Sampling Period Delay Research Articles

Voltage Control of Three-Phase Stand-Alone Photovoltaic System Based on Improved DeadBeat Controller

Stand-Alone Photovoltaic systems (SAP) based on power electronics converters have found high attention, recently. According to the rate of power, three phase inverter is more applicable for high power applications. However, unbalanced loading condition is inevitable condition for these inverters. To prepare a current flow for inevitable fourth wire current, 4-Leg inverter is a beneficial solution. To sinusoidal load voltage shaping, the control method is very important since it must maintain three-phase balanced sinusoidal load voltages. Among different linear and non-linear control methods, deadbeat (DB) method offers high simplicity as well as good accordance for digital implementation. But, it suffers from two sampling period delay which deteriorate the load voltages quality and sometimes, results in instability of the control system. In this paper, new DB control method with delay compensation strategy is proposed which not only have the usual benefits of the DB control method but also, it overcomes the aforementioned weakness. Finally, a 3kW laboratory test bench based on DSP-Based digital control board is provided to consider the result of the proposed control methods. Several tests under various inverter loads such as no load, full linear load and 100% unbalanced load are done to evaluate the benefits of the proposed system.

Systematic design of linear quadratic regulator for digitally controlled grid‐connected inverters

It is a challenging task to design controller for the digitally controlled LCL-filtered grid-connected inverter to achieve high-quality grid current, avoid undesired resonance, and offer robust performance against system parameters uncertainties. To address the problem, in this study, the linear quadratic regulator (LQR) for a digitally controlled grid-connected inverter is proposed. Discrete-time state-space model of the inverter is established by discretising the system continuous state-space equations and taking into account one sampling period delay. Then, a systematic design procedure for selecting the state weighting matrix Q is presented, so that the poles of the closed-loop system are assigned and the desired performances can be achieved. Moreover, to further attenuate the grid voltage background harmonics, the selective harmonic controllers are designed based on the LQR. Compared with the conventional dual current loop control strategy, the proposed LQR controller can achieve low harmonic distortion, fast dynamic response, and good robustness against system parameters deviations. Finally, time-domain simulations are carried out in MATLAB/SIMULINK software and experimental tests are performed on the experimental setup. The results have demonstrated the effectiveness of the proposed LQR method.

Time-Varying Formation Control for Second-Order Discrete-Time Multi-Agent Systems With Directed Topology and Communication Delay

Time-varying formation control protocol design and analysis problems for the second-order discrete-time multi-agent systems with directed interaction topology and communication delay are investigated. A local information-based distributed protocol is designed by utilizing the delayed state information of neighbors. Through system decomposition and stability analysis, an explicit description of the feasible time-varying formation set is given. Necessary and sufficient conditions for the systems with the directed topology and communication delay to achieve time-varying formation are obtained, which are related to the topology of the interaction graph and the feasibility of the predefined formation. Necessary constraints on the gain parameters and the sampling period are proposed, so as to guide the design of parameters in the protocol. The numerical simulation results indicate that the protocol can steer the agents to accomplish the desired time-varying formation and effectively tolerate the relatively large bounded communication delay. Outdoor experiment with quadrotors is presented to demonstrate the effectiveness of the obtained theoretical results with one sampling period delay.

Design of One Sampling Period Delay Stabilizing Controllers for Nonlinear Sampled-data Strict-feedback Systems

We consider the design of one sampling period delay state feedback and output feedback controllers that semiglobally practically uniformly asymptotically (SPUA) stabilize nonlinear sampled-data strict-feedback systems. First we apply nonlinear multi-rate sampled-data control to design one sampling period delay state feedback controllers. Then we derive one sampling period delay output feedback controllers by combining the designed state feedback controllers and reduced-order observers. A numerical example is given to illustrate the proposed design methods.

A Stable Adaptive Control Method in Networked Control System

In this paper it has made study on long time-delay network control system which is greater than one sampling period, it has made modeling on sensor node time drive, controller node and actuator node event-driven system The special question has been considered which was brought more than one sampling period delay, the fuzzy control logic has been applied in MATLAB to design an adaptive Fuzzy controller, when the network time delay changes the controller parameters can be adjusted dynamically, to make dynamic compensation on network time delay, and through simulation experiments to verify the algorithm effectiveness.