Showing papers on "Open-loop controller published in 2015"

Methods and systems for converged networking and storage

Abstract: A device includes a converged input/output controller that includes a physical target storage media controller, a physical network interface controller and a gateway between the storage media controller and the network interface controller, wherein gateway provides a direct connection for storage traffic and network traffic between the storage media controller and the network interface controller.

Speed control of Brushless DC motor using bat algorithm optimized Adaptive Neuro-Fuzzy Inference System

Abstract: Bat algorithm optimized online ANFIS based speed controller presented for Brushless DC motor.The speed response of Brushless DC motor is analyzed for different operating conditions.The proposed controller eliminates the uncertainty problem due to load disturbance and set speed variations.The proposed controller enhances the time domain specifications and performance indices in all operating conditions. In this paper, speed control of Brushless DC motor using Bat algorithm optimized online Adaptive Neuro-Fuzzy Inference System is presented. Learning parameters of the online ANFIS controller, i.e., Learning Rate (?), Forgetting Factor (λ) and Steepest Descent Momentum Constant (α) are optimized for different operating conditions of Brushless DC motor using Genetic Algorithm, Particle Swarm Optimization, and Bat algorithm. In addition, tuning of the gains of the Proportional Integral Derivative (PID), Fuzzy PID, and Adaptive Fuzzy Logic Controller is optimized using Genetic Algorithm, Particle Swarm Optimization and Bat Algorithm. Time domain specification of the speed response such as rise time, peak overshoot, undershoot, recovery time, settling time and steady state error is obtained and compared for the considered controllers. Also, performance indices such as Root Mean Squared Error, Integral of Absolute Error, Integral of Time Multiplied Absolute Error and Integral of Squared Error are evaluated and compared for the above controllers. In order to validate the effectiveness of the proposed controller, simulation is performed under constant load condition, varying load condition and varying set speed conditions of the Brushless DC motor. The real time experimental verification of the proposed controller is verified using an advanced DSP processor. The simulation and experimental results confirm that bat algorithm optimized online ANFIS controller outperforms the other controllers under all considered operating conditions.

On the neuro-adaptive feedback linearising control of underactuated autonomous underwater vehicles in three-dimensional space

Abstract: This study addresses the input-output feedback linearisation and the internal dynamics stability of an underactuated autonomous underwater vehicle (AUV) in three-dimensional space. By taking the coordinates of a virtual reference point in front of AUV system as the output equation, the input-output feedback linearisability of AUV kinematics and dynamics is guaranteed. A non-linear controller is designed to make the reference point track a desired trajectory which is generated by an open-loop path planner. Then, it is shown that the resulting internal dynamics of the system is stable. Neural network approximation capabilities and adaptive techniques are also adopted to compensate for unknown vehicle parameters, and constant or time-varying disturbances induced by waves and ocean currents. A Lyapunov-based stability analysis is used to show uniform ultimate boundedness of tracking errors. Finally, simulation results are provided to illustrate the effectiveness of the proposed control system as a qualified candidate for real implementations in offshore applications.

A Fixed-Switching-Frequency Integral Sliding Mode Current Controller for Switched Reluctance Motor Drives

Abstract: A fixed-switching-frequency model-based sliding mode current controller with an integral switching surface for switched reluctance motor (SRM) drives is presented in this paper. Based on the equivalent circuit model of SRM, including the magnetic saturation and mutual coupling, an integral sliding mode current controller is designed. The stability of sliding mode controller is analyzed in two scenarios: 1) one with known motor parameters and 2) the other with bounded modeling error. In order to analyze the robustness of the sliding mode controller, the motor controller parameter constraints are derived and the stability analysis is demonstrated by considering motor parameter modeling errors. The sliding mode controller is validated by both simulation and experimental results with a 2.3-kW, 6000-r/min, three-phase 12/8 SRM over the wide speed range in both linear and magnetic saturation regions. Compared to the hysteresis current controller, the sliding mode controller demonstrates comparable transient response and steady-state response in terms of torque ripples, current ripples, root-mean-square error of current and torque. Moreover, the sliding mode controller has some advantages over the hysteresis controller, including constant switching frequency and much lower sampling rate.

A Robust DC-Link Voltage Control Strategy to Enhance the Performance of Shunt Active Power Filters Without Harmonic Detection Schemes

Abstract: Shunt active power filters $(SAPFs) $ implemented without harmonic detection schemes are susceptible to sudden load variations. This paper proposes a robust control strategy to reduce this drawback. In this strategy, the dc-link voltage is regulated by a hybrid control technique combining a standard proportional–integral $PI$ and a sliding-mode $(SM)$ controllers. The $SM$ scheme continuously determines the gains of the $PI$ controller based on the control loop error and its derivative. The chattering due to the $SM$ scheme is reduced by a transition rule that fixes the controller gains when steady-state condition is reached. This controller is termed as dual-sliding-mode-proportional–integral. The phase currents of the power grid are indirectly regulated by double-sequence controllers with two degrees of freedom, where the internal model principle is employed to avoid reference frame transformation. The proposed control strategy ensures zero steady-state error and improves the performance under hard transients such as load variation. Additionally, it presents robustness when the $SAPF$ is operating under unbalanced conditions. Experimental results demonstrate the performance of the proposed control scheme.

A fractional order fuzzy PID controller for binary distillation column control

Abstract: Realization of a fractional order fuzzy (FOF) PID controller with nonlinear gains.Performance evaluation of FOFPID controller for a binary distillation column.Comparison of this controller with its integer order counterpart.The proposed FOFPID controller was found superior in all aspects. Expert and intelligent control schemes have recently emerged out as a promising solution with robustness which can efficiently deal with the nonlinearities, along with various types of modelling uncertainties, present in different real world systems e.g. binary distillation column. This paper is an attempt to propose an intelligent control system which takes the form of a fractional order fuzzy proportional-integral-derivative (FOFPID) controller which is investigated as a solution to deal with the complex dynamic nature of the distillation column. The FOFPID controller is an extension of an existing formula based self tuning fuzzy proportional integral controller structure, which varies its gains at run time in accordance with the instantaneous error and rate of change of error. The FOFPID controller is a Takagi-Sugeno (TS) model based fuzzy adaptive controller comprising of non-integer order of integration and differentiation operators used in the controller. It has been observed that inclusion of non-integer order of the integration and differentiation operators made the controller scheme more robust. For the performance evaluation of the proposed scheme, the performance of FOFPID controller is compared with that of its integer order counterpart, a fuzzy proportional-integral-derivative (FPID) controller. The parameters of both the controllers were optimized for minimum integral of absolute error (IAE) using a bio-inspired global optimization algorithm, genetic algorithm (GA). Intensive LabVIEW? simulation studies were performed which included setpoint tracking with and without uncertainties, disturbance rejection, and noise suppression investigations. For testing the parameter uncertainty handling capability of the proposed controller, uncertain and time varying relative volatility and uncertain tray hydraulic constant were applied. Also, for the disturbance rejection studies, intensive simulations were conducted, which included two most common causes of disturbance i.e. variation in feed composition and variation in feed flow rate. All the simulation investigations clearly suggested that FOFPID controller provided superior performance over FPID controller for each case study i.e. setpoint tracking, disturbance rejection, noise suppression and parameter uncertainties.

Neural Speed Controller Trained Online by Means of Modified RPROP Algorithm

Abstract: In this paper, the synthesis and the properties of the neural speed controller trained online are presented. The structure of the controller and the training algorithm are described. The resilient backpropagation (RPROP) algorithm was chosen for the training process of the artificial neural network (ANN). The algorithm was modified in order to improve controller operation. The specific properties of the controller, i.e., adaptation and auto-tuning, are illustrated by the results of both simulation and experimental research. An electric drive with permanent magnet synchronous motor (PMSM) was chosen for experimental research, due to its impressive dynamics. The obtained results indicate that the presented controller may be implemented in industrial applications.

Analysis, design and implementation of a quasi-proportional-resonant controller for multifunctional capacitive-coupling grid-connected inverter

Abstract: The capacitive-coupling grid-connected inverter (CGCI) is able to achieve reactive power compensation and active power transfer simultaneously with a low operational voltage. The CGCI is coupled to the point of common coupling (PCC) via a second-order LC circuit, which makes its modeling and current control characteristics differs from the conventional inductive-coupling grid-connected inverter. The direct current tracking with hysteresis pulse width modulation (PWM) was used in previous studies. However, this method suffers from widely varying switching frequency and large current ripples. A Quasi-proportional-resonant (Quasi-PR) current controller is designed for the CGCI in this paper. Its modeling and parameter selection are studied in detail. In contrast with proportional-integration (PI) current controller, the Quasi-PR controller reduces steady-state error. It also generates a voltage reference for applying the carrier-based PWM to improve output waveform quality. Simulation results are provided to verify the Quasi-PR controller and comparison with the PI controller is also done. A lab-scale prototype is built. Experimental results are given to show the validity of the proposed control method and its design.

An Interline DC Power-Flow Controller (IDCPFC) for Multiterminal HVDC System

Abstract: This paper proposes a novel dc power-flow controller for a multiterminal HVDC system, which can be inserted in series on transmission lines to manage the dc power flow. Its key features include: 1) simpler circuit topology; 2) fewer components; and 3) the elimination of an external power supply and low-frequency high-voltage-insulation isolated transformer. A three-terminal HVDC system, including the dc power-flow controller, is studied and its operation principle and characteristics are analyzed. A simulation mode is built to test the feasibility and effectiveness of the proposed dc power-flow controller with cases of power injection step down, power loss of one terminal, and power-flow reversal. A three-terminal dc system is built in the lab to validate the dc power-flow controller. The results show that the proposed dc power-flow controller can enhance the performance and controllability of a multiterminal HVDC system.

Systems and methods for regulating power conversion systems with output detection and synchronized rectifying mechanisms

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal and a second controller terminal. The system controller is configured to receive at least an input signal at the first controller terminal, and generate a gate drive signal at the second controller terminal based on at least information associated with the input signal to turn on or off a transistor in order to affect a current associated with a secondary winding of the power conversion system. The system controller is further configured to, if the input signal is larger than a first threshold, generate the gate drive signal at a first logic level to turn off the transistor.

Solid state power controller.

Abstract: A solid state power controller for switching power on and off to an electrical load which also serves as a circuit protection device protecting the load and/or the wire connected between the load output terminal of the controller and ground from thermal damage due to current overload is shown. When a current overload exists the controller interrupts current to the load in a time inversely proportional to the square of the magnitude of the overload as shown in a trip time vs load current curve. The controller also limits the load current to a selected maximum level by controlling the drain-source resistance of power MOSFETs used for switching the power. A secondary interrupt is provided in the event that the junction temperature of the MOSFETs has risen a selected maximum level. A thermal memory feature is included for both interrupt signals. The controller is controlled by a single on/off input line and provides both a status and trip output line to indicate its state. The status can be configured to monitor load voltage or load current flow as desired. The controller also can be configured to default to either an on or off state in the event the input line is disconnected.

Implementation of adaptive fuzzy logic and PI controllers to regulate the DC bus voltage of shunt active power filter

Abstract: The output gain of the adaptive fuzzy controller (AFC), it is considerate as a fuzzy variable.This gain is adapted as a function of the voltage error and its variation.The comparative at PI controller study, shows that the adaptive fuzzy controller can be enhance the performances the DC voltage control at various operating.Experimental results validate the design methodology. Active power filter (APF) performance is entirely dependent on capacitor voltage. DC voltage optimization is one of the key aspects in harmonics compensation. This paper presents an experimental comparative study of new adaptive fuzzy controller (AFC) and proportional integral (PI) regulator, applied to regulate the DC bus voltage of three phase shunt APF. The proposed AFC for APF, consist to adapt the output gain of this controller at every situation of the system as a function of the voltage error and its variation. The algorithm used to identify the reference currents is based on the Self Tuning Filter (STF). The firing pulses of the insulated-gate bipolar transistors (IGBTs) inverter are generated using a hysteresis current controller; which is implemented on an analog card. Finally, the above study, under steady state and transient conditions, is illustrated with signal-flow graphs and corresponding analysis. This study was verified by experimental tests on hardware prototype based on dSPACE-1104.

Cloud-level control loop tuning analytics

Abstract: A control loop tuning system executing on a cloud platform facilitate remote control system analysis and generation of suitable controller gains for a given closed-loop control application. The system leverages cloud-side analytics and a gain correlation model generated based on historical data collected from the industrial control system and maintained on cloud storage. The gain correlation model creates a virtual association between controller gains and process variables based on operational and configuration data collected from the industrial control system. The system then applies iterative analytics to the model to converge on a set of controller gains determined to satisfy an optimization criterion. The recommended controller gains are then provided to a client device for review and implementation in the real system controller.

Finite-time state-feedback stabilisation of non-holonomic systems with low-order non-linearities

Abstract: This study investigates the problem of finite-time stabilisation by state feedback for a class of non-holonomic systems in chained form with low-order non-linearities, to which the existing control methods are inapplicable. By introducing sign function and necessarily modifying the method of adding a power integrator, a state-feedback controller is successfully constructed. Together with a novel switching control strategy, the designed controller guarantees that the states of closed-loop system are regulated to zero in a finite time. A simulation example is provided to illustrate the effectiveness of the proposed approach.

A Technique to Estimate the Equivalent Loss Resistance of Grid-Tied Converters for Current Control Analysis and Design

Abstract: Rigorous analysis and design of the current control loop in voltage source converters (VSCs) requires an accurate modeling. The loop behavior can be significantly influenced by the VSC working conditions. To consider such effect, converter losses should be included in the model, which can be done by means of an equivalent series resistance. This paper proposes a method to identify the VSC equivalent loss resistance for the proper tuning of the current control loop. It is based on analysis of the closed-loop transient response provided by a synchronous proportional-integral current controller, according to the internal model principle. The method gives a set of loss resistance values linked to working conditions, which can be used to improve the tuning of the current controllers, either by online adaptation of the controller gains or by open-loop adaptive adjustment of them according to prestored data. The developed identification procedure is tested in the laboratory at different specifications of power level and switching frequency.

Hovering in Asteroid Dynamical Environments Using Higher-Order Sliding Control

Abstract: Close-proximity operations around small bodies in general and asteroids in particular are extremely challenging In this paper, we apply the higher-order sliding modes theory to devise a class of discontinuous two-sliding homogeneous controllers for hovering in highly uncertain dynamical environments typically found around asteroids The class of controllers that can be constructed using the higher-order sliding modes theory is shown to be globally finite-time stable against perturbations with a known upper bound The behavior of the proposed two-sliding controller as a function of the design parameters has been analyzed via a set of closed-loop simulations around 433 Eros and 1999 RQ36 Bennu For all cases, the controller is demonstrated to be highly effective in achieving and maintaining the hovering state in spite of perturbing accelerations as well as navigation errors Moreover, it has been demonstrated that the two-sliding controller can be implemented in a bang-off-bang fashion for propellant savin

Effect of Stator Winding Connection of Five-Phase Induction Machines on Torque Ripples Under Open Line Condition

Abstract: One of the main challenges in designing high-power drive systems is the quality of the developed torque. High-torque-ripple magnitudes result in serious vibration and acoustic noise problems that affect the lifetime of a drive train. Multiphase machines intrinsically offer the torque with higher quality and are also being promoted for their high fault tolerant capability when compared with their three-phase counterparts. During open-phase conditions, the induced nonfundamental sequence current components have a detrimental effect on the machine performance especially under open-loop control. Although optimal current control is usually employed to ensure certain optimization criterion, such as minimizing torque ripples, optimizing flux distribution, or minimizing copper loss, are met, it usually entails a sophisticated current controller. This paper studies the effect of a stator winding connection of a five-phase induction machine on the induced torque ripples. Two possible connections, namely, star and pentagon connections are compared under healthy as well as fault conditions with one-line open. The comparison is conducted using both finite-element simulation and experimental results using a 1.5-Hp five-phase prototype induction machine. The comparison shows that the pentagon connection reduces the machine-induced torque ripples and improves the overall machine performance under fault conditions.