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This paper simply investigates experimentally multiple “rotor” bar current waveforms at standstill, on a dedicated inverted induction motor prototype as a basis to analyze the bar currents distribution in the symmetrical and unsymmetrical cage. A phasor calculus scheme based on primary magneto-motive-force space harmonics is developed to explain this asymmetry of bar currents system at standstill even for a symmetrical cage. The results of the paper should be a strong experimental foundation to investigate thoroughly the effects of rotor speed and loading and of broken bars on additional losses, torque pulsations, noise, and vibrations in high performance induction machines. [ABSTRACT FROM PUBLISHER]

A novel hybrid pulse width modulation (PWM) technique is proposed in this paper for two parallel interleaved, two-level, three-phase voltage source inverters (VSIs). The two parallel interleaved VSIs are analyzed as a three-level (3L) inverter. A 3L inverter provides minimum line current ripple when nearest three voltage vectors are applied. In this paper, a novel carrier-based PWM technique is developed that ensures the application of nearest voltage vectors, keeping average circulating current to zero over a switching period. For carrier-based implementation of the proposed PWM, generalized common-mode (CM) offsets are derived in terms of maximum and minimum values of reference signals. Each 3L space-vector sector is divided into seven subsectors. For each subsector, a CM offset is calculated, addition of which to reference signals ensures the minimum line current ripple and zero average circulating current. Simulation and experimental results are provided to validate the proposed technique. [ABSTRACT FROM PUBLISHER]

Recently, a series elastic actuator (SEA) has emerged as a potential actuator system for various robotic applications where safe and precise interactive force control is required. Even though lots of research has been conducted on the mechanical/controller design and the development of applications for SEAs, the accurate force observation issue has not been highlighted much. Only the simple law, that is, the spring in an SEA can measure interactive force has been repeatedly mentioned and utilized. However, this is not true when the load-side dynamics affects the spring deformation significantly. This paper tackles this problem by demonstrating the imprecise force observation of the spring deformation and proposing two types of external force observers to address the problem. A reaction force-sensing SEA (RFSEA) is adopted in this paper, and its dynamic characteristic is analyzed in detail using the Lagrangian mechanics. Based on the analyzed dynamics, force observers are designed and verified through simulations and experiments. An XY stage driven by RFSEAs is developed so that the stage can be force controlled, and the proposed force observers are applied to this. Human interactive forces on the developed XY stage, the impedance of which is controlled in several ways, are estimated and compared with a force plate. Various experimental results validate the performance and potential of the proposed force observer for SEA systems. [ABSTRACT FROM PUBLISHER]

In a standalone hybrid wind-diesel-battery system, the battery lifetime is often optimistically over-predicted by hybrid system designers and battery manufacturers. As a result, battery replacement takes place more often than required. One of the reasons is due to the underestimation of battery wear from the short charge–discharge cycles, otherwise known as microcycles. A microcycle takes place when the power generation closely matches the load demand. The detrimental effect of microcycles on a battery-based standalone hybrid renewable energy system was previously investigated, however, only from the perspective of short-term renewable energy fluctuations. This research paper provides a new insight on the battery lifetime reduction, resulting from microcycles that are generated through the tower shadow phenomena. Downwind wind turbines are considered here, as their tower shadow effects are more significant compared to the upwind counterpart. This paper briefly presents the modeling of tower shadow profiles for both tubular and four-leg tower configurations. Experimental results have shown that the microcycles due to this nonideal effect are significant in a battery-based standalone hybrid system. The quantification of the battery lifetime reduction due to this effect is demonstrated. Finally, the paper concludes with a sensitivity analysis of the battery lifetime reduction for different tower configurations, operating at different load conditions. [ABSTRACT FROM PUBLISHER]

This paper presents an experimental study on the ageing of insulated-gate bipolar transistor (IGBT) power modules. The aim is to identify the effects of power cycling on these devices with high baseplate temperatures (60 ^\circ\C to 90 ^ \circ\C) and wide temperature swings (60 ^\circ \C to 100 ^\circ\C). These values for thermal stresses have been defined according to automotive applications. The test conditions are provided by two types of test benches that will be described in this paper. The changes in electrical and thermal indicators are observed regularly by a monitoring system. At the end of the test (reaching damage criterion or failure), different analyses are performed (acoustic scanning and SEM imaging), and the damage is listed systematically. Nineteen samples of 600-V 200-A IGBT modules were thus aged using five different power-cycling protocols. The final summary of results shows that ageing mechanisms mainly concern wire bonds and emitter metallization, with gradual impact depending on protocol severity. [ABSTRACT FROM AUTHOR]

The sensorless position control of permanent-magnet (PM) synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper, the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated d-axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency q current component. We propose a new approach that also exploits the d-axis high-frequency current component and allows working with injected voltage signal of reduced amplitude, thus reducing noise and additional losses. The main contribution of this paper relies in the compensation of the motor end effects due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because they cause an error in the position estimation that varies with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in this paper. Last, a simplified integral-type controller is used to estimate motor position instead of the commonly adopted proportional–integral controller plus integrator, and this requires a low-effort design. Experiments on a linear tubular PM synchronous-motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique. [ABSTRACT FROM AUTHOR]

For the case of unbalanced grid voltages, active power of pulse width modulation (PWM) rectifier is reduced due to the current limitation of power switches. Under unbalanced grid voltages, two existing control methods for the PWM rectifier are widely adopted, one for instantaneous active power control, and the other for balanced positive sequence current control. To maximize the PWM rectifier instantaneous active power capability and minimize active power oscillations during voltage dips, a control method combining balanced positive sequence and instantaneous active power control is proposed. The limitations of these two control methods are given, and the fluctuations on active and reactive power using the proposed control method are discussed in detail in this paper. The analysis in this paper is based on p.u. system, and some conclusions are drawn. Corroboration of the expected features of the proposed control method is carried out by means of experiments. [ABSTRACT FROM PUBLISHER]

In this paper, we propose an approach for integrating a series filter inductance in a coaxially wound transformer (CWT) as a potential alternative to conventional solenoidally wound transformers (SWT) for high-power isolated soft-switching dc–dc converters. The critical elements that determine the size and the performance of soft-switching dc–dc converters are the isolation transformer and the filter elements. While conventional SWTs using a stray magnetic field as a filter inductance often suffer from a considerably increased loss, heat congestion, and electromagnetic interference, a CWT is rarely affected by high frequency and fringing effects. The desired properties are still valid while the required filter inductance is fully integrated with an isolation transformer using the proposed method. In addition, the evenly distributed magnetic fields in a concentric geometry enable accurate electrical and mechanical analysis and a specific application-oriented design. In this paper, the operating principles, design procedure, and loss modeling of a CWT with an integrated filter inductance are introduced. Its functionality and suitability for high-frequency applications were proven by theoretical analysis and experiments. A prototype transformer with an integrated inductance 4 mH was facilitated and evaluated in a 15 kV-SiC mosfet-based 6 k–400 Vdc stage for a solid-state transformer of up to 6.5 kW at a switching frequency of 20 kHz. [ABSTRACT FROM PUBLISHER]

High dc voltage utilization is one of the important requirements in a three-phase inverter. Under some carrier-based pulse width modulations (PWMs), the dc voltage utilization can reach the same maximum as that under the space vector modulation. But the third harmonic component of common-mode voltage (CMV) will be increased markedly while using these carrier-based PWMs in inverters. To improve the situation, this paper proposes that a midpoint-fluctuation carrier (MFC) scheme should be used in the three-phase inverter. The MFC is formed by adding a midpoint-fluctuation signal on the standard symmetrical triangular carrier. By analyzing the linear modulation region of the midpoint-fluctuation signals, a minimum fluctuant signal in the linear modulation region is designed in the paper. Compared with the use of other conventional schemes in the three-phase inverter, the use of minimum MFC scheme has higher fundamental amplitude in the output line voltage and smaller magnitude of the third harmonic in the CMV. The feasibility and validity of the MFC are proved by experiment results in a three-phase inverter. [ABSTRACT FROM PUBLISHER]

Bearing fault diagnosis is of significance to enhance the reliability and security of electric locomotive. In this paper, a novel convolutional deep belief network (CDBN) is proposed for bearing fault diagnosis. First, an auto-encoder is used to compress data and reduce the dimension. Second, a novel CDBN is constructed with Gaussian visible units to learn the representative features. Third, exponential moving average is employed to improve the performance of the constructed deep model. The proposed method is applied to analyze experimental signals collected from electric locomotive bearings. The results show that the proposed method is more effective than the traditional methods and standard deep learning methods. [ABSTRACT FROM PUBLISHER]

Due to the widely used dc characterized loads and more distributed power generation sources, the dc nanogrid becomes more and more popular, and it is seen as an alternative to the ac grid. For safety considerations, the dc nanogrid should provide reliable grounding for the residential loads such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck–boost ac/dc converter for use in the united-grounding-configuration-based dc nanogrid with three terminal outputs is proposed. The working principle of this converter is presented in detail through analyzing the equivalent circuits. Experiments are carried out to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

Currently, the development of a leading-edge technology for saving and reproducing human motions in terms of haptic information is required for various fields. To address these requirements, a motion-copying system has already been proposed. This system is a key technology that enables the realization of the acquisition, preservation, and reproduction of real-world haptic information. In order to apply this system to various fields, the use of the concept involving two types of coupling is important: that involving spatial and temporal couplings. In this paper, the use of the concept mentioned earlier is proposed, and the related system is named “spatiotemporal coupler.” The proposed coupler is divided into two couplers. One is a spatial coupler, and the other is a temporal coupler. The spatial coupler connects human motions that are saved by haptic devices with different configurations according to the information for a human model. On the other hand, the temporal coupler integrates the saved motions temporally, and the integrated motion is reproduced as a single motion. The proposed concept is applied to finger motion in the experiments. The experimental results validate the proposed technology. [ABSTRACT FROM PUBLISHER]

Pulsewidth modulation (PWM) strategies and methods for multilevel converters are usually developed for series converters. One of the aims of this paper is to show that they may be applied to parallel converters using interleaving techniques, given that these converters also have multilevel characteristics. PWM methods based on carriers' disposition and on zero sequence injection are studied for parallel multilevel inverters. Analysis show that the best method in terms of load current ripple (phase disposition (PD) centered space vector PWM) has, nevertheless, a bad influence on the current balancing between commutation cells of the same phase. Another objective is to analyze these problems and to propose a solution to cancel current imbalance when using PD strategy. Experimental results validate the analysis presented in this paper as well as the compensation of band transition of the differential mode current observed when PD strategy is used. [ABSTRACT FROM PUBLISHER]

Numerous studies have been carried out to compensate or eliminate the dead-time effect. This paper analyzes the limitations of the previous compensation or elimination schemes. Then, a novel mixed pulsewidth-modulation scheme for dead-time elimination and compensation is proposed for the grid-tied inverter. The proposed scheme implements the dead-time elimination in most of the grid current fundamental period but switches to the conventional dead-time compensation around the zero-crossing point. In this way, a safe and efficient dead-time effect elimination method is achieved. Furthermore, this paper proposes to determine the switching point and the compensation direction by the grid current modulation function. Experimental results are given to demonstrate the validity and features of the proposed method. [ABSTRACT FROM AUTHOR]

A new bidirectional dc–dc converter composed of two class-E resonant converters is presented in this paper. Bidirectional power flow is controlled by transistor control pulse frequency changes, with a constant break between the succeeding pulses as in quasi-resonant converters. The boost or buck mode converter operation depends on the mutual relation between the control pulses of the transistor pairs which are located diagonally in the converter bridge. The advantages of the system involve are high operation frequency (200 and 450 kHz) and zero value of the transistor switching losses. This paper includes an analytical description that is useful for the converter design. The investigations are confirmed by PSpice simulations and an experiment of a laboratory model (1.6 kW). [ABSTRACT FROM AUTHOR]

This paper proposes a new robust controller in a stationary reference frame for doubly fed induction generators (DFIGs) of grid-connected wind turbines. Initially, a DFIG dynamic model is derived from the voltage and flux equations in \alpha\beta coordinates, where uncertainties and disturbances intrinsic to the system are accounted for as perturbation terms are added to the nominal model. Then, a controller design procedure that guarantees the DFIG stability under uncertainties and disturbances at the grid side is presented in detail. It is demonstrated that a very fast dynamic behavior can be obtained with the proposed controller, which improves the transient response of the grid-connected DFIG, particularly under conditions of unbalanced voltage dips resulting from asymmetrical network faults. In order to conform with the fault ride-through capability requirements, this paper proposes a new reference strategy, which is divided into normal and fault operation modes. Experimental results are given to support the theoretical analysis and to illustrate the performance of the grid-connected DFIG with the proposed controller. [ABSTRACT FROM AUTHOR]

This paper presents a novel topology for a direct ac–ac power converter, called as the “three-to- k” phase matrix converter. The input to the proposed matrix converter configuration is a three-phase fixed voltage and a fixed frequency supply from the grid. The output is a variable voltage and variable frequency ac supply of any number of phases (k phase). However, the discussion is limited here for a k that is equal to odd number of phases. As an example, a “three-to-five” phase matrix converter is utilized for discussion and analysis. This paper also proposes two pulsewidth modulation (PWM) control techniques for the general topology of the “three-to- k” phase matrix converter. This is based on the so-called direct duty ratio PWM (DPWM). In one presented technique, the output voltage is limited to one half of the input voltage. For the other proposed scheme, the output voltage is enhanced to 78.86% of the input voltage. The proposed control algorithm is validated using simulation and an experimental approach. [ABSTRACT FROM AUTHOR]

A digital sensorless adaptive voltage positioning (SLAVP) control method is presented in this paper in order to realize AVP control without the need for load or inductor current sensing and high-resolution high-speed analog-to-digital converter sampling. The SLAVP control law utilizes the readily available error signal of the conventional voltage-mode closed-loop compensated controller or, in other words, the duty cycle of a dc–dc buck converter in order to realize AVP control. The elimination of the need for high-speed and accurate sensing and sampling of currents using the proposed SLAVP control reduces the size and cost of the digital controller, reduces the power losses associated with current sensing and sampling, and simplifies hardware design. Moreover, the SLAVP control can easily be added to controllers with conventional voltage-mode closed-loop control with minimum size and cost increase, and therefore, SLAVP control can be used for a wide range of applications and not only for high-end applications like powering microprocessors. The theoretical SLAVP control law derivation and analysis and SLAVP controller architecture are presented in this paper and verified by experimental results obtained from a proof-of-concept experimental prototype. [ABSTRACT FROM AUTHOR]

In this paper, a real-time walking trajectory generation method with three-mass models at constant body height for 3-D biped robots is extended for a diagonal walking. By realization of the diagonal walking, the availability is improved. The modeling of this method is more precise than that of conventional real-time walking trajectory generation methods. In this method, the zero-moment point equation of a body is derived, and an analytic solution of a body trajectory at a constant body height in a single support phase is obtained. Because the analytic solution is used, real-time trajectory generation can be realized. In addition, this method has advantages of the body trajectory at the constant body height. The validities are confirmed from simulations of the 2-D walking and an experiment of the 3-D diagonal walking. [ABSTRACT FROM AUTHOR]

It is difficult to realize a transparent bilateral control over network because communication time delay, jitter, or packet loss deteriorates transparency and stability. Although many dead time compensation methods have been considered, each approach does not realize both high transparency and stability. To solve the problem, our previous work has proposed a multirate sampling method for bilateral control systems. In this approach, packet-sending period tp is set to larger than the control period of the master/slave robot control tc. This method has an advantage to improve the transparency because large tp often reduces communication delays. However, that work has not shown the relationship between the transparency and the value of tp. Therefore, this paper analyzes the relationship between the transparency and tp by introducing frequency characteristic of an ideal sampler and a zero-order holder. In addition, the validity of the analysis is shown by experimental results. [ABSTRACT FROM AUTHOR]

Due to the high rise in luminous efficiency that high-brightness light-emitting diodes (HB-LEDs) have experienced in recent years, many new applications have been researched. This paper covers a streetlight LED application using the offline integrated buck–flyback converter (IBFC) developed in previous works. In this application, the converter is used to provide power-factor correction from a universal ac source. A control loop using the LM3524 IC has been implemented for testing the feasibility of Enabling pulsewidth modulation dimming mode. First, the LED load has been linearized and modeled in order to calculate the IBFC topology properly. Second, the converter has been designed and tested at the laboratory. The converter has also been modeled in order to design a fixed-frequency constant-current control. The dynamics of all the stages involved in the closed loop have been taken into account in order to develop an adequate controller. Finally, the experimental results obtained from the laboratory tests are discussed. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to simplify the implementation of continuous and discontinuous 3-D space vector pulsewidth modulations (SVPWMs). This paper analyzes the relationships, whether in abc or \alpha\beta 0 coordinates, between three-phase voltages and the following elements: the tetrahedron in which the reference vector resides, three adjacent active switching vectors (or three switching states), and their duration times. Based on the analysis, the calculation of the turn-on time of each switch in the actual implementation is simplified, and discontinuous PWM (DPWM) methods in three-leg inverters can be extended to four-leg inverters without the phase angle. In addition, two more DPWM methods that are peculiar to 3-D SVPWM are presented. This simplified algorithm does not use irrational operations or look-up tables, and it alleviates the computation burden of the processor. The simulation and experimental results are provided to validate the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Improving the fault ride-through (FRT) capability of doubly fed induction generators (DFIGs) in wind power applications is a very important challenge for the wind power industry. The mathematical models of such generators enable us to analyze their response under generic conditions. However, their mathematical complexity does not contribute to simplifying the analysis of the system under transient conditions and hence does not help in finding straightforward solutions for enhancing their FRT. This paper presents a simplified model of the DFIG, which has been extracted from the classical fifth-order model, which can accurately estimate the behavior of the system while significantly reducing its complexity. In this paper, the mathematical deduction of this model will be presented, and simulations and experimental results will be shown to demonstrate the accuracy and reliability of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a new multiresonant frequency-adaptive synchronization method for grid-connected power converters that allows estimating not only the positive- and negative-sequence components of the power signal at the fundamental frequency but also other sequence components at other harmonic frequencies. The proposed system is called MSOGI-FLL since it is based on both a harmonic decoupling network consisting of multiple second-order generalized integrators (MSOGIs) and a frequency-locked loop (FLL), which makes the system frequency adaptive. In this paper, the MSOGI-FLL is analyzed for single- and three-phase applications, deducing some key expressions regarding its stability and tuning. Moreover, the performance of the MSOGI-FLL is evaluated by both simulations and experiments to show its capability for detecting different harmonic components in a highly polluted grid scenario. [ABSTRACT FROM AUTHOR]

This paper deals with the optimization problem of internal structure of neural-network (NN)-based state estimators of the drive system with elastic joints. Saliency-based optimization methods, developed in the NN theory, are tested in this paper to obtain the high-quality estimation of torsional torque and load-machine speed. The optimal brain damage and optimal brain surgeon methods are compared in this application. The state variables estimated by the optimized NN are used in feedback paths in the two-mass drive structure with a state controller. The simulation results show good accuracy of both presented neural estimators for a wide range of changes of the reference speed and the load torque. The simulation results are verified by laboratory experiments. [ABSTRACT FROM AUTHOR]

This paper studies the problem of output tracking for networked control systems with network-induced delay, packet disorder, and packet dropout. The round-trip time (RTT) delay is redefined to describe these communication constraints in a unified way. By including the output tracking error as an additional state, the output tracking problem is converted into the stabilization problem of an augmented system. Based on the observer of the original state increment and the feedback of the output tracking error, a model-based networked predictive output tracking control (NPOTC) scheme is proposed to actively compensate for the random RTT delay. The closed-loop stability is proved to be independent of the RTT delay, and the separation principle for the design of the observer-based state feedback controller is still held in the NPOTC system. A two-stage controller design procedure is presented, which not only guarantees the stability of the closed-loop NPOTC system but also achieves the same output tracking performance as that of the local control system for time-varying reference signals. Both numerical simulations and practical experiments on an Internet-based servo motor system illustrate the effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

Power electronic traction transformer (PETT) is a new topology for a traction drive system, which can realize the high voltage and power conversion through multilevel converters and high-/medium-frequency transformer link. Reliability becomes a key issue for PETT adopting the module-cascaded structure. In this paper, an improved fault-tolerant method based on reverse-charging control of dual active bridge is proposed, which is suitable for PETT and other two-stage structure converters. The control strategy and operating process of an improved fault-tolerant method are introduced. Comparisons among improved and traditional fault-tolerant methods are also presented. Simulation and experimental results are provided to show the correctness and effectiveness of the improved fault-tolerant method. [ABSTRACT FROM PUBLISHER]

This paper presents a comparative evaluation of eight high-voltage step-up converters based on different associations of boost and zeta standard dc–dc pulse width modulation (PWM) cells. These eight converters present different characteristics such as cascaded and stacked PWM cell associations, as well as isolated winding coupled inductors, tapped winding coupled inductors, and noncoupled inductors. In order to explore the advantages and address the limitations of each topology, several comparative evaluations concerning static voltage gain, power losses, current and voltage stresses, component stress factors, power density, relative cost, and efficiency were carried out. From the theoretical analysis and experimental results, the association named stacked boost–zeta with autotransformer yielded the highest efficiency and power density and resulted in the most attractive converter for the case study. [ABSTRACT FROM PUBLISHER]

Two main problems, including unbalanced grid input and circuit parameters uncertainty in the three-phase soft-switching converter control system, are considered in this paper. First, the constant-switching-frequency model-predictive control (CF-MPC) is improved for application in compound active-clamp zero-voltage-switching three-phase power factor correction converter. Second, a robust-constant-frequency model-predictive control (RCF-MPC) method is proposed for current loop; the novel contributions are: 1) the negative-sequence current component is introduced into the cost function of the model-predictive control to decrease the influence of unbalanced grid input; and 2) a robust item is added into the predictive model to reduce the influence of the circuit parameter uncertainty. Third, a robust variable structure controller is proposed for voltage loop considering the capacitor and load uncertainty. The simulation and experiment results show that, compared with the original CF-MPC method and the traditional proportional–integral control method, the proposed RCF-MPC method decreases the total harmonic distortion under the unbalanced grid condition. Meanwhile, the voltage loop robust variable structure controller has better transient and steady-state performance with respect to the load perturbation. [ABSTRACT FROM PUBLISHER]

Microinverters for photovoltaic (PV) modules can improve the energy generation by reducing the effects of shading, since the energy harvesting of each PV module can be controlled individually. In this context, this paper presents a topology of single-stage transformerless grid-connected boost microinverter. It promotes high voltage gain without using a preregulator circuit or a high/low-frequency transformer. A 500 W laboratory prototype was implemented and experimental tests were carried out so that the proposed microinverter was evaluated in a grid-connected PV system. Experimental analysis was performed in order to corroborate the theoretical approach and to verify the effectiveness of the proposed modified Perturb and Observe “Gama” maximum power point tracking technique and the proportional-resonant (P-Res) grid current controller under different irradiation conditions and under partial shading. [ABSTRACT FROM PUBLISHER]

In this paper, a novel nonconventional angle displacement (i.e., 15°) between two sets of three-phase windings is proposed for dual three-phase permanent-magnet (PM) machines. First, all feasible angle displacements between the two three-phase winding sets for various slot/pole number combinations of dual three-phase machines are discussed in general. Then, an in-depth investigation is carried out on a 24-slot/10-pole dual three-phase PM machine as an example covering various electromagnetic performances. The investigation shows that under healthy and three-phase open-circuit conditions, the proposed 15° configuration has a comparable electromagnetic performance to the 30° configuration, and a better performance than the 0° counterpart. Furthermore, under three-phase short-circuit (SC) condition, the proposed 15° configuration has the lowest SC current, smallest braking torque, and the best PM demagnetization withstand capability. Finally, three prototype 24-slot/10-pole surface-mounted PM machines are built and tested to verify the theoretical analyses. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to explore the capability of a charge trapping control loop to continuously compensate charge induced by ionizing radiation in the dielectric of metal–oxide–semiconductor (MOS) capacitors. To this effect, two devices made with silicon oxide have been simultaneously irradiated with gamma radiation: one with constant voltage bias and the other working under a dielectric charge control. The experiment shows substantial charge trapping in the uncontrolled device, whereas, at the same time, the control loop is able to compensate the charge induced by gamma radiation in the second device. [ABSTRACT FROM PUBLISHER]

In high-voltage output applications, the rectifier diodes in the conventional full-bridge converter have to bear the whole secondary voltage of a transformer. In this paper, a three-level rectifier structure with flying capacitors is proposed for the dc–dc converter. Compared with the conventional dc–dc converter, the converter with the proposed rectifier structure has the following advantages: low-voltage diodes could be used for high-voltage output applications; due to the secondary flying capacitors, there are no voltage spikes on the rectifier diodes even if no snubber circuits are attached; not only can the leading switches realize zero voltage switching (ZVS) as the same as the conventional converters, but also the lagging switches can realize zero current switching in discontinuous-conduction mode and ZVS in continuous-conduction mode; and the rectified voltage has no zero-state voltage, it has been raised to half of the input voltage, so the voltage fluctuation is lower than the conventional converter under the same modulation strategy, and the current ripple of the filter inductor can be reduced by half. The operation principle of the proposed rectifier structure is analyzed in details, and a prototype is fabricated to verify the features of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper proposes an improved offset selection method for discontinuous-pulse-width-modulation (DPWM)-based back-to-back converters to reduce dc-link current ripple. DPWM is introduced to power converters to diminish the stress on power transistors and prolong their lifespan. However, when using the DPWM method, the dc-link current ripple is increased in nonswitching regions of the power transistors. Moreover, in DPWM-based back-to-back converters, the dc-link current ripple reaches its maximum when the two transistors of both inverters are clamped in opposite directions. Therefore, the dc-link capacitors endure more stress, resulting in decreased life duration. To overcome this issue, the switching method should consider the clamping periods, when the current ripple increases. This can be achieved by modifying the DPWM offset, so that the clamping states of both converters are matched. The effectiveness of the proposed method is confirmed by both simulation and experimental results. [ABSTRACT FROM PUBLISHER]

The problem of determining an interaction control strategy, allowing a manipulator to reach a goal point even in the presence of unknown obstacles, is faced in this paper. To this end, on the basis of position/orientation and force measurements, first, a path planning strategy is proposed. The path planning is based on an a priori trajectory, which is determined without the prior knowledge of the obstacle presence in the workspace, and on a real-time approach to generate auxiliary temporary trajectories on the basis of the properties of the obstacle surface in a vicinity of the contact point, estimated through force measurements. To determine the input laws of the manipulator, a robust hybrid position/force control scheme is adopted. First- and second-order sliding mode controllers are considered to generate the robot input laws, and the obtained performances are experimentally compared with those of classical PD control. Experiments are made on a COMAU SMART3-S2 anthropomorphic industrial manipulator. [ABSTRACT FROM PUBLISHER]

This paper aims at analyzing the effect of widely known impedance-shaping (IS) control method on the perception of soft tissues in telemicrosurgical applications. The generalized teleoperation control architecture has been modified to include the IS term. New performance index has been defined based on the two proposed indices for the detection and the discrimination of the soft environments to analyze the effect of this modified control on the kinesthetic perception of soft tissues. The effect is then theoretically analyzed on the conventional position–position, force–position, and four-channel control architectures based on the newly defined index. The effectiveness of this newly proposed kinesthetic perception index is also verified using psychophysics experiments. The theoretical analysis of the effects of the IS method on the perception of soft tissues is then validated using the proposed index by experiments with phantom soft tissues for conventional teleoperation architectures. [ABSTRACT FROM PUBLISHER]

This paper proposes a generalized equivalent magnetic circuit model for the design of permanent-magnet (PM) electric machines. Conventional approaches have been applied to PM machine design but may be insufficiently accurate or generalized without taking pole–slot counts into consideration. This would result in reduction of dimensioning accuracy at the initial design stage. Also, magnetic saturation is often ignored or compensated by correction factors in simplified models since it is difficult to determine the flux in individual stator teeth. In this paper, the flux produced by stator winding currents and PMs can be calculated accurately and rapidly using the developed model, taking saturation into account. A new modeling technique for PM poles is proposed so that the magnetic circuit is applicable to any pole–slot combinations. This aids machine dimensioning without the need for computationally expensive finite-element analysis (FEA). A 540-kW PM machine is first designed using the proposed method and then verified with FEA. Another 350-W machine is subsequently designed, manufactured, and validated by both FEA and experiments. The comparisons demonstrate the effectiveness of the proposed model. [ABSTRACT FROM PUBLISHER]

This paper presents a comparative study between field-oriented control (FOC) and Predictive Torque Control (PTC) applied to induction machines. Both strategies are implemented on the same experimental bench and similar tests are performed. Furthermore, they were previously adjusted to get an equivalent switching frequency at a specific operation point, achieving the fairest possible comparison at steady state. Experimental results verify that PTC can achieve results similar to FOC, possibly even improving performance in transient conditions. [ABSTRACT FROM PUBLISHER]

This paper presents a new configuration for switched reluctance motor (SRM) which can be proposed as a suitable candidate for high-torque and low-flux-leakage SRMs. Unlike the conventional SRMs, this configuration has no direct windings wrapped on the stator poles. This motor consists of three different sets, and each set has one concentric independent winding, two layers of the stator poles, and three layers of the rotor poles in which the middle rotor layer acts as a core for phase winding. To evaluate the motor performance, two types of analysis, namely, numerical technique and experimental study, have been utilized. In the numerical analysis, the 3-D finite-element method is employed, whereas in the experimental study, a prototype motor has been fabricated and tested in the laboratory. Finally, experimental results are compared to conventional SRM to verify the advantages of the proposed motor and show its applicability. [ABSTRACT FROM PUBLISHER]

This paper presents the three-phase version of the isolated dc–dc Weinberg converter. The main characteristics of the proposed converter are as follows: small volume, low weight, reduced number of components, buck operation for a duty cycle of less than 1/3, and input and output current ripple cancellation for a duty cycle of 1/3 or 2/3. Typical applications include telecommunication, electric vehicles, renewable energy conversion systems, and batteries. This paper gives theoretical analysis, design example, and experimental data on a 735-W 120-Vdc-input 75-Vdc-output 42-kHz switching frequency laboratory prototype. The prototype performance shows good agreement with the theoretical predictions. [ABSTRACT FROM PUBLISHER]

In this paper, a rectangular contactless transformer is proposed to be used in a contactless power supply system. The proposed rectangular contactless transformer maintains a high coupling coefficient even when it has a relatively large air gap. The characteristics of the proposed transformer are compared to a transformer using a general EE core with a variable air gap. The proposed system is verified through simulation and experimental results. The experimental results demonstrate that the efficiency of the contactless power transmission system using a contactless transformer based on a rectangular core is over 20% greater than the system based on the EE core. [ABSTRACT FROM AUTHOR]

The power efficiency degradation of machines often provides intrinsic indication of problems associated with their operation health conditions. Inspired by this observation, as presented in this paper, a simple yet effective power efficiency estimation-based health monitoring and fault detection technique is developed for a modular and reconfigurable robot (MRR) with a joint torque sensor. Power efficiency coefficients of each joint module are obtained using sensor measurements and used directly for health monitoring and fault detection. The proposed method has been experimentally tested on an MRR that has been developed in our laboratory for working in human environments, which critically demands for efficient health monitoring and fault detection capabilities. Experimental results have demonstrated the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a new standby structure where the standby flyback converter is integrated with the zero-voltage-switching multi-output full-bridge dc–dc converter. While the standby power is generated from the conventional flyback converter in standby mode, the auxiliary output of the multi-output full-bridge converter is used for the standby output in normal mode. The validity of this proposed structure is confirmed by the experimental results from 12 V/58 A for the dc–dc output and 5 V/3.2 A for the standby output prototype. [ABSTRACT FROM AUTHOR]

This paper presents a controller-design methodology for a class of underactuated mechanical systems that are affected by parametric uncertainties and external disturbances. The perturbations due to parametric uncertainties are mismatched, whereas those caused by external disturbances are of the matched type. Their effects are canceled by employing a novel strategy that combines time scaling and Lyapunov redesign. The control methodology is applied to a two-wheeled mobile inverted pendulum and a ball–beam system. Along the way, the nonexistence of a smooth control law for point-to-point stabilization of the mobile inverted pendulum is established. Simulation and experimental studies are used to verify the efficacy of the proposed controller-design method. [ABSTRACT FROM AUTHOR]

This paper presents a novel multilevel active-clamped converter topology, which is an extension to m levels of the three-level active neutral-point-clamped topology. The operating principle is established through the definition of a proper set of switching states and a transition strategy between adjacent switching states. The benefits of the proposed converter topology and control in comparison to alternative multilevel converter topologies are discussed. The simulation and experimental results of a simple four-level dc–dc converter configuration are presented to illustrate the converter performance features. The experimental results of a four-level three-phase dc–ac converter are also presented to further validate the proposed topology and operating principle. [ABSTRACT FROM AUTHOR]

Toroidally wound brushless dc (BLDC) machines are compact, economical, and can operate across large air gaps. In this paper, we provide analytical design equations for a radial-flux toroidally wound BLDC machine. The validity of the design equations is checked against finite-element analyses (FEAs) and experiments. It is found that the motor constant calculated by the design equations is off only by 5% from the results by the FEAs or experiments. We also provide an optimization metric that corresponds to the maximization of machine torque while maintaining minimum power loss. Two optimal design cases are presented. [ABSTRACT FROM AUTHOR]

This paper presents the design and experimental results of the robust attitude regulation for a 3-DOF Quanser helicopter benchmark. The control objective is to asymptotically track the desired elevation and pitch reference signals generated by an exogenous system, while keeping all the closed-loop states bounded, even if there exist unknown uncertainties. Based on the output-regulation theory and signal compensation technique, a new design method of state feedback robust controller is proposed. This method permits the existence of unknown uncertainties and external disturbances in both the helicopter and the exosystem. Only knowledge about the bounds of these uncertainties is required. The experimental results demonstrate the desired performance of the proposed controller implemented on the Quanser helicopter. [ABSTRACT FROM AUTHOR]

This paper presents fault-tolerant control techniques for five-phase permanent-magnet motors with trapezoidal back electromotive forces under various open-circuit conditions. The proposed fault-tolerant control methods use only the fundamental and third-harmonic current components for the excitation of the healthy stator phases. The control techniques are developed by applying a concept that correlates the currents in the healthy phases based on their symmetry in space with respect to the fault in a machine. Optimum solutions under the single-phase open-circuit fault condition and double-phase open-circuit fault conditions are presented. The presented solutions are derived to increase the average output torque while reducing the torque pulsations and satisfying the zero-neutral-current constraint. Detailed experimental results are presented for the verification of the proposed solutions. [ABSTRACT FROM AUTHOR]

In this paper, sliding-mode control is applied on multi-input/multi-output (MIMO) nonlinear systems. A novel approach is proposed, which allows chattering reduction on control input while keeping high tracking performance of the controller in steady-state regime. This approach consists of designing a nonlinear reaching law by using an exponential function that dynamically adapts to the variations of the controlled system. Experimental study was focused on a MIMO modular robot arm. Experimental results are presented to show the effectiveness of the proposed approach, regarding particularly the chattering reduction on control input in steady-state regime. [ABSTRACT FROM AUTHOR]

Constant power loads (CPLs) are very common in multiconverter power system applications. Buck converters loaded by CPLs have different start-up and step-response processes from the resistive load. This paper analyzes the start-up process and step response of an average current-controlled buck converter with CPLs based on the phase portrait method. Design criteria rules have been proposed to achieve system stability during start-up and load transient processes. The proper current-limiting value is proposed accordingly to avoid the instability during the start-up and load change dynamics. Simulation and experimental results verify the analysis and the proposed proper current-limit value. [ABSTRACT FROM AUTHOR]