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This paper deals with the control of a hybrid source combining a proton exchange membrane fuel cell and supercapacitors. To achieve this objective, an interconnection and damping assignment passivity-based control in a sampled-data context is implemented. This paper first details with this new controller and shows that it ensures the stabilization of the hybrid system at its desired equilibrium point under large range of sampling periods. These considerations are followed by a detailed discussion on experimental results achieved on a 1.2-kW test bench. [ABSTRACT FROM PUBLISHER]

This paper gives an overview of the topological variations of multi-winding induction machines (IMs) and drives. The study is restricted to IMs having two distributed windings on the stator and a brushless rotor. The mathematical modeling techniques and control algorithms available in the literature are highlighted. Being magnetless and brushless, a Dual Stator Winding IM is highly reliable, maintenance free, and economic. Thus, it possesses the necessary potential to become a part of ac and dc microgrids. Recent research trend shows growth in the application of such generators for off-grid and grid-connected systems. [ABSTRACT FROM PUBLISHER]

The acquisition of information on heat inflow is essential to the control of thermal displays and the rendering of thermal sensations. This paper addresses a method of estimating the amount of heat inflow without using a heat flow sensor and demonstrates sensorless heat inflow control using a Peltier device, which is often employed as a thermal device in thermal displays. Moreover, this paper introduces a method of identifying the thermal contact resistance of the device needed for the proposed observer. The observer estimates heat inflow by using information on electrical currents and temperatures. By using the observer instead of a heat flow sensor, which generally has a larger thermal capacity than a temperature sensor, an improvement in the response of a thermal device is expected. The applicability of the proposal is tested by experiments. [ABSTRACT FROM PUBLISHER]

A hybrid switched-capacitor/interleaved boost converter able to provide a high voltage gain and to cancel the input current ripple at a preselected duty cycle was recently presented in the literature. This paper extends that work by proposing an optimized switching strategy for operating conditions at other values of duty cycle. The switching strategy effect on the converter's voltage gain and input current ripple is quantified and compared against the performance under the conventional switching strategy. The approach is validated in the laboratory through hardware prototyping. [ABSTRACT FROM PUBLISHER]

This paper presents a topology for micropower piezoelectric wind energy harvesting useful for developing self-powered wireless sensor nodes. The features of the proposed topology, as compared with the existing piezoelectric/electromagnetic topologies, are as follows: 1) delivering power at high voltage levels, particularly at low-speed air flows; 2) starting operation at low cut-in speeds (about 1 m/s); and 3) robust structure for operating at high-speed wind flows practically tested up to 20 m/s. The proposed topology consists of a small fan with embedded permanent magnets (PMs) and a piezoelectric beam with a PM proof mass, which interacts with the PMs in the fan to harvest wind power. This paper also presents an analytical model and a design procedure to determine the number of PMs in the fan and their arrangements to maximize the captured power and minimize the cut-in speed. Using a prototype of the proposed topology, it is shown that the device starts capturing wind power at the wind speeds above 0.9 m/s. It is also shown that the suggested topology is at least 10% more efficient than the existing topologies in using piezoelectric materials and that its total volume power density is higher than those of the other topologies. [ABSTRACT FROM PUBLISHER]

In order to improve the availability of wind turbines and to avoid catastrophic consequences, the detection of faults in their earlier occurrence is fundamental. This paper proposes the development of a fault diagnosis scheme relying on identified fuzzy models. The fuzzy theory is exploited since it allows approximating uncertain models and managing noisy data. These fuzzy models, in the form of Takagi–Sugeno prototypes, represent the residual generators used for fault detection and isolation (FDI). A wind turbine benchmark is used to validate the achieved performances of the designed FDI scheme. Finally, extensive comparisons with different fault diagnosis methods highlight the features of the suggested solution. [ABSTRACT FROM PUBLISHER]

Motion control technologies are introduced in a huge number of products: electric vehicles, robots, mass storage areas, machine tools, etc. Many new products have developed based on previous studies on motion control. Recent achievements in motion control have indicated that innovation in this area is accelerating. For example, many companies have put robots with force sensing to practical use in the past few years. They have a wide variety of applications such as deburring, polishing, and assembling. Further development of haptics is strongly required for telesurgery, rehabilitation, and nursing care support. The development of high-accuracy positioning/tracking control has shortened the access time of mass storage areas. Sophisticated integration of actuators and sensors technologies has created many innovative techniques for new motion control systems. It is quite obvious that motion control is becoming more and more important as one of the key technologies in industrial electronics. Therefore, this "Special Section on New Emerging Technologies in Motion Control Systems - Part I" aims at presenting to the industrial electronics audiences the most advanced and relevant results in the field of motion control. The Guest Editors summarize the 14 articles from, various areas, that comprise the special section. [ABSTRACT FROM PUBLISHER]

In this paper, a photovoltaic (PV) microinverter capable of operating in both island mode and grid-connected mode by means of a reconfigurable control scheme is proposed. The main advantage of control reconfiguration is that in grid-connected mode, the microinverter works as a current source in phase with the grid voltage, injecting power to the grid. This is the operation mode of most commercial grid-connected PV microinverters. The idea is to provide those microinverters with the additional functionality of working in island mode without changing their control algorithms for grid-connected mode, which were developed and refined over time. It is proposed that in island mode, the microinverter control is reconfigured to work as a voltage source using droop schemes. These schemes consist in implementing P/Q strategies in the inverters, in order to properly share the power delivered to the loads. The aim of the paper is to show that the proposed control reconfiguration is possible without dangerous transients for the microinverter or the loads. Simulation and experimental results on an 180-W PV microinverter are provided to show the feasibility of the proposed control strategy. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to study the dynamics of a permanent magnet direct current (PMDC) brushed motor while two crucial space-domain effects, namely, slotting effect and commutation phenomenon are taken into account. Semi-analytical dynamic time-domain PMDC brushed motor model inclusive of these space-domain effects is used to analyze and investigate the dynamics. Pulse width modulation operated discontinuous current PMDC brushed motor drive with steady duty cycle is employed to acquire the bifurcation patterns. The chaotic nature due to slotting effect and commutation is identified from the bifurcation patterns and reported. It also has to be admired that such nonlinear dynamical behavior with the same set of parameters at similar operating condition has not been observed when a conventional PMDC brushed motor dynamic model is considered. These space-domain effects, namely, slotting effect and commutation also have a prominent impact to make some time-domain states of a PMDC brushed motor drive chaotic. The role of slotting effect and commutation phenomenon to analyze the chaos over time-domain state variables of the PMDC brushed motor drive is investigated and validated experimentally in this paper. [ABSTRACT FROM PUBLISHER]

The traditional evaluation method of vehicle noise can no longer meet the requirements of electric vehicle as the sound character of electric powertrain (E-PT) is totally different from that of internal combustion engine vehicles. This paper presents a complete investigation of the sound quality of an E-PT. An acoustic test is conducted to analyze the sound character of E-PT, based on which the acoustic origins of E-PT including electromagnetic noise, gear whine, and inverter switching noise are studied. After that the sound quality of E-PT is investigated by objective and subjective evaluations. Subsequently, a sound quality model of E-PT based on support vector machine is established. The relative error testifies the effectiveness of the prediction model. The influence of the main noise origins on the sound quality of E-PT is determined. Finally, the structure of gearbox housing is redesigned based on topology optimization to improve the sound quality. The main original contributions of this paper are not only the sound quality method developed for E-PT but also improvement feasibility of sound quality. [ABSTRACT FROM PUBLISHER]

SiC mosfet based converters are capable of high switching frequency operation. In this paper, the converter is operated with 50-kHz switching frequency for an active front-end rectifier application. Due to high switching frequency, the grid-side filter size is reduced, and the possibility of a high bandwidth current control loop is utilized in this paper. A current control loop with bandwidth of 5 kHz is designed using a proportional–integral controller in synchronously rotating dq-reference frame. In addition, the performance of the controller is tested under unbalanced input supply conditions. During this condition, new feed-forward signals, which are added to the controller output, are proposed. The gain of the feed-forward signal can be modified to achieve balanced sinusoidal grid currents, constant dc-link voltage, or a controlled negative-sequence input current, which are typical application-depending requirements. A closed-form formula to calculate the gain of the feed-forward signal to achieve the above-mentioned requirements is also proposed in this paper. To verify the proposed method, the simulation and experimental results are presented in this paper. [ABSTRACT FROM PUBLISHER]

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]

In this paper, the modular consequent-pole (MCP) rotor is adopted in the fractional-slot interior permanent magnet (IPM) machine to utilize the strong flux-focusing effect and reduce the leakage flux. Hence, the torque density and utilization ratio of permanent magnet (PM) material can be improved. However, the unacceptable unbalanced magnetic force (UMF) may arise due to asymmetric airgap flux density produced by consequent-pole topology. Thus, a pole-shaping method based on three-sectional arcs is proposed to suppress it. Due to the relatively complex rotor structure, the multiobjective optimization combined finite-element method with genetic algorithm is performed in this paper. Furthermore, the electromagnetic performance of the IPM machine with MCP rotor (namely IPM-MCP machine), including the open-circuit airgap flux density, phase back EMF, torque, PM utilization ratio, efficiency, flux-weakening capability and UMF, are compared with the conventional surface-mounted PM (SPM), IPM, and consequent-pole IPM (IPM-CP) machines. It is demonstrated that the IPM-MCP machine obtains the largest output torque in these machines. Meanwhile, the IPM-MCP and IPM-CP machines respectively have >30% and >20% higher PM utilization ratio than the conventional SPM and IPM machines while they obtain similar torque ripple and efficiency. Moreover, the IPM-MCP machine can obtain much lower UMF than the IPM-CP machine due to the effective suppression of asymmetric airgap flux density. Finally, a 12-slot/10-pole IPM-MCP machine is fabricated to verify the analyses. [ABSTRACT FROM AUTHOR]

The ability to monitor the quality of the metal forming process as well as the machine's condition is of significant importance in modern industrial processes. In the case where a physical device (i.e., sensor) cannot be deployed due to the characteristics of the system, models that rely on the estimation of both the applied force and the dynamic behavior of the machine (i.e., system) are adopted. The development of such models and the corresponding algorithms used to estimate the above-mentioned quantities has attracted the interest of the community. The main contribution of this paper is the estimation of a servo press force by employing a novel dual particle filter based algorithm, achieving a maximum relative error in the force estimation of 3.6%. Moreover, to address real-time performance requirements, this paper proposes a field programmable gate array based accelerator that improves the sampling rate by a factor of 200 compared to a processor-based solution, thus enabling the deployment of the system in many realistic scenarios. [ABSTRACT FROM AUTHOR]

Smart buildings form an integral part of the smart grid that lowers electricity cost. This objective can be achieved by using suitable enhanced algorithms and techniques. The motivation of this paper is the request for an economical decision-making system from a commercial company in Singapore. This paper presents an economical building management system (EBMS) concept inspired by the building management system and machine learning. EBMS improves the decision-making process through rule-based algorithm within the system. Machine learning algorithm is included as part of EBMS to enhance the computational calculation for the electricity distribution. It includes the function of self-making decision for purchasing electricity based on forecasting system for electricity price or real-time electricity price data when facility managers are not present. EBMS uses multiagent system to communicate, interact, and negotiate with multiple agents for energy supply and demand in the building. Simulation studies have shown the potential of EBMS concept to provide a cost reduction solution up to 61.42% savings for smart buildings. Better electricity purchasing contract option can be decided based on the forecasting system for building power consumption. [ABSTRACT FROM AUTHOR]

This paper aims to propose a new Vernier reluctance machine (VRM), which integrates the advantages of a robust rotor structure, good torque density, and flexible flux control ability. The key is to establish the excitation field with both stator slot permanent magnets (PMs) and zero-sequence current. Two excitation sources have different pole pair numbers but share a parallel magnetic circuit and contribute to superimposed torque in this machine. Meanwhile, a flexible flux control can be achieved by regulating zero-sequence current, and little demagnetization risk exists for slot PMs during flux control. In this paper, the machine configuration and operation principle are introduced, along with its integrated ac and dc drive method. Electromagnetic performance of this new machine is evaluated by finite-element analysis. Leading design parameters are determined and optimized considering optimal injection ratio of zero-sequence current. A prototype is fabricated, and relevant experiment results demonstrate the feasibility of the proposed solution. [ABSTRACT FROM AUTHOR]

In order to improve the performance of interior permanent magnet synchronous machine (IPMSM) based on space voltage vector modulation schemes, this paper presents a highly accurate online method to find the proper maximum-torque-per-ampere (MTPA) angles. This algorithm fully considers the nonlinear characteristics of the d-axis inductance, q-axis inductance, and permanent magnetic flux together. Additionally, the influences of temperature are taken into account. In this paper, the proposed method injects a small virtual angle signal into the current angle mathematically to track the stator current reference angle that is close to real MTPA points. Moreover, following a theoretical analysis method, the error of the virtual signal injection method is analyzed. Then, based on the results of error analysis, this paper proposes a compensation strategy that can significantly reduce the current angle error between the tracking point and real MTPA point. At last, various experiments on an IPMSM test bench verify the proposed control technique and overall performance. [ABSTRACT FROM AUTHOR]

In most multiobjective optimization problems of electrical machines, the weighted function method is used to convert them into single-objective optimization problems. This paper applies a kind of new multiobjective evolutionary algorithms (MOEAs), called adaptive multiobjective black hole (AMOBH) algorithms, to achieve effective multiobjective optimization of a tubular coreless linear permanent magnet synchronous motor (LPMSM). To reduce the computation cost of the MOEAs, a one-layer analytical model (AM) is presented for the tubular coreless LPMSM in this paper. The accuracy of the simplified one-layer AM is verified by comparisons with multilayer AM and finite element analysis (FEA) under different structure parameters. It is found that the simplified AM has good accuracy and can decrease the computation cost significantly. AMOBH algorithm is subsequently introduced. The optimal Pareto front with regard to thrust, copper loss, and permanent magnet volume are analyzed, and more diversified optimization results are provided. The final Pareto solution can be selected directly by practical physical values according to the application requirements. Finally, a prototype is fabricated for the selected design; its experimental results are provided and compared with those of the FEA results. [ABSTRACT FROM AUTHOR]

Soft robots have recently evoked extensive attention because of their abilities to work effectively in unstructured environments. As an actuation technology of soft robots, dielectric elastomers (DEs) exhibit many intriguing attributes such as large strain and high energy density. This paper presents a novel, DE-based, soft crawling robot inspired by inchworms. The kinematics of the soft crawling robot is explored, and a data-driven model is developed to facilitate the controller design. The overall controller incorporates a feedforward controller, a feedback controller, and a disturbance observer (DOB). The feedback controller and the DOB will compensate the disturbance and model uncertainties resulting from the obtained dynamic model and ensure robust performance of the robot under different conditions. The effectiveness of the proposed control scheme is verified using experiments on surfaces made of different materials and with inclined angles. [ABSTRACT FROM AUTHOR]

Printing of Hexadecanethiol (HDT) on thin gold substrates is the most common form of microcontact printing using self-assembled monolayers. The ability to visualize the HDT gold on a continuous moving Web, prior to subsequent steps, such as etching, is necessary to achieve any acceptable in-process quality control. In this paper, we present a real-time imaging technique for inspecting online print pattern in roll-to-roll process by condensation figures (CFs). The real-time desirable CFs are achieved through controlled consistent condensation of water vapor and a synchronous imaging process. The distribution of droplets of water acquired by fast-speed camera on an HDT-gold surface can be clustered and segmented for determining pre-etch pattern locations and geometries as well as print pattern evaluation. Our imaging system can achieve pattern resolution up to 0.7 μm, Web moving speed 3 in/s, given a low-cost camera with the frame rate up to 1500 fps. We demonstrate that the method can be promisingly used in combination with a pattern “truth table” for online quality monitoring and in-process control. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on current loop auto-tuning for self-commissioning of sensorless interior permanent magnet synchronous machine (IPMSM) drives. Well-tuned current controllers are essential for both high-performance operation and self-commissioning procedure. However, current controller design parameters, i.e., $L_{d}$ and $L_{q}$ , are not known at the beginning of the self-commissioning procedure where their estimation also has unique challenges. For example, an initial rotor position to determine the actual d- and q-axes is not known. Also, feedback controllers cannot be used in the estimation because they are not tuned yet. As a solution, this paper proposes a method to estimate the spatial inductance map by spatially scanning the motor via sinusoidal voltage injection in a controlled manner. Then it uses the estimated inductance values to tune the current controllers. The proposed method identifies $L_{d}$ and $L_{q}$ values using open-loop voltage injection without needing actual d- and q-axis positions. The whole procedure takes around a second. Practical considerations such as an automatic selection of the injection voltage, and digital control and dead-time effects are carefully addressed. The findings are experimentally verified on a 3-phase IPMSM drive. Furthermore, its applicability to different motor types is also demonstrated. [ABSTRACT FROM AUTHOR]

The rotor structure of synchronous reluctance machines (SynRel) is conventionally retained mechanically by iron ribs. In this paper, a novel structure for high-speed synchronous reluctance rotor is presented. The novelty of this paper is the proof of a concept of SynRel machine without iron ribs. Structurally, the rotor iron lamination segments are embedded in an adhesive resin material with high temperature resistance and mechanical strength. Three four-pole SynRel machines have been designed with the target of improving motor torque, and compared for different ribs configuration. It has been shown that the proposed motor performs enhanced torque, power factor, and efficiency with respect to conventional SynRel with iron ribs. An extensive sensitivity analysis of the ribless rotor geometry is carried out, followed by both mechanical analysis and experimental over speed test to guarantee its robustness above the operating speed range. The manufacturing procedure of this novel rotor is introduced. Finally, the experimental results on both SynRel prototypes are presented, showing the increase in torque, power factor, and efficiency of the proposed solution. This paper is a first step toward the definition of a viable and novel solution of SynRel machines with improved performance. [ABSTRACT FROM AUTHOR]

Nanorobotic manipulation technique has been regarded as one of the most dominating approaches to upgrade the functions of microscope benefits from its complex and precise operation system. At the current stage, although atomic force microscopy (AFM) is capable of mapping specimens on a two-dimensional/partial three-dimensional (3-D) plane, a full orientation of 360 $^{\circ }$ characterization still remains a challenge for AFM. Taking advantage of a nanorobotic manipulation system (NMS), 360 $^{\circ }$ mapping and 3-D reconstruction of topography and nanomechanical properties are presented in this paper. Compared with recent advances of AFM mapping techniques, our proposed method is able to realize effective, large area characterization and integral results can be directly perceived through 3-D reconstruction. In this paper, a six degrees-of-freedom NMS assembled inside AFM and task specification are first proposed. Second, home positioning method for effective specimen rotation scanning is introduced. Third, 3-D reconstruction methods for the topography and nanomechanical properties of the specimen are presented. After that, 360 $^{\circ }$ characterization of three different types of specimens, human hair (anisotropic biological material), trapezoidal cantilever, and conical micropipette (isotropic inorganic material) are adopted to demonstrate the feasibility and practicability of our proposed system. Finally, the 3-D reconstruction results of selected specimens are analyzed. This paper fills the blank of current AFM topography and nanomechanical characterization methodologies, which is expected to give a long-term impact in the fundamental nanomaterial research and practical micro/nano characterization. [ABSTRACT FROM AUTHOR]

This paper investigates a controllable fluke's regulation effect on the gliding motion of a self-propelled robotic dolphin in both theory and practice. In theory, based on a dynamic model, the gliding equilibria is first analyzed. Through deriving the explicit expressions of the pitch angle, gliding angle, and velocities, we explore how the deflection angle of the controllable fluke changes the gliding performance. Then, aided by these theoretical analyses, a pitch control strategy relying on the fluke is constructed. In simulations, the robotic dolphin is able to track a given pitch angle during gliding, directly through adopting this control strategy to regulate the fluke's deflection angle. Furthermore, extensive gliding experiments in different fluke's deflection angles are carried out. From the statistical data, we further explore the remarkable effects of the controllable fluke on the gliding performance in practice. Besides, the other pitch control experiment is also executed to validate the effectiveness of the proposed control approach. The results of this paper shed light on improving the gliding performance of the robotic dolphin in future mechanical design and gliding control. [ABSTRACT FROM AUTHOR]

The randomly switching communication topologies are of particular interest for researchers in the field of consensus control since the communication connection among multiple agents can randomly change with time and space. Following this pattern, this paper models the communication topology with the Markovian randomly switching graphs, since the Markovian chain process is usually used to model the network with Rayleigh fading channel. In this stochastic framework, this paper focuses on the consensus control and performance improvement problems of grouped agents with linear or linearized nominal dynamics. To solve this problem, a class of state-feedback controllers is proposed under the assumption that all the state measurements are available. These controllers are intrinsically distributed since they solely require the relative information between neighboring agents. Moreover, the notion of $\mathcal {H}_{\infty }$ ($\mathcal {H}_2$) stochastic consensus region integrated with transient performance is defined to measure the robustness of the proposed controllers with respect to the communication topologies. This paper theoretically shows that these controllers yield unbounded consensus region, which implies that they are well-designed. Furthermore, these controllers can improve the $\mathcal {H}_{\infty }$ , $\mathcal {H}_2$ consensus, and transient performances of agents subject to external and initial-state disturbances. At the end of this paper, numerical simulations and experiments are performed to verify the theoretical results. [ABSTRACT FROM AUTHOR]

This paper presents an improved equivalent input disturbance (EID) approach to deal with exogenous disturbances and system nonlinearities. The disturbances and nonlinearities are regarded as a lumped disturbance on the control input channel. The EID approach, which has a state observer and an EID estimator, is used to estimate the lumped disturbance. There is a constraint between the observer and the estimator on the design of the control system for the conventional EID approach. A stable zero was added to the estimator to remove the constraint and to improve the stability of the system in this paper. This ensures that the observer and the estimator can be designed independently. An analysis of the improved EID approach explains the mechanism of disturbance rejection. The simulation and experimental results of position control of a ball-and-beam system demonstrate the validity of the method. [ABSTRACT FROM AUTHOR]

This paper presents an integrated control strategy for a starter/generator (S/G) system based on five-phase dual-stator winding induction machine (FPDWIM). The FPDWIM has a cage-type rotor and two sets of stator windings. One is a five-phase control winding (CW), and the other is a five-phase power winding (PW). In the starting mode, the FPDWIM works as a motor. The CW provides both active power and reactive power to drive the engine. In the generating mode, the CW mainly handles reactive power while the PW outputs active power. To achieve the integration of the starting and generating controls, indirect CW-flux-oriented control (ICWFOC) to operate in both starting and generating modes is proposed in this paper. In starting mode, the CW current and flux are controlled to output a constant starting torque; while in the generating mode, both CW and PW dc bus voltages are regulated. In this way, the principles and structures of the control strategies in both modes are compatible, resulting in a simpler implementation and improved performance. With the proposed control strategy, the system can complete the starting–generating operation with a smoother transition process. Simulation and experimental results are compared to validate the proposed control strategy. [ABSTRACT FROM AUTHOR]

Series-connected-based offshore wind farms can eliminate bulky central offshore converters, transformers, and platforms. In a series-connected-based offshore wind farm, the dc voltage of the converters should be changed within a large range to control the dc-link voltage (grid side) and maximize wind power acquisition (generator side). In this paper, the full-bridge-based modular multilevel converter (FB-MMC) is proposed as grid- and generator-side converters. The dc voltage of the FB-MMC can vary in a large range because the full-bridge submodule (FBSM) is used. The control method of the FB-MMC in a series-connected-based offshore wind farm is different from those of traditional ones. The dc current control and capacitor voltage balance control are proposed in this paper, with which the FB-MMC can operate normally in the series-connected offshore wind farm. Moreover, the capacitor ripple voltage in the generator-side FB-MMC is studied. The result shows that the capacitor in the FBSM can be designed in rated power and frequency, and it will be feasible when the power and frequency decrease. Simulation and experiment results verify the feasibility of the proposed configuration and the corresponding control algorithm. [ABSTRACT FROM AUTHOR]

Due to different solar radiation, temperature, and other reasons of modules in the three-phase cascaded H-bridge (CHB) photovoltaic (PV) inverter, the output power among PV modules will be unequal and lead to unbalanced grid currents, which cannot meet the requirements of grid codes. On the other hand, the second-order voltage ripple is aroused in the dc-link capacitor since each phase-leg of the CHB inverter is made up of a single-phase inverter. Concerning these two issues, this paper proposes an optimized third harmonic injection method based on fundamental frequency zero sequence injection (FFZSI), which is a conventional method to handle the slight power imbalance problem. In this paper, the FFZSI is adopted to redistribute the power among three phases, and then the third harmonic is injected into the three-phase combined reference waveforms according to the two requirements: all modules are free from overmodulation and the dc-link voltage fluctuation is mostly reduced. Therefore, the proposed method can reduce the dc-link voltage fluctuation and extend the power balance range of FFZSI at the same time. The validity and effectiveness of the proposed method are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

A novel single-phase transformerless dual-mode interleaved multilevel inverter (DMIMI) is proposed in this paper, which can inject a highly sinusoidal ac current to the grid even with the input dc voltage less than the peak grid voltage. Furthermore, dead-beat controllers are developed to directly calculate the optimal duty cycles in a digital control platform. As compared to the traditional dual-mode multilevel approaches, the DMIMI offers high efficiency, less number of components conducting simultaneously in each operation mode, and the capability of reactive power exchange. This paper presents the theoretical analysis and the experimental results obtained from a 1-kW prototype. The experimental results reveal that the proposed DMIMI can achieve high conversion efficiency and low leakage current as well as high quality grid current. [ABSTRACT FROM AUTHOR]

Electro-hydrostatic actuator (EHA) is a highly integrated local hydraulic actuation system for more electric aircraft (MEA). However, the motor heating has always been the bottleneck in actual applications. In this paper, a novel energy-recovery EHA (ER-EHA) with specific hydraulic energy recovery unit is proposed to solve the problem. ER-EHA can reduce the heating of the motor, which is beneficial to improve the reliability and mean time before failure of the system. Besides, the power resistor is eliminated in the new system, so the volume of the system is reduced, and the power-to-weight ratio of the system is improved, which satisfies the needs of MEA. Simulations can prove the effect of energy recovery unit. To show the efficiency of our proposed structure, a specific test bench called redundant degree heterogeneous drives loads test bench is designed, and experiments are carried out in this paper. The results reflect its contribution to motor heating reduction. [ABSTRACT FROM AUTHOR]

This paper proposes a quadrature-shaped pickup coil, which can realize an angular-misalignment insensitive omnidirectional wireless charging system. Recently, the three-dimensional wireless charging has shown promising prospects for removing the performance deterioration caused by the positional misalignment, which can transfer power to arbitrary spatial objectives. In the conventional design, the strength and the direction of the induced magnetic field can be adjusted by controlling the excitation currents of transmitting coils. However, the existence of angular misalignment caused by the self-rotation of the pickup unit still can result in a sharp decrease of the transmitted power. Accordingly, this paper proposes and implements a novel pickup coil topology to compensate such huge fluctuations in power transfer, which aims to ensure an angular misalignment insensitive omnidirectional wireless charging. Simulated and experimental results are both given to verify the feasibility of the proposed quadrature-shaped topology. [ABSTRACT FROM AUTHOR]

Cascaded H-bridge converter (CHB) is a multilevel topology that is a well-suited solution for multiple applications such as flexible ac transmission systems or motor drives. This paper is focused on a CHB where the cells present an aging mismatch. This can be caused by the maintenance operation which forces the replacement of some damaged cells of the converter with new or repaired ones. In this paper, a new improved approach of the active thermal control (ATC) of the CHB using discontinuous pulsewidth modulation (PWM) (D-PWM) is presented. The D-PWM technique is used to reduce the power losses of one cell reducing its average temperature in order to increase its remaining lifetime. However, the combination of D-PWM with traditional phase-shifted PWM (PS-PWM) introduces high harmonic distortion in the output voltage of the CHB converter at twice the carrier frequency. A detailed harmonic distortion analysis of the CHB output voltage when the D-PWM based ATC is active is presented. From this analysis, a modification of the traditional PS-PWM is derived to eliminate the harmonic distortion at twice the carrier frequency. Experimental results show how the ATC using D-PWM is achieved whereas the harmonic distortion around twice the carrier frequency is eliminated. [ABSTRACT FROM AUTHOR]

This paper proposes a family of single-stage converters consisting of three different converters, each of which is able to produce a variety of waveforms through the waveform-subtraction technique. We brand this converter family as waveform-subtraction based single-stage converter (WSSC). By using only a single-stage converter, the proposed waveform generation technique is able to realize dc–dc–ac conversions and suppress input current ripple, meeting the needs of modernized power grid with renewable energy sources. At the same time, converters in this WSSC family are capable of generating a range of shapes, such as triangular, rectangular, and sawtooth waveforms, with simple structures, demonstrating its suitability of being applied in the electrochemical industry, e.g., in the electroplating process. Furthermore, the proposed family converters also realize substantially better input current ripple suppression compared to other conventional converters. In order to prove the validity and efficacy of the proposed WSSC and the theory underpinning it, in this paper, extensive simulations and analyses are conducted to verify the theoretical foundation of the proposed WSSC strategy, and the prototype of a converter from the proposed converter family is built and tested in our laboratory, which validates the functionality of the WSSC. [ABSTRACT FROM AUTHOR]

In order to suppress the torque ripple of an open-end winding permanent-magnet synchronous machine (OEW-PMSM), a q-axis current injection method is typically employed but the disturbances caused by the third flux linkage parameter mismatch can augment the torque ripple. To solve this problem, in this paper, first, a zero-sequence current (ZSC) and zero-sequence back-EMF observer (ZCBO) are proposed based on an adaptive sliding mode control, which is able to simultaneously estimate ZSC and zero-sequence back EMF under varying conditions. Based on this ZCBO, the estimated ZSC and zero-sequence back EMF could compensate for the one-step control delay and suppress the aforementioned disturbances. Second, although central hexagon modulation is employed in the predictive current control (PCC) scheme, zero-sequence voltage (ZSV) still exists in the zero-sequence path due to the dead time of the inverter, affecting the predictive accuracy of the ZCBO. To accurately establish the ZCBO, the ZSV caused by the dead time of the inverter is considered in the ZCBO. Finally, a comparative study of two types of methods is presented, and simulations established by MATLAB software and experimental confirmations are carried out to verify the effectiveness of the proposed PCC scheme in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes a sensorless vibration harmonic frequency estimation for a servo system driven by a permanent magnet (PM) synchronous machine. Traditional vibration harmonic estimation relies on the measurement using external sensors. An accelerometer is typically installed in the servo system to measure the vibration harmonic signal. Because the accelerometer must be attached on the visibly vibrational location inside the system, this vibration detection results in both issues about installation and reliability. To overcome this drawback, this paper proposes a disturbance observer to estimate the vibration harmonic by using current and position signal. A real-time signal process is developed to identify the vibration frequency from estimated harmonic. A servo system with a 400-W PM machine is built to verify the proposed vibration harmonic and frequency estimation. This paper includes the comparative evaluation between the accelerometer-based vibration harmonic measurement and the sensorless estimation. [ABSTRACT FROM AUTHOR]

With the proliferation of distributed generation in distribution networks, quickly and smoothly converting to a state of regional autonomy in the case of distribution network failure is one of the main challenges for the stable operation of a multimicrogrid (MMG). To address the aforementioned problem, this paper proposes coordinated control of the passive transition from grid-connected to islanded operation for a three/single-phase hybrid MMG. Under the premise of fully considering the constraints on the tie-line transfer power undertaken by the master power supply (MPS), the following two scenarios regarding safety and emergency are formulated: 1) when the output power of the MPS is in the safe range, the proposed strategy coordinates the energy storage (ES) in each submicrogrid (SMG) to achieve power balance; 2) when the output power is in the emergency range, this paper proposes a three-phase balance method based on a bubble sort to realize the combination optimization of the single-phase source-load-storage (SLS) and a fast power regulation method based on implicit enumeration for the SLS to reduce the tie-line transfer power, which could prevent failure of the mode transition from power overload. The test results verify the effectiveness and feasibility of the proposed coordination strategy. [ABSTRACT FROM AUTHOR]

Mass imbalance frequently exists in a rotating machine. It may induce unbalance force, causing undesirable vibrations and noise. Active magnetic bearing (AMB) has been found to be a good device to deal with such problem. This paper is concerned with the unbalance compensation for a three-pole AMB system. An adaptive compensation scheme is proposed based on the theory of immersion and invariance (I&I) control. It is to immerse a higher-order system into a lower-order target system. The lower-order target system in this paper is the three-pole AMB system with known mass imbalance and with a stabilizing integral sliding mode controller (ISMC). On the other hand, the higher-order system is the three-pole AMB system with both the ISMC levitation controller and the adaptive compensator. The adaptive compensator is designed to deal with the case that the mass imbalance may be unknown and may be changing during operation in practical applications. It estimates the information of mass imbalance online and is incorporated into the ISMC so that the unbalance force can be eliminated. Both numerical simulations and experimental results verify the effectiveness of the proposed adaptive compensator for mass imbalance. [ABSTRACT FROM AUTHOR]

Energy efficiency is a critical issue in the management of data centers, which form the backbone of cloud computing. Virtual resource management has a significant impact on improving the energy efficiency of data centers. Despite the progress in this area, virtual resource management has been considered mainly at two separate levels: application assignment and virtual machine placement. It has not been well-investigated in a unified framework for both levels, limiting further improvement in the energy efficiency of data centers. To address this issue, this paper proposes the virtual resource management problem for energy efficiency as a constrained optimization problem. Then, this paper simplifies the problem through profile-guided task classification and problem decomposition for complexity reduction and improved energy efficiency. After that, a three-phase framework and algorithms are presented for profiling and profile updating, task classification and application assignment, and successive virtual machine placement. Experimental studies show energy savings of 8–12% by the three-phase framework compared to the existing technique. [ABSTRACT FROM AUTHOR]

Disturbance observer (DOB) has been one of the most widely used robust control tools since it was proposed by Ohnishi in 1983. This paper introduces the origins of DOB and presents a survey of the major results on DOB-based robust control in the last 35 years. Furthermore, it explains DOB's analysis and synthesis techniques for linear and nonlinear systems by using a unified framework. In final section, this paper presents concluding remarks on DOB-based robust control and its engineering applications. [ABSTRACT FROM AUTHOR]

In this paper, the noncooperative optimal control problem is investigated for a class of discrete time-varying networked control systems subject to exogenous nonlinear disturbances. To relive the transmission burden in the sensor-to-controller channel, the Round-Robin protocol is adopted to schedule the sensor transmissions. On the other hand, the controller operates in an event-triggered manner so as to reduce the transmission frequency and thereby preserving the energy in the controller-to-actuator channel. In the presence of the underlying scheduling and triggering mechanism, it is literally impossible to acquire the accurate value of the individual cost function for each controller and, as an effective alternative, a certain upper bound is derived on the individual cost function. Then, in virtue of the completing-the-square technique and the Moore–Penrose pseudo inverse, such an upper bound is minimized at each time instant. Furthermore, a sufficient condition is established to guarantee the boundedness of the derived upper bound over the infinite horizon. Finally, a numerical example on the power grid is provided to verify the validity of the proposed methodology. [ABSTRACT FROM AUTHOR]

The increasing complexity of distributed real-time control systems in the vehicular area has led to the development of new protocols, such as controller area network with a flexible data rate (CAN-FD), that provides high-bandwidth communication with FD rate. Different topologies are used to interconnect electronic control units in safety-critical applications in the automotive area and the applied communication protocols, such as CAN-FD, must comply with reliability requirements. Moreover, the functional operations must be tested to their limits, since they require appropriate assessment techniques for different application scenarios. Recent research has highlighted that power switching systems cause transient faults that affect the communication network. In light of this concern, this paper explores the IEC/TS 62228:2007 and ISO 26262-3/4/9:2018 standards that can act as guidelines for the development of a test method and testing board for evaluating the impact of electrical fast transients on the performance of a distributed automotive control system. Metrics such as difference jitter, average jitter, and packet loss, are used to determine the fault impact on the control law of a critical vehicular control system. The experiments that were conducted show that during the four test scenarios in which the testing board was used, the average jitter increased from 10.41 to 29.05% in the worst case scenario. These results highlight the importance of carrying out consistent tests to prevent critical situations and that these data can be used in software requirements specification phases to improve reliability in vehicular control systems. [ABSTRACT FROM AUTHOR]

The development of wide band-gap semiconductor devices is rapidly promoting the development of power electronics technology, especially in high frequency (HF) power converter region. A category of HF power converter is switch-mode power amplifier (PA). This paper focuses on the implementation of a multiphase dc–dc PA with high bandwidth and high power rate. When naturally sampled phase-shifted carrier modulation is implemented in the practical digital control system to control this HF power converter, the pulsewidth error problem caused by limited domain frequency of control chip becomes much severer. As a result, dc voltage component of each phase becomes different under several conditions, leading to current imbalance among phase inductors. This paper analyzes this problem and proposes a sensorless control method to solve it, based on the injection of random sequence in reference wave. A four-phase prototype employing GaN devices is fabricated, switching at 1 MHz. Current imbalance and effectiveness of the proposed control method are verified by experimental results. The prototype is capable of uniformly amplifying sine signal within 200 kHz and a 350 kHz bandwidth random signal, with peak output power up to 810 W. [ABSTRACT FROM AUTHOR]

In this paper, quarter-turn planar transformer structure is proposed and implemented in an LLC resonant converter for server power supply applications. Main power losses of high-frequency resonant converters are secondary-side winding loss and transformer core loss. Conventional transformer winding structures limit the minimum number of turns on the primary and secondary sides, such that the core size and secondary-side conduction loss cannot be reduced by increasing the frequency. To achieve high efficiency and high power density, a fractional-turn transformer structure can reduce core volume and conduction loss in the windings. The optimized transformer design also enables the turn ratio of the fractional-turn to achieve normal coupling of primary and secondary sides without generating flux imbalance. The effects of different fractional-turn windings on efficiency are examined, and Maxwell simulation results are used to verify the structure and operation of the planar transformer. The printed circuit board layout is analyzed using Q3D Extractor to reduce the uneven current generated by parasitic components on the secondary-side windings. Wide-bandgap switches are utilized to implement a resonant converter with 1-MHz operating frequency, 380-V input voltage, 12-V output voltage, 1-kW output power, 37.6-W/cm3 power density, and 97% maximum efficiency. [ABSTRACT FROM AUTHOR]

This paper presents an optimization method for selective harmonic elimination in a cascaded multilevel inverter using teaching–learning-based optimization (TLBO). The main objective in selective harmonic elimination (SHE) strategy is to eliminate low-order harmonics by solving nonlinear equations and reaching optimal solution, while the fundamental component is satisfied. In this paper, in one side, the influence of optimal dc sources is investigated to reach the SHE goal, and in another side, comparing optimization methods is considered. In this paper, the TLBO as a recently emerged nature-inspired algorithm is presented to provide better results for the SHE in comparison with genetic algorithm, artificial bee colony, imperialistic competitive algorithm, harmony search, ant colony optimization, particle swarm optimization, and differential evolution. For better comparison of those methods and influence of optimal dc sources, 5-, 9-, and 15-level inverters are chosen and MATLAB software is used for optimization. Simulation results show the superiority of TLBO, higher precision and probability of convergence than other mentioned algorithms. Finally, to validate the influence of optimal dc sources and the accuracy of TLBO results, the experimental setup is conducted for a 5-level cascaded H-bridge inverter with optimal dc sources. [ABSTRACT FROM AUTHOR]

This paper describes the tuning process of the proportional-resonant controller, taking into account the significant computational delay from the digital control system. Different structures of the controller and related contradicting results are discussed. Particular attention is paid to the stability domain and its dependence on different parameters of the proportional-resonant controller. The main outcome of this paper consists in the tuning approach guidelines for selection of controller parameters in case of significant digital system delay. An optimal controller structure and start-up current optimization are proposed. All results are confirmed by simulation and experimental setup. [ABSTRACT FROM AUTHOR]

In this paper, the design methodology of switched-tank converter (STC) is presented. The power loss breakdown analysis is conducted to point out the directions and paths for components optimization. It is revealed that the switching device conduction loss, printed circuit board (PCB) loss, and inductor loss become significant when output power is >150 W. Power loss of four switches is calculated and compared for switching device selection. The resonant capacitor is carefully designed to meet both current stress and ripple requirements. On the other hand, optimal design of the resonant inductors and PCB layout are fully investigated. The core loss model is provided, and different core materials are compared to minimize the core loss. Besides, a fine-tuned inductor winding structure is designed to achieve the lowest winding loss. Furthermore, PCB layout is optimized to get short loop length for each operation state. In addition to the hardware level optimization, an improved control method is proposed, in which the conduction time of switching devices is tuned to mitigate the circulating power. To verify the optimization work, a prototype of STC is built and tested. The experimental results indicate that a state-of-the-art performance of 98.71% efficiency and a 1000 W/in3 high power density is achieved. [ABSTRACT FROM AUTHOR]

This paper presents a novel motion planning and tracking framework for automated vehicles based on artificial potential field (APF) elaborated resistance approach. Motion planning is one of the key parts of autonomous driving, which plans a sequence of movement states to help vehicles drive safely, comfortably, economically, human-like, etc. In this paper, the APF method is used to assign different potential functions to different obstacles and road boundaries; while the drivable area is meshed and assigned resistance values in each edge based on the potential functions. A local current comparison method is employed to find a collision-free path. As opposed to a path, the vehicle motion or trajectory should be planned spatiotemporally. Therefore, the entire planning process is divided into two spaces, namely the virtual and actual. In the virtual space, the vehicle trajectory is predicted and executed step by step over a short horizon with the current vehicle speed. Then, the predicted trajectory is evaluated to decide if the speed should be kept or changed. Finally, it will be sent to the actual space, where an experimentally validated Carsim model controlled by a model predictive controller is used to track the planned trajectory. Several case studies are presented to demonstrate the effectiveness of the proposed framework. [ABSTRACT FROM AUTHOR]

Active magnetic bearing is a core technology for high-speed rotational machines. Power electronics converter as the active magnetic bearing drive is the actuation unit and its topology highly impacts the performance of the bearing system. This paper introduces the progress of topology of active magnetic bearing drive. The initial topology of an H-bridge does not sufficiently utilize the power electronics devices. The topology with half-bridge and shared phase-leg has been proposed as the fundamental topology. In this paper, two approaches of novel magnetic bearing drive topology modification have been developed on the basis of the fundamental topology. In the first approach, central phase-leg for multiaxis magnetic bearing drive can be further shared and the power electronic devices can be globally optimized in the whole system. Further, a topology with current in the reverse direction can reduce the central phase-leg current rating and power losses. In the second approach, fault-tolerant magnetic bearing drive topology has been developed on the basis of the fundamental topology, too. It can ride-through the open-circuit fault of power electronics switch-in operation and keep levitation for the magnetic bearing. The series work of novel topologies can improve the performance of an active magnetic bearing system in application. [ABSTRACT FROM AUTHOR]

This paper presents the development of a Class-D full-bridge zero-voltage switching (ZVS) inverter, applicable to wireless power transfer (WPT) systems, operating at 13.56 MHz switching frequency with dynamic dead-time control (DDTC). Resonant-coupled WPT systems are being designed at ultrahigh switching frequencies to reduce the size of the wireless link and the passive components. Maintaining ZVS while controlling the output power delivered to a fixed or variable load is one of the major challenges of designing inverters at multi-MHz switching frequencies. DDTC is the approach deployed in this paper to sustain soft switching of a Class-D full-bridge inverter over the full range of output power while regulating the input dc bus voltage. Simulation results are presented to show that dynamically controlling the dead-time during input dc bus voltage variations reduces switch-node voltage overshoot, prevents large current spikes in the switching devices, and reduces associated high switching loss. Practical results obtained show that DDTC reduces switch-node voltage overshoot, increases the inverter efficiency, and reduces the steady-state temperature of the inverter during output power regulation. [ABSTRACT FROM AUTHOR]