Prof. Dr. Joachim Holtz
Editor-in-Chief
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Prof. Dr. Joachim Holtz |
Power Electronics
- Two-Phase Modulation Technique for Three-Level Inverter Fed AC Drives
by Sandor Halasz, Bin T. Huu, Alexej Zacharov
Abstract - Two-phase dipolar and unipolar modulation techniques for three-level three-phase inverters are suggested and compared with conventional three-phase PWM techniques. Two-phase PWMs with 60° (0° and +- 30° shift) and 120° cycles are investigated from the point of view of harmonic losses, motor voltage spectra and torque pulsations. It is shown that two-phase dipolar PWMs have no advantages in comparison with three-phase PWMs while two-phase unipolar PWMs - in contrast with three-phase PWMs - considerably decrease the motor harmonic losses and torque pulsations in the whole motor voltage region. At the same time the inverter neutral point control requires reversing to three-phase PWM technique for the duration of the control.
- A New Passive 30-Step Current Shaper for 3-Phase Rectification
by Chern-Lin Chen, Guo-Kiang Horng
Abstract - A new passive 28-step current shaper for 3-phase rectification is proposed in this paper. With a phase-shifting transformer on the ac side and six interphase transformers on the dc side, per phase input current can be shaped into a 28-step sinusoidal waveform. The total harmonic distortion of ac input currents obtained is 6.54%, lower than one half of that in a conventional 12-pulse converter. The transformer VA rating is also lowered down to one-fifth of that in a 12-pulse converter. A 2kW experiment is performed to verify the proposed circuit.
- A Neural Network Based Controller for the Cost-Effective Operation of a Hybrid Compensator for Non-Active Power
by R. W. Pretorius, I. S. Shaw, J. Daan van Wyk
Abstract - The need to eliminate distortion from power networks has led to the development of various compensator topologies. The increasing cost of electrical energy requires the choice of the most cost-effective compensator operation. An investigation of a neural network based controller that chooses the most cost-effective compensator mode of operation on the basis of a continuous analysis of load conditions, and the operational losses of the elements in the compensator structure is reported. The modelling of operational losses of each subtopology and the required control strategy are discussed. The results show that the operational loss savings due to the neural network-controlled hybrid compensator were 30% to 70% as compared to the conventionally controlled hybrid compensator, while also conforming to other control strategy requirements.
- A New Hybrid C-Dump and Buck-Fronted Converter for Switched Reluctance Motors
by K. J. Tseng, S. Cao, J. Wang
Abstract - This paper presents an experimentally verified single-pulse-operation SRM converter topology based on the basic buck-fronted topology and the modified C-dump topology. Using only (n+1) power switches, this topology is able to achieve full single-pulse-operation, thereby reducing switching losses and acoustic noise. It also achieves a greater de-magnetizing voltage compared to the basic buck-fronted topology, without having to increase the DC source voltage. The converter is more robust as its dump capacitor stops being charged if the chopper switch fails. The principle of operation, modes of operation, transient simulation results and experimental results are presented.
- New Control Scheme for Class DE Inverter by Varying Driving Signals
by Hiroo Sekiya, Mitsuhiro Matsuo, Hiriotaki Koizumi, Shinsaku Mori, Iwao Sasase
Abstract - A new control scheme of class DE inverter is presented. This methodgenerates the output voltage and power by varying driving signalswhich turn switches on and off. The advantages of the proposed scheme are the improvement of the power conversion efficiency for low output voltage, the operation at fixed operatingfrequency, unneccessity of enlargement of the circuit scale, and suitability for controlling the wide output range. An exact analysis and circuit experiments are carried out. It is shown that the experimental results are very similar to the theoretical predictions qualitatively. Measured efficiency is over 93% with 1.0 MHz, 1.8 W output.
- Lossless Current Sensing in Low Voltage, High Current DC/DC Modular Supplies
by Enrico Dallago, Marco Passoni, Gabriele Sassone
Abstract - New data processing ICs require low-voltage high-current supplies together with high reliability and efficiency. The use of a modular power supply would be the ideal solution but it requires detecting the current in each module and resistive shunts are usually used. In this paper a new lossless current sensing circuit is presented. This lossless current transducer is obtained by applying the technique used to compensate the parasitic inductance in resistive shunts to the filter inductor of the DC/DC power supply. The causes that can influence transducer response are investigated. The current sensing was implemented in a modular DC/DC power supply and experimental results are reported.
- Development of a Distributive Control Scheme for Fluorescent Lighting based on LonWorks Technology
by J. Marcos Alonso, J. Ribas, J. J. Del Coz, A. J. Calleja, E. Corrominas, M. Rico-Secades
Abstract - In this paper a new distributive control system for indoor fluorescent lighting based on LonWorks technology is presented. The system features the following elements: microproces-sor-controlled fluorescent lamp electronic ballast, communication system using the power line as communication media and control software for Windows 95 environment. The electronic ballast has been especially designed to be operated under the proposed distributive control system. Thus, it features high input power factor, high frequency lamp supply, lamp power regulation against line voltage variations, dimming capability and lamp failure detection. With this scheme a low cost distributive control system for lighting applications has been achieved, allowing energy and maintenance saving and reliability increase of the fluorescent lighting systems.
- Single-Switch Electronic Ballast with Continous Input Current Charge Pump Power Factor Correction
by Chang-Chiarn Lin, Chern-Lin Chen
Abstract - This paper presents a single-switch electronic ballast with continuous input current charge pump power factor correction. The ballast circuit is composed of a series/parallel inverter, a charge pump power factor corrector and a dimming controller. The characteristics and design considerations of this ballast are discussed in this paper. Dimming control is achieved by varying the switching frequency. The frequency modulation scheme is used to reduce the low-frequency output current ripple. A prototype of 36WT8 fluorescent lamp ballast has been implemented and tested. Experimental results verify the analytical derivations.
- A Novel Energy Recovery Sustaining Driver for Plasma Display Panel
by Chen-Chang Liu, Chern-Lin Chen, Kelvin Lee
Abstract - A novel energy recovery driver is proposed to drive a plasma display panel (PDP) in the sustaining operation. The proposed circuit uses the parallel resonance between the inductor and the intrinsic capacitance of PDP to mainly recover the energy lost by the capacitive displacement current of PDP. The parasitic resonance caused by the parasitic inductance and the stray capacitance is prevented greatly. A 34-inch AC PDP equipped with the proposed driving circuit, operated at 100 kHz, is investigated. In addition, some prior arts are shown in this paper for comparison, and their power consumption of driving the same 34-inch panel is measured. The experimental results show that the proposed driver has a low cost structure and better performance than the prior ones.
- Comparison of Simulation Algorithms for Accelerated Determination of Periodic Steady State of Switched Networks
by Duwang Li, Richard Tymerski
Abstract - This paper presents a comparison of the following algorithms for accelerated determination of periodic steady state of switched networks: Newton's method with analytically determined Jacobian, Newton's method with numerically determined Jacobian, Newton's method with Broyden updates of an initial numerically determined Jacobian, Newton's method with a globally convergent strategy (and numerical Jacobian), Bukowski's method and Skelboe's method. Each algorithm is incorporated into a very accurate power electronics' simulator (PECS) at source-code level and compared on a common basis. The results on several switching converters suggest the analytical Newton's method to be the most accurate and fastest. When analytical derivatives are not available, both Broyden's and Skelboe's methods are competitive.
Drive Control
- Sensorless Sliding Mode Control of Induction Motor
by Zhang Yan, Changxi Jn, Vadim I. Utkin
Abstract - This paper develops the ideas of speed and flux sensorless sliding mode control for induction motor.A sliding mode observer/controller is proposed in this paper. The convergence of the nonlinear time-varying observer along with the asymptotic stability of the controller is analyzed. PWM implementation using sliding mode concepts is also discussed. The major attention is paid to torque control, then the developed approach is utilized for speed control. Computer simulations and experiments have been carried out to test the proposed estimation and control algorithm. The experimental results demonstrated high efficiency of the proposed estimation and control method.
- A High-Precision Positioning Servo-Controller based on Phase/Frequency Decting Technique of Two-Phase Type PLL
by Takashi Emura, Lei Wang, Masashi Yamanaka, Hisashi Nakamura
Abstract - This paper presents a new method proposed for high-precision positioning servomechanisms. The servo-controller uses two-phase type PLL (Phase-Locked Loop) to detect position tracking error and speed fluctuation with high resolution. The two-phase type PLL has wide frequency range and excellent noise-suppression performance. The proposed method was applied to a high-productivity NC (Numerically Controlled) gear grinding machine. This NC machine uses a servo-spindle of 20 kW and 10,000 r/min, and requires a high positioning resolution. Based on the two-phase type PLL, a servo-controlled was developed for the servo-spindle and achieved resolution is up to 5.625 arc second even at the high rotary velocity of 10,000 rpm. Experiments of gear grinding were carried out and the results demonstrated the performance of the developed controller.
- A Spice Model for a Novel Brushless Adjustable-Speed Drive
by Michael A. Inerfield, Steven L. Garverick, Wyatt S. Newman, Yuandao Zhang
Abstract - A SPICE circuit model was developed to accurately simulate the i-v characteristics of a brushless AC motor commutated by semiconductor switches. The model is based on Fourier curve fits to measured mutual inductance interactions between all combinations of field and armature windings, as well as coil resistance and inductance. The model is able to accurately predict current and voltage characteristics, both statically, and dynamically when interfaced with a commutation model. The model has been demonstrated to agree with electrical tests of an inverted motor on a large time scale. It has also given reliable predictions of small time-scale details, where it is desirable to predict power MOSFET switch behavior after a command to open or close. Data were collected and analyzed for simulations of the motor model combined with a commutation model containing MOSFET switches. Metrics were compared to data collected from an inverted brushless motor with good agreement.
- Microcomputer Implementation of Optimal Algorithms for Closed-Loop Control of a Hybrid Stepper Motor Drives
by Petar Crnosija, Stipe Ajdukovic, Branislav Kuzmanovic
Abstract - Optimal algorithms for closed-loop control of hybrid stepper motor drive and their microprocessor implementation are discussed here. The torque characteristics and the optimal control angle of hybrid stepper motor drives with added series resistance and reluctant stepper motor drives have been described in detail in the literature. The specific contribution of the present paper to this field of research consists of the analysis of the torque characteristics and the optimal control angle of hybrid stepper motor drives with a chopper amplifier and current controller. Analytical expressions for the average torque and the optimal control angle of a two-phase hybrid stepper motor with chopper amplifier and current controller have been developed. An actual hybrid stepper motor drive and the microcontroller-based implementation of the suboptimal and exact optimal control algorithms have been described. The experimental results obtained by positioning a two-phase hybrid stepper motor drive with chopper amplifier, phase current controller, and incremental encoder suggested that the derived optimal control algorithm provided maximum acceleration and minimum positioning time of the hybrid stepper motor drive.
Signal Processing
- Real Time and an In-Process Measuring System for the Grinding Process Cylindrical Workpieces using Kalman Filtering
by Man Hyung Lee, Jong Il Bae, Kang Sup Yoon, Fumio Harashima
Abstract - This paper introduces an in-process measurement system that does not pause during the machining processes. The system could result in enhanced productivity and quality control in manufacturing processes that use a surface grinding spindle. For the gauging sensor of the measurement system, we propose an eddy current sensor because it is a noncontact type, which uses an eddy current induced when a metallic material is placed in a high frequency electromagnetic field. Also, it is very insensitive to other kinds of interference such as cutting fluids, coolants, contact pressure, and wear at the contact point. For data analysis, the measurement system was modelled as a linearized discrete form, and the states with noises were estimated by an extended Kalman filter. Validation of this system was performed through a simulation and an experiment.
Emerging Technologies
- Optimization of Spare Capacity in Self-Healing Multicast ATM Network using Genetic Algorithm
by Sam Kwong, D. Lam
Abstract - The objective of this paper is to optimize the amount of Spare Capacity reserved for the Backup Virtual Paths (BVP) in multicast ATM Networks. In this paper, we will study the capacity and routing assignment problem arising in the design of self-healing networks using the Virtual Path (VP) concept. A major contribution of this work is to apply Genetic Algorithm (GA) to the backup path search process instead of the trivial exhaustive search method. Experimental results indicate that both approaches have very comparable results in finding the multicast backup paths. Further, it also indicated that using Genetic Algorithm approach has a number of advantages over the exhaustive search approach such as the computational requirement for Genetic Algorithm in finding good BVPs is small when compared to the exhaustive search method. A major drawback of our approach is that we cannot guarantee the finding of global optimum in real-time.
Letters to the Editor
- Feasibility of Contact and Non-Contact Material Handling using Traveling Waves and Transition Characteristics
by Paul I. Ro, Byoung-Gook Loh, Javier Santiago
Abstract - The feasibility of using traveling waves as a mechanism for industrial material handling is examined. A prototype was constructed to experimentally investigate the feasibility of the proposed method. Two kinds of transport method are investigated: frictional drive and acoustic levitation. Experimental transport speed characteristics are presented. The transition characteristics from acoustic levitation to frictional drive are also experimentally examined.
- A Neural Learning based Reflectance Model for 3-D Shape Reconstruction
by Siu-Yeung Cho, Tommy W. S. Chow
Abstract - In this paper, the limitation of the conventional Lambertian reflectance model is addressed and a new neural based reflectance model is proposed of which the physical parameters of the reflectivity under different lighting conditions are interpreted by the neural network behavior of the nonlinear input-output mapping. The idea of this method is to optimize a proper reflectance model by a neural learning algorithm and to recover the object surface by a simple SFS variational method with this neural based model. A unified computational scheme is proposed to yield the best SFS solution. This SFS technique has become more robust for most objects even when the lighting conditions are uncertainty.
- Adaptive Time Delay Controller
by A. B. Rad, W. L. Lo, K. M. Tsang
Abstract - A time delay controller is proposed in this communication. This controller possesses attractive properties such as requiring only one tuning parameter. Furthermore, it can be applied to higher-order systems as well as systems with dominant time delay. The basic structure is integrated with an on-line estimation algorithm to form an Adaptive Time Delay Controller (ATDC). An experimental study is included to demonstrate its performance and merits compared with two similar controllers.
