SPECIAL SECTION ON ELECTRIC MACHINERY AND ADJUSTABLE-SPEED
MOTOR DRIVES—PART I
1. F. Rodriguez, A. Emadi, "A Novel Digital Control Technique for Brushless DC Motor Drives," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2365-2373, Aug 2007. Full Text Link
Abstract: Brushless dc (BLDC) motor drives are continually gaining popularity in motion control applications. Therefore, it is necessary to have a low cost, but effective BLDC motor speed/torque regulator. This paper introduces a novel concept for digital control of trapezoidal BLDC motors. The digital controller was implemented via two different methods, namely conduction-angle control and current-mode control. Motor operation is allowed only at two operating points or states. Alternating between the two operating points results in an average operating point that produces an average operating speed. The controller design equations are derived from Newton's second law. The novel controller is verified via computer simulations and an experimental demonstration is carried out with the rapid prototyping and real-time interface system dSPACE.
2. J.-L. Kuo, Z.-S. Chang, T.-S. Fang, "Design of Multisectional Driver and Field-Oriented Modeling of the Axial-Flux Linear Brushless Motor for Railway Transportations," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2374-2388, Aug 2007. Full Text Link
Abstract: A multisectional power driver design for the two-phase linear brushless motor will be proposed in this paper. The field-oriented modeling of the axial-flux linear brushless motor (AFLBM) will also be developed by using stationary and cosecant similarity transformation and singular value decomposition. Stationary and cosecant coordinate models will be derived based on the proposed approach. Decoupled relation and constant torque property will be obtained from the proposed models. Switching logic table for the linear motor operation is provided to drive the AFLBM properly. The switching-mode analysis for the power driver is also analyzed in detail. In order to increase the efficiency and the effectiveness of the electric motor applications, a multisectional driver circuit, which features the power driver with the so-called $N + 2$ structure, will be investigated and compared. Experimental results show that the proposed circuit design can achieve better performance with the higher efficiency. It is believed that the proposed driver circuit technique and system modeling can be very helpful to the control of railway transportations.
3. P. Beccue, S. Pekarek, "A Coupled Piezoelectric/Single-Hall-Sensor Position Observer for Permanent Magnet Synchronous Machines," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2389-2397, Aug 2007. Full Text Link
Abstract: In recent years, several control methods have been proposed to reduce the torque ripple produced by permanent magnet synchronous machines [sinusoidal and trapezoidal back electromotive force (EMF)]. In these approaches, a drive system is used to control current harmonics based upon measured machine parameters or measured torque ripple. In general, the methods presented have utilized high-precision position encoders and thus a common perception is that such encoders are required for successful mitigation. In this paper, a position observer is developed that is shown to be suitable for control-based torque ripple mitigation. Additional advantages of the observer are that it achieves excellent start-up performance, requires no knowledge of the machine parameters, and is applicable to machines with an arbitrary back EMF waveform and stator slot configuration.
4. Z. Xu, F. Rahman, "An Adaptive Sliding Stator Flux Observer for a Direct-Torque-Controlled IPM Synchronous Motor Drive," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2398-2406, Aug 2007. Full Text Link
Abstract: This paper focuses on performance improvements of the stator flux estimation for a direct-torque-controlled interior permanent magnet synchronous motor drive. In this paper, an adaptive sliding observer is presented to estimate the stator flux linkage based on the motor current model. The experimental results show that the proposed observer has been able to deliver more accurate estimation than an open-loop estimator both in the steady state and during transients. The observer has better dynamic behavior, disturbance resistance, and high-accuracy estimation ability. With the integrated flux observer, the drive system can operate at very low speed down to 10 r/min (0.33 Hz) with half full load.
5. S. Kaboli, M. R. Zolghadri, E. Vahdati-Khajeh, "A Fast Flux Search Controller for <>DTC<>-Based Induction Motor Drives," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2407-2416, Aug 2007. Full Text Link
Abstract: In this paper, a flux search controller is proposed to increase the efficiency of a direct torque-controlled induction motor in full load range. The value of the flux reference is determined through a minimization algorithm. The amplitude of stator current is used as the objective function since it is shown that samples of the stator current have better statistical properties than input power. In addition, the stator current has more sensitivity to the flux variation than input power. These two properties allow implementing an adaptive algorithm to determine the proper flux step without waste of time. The minimum allowable value of the flux step has been determined based on this process to prevent the divergence problem. This adaptive algorithm set a large flux step for transient state to speed up the convergence process and a small flux step for steady state to minimize the flux ripple. Simulation and experimental results presented in this paper confirm the fast dynamic of the proposed method.
6. T.-S. Hwang, J.-K. Seok, "Observer-Based Ripple Force Compensation for Linear Hybrid Stepping Motor Drives," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2417-2424, Aug 2007. Full Text Link
Abstract: This paper describes our research on a force ripple compensation and closed-loop position control scheme using linear hybrid stepping motors (LHSMs) with significant thrust vibrations. In order to estimate unobservable force ripple components, we propose the Jacobian linearization observer that guarantees the convergence of state estimates into true states. For the precise control of velocity and position, an input–output feedback linearization controller is derived from a nonlinear position-dependent model of the LHSM based on elaborate reluctance network analysis. In addition, we discuss the separation principle used to separate the observer design from the controller design. Common problems associated with the force ripple, such as the positioning error, mechanical stress, and acoustic noise, are efficiently handled using the proposed active damping control scheme. Experimental results show that the positioning accuracy is significantly improved through a closed-loop control while restraining the thrust ripple.
7. S. W. Zhao, N. C. Cheung, W.-C. Gan, J. M. Yang, J. F. Pan, "A Self-Tuning Regulator for the High-Precision Position Control of a Linear Switched Reluctance Motor," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2425-2434, Aug 2007. Full Text Link
Abstract: In the high-technology mass manufacturing industry, high-speed and high-precision motion is an indispensable element in the automated production machines. In recent years, there has been a growing tendency to employ direct drive permanent magnet linear synchronous motors in demanding motion applications. Although the overall performance is good, its implementation cost remains high. This is mostly due to the cost of the Neodymium–Boron magnets, the manufacturing of the magnetic rails, and the precision of the overall mechanics. In this paper, a much cheaper alternative is proposed-to use a low-cost linear switched reluctance motor (LSRM) and an adaptive control strategy to overcome the tolerances and difficult control characteristics inherent in the motor. The LSRM has simple and robust structure, and it does not contain any magnets. However, its force is solely drawn from the reluctance change between the coil and the steel plates. Variations on the behavior of these two elements due to different operating conditions will change the motion behavior of the motor. Also, to keep the overall cost low, the LSRM sets a marginal mechanical tolerance during its mass production. This leads to characteristic variations in the final product. Finally, since the LSRM is a direct drive motor, any variations on the motor characteristics will directly reflect on the control system and the motion output. In this paper, a self-tuning regulator (STR) is proposed to combat the difficulties and uncertain control behaviors of the LSRM. This paper first introduces the motor winding excitation scheme, the model of the LSRM, and the current control method. The LSRM system is modeled as a single-input single-output discrete model with its parameters estimated by the recursive least square (RLS) algorithm. Then, an STR based on the pole placement algorithm is applied to the LSRM for high-performance position tracking. Both the simulation investigation and the experimental veri- fication were conducted. In both cases, the results verified that the proposed RLS algorithm can estimate the parameters with fast convergence. The STR can provide quick response and high precision which is robust to the change of system parameters. Combined with STR control, the LSRM is a low-cost solution to fast, accurate, and reliable position tracking for many demanding motion control applications.
8. S. Mukherjee, G. Poddar, "Fast Control of Filter for Sensorless Vector Control SQIM Drive With Sinusoidal Motor Voltage," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2435-2442, Aug 2007. Full Text Link
Abstract: A pulsewidth-modulated (PWM) voltage applied to a squirrel-cage induction motor (SQIM) can cause high bearing currents, heating of rotor shaft, voltage spike across the motor terminals, etc. Filtering of this PWM voltage to obtain a sinusoidal output voltage can be a solution to this problem. However, a passive $L$–$C$ filter makes the dynamic performance of the drive poor for high-performance control application. In this paper, a feed-forward control strategy for the $L$– $C$ filter is proposed to have a good bandwidth for the filter output voltage. This filter control strategy is introduced along with a sensorless vector control strategy for the SQIM drive. This complete strategy retains the high dynamic performance of the drive even with the $L$–$C$ filter. In this paper, a three-level converter is used as a voltage source inverter for the drive to have a less filter-size requirement. The control strategy is verified on a 7.5-hp SQIM drive with a three-level insulated-gate bipolar-transistor inverter and $L$– $C$ filter. Experimental results validate the high dynamic performance of the drive with filter.
9. S. Shinnaka, T. Sagawa, "New Optimal Current Control Methods for Energy-Efficient and Wide Speed-Range Operation of Hybrid-Field Synchronous Motor," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2443-2450, Aug 2007. Full Text Link
Abstract: This paper proposes new practical optimal current control methods for a newly emerging class of synchronous motors with hybrid rotor fields by both permanent magnet and winding. In a practical situation with limited voltage, the extensively used permanent-magnet synchronous motor hardly achieves an ideal performance in an energy-efficient manner due to its constant magnet field, which simultaneously allows both low-speed high-torque and wide speed-range operations. The hybrid-field synchronous motors (HFSMs) are potential candidates that can achieve the ideal performance as practical motors with controllable hybrid rotor field. HFSMs can dynamically control the rotor flux according to the operation requirements by the low-speed, high-torque, and wide speed-range operations, etc. For the HFSMs, the same torque can be produced by a variety of stator and rotor currents due to the nonlinearity between the torque and the currents. Produced losses and required voltages depend upon the associated currents. Consequently, in the situation that current control systems are well constructed, appropriate determination of a set of stator and rotor current commands plays a key role to achieve the ideal performance in an energy-efficient manner. The proposed methods determine the current commands corresponding to a given torque command such that the total winding copper losses due to the stator and rotor currents can be minimized if the exact currents associated with the torque command exist; the best approximate torque can be produced if no exact associated currents exist, which is, of course, under the circumstance of a voltage limitation. The determined current commands are optimal in the sense of energy efficiency or degree of approximation under voltage limitation. New recursive algorithms searching the optimal current solution in real-time are also given as parts of the methods. The proposed methods are analytical but practical, whose usefulness is verified through exp- eriments.
10. D. Casadei, G. Serra, A. Stefani, A. Tani, L. Zarri, "DTC<> Drives for Wide Speed Range Applications Using a Robust Flux-Weakening Algorithm," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2451-2461, Aug 2007. Full Text Link
Abstract: A control scheme for robust flux-weakening operation of direct-torque-control induction motor drive is proposed. The basic idea is to adjust the flux reference on the basis of the torque error, thus determining a spontaneous flux weakening. To exploit the maximum torque capability, it is necessary to estimate the maximum torque that the induction machine is able to generate at any speed. Initially, a basic version of the algorithm, requiring a simple off-line parameter tuning, is presented. Then, the algorithm is improved and completed with the online estimation of the maximum torque, hence avoiding the initial tuning process. The main features of the proposed methods are a little dependence on machine parameters and a smooth transition into and out of the flux-weakening operation mode. Experimental tests demonstrate the effectiveness of the control schemes.
11. C.-H. Chen, M.-Y. Cheng, "Implementation of a Highly Reliable <>Hybrid Electric Scooter Drive," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2462-2473, Aug 2007. Full Text Link
Abstract: In contrast to hybrid electric cars (HECs), the issues concerning cost, volume, and reliability are even more rigorous when developing hybrid electric scooters (HESs). Therefore, the drive topology and control strategy used in HEC cannot be applied to HES directly. This paper presents a single-stage bidirectional dc/ac converter based on a general full-bridge inverter. The converter is designed for a low-voltage brushless dc motor/alternator (BLDCM/A) used in HESs, in which the additional bulky inductor and power switches are eliminated in the proposed design. In order to increase the reliability of the commutation process, a cost-effective sensorless control scheme for the motor and alternator commutation is developed. The commutation signals are extracted directly from the average terminal voltages, in which the motor neutral voltage, multistage analog filters, analog-to-digital converters, and the complex digital phase-shift (delay) circuits are eliminated. In addition, instead of using the complex flux-weakening control technique, the winding-changeover technique is exploited to extend the range of the operating speed. With attractive features, such as low cost and ease of implementation, the proposed approach is particularly suitable for electric bikes, electric scooters, HESs, etc. Theoretical analysis and several experiments are conducted to justify the effectiveness of the proposed method.
12. Q. Gao, G. Asher, M. Sumner, "Sensorless Position and Speed Control of Induction Motors Using High-Frequency Injection and Without Offline Precommissioning," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2474-2481, Aug 2007. Full Text Link
Abstract: This paper addresses the sensorless speed and position control of induction motors using high-frequency injection at zero and low frequencies. A novel algorithm is presented which allows the rejection of saturation and nonlinear inverter effects without the need for an offline precommissioning process. The method is based on a set of synchronous filters to identify the disturbance waveforms and a memory algorithm that refines the quality of the disturbance waveforms as the motor's operational history is increased. The algorithm is entirely sensorless. Experimental results show sensorless low-frequency operation with and without the memory algorithm.
13. F. BonnetFrancois, P.-E. Vidal, M. Pietrzak-David, "Dual Direct Torque Control of Doubly Fed Induction Machine," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2482-2490, Aug 2007. Full Text Link
Abstract: The main idea developed in this paper is a novel biconverter structure to supply a doubly fed induction machine (DFIM). Two voltage source inverters (VSIs) feed the stator and rotor windings. The outputs of the two VSIs are combined electromechanically in the machine, and as a result, novel features can be obtained. For example, for high power drive applications, this configuration uses two inverters dimensioned for a half of the DFIM power. A new dual direct torque control is developed with flux model of DFIM. Two switching tables linked to VSI are defined for stator and rotor flux vector control. The satisfactory experimental and simulation results are shown, and they confirm good dynamic behavior in four quadrants of the speed-torque plane. Moreover, experimental results show the correct flux vector control behavior and speed tracking performances.
14. Y. Abdel-Rady Ibrahim Mohamed, "A Hybrid-Type Variable-Structure Instantaneous Torque Control With a Robust Adaptive Torque Observer for a High-Performance Direct-Drive PMSM," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2491-2499, Aug 2007. Full Text Link
Abstract: This paper describes a novel instantaneous torque control scheme for a high-performance direct-drive permanent-magnet synchronous motor. The scheme consists of a robust adaptive instantaneous torque observer and a hybrid-type variable-structure instantaneous torque controller. First, to robustly obtain the instantaneous electromagnetic torque information, a robust adaptive torque observer is designed by considering all possible current model uncertainties. The observation gains and uncertainties prediction rules are derived in the sense of Lyapunov theory so that the stability of the proposed estimation scheme is fulfilled. Second, to ensure perfect tracking of the output torque and providing means in eliminating torque ripples, the frequency modes of the disturbances to be eliminated should be included in the stable closed-loop system. To achieve this objective, a hybrid-type variable-structure controller with internal model, for the flux harmonics and system uncertainties, is adopted. The hybrid controller shows better disturbance rejection without control chattering. Comparative evaluation results are presented to demonstrate the validity and effectiveness of the proposed instantaneous torque control scheme.
15. B. Singh, V. Garg, G. Bhuvaneswari, "A Novel T-Connected Autotransformer-Based 18-Pulse AC–DC Converter for Harmonic Mitigation in Adjustable-Speed Induction-Motor Drives," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2500-2511, Aug 2007. Full Text Link
Abstract: This paper presents the design, analysis, and development of a novel autotransformer-based 18-pulse ac–dc converter with reduced kilovoltampere rating, feeding vector-controlled induction-motor drives (VCIMDs) for power-quality improvement at the point of common coupling (PCC). The proposed autotransformer consists of only two single-phase transformers for its realization against three single-phase transformers required in other configurations. The proposed 18-pulse ac–dc converter is suitable for retrofit applications, where, presently, a six-pulse diode bridge rectifier is being used. A set of power-quality parameters, such as total harmonic distortion (THD) and crest factor of ac mains current, power factor, displacement factor, and distortion factor at ac mains, THD of supply voltage at PCC, and dc-bus-voltage ripple factor for a VCIMD fed from an 18-pulse ac–dc converter, are computed to observe its performance. The presented design technique provides flexibility to give an average dc output from the proposed converter, which is the same as that of a conventional three-phase diode bridge rectifier. However, it is also possible to step-up or step-down the output voltage as required. The effect of load variation on VCIMD is also studied to observe the effectiveness of the proposed harmonic mitigator. A laboratory prototype of the proposed autotransformer-based 18-pulse ac–dc converter is developed to validate the design and simulation model.
16. J. Zhang, M. F. Rahman, "A Direct-Flux-Vector-Controlled Induction Generator With Space-Vector Modulation for Integrated Starter Alternator," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2512-2520, Aug 2007. Full Text Link
Abstract: A direct-flux-vector-controlled scheme of induction generator has been proposed in this paper for future 42-V automobile application. The fundamental relationship between the rotating speed of the stator flux vector and torque is analyzed. A simple structure with only one proportional–integral (PI) controller is shown to implement the torque and flux controls adequately. By controlling the electromagnetic torque of the induction machine, the required dc-bus voltage can be well regulated within the 42-V PowerNet specifications. Fixed switching frequency and low torque ripple are obtained with space-vector modulation technique. Simulation and experimental results indicate that the proposed scheme provides a practical solution for an integrated starter alternator other than the widely applied field-oriented-control scheme.
17. Y. Suh, J. K. Steinke, P. K. Steimer, "Efficiency Comparison of Voltage-Source and Current-Source Drive Systems for Medium-Voltage Applications," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2521-2531, Aug 2007. Full Text Link
Abstract: This paper calculates and compares the efficiency and loss distribution in the three most popular state-of-the-art types of large motor drive systems: 1) current-source drive with active front-end rectifier; 2) current-source drive with 18-pulse thyristor rectifier; and 3) three-level voltage-source drive with 12-pulse/24-pulse diode rectifier. For converter systems with efficiencies better than 90%, it is suggested to calculate or measure the losses of all the components separately and add them up to calculate the total efficiency. A simple and accurate method of calculating switching losses for a current-source and voltage-source converter is proposed. Through the calculation and simulation of each loss factor such as switching losses, conduction losses, and snubber and filter losses, the three-level voltage-source drive system has been found to have the highest efficiency of 98.77% under the rated load of 1.6 MW.
18. M. E. Villablanca, J. I. Nadal, "An Efficient Current Distortion Suppression Method for Six-Pulse Bridge Rectifiers," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2532-2538, Aug 2007. Full Text Link
Abstract: In this paper, an efficient current distortion suppression method for six-pulse bridge rectifiers is presented, whereby high-quality waveforms at both ends of the rectifier are possible. The methodology involves accurate shaping of the dc current by using two forced commutated switches. It is demonstrated, theoretically and experimentally, that this action on the dc side is reflected back on the ac side, and as a result, perfect sinusoidal input currents are achieved. In addition, ripple-free voltages and currents are obtained on the dc side by using electrolytic capacitors and smoothing reactors. Rectifying and inverting operations are possible with a simple control circuit, which is also able to both track rapid load variations and overcome failures more efficiently than other modern alternatives. Selected theoretical results are presented, which are fully validated in a laboratory prototype.
19. W. Xiao, W. G. Dunford, P. R. Palmer, A. Capel, "Application of Centered Differentiation and Steepest Descent to Maximum Power Point Tracking," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2539-2549, Aug 2007. Full Text Link
Abstract: This paper concentrates on two critical aspects to improve the performance of maximum power point tracking (MPPT). One improvement is to accurately locate the position of the maximum power point (MPP) by using the centered differentiation. Another effort is to reduce the oscillation around the MPP in steady state by controlling active perturbations. This paper also adopts the method of steepest descent for MPPT, which shows faster dynamic response and smoother steady state than the method of hill climbing. Comprehensive experimental evaluations have successfully illustrated the effectiveness of the proposed algorithm.
20. M. Coleman, C. K. Lee, C. Zhu, W. G. Hurley, "State-of-Charge Determination From EMF Voltage Estimation: Using Impedance, Terminal Voltage, and Current for Lead-Acid and Lithium-Ion Batteries," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2550-2557, Aug 2007. Full Text Link
Abstract: State-of-charge (SOC) determination is an increasingly important issue in battery technology. In addition to the immediate display of the remaining battery capacity to the user, precise knowledge of SOC exerts additional control over the charging/discharging process, which can be employed to increase battery life. This reduces the risk of overvoltage and gassing, which degrade the chemical composition of the electrolyte and plates. The proposed model in this paper determines the SOC by incorporating the changes occurring due to terminal voltage, current load, and internal resistance, which mitigate the disadvantages of using impedance only. Electromotive force (EMF) voltage is predicted while the battery is under load conditions; from the estimated EMF voltage, the SOC is then determined. The method divides the battery voltage curve into two regions: 1) the linear region for full to partial SOC and 2) the hyperbolic region from partial to low SOC. Algorithms are developed to correspond to the different characteristic changes occurring within each region. In the hyperbolic region, the rate of change in impedance and terminal voltage is greater than that in the linear region. The magnitude of current discharge causes varying rates of change to the terminal voltage and impedance. Experimental tests and results are presented to validate the new models.
21. K. Sundareswaran, K. Jayant, T. N. Shanavas, "Inverter Harmonic Elimination Through a Colony of Continuously Exploring Ants," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2558-2565, Aug 2007. Full Text Link
Abstract: In this paper, the authors have developed a novel algorithm for selective harmonic elimination in a pulsewidth-modulated inverter based on the foraging behavior of a colony of ants. The problem of selective harmonic elimination, together with output voltage regulation, is redrafted as an optimization problem, and the solution is sought through the novel concept. The proposed scheme has several advantages, such as computational simplicity, derivative-free operation, and guaranteed near-optimal convergence with random initial guess. It is shown that a newly introduced parameter in the algorithm—quantum of the step movement of ants—largely influences the speed of convergence of the algorithm. Theoretical and practical results are included. Furthermore, the proposed algorithm is compared with the conventional Newton–Raphson method and genetic algorithm, and conclusions are presented.
22. R.-J. Wai, C.-H. Tu, "Development of Lyapunov-Based Genetic Algorithm Control for Linear Piezoelectric <>Ceramic Motor Drive," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2566-2582, Aug 2007. Full Text Link
Abstract: In general, the role of genetic algorithm (GA) is operated offline as a minor compensator or tuner in the control engineering because the systematic design and the latent stability problem of a GA-based control scheme are required to be solved. This paper originally designs a Lyapunov-based GA control (LGAC) scheme, and it applies for a practical control engineering example of the online motion control of a linear piezoelectric ceramic motor driven by a hybrid resonant inverter. In this control scheme, a GA control system via backstepping design technique is utilized to be the major controller, and adaptation laws derived from Lyapunov stability analyses are manipulated to adjust appropriate evolutionary steps. As a result, the system stability can be guaranteed directly without strict constraint conditions and detailed system knowledge. The effectiveness of the proposed drive and control system is verified by experimental results in the presence of uncertainties. From the measured results, the LGAC system performs superior high-precision motion control under wide operation range than conventional backstepping control system.
23. P. Rodriguez, A. V. Timbus, R. Teodorescu, M. Liserre, F. Blaabjerg, "Flexible Active Power Control of Distributed Power Generation Systems During Grid Faults," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2583-2592, Aug 2007. Full Text Link
Abstract: The increasing penetration of distributed power generation into the power system leads to a continuous evolution of grid interconnection requirements. In particular, active power control will play an important role both during grid faults (low-voltage ride-through capability and controlled current injection) and in normal conditions (reserve function and frequency regulation). The aim of this paper is to propose a flexible active power control based on a fast current controller and a reconfigurable reference current selector. Several strategies to select the current reference are studied and compared using experimental results that are obtained during an unsymmetrical voltage fault. The results of the analysis allow selection of the best reference current in every condition. The proposed methods facilitate multiple choices for fault ride through by simply changing the reference selection criteria.
24. J. Gadewadikar, A. Bhilegaonkar, F. L. Lewis, "Bounded $L_{2}$ Gain Static Output Feedback: Controller Design and Implementation on an Electromechanical System," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2593-2599, Aug 2007. Full Text Link
Abstract: In this paper, simplified necessary and sufficient conditions are derived for $H_{infty}$ static output feedback (OPFB). This paper also presents a numerically efficient solution algorithm to solve the coupled design equations for the bounded $L_{2}$ gain static OPFB controller. No initial stabilizing OPFB gain is needed. The effectiveness of the proposed method is demonstrated through implementation on an industrial-type mass spring damper system.
25. P. N. Tekwani, R. S. Kanchan, K. Gopakumar, "A Dual Five-Level Inverter-Fed Induction Motor Drive With Common-Mode Voltage Elimination and DC-Link Capacitor Voltage Balancing Using Only the Switching-State Redundancy—Part I," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2600-2608, Aug 2007. Full Text Link
Abstract: For a dual five-level inverter-fed induction motor (IM) drive, effects of dc-neutral currents on dc-link capacitor voltage fluctuations are analyzed in this paper. Operating limitations in achieving the dual task of common-mode voltage elimination and dc-link capacitor voltage balancing with a single dc power supply are further investigated for the proposed drive. In this paper, an open-loop control scheme, which uses only the availability of redundant switching states for the inverter control, is presented. Limitation of proposed open-loop control to take corrective action for any existing unbalance in capacitor voltages calls for a closed-loop control scheme, which is presented in Part II of this paper.
26. P. N. Tekwani, R. S. Kanchan, K. Gopakumar, "A Dual Five-Level Inverter-Fed Induction Motor Drive With Common-Mode Voltage Elimination and DC-Link Capacitor Voltage Balancing Using Only the Switching-State Redundancy—Part II," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2609-2617, Aug 2007. Full Text Link
Abstract: The open-loop control scheme presented in part I of this paper for a dual five-level-inverter-fed induction motor (IM) drive with two dc power supplies maintains dc-link capacitorvoltage balancing and common-mode voltage (CMV) elimination throughout the operating range of the drive. The operating limitation of the proposed open-loop control scheme to take corrective action toward the existing unbalance in the dc-link-capacitor voltages is also pointed out in part I of this paper. As a solution to this, a simple closed-loop control scheme, which is based only on the switching-state redundancy, is proposed in this part of the paper. The proposed closed-loop control scheme not only prevents further unbalancing of capacitor voltages but also takes corrective actions to bring back the capacitor voltages in the balanced state. The proposed closed-loop scheme achieves dc-link capacitorvoltage balancing and elimination of CMV together in the complete modulation range, including overmodulation of up to the 24-step operation. The proposed control scheme does not affect the output fundamental voltage generated by the inverter, as it effectively utilizes only the availability of redundant switching states of the inverter, and does not call for additional power circuit hardware. The scheme is presented with the simulation studies and experimentally verified with a 1.5-kW open-end winding IM drive.
27. D. P. Marcetic, S. N. Vukosavic, "Speed-Sensorless AC Drives With the Rotor Time Constant Parameter Update," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2618-2625, Aug 2007. Full Text Link
Abstract: This paper presents a new technique for online identification of an induction motor rotor time constant. The technique is designed for a shaft-sensorless indirect field-oriented control induction motor drive with a model reference adaptive system (MRAS)-based speed estimator. The MRAS estimator is sensitive to the changes in the rotor time constant, and online identification of that parameter is essential. If rotor parameter error exists, it does not only change the achieved rotor speed, but it also changes the dynamic behavior of the whole field control and speed estimation structure. The proposed rotor parameter update is exactly based on the newly introduced dynamic model of the potentially detuned MRAS-based speed estimator. The technique avoids the use of test signals and rather extracts the needed information from the ever-present signal jitter, which is inherent to the current and speed servo loops. This paper demonstrates that the phase angle difference between some spectral components of selected small signals within the speed estimator can be used for rotor parameter update. Computer simulations and experiments are performed under a variety of conditions to validate the effectiveness of the proposed rotor parameter update technique.
28. W. Langeslag, R. Pagano, K. Schetters, A. Strijker, A. van Zoest, "VLSI Design and Application of a High-Voltage-Compatible SoC–ASIC in Bipolar <>CMOS<>/DMOS Technology for AC–DC Rectifiers," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2626-2641, Aug 2007. Full Text Link
Abstract: This paper presents an application-specific integrated circuit (ASIC) controller that is suitable for double-stage ac–dc power converters, which employ power-factor correction (PFC) and flyback topologies. The PFC cell is used as a preregulator to comply with line-current harmonic standards, while the flyback converter operates in quasi-resonant (QR)/discontinuous conduction mode to deliver to the load a maximum output power of 120 W. The control functions of the PFC and flyback converters are combined in a unique system-on-chip–ASIC solution to reduce system complexity. The ASIC implements valley-switching control of both the PFC and flyback cells to achieve QR operation. The concept of “valley skipping” is also recalled by the proposed ASIC to determine the operating point in the power-frequency characteristic of the power converter. Depending on the output-power requirement, the ASIC drives the flyback stage into three different states, which result from the combination of the QR and valley-skipping modes. This allows the flyback converter to operate at a fixed on-time, while its off-time is changed according to the output power. The PFC stage is also driven in the QR mode with valley skipping to provide the dc–dc stage with a fixed input voltage of 400 V. To evaluate the performances of the presented ASIC device, a demoboard of a 120-W PFC–flyback system has been realized and tested. Several experimental results have been carried out to confer the validity of the approach that is discussed throughout this paper and to evaluate the performances of the ac–dc rectifier.
29. J.-K. Seok, K.-T. Kim, D.-C. Lee, "Automatic Mode Switching of P/PI Speed Control for Industry Servo Drives Using Online Spectrum Analysis of Torque Command," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2642-2647, Aug 2007. Full Text Link
Abstract: Conventional proportional/proportional–integral (P/PI) speed controller for today's servo drives has to be manually tuned at the controller switching set point by trial and error, which may translate into drive system downtime and a subsequent loss of productivity. The adjustable drive performance is heavily dependent on the quality of expert knowledge. The performance becomes inadequate in applications where the operating conditions change in a wide range, i.e., tracking command, acceleration/deceleration time, and load disturbances. In this paper, we discuss the demands on simple controls/setups for industry servo drives. Analyzing the frequency content of the motor torque command, P/PI speed control mode switching is automatically performed with only a prior knowledge of the mechanical time constant. The dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time over the entire set of operating conditions. For a comprehensive comparison of conventional P/PI control scheme, we carried out extensive tests on an actual servo system.
30. P. N. Tekwani, R. S. Kanchan, K. Gopakumar, "Novel Current Error Space Phasor Based Hysteresis Controller Using Parabolic Bands for Control of Switching Frequency Variations," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2648-2656, Aug 2007. Full Text Link
Abstract: A current error space phasor based simple hysteresis controller is proposed in this paper to control the switching frequency variation in two-level pulsewidth-modulation (PWM) inverter-fed induction motor (IM) drives. A parabolic boundary for the current error space phasor is suggested for the first time to obtain the switching frequency spectrum for output voltage with hysteresis controller similar to the constant switching frequency voltage-controlled space vector PWM-based IM drive. A novel concept of online variation of this parabolic boundary, which depends on the operating speed of motor, is presented. A generalized technique that determines the set of unique parabolic boundaries for a two-level inverter feeding any given induction motor is described. The sector change logic is self-adaptive and is capable of taking the drive up to the six-step mode if needed. Steady-state and transient performance of proposed controller is experimentally verified on a 3.7-kW IM drive in the entire speed range. Close resemblance of the simulation and experimental results is shown.
31. B. Saritha, P. A. Janakiraman, "Sinusoidal Three-Phase Current Reconstruction and Control Using a DC-Link Current Sensor and a Curve-Fitting Observer," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2657-2664, Aug 2007. Full Text Link
Abstract: Successful operation of three-phase current controllers requires measurement of the instantaneous values of phase currents. An innovative method to estimate the three-phase currents from dc-link current is presented. A sinusoidal curve-fitting observer that does not use any of the load parameters is employed. Using the firing signals and the dc-link current for corrective action, the observer generates stable three-phase feedback signals, even during short periods when the phase current information is not present in the dc-link current.
32. M. Mezaroba, D. C. Martins, I. Barbi, "A ZVS PWM Half-Bridge Voltage Source Inverter With Active Clamping," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2665-2672, Aug 2007. Full Text Link
Abstract: This paper presents a zero-voltage (pulsewidth modulation) half-bridge inverter with active voltage clamping using only a single auxiliary switch. The structure is particularly simple and robust. It is very attractive for single-phase high-power applications. Switching losses are reduced due to implementation of the simple active snubber circuit that provides zero-voltage-switching conditions for all switches, which includes the auxiliary one. Its main features are simple modulation strategy, robustness, low weight and volume, low harmonic distortion of the output current, and high efficiency. The principle of operation for steady-state conditions, mathematical analysis, and experimental results from a laboratory prototype are presented.
33. Z. Ye, P. K. Jain, P. C. Sen, "Circulating Current Minimization in High-Frequency AC Power Distribution Architecture With Multiple Inverter Modules Operated in Parallel," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2673-2687, Aug 2007. Full Text Link
Abstract: The control issue of multiple inverter modules operated in parallel is investigated for high-frequency alternative current (HFAC) power distribution architectures, where multiple high-frequency resonant inverters are connected in parallel to the high-frequency high-voltage low-current (HVLC) ac bus, to feed a number of point-of-use power supplies. The circulating current in the multiple inverter system is analyzed first. A novel control scheme is proposed based on the active and reactive current decomposition concept. In the proposed control, there are two loops: 1) the current sharing control loop and 2) the voltage feedback control loop. For the current sharing loop, the active current and reactive current are controlled separately. It is shown that the minimization of the circulating current can be achieved if both the active current and reactive current of the equivalent load are evenly distributed among activated inverter modules. This control method is superior to the scalar control where only the magnitudes of the currents are controlled. Performance is verified with both simulations and experiments on a prototype HFAC power distribution system where two two-stage resonant inverter modules of 500 kHz and 100 W are connected in parallel through small connection inductors to the 500-kHz 28-V rms HFAC bus.
34. A. G. Perry, G. Feng, Y.-F. Liu, P. C. Sen, "A Design Method for PI-like Fuzzy Logic Controllers for DC–DC Converter," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2688-2696, Aug 2007. Full Text Link
Abstract: This paper proposes a novel design procedure of proportional and integral (PI)-like fuzzy logic controller (FLC) for dc–dc converters that integrates linear control techniques with fuzzy logic. The design procedure allows the small signal model of the converter and linear control design techniques to be used in the initial stages of FLC design. This simplifies the small signal design and the stability assessment of the FLC. By exploiting the fuzzy logic structure of the controller, heuristic knowledge is incorporated in the design, which results in a nonlinear controller with improved performance over linear PI controllers.
35. R. Vargas, P. Cortes, U. Ammann, J. Rodriguez, J. Pontt, "Predictive Control of a Three-Phase Neutral-Point-Clamped Inverter," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2697-2705, Aug 2007. Full Text Link
Abstract: A new predictive strategy for current control of a three-phase neutral-point-clamped inverter is presented. The algorithm is based on a model of the system. From that model, the behavior of the system is predicted for each possible switching state of the inverter. The state that minimizes a given quality function $g$ is selected to be applied during the next sampling interval. Several compositions of $g$ are proposed, including terms dedicated to achieve reference tracking, balance in the dc link, and reduction of the switching frequency. In comparison to an established control method, the strategy presents a remarkable performance. The proposed method achieves comparable reference tracking with lower switching frequency per semiconductor and similar transient behavior. The main advantage of the method is that it does not require any kind of linear controller or modulation technique, achieving a different approach to control a power converter.
36. W.-H. Zhu, T. Lamarche, "Velocity Estimation by Using Position and Acceleration Sensors," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2706-2715, Aug 2007. Full Text Link
Abstract: Knowledge of velocity is crucial to certain industrial applications involving high-bandwidth modeling and control. In conventional approaches, the velocities obtained from encoders or tachometers are quite noisy, and low-pass filters are usually engaged to generate usable velocity signals. The low-pass filter, however, causes significant phase lag that can severely affect both modeling and control accuracy in the mid- and high-frequency ranges. In this paper, two approaches using a combination of an encoder and an imperfect accelerometer are proposed to estimate velocities with high bandwidth. The two approaches, namely the two-channel approach and the observer-based approach, estimate velocities by applying proper frequency weightings to the encoder and accelerometer signals. The encoder mainly contributes to the low-frequency components of velocity estimation, and the accelerometer mainly contributes to the high-frequency components of velocity estimation. An adaptive mechanism for estimating the accelerometer gain is also presented. The effectiveness of the two velocity estimation approaches is verified experimentally with respect to a one-degree-of-freedom robot performing both rigid contact modeling and control. Extension to 3-D applications is discussed.
37. Y.-K. Lo, K.-J. Pai, "Feedback Design of a Piezoelectric Transformer-Based Half-Bridge Resonant CCFL Inverter," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2716-2723, Aug 2007. Full Text Link
Abstract: The feedback loop design of a half-bridge resonant inverter based on a piezoelectric transformer (PT) for driving a cold cathode fluorescent lamp (CCFL) is presented in this paper. In order to stabilize the CCFL driving current and luminance, the PT-based resonant inverter incorporating a feedback compensator is designed to track the operating frequency. The dynamic equations and the small-signal model of the presented inverter system are established by using the harmonic approximation and harmonic balance procedures. The feedback compensation is performed by applying the derived small-signal block diagram. The complete mathematical analysis and design considerations are presented in detail. The experimental results agree with the theoretical predictions and confirm the validity of the proposed design approach.
38. H. Mosskull, J. Galic, B. Wahlberg, "Stabilization of Induction Motor Drives With Poorly Damped Input Filters," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2724-2734, Aug 2007. Full Text Link
Abstract: Efficient torque control of induction motor drives in combination with resonant dc-link input filters can lead to a type of stability problem that is known as negative impedance instability. An often-proposed solution to this problem is the nonlinear system stabilizing controller (NSSC). Stability is usually analyzed under the simplifying assumption of perfect torque control. This indicates that the NSSC stabilizes the drive at any operating point. In this paper, however, we show power laboratory experiments where the NSSC stabilization fails. An improved framework for stability analysis and synthesis of stabilization, based on a linear feedback model of the drive, is therefore proposed. With this approach, effects of time delays can easily be included, and stability margins can be directly established from measurements. To solve the indicated problems with NSSC, a stabilization controller that considers the practical limitations of torque control is derived. In the design of the stabilization controller, the tradeoff between damping and acceptable torque control is also explicitly taken into account. The proposed stabilization scheme is implemented and evaluated on a hardware-in-the-loop simulator as well as in a power laboratory. The results show that the proposed method outperforms the NSSC method.
39. H. Ding, J. Wu, "Point-to-Point Motion Control for a High-Acceleration Positioning Table via Cascaded Learning Schemes," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2735-2744, Aug 2007. Full Text Link
Abstract: In this paper, effort is devoted to point-to-point motion control for the high-acceleration positioning table driven by linear motors. New performance indices for point-to-point motion are first introduced. Then, a cascaded controller is designed. It consists of an inner loop velocity PI controller and an outer loop position P plus A-type iterative learning controller. In the subsequence, the convergence analysis in both time and frequency domains is given. The control strategy has the property that only the position signal is required in the outer loop. With the common motion profiles, i.e., T-curve and S-curve, and partial knowledge of the system, point-to-point motion experiments are carried out. The maximum acceleration of the motion profile is 0.04 $hbox{mm/ms}^{2}$ (about 4.07 g), and the maximum velocity is 0.4 mm/ms. Experimental results illustrate that the proposed controller can greatly improve the performance, and the S-curve motion profile has advantages over the T-curve one.
40. Q.-V. Tran, T.-W. Chun, J.-R. Ahn, H.-H. Lee, "Algorithms for Controlling Both the DC Boost and AC Output Voltage of Z-Source Inverter," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2745-2750, Aug 2007. Full Text Link
Abstract: This paper aims to achieve good performance for both the dc boost and the ac output voltage control of the Z-source inverter (ZSI). The algorithm to control linearly the capacitor voltage is suggested in order to improve the transient response for dc boost control of the ZSI. The peak value of the ac output voltage is used to control exactly the ac output voltage to its desired level. A modified space vector pulsewidth modulation scheme is applied to control the shoot-through time for boosting dc voltage. The proposed algorithms are verified with simulation and experiment with a 32-bit digital signal processor.
41. H.-J. Chiu, S.-J. Cheng, "LED Backlight Driving System for Large-Scale LCD Panels," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2751-2760, Aug 2007. Full Text Link
Abstract: This paper presents an LED backlight driving system for large-scale liquid crystal display panels. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by using a single-stage charge-pump asymmetrical half-bridge converter. To regulate the LED current and brightness for the LED backlight system, some current sharing methods are presented and compared. The requirements for the current sharing and luminance balance among paralleled LED arrays can be satisfied while current ripple is eliminated significantly. Because of the addition of bypass diodes, an alternative current path can be offered when a single LED fails. The LED array will not be extinguished. Reliability of the LED backlight system can thus be improved effectively. A laboratory prototype has been built and tested. The simulation and experimental results are shown to verify the feasibility of the proposed method.
42. S. Lakshminarayanan, G. Mondal, P. N. Tekwani, K. K. Mohapatra, K. Gopakumar, "Twelve-Sided Polygonal Voltage Space Vector Based Multilevel Inverter for an Induction Motor Drive With Common-Mode Voltage Elimination," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2761-2768, Aug 2007. Full Text Link
Abstract: In this paper, a 12-sided polygonal voltage space vector generation with common-mode voltage elimination (CME) is proposed for an induction motor drive. An open-end winding configuration is used for the motor. The proposed multilevel structure is achieved by cascading only the conventional two-level inverters with asymmetrical dc link voltages. By appropriately selecting the voltage vectors with identical common-mode voltage from the opposite ends, a pulsewidth modulation (PWM) strategy with zero common-mode voltage variation can be achieved for the entire modulation range with a common dc link requirement for both the inverter systems. Along with the CME, the proposed 12-sided polygonal space vector based multilevel inverter structure has increased modulation range with the absence of 5th, 7th, 17th, 19th, etc., harmonics up to 12-step operation. The bandwidth problems associated with conventional hexagonal voltage space vector structure current controllers due to the presence of 5th and 7th harmonics in the overmodulation region are absent in the present 12-sided structure. So a simple PWM voltage control with linear voltage control up to 12-step operation is possible from the present 12-sided scheme with less current control complexity.
43. K.-Y. Lian, C.-H. Chiang, H.-W. Tu, "LMI-Based Sensorless Control of Permanent-Magnet Synchronous Motors," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2769-2778, Aug 2007. Full Text Link
Abstract: A sensorless speed tracking control scheme for permanent-magnet synchronous motors (PMSMs) is presented in this paper. This efficient scheme provides the exponential convergence on estimation errors of rotor's speed and position, and tracking error of rotor's speed. First, the Takagi–Sugeno fuzzy model is used to represent the nonlinear system of PMSMs. Then, a state observer is constructed to estimate the rotor's speed and position in the manner of exponentially convergent rate. For converting the tracking control into a stabilization problem, a new and novel control design called virtual-desired variable synthesis is proposed to define the internal desired states. Consequently, the practical controller is derived under some adequate assumptions; meanwhile, the feedback gains and the observer gains are obtained separately by solving a set of linear matrix inequalities pertaining to system stability. The performance of the proposed sensorless algorithm is verified by experiments of PMSMs for speed tracking.
44. K.-B. Park, C.-E. Kim, G.-W. Moon, M.-J. Youn, "Voltage Oscillation Reduction Technique for Phase-ShiftFull-Bridge<> <>Converter," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2779-2790, Aug 2007. Full Text Link
Abstract: A conventional phase-shift full-bridge (PSFB) converter has a serious voltage oscillation problem across the secondary rectifier diodes. To overcome this problem, a new voltage oscillation reduction technique (VORT), which effectively reduces the rectifier voltage oscillation by a simple nondissipative manner, is proposed. The concept of VORT is to utilize the operation of leading-leg transition, which does not cause severe rectifier voltage oscillation, to the lagging-leg transition. It is simply implemented by employing only a resonant capacitor in series with the transformer secondary and a small magnetizing inductance of the transformer without any lossy components. Moreover, the VORT can realize zero-voltage switching for all switches over a wide load range using the energy that is stored in the transformer magnetizing inductor and output filter inductor. The concept, operational principle, oscillation analysis, and design considerations of VORT are presented and verified experimentally.
45. S. A. Gonzalez, R. Garcia-Retegui, M. Benedetti, "Harmonic Computation Technique Suitable for Active Power Filters," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2791-2796, Aug 2007. Full Text Link
Abstract: The design and implementation of a novel method for reference generation that is applied to active power filters (APFs) is introduced in this paper. The proposed reference generation performs harmonic detection based on the Goertzel algorithm. The method computes both the module $I_{1}$ and the phase $varphi$ of the signal, with minimum computation overhead. This makes the method suitable for APFs or other applications that require harmonic detection. A comparison analysis between the discrete Fourier transform and the proposed method is carried out. The proposed reference generator is implemented using a digital signal processor and tested with waveforms from typical load currents. Experimental results are obtained under both stationary and transient states.
46. Z Ye, P Jain, P Sen, "A Two-Stage Resonant Inverter With Control of the Phase Angle and Magnitude of the Output Voltage," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2797-2812, Aug 2007. Full Text Link
Abstract: A high-efficiency two-stage resonant inverter with effective control of both the magnitude and phase angle of the output voltage was proposed in this paper for high-frequency ac (HFAC) power-distribution applications, where a number of resonant inverters need to be paralleled. In order to parallel multiple resonant inverters of the same operation frequency, each inverter module needs independent control of the phase angle and magnitude of the output voltage. It is also desirable that the output voltage has very low total harmonics distortion, as well as high efficiency over wide input and load ranges. The proposed resonant inverter consists of two stages. The first stage is a two-switch dc/dc converter with zero-voltage transition, and the second stage is a half-bridge resonant dc/ac inverter with fixed duty ratio. A series–parallel resonant tank is used to achieve high waveform quality of the output voltage. The magnitude of the output voltage is regulated through the duty-ratio control of the first stage with pulsewidth modulation. The phase angle of the output voltage is regulated through a pulse-phase-modulation control of the second stage. The proposed resonant inverter has the advantages of better waveform quality, wide range of input and load variations for soft-switching, and independent control of the phase angle and magnitude of the output voltage, making it an attractive candidate for applications where a number of resonant inverters need to be placed in parallel to the HFAC bus and a number of distributed loads are connected to the HFAC bus. The performance is verified with both simulation and experiments.
47. B.-R. Lin, F.-Y. Hsieh, "Soft-Switching Zeta–Flyback Converter With a Buck–Boost Type of Active Clamp," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2813-2822, Aug 2007. Full Text Link
Abstract: This paper presents the system analysis, design consideration, and implementation of a soft-switching zeta–flyback converter to achieve zero-voltage switching (ZVS). In the proposed converter, the zeta and flyback topologies are adopted in the output side to achieve the following features: to share the power components in the transformer primary side, to achieve the partial magnetizing flux reset, and to share the output power. The buck–boost type of active clamp is connected in parallel with the primary side of the isolation transformer to recycle the energy stored in the leakage inductor of isolated transformer and to limit the peak voltage stress of switching devices due to the transformer leakage inductor when the main switch is turned off. The active clamp circuit can make the switching devices to turn on at ZVS. Experimental results taken from a laboratory prototype rated at 240 W, input voltage of 150 V, output voltage of 12 V, and switching frequency of 150 kHz are presented to demonstrate the converter performance. Based on the experimental results, the circuit efficiency is about 90.5% at rated output power, and the output voltage variation is about 1%.
48. H. (n. J.) Koskimaki, P. Laurinen, E. Haapalainen, L. Tuovinen, J. Roning, "Application of the Extended $k$nn Method to Resistance Spot Welding Process Identification and the Benefits of Process Information," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2823-2830, Aug 2007. Full Text Link
Abstract: Resistance spot welding is used to join two or more metal objects, and the technique is widely used in, for example, the automotive and electrical industries. This paper introduces the use of the $k$-nearest-neighbor ($k$nn) method to identify similar welding processes. The two main benefits achieved from knowing the most similar process are the following: 1) The time needed for the setup of a new process can be substantially reduced by restoring the process parameters leading to high-quality joints, and 2) the quality of new welding spots can be predicted and improved using the stored information of a similar process. In this paper, the basic $k$nn method was found to be inadequate, and an extension of the $k$nn method, which is called similarity measure, was developed. The similarity measure provides information of how similar the new process is by using the distance to the $k$nns. Based on the results, processes can be classified, and the similarity measure proved to be a valuable addition to the existing methodology. Furthermore, process information can provide a major benefit to welding industry.
49. Z. Ye, P. K. Jain, P. C. Sen, "A Full-Bridge Resonant Inverter With Modified Phase-Shift Modulation for High-Frequency AC Power Distribution Systems," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2831-2845, Aug 2007. Full Text Link
Abstract: The design of a resonant inverter for high-frequency ac (HFAC) power distribution systems is complicated by the following three factors: 1) A number of electronic loads located in different locations are connected to the resonant inverter, the impedance, and the power factor of the equivalent load of which varies over a wider range than a system with a certain load; 2) the resonant inverter is subject to an input-line voltage varying over a wide range; and 3) the characteristics of the resonant inverter depend on the load impedance. It is mandatory to operate the inverter with zero-voltage switching under various load conditions of different power factors and over wide input variations. It is further desirable that multiple resonant inverters can be paralleled with simple current-sharing control (CSC). A phase-shift-modulation (PSM)-controlled full-bridge series-parallel resonant inverter is proposed for the HFAC power distribution architectures. A new PSM method is proposed with which the phase angle of the inverter output voltage is independent of the modulation signal of the phase-shift modulator. Such a feature allows multiple resonant inverters to operate in parallel with a magnitude CSC. The resonant inverter is analyzed with a general nonresistive load model, and the design curves are developed. A prototype resonant inverter system is designed and implemented with an operation frequency of 1 MHz, a rated output power of 150 W, and a sinusoidal output voltage of 1-MHz 28-V rms. The proposed resonant inverter has the advantages of high efficiency over wide input/output line variations, high waveform quality of the output voltage, and phase-angle independence of the voltage-feedback/feed-forward control and CSC.
50. C.-W. Hung, C.-T. Lin, C.-W. Liu, J.-Y. Yen, "A Variable-Sampling Controller for Brushless DC Motor Drives With Low-Resolution Position Sensors," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2846-2852, Aug 2007. Full Text Link
Abstract: This paper proposes a variable-sampling variable structure controller (VSC) for brushless dc (BLDC) motor drives with low-resolution position sensors (Hall sensors). The variable-sampling characteristics arising from the situation where measurements depend on the path-embedded sensors will result in the uncertainty of the discrete-time models. To circumvent this issue, a modification of the conventional discrete-time VSC control law for BLDC motor drives with Hall sensors is derived to achieve the robustness of speed control. Three measurement error-mitigation methods are also presented to reduce the errors due to low-resolution position feedback. Both simulated and experimental results confirm the effectiveness of the proposed controller and error-mitigation techniques.
51. C. Demoulias, K. Gouramanis, "Voltage Multiple-Zero-Crossings at Buses Feeding Large Triac-Controlled Loads," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2853-2863, Aug 2007. Full Text Link
Abstract: Triac-controlled loads operating in three-phase four-wire electric networks produce large zero-sequence current harmonics that cause large currents in the neutral conductor. Under certain conditions, the phase-to-neutral voltage (PTNV) at the bus feeding a large triac-controlled load is distorted to such a degree that multiple zero crossings (MZC) appear in the voltage waveform. This situation may cause malfunction of the triac control systems or any other control systems that are based on the detection of voltage zero crossings. The influence of various parameters of the triac-controlled load and of the cable feeding it, on the appearance of voltage MZC, is investigated. A simulation model is built with alternative transients program version of Electromagnetic Transients Program and is validated by comparison with measurements taken at a real theatrical lighting installation controlled by triacs. The occurrence of MZC in the voltage waveform is also explained by an analytical approximation. It is shown that certain cable configurations should be avoided when feeding large triac-controlled loads, or otherwise, MZC will appear in the PTNV.
52. Y. A.-R. I. Mohamed, "A Newly Designed Instantaneous-Torque Control of Direct-Drive PMSM Servo Actuator With Improved Torque Estimation and Control Characteristics," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2864-2873, Aug 2007. Full Text Link
Abstract: In this paper, a newly designed instantaneous-torque-control scheme with improved instantaneous-torque estimation and control characteristics in a direct-drive permanent-magnet synchronous motor (DD-PMSM) is presented. A hybrid control structure that combines the internal-model principle and the variable-structure control approach is proposed. The appropriate control voltage vector is determined using the control effort of the variable-structure torque and $d$-axis current controllers combined with the estimated dynamic back-EMF vector in a feedforward control manner. Subsequently, the dynamic back-EMF vector, which contains the flux-harmonics information, is included in the reference voltage generation as an internal model. As a result, better disturbance rejection can be obtained with the proposed cascaded control structure. To robustly obtain the instantaneous-torque information, an adaptive motor model is proposed. The adaptive model is realized by adopting recursive estimators to estimate unknown machine electrical quantities and parameters. In addition to its robust estimation performance, the proposed adaptive model includes the dynamic model of the estimated disturbance to enhance the estimation characteristics. Experimental results are presented to demonstrate the validity and effectiveness of the proposed instantaneous-torque-control scheme.
53. K. D. Papastergiou, D. E. Macpherson, "An Airborne Radar Power Supply With Contactless Transfer of Energy—Part I: Rotating Transformer," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2874-2884, Aug 2007. Full Text Link
Abstract: Reliability and precision are key requirements for electronic systems in aerospace applications. Transferring electrical energy from a stationary to a moving device involves wearable parts such as slip rings and brushes. This paper examines the possibility of using a rotating transformer for contactless transfer of energy from the base to the revolving platform of an airborne radar system. The first part of the series focuses on the magnetic interface, investigating its electrical properties and their association with the core and windings geometry. The reader will gain an understanding of the merits and limitations of this technology and will be able to assess its suitability for other applications. The effects of the increased leakage and reduced magnetizing inductances of the transformer are investigated, and two winding layouts are proposed and characterized by measurements and finite-element analysis. Some equations are presented along with practical guidelines on designing a rotating transformer with a 0.25–2-mm air gap. The transformer voltage gain and efficiency plots are introduced as performance-assessment tools. The impact of the air-gap stray flux on the winding conduction losses is shown, and some electromagnetic-compatibility considerations are presented. Finally, a mechanical layout for a 1-kW rotating transformer is proposed.
54. K. D. Papastergiou, D. E. Macpherson, "An Airborne Radar Power Supply With Contactless Transfer of Energy—Part II: Converter Design," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2885-2893, Aug 2007. Full Text Link
Abstract: A magnetic link is established between the stationary and revolving frames of a radar system by means of a rotating transformer. Based on the magnetics analysis of Part I of the series, a design methodology is proposed for integrating a rotating transformer into a power electronic converter using the efficiency and voltage gain plots. It is shown that a phase-shifted full-bridge topology can effectively utilize the parasitic components of the transformer. The increased magnetizing current assists the resonant transition, and this, in turn, compensates for the increased conduction losses that a rotating transformer yields. The proposed design method secures the soft-switching operation of the converter over the entire load range and allows efficient operation and reduced electromagnetic emissions. The methodology is evaluated experimentally, and the resulting prototype demonstrates an average efficiency of 92.6% in the 0.2–1-kW output power range. The proposed topology extends the power capacity of the rotating transformer without compromising its size, cost, or performance. A comparison between the slip rings and rotating transformer solutions highlights the merits and weaknesses of each technology.
55. S. Kouro, J. Rebolledo, J. Rodriguez, "Reduced Switching-Frequency-Modulation Algorithm for High-Power Multilevel Inverters," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2894-2901, Aug 2007. Full Text Link
Abstract: Multilevel inverters have emerged as attractive high-power medium-voltage power-conversion systems. They are mainly controlled with high-frequency pulsewidth-modulation methods. This is not suitable for very high-power application due to significant switching losses. This paper presents an adaptive duty-cycle modulation algorithm that reduces the switching frequency to a minimum necessary to fulfill the dynamic requirements of the system. Switching losses are, therefore, strongly reduced. This is achieved by using the slope of the voltage reference to adapt the modulation period to ensure that only one-step change between two voltage levels. Simulation and experimental results are presented for a nine-level cascaded inverter. Voltage waveforms obtained for variable frequencies and amplitudes show similar switching patterns, with a reduced and near-constant number of commutations per cycle, regardless of the reference frequency and amplitude.
56. I. Etxeberria-Otadui, U. Viscarret, M. Caballero, A. Rufer, S. Bacha, "New Optimized PWM VSC Control Structures and Strategies Under Unbalanced Voltage Transients," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2902-2914, Aug 2007. Full Text Link
Abstract: Control structures and strategies have a critical influence on a power electronic converter's behavior during disturbances. Most of the previous works in the field of pulsewidth modulation voltage-source converter (VSC) operation under unbalanced conditions propose dual vector controllers with dc bus voltage optimization strategies, which have been proven to be well adapted for rectifier applications. In this paper, two major contributions are made. On the one hand, a new optimized operation strategy based on exchanged power maximization is proposed for vector control structures, which permits the extension of optimized operation to other VSC applications (e.g., flexible alternating current transmission system and distributed generation interfaces). On the other hand, a scalar control structure is proposed based on resonant controllers, together with three adapted optimized operation strategies, namely: 1) dc bus voltage optimization; 2) power exchange maximization; and 3) a hybrid strategy (an intermediary mode between the other two strategies). Their main advantage is their simplicity and the lack of real-time symmetrical component extraction techniques. This scalar controller and the proposed optimized operation strategies are compared to conventional vector controllers. It is proven through experimental analysis that the proposed scalar controller offers very good performances with simpler structures and bigger flexibility in terms of operation modes.
57. H.-J. Chiu, S.-J. Cheng, "Single-Stage Voltage Source Charge-Pump Electronic Ballast With Switched-Capacitor Dimmer for Multiple Fluorescent Lamps," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2915-2918, Aug 2007. Full Text Link
Abstract: This paper presents a single-stage electronic ballast for driving multiple fluorescent lamps in which a dimming control scheme is proposed to regulate the lamp current. A laboratory prototype is built and tested, and it is found that the unity power factor can remain under individual lamp brightness control. The experimental results are therefore shown to verify the feasibility of the proposed method.
58. T. B. Marchesan, M. A. Dalla-Costa, J. M. Alonso, R. N. do Prado, "Integrated Zeta–Flyback Electronic Ballast to Supply High-Intensity Discharge Lamps," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2918-2921, Aug 2007. Full Text Link
Abstract: This paper proposes a metal halide lamp electronic ballast based on the integration of Zeta and Flyback converters, which are used to achieve power factor correction and lamp current stabilization, respectively. The proposed integrated converter allows to reduce the number of ballast components without increasing the current stress in the shared switch. Thus, the lamp is supplied with a low-frequency square waveform that avoids the acoustic resonance phenomenon. The proposed topology has been implemented and validated by experimental results.
59. C. S. Edrington, B. Fahimi, M. Krishnamurthy, "Correction to “An Autocalibrating Inductance Model for SwitchedReluctance Motor Drives”," IEEE Trans. on Industrial Electronics, vol. 54, no. 4, pp. 2921-2921, Aug 2007. Full Text Link
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