A.J. Calderón

Fractional order control strategies for power electronic buck converters

This paper presents several alternative methods for the control of power electronic buck converters applying fractional order control (FOC). For achieving this goal, the controller design will be carried out by two strategies. On the one hand, the design of a linear controller for the DC/DC buck converter will be considered. In that sense, the Bodes ideal function will be used as reference system. On the other hand, the fractional calculus is proposed in order to determine the switching surface applying a fractional sliding mode control (FRSMC) scheme to the control of such devices. In that sense, switching surfaces based on fractional order PID and PI structures are defined. An experimental prototype has been developed and the experimental and simulation results confirm the validity of the proposed control strategies.

Analysis of the Van der Pol Oscillator Containing Derivatives of Fractional Order

In this paper a modified version of the classical Van der Pol oscillator is proposed, introducing fractional-order time derivatives into the state-space model. The resulting fractional-order Van der Pol oscillator is analyzed in the time and frequency domains, using phase portraits, spectral analysis and bifurcation diagrams. The fractional-order dynamics is illustrated through numerical simulations of the proposed schemes using approximations to fractional-order operators. Finally, the analysis is extended to the forced Van der Pol oscillator.

Fractional PID Controllers for Industry Application. A Brief Introduction

In recent years the increasing amount of work related to the application of Fractional Calculus (FC) is remarkable in many areas of science and engineering. In relation to automatic control, the use of Fractional Order Control (FOC) needs, for real applications, to develop methods for controller design and parameter tuning, and efficient strategies for controller implementation. On the other hand, the Proportional Integral Derivative (PID) controller is currently by far the most widely used form of feedback controller in industrial applications. This paper, after an introduction to FC and FOC, briefly presents methods for fractional PID controller tuning, including auto-tuning, and some software and hardware strategies for efficient implementations of controllers in industrial applications.

The fractional order lead compensator

In this paper the fractional order lead compensator (FOLC) is discussed, which, with respect to the traditional lead compensator, introduces a new parameter, alpha, the fractional order of the structure. Two methods are proposed for the design, one of them analytical and the other graphical. The analytical one forces the condition that the compensator gives its maximum phase, phim at the gain crossover frequency, omega m The graphical one allows the use of a graphical criterion for the obtaining of the parameters of the FOLC. This criterion is based on the lead regions defined for the compensator in the complex plane, depending on the value of alpha. This second method allows a flexible and direct selection of the parameters of the fractional structure, taking into account considerations of robustness and overphase. An illustrative example of application is presented and simulation results show the effectiveness of the proposed methods of design

AUTO-TUNING OF FRACTIONAL LEAD-LAG COMPENSATORS

Abstract In this paper, a method for auto-tuning of a fractional order lead-lag compensator using relay feedback tests is proposed. A design method for this kind of compensators is discussed, based on the magnitude and phase measurement of the plant to be controlled from relay feedback tests at a frequency of interest. Simple relationships among the parameters of this fractional controller are established and specifications such as the static error constant (kss), phase margin (φm) and gain crossover frequency (ωc) can be fulfilled, with a robustness argument by inspecting the flatness of phase Bode plot of the compensator. The auto-tuning method proposed can be taken as a first step for a latter generalization of these lead-lag compensators to the fractional PIΛDμ controllers.

Using Fractional Calculus for Lateral and Longitudinal Control of Autonomous Vehicles

Here it is presented the use of Fractional Order Controllers (FOC) applied to the path-tracking problem in an autonomous electric vehicle. A lateral dynamic model of a industrial vehicle has been taken into account to implement conventional and Fractional Order Controllers. Several control schemes with these controllers have been simulated and compared . First, different controllers with similar parameters have been implemented and then they have been improved by using optimization methods. The preliminary results are presented here.

Easy Handling of Sensors and Actuators over TCP/IP Networks by Open Source Hardware/Software

There are several specific solutions for accessing sensors and actuators present in any process or system through a TCP/IP network, either local or a wide area type like the Internet. The usage of sensors and actuators of different nature and diverse interfaces (SPI, I2C, analogue, etc.) makes access to them from a network in a homogeneous and secure way more complex. A framework, including both software and hardware resources, is necessary to simplify and unify networked access to these devices. In this paper, a set of open-source software tools, specifically designed to cover the different issues concerning the access to sensors and actuators, and two proposed low-cost hardware architectures to operate with the abovementioned software tools are presented. They allow integrated and easy access to local or remote sensors and actuators. The software tools, integrated in the free authoring tool Easy Java and Javascript Simulations (EJS) solve the interaction issues between the subsystem that integrates sensors and actuators into the network, called convergence subsystem in this paper, and the Human Machine Interface (HMI)—this one designed using the intuitive graphical system of EJS—located on the user’s computer. The proposed hardware architectures and software tools are described and experimental implementations with the proposed tools are presented.

A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells

In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.

Novel networked remote laboratory architecture for open connectivity based on PLC-OPC-LabVIEW-EJS integration : application in remote fuzzy control and sensors data acquisition

In this paper the design and implementation of a network for integrating Programmable Logic Controllers (PLC), the Object-Linking and Embedding for Process Control protocol (OPC) and the open-source Easy Java Simulations (EJS) package is presented. A LabVIEW interface and the Java-Internet-LabVIEW (JIL) server complete the scheme for data exchange. This configuration allows the user to remotely interact with the PLC. Such integration can be considered a novelty in scientific literature for remote control and sensor data acquisition of industrial plants. An experimental application devoted to remote laboratories is developed to demonstrate the feasibility and benefits of the proposed approach. The experiment to be conducted is the parameterization and supervision of a fuzzy controller of a DC servomotor. The graphical user interface has been developed with EJS and the fuzzy control is carried out by our own PLC. In fact, the distinctive features of the proposed novel network application are the integration of the OPC protocol to share information with the PLC and the application under control. The user can perform the tuning of the controller parameters online and observe in real time the effect on the servomotor behavior. The target group is engineering remote users, specifically in control- and automation-related tasks. The proposed architecture system is described and experimental results are presented.

Management of a PEM Electrolyzer in Hybrid Renewable Energy Systems

“In this work, the design, configuration, and results, under real conditions of a fuzzy logic controller to manage a PEM electrolyzer are presented. The output of the fuzzy controller determines, in real-time, the operation point of the electrolyzer according to energetic and technological requirements. The controller has been designed with the Fuzzy Logic Toolbox of Matlab, and runs in Simulink. The control structure integrates the fuzzy controller and the PLC responsible for global management of the installation using OPC technology. This structure presents versatility and ability to serve as platform to test different fuzzy controller configuration”.