摘要:

Recent work on the use of discrete first-order approximate models of plant dynamics in multi-variable process control is extended to consider the effect on transient performance of nonhinearities, such as measurement quantisation or dead-zone at the implementation stage. Explicit upper bounds on the transient error induced by the nonlinearity are obtained and their validity illustrated by numerical examples. In particular, at fast sampling rates, it is seen that, not only does the first-order controller produce a closed-loop system with rapid, nonoscillating responses and small interaction effects, but it also ensures that peak transient errors owing to the nonlinearity are less than the error involved in approximating the nonlinearity by a unity gain matrix. For example, if the nonlinearity is measurement quantisation, the peak transient effects of the quantisation will be bounded by the quantisation error itself at fast sampling rates, and will not be amplified by system dynamics.

DOI:10.1049/ip-d.1980.0007

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The paper presents a method of determining the parameters of a process described by a partial differential equation from a knowledge of its solution. The development is based on treating the process signals as multidimensional distributions in the manner established by Laurent Schwartz, and expanding them in an exponentially weighted series of the generalised partial derivatives of the multidimensional Dirac delta function, termed as the Poisson moment functional ( p. m. f. ) expansion. The ability of the method is successfully demonstrated in the presence of noise.

DOI:10.1049/ip-d.1980.0008

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The phase-locked-loop technique has many advantages when applied to speed control. However, there is the problem of controlled operation outside lock conditions when a variable-frequency induction motor is used. The paper proposes the application of a slip-frequency limit circuit in the forward loop to overcome this problem. Experimental results are provided in support of this method.

DOI:10.1049/ip-d.1980.0009

出版商:IEE    

年代:1980

数据来源: IET

摘要:

The solution of the l. q. g. regulator problem is given by the separation principle and involves a Kalman filter with the same dimension as that of the plant. It is shown that, for a class of systems where the input subsystem states are measurable, the Kalman filter may be reduced in dimension considerably. An example of a steel-mill shape control problem is discussed where the number of states required in the filter is halved. The proposed optimal system includes direct state-feedback from the measurable states, which improves the performance of the system and reduces the effects of modelling errors.The optimal controller for the discrete-time system is derived in thez-domain. The solution of the above multivariable regulator problem has not previously been obtained in this form. Thez-domain controller is particularly suitable for implementation on a microprocessor or digital computer.

DOI:10.1049/ip-d.1980.0010

出版商:IEE    

年代:1980

数据来源: IET

摘要:

Open-loop transfer functions are presented for various a. c. magnetic suspension systems. These transfer functions, relating changes in control voltage to changes in airgap, are used to demonstrate the differences between the various a. c. magnetic suspension systems and to show the effect of parameter variation (such as airgap or carrier frequency) on the open-loop poles and zeros. The transfer functions developed are used in a closed-loop linear model to predict the transient behaviour of an experimental system. Several different compensations and frequencies are used.LCRtuned-circuit as well asRLcircuit-suspension systems are analysed. Good agreement is achieved for natural frequencies, gains and damping.

DOI:10.1049/ip-d.1980.0011

出版商:IEE    

年代:1980

数据来源: IET

摘要:

A conventional optimal controller and an optimal controller to ensure a prescribed degree of stability are designed for ad-qmachine connected to a large power system through a long transmission line. The inherent reduced sensitivity of the optimal controller for plant parameter variations, with a prescribed degree of stability, results in a fixed controller to cover the complete spectrum of operating conditions of the power system under steady state.

DOI:10.1049/ip-d.1980.0012

出版商:IEE    

年代:1980

数据来源: IET