Showing papers presented at "International Symposium on Industrial Electronics in 2006"

Improved MPPT method for rapidly changing environmental conditions

Abstract: A well-known limitation of the Perturb and Observe (P&O) MPPT method is that it can get confused and track in wrong direction during rapidly changing irradiation. The present work offers a simple and effective solution to this problem, by using an additional measurement of the solar array's power in the middle of the MPPT sampling period. The method has been experimentally tested and compared with the traditional P&O method.

Indirect Adaptive Control of an Electro-Hydraulic Servo System Based on Nonlinear Backstepping

Abstract: This paper studies the position control of an electro-hydraulic servo system using indirect adaptive Backstepping. In fact, electro-hydraulic systems are known to be highly nonlinear and non-differentiable due to many factors as leakage, friction and especially the fluid flow expression through the servo-valve. Backstepping is used here for being a powerful, robust nonlinear strategy and for its ability to ensure a global asymptotic stability of the controlled system without canceling useful nonlinearities. On the other hand, hydraulic parameters such as fluid viscosity and bulk modulus are subjected to variations due to temperature rise. This results in a variation of the viscous friction coefficient. Knowing that the structure of a Backstepping controller relies on the system parameters, it is crucial to use adaptive Backstepping in order to update the controller structure with parameters variation. Emphasis is also on the tuning parameters effect and their influence on the errors dynamic behavior, in addition to the chattering and saturation in the control signal. Results in this work are based on simulations and are compared to those obtained with non-adaptive Backstepping. We will see the effectiveness of the proposed approach in terms of guaranteed stability and zero tracking error in the presence of varying parameters.

Control Strategies for Distributed Power Generation Systems Operating on Faulty Grid

Abstract: The distributed power generation based on renewable energy sources such as wind and sun experiences a high penetration in the power systems around the world, having in some countries a large contribution to the total energy production. In order to protect the distribution and transmission systems, the grid operators are more and more talking about the ability of the distribution systems (mainly wind turbines WT systems) to behave as a conventional power plant. This paper discusses the possibilities of the distributed power generation systems (DPGS) to deliver power when grid disturbances are present in the utility network. The focus is set more on the control strategies for active power generation, and mainly on the creation of the reference currents which fulfill the demanded output power. Considerations about reactive power are also stated. Experimental results are presented in order to validate the theory behind the proposed control strategies on faulty grid.

Output Power Maximization of a Permanent Magnet Synchronous Generator Based Stand-alone Wind Turbine

Abstract: This paper proposes output power maximization control of wind energy system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed wind energy system. In order to achieve the maximum power control of wind turbine across a wide range of wind speeds, a dynamic modeling and simulation of wind system with battery energy storage including wind disturbances is presented in this paper. This model should be able to support the analysis of the interaction between the mechanical structure of the wind turbine and the electrical load during different operational modes. These wind turbine concept models can be used and even extended for the study of different aspects, e.g. the assessment of power quality, control strategies, connection of the wind turbine at different types of grid and storage systems.

Basic Criteria in Designing LCL Filters for Grid Connected Converters

Abstract: The presence of Distributed Resources (DR) and the subject of Distributed Generation (DG) are rapidly growing in modern distribution networks. Many of these resources use renewable energies, and many of them provide electrical energy in the form of dc voltage source. Consequently, the connection of such resources to the utility grid needs a dc/ac conversion stage. Voltage Source Converters (VSC) are widely used for this application as they have a mature technology. These converters are usually connected to the utility grid through a simple L filter to reduce the current harmonics injected to the grid. However, higher order filters, like LCL filters, can provide better harmonic attenuation and reduce the filter size at the same time. This paper is concerned with the subject of grid connected converters via LCL filter topology. The advantages of using LCL filter as compared to simple L filter are discussed. Mathematical expressions and plots are given to show the performance of these filters. The design criteria are stated. Different design issues like the total size of magnetic components, ripple current and filter resonant frequency are addressed. Design guidelines are given for optimal selection of filter components.

Modulation Strategies for Fault-Tolerant Operation of H-Bridge Multilevel Inverters

Abstract: The operation of the H-bridge multilevel inverter under fault conditions is examined in this paper. In the event of a fault, the cell with problems can be bypassed to enable the operation of the inverter with fewer cells. This approach could result in an unbalanced inverter configuration which can be corrected by modifying the modulation scheme. Two different approaches based on the Phase Shift-PWM (PS-PWM) and the Space Phasor Modulation (SPM) are considered to compensate the voltage unbalance. Aspects such as the firing pulses generation and the use of optimal sequences are also discussed. The feasibility of the method will be demonstrated using simulated as well as experimental results in a 5-level H-bridge multilevel inverter.

A High Step-Up DC-DC Converter Based on Three-State Switching Cell

Abstract: A new non-isolated boost converter with high voltage gain is proposed on this work This converter is suitable for applications with a high voltage gain between the input and the output In this converter, for a given duty cycle, the output to input voltage ratio can be raised by adding transformer turns Another important feature of this converter is the lower blocking voltage across the controlled switches compared to similar circuits, which allows the utilization of MOSFETs switches with lower conduction resistances RDS(on) In order to verify the feasibility of this topology; principle of operation, theoretical analysis, and experimental waveforms are shown for a 1 kW assembled prototype

Fuel Cell Technology for Distributed Generation: An Overview

Abstract: Fuel cell technology for distributed generation (DG) is attracting more and more attention due to its high efficiency and unique environmentally friendly features. In this paper, the system characteristics, state-of-the-art, prospective markets and applications of different fuel cells are discussed. The operational principles of these fuel cell systems are also presented and their distinct characteristics are summarized. As a new technology for DG, this paper focuses more attention on the DG application aspect of fuel cells. Comparison of different type of fuel cells in the framework of DG is also made. Furthermore, the power conditioning and control techniques for fuel cell based DG are also reviewed. Finally, future prospects of fuel cell based DG are predicted.

Conceptual Study of Unified Power Quality Conditioner (UPQC)

Abstract: This paper deals with conceptual study of unified power quality conditioner (UPQC) during voltage sag and swell on the power distribution network. One of the peculiarities of UPQC is that it can inject voltage from 0deg to 360deg. Based on this injected voltage phase angle with respect to the utility or PCC voltage phase angle, UPQC can absorb or inject active power. Thus the UPQC can work in zero active power consumption mode, active power absorption mode and active power delivering mode. The series active power filter (APF) part of UPQC works in active power delivering mode and absorption mode during voltage sag and swell condition, respectively. The shunt APF part of UPQC during these conditions helps series APF by maintaining dc link voltage at constant level. In addition to this the shunt APF also compensates the reactive power required by the load and harmonics generated by them. The MATLAB / SIMULINK results are provided in order to verify the analysis

Hardware-In-the-Loop Simulation of Finite-Element Based Motor Drives with RT-LAB and JMAG

Abstract: This paper presents a new development in the field of design process and testing of motor drives, for hardware-in-the-loop (HIL) applications. It consists of implementing the finite element (FE) method applied to electric motors on a real-time simulator; coupled with circuit simulation, this enables accurate real-time simulation of the complete motor drive, including the inverter and the motor. The paper describes the integration of FE-based motor model generated by JMAGreg software, with the high-end real-time RT-LABreg simulator. The complete solution consists of combining accurate FE-based motor model, with inverter model, including important switching parameters, all constructed in the Simulinkreg environment, and simulated on PC-based RT-LAB simulation platform, using ultra-fast processors and FPGA-based inputs/outputs (I/O) boards. By connecting the real-time simulator to an external controller under test, this allows high fidelity HIL simulation of motor drives and enables the design engineers to test the system and the controller with a very accurate, FE-based motor model running in real-time

NTP versus PTP in Com puter Networks Clock Synchronization

Abstract: Trusted and precise time sources are required in computer networks and Internet for various reasons: time stamps for electronic documents, online transactions, storage and document retrieval, electronic mail, multimedia applications and many others. Also, the demand for Ethernet as a real-time control network is increasing, as manufacturers realize the benefits of employing a single network technology across the plant. For control and measurement applications, the need of an accurate distribution-wide sense of time is even more stringent than regular applications. This paper is comparing two clock synchronization protocols, the Network Time Protocol and the IEEE-1588 Precision Time Protocol. It gives an overview of synchronization methods by the time stamping employed in IP-based real-time applications looking at the possible sources of errors as well as the achievable performance of the two standards.

Recognition of Grip-Patterns by Using Capacitive Touch Sensors

Abstract: A novel and intuitive way of accessing applications of mobile devices is presented. The key idea is to use grip-pattern, which is naturally produced when a user tries to use the mobile device, as a clue to determine an application to be launched. To this end, a capacitive touch sensor system is carefully designed and installed underneath the housing of the mobile device to capture the information of the user's grip-pattern. The captured data is then recognized by a minimum distance classifier and a naive Bayes classifier. The recognition test is performed to validate the feasibility of the proposed user interface system.

Real-Time Simulation of Permanent Magnet Motor Drive on FPGA Chip for High-Bandwidth Controller Tests and Validation

Abstract: This paper presents a real-time simulator of a permanent magnet synchronous motor (PMSM) drive implemented on an FPGA card. Real-time simulation of PMSM drives enables rapid deployment and thorough testing of efficient control strategies for vehicular or industrial applications. The PMSM model is based on Park transform with a reference frame on the rotor and assumes sinusoidal flux induction. The PMSM machine in driven by a 3-phase IGBT inverter. Both models are implemented in RT-LAB using a Simulink blockset called Xilinx System Generator (XSG), without any VHDL coding. The paper will explain various aspects of the design of the motor drive models in fixed-point representation in XSG, as well as actual simulation validations against a standard PMSM drive model built in Simulink. The PMSM drive is coded along with a test PWM source, built-in the FPGA, with user selectable dead-time, modulation index, source angle offset and frequency. The overall model compilation and simulation is made entirely automatic under the RT-LAB real-time simulation platform. The drive can also run in closed loop with a controller executed on a CPU of the real-time simulator. The final PMSM drive model runs with a 20 ns integration time step, allows for time multiplexing of d-q values and has an input-output latency of 310 ns (250 ns for the PMSM machine alone). The drive is directly connected to RT-LAB digital input and analog outputs (1 microsecond settling time) on the FPGA card and has a resulting total HIL latency of 1.31 microseconds.

Selective Harmonic Elimination for a Cascade Multilevel Inverter

Abstract: This paper presents selective harmonic elimination method for cascade multilevel converters to eliminate the specified harmonics in the output voltage. The principle of the converter is analyzed. Then the switching angles are computed to eliminate the low order harmonics in theory. And the gating signals for the converter are given. An experimental 7-level H-bridge multilevel converter was used to implement the algorithm and to validate the methods. The experimental results show that the method can effectively eliminate the specific harmonics as expected.

Vehicle Lateral Control and Yaw Stability Control through Differential Braking

Abstract: This paper examines the effectiveness of a brake-by-wire system with the uses of differential brake torque for lateral control and yaw stability control in the context of Intelligent Vehicle Highway Systems. Differential braking easily realized by the brake-by-wire system can generate the vehicle yaw moment. The resulting yaw moment affects vehicle lateral position and yaw rate, thereby providing a limited steering function. The steering function achieved through BBW system can then be used to control lateral position in an unintended road departure system. A 7-DOF model is developed to capture the vehicle longitudinal, lateral and yaw motion, and the other four degrees of motion representing the wheel dynamics. Since the 7-DOF model is rather complicated for controller design, a linearized vehicle model is presented for the explanation of the idea of differential braking and for the control design. A fuzzy logic controller is developed to explore the feasibility and capability of BBW systems for lateral control and yaw stability control. Simulation results on the nonlinear vehicle model are used to illustrate the effectiveness of the fuzzy logic control approach for lateral control and yaw stability control with differential braking.

Design Considerations of a Straight Bladed Darrieus Rotor for River Current Turbines

Abstract: Hydrokinetic turbines convert kinetic energy of moving river or tide water into electrical energy. In this work, design considerations of river current turbines are discussed with emphasis on straight bladed Darrieus rotors. Fluid dynamic analysis is carried out to predict the performance of the rotor. Discussions on a broad range of physical and operational conditions that may impact the design scenario are also presented. In addition, a systematic design procedure along with supporting information that would aid various decision making steps are outlined and illustrated by a design example. Finally, the scope for further work is highlighted.

A Simple Switch Selection State for SVM Direct Power Control

Abstract: This work presents a simple scheme for vector selection in Direct Power Control (DPC) in a three-phase rectifier without the use of switch selection tables. The method is simulated using a C language description of the system and its results are later verified on an experimental test rig. Additional states are obtained using Space Vector Modulation (SVM) which reduce the hysteresis band of the active and reactive power controller.

Fault Diagnostic in Power System Using Wavelet Transforms and Neural Networks

Abstract: This paper presents a new approach to Fault detection and diagnosis in power system. Discrete wavelet transformations (DWT) combined with neural networks (NN) have been applied to a typical three phase inverter. A set of faults have been examined, such as inverter IGBT open-circuit fault, leg open fault. The input signals of this algorithm are the three-phase stator currents. Identification and classification uses approximation and details at levels 6 of these currents. The results of simulation show that the proposed technique can accurately detect identify and classify effectively the faults of interest in the power system.

Proposal of a New High Step-Up Converter for UPS Applications

Abstract: This paper proposes the use of a voltage doubler rectifier as the output stage of an interleaved boost converter with coupled inductors. The obtained voltage gain is twice that of traditional boost converters due to the doubler stage, as coupled inductors provide additional voltage gain, although voltage stress across the switches is not increased. The resulting topology is adequate for battery sourced systems which require low current ripple and high voltage gain e.g. UPS's and audio amplifiers. Additionally, it can be used to obtain symmetrical power supply. Theoretical analysis and experimental results from a 1 kW prototype are shown

Static Var Compensator and Active Power Filter with Power Injection Capability, Using 27-level Inverters and Photovoltaic Cells

Abstract: An active power filter and static VAR compensator with active power generation capability, has been implemented using a 27-level inverter. Each phase of this inverter is composed of three "H" converters, all of them connected to the same dc link and their outputs connected through output transformers scaled in power of three. The Filter can compensate load currents with high harmonic content and low power factor, resulting in sinusoidal currents from the source. The dc link is connected to a battery pack, which can be charged from two sources: the ac mains supply and a photovoltaic array connected to the batteries through a MPT (Maximum Power Tracker) converter. These characteristics make it possible to produce active power and to feed the contaminating load during prolonged voltage outages. Simulation results for this application are shown and some experiments with a 3 kVA device are also displayed.

The Effect of Interline Power Flow Controller (IPFC) on Damping Inter-area Oscillations in the Interconnected Power Systems

Abstract: The effect of Interline Power Flow Controller (IPFC) on damping low frequency oscillations has implied in some papers, but has not investigated in details. This paper investigates the damping control function of an Interline Power Flow Controller installed in a power system. For this purpose, Single Machine-Infinite Bus model integrated with IPFC is used, and the linearized model is established. Using this model, Phillips-Heffron model of system for steady state digital simulations is derived. In this paper, numerical results with Matlab Simulink toolbox, which show the significant effect of IPFC on damping inter-area oscillations, are represented.

Contactless Energy Transfer to a Moving Load Part I: Topology Synthesis and FEM simulation

Abstract: In this paper a new topology for contactless energy transfer is proposed that can transfer energy to a moving load using inductive coupling. The load is attached to a planar motor that is magnetically levitated and propelled by the same coils that transfer energy to the moving load. The proposed coil geometry is very tolerant to misalignments of the secondary coil with respect to the primary coil and has the capability to transfer power continuously to the moving load at every position.

Optimal U/f-control of high speed permanent magnet motors

Abstract: High speed motors are used nowadays more and more in many applications such as turbo blowers and compressors, microturbine gas generators, machine tools and down-hole oilpumps. Benefits of high speed motor drives are the reduced size and the increased efficiency compared to the conventional technology consisting typically of a motor and a gearbox. High speed motors used are mainly permanent magnet synchronous motors (PM-motors) and induction motors. PM-motors are more widely used due to the better power factor and efficiency although the control of PM-motors is more difficult, for example, due to the insufficient natural damping of motor dynamics. Furthermore the carbon fiber sleeve, usually used around the rotor magnets, prevents the heat conducting away from the rotor surface. This, together with a poor control, easily results in rotor overheating problems. Special control methods and pulse width modulation are usually needed to overcome this kind of problems. In this presentation, special control issues are discussed for the optimal U/f-control of high speed PM-motors.

A Single Phase Multilevel Hybrid Power Filter for Electrified Railway Applications

Abstract: To improve the power quality of traction power system, a current control method implemented on a multilevel hybrid power filter (MHPF) to compensate harmonics and reactive power is presented. Regarding the traction substation as a compensating object, the power quality of a traction substation can be improved integrally. The hybrid filter consists of a passive filter and a low-rated multilevel power converter. The passive filter works not only as a harmonic filter tuned at the 3 rd harmonic frequency, but also as a switching-ripple filters. The multilevel active power quality compensator uses source voltage reference to determine the compensating currents for single phase traction power systems. The rating of the switching devices for the active filter decreases with the use a multi-level inverter topology. Simulation results confirm the validity of the system and show that the adopted current control method is able to compensate reactive power and harmonics in the traction substation single phase 25 kV systems

Voltage source Inverter Based three-phase shunt active Power Filter: Topology, Modeling and Control Strategies

Abstract: Shunt active power filters (shunt APFs) represent the most important and most widely used filters in industrial purposes, this is due not only to the fact that they eliminate the harmonic current with a neglected amount of active fundamental current supplied to compensate system losses, but also they are suitable for a wide range of power ratings. Modern power electronic devices such as IGBTs allowed to configure non- harmonic generating shunt APFs, this paper focuses on this type of configuration namely the voltage source inverter based three- phase shunt active power filters aiming to present an overview on the mater.

Converting PLC instruction sequence into logic circuit: A preliminary study

Abstract: By implementing a control program with hard-wired logic using reconfigurable devices (e.g., FPGA), a flexible and highly responsive system can be realized. This new system also contributes to securing intellectual property, while reducing implementation space and cost. This study outlines a converter that translates PLC instruction sequence into logic description. A design framework is also described, which integrates control logic and peripheral functions on an FPGA chip. A productive ladder program was examined with Mitsubishi Electric FX2N PLC and Altera APEX20KE FPGA, and the derived logic designs were shown to fit into an actual FPGA chip. A straightforward Sequential design was estimated to be 79 times faster than PLC, while a performance-oriented Flat design was estimated to be 43 times faster than Sequential design (i.e., 3397 times faster than PLC).

Human-Machine Interface Based on Electro-Biological Signals for Mobile Vehicles

Abstract: In this paper, a system to allow the communication between a human being and a robot, through a Human-Machine Interface (HMI), is proposed. Such HMI makes possible to use electro-biological signals, such as ElectroMyoGram (EMG), ElectroOculoGram (EOG) and ElectroEncephaloGram (EEG) to control devices like an autonomous wheelchair. An electronic board containing an environmental map has also been developed. Thus, the user selects a cell in the map, through some electro-biological signal, which is understood by the system as the place the mobile vehicle should reach. A control system to guide the robot to seek for this goal is also presented, including experimental results.

Input filter design for SVM Dual-Bridge Matrix Converters

Abstract: This paper gives a simple procedure to size the input filter parameters for DBMC. The proposed methodology performs a reasonable THD of the line current as well as a compromise between the input power factor and the THD of the input filter capacitor voltage. On the other side, the input filter performances are evaluated in detail when the converter is controlled by a SVM scheme. Finally, future trends are proposed to overcome the observed drawbacks by using advanced control strategies.

Parasitic Inductance Effects on the Switching Loss Measurement of Power Semiconductor Devices

Abstract: This paper gives the detailed analysis of the parasitic inductance effects on the switching loss measurement of power semiconductor devices, especially IGBTs. Base on the circuit operation analysis and measurement of IGBT characteristics, it's shown that the larger parasitic loop inductance will result in more turn-off losses but less turn-on losses, while the emitter inductance of the IGBT also has a significant effect on the gate drive circuit because it's included not only in the main power circuit but also in the gate drive circuit. It's proved that the emitter inductance slows down the turn-on and turn-off procedure thus increases the turn-on and turn-off switching power losses.

Induction Motor Fault Detection by using Wavelet decomposition on dq0 components

Abstract: Early detection of interturn shorts during motor operation would eliminate consequential damage to adjacent coils and the stator core, then reducing repair costs and motor outage time. In addition to the benefits gained from early detection of turn insulation breakdown, significant advantages would accrue by locating the faulted coil within the stator winding. Fault location would not only increase the speed of the repair, but would also permit more optimal scheduling of the repair outage. Motor Current Signature Analysis (MCSA) method is widely used as a diagnose tool for industrial applications. On the other hand, Park's transform is the most popular transformation used in vector control algorithms. By analyzing the current spectra of dq0 Park components with MCSA method it is possible to improve earlier fault detection. Moreover, using Wavelet transform as signal analysis method it is possible to reduce signal noise effects. Experimental results clearly corroborate the main aim of the paper.