摘要:

A new technique is used for the accurate analysis of linearly graded and Gaussian-gradedp-njunctions, which permits calculation of the depletion-region width under high forward-bias conditions. Such an analysis is very useful for applications in which one wishes to analyse a complete junction-device structure (such as a bipolar transistor). The results obtained represent a considerable improvement in space-charge modelling over previous approaches to approximate linear analysis. The computer algorithm is discussed as a solution process for implementing the scheme.

DOI:10.1049/piee.1979.0089

出版商:IEE    

年代:1979

数据来源: IET

摘要:

An upper bound can be calculated for the decoder error probability of convolutional coded data with Viterbi decoding by summing the numbers of error paths weighted by the path preference probabilities. This method can be readily applied for uncorrelated errors, but, for correlated noise, particularly with soft decision, the calculation of the path preference probabilities is more difficult. The method of importance sampling has been applied to this calculation using the noise-covariance matrix as input. Some results obtained by applying this technique are presented and compared with simulated decoding.

DOI:10.1049/piee.1979.0090

出版商:IEE    

年代:1979

数据来源: IET

摘要:

Developments in sparse-matrix handling techniques have resulted in the emergence of the network tableau as an important method for a computer solution of network equations. This paper considers the use of the tableau method for the computer-aided design of thyristor circuits and illustrates the method with two examples. The tableau method is described briefly, the problems of sparse-matrix handling, numerical integration and thyristor modelling are introduced.

DOI:10.1049/piee.1979.0091

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The literature giving theoretical analysis and experimental data on arc-back currents in convertor systems is reviewed. An analytical method is recommended, and a solution of the arc-back-current problem in the full form is obtained. Experiments and numerical analyses were carried out and good coincidence of results was obtained.

DOI:10.1049/piee.1979.0092

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The disconnection of an induction motor from its supply, by the interruption of the stator currents as they pass through their zero values, is analysed using permissible approximations. The disconnection by current chopping, of a single motor as well as a group of motors, is also analysed. For a single machine, the rotor currents given by the two analyses are very close even for a small machine, because the difference is determined by the open-circuit, rather than the short-circuit, decrements during the quarter cycle taken for current-zero interruption. Computed results for a small and a medium-sized motor, obtained by numerical integration, are presented to validate the approximate analysis of current-zero disconnection, and to confirm that the transients on reconnection of the machine to the supply are almost independent of the way in which the disconnection takes place. Thus, quite accurate predictions of transients following current-zero disconnection are obtained if current chopping is assumed; this simplifies the computations. It is found that the discrepancies are generally least when a chopping instant μ/6 rad after the current zero is chosen. The general conclusion is that the computationally convenient method based on current chopping is always applicable, whether or not current-zero interruption takes place.

DOI:10.1049/piee.1979.0093

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The paper describes the design and implementation of a new type on nonlinear digital controller. This controller and other comparable ones are evaluated by implementing them on a laboratory microturboalternator system coupled to a minicomputer. Offline theoretical predictions of the system response, based on a comprehensive mathematical model, are presented. The results show that the transient performance of this new controller compares favourably with that of existing digital controllers. A novel nonrecursive solution to the discrete Riccati equation is also demonstrated.

DOI:10.1049/piee.1979.0094

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The paper presents a new method for accurately calculating the torque and current of a variable-reluctance stepping motor from measured or computed flux-linkage/current/rotor position data. The new method is more accurate and uses less input data than previously known procedures, and is computationally efficient. It can be applied to both steady-state and transient problems.

DOI:10.1049/piee.1979.0095

出版商:IEE    

年代:1979

数据来源: IET

摘要:

Trapezoidal rule of integration is used for the computation of impulse-voltage stresses in transformer windings through a companion-network approach. The method is compared with two other methods, one based on eigenvalues and eigenvectors and the other based on series expansion of the state-transition matrix. The method is also verified by comparing it with experimental results.

DOI:10.1049/piee.1979.0096

出版商:IEE    

年代:1979

数据来源: IET

摘要:

In the paper some experimental methods of measuring sequence impedances of a 3-phase delta-star transformer have been developed. Easier methods of predetermining these impedances have also been discussed.

DOI:10.1049/piee.1979.0097

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A synthesis method is described that is used to produce optimised excitation control of an a.c. turbogenerator when subjected to a large disturbance. The proposed controller incorporates only one extra feedback signal into the excitation system in addition to the normal terminal voltage feedback signal, and the relative merits of four such proposed signals are fully discussed. The method uses single-variable optimisation techniques, incorporating successive quadratic or cubic approximations of a nonlinear polynomial, and, by using dynamic sensitivity methods, gives important additional information on the relative suitability of each of the four proposed feedback signals. An experimental investigation performed on a laboratory micromachine system is also described, and confirms the trends in changes in system transient behaviour predicted by the theoretical studies.

DOI:10.1049/piee.1979.0098

出版商:IEE    

年代:1979

数据来源: IET