The grid-connected three-phase inverter is an indispensable part of the microgrid. The droop control is widely used in parallel inverters for high reliability and flexibility. The output impedance of droop controlled ...
ISBN:
(数字)9781839531248
ISBN:
(纸本)9781839531255
The grid-connected three-phase inverter is an indispensable part of the microgrid. The droop control is widely used in parallel inverters for high reliability and flexibility. The output impedance of droop controlled inverters plays an vital role in its stability. However, the sequence impedance model of grid-connected inverter is currently based on the grid side converter with a single current loop control exdluding the low-frequency dynamics similar in doubly fed induction generators. Both the droop control and voltage loop control greatly affect the stability of inverter, specifically in the low frequency response. This paper proposes a sequence impedance model of inverter, which considers the droop control and voltage and current dual closed-loop control using the harmonic linearization method in the frequency domain. The accuracy of the model is verified through comparing the measurement impedance value in simulation with the impedance value calculated in the sequence impedance model. The influence of control method on system impedance is verified by showing the difference between the single loop controlled inverter and droop control inverter.
With the development of AIoT, data-driven attack detection methods for cyber-physical systems (CPSs) have attracted lots of attention. However, existing methods usually adopt tractable distributions to approximate dat...
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This paper investigates the stabilization problem of a class of fractional order chaotic systems with unknown modeling uncertainties and external perturbations. A fractional nonlinear sliding surface is proposed, and ...
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This paper investigates the stabilization problem of a class of fractional order chaotic systems with unknown modeling uncertainties and external perturbations. A fractional nonlinear sliding surface is proposed, and a reaching control law is obtained to guarantee the stability of the fractional chaotic system in finite time with just a single control input. And the simulation results are given to demonstrate the efficacy of the proposed nonlinear sliding mode control method.
This paper is concerned with the controller design for networked controlsystems(NCSs). A novel eventtriggered networked predictive control scheme is proposed to compensate for the network-induced delay and save netwo...
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ISBN:
(纸本)9781479947249
This paper is concerned with the controller design for networked controlsystems(NCSs). A novel eventtriggered networked predictive control scheme is proposed to compensate for the network-induced delay and save network bandwidth. The closed-loop system is modeled as a switched system with time-varying delay. By constructing a common Lyapunov function, a sufficient stability condition is derived and presented in terms of linear matrix inequalities(LMIs). In order to prove the validity of the proposed method, both a simulation and an experiment are carried out. Both simulation results and experimental results show that this method can compensate for the network-induced delay actively and reduce the burden of the network significantly.
The unmanned aerial vehicles (UAVs) formation needs the frequent data-exchanging of individual's state between units for monitoring and instruction uploading from the ground station, which inevitably occupies huge...
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ISBN:
(数字)9781728133201
ISBN:
(纸本)9781728133218
The unmanned aerial vehicles (UAVs) formation needs the frequent data-exchanging of individual's state between units for monitoring and instruction uploading from the ground station, which inevitably occupies huge communication bandwidth. This paper presents the extended Kalman filter (EKF) design based on the event-triggered strategy to get UAVs greatly relieved of the communication burden with guaranteed accuracy. The event-triggered strategy firstly selects only the state measurements containing innovational information for the purpose of filtering. Due to the nonlinearity of UAV system, the EKF is further applied to make full use of the information from the prior event-trigger strategy so as to enhance the performance of estimation. The proposed algorithm is verified on the physical UAVs regarding the estimation quality and communication rate, demonstrating the robust dynamic performance with effectively reduced communication rate.
In this paper,a time-varying sliding model control(TVSMC) based guidance law against nonmaneuvering targets is proposed with impact angle *** algorithm is first designed for constant-speed interceptors to attack stati...
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ISBN:
(纸本)9781479900305
In this paper,a time-varying sliding model control(TVSMC) based guidance law against nonmaneuvering targets is proposed with impact angle *** algorithm is first designed for constant-speed interceptors to attack stationary and constant-velocity targets,and the global robustness of the system is ***,an adaptation strategy,adaptive time-varying sliding model control(ATVSMC),is adopted to deal with unknown but bounded disturbances by adjusting the switching gain *** analysis of the closed loop system is obtained through Lyapunov ***,numerical simulation results are presented to verify the effectiveness and robustness of the proposed guidance law.
This paper proposes an H polytopic lter design for a nonlinear system. Based on the polytopic approximation of the nonlinear system, the polytopic lter design is converted into a group of linear matrix inequalities(L...
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This paper proposes an H polytopic lter design for a nonlinear system. Based on the polytopic approximation of the nonlinear system, the polytopic lter design is converted into a group of linear matrix inequalities(LMIs) so that the polytopic lter parameters can be effectively acquired by numerical convex optimization algorithms. At this stage, the tensor product(TP) model transformation is utilized to compute the polytopic approximation of the nonlinear system. Particularly, a new recti cation procedure is further developed to obtain a specific polytopic approximation with all the vertex systems being stable, which premises the solvability of the LMIs. The method is much easier to be implemented than traditional approaches such as the Hamilton-Jacobi inequality(HJI)-based methods. Simulation demonstrates the method is much less conservative than the existing method and has good estimation performance.
This paper describes fast test and compensation system for optical encoders. The resolution of system is 0.375", and it can measure the actual accuracy of an optical encoder in four minutes. Furthermore, a method...
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ISBN:
(纸本)9781538629024
This paper describes fast test and compensation system for optical encoders. The resolution of system is 0.375", and it can measure the actual accuracy of an optical encoder in four minutes. Furthermore, a method called Extreme Learning Machine - Fourier Neural Network (ELM-FNN) are proposed to compensate the error. Fourier neural network (FNN) is chosen to fit the curve of the optical encoder's output, and the weights of FNN is calculated by Extreme Learning Machine (ELM). Experimental results demonstrate that ELM-FNN effectively improve the accuracy of the optical encoder. Compared to a back propagation neural network (BP net) and a standard FNN, ELM-FNN has advantages of higher accuracy and less training time.
In this paper, according to the different dynamic models of the support phase and the swing phase, the joint torque compensation of the support phase and the swing phase are given to compensate the joint torque of the...
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ISBN:
(纸本)9781665478977
In this paper, according to the different dynamic models of the support phase and the swing phase, the joint torque compensation of the support phase and the swing phase are given to compensate the joint torque of the hydraulic quadruped robot controlled by the virtual model control(VMC). This compensation can increase the tracking effect of the foot end on the swing trajectory, reduce the elasticity and damping coefficient of the virtual model method, and increase the flexibility of the leg. Then this paper establishes the touchdown detection function based on the joint torque obtained by the Lagrange dynamics equation and the joint torque obtained by the force sensor to determine the touch state of the foot of the quadruped robot to switch the phase of the leg. At the end of this paper, simulation and experiment prove that the compensation model and touchdown detection function model have feasibility and correctness.
The state estimation of general nonlinear systems is investigated through a parameter-dependent approach. This paper adopts the polytopic approximation for the nonlinear systems, which facilitates the application of a...
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ISBN:
(纸本)9781467374439
The state estimation of general nonlinear systems is investigated through a parameter-dependent approach. This paper adopts the polytopic approximation for the nonlinear systems, which facilitates the application of analytical approaches for resultant convex-bounded linear systems into the given nonlinear systems. The design of a high performance H2 state estimator is firstly determined by solving a convex optimization problem constrained by relaxed linear matrix inequalities(LMIs). The tensor product(TP) model transformation is then adopted to obtain the polytopic linearization. Specifically, A new process is presented to correct the result of the TP model transformation such that a necessary condition to solve the state estimation problem is assured. Finally, a numerical simulation is performed to illustrate the design process and verify the performance.
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