A new discretization scheme is proposed for the design of a fractional order PID controller. In the design of a fractional order controller the interest is mainly focused on the s-domain, but there exists a difficult ...A new discretization scheme is proposed for the design of a fractional order PID controller. In the design of a fractional order controller the interest is mainly focused on the s-domain, but there exists a difficult problem in the s-domain that needs to be solved, i.e. how to calculate fractional derivatives and integrals efficiently and quickly. Our scheme adopts the time domain that is well suited for Z-transform analysis and digital implementation. The main idea of the scheme is based on the definition of Grünwald-Letnicov fractional calculus. In this case some limited terms of the definition are taken so that it is much easier and faster to calculate fractional derivatives and integrals in the time domain or z-domain without loss much of the precision. Its effectiveness is illustrated by discretization of half-order fractional differential and integral operators compared with that of the analytical scheme. An example of designing fractional order digital controllers is included for illustration, in which different fractional order PID controllers are designed for the control of a nonlinear dynamic system containing one of the four different kinds of nonlinear blocks: saturation, deadzone, hysteresis, and relay.展开更多
The controllability for a class of fractional-order linear control systems is mainly investigated. The generalizations of the usual complete solution formulae of the fractional-order linear control systems are derived...The controllability for a class of fractional-order linear control systems is mainly investigated. The generalizations of the usual complete solution formulae of the fractional-order linear control systems are derived not only for time-invariant case but also for time-varying case. Several sufficient and necessary conditions for state controllability of such systems are established and the corresponding criteria for fractional-order time-invariant continuous-time systems are also obtained. The results obtained will be help for future study of fractional-order control systems.展开更多
The stability of control systems described by fractional-order transfer function form is mainly investigated. The stability analysis of integer-order linear systems was extended to the fractional-order control systems...The stability of control systems described by fractional-order transfer function form is mainly investigated. The stability analysis of integer-order linear systems was extended to the fractional-order control systems. The stability definition of fractional-order linear control systems is presented in terms of the Lyapunov's stability theory. Using the theorems of the Mittag-Leffler function in two parameters directly derives the stability conclusion. The illustrative examples are also given by simulation results.展开更多
A kind of fault diagnosis system of molten carbonate fuel cell (MCFC) stack is proposed in this paper. It is composed of a fuzzy neural network (FNN) and a fault diagnosis element. FNN is able to deal with the informa...A kind of fault diagnosis system of molten carbonate fuel cell (MCFC) stack is proposed in this paper. It is composed of a fuzzy neural network (FNN) and a fault diagnosis element. FNN is able to deal with the information of the expert knowledge and the experiment data efficiently. It also has the ability to approximate any smooth system. FNN is used to identify the fault diagnosis model of MCFC stack. The fuzzy fault decision element can diagnose the state of the MCFC generating system, normal or fault, and can decide the type of the fault based on the outputs of FNN model and the MCFC system. Some simulation experiment results are demonstrated in this paper.展开更多
For environment protection and high efficiency, development of new conceptpower plant has been required in China. The fuel cell is expected to be used in a power plant as acentralized power Station or distributed powe...For environment protection and high efficiency, development of new conceptpower plant has been required in China. The fuel cell is expected to be used in a power plant as acentralized power Station or distributed power plant. It is a chemical power generation device thatconverts the energy of a chemical reaction directly into electrical energy and not limited by Carnotcycle efficiency. The molten carbonate fuel cell (MCFC) power plant has several attractive featuresi.e. high efficiency and lower emission of NO_x and SO_x A combined cycle generation system withMCFC and steam turbine is designed. Its net electrical efficiency LHV is about 55 percent.展开更多
The operating temperature of PEMFC stack is a very important control parameter. In operating process, electro-chemical reaction and the humidity of proton exchange membrane vary sensibly with it, the variation of oper...The operating temperature of PEMFC stack is a very important control parameter. In operating process, electro-chemical reaction and the humidity of proton exchange membrane vary sensibly with it, the variation of operating temperature has a significant influence on the output performance and lifespan of fuel cells. The most existing PEMFC mathematical models are too complicated to apply in on-line control process, so it is necessary to find a simple accurate stable control method. In this paper, a novel genetic algorithm (NGA) is presented, which possesses stronger global searching and local optimizing capacities than SGA. NGA is applied to optimize rapidly the weights of neural network according to the population of excellent individuals, neural networks technique is used to establish a self-adjusted control model for PEMFC system. The results of simulation and experiment are given in the end.展开更多
A novel variable structure control (VSC) with new rapid-smooth reaching law (RSRL) and new rapid-convergent sliding mode (FCSM) is proposed, which is based on analysis of normal VSC system. When it is used for an MIMO...A novel variable structure control (VSC) with new rapid-smooth reaching law (RSRL) and new rapid-convergent sliding mode (FCSM) is proposed, which is based on analysis of normal VSC system. When it is used for an MIMO nonlinear system, we combine the method of Input/Output linearizing (I/O L) with VSC. After analyzing the robustness of the MIMO nonlinear system, we use this novel controller for Precision One Robot position control system. Simulation provides a quite satisfactory performance with uncertainties and external disturbances.展开更多
文摘A new discretization scheme is proposed for the design of a fractional order PID controller. In the design of a fractional order controller the interest is mainly focused on the s-domain, but there exists a difficult problem in the s-domain that needs to be solved, i.e. how to calculate fractional derivatives and integrals efficiently and quickly. Our scheme adopts the time domain that is well suited for Z-transform analysis and digital implementation. The main idea of the scheme is based on the definition of Grünwald-Letnicov fractional calculus. In this case some limited terms of the definition are taken so that it is much easier and faster to calculate fractional derivatives and integrals in the time domain or z-domain without loss much of the precision. Its effectiveness is illustrated by discretization of half-order fractional differential and integral operators compared with that of the analytical scheme. An example of designing fractional order digital controllers is included for illustration, in which different fractional order PID controllers are designed for the control of a nonlinear dynamic system containing one of the four different kinds of nonlinear blocks: saturation, deadzone, hysteresis, and relay.
文摘The controllability for a class of fractional-order linear control systems is mainly investigated. The generalizations of the usual complete solution formulae of the fractional-order linear control systems are derived not only for time-invariant case but also for time-varying case. Several sufficient and necessary conditions for state controllability of such systems are established and the corresponding criteria for fractional-order time-invariant continuous-time systems are also obtained. The results obtained will be help for future study of fractional-order control systems.
文摘The stability of control systems described by fractional-order transfer function form is mainly investigated. The stability analysis of integer-order linear systems was extended to the fractional-order control systems. The stability definition of fractional-order linear control systems is presented in terms of the Lyapunov's stability theory. Using the theorems of the Mittag-Leffler function in two parameters directly derives the stability conclusion. The illustrative examples are also given by simulation results.
文摘A kind of fault diagnosis system of molten carbonate fuel cell (MCFC) stack is proposed in this paper. It is composed of a fuzzy neural network (FNN) and a fault diagnosis element. FNN is able to deal with the information of the expert knowledge and the experiment data efficiently. It also has the ability to approximate any smooth system. FNN is used to identify the fault diagnosis model of MCFC stack. The fuzzy fault decision element can diagnose the state of the MCFC generating system, normal or fault, and can decide the type of the fault based on the outputs of FNN model and the MCFC system. Some simulation experiment results are demonstrated in this paper.
基金This project is supported by National Natural Science Foundation of China (No.50206012).
文摘For environment protection and high efficiency, development of new conceptpower plant has been required in China. The fuel cell is expected to be used in a power plant as acentralized power Station or distributed power plant. It is a chemical power generation device thatconverts the energy of a chemical reaction directly into electrical energy and not limited by Carnotcycle efficiency. The molten carbonate fuel cell (MCFC) power plant has several attractive featuresi.e. high efficiency and lower emission of NO_x and SO_x A combined cycle generation system withMCFC and steam turbine is designed. Its net electrical efficiency LHV is about 55 percent.
文摘The operating temperature of PEMFC stack is a very important control parameter. In operating process, electro-chemical reaction and the humidity of proton exchange membrane vary sensibly with it, the variation of operating temperature has a significant influence on the output performance and lifespan of fuel cells. The most existing PEMFC mathematical models are too complicated to apply in on-line control process, so it is necessary to find a simple accurate stable control method. In this paper, a novel genetic algorithm (NGA) is presented, which possesses stronger global searching and local optimizing capacities than SGA. NGA is applied to optimize rapidly the weights of neural network according to the population of excellent individuals, neural networks technique is used to establish a self-adjusted control model for PEMFC system. The results of simulation and experiment are given in the end.
文摘A novel variable structure control (VSC) with new rapid-smooth reaching law (RSRL) and new rapid-convergent sliding mode (FCSM) is proposed, which is based on analysis of normal VSC system. When it is used for an MIMO nonlinear system, we combine the method of Input/Output linearizing (I/O L) with VSC. After analyzing the robustness of the MIMO nonlinear system, we use this novel controller for Precision One Robot position control system. Simulation provides a quite satisfactory performance with uncertainties and external disturbances.
