scholarly journals A Novel Solution for the Elimination of Mode Switching in Pump-Controlled Single-Rod Cylinders

Actuators ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 20 ◽  
Author(s):  
Petter H. Gøytil ◽  
Damiano Padovani ◽  
Michael R. Hansen
Keyword(s):  
Control Strategy ◽  
Operating Conditions ◽  
Mode Switching ◽  
Loss Of Control ◽  
Unstable Behavior ◽  
Wide Range ◽  
Stability Issue ◽  
Underlying Mechanisms ◽  
The Stability ◽  
Proper Operation

This paper concerns the stability issue of pump-controlled single-rod cylinders, known as mode switching. First, a review of the topic is provided. Thereafter, the most recently proposed solution for the elimination of mode switching is investigated and shown to result in unstable behavior under certain operating conditions. A theoretical analysis is provided demonstrating the underlying mechanisms of this behavior. Based on the analysis, a novel control strategy is proposed and investigated numerically. Proper operation and stability are demonstrated for a wide range of operating conditions, including situations under which the most recently proposed solution results in unstable behavior and loss of control over the actuator.

scholarly journals A Unified Control Strategy of Distributed Generation for Grid-Connected and Islanded Operation Conditions Using an Artificial Neural Network

2021 ◽  
Vol 13 (11) ◽  
pp. 6388
Author(s):  
Karim M. El-Sharawy ◽  
Hatem Y. Diab ◽  
Mahmoud O. Abdelsalam ◽  
Mostafa I. Marei
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Control System ◽  
Distributed Generation ◽  
Control Strategy ◽  
Current Control ◽  
Operating Conditions ◽  
Pi Controllers ◽  
Artificial Neural ◽  
The Stability

This article presents a control strategy that enables both islanded and grid-tied operations of a three-phase inverter in distributed generation. This distributed generation (DG) is based on a dramatically evolved direct current (DC) source. A unified control strategy is introduced to operate the interface in either the isolated or grid-connected modes. The proposed control system is based on the instantaneous tracking of the active power flow in order to achieve current control in the grid-connected mode and retain the stability of the frequency using phase-locked loop (PLL) circuits at the point of common coupling (PCC), in addition to managing the reactive power supplied to the grid. On the other side, the proposed control system is also based on the instantaneous tracking of the voltage to achieve the voltage control in the standalone mode and retain the stability of the frequency by using another circuit including a special equation (wt = 2πft, f = 50 Hz). This utilization provides the ability to obtain voltage stability across the critical load. One benefit of the proposed control strategy is that the design of the controller remains unconverted for other operating conditions. The simulation results are added to evaluate the performance of the proposed control technology using a different method; the first method used basic proportional integration (PI) controllers, and the second method used adaptive proportional integration (PI) controllers, i.e., an Artificial Neural Network (ANN).

scholarly journals Designing Stipulated Gains of Aircraft Stability and Control Augmentation Systems for Semiglobal Trajectories Tracking

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mohamed Mostafa Y. B. Elshabasy ◽  
Yongki Yoon ◽  
Ashraf Omran
Keyword(s):  
Control Method ◽  
Simple Procedure ◽  
Operating Conditions ◽  
Stability And Control ◽  
Wide Range ◽  
Flight Envelope ◽  
The Stability ◽  
Classical Control ◽  
And Control ◽  
Aircraft Stability And Control

The main objective of the current investigation is to provide a simple procedure to select the controller gains for an aircraft with a largely wide complex flight envelope with different source of nonlinearities. The stability and control gains are optimally devised using genetic algorithm. Thus, the gains are tuned based on the information of a single designed mission. This mission is assigned to cover a wide range of the aircraft’s flight envelope. For more validation, the resultant controller gains were tested for many off-designed missions and different operating conditions such as mass and aerodynamic variations. The results show the capability of the proposed procedure to design a semiglobal robust stability and control augmentation system for a highly maneuverable aircraft such as F-16. Unlike the gain scheduling and other control design methodologies, the proposed technique provides a semi-global single set of gains for both aircraft stability and control augmentation systems. This reduces the implementation efforts. The proposed methodology is superior to the classical control method which rigorously requires the linearization of the nonlinear aircraft model of the investigated highly maneuverable aircraft and eliminating the sources of nonlinearities mentioned above.

Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter

2013 ◽  
Author(s):  
Jiaqi Xi ◽  
Qiang Zhang ◽  
Mian Li ◽  
Zhaoguang Wang
Keyword(s):  
Kalman Filter ◽  
Wind Tunnel ◽  
Flow Control ◽  
Extended Kalman Filter ◽  
Control Strategy ◽  
Test Section ◽  
Stagnation Pressure ◽  
Operating Conditions ◽  
Wind Tunnels ◽  
Wide Range

Supersonic wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiment, the stagnation pressure in the test section is required to remain constant. Due to the nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required, which is then capable of properly working under different operating conditions. In this paper, an Extended Kalman Filter (EKF) based flow control strategy is proposed and implemented in the controller. The control strategy is designed based on the state estimation of a real blowdown wind tunnel, which is carried out under an EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the controller parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Jiaqi Xi ◽  
Mian Li ◽  
Qiang Zhang ◽  
Zhaoguang Wang
Keyword(s):  
Kalman Filter ◽  
Flow Control ◽  
Extended Kalman Filter ◽  
Control Strategy ◽  
Test Section ◽  
Initial Conditions ◽  
Stagnation Pressure ◽  
Operating Conditions ◽  
Wind Tunnels ◽  
Wide Range

Supersonic blowdown wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiments, the stagnation pressure in the test section is required to remain constant. Due to nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required for this type of wind tunnels. In this paper, an extended Kalman filter (EKF) based flow control strategy is proposed and implemented. The control strategy is designed based on state estimation of the blowdown process under the EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the control parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

A Mathematical Model and Performance Evaluation for a Single-Stage Grid-Connected Photovoltaic (PV) System

2008 ◽  
Vol 9 (6) ◽  
Author(s):  
Prajna Paramita Dash ◽  
Amirnaser Yazdani
Keyword(s):  
Mathematical Model ◽  
Control Strategy ◽  
Voltage Control ◽  
Current Control ◽  
Operating Conditions ◽  
Single Stage ◽  
Control Loop ◽  
Pv System ◽  
Wide Range ◽  
The Impact

This paper proposes a control strategy for important transients of a single-stage, three-phase, PV system that is connected to a distribution network. The proposed control strategy adopts an inner current-control loop and an outer DC-link voltage control loop. The current-control mechanism renders the PV system protected against external faults, enables control of the DC-link voltage and, therefore, controls/maximizes the PV system power output. The paper also proposes a feed-forward compensation strategy for the DC-link voltage control loop to mitigate the impact of the nonlinear characteristic of the PV array on the closed-loop stability, and to permit design and optimization of the DC-link voltage controller for a wide range of operating conditions. A mathematical model and a control design methodology are presented for the PV system, and it is shown that under the proposed control, the PV system fulfills the operational requirements of a grid-connected PV system. The effectiveness of the proposed control strategy and the most important transients of the PV system are evaluated through simulation studies conducted on a detailed switched model of the PV system in the PSCAD/EMTDC software environment.

scholarly journals Computational Modeling Predicts the Stability of Both Pd+ and Pd2+ Ion-Exchanged into H-CHA

2020 ◽  
Author(s):  
Jeroen Van der Mynsbrugge ◽  
Martin Head-Gordon ◽  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Nearest Neighbor ◽  
Operating Conditions ◽  
Oxidation States ◽  
Vehicle Exhaust ◽  
Reducing Conditions ◽  
Wide Range ◽  
Promising Solution ◽  
The Stability ◽  
Spectroscopy Studies

<p>Passive NO<sub>x</sub> adsorbers (PNA) using Pd/zeolites have emerged as a promising solution for the reduction of cold-start emissions from vehicle exhaust. However, the nature of the active sites and the mechanisms underlying NO<sub>x</sub> adsorption in Pd/zeolites remain a subject of ongoing investigation. In this study, we employ quantum chemical simulations to investigate the structure of Pd species in cation-exchange sites at isolated Al and Al pairs in the 6-ring and 8-ring of the CHA framework, before the introduction of NO<sub>x</sub>. Our calculations show that the speciation of Pd in these exchange sites strongly depends on the precise Al arrangement within the framework, as well as the operating conditions. Ionically dispersed Pd is found to be the most favorable species over a wide range of oxidizing and reducing conditions. Small oligomers of PdO and metallic Pd do not appear to be competitive at either isolated Al or Al pairs. Notably, our calculations show that ion exchange sites other than next-next-nearest neighbor Al pairs in the 6-ring will be preferentially occupied by Pd<sup>+</sup> instead of Pd<sup>2+</sup>. The stability of Pd<sup>+</sup> in the zeolite environment is an interesting contrast with its rareness in molecular Pd compounds. Nonetheless, a detailed analysis of the electronic structure shows that predicted Pd oxidation states are consistent with chemical intuition for all complexes investigated in this study. We also discuss the potential ambiguity in Pd characterization provided by typical experimental techniques such as XANES, EXAFS and UV-VIS, and highlight the need for additional EPR spectroscopy studies to further elucidate the initial Pd speciation in zeolites for PNA applications. </p>

scholarly journals Computational Modeling Predicts the Stability of Both Pd+ and Pd2+ Ion-Exchanged into H-CHA

2020 ◽  
Author(s):  
Jeroen Van der Mynsbrugge ◽  
Martin Head-Gordon ◽  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Nearest Neighbor ◽  
Operating Conditions ◽  
Oxidation States ◽  
Vehicle Exhaust ◽  
Reducing Conditions ◽  
Wide Range ◽  
Promising Solution ◽  
The Stability ◽  
Spectroscopy Studies

<p>Passive NO<sub>x</sub> adsorbers (PNA) using Pd/zeolites have emerged as a promising solution for the reduction of cold-start emissions from vehicle exhaust. However, the nature of the active sites and the mechanisms underlying NO<sub>x</sub> adsorption in Pd/zeolites remain a subject of ongoing investigation. In this study, we employ quantum chemical simulations to investigate the structure of Pd species in cation-exchange sites at isolated Al and Al pairs in the 6-ring and 8-ring of the CHA framework, before the introduction of NO<sub>x</sub>. Our calculations show that the speciation of Pd in these exchange sites strongly depends on the precise Al arrangement within the framework, as well as the operating conditions. Ionically dispersed Pd is found to be the most favorable species over a wide range of oxidizing and reducing conditions. Small oligomers of PdO and metallic Pd do not appear to be competitive at either isolated Al or Al pairs. Notably, our calculations show that ion exchange sites other than next-next-nearest neighbor Al pairs in the 6-ring will be preferentially occupied by Pd<sup>+</sup> instead of Pd<sup>2+</sup>. The stability of Pd<sup>+</sup> in the zeolite environment is an interesting contrast with its rareness in molecular Pd compounds. Nonetheless, a detailed analysis of the electronic structure shows that predicted Pd oxidation states are consistent with chemical intuition for all complexes investigated in this study. We also discuss the potential ambiguity in Pd characterization provided by typical experimental techniques such as XANES, EXAFS and UV-VIS, and highlight the need for additional EPR spectroscopy studies to further elucidate the initial Pd speciation in zeolites for PNA applications. </p>

scholarly journals ANALYSIS OF THE CONDITIONS OF OCCURRENCE AND SUPPRESSION OF LATERAL VIBRATIONS IN MICROWAVE POWER FETS

2020 ◽  
Vol 258 (3) ◽  
pp. 4-21
Author(s):  
V. L. Aronov ◽  
E. M. Savchenko ◽  
D. M. Moseykin ◽  
A. D. Pershin ◽  
D. G. Drozdov
Keyword(s):  
Experimental Studies ◽  
Element Model ◽  
Excitation Power ◽  
Point Of View ◽  
Operating Conditions ◽  
Stability Factor ◽  
Lateral Instability ◽  
Wide Range ◽  
Amplifier Stage ◽  
The Stability

Lateral instability is inherent in power transistors structures, consisting of several simple transistors connected in parallel. The large number of transistor elements complicates the analysis of such instability. The introduction of suppressing resistors makes it possible to prevent the occurrence of lateral oscillations, however there are no unambiguous criteria for achieving stability this way. The matter is further complicated by the fact that transistor exhibits nonlinear operation in a typical amplifier stage, and the operating conditions in many cases correspond to a relatively wide range of frequencies. In this paper, we present an analysis of lateral instability of a power amplifier stage, created on a basis of modern GaN field-effect transistor (FET). We had designed all dies and circuits for this FET. The main feature of the analysis is that we carried it out in the time domain, which made possible to estimate the stability of the stage not only under the excitation power pulse, but also after the end of the pulse. Our approach makes it possible to assess the stability of the amplifier between the excitation pulses, which is very important from the operational point of view. We calculated the estimates of operational stability and stability factor using a simplified transistor model, with the multi-element model reduced to a two-element model. Nevertheless, the results of the estimates retain their significance in real conditions, when the introduction of suppressing resistors creates a significant margin of stability, including the actual operating frequency band of the stage. To date, the data we have obtained after the manufacture of the samples only partially confirms the calculated estimates, due to the complexity of managing the experimental studies. However, there are no recorded results, which deny our estimates for the model.

scholarly journals Design and dSPACE Implementation of a Simplified Fuzzy Control of a DC-DC Three-Level Converter

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Hajar Doubabi ◽  
Issam Salhi
Keyword(s):  
Control Strategy ◽  
Boost Converter ◽  
Operating Conditions ◽  
Operating Range ◽  
Performance Specification ◽  
Output Tracking Control ◽  
Converter Topology ◽  
The Stability ◽  
Level Converter ◽  
Takagi Sugeno

The design of an efficient DC-DC converter depends critically on its suitable control. In this paper, a new simplified output tracking control strategy for a DC-DC three-level boost converter is presented. The proposed strategy is characterized by its good tracking performances, its simplicity of design, and the stability that is ensured over the entire operating range. Thanks to (i) the adopted Takagi–Sugeno (TS) fuzzy approach; (ii) the small-signal model derived under the large domain of operating conditions, and (iii) the proportional-integral (PI) controllers’ merit. After introducing the three-level boost converter topology, the operating principles and mathematical modeling are addressed. Then, the proposed output control strategy is developed based on the PI control and the TS fuzzy approximation. A controller ensuring the capacitor voltages balancing has been also introduced in this paper. Experimental results using dSPACE (DS1104) and a laboratory prototype of three-level boost converter demonstrate the flexibility of the proposed controller, its reference tracking capability, and its ability to satisfy the performance specification over the whole operating range of the system.

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