrip lines for microwave applications

Variable-capacitance microstrip lines are easily prepared on semiconducting substrate by use of IC-technology yielding a form of distributed nonlinear transmission line for high-frequency operation. Its cross section may be adequate to that of any varactor diode. Wave propagation determined by a very slow TM-surface mode is described by a general equivalent circuit thus characterizing the nonlinear properties of such lines. Optimum performance together with attainable configurations and possible applications are discussed.

A nonlinear equivalent circuit for IMPATT diodes

A lumped nonlinear equivalent circuit is developed for Read-type IMPATT diodes, using the carrier transport equations for the device. The validity of this circuit is not restricted to sinusoidal signal waveforms. It can be used for quantitative calculations of device performance as well as for qualitative predictions of the general features of IMPATT diode behavior. The general equivalent circuit is further simplified for the case of sinusoidal excitation and its application is demonstrated by simple examples.