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This paper describes a strategy of backward motion control in a tractor-trailer system. The backward motion of a tractor-trailer requires skilled control, because the position and orientation of the trailer can only be controlled by an input to the tractor. When a driver changes orientation while driving backward, the steering angle must be skillfully controlled. This operation is different in the case of a single vehicle moving backward. An uncontrollable situation of a tractor-trailer motion often happens, for example, the "jackknife phenomenon." Such a situation is often induced by the nonholonomic constraint of a wheeled system. In this research, virtual steering is introduced to a trailer. This virtual steering controls the orientation of the trailer and suppresses the nonholonomic equivalent disturbance. With this virtual steering, the tractor-trailer is able to track a straight trajectory in backward driving independently of the nonholonomic constraint. Several numerical and experimental results are shown to confirm the validity of the proposed approach.

In this paper a novel Radial-Axial (RA) Flux Switching Permanent Magnet Generator (FSPMG) is introduced. In contrast to other RA flux machines, a major advantage of this generator is its implementation only by the use of conventional Non-Oriented Electrical Steel Sheets (NOESSs), even though the flux linkage of the novel RA-FSPMG has a three-dimensional (3D) path. Besides that, it benefits from the flux concentration strategy and a passive rotor. A concrete foundation of the novel RA-FSPMG is provided, in which, the 3D-Flux path is described, working principles are discussed, and power-sizing equation is derived. No-load (NL) characteristics and the Full Load (FL) performance of an optimized RA-FSPMG are investigated in contrast to an optimized Double Stator Radial (DSR) FSPMG and an optimized Double Stator Axial (DSA) FSPMG with similar volume, number of Permanent Magnets (PMs), and electrical loading. The results show the competitiveness of the novel RA-FSPMG, in particular, in the output power and the required copper mass. Furthermore, the PM demagnetization possibility and the rotor axial pull force of the optimized RA-FSPMG are investigated, in detail. All discussions are supported by the 3D Finite Element Analysis (3D-FEA) and experimental results.

This paper proposes and implements a new method for the estimation of the battery residual capacity (BRC) for electric vehicles (EVs). The key of the proposed method is to model the EV battery by using the adaptive neuro-fuzzy inference system. Different operating profiles of the EV battery are investigated including the constant current discharge and the random current discharge as well as the standard EV driving cycles in Europe, the US, and Japan. The estimated BRCs are directly compared with the actual BRCs, verifying the accuracy and effectiveness of the proposed modeling method. Moreover, this method can be easily implemented by a low-cost microcontroller and can readily be extended to the estimation of the BRC for other types of EV batteries.

The optimization of Litz-wire gapped-core high-frequency transformer (LGHT) for LLC-converters is a challenging task owing to application requirements and complex relationship between multiple design-objectives and constraints. This necessitates the use of multi-objective optimization-techniques to obtain trade-off design-solutions; however, these are cumbersome methods that require many iterations and resources. Therefore, this paper proposes an improved and efficient Pareto-optimization method for LGHT-design. It combines multi-objective whale-optimization algorithm (MOWOA) and analytical core-geometry factor model (OKGM)-based core and winding selection method while keeping in consideration the LLC-converter requirements. The proposed method utilizes benefits of both method-types; it obtains the best LGHT-design in shortest-time and minimum-iterations with optimized volume and losses, integrated magnetizing-inductance, and satisfied thermal-limit. The method is made resource-efficient by carefully selecting independent and necessary LGHT design-parameters as optimization variables keeping in view interdependency among the parameters and LLC-converter performance; these include peak-flux-density, LGHT design-frequency, core-window utilization-factor, core-material, and core-shape. For best design-selection, supplementary decision functions (total-loss and loss-&-volume-product) are used together with the objective functions (core-loss, winding-loss, and total-volume) to enhance the optimal Pareto-solutions diversity and to assist designers in decision-making. The method is proven via comparison with existing benchmark-methods and validated through performance demonstration of LHGT-prototype in 400VDC-to-12VDC LLC-converter.

This paper investigates a problem of stabilization control design. A novel triggering mechanism, called parallel-triggering mechanism, is proposed to handle the stabilization of nonlinear/linear systems. Compared with the existing triggering conditions, through fully considering the relationship between the variation of the Lyapunov function and the variation of system states, we propose the parallel-triggering mechanism, without the requirement that the derivative of the Lyapunov function is negative at all-time instants. Under the new parallel-triggering mechanism, the number of executions of control tasks can be significantly reduced and the similar stability performance can be kept. Particularly, the existing event-triggered conditions can be seen as special cases of the proposed parallel-triggering mechanism. Theoretical analysis and simulation results are given to show the advantages of the proposed mechanism in this paper.

Steel wire rope (SWR) can be frequently damaged by various factors. Although weak defect signal detection is the key to guarantee safety, current classic stochastic resonance (SR) models and methods are unavailable due to the complicated interference of noise. Thus, a novel E-exponential SR model and weak signal detection method are proposed in this paper. The principle of this model is first introduced from the perspective of Taylor expansion and nonlinear system analysis. Then, the model performance is simulated and evaluated by output signal analysis and chaos characterizations. Afterwards, model comparison with different system parameters, experiments and case studies regarding three typical wire rope defects inspection and weak signal recognition are conducted to demonstrate the validity of the novel method. Finally, the advantages and limitations of the proposed SR model are discussed.

Parallel operation of two 6-n prepulse uncontrolled bridge rectifiers, to obtain a 12-pulse rectification, without an interphase transformer connected on the DC sides is investigated in this paper. The mechanism of interactions between the two six-pulse bridges is analyzed. As the load current varies from no-load to the complete short-circuit value, seven modes of operation are recognized. Equations describing the mean output voltage and various operating angles of the rectifier circuit are given in terms of a reactance factor. Voltage regulation and variations of the ignition angle and the commutation overlap angle for rectifiers with and without an interphase transformer are also compared.

High-frequency iron losses caused by the variations of sinusoidal flux density with frequencies ranging from 2.5 kHz to 40 kHz, amplitudes from 1mT to 70mT, and dc-biased magnetic inductions from 0 to 1.62T are measured with the dual-transformer system. Then, a simple frequency-domain model is proposed based on linear fitting and 2D interpolation methods for engineering applications. In addition, another two frequency-domain models respectively considering and neglecting excess losses are investigated and compared for the high-frequency iron loss modeling, which only need low-frequency parameters and contain physical interpretation to the variation of high-frequency iron loss coefficients with frequency, AC flux density amplitude, and dc-biased magnetic induction. The iron losses generated by unipolar and bipolar PWM voltages with different switching frequencies and modulation factors are measured to testify the three models. It is shown that the three models in this paper are more accurate than the previously proposed one for calculating the PWM-induced iron loss by considering the variation of model parameters with dc-biased magnetic induction and AC flux density amplitude, especially when silicon steel sheets reach saturation.

The flying capacitor multilevel inverter (FCMLI) is one of the well-known structures of multilevel inverters having attracted considerable attention because of its merits. In spite of its many advantages, it has some limitations such as high volume and complicated control method because of its bulky capacitors and their voltage balancing requirement. Moreover, the high number of power semiconductors required makes this structure susceptible to failure. To increase the ratio of the number of levels to the number of components, an uneven distribution of capacitor voltages has been suggested in previous reports; however, this approach complicates the control method. Up to now, almost all presented methods suffer from high computational load and/or structure-dependent algorithm. In this paper, a simple state-based and structure-independent method is proposed for capacitor voltage regulation. The proposed method is straightforward and can perform online computation of switching sequences in a computationally efficient manner without any need for stored information or look-up tables. The method is conveniently extendible to any number of cells and levels in an FCMLI structure with arbitrary dc link voltage distribution schemes. Simulation and experimental results show the effectiveness and simplicity of this method.

Litz wires are employed in high-frequency electrical machines due to their advantages of reducing the ac losses, including minimizing the skin effect and the proximity effect. In order to improve the reliability of such machines, and enable accurate thermal predictions at the design stage, accurate calculation of the thermal conductivity of litz wire is important. In this paper, a calculation method based on the Gasar porous metal materials model is put forward. In this method, a cell model is extracted from the litz wire, and a thermal resistance network is used to calculate the equivalent thermal conductivity (ETC). Following this, two finite-element analysis (FEA) models for the same litz wire are built, one with actual thermal conductivities for the different constituent materials and another with the calculated equivalent thermal conductivity for an equivalent material, with the two models showing similar thermal characteristics. Finally, an experimental setup is built for measuring the steady-state ETC of litz wire. The apparatus structure and characteristics are described in detail, and the experiment uncertainty and measurement errors are analyzed. Three types of litz wire are measured in the experimental, and the results from experiment and calculation are consistent.

This paper presents a new highly integrable hybrid step-down converter that merges switched-inductor and switched-capacitor operations and significantly reduces onboard loss by using the input cable's parasitic inductance as its main inductor. This converter has the inductor placed at the input with a smaller voltage swing, leading to possible use of a smaller inductor and low-voltage rating switches that generally translate to reduced conduction losses. Analyses of converter operation and losses to reveal its original characteristics and design guidelines are presented to facilitate the components optimization. The converter architecture is verified by a proof-of-concept 15-W inductor-less lithium-ion battery charger prototype that uses a 1-m USB 3.0 cable as inductor. The converter, switched at 2 MHz from a 5-V input, experimentally achieves 89.7% peak efficiency and 6% higher efficiency at full load than a Buck converter counterpart. This high efficiency and zero onboard inductor yield a relative 45.7% onboard loss reduction at full load, promising excellent integration feasibility and superior system thermal management.

This paper presents a design, simulation, and evaluation procedure of a variable inductor (VI) for a recently proposed dc-grid LED driver. The design procedure is based on the use of SPICE behavioral modeling to implement the different elements of the equivalent reluctance model of the VI. Thus, the model merges both electrical and magnetic behavior of the VI, including magnetic and geometric features. The basic components of the model are presented in detail, making it possible their use in future designs of VI and other complex magnetic devices. Experimental results from both VI and LED driver prototypes are provided to compare with the simulation results. Obtained outcomes prove that the proposed design and modeling technique is an excellent way to verify theoretical designs and attain further insight about the operation of these complex magnetic devices.

This paper develops a novel integral sliding mode controller (ISMC) for a general type of underwater robots based on multiple-input and multiple-output extended-state-observer (MIMO-ESO). The difficulties associated with the unmeasured velocities, unknown disturbances, and uncertain hydrodynamics of the robot have been successfully solved in the control design. An adaptive MIMO-ESO is designed not only to estimate the unmeasurable linear and angular velocities, but also to estimate the unknown external disturbances. An ISMC is then designed using Lyapunov synthesis, and an adaptive gain update algorithm is introduced to estimate the upper bound of the uncertainties. Rigorous theoretical analysis is performed to show that the proposed control method is able to achieve asymptotical tracking performance for the underwater robot. Experimental studies are also carried out to validate the effectiveness of the proposed control, and to show that the proposed approach performs better than a conventional potential difference (PD) control approach.

It is known that, for a gimbaled inertial measurement unit employing two dry-tuned gyros, a dual gyro wheel supply (DGWS) gives a better performance than a single gyro wheel supply (SGWS). The effectiveness of the DGWS is explained in this paper by demonstrating the effects of certain vibrations on gyros. It will be shown that a dry-tuned gyro is susceptible to vibrations at frequencies which are either equal to or twice that of the gyro spin frequency. By using two power supplies of slightly different frequencies, external vibrations at these frequencies are avoided. It is recommended that gyro sensitivities with respect to external vibrations at these special frequencies be included in the performance specification of a dry-tuned gyro.

The excitation system plays a critical role in the operation of synchronous generators. An equipment failure could impact the voltage quality for smaller grids. Furthermore, it can lead to cost penalties and reduced production for the power plant owner. Recently, a new high-speed-response rotating brushless exciter was developed that employs remote control of the rotating thyristors on the generator shaft. This has led to new possibilities for improving the performance of brushless exciters. This contribution investigates the failure modes of a dual-star outer pole exciter that feeds two separate thyristor bridges connected in parallel during a normal operation. The possibility of a redundant postfault operation due to open-thyristor or open-phase faults is demonstrated using experimental testing. The system is compared with the fault performance of a conventional three-phase system. This paper includes the implementation and validation of a fault-predicting double d–q exciter model. In addition, the dangerous effects of a shorted-thyristor fault are investigated. A “skip firing” protection technique is briefly demonstrated for the fast isolation of such faults, yielding nondestructive postfault recovery and redundant failure-mode operation. The evidence shows that the dual-star exciter is a competitive choice for the future development of fault-tolerant brushless exciters.

Notice of Violation of IEEE Publication Principles "Performance Improvement of a Line-Start Permanent-Magnet Synchronous Motor" by Solmaz Kahourzade, Amin Mahmoudi and Wooi Ping Hew, in the IEEE Transactions on Industrial Electronics After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE's Publication Principles. This paper was submitted with significant similarity to ideas and applications presented in the thesis listed below. The paper includes a reference to the thesis, but there was no clear delineation between their work and previous work presented in the thesis. Two of the authors, Solmaz Kahourzade and Amin Mahmoudi were found to be responsible for the misconduct. "Line Start Permanent Magnet Motors," by Arash Hassanpour Isfahani, in Ph.D dissertation, Department of Electrical Engineering, Tehran University, Iran, 2011. This paper presents the design and performance analysis of a line-start permanent-magnet synchronous motor to overcome the efficiency and power factor deficiencies of induction motors. Proper start-up and synchronization are considered. An optimization algorithm is applied to improve the rotor bar resistance for the smooth line start of the motor. Dynamic d-q modeling and finite element analysis are performed to predict the transient and steady-state performances of the motor. Based on the presented optimized design, a 3-phase, 4-pole, 2 kW line-start permanent-magnet synchronous motor is fabricated and tested. Simulation and experimental results validate the improved performance of the proposed optimized motor.

Notice of Violation of IEEE Publication Principles "A Hybrid ANFIS/ABC-based Online Selective Harmonic Elimination Switching Pattern for Cascaded Multi-level Inverters of Microgrids," by H. R. Baghaee; M. Mirsalim; G. B. Gharehpetian; H. A. Talebi; A. Niknam-Kumle, in the IEEE Transactions on Industrial Electronics After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. This authorship of this paper was revised without providing attribution to, or permission from, the coauthors of an earlier version of the manuscript. Alireza Niknam-Kumle was responsible for removing the original coauthor names and replacing them with new coauthors, and then resubmitting the content in a new manuscript to IEEE Transactions on Industrial Electronics Due to the nature of this violation, reasonable effort should be made to remove all past and future references to this paper. Control of electronically-coupled distributed energy resources and topology/switching strategy of power converters have the essential roles to provide high quality power for microgrids including unbalanced and nonlinear loads. Multi-level inverters (MLIs) are used to act as high quality converters with more conversion efficiency, and less switching-frequency/switching-losses. Nevertheless their nonlinearity, complexity, and solvability features of selective harmonic elimination strategy that has affected its industrial applications, it can provide desirable output waveform by keeping fundamental component in its desired value as well as eliminating/minimizing of low-order harmonics. This paper presents adaptive neuro-fuzzy inference system (ANFIS) as a switching angle estimator for harmonic optimization problem in cascade MLIs, which is trained based on the database including optimal switching angles obtained for inverter with non-equal DC sources by artificial bee colony (ABC) algorithm. The reliable search ability, accuracy and convergence time of ABC have been compared with particle swarm optimization algorithm. Also, performance of ANFIS is compared with artificial neural network based on correlation coefficient and root mean square error. Simulation results, experimental tests and real-time simulations reveals the effectiveness of proposed estimator for online elimination of low-order harmonics of MLIs in microgrids and its superiority over other methods.

Notice of Violation of IEEE Publication Principles "Integrated Control of Braking and Steering Subsystems for Autonomous Vehicle based on an Efficient Yaw Moment Distribution" by Shaobo Lu, Sheng Cen, Xiaosong Hu, Cheewah Lim and Jinlong Zhang, in the IEEE Transactions on Industrial Electronics, Early Access, May 2017 After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. This paper copies equations from the paper(s) cited below. The content was copied without attribution (including appropriate references to the original author(s) and/or paper title) and without permission. The lead and the second author of the paper were responsible for the violation. A correction letter for this misconduct was submitted and published at http://ieeexplore.ieee.org/document/8017449 "Coordinated Control with Electronic Stability Control and Active Front Steering Using the Optimum Yaw Moment Distribution Under a Lateral Force Constraint on the Active Front Steering" by Seongjin Yim, Seungjun Kim and Heesung Yun, in the Proceedings of Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2016, Vol. 230(5) pp. 581-592 This paper presents an Integrated Chassis Control (ICC) strategy for Electronic Stability Control (ESC) and Active Four Wheel Steering (AFWS) based on an efficient optimal yaw moment distribution. To further enhance the handling and lateral stability of vehicle equipped with ESC, a new Weighted Pseudo- inverse Control Allocation (WPCA) based ICC is proposed. The cornering forces of both front and rear wheels are used to cooperate with the ESC braking forces, so as to further extend the operational envelope of the vehicle. A bi-level hierarchical control structure is employed. In the upper level, the sliding mode control with a combined sliding surface is used to generate the desired virtual control. In the lower level, a revised optimal function is defined to tune the control authority of actuators, and an algebraic operation based WPCA method is adopted. To avoid tire forces saturation and enforce a certain stability margin, a boundary layer constraint is further considered in the proposed optimization problem. A severe lane change maneuver is used to investigate the performance via closed-loop driver-vehicle- controller simulations using CarSim and MATLAB/Simulink. Simulation results demonstrate that the proposed algorithm outperforms current control practice without violating the actuators physical limitation.

This paper presents a new self-sensing actuation (SSA) circuit for using the piezoelectric (PZT) micro-actuator as both an actuator and a sensor simultaneously. The proposed SSA circuit senses the voltage signal generated by the PZT micro-actuator at operating frequencies, while the control voltage applied to the same PZT micro-actuator is not affected. The components of the proposed SSA circuit are minimized to allow easy balancing and implementation. In simulations, the proposed SSA circuit had similar characteristics to the conventional SSA circuit. In experiments, the proposed SSA circuit was tested with a commercial hard disk drive (HDD). The results show that the proposed SSA circuit does not affect the conventional read/write (R/W) head positioning control system. The frequency response of the PZT micro-actuator measured by the proposed SSA circuit had similar to the frequency response of the R/W head displacement at both the resonant frequency and the operating frequencies. The proposed SSA circuit was also tested at various operating temperatures of the HDD. Errors in the sensing voltage signal caused by the unbalanced SSA circuit clearly correlated to the temperatures from 10 °C to 60 °C.

The low core losses and high yield strength of amorphous materials are attractive properties for ultra-high-speed rotor applications. This paper proposes an innovative interior permanent-magnet synchronous rotor for ultra-high-speed motors, which takes full advantage of those properties and eliminates the need for sleeves. In order to study the feasibility of the proposed rotor, the electromagnetic properties of the amorphous core are first measured and the challenges for producing such rotors are subsequently discussed. Then, by using numerical methods, the electromagnetic, mechanical, and thermal performances of an example motor with an amorphous rotor core are evaluated and compared to those of a motor with a silicon steel rotor core. Through experimental characterization of the material and multiphysics numerical modeling of an example motor, it is shown that the amorphous material has great potential for producing high power density ultra-high-speed motors.

In multi-terminal dc networks or future dc grids, there is an important role for high step-ratio dc-dc conversion to interface a high voltage network to lower voltage infeeds or offtakes. The efficiency and controllability of dc-dc conversion will be expected to be similar to modular multi-level ac-dc converters. This paper presents a modular multilevel dc-dc converter with a high step-ratio for medium voltage and high voltage applications. Its topology on high-voltage side is derived from the half-bridge single-phase inverter with stacks of sub-modules replacing each of the switch positions. A near-square-wave current operation is proposed which achieves near-constant instantaneous power for single-phase conversion, leading to reduced stack capacitor and filter volume and also increased the power device utilization. A controller for energy balancing and current tracking is designed. The soft-switching operation on the low-voltage side is demonstrated. The high step-ratio is accomplished by combination of inherent half-bridge ratio, sub-module stack modulation and transformer turns-ratio, which also offers flexibility to satisfy wide-range conversion requirement. The theoretical analysis of this converter is verified by simulation of a full-scale 40MW, 200 kV converter with 146 sub-modules and also through experimental testing of a down-scaled prototype at 4.5 kW, 1.5 kV with 18 sub-modules.

This paper employs the recently developed nonlinear control tools to solve the engineering problem of stable current control of fused magnesium furnaces (FMFs). By fully taking into account the nonlinearity, uncertainty, and couplings in FMFs, this paper first develops a dynamic model for controller design. A mild assumption for controller design is verified by using experimental data. Based on the dynamic model, this paper proposes a class of stable control rules for the disturbance-free model. Then, the result is extended to handle both measurement errors and external disturbances. With the proposed control algorithm, it is proved that the closed-loop system is robustly stable, and the three-phase currents ultimately converge to neighborhoods of the setpoints. If the system is disturbance-free, then asymptotic stability can be guaranteed. It is shown that the proposed control algorithm can be readily implemented as rule-based control. The notion of input-to-state stability and the nonlinear small-gain theorem are employed as tools for the designs. An industrial application is demonstrated to show the validity of the proposed design in solving practical engineering problems.

A magnetic screw is a new type of high force density linear actuator. One of the key challenges for realization of the magnetic screw concept is the manufacturing process of its helical permanent-magnet (PM) poles. Structure simplification and simple assembly process are essential in promoting the development of the magnetic screw. This paper studies several PM configurations employed to realize the magnetic screw and proposes a new structure, which can well approximate the helical magnetic poles in a very simple way. The electromagnetic performances are assessed analytically and by time-stepping finite-element analysis (FEA). Finally, both the analytical model and the FE results are validated by experiments based on a prototype machine.

Almost all flux switching permanent magnet linear generators (FSPMLGs) and Vernier hybrid machines contain a heavy solid translator due to their design limitations for electricity generation from the oceanic waves. This paper presents the new design of an FSPMLG in which the translator weight is reduced and an additional static steel core is inserted inside the translator cavity to improve the magnetic flux linkage of the main stator. The generated voltage, current, power, efficiency, core loss, force ripples, and cogging force minimization of the proposed FSPMLG are presented. From the dynamic model of the oceanic wave, it is shown that the translator with lower mass could generate electricity more effectively. The special stator and translator sets have been optimized by using the genetic algorithm before they are used in the proposed FSPMLG. To analyze the performance and verify the feasibility of the new design of FSPMLG, finite element analysis is performed by using the commercial software package ANSYS/Ansoft.

The recycled batteries can be assumed for the cost-effective grid energy storage (ES) applications, where the state of health (SOH) of recycled batteries are hard to make equal when reassembling them in one ES system. Therefore, when implementing the traditional state-of-charge balancing control methods, the batteries integrated into the same ES system will demonstrate the SOH deviation characteristics during the long-term operation due to the different degradation they suffered, which will reduce the mean time to repair, increase the maintenance duty, and shorten the life time of the ES system. Alternatively, this paper proposes an SOH balancing control method for the modular multilevel-converter-based battery energy storage system (MMC BESS) by fully using the unique modular configuration. The relationship among SOH, depth of discharge, and life cycles is analyzed in the theory, which builds the criteria for power distribution among battery packs in the MMC BESS. In addition, instead of estimating the specific SOH value, a relative SOH evaluation method is presented for easier practical implementation. And then, multiple control loops are designed for achieving the expected operational performance. MATLAB simulation and experimental results are presented to verify the proposed control method.

This paper concentrates on the problem of control of a hybrid energy storage system (HESS) for an improved and optimized operation of load-frequency control (LFC) applications. The HESS consists of a supercapacitor served as the main power source, and a fuel cell served as the auxiliary power source. Firstly, a Hammerstein-type neural network (HNN) is proposed to identify the HESS system, which formulates the Hammerstein model with a nonlinear static gain in cascade with a linear dynamic block. It provides the model information for the controller to achieve the adaptive performance. Secondly, a feedforward neural network based on back-propagation training algorithm is designed to formulate the PID-type neural network (PIDNN), which is used for the adaptive control of HESS system. Meanwhile, a dynamic anti-windup signal is designed to solve the operational constraint of the HESS system. Then, an appropriate power reference signal for HESS can be generated. Thirdly, the stability and the convergence of the whole system are proved based on the Lyapunov stability theory. Finally, simulation experiments are followed through on a four-area interconnected power system to demonstrate the effectiveness of the proposed control scheme.

In this paper, the computational problems associated with the optimization techniques used to evaluate the switching patterns for controlling variable-characteristics active power filters are presented and critically analyzed. Genetic algorithms (GAs) are introduced in this paper to generate a fast and accurate initial starting point in the highly nonlinear optimization space of mathematical optimization techniques. GAs tend to speed up the initialization process by a factor of 13. A combined GA/conventional technique is also proposed and implemented to reduce the associated computational burden associated with the control and, consequently, increasing the speed of response of this class of active filters. Comparisons of these techniques are discussed and presented in conjunction with simulation and practical results for the filter operation.

The purpose of this paper is to use bond graphs to retain system structures, linking dynamic models and the transfer functions of control systems, and develop a universal analysis method for eliminating the right-half-plane zeros (RHP-zeros) of systems. Although previous literature has investigated RHP-zero elimination, their findings were only applicable to specific systems. When such a system is modified, only a trial-and-error method can be applied to eliminate the RHP-zeros of systems. The main feature of the proposed method involves the analysis of the causal paths contained in bond graphs. Analysis results then serve as a guideline for RHP-zero elimination, which can involve processes including modification of model structures or changes to paths. This method improves the system to get a better performance, instead of using the trial-and-error methods. Finally, a boost converter with an RHP-zero is applied to various examples of RHP-zero elimination, verifying that the proposed methodology can be used to eliminate the RHP-zeros of systems without the need of a trial-and-error process.

This paper proposes a magnet-frozen-permea-bility finite-element method and an experimental approach for inductance analysis of a variable-flux permanent magnet machine. The machine studied uses Alnico magnets, whose nonlinear magnetic properties deteriorate the inductance calculation accuracy. Besides the machine core permeability is frozen, the magnet-frozen-permeability approach freezes nonlinear B–H curves and nonlinear permeabilities of the magnets in the finite-element analysis. Because the soft magnets have low coercive force, conventional symmetric inductance measurement currents may demagnetize them. This paper presents a zero-start dc-biased current trajectory tracking approach. This approach uses positive current, which avoids demagnetization during the inductance measurement. Meanwhile, based on flux linkage-current curves, influences of resistance can be eliminated. Cross-magnetization effects are evaluated in the two proposed methods. Inductances of these two methods are compared and show good agreements.

A single gimbal control moment gyro (SGCMG) has been designed and developed as a torque amplifier to generate 1.2-Nm–5-Hz gyroscopic torque for the angle deviation of 45°. Since the SGCMG is aimed to generate the torque accurately in the designated direction, the return of the gimbal from the disturbance should be guaranteed within a desired frequency. However, unexpected axial drift exists and leads to a null motion under the torque control scheme. Therefore, this paper identifies the cause of axial drift and proposes a new torque control technique with two phases of compensation. Compensator I is designed to eliminate the nonlinear axial drift modeled as a sigmoidal function through an empirical identification process. Compensator II reduces other uncertainties by integrating high-pass filtering, recursive least square, all pass filtering, and moving average filtering (MAF) process. Finally, the proposed control scheme has been verified through experimental studies.

With high production efficiency and robustness, automatic component pick-and-place technology is widely used in modern electronic industries. As one of the core components of this technology, the visual measurement system requires a suitable positioning and fault detection algorithm with high speed, accuracy, robustness, and generalization abilities, especially for positioning and inspecting ball grid array (BGA) components. This paper examines the online positioning and defect inspection problem of BGA components for component placement machines. Incorporating coarse and fine positioning, an accurate, efficient, and robust universal positioning algorithm is proposed. Two types of key points are introduced to characterize the alignment of solder balls in BGA components. A distance transform-based circle detection method is first applied, and then a distance-based edge filter and a circle fitting method are employed to obtain the coarse and fine locations of solder balls, respectively. The approximate location of the component is estimated using a geometrical method and the fine location is calculated by solving a least-squares problem. A pair of overlapping ratios is introduced to conduct fault detection and inspect the alignment accuracy. The effectiveness of the proposed method is verified by applying it to several real component positioning and defect inspection experiments.

Microinverters require high voltage gain capability for interfacing the low dc voltage output of photovoltaic (PV) module to single-phase ac grid. A two-stage nonisolated inverter is proposed in this paper, with a first boost stage and a second traditional pulse width modulated grid-tied inverter stage. The proposed boost stage consists of a coupled inductor added with a voltage multiplier to achieve the required high voltage gain at high efficiency and to operate over a wide input voltage range. Among the coupled inductor topologies, adding a clamp circuit is a common solution to limit the voltage spike caused by leakage inductance. In the proposed converter, the resonance between the coupled inductor and voltage multiplier is used to address the issue of voltage spike, thereby reducing both component count and device voltage stress. Detailed analysis and design procedure of the proposed converter is presented in this paper. Experimental results of a 250-W microinverter are presented to validate the proposed converter.

This paper extends the trans-Z-source concept to ac–ac power conversion and proposes a novel single-phase trans-Z-source ac–ac converter. The proposed converter retains the advantages of its existing Z-source/quasi-Z-source counterparts in which the output voltage can be boosted and in-phase with the input voltage or bucked/boosted and out-of-phase with the input voltage. Meanwhile, a coupled inductor is introduced into the proposed converter, and the turns ratio of the coupled inductor become another control variable beside the duty cycle to obtain extreme voltage gain. Importantly, the input voltage and output voltage share the same ground, and the input current could be continuous, which is a benefit for reducing input current harmonics. Most important of all, the safe-commutation strategy for the proposed converter is deep developed, and analytic expression between the switches state and loop circuit voltage/current condition is derived out. Hence, the current/voltage ripple can be avoided without a loss snubber circuit, which benefits a reduced cost and enhanced reliability. The performance analysis is discussed in consideration of parasitic resistance, and system parameter design is optimized based on theoretic calculation. A laboratory prototype is fabricated, and experiments are performed to verify the validation of the proposed converter.

The 12-pulse rectifier is often used to supply high-power industrial loads. Its ability to effectively and cheaply mitigate the harmonics on the ac side has ensured its dominance in the industry even as active front ends become cheaper and more reliable. Despite its many benefits, the 12-pulse rectifier is not able to reduce the ac-side harmonics to a level acceptable by the pertinent IEEE standards without additional filtering. In this paper, we outline a novel method to profile the rectifier output current to be triangular which results in low ac-side harmonics. The novelty in the proposed approach is that we exploit the dc-side filter design to minimize the volt-amperes (VA) rating of the current source used to profile the dc-side rectifier current. Additional benefits of the proposed method include lower VA rating of the dc filter, simple integration of dc energy storage, and effective ac harmonic control even when the initial rectifier current is discontinuous.

This paper presents a solution for the voltage balance problem of the series-connected devices that can be applied to multilevel converters in which the series-connected devices need to block twice their switched voltage. The solution is based on two ideas, the control of the switching commands to achieve proper switching losses balance and the use of additional circuitry to achieve proper voltage balance during their blocking state. The proposed strategy is experimentally validated into a 5-level multipoint clamped full-scale converter. However, it can be used in any other converter topology in which the devices need to block twice their switched voltage.

Flux-weakening control for induction motor (IM) in voltage extension region (outside the inscribed circle but in the hexagon) is meaningful to yield a further maximum torque. However, as the voltage-limit trajectory migrates out of the inscribed circle, torque ripple becomes more severe. Meanwhile, the insufficient voltage margin results in the degradation of current dynamic performance in transition period (from base speed region to flux-weakening region), especially in harsh conditions, e.g., a step speed command. To address the problems above, this paper gives a quantitative analysis of the torque ripple and an explicit discussion on the current dynamic performance. A novel “Voltage Reference Adjustable” flux-weakening controller with “Self-Locking Limit Block” (SLLB) is proposed. There are two advantages. The first is the capability to operate in any voltage extension regions, offering a tradeoff between obtaining the maximum torque and suppressing the torque ripple. The second is an optimized voltage distribution, achieving a better track characteristic of d - and q -axis currents with the help of triggered SLLB in transition period. Experimental results on a commercial IM control system verify the validity of the proposed scheme.

Commutation error degrades the operating performance of a high-speed permanent magnet brushless dc motor (BLDC) sensorless drive significantly. It is caused by different kinds of nonideal factors such as low-pass filters (LPFs), digital control delay, and other units in a control loop. This paper analyzes the commutation error caused by different kinds of nonideal factors and points out that the total commutation error is substantially equivalent to the error of an internal power factor (IPF) angle of the BLDC motor. The purpose of the commutation correction in this paper is to regulate the IPF angle to zero. A novel phase-lock loop (PLL)-based commutation correction strategy is proposed and designed in detail in this paper. The proposed PLL consists of a novel PM flux linkage based phase discriminator to detect the IPF angle, an LPF, and an autophase regulator (APR). The function of the proposed PLL is to lock the IPF angle to a reference value. Compared to the conventional scheme, the greatest advantage of the proposed scheme is that the proposed PLL is robust to any kind of phase delay caused by nonideal factors in the control loop, and it is quite important for a high-speed motor drive. Both simulation and experimental results verify the effectiveness and superiority of the proposed correction strategy.

In order to improve the performances of switched reluctance machines (SRMs), such as torque production and power density, combining segmented structure and hybrid-excitation is a proper and useful method. This paper develops a kind of segmented-stator hybrid-excitation SRMs (SS-HESRMs) assisted with permanent magnets (PMs) and investigates on them with different rotor pole numbers. To evaluate the effects of different rotor topologies, the static magnetic characteristics and dynamic performances of two SS-HESRMs with 12/10 and 12/8 poles are briefly presented. Moreover, both SS-HESRMs are compared with two segmented-stator SRMs (SS-SRMs) which have the same basic structure and stator/rotor pole combinations but without PMs. The results reveal that SS-HESRMs produce higher electromagnetic torque than SS-SRMs with the same stator/rotor pole configuration. The 12/10 SS-HESRM exhibits better characteristics, such as higher dynamic average torque, lower torque ripple, and higher power/torque density, than the 12/8 SS-HESRM at low-speed operation. While at high speed, the 12/8 SS-HESRM exhibits better characteristics than 12/10 SS-HESRM. The 12/10 SS-HESRM has stronger starting capability but lower steady-state speed under the same starting condition. Finally, a 12/10 SS-HESRM and a 12/8 SS-HESRM with the same structure and size are prototyped and tested to confirm the predictions.

In applications that demand single-input dual-output (SIDO) or dual-input single-output (DISO) dc–dc converters, employing two separate single-input single-output (SISO) converters is a solution. However, the number of components is doubled, resulting in high overall cost. In order to reduce costs, this paper proposes a novel topology synthesis methodology, with which a variety of SIDO and DISO dc–dc converters with reduced components can be derived. The principle of topology synthesis states that integrated SIDO and DISO dc–dc converters can be easily developed from conventional SISO converters by replacing a diode with a basic cell inclusive of additional input/output port. The principle is effective for many SISO dc–dc converters, and as an example, topology synthesis based on buck, boost, buck–boost, Cuk, sepic, and zeta SISO converters is performed in this paper. In order to achieve better understanding of the proposed converters, the integrated SIDO Cuk converter is specifically analyzed and experimentally verified. In comparison with the conventional scheme of two separate SISO Cuk converters, good cross regulation is retained while the number of diodes, inductors, and capacitors is reduced in the proposed SIDO Cuk converter. In addition, zero-voltage-switching operation of one switch is achieved, contributing to lower switching losses. Finally, a prototype circuit with 48-V input and 156 V/1 A, 24 V/4 A outputs is built to validate the theoretical analysis.

In this paper, a novel natural frame control is proposed for a single-phase cascaded H-bridge (CHB) multilevel converter. Natural frame control can acquire sinusoidal current waveform and achieve the balanced control of dc-link voltage without phase-locked loop or any coordinate transformation. Compared with conventional single-phase dq control, it only needs an imaginary voltage component without requiring an imaginary current component, which can eliminate additional current delay. Moreover, a new imaginary voltage construction method, referred to as fictive-phase construction (FPC), based on phase leading is presented. The delay time of FPC is only 1.67 ms theoretically under the condition of 50-Hz frequency, which is faster than the existing delay time of 5 or 3.33 ms. This effectively improves the real-time performance of the system when grid voltage fluctuates. Simulation and experimental results for a three-cell CHB converter validate the proposed control method.

A nonisolated single-stage electronic lighting system with a high power factor for driving power light-emitting diodes (LEDs) is proposed in this paper. The presented topology is based on the integration of a bridgeless boost rectifier with a nonresonant half-bridge converter. Accurate steady-state analyses of the nonresonant- and resonant-based circuits are reported, serving as the basis for designing the lighting systems. The LEDs current is adjusted by means of frequency modulation, being the converter switches driven by complementary symmetrical signals. A small-signal analysis is detailed for the proposed nonresonant scheme, providing fundamental information regarding its dynamic behavior. Also, a step-by-step design procedure based on the performed mathematical analysis is elaborated, allowing the adequate design of the proposed lighting system. In order to confirm the validity and the feasibility of the proposed converter, experimental results for a 42-W, 127- ${\rm{V}}_{{\rm{rms}}}$ , 50-kHz, 94.2% peak efficiency prototype are presented.

To improve light load efficiency, a three-phase photovoltaic (PV)-based microinverter may operate in single-phase, two-phase or three-phase mode depending on the available input power. Therefore, its dc-link capacitor may be subjected to large peak-to-peak voltage ripple when operating in phase skipping mode. This paper determines the minimum value of the dc-link capacitor by allowing the maximum acceptable voltage ripple on the dc link. This allows for the use of film capacitors instead of electrolytic capacitors in order to improve the microinverter reliability. Unfortunately, higher dc-link voltage ripple introduces harmonic distortion on the inverter output current waveform if it is not compensated for by the dc-link voltage controller. This paper proposes a simple synchronous control method to regulate the dc-link voltage with the presence of large voltage ripple. The dc-link voltage controller is synchronized with the phase-locked loop and samples the average value of dc-link voltage without introducing unwanted harmonics into the voltage sense path. Experimental results were obtained from a 300-W three-phase half-bridge microinverter prototype to verify the proposed dc-link voltage control performance. Inverter output current total harmonic distortion of 1.6% was achieved even though the dc-link peak-to-peak voltage ripple reached as high as 87 V with 219-V split dc-link voltage. Dynamic response is fast enough to easily track the most extreme ramp change in input PV power.

This paper deals with a control technique of a three-phase grid connected solar photovoltaic (SPV) system, which is based on the fast zero attracting normalized least mean fourth algorithm. This control algorithm achieves the objectives of mitigation of power quality issues such as harmonics reduction and power factor correction, together with extraction of peak power generated by the PV array. The system uses a PV array, a voltage-source converter (VSC), and linear and nonlinear loads. Here, VSC is connected to a PV array to transfer the active power to the three-phase load and the grid. The dependence on tuning of proportional-integral controller is reduced because of the feedforward term of the PV power. Due to this, the system dynamic response is improved, which makes the system quite robust. The system goals are to mitigate power quality problems and to provide current conditioning while operating in coherence with a weak distribution grid, which has poor quality of power in terms of voltage distortions with imbalances. MATLAB/Simulink is used to develop the model of the proposed system. The validation of proposed control is done at varying linear and nonlinear loads and under different environmental conditions on a prototype developed in the laboratory.

In this paper, a DC-link voltage protection (DCVP) control method is proposed to address the DC-link overvoltage issue due to power back-feeding in parallel Uninterruptible Power Supply (UPS) system. The proposed control method is able to protect the inverter against the excessive DC-link voltage, which increases the system reliability and robustness. Moreover, a current sharing control strategy is proposed by online regulating the virtual resistance of each UPS module. The proposed current sharing control strategy is able to address the circulating fundamental and harmonic current caused by the line impedance mismatching or power back-feeding issue in the UPS system. In addition, an improved consensus-based distributed controller is proposed to alleviate the overshoot issue during the transient process in voltage amplitude and frequency restoration. Finally, the feasibility of the proposed methods are verified by experimental results from the parallel UPS prototypes.

This study proposes a novel prosthetic hand that can artificially replace human sensation using haptic transplant technology. Conventional motorized prostheses are unable to precisely control the grasping force of the hand due to the lack of force sensation. In this paper, a haptic prosthetic hand is developed that allows for intuitive operation and precise force adjustment. These functions are realized by artificially transplanting the tactile sensation of a healthy part of the user's body to the amputated part of their body. The haptic transplant technology transmits the force sensation of the prosthesis to the master interface attached to the amputee's healthy part of body using bilateral control without a force sensor. Furthermore, variable compliance control is proposed for flexible adaptation to the shape of the object being grasped. The effectiveness of the proposed system was experimentally verified by comparing the controllability of the proposed system with that of a myoelectric prosthesis. In summary, an artificial replacement for human sensation was developed, and the intuitive operability and flexibility of the proposed system were confirmed.

The control loop stability in boost converters operating in continuous conduction mode has been restricted due to its nonminimum phase nature: the presence of a positive zero (right-half plane zero) in the control to output voltage transfer function. This paper proposes a method to mitigate the effect of the zero on the control loop by shifting the position of the zero to the left-half plane and hence leading to increased stability for the control loop of the boost converter. Superior performance of the proposed method has been clearly demonstrated using simulation and experimental results.

This paper proposes a practically oriented finite-time control design for nonlinear systems under a less ambitious but more practical semiglobal control objective. As one main contribution, the designed finite-time controller can be expressed as a very simple form while the control gain tuning mechanism follows a conventional pole placement manner, which enhances its facility in practical implementations. Moreover, by utilizing a modified nonrecursive homogeneous domination design without preverifying any nonlinearity growth constraints, the control scheme can be directly obtained by totally neglecting the recursive calculations of series virtual controllers. Rigourous semiglobal attractivity and local finite-time convergence analysis are presented to ensure the theoretical justification. A control application and experimental verification to a series elastic actuator demonstrates the control effectiveness and significant performance improvements compared with asymptotical state feedback controllers.

In the robust control of systems with dynamic uncertainty, there are mainly two methodologies: one based on the gain bound of uncertainty and the other based on the phase bound. The well-known small-gain approach belongs to the former and is able to conduct nonconservative robust performance design by using $\mu$ -synthesis. Meanwhile, the study on the latter case is still under way, and only a positive-real method was proposed by the authors recently to handle the robust performance synthesis. This paper aims at improving the positive-real method. The key idea is to model a passive uncertainty not only by its phase bound but also utilizing its largest gain. This is achieved by applying the notion of output strict passivity well known in nonlinear control. Furthermore, the negative-imaginary uncertainty can be treated in this framework more naturally. A case study on a vibration system validates the advantage of the present method.

Axial flux variable reluctance (AFVR) resolvers have substantial benefits that make them suitable for motion control drives. However, they suffer from insufficient accuracy, especially in high-accuracy applications. Hence, optimizing the AFVR resolver structure is necessary for improving its commercial usage. However, its accurate modelling needs three-dimensional (3-D) time stepping finite element analysis (TSFEA) that is computationally expensive and unsuitable for co-usage with optimization algorithms. The aim of this paper is to establish an accurate, yet computationally fast, model suitable for optimal design of AFVR resolvers. The working of the proposed model is based on magnetic equivalent circuit (MEC) and conformal mapping, which are in turn based on Schwarz–Christoffel mapping. The model uses conformal mapping to calculate reluctances that are used in MEC for calculating magnetic fluxes linkages, inductances, and induced voltages. Then, the induced voltages are used for calculating angular position. The results of the proposed model are compared with those of 3-D TSFEA. Finally, the experimental prototype is used to evaluate the developed analytical model.