摘要:

AbstractThis paper considersH∞ control design of a magnetic bearing from the viewpoint of loop shaping. Feedback control is indispensable for a magnetic bearing, since it is essentially an unstable system. For feedback control, a mathematical model is required. However, it does not always express the exact behavior of the system, hence the model has various uncertainties such as the errors of parameters, neglected nonlinearities, or unmodeled dynamics. The controller is needed to guarantee robustness for both stability and performance against these uncertainties on the model.First, based on some assumptions, a linear state space model of a magnetic bearing is shown. Second, the experimental machine and the surroundings of its controller are introduced. The experimental machine is a 4‐axis controlled horizontal shaft magnetic bearing. The controller consists of a digital signal processor with fast A/D converters and D/A converters. Third, the control system is designed using normalized coprime factor plant descriptions. Selecting shaping functions in this procedure called “The Loop‐Shaping Design Procedure (LSDP),” shape the open‐loop transfer function and the transfer functions of the closed‐loop system can be shaped. Finally, several experiments are carried out according to the aforementioned design

ISSN:0424-7760    

DOI:10.1002/eej.4391140111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractTwo design methods of ac/dc thyristor converter current control systems with MRAC (Model Reference Adaptive Control) have been designed. To linearize the input/output relation of the systems, the constant term of the model is considered in different ways. In the first method, a linear transformation of the control input is made while in the second method, the constant term and compensated modeling error are neglected by integral adaptation. Computer simulations and experiments have shown that the control performances of the MRAC systems are much better than that of PI controllers. However, in the first method, since the variable vector is not persistently spanning, the convergence rate of estimated parameters is not as high as expected. The second method has better dynamic characteristics but its stability has not been proved in theory.This paper suggests a new design method in which the constant term is considered as a deterministic disturbance. The feature of this method is that by introducing an equality equation which makes the term of disturbances apparently unobservable, the effect of disturbances can be eliminated and the existing adaptive control scheme without disturbances whose stability has been proved theoretically can be used. Computer simulations and experiments show that the new method can obtain better responses than the old ones.

ISSN:0424-7760    

DOI:10.1002/eej.4391140112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractNumerous studies were performed to evaluate the performance of photovoltaic power systems (PV systems), including maximum power control of the solar cell, effects of the PV systems on distribution feeders, long‐term performance of the PV systems, etc. To estimate the performance of PV systems, the output characteristics of the solar cell should be taken into consideration.This paper proposes a new method of the simulated power source (SPS) to analyze the PV system. The SPS is under the control of the 10 cm2reference solar cell, hence, the output characteristics of the SPS are in proportion not only to the static output characteristics of the reference solar cell, but also the dynamic one

ISSN:0424-7760    

DOI:10.1002/eej.4391140113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY