IEEE Transactions on Industrial Electronics

Volume 52, Number 4, August 2005 Access to the journal on IEEE XPLORE IE Transactions Home Page

Special Section Papers on Optomechatronics

52.4.1	H. Cho, M.Y. Kim, "Optomechatronic Technology: The Characteristics and Perspectives," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 932- 943, August 2005. Abstract Link Full Text Abstract: In recent years, optical technology has been incorporated into mechatronic systems at an accelerated rate, and as a result, a great number of machines/systems with smart optical components have been introduced. This integrated technology is termed “optomechatronics.” This paper introduces the fundamental concept, definition, and characteristics of the technology by analyzing the characteristics of a variety of practical optomechatronic systems. The introduction describes how optical and mechatronic components are physically coupled to each other to form optomechatronic integration. With this observation, we describe the nature and integration concept of the technology, from which we can derive the technology-driven fundamental functionalities in some detail. Based upon the knowledge on basic optomechatronic integration and functions, we analyze optomechatronic systems in general from the viewpoint of system configuration and design and, thus, the roles of optical technology in overall system performance being learned and the synergistic effects due to its fusion with mechatronics being understood.
52.4.2	W. Baetz, J. Braasch, W. Holzapfel, "Noise-Modulated Optomechatronic Distance-Measuring System," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 944- 952, August 2005. Abstract Link Full Text Abstract: A novel measuring system for optical distance sensing of solid targets is described. The system simply applies a noise-frequency-modulated laser diode for illuminating the target and an interferometer/photodetector device for coherent beam detection. This configuration is treated here as an optomechatronic correlator. The delay in travel time of the target beam in the interferometer yields a stochastically modulated electrical beat frequency in the photodetector output. Its mean frequency value is a measure for the target distance. Additionally to the required stochastic modulation of the injection current, the natural phase noise modulation of the laser diode also has to be taken into account. Theory delivers nonlinear measurement characteristics with strongly increased slope at the short-distance range. The experimental verification in a distance range up to 4 m shows a relative distance measurement error from$hbox10^-3$to$hbox10^-2(1sigma)$for an averaging time range from 10 to 1 s. The system is potentially qualified for approach sensing in mechatronic devices like tool machinery and robotics.
52.4.3	K.S. Moon, M. Levy, Y.K. Hong, H.K. Park, "Axial Displacement Measurement of a Single-Crystal Actuator Using Phase-Shift Interferometry," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 953- 959, August 2005. Abstract Link Full Text Abstract: Due to their superior piezoelectric coefficients, PZN-PT ($(1- x)$Pb(Zn$_1/3$Nb$_2/3$)O$_3- x$PbTiO$_3$) and PMN-PT [$(1- x)$Pb(Mg$_1/3$Nb$_2/3$)O$_3- x$PbTiO$_3$] are viewed as possible substitutes for conventional PZT in advanced piezodevices. This paper presents noncontact displacement measurements in small rectangular PZN-PT and PMN-PT crystal rods. We propose a new phase-shift-interferometry-based technique for static and dynamic axial displacement measurement. The measurement technique makes use of the fact that the sinusoidal intensity data from the same pixels in two interferograms with different phase shifts form an elliptic Lissajous curve. We can accurately estimate phase-shift steps by fitting the elliptic Lissajous curve by least squares. Actuator displacements are then calculated from the estimated phase-shift steps. In this paper, the proposed technique was integrated with a Mirau interferometeric microscope with a machine vision system. This optomechatronic measurement system was used to measure the piezoelectric coefficient$d_31$of$langle 001rangle$-poled PZN-PT and PMN-PT single crystals as well as hysteresis. Simulations and experiments demonstrate that the proposed technique is robust against the influence of intensity noise in interferograms.
52.4.4	Y. Yamada, M. Morizono, U. Umetani, T. Takahashi, "Highly Soft Viscoelastic Robot Skin With a Contact Object-Location-Sensing Capability," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 960- 968, August 2005. Abstract Link Full Text Abstract: This paper concerns the development of robot skin capable of accurately sensing the location of objects in area contact with the skin surface. There has been no report on tactile sensing which attained not only skin deformation detection but also contact object location sensing with high accuracy. In the category of optomechatronics technology, we apply optical fibers to transmit surface deformation information of soft skin for sensing the location of an object in contact with the soft skin accurately. In the paper, we illustrate the structure of the robot skin, and describe the principle of both detecting the position of the reflector chips and sensing the contact location of an object. The robot skin is characterized by the fact that the surface is low cost and easily replacable, and the sensing performance is robust against any electromagnetic disturbance. We then show experimental results for verifying the principles using a wedge-shaped object. For evaluating the sensing accuracy, comparisons are made: 1) between the location of a real convex of the object and that of the corresponding estimated polygon and 2) for the position of two vertices of the object when independent fitting and Lagrangian fitting methods are applied.
52.4.5	C.I. Nitu, B.S. Gramescu, C.D.P. Comeaga, A.O. Trufasu, "Optomechatronic System for Position Detection of a Mobile Mini-Robot," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 969- 973, August 2005. Abstract Link Full Text Abstract: This paper presents an optomechatronic system which can detect, by triangulation, the position of a light point source, fastened onto a robot part. The sensing system consists of two positioning modules for optical transducers, which automatically follow the direction of the light point source. The system control is accomplished by means of data acquisition boards and LabVIEW programming.
52.4.6	S. He, R. BenMrad, "Large-Stroke Microelectrostatic Actuators for Vertical Translation of Micromirrors Used in Adaptive Optics," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 974- 983, August 2005. Abstract Link Full Text Abstract: Two microelectrostatic actuators able to produce a repulsive force in the out-of-plane direction are presented in this paper. The electrostatic actuators use an asymmetric electric field surrounding the top and bottom surfaces of the moving fingers to produce a repulsive force. The displacement of translation micromirrors driven by these actuators is not limited by the “pull-in” effect and, therefore, can achieve a large stroke. In addition, the usage of a repulsive force leads to the elimination of the stiction problem. An analytical model relating the displacement of the first actuator to voltage applied is presented. The analytical model and numerical simulations show that a translation micromirror driven by the first actuator can achieve a stroke as large as 6$muhboxm$at a driving voltage of 50 V. The second actuator, suitable for fabrication using Multi-User-MEMS-Processes (MUMPs), is developed. A prototype translation micromirror driven by the second actuator achieved a vertical stroke of 2$muhboxm$, which is more than three times the stroke of conventional MUMPs translation micromirrors.
52.4.7	T. Oguchi, M. Hayase, T. Hatsuzawa, "Micromachined Display Device Using Sheet Waveguide and Multicantilevers Driven by Electrostatic Force," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 984- 991, August 2005. Abstract Link Full Text Abstract: A new structure for display devices is proposed and fabricated by the microelectromechanical systems process. The device is based on physical contact and evanescent coupling between a sheet waveguide and electrostatically driven multicantilevers. When incident light is propagated into the waveguide and the cantilevers contact the waveguide by applying a dc voltage, the switched light is emitted from the side edges of the contacted multicantilevers, resulting in a display device. The device contributes to the expansion of the switching area, the removal of unnecessary scattered light, and high contrast due to the simple fabrication and structure with corner spacers for the optical separation between the cantilevers and the waveguide. Based on the experimental results with the device, a contrast of 0.9 is obtained at 170 V, and a stable drive is realized up to 1 kHz. Therefore, the device can be expected to be used for display devices by the fabrication of an array structure.
52.4.8	Y. Katagiri, H. Takesue, E. Hashimoto, "Wavelength-Scanning Optical Bandpass Filters Based on Optomechatronics for Optical-Frequency Sweepers," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 992- 1004, August 2005. Abstract Link Full Text Abstract: We propose and demonstrate a method for improving optical-frequency sweepers that uses a disk-shaped optical bandpass filter operated under the synchro-scan mode. We optimize the filter layer structure to achieve high linearity in optical-frequency tuning with the rotation angle of the disk, while maintaining a constant band-inhibition performance. We introduce an optical system that narrows the bandwidth by using an optimized beam coupler and improves the filtering performance by using a multiple-path method. The optimized filter enables a stable linear optical-frequency sweep when it is used with a motor stabilized by phase locking. The improved optical frequency sweepers can extend the sweep range to above 2 THz, while suppressing the accumulation of spontaneous emission noise.
52.4.9	E.T. Enikov, L.L. Minkov, S. Clark, "Microassembly Experiments With Transparent Electrostatic Gripper Under Optical and Vision-Based Control," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1005- 1012, August 2005. Abstract Link Full Text Abstract: This paper describes the assembly experiments conducted with a novel miniature assembly cell for microelectromechanical systems. The cell utilizes a novel transparent electrostatic gripper and uses several disparate sensing modalities for position control: computer vision for part alignment with respect to the gripper, a fiber-coupled laser, and a position-sensitive detector for part to assembly alignment. The assembly experiments performed indicate that the gripping force and stage positioning accuracy of the gripper are sufficient for insertion of micromachined parts into slots etched in silicon substrates. Details of the cell operation, the control algorithm used, and their limitations are also provided. Potential applications of the developed assembly cell are assembly of miniature optical systems, integration of optoelectronics, such as laser diodes with CMOS, and epitaxial lift-off of thin films used in optoelectronic devices.
52.4.10	G. Yang, J.A. Gaines, B.J. Nelson, "Optomechatronic Design of Microassembly Systems for Manufacturing Hybrid Microsystems," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1013- 1023, August 2005. Abstract Link Full Text Abstract: Microassembly systems are a class of representative optomechatronic systems that play a critical role in the fabrication, packaging, and interconnection of hybrid microsystems such as hybrid microelectromechanical systems. Optomechatronic integration is essential to the development of microassembly systems due to the basic importance of microscope optics to microassembly. In this paper, the role of microscope optics in microassembly systems is analyzed. The general architecture of microassembly systems is introduced. Unique properties of microscale optomechatronics that differ from macroscale optomechatronics are summarized. These fundamental differences motivate the definition and discussion of microoptomechatronics. Major methodology issues in optomechatronic design of microassembly systems are introduced using examples. A wavelet-based microscopic image segmentation technique is presented to demonstrate the strength of using the unique properties of microoptomechatronics in microscopic image information processing.
52.4.11	L. Deng, F. Febabi-Sharifi, W.J. Wilson, "Hybrid Motion Control and Planning Strategies for Visual Servoing," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1024- 1040, August 2005. Abstract Link Full Text Abstract: This paper presents two hybrid strategies for robot visual servoing. Two specific image constraints, the image singularities and image local minima, are considered in both strategies. The hybrid motion control strategy consists of a local switching control between the image-based and position-based visual servoing for direct avoidance of image singularities and image local minima. The hybrid motion planning strategy consists of an artificial potential field-based global hybrid trajectory planner, where a complete set of Cartesian, image, and robot joint constraints under a complex visual servoing scenario are considered. In this strategy, the image singularities are resolved using the damped-least-square-based joint trajectory planning, while the image local minima are evaluated only along the planned image trajectories and automatically avoided in the image-based trajectory tracking. Two global planning methods are considered. In the first method, the end-effector trajectory is directly planned with respect to the stationary target object frame, which provides a much shorter translational path compared with the local planning method. In the second method, the target trajectory is planned with respect to the current end-effector frame, which minimizes the chances of image trajectories leaving the camera field of view. Simulation and experimental results are given to demonstrate the efficiency of the two hybrid strategies.
52.4.12	T. Takeguchi, S. Kaneko, "Using Depth Aspect Images for Robust and Efficient Search of Multiple Objects in Optomechatronic Sensing," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1041- 1049, August 2005. Abstract Link Full Text Abstract: A system is proposed for robust and efficient search for solid objects in a cluttered depth scene. Since the system is designed for obtaining robustness in real industry applications, it utilizes only depth information without color or texture on the object surfaces. The search is based on image matching of our novel surface representation called depth aspect image (DAI). The representation defined as a basic cue for the search is a two-dimensional orthographic image of local depth distribution and it is created through voxel framing, which gives effective references for definition of various aspects without any prominent features on the surfaces such as vertices or edges. For local coordinates of DAIs, the aspect coordinate frame is defined by 3-tuples of voxels and five constraint conditions on the 3-tuples can be formalized for the efficient selection. These can contribute to a reduction of the number of possible voxel sets. A robust statistical estimator called least quantile of residuals is furthermore introduced for robust matching even in the presence of occlusion and/or lack of data. The estimator can be utilized for both depth matching and model verification. Since the proposed system is following a model-based approach with possible views of local depth distributions, the computation cost for matching has to be reduced by introducing random sampling and an effective hashing. The sufficient number of trial samplings is derived through investigation and modeling of voxel arrangement. Experiments with real scenes show the effectiveness of the proposed method.
52.4.13	Y.-S. Kim, S.-J. Lee, N.-C. Park, Y.-P. Park, "Design of a Superparaboloidal Solid Immersion Mirror for Optomechatronic Near-Field Recording," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1050- 1055, August 2005. Abstract Link Full Text Abstract: We designed a superparaboloidal solid immersion mirror (SP-SIM) using a tilted parabolic mirror that applied total internal reflection to an optical flying head for near-field recording. As an SP-SIM does not need an objective lens or folding mirror, the height and weight of the optical flying head can be reduced. Using theoretical ray tracing, we found the optimal parameters for rotational symmetric beam intensity on a high-numerical-aperture (NA) focus. The effective NA of the SP-SIM was 1.32 for both the sagittal and meridional focuses. A 408-nm laser source and high refractive index material, NbFD13, was used for the simulation. The minimum spot sizes at full width 1/e$^2$intensity were 237 and 232 nm in the sagittal and meridional directions, respectively, at normal incidence. The size of the beam spot was kept nearly uniform within a maximum 5% deviation as the field angle changed within$pmhbox0.15^circ$. The SP-SIM measured 0.83 mm$,times,$0.95 mm$,times,$0.27 mm$(hboxWtimes hboxLtimes hboxH)$and weighed ca. 0.6 mg.
52.4.14	Kyung-Soo Kim, "Analysis of optical data storage systems - tracking performance with eccentricity," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1056- 1062, August 2005. Abstract Link Full Text Abstract: The tracking control performance of optical data storage systems is analyzed in the presence of the disc eccentricity. The eccentricity is the maximum deviation from the geometric center of the circular tracks and the rotating center of the disc, which is inevitable in practice. This is mainly caused by the inaccuracy of the tracking forming devices. In the paper, tracking control performance is discussed in terms of pull-in capability and steady track-following ability. Firstly, it will be explicitly shown that the pull-in capability will degrade in proportion to the multiplication of the eccentricity and rotational frequency. This analysis provides a guide for tracking controller design with reliable pull-in actions. Secondly, in order to improve the steady track-following performance, a feedforward compensation method is introduced, which is simple enough to be implemented in practice. Furthermore, an interesting connection to the disturbance observer approach in the time domain is examined.
52.4.15	S.J. Hong, G.S. Oct, "Neural-Network-Based Sensor Fusion of Optical Emission and Mass Spectroscopy Data for Real-Time Fault Detection in Reactive Ion Etching," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1063- 1072, August 2005. Abstract Link Full Text Abstract: To achieve timely and accurate fault detection in reactive ion etching, neural networks (NNs) have been applied for the fusion of data generated by two in-situ sensors: optical emission spectroscopy (OES) and residual gas analysis (RGA). While etching is performed, OES and RGA data are simultaneously collected in real time. Several pre-determined, statistically significant wavelengths (for OES data) and atomic masses (for RGA signals) are monitored. These data are subsequently used for training NN-based time series models of process behavior. Such models, referred to herein as time series NNs (TSNNs), are realized using multilayered perceptron NNs. Results indicate that the TSNNs not only predict process parameters of interest, but also efficiently perform as sensor fusion of the in-situ sensor data.
52.4.16	C.-S. Cho, B.-M. Chung, M.-J. Park, "Development of Real-Time Vision-Based Fabric Inspection System," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1073- 1079, August 2005. Abstract Link Full Text Abstract: Quality inspection of textile fabric products is an important problem for fabric manufacturers. This paper presents an automatic vision-based system for the quality control of web textile fabrics. Typical web material is 1–3 m wide and is driven with speeds ranging from 20 to 200 m/min. At present, the quality inspection process is manually performed by experts. However, they cannot detect more than 60% of the overall defects for the fabric if it is moving faster than 30 m/min. To increase the quality and homogeneity of fabrics, an automated visual inspection system is needed for better productivity. Currently, the existing inspection systems are too expensive for small companies. In this paper, a PC-based real-time inspection system is proposed with benefits of low cost and high detection rate. The proposed algorithm showed good results for several types of fabric defects. Power Electronics
52.4.17	J. Rodriguez, P.W. Hammond, J. Pontt, R. Musalem, P. Lezana, M.J. Escobar, "Operation of a Medium-Voltage Drive Under Faulty Conditions," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1080- 1085, August 2005. Abstract Link Full Text Abstract: This paper presents a method for operating cascaded multilevel inverters when one or more power cells are damaged. The method is based on the use of additional switches in the power circuit to bypass the faulty cell. To control the cells, the angle of phase shifting in the carrier signals is modified according to the number of operating cells, to minimize the load voltage distortion, when the inverter operates in failure mode. The reference signals of the pulsewidth-modulation modulators are also modified to increase the output voltage. Simulation and experimental results show the effectiveness of this method, which significantly increases the reliability of the drive.
52.4.18	R.P. Burgos, E.P. Wiechmann, "Extended Voltage Swell Ride-Through Capability for PWM Voltage-Source Rectifiers," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1086- 1098, August 2005. Abstract Link Full Text Abstract: Voltage swells are one of the most harmful disturbances present in industrial power systems, being capable of severely damaging, breaking, or tripping converters. In the case of pulsewidth-modulation voltage-source rectifiers (PWM-VSRs), swells first saturate their control system and then force them into six-pulse operation if no precautions are taken. This paper presents an extended ride-through strategy enabling these converters to deal and cope with swells of up to 1.8 p.u. (IEEE Std. 1159 swell definition). The proposed strategy first fully exploits the dc-link voltage capacity by dynamically entering the overmodulation region, and secondly by drawing inductive current in case the former action does not suffice. Dynamic overmodulation makes possible the straight ride-through of 15% and 42% three-phase and single-phase swells, whereas the modulation index supervisor/control loop drawing inductive current enables the ride-through for greater magnitude disturbances, all the while avoiding saturation of the converter control system. This is realized using decision-making space vector modulation, and a control system built over a nonlinear control law directly obtained from the converter complex state variable model. In this way, linear and decoupled$d$–$q$axes dynamics are attained, ensuring a constant dynamic response throughout the whole operating range. Finally, experimental results from a TMS320C32 digital-signal-processor-based 5-kVA laboratory prototype subjected to typical industry single- and three-phase swells ranging from 5% to 50% are presented. These confirm the predicted performance and feasibility of the proposed voltage swell ride-through strategy for PWM-VSRs.
52.4.19	C.-M. Wang, "A Novel Single-Stage Series-Resonant Buck–Boost Inverter," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1099- 1108, August 2005. Abstract Link Full Text Abstract: A novel single-stage series-resonant buck–boost inverter (SRBBI) is proposed in this paper. The main attribute of the novel inverter topology is the fact that it generates an ac output voltage larger or lower than the dc input one, depending on the instantaneous duty cycle. This property is not found in the classical voltage-source inverter, which produces an ac output instantaneous voltage which always lower than the dc input voltage. The state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the new single-stage SRBBI. The principle of operation, theoretical analysis, and experimental results of the proposed inverter, rated 500 W and operating at 40 kHz, are provided in this paper to verify the performance of the SRBBI.
52.4.20	A.K.S. Bhat, R. Venkatraman, "A Soft-Switched Full-Bridge Single-Stage AC-to-DC Converter With Low-Line-Current Harmonic Distortion," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1109- 1116, August 2005. Abstract Link Full Text Abstract: A single-phase high-frequency transformer-isolated soft-switching single-stage ac-to-dc converter with low-line-current distortion is presented. The circuit configuration is obtained by integrating two discontinuous current mode (DCM) boost converters with a DCM full-bridge buck converter. The zero-voltage switching for the top switches is achieved automatically, whereas bottom switches are aided by zero-voltage transition circuits. The output voltage is regulated by duty-cycle control at constant switching frequency. The intervals of operation and steady-state analysis are presented. A systematic design procedure is presented with a 1-kW converter design example. PSPICE simulation and experimental results obtained from a 1-kW laboratory prototype are presented for a wide variation in line and load conditions.
52.4.21	C.-M. Wang, "A New Family of Zero-Current-Switching (ZCS) PWM Converters," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1117- 1125, August 2005. Abstract Link Full Text Abstract: A new family of zero-current-switching (ZCS) pulsewidth-modulated (PWM) converters which uses a new ZCS-PWM switch cell is presented in this paper. The main switch and auxiliary switch operate at ZCS turn-on and turn-off, and all the passive semiconductor devices in the ZCS-PWM converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. Besides operating at constant frequency and with reduced commutation losses, these new converters have no additional current stress in comparison to the hard-switching converter counterpart. The new family of ZCS-PWM converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs). The PWM switch model and state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the system. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM boost converter, rated 1 kW and operating at 30 kHz, are provided in this paper to verify the performance of this new family of converters.
52.4.22	J.M. Guerrero, L. GarciadeVicuna, J. Matas, M. Castilla, J. Miret, "Output Impedance Design of Parallel-Connected UPS Inverters With Wireless Load-Sharing Control," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1126- 1135, August 2005. Abstract Link Full Text Abstract: This paper deals with the design of the output impedance of uninterruptible power system (UPS) inverters with parallel-connection capability. In order to avoid the need for any communication among modules, the power-sharing control loops are based on the$P/Q$droop method. Since in these systems the power-sharing accuracy is highly sensitive to the inverters output impedance, novel control loops to achieve both stable output impedance and proper power balance are proposed. In this sense, a novel wireless controller is designed by using three nested loops: 1) the inner loop is performed by using feedback linearization control techniques, providing a good quality output voltage waveform; 2) the intermediate loop enforces the output impedance of the inverter, achieving good harmonic power sharing while maintaining low output voltage total harmonic distortion; and 3) the outer loop calculates the output active and reactive powers and adjusts the output impedance value and the output voltage frequency during the load transients, obtaining excellent power sharing without deviations in either the frequency or the amplitude of the output voltage. Simulation and experimental results are reported from a parallel-connected UPS system sharing linear and nonlinear loads.
52.4.23	L. Asiminoaei, R. Teodorescu, F. Blaabjerg, U. Borup, "Implementation and Test of an Online Embedded Grid Impedance Estimation Technique for PV Inverters," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1136- 1144, August 2005. Abstract Link Full Text Abstract: New and stronger power quality requirements are issued due to the increased amount of photovoltaic (PV) installations. In this paper different methods are used for continuous grid monitoring in PV inverters. By injecting a noncharacteristic harmonic current and measuring the grid voltage response it is possible to evaluate the grid impedance directly by the PV inverter, providing a fast and low-cost implementation. This principle theoretically provides an accurate result of the grid impedance but when using it in the context of PV integration, different implementation issues strongly affect the quality of the results. This paper also presents a new impedance estimation method including typical implementation problems encountered, and it also presents adopted solutions for online grid impedance measurement. Practical tests on an existing PV inverter validate the chosen solution.
52.4.24	N. Kasa, T. Iida, L. Chen, "Flyback Inverter Controlled by Sensorless Current MPPT for Photovoltaic Power System," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1145- 1152, August 2005. Abstract Link Full Text Abstract: This paper presents a flyback inverter controlled by sensorless current maximum power point tracking (MPPT) for a small photovoltaic (PV) power system. Although the proposed system has small output power such as 300 W, a few sets of small PV power systems can be easily connected in parallel to yield higher output power. When a PV power system is constructed with a number of small power systems, the total system cost will increase and will be a matter of concern. To overcome this difficulty, this paper proposes a PV system that uses no expensive dc current sensor but utilizes the method of estimating the PV current from the PV voltage. The paper shows that the application of this novel sensorless current flyback inverter to an MPPT-operated PV system exhibits satisfactory MPPT performance similar to the one exhibited by the system with a dc current sensor as well. This paper also deals with the design method and the operation of the unique flyback inverter with center-tapped secondary winding. Drive Control
52.4.25	C. Cavallaro, A.O. DiTommaso, R. Miceli, A. Raciti, G.R. Galluzzo, M. Trapanese, "Efficiency Enhancement of Permanent-Magnet Synchronous Motor Drives by Online Loss Minimization Approaches," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1153- 1160, August 2005. Abstract Link Full Text Abstract: In this paper, a new loss minimization control algorithm for inverter-fed permanent-magnet synchronous motors (PMSMs), which allows for the reduction of the power losses of the electric drive without penalty on its dynamic performance, is analyzed, experimentally realized, and validated. In particular, after a brief recounting of two loss minimization control strategies, namely, the “search control” and the “loss-model control,” both a new modified dynamic model of the PMSM (which takes into account the iron losses) and an innovative “loss-model” control strategy are presented. Experimental tests on a specific PMSM drive employing the proposed loss minimization algorithm have been performed, aiming to validate the actual implementation. The main results of these tests confirm that the dynamic performance of the drive is maintained, and in small motors enhancement up to 3.5% of the efficiency can be reached in comparison with the PMSM drive equipped with a more traditional control strategy.
52.4.26	Y.X. Su, C.H. Zheng, D. Sun, B.Y. Duan, "A Simple Nonlinear Velocity Estimator for High-Performance Motion Control," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1161- 1169, August 2005. Abstract Link Full Text Abstract: Based on the fact that numerical integration can provide more stable and accurate results than numerical differentiation in the presence of noise, a constructive nonlinear velocity estimator (NVE) with simple computation is developed for high-quality instantaneous velocity estimation, based on the position measurement only. The attraction of the new velocity estimator is that it is very effective as well in the low-velocity ranges, it has high robustness against noise and design parameters, and it is easy to implement. Furthermore, the developed approach is model free. Both simulation and experimental tests have been run to verify its effectiveness and efficiency. The proposed new simple NVE has built a solid base for high-performance control of servo systems.
52.4.27	A. Derdiyok, "Speed-Sensorless Control of Induction Motor Using a Continuous Control Approach of Sliding-Mode and Flux Observer," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1170- 1176, August 2005. Abstract Link Full Text Abstract: This paper presents a continuous approach of sliding-mode current and flux observers for an induction machine. The proposed observer structure both decouples machine equations and makes them completely insensitive to rotor resistance variation. An estimation algorithm based on these observers is proposed to calculate speed and rotor resistance independently. In the proposed algorithm, the speed and rotor resistance are considered to be unknown constants, because the speed and rotor resistance change slowly compared to the electrical variables such as currents and fluxes. The simulation and experimental results demonstrate the good performance of the proposed observer and estimation algorithm and of the overall indirect-field-oriented-controlled system.
52.4.28	G.K. Singh, K. Nam, S.K. Lim, "A Simple Indirect Field-Oriented Control Scheme for Multiphase Induction Machine," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1177- 1184, August 2005. Abstract Link Full Text Abstract: Multiphase (more than three phases) drives possess several advantages over conventional three-phase drives, such as reducing the amplitude and increasing the frequency of torque pulsations, reducing the rotor harmonic currents, reducing the current per phase without increasing the voltage per phase, lowering the dc-link current harmonics, and higher reliability. By increasing the number of phases it is also possible to increase the power /torque per rms ampere for the same volume machine. This paper, therefore, presents a simple and straightforward approach to develop an indirect field-oriented control (FOC) scheme for a six-phase induction machine with an arbitrary displacement between the two three-phase winding sets. The two current-controlled pulsewidth-modulation three-phase voltage-source inverter independently feeds the two sets of three-phase stator windings. The scheme is based on simple two-axis ($d$–$q$) model of the six-phase induction machine, and can be easily extended to any number of phases, which are multiples of three. The unbalanced current sharing between the two three-phase stator-winding sets observed in earlier schemes is automatically eliminated, and the practical implementation of the scheme is simple. Necessary experimental and simulation results are presented to show the effectiveness of the proposed indirect FOC scheme. In the study, online analysis has been performed using$hboxC ^++$, while MATLAB /SIMULINK has been used to perform the offline analysis. Letters to the Editor
52.4.29	K. Sridharan, T.K. Priya, "The Design of a Hardware Accelerator for Real-Time Complete Visibility Graph Construction and Efficient FPGA Implementation," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1185- 1187, August 2005. Abstract Link Full Text Abstract: A valuable geometric structure in mobile robot path planning is the complete visibility graph. This letter proposes new parallel algorithms that can be mapped to reconfigurable hardware for construction of the complete visibility graph in an environment with: 1) multiple convex polygonal objects and 2) multiple nonconvex polygonal objects. Results of implementation in a Xilinx Virtex field-programmable gate array demonstrate that the proposed approach is area–time efficient: the design for an environment with roughly 60 vertices fits on one XCV3200E device and operates at close to 60 MHz.
52.4.30	H.-W. Kim, M.-J. Youn, K.-Y. Cho, "New Voltage Distortion Observer of PWM VSI for PMSM," IEEE Trans. on Industrial Electronics, vol. 52, no. 4, pp. 1188- 1192, August 2005. Abstract Link Full Text Abstract: A new online voltage distortion observation method against the motor parameter uncertainty of a permanent-magnet synchronous motor is proposed to estimate time-varying voltage distortion of a pulsewidth-modulation voltage-source inverter. This new estimation method is based on the model reference adaptive system.