• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-14
Mohammed Imthias; Krishna Raj R; Apurv Kumar Yadav; K. Gopakumar; Umanand Loganathan; Carlo Cecati

Multilevel dodecagonal voltage space vector generation scheme for variable speed drive applications with single DC link operation requires large value of capacitance for cascaded H-bridge (CHB) filters, when operated at lower speeds. In existing schemes, multilevel dodecagonal structure is obtained by cascading a flying capacitor inverter with a CHB. In this paper, a new scheme has been proposed to minimize the capacitance requirement for full speed operation by creating vector redundancies using modular and equal voltage CHBs. Also, an algorithm has been developed to optimize the selection of vector redundancies among the CHBs in order to minimize the voltage ripple of the floating capacitors. The proposed algorithm considers instantaneous capacitor voltages and phase currents for optimal selection of vector redundancies. A mathematical model for capacitor voltage deviation is presented and the effectiveness of proposed algorithm is verified in both simulation and experiment.

更新日期：2019-02-14
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-14

This paper presents the current control design procedure of a single-phase grid-tied 5-level Packed U-Cell inverter (PUC5) with LCL output filter. The PUC5 inverter is used as an interface of renewable energy sources like solar applications. The LCL filter is calculated according to the grid-tied operation and converter ratings. An optimal controller, based on linear quadratic regulator with integral action (LQRI), is designed to inject a sinusoidal current with low harmonic distortion at unity power factor. Required to that design, the PUC5 inverter is modelled in D-Q frame. The sensor-less voltage control is incorporated into the switching technique to balance the PUC5 capacitor voltage and generate 5-level waveform at the output. Experimental tests are performed on a laboratory benchmark to confirm the theoretical design. The results prove the efficiency and accuracy of the adopted control strategy in steady state and under transients of grid current, grid inductance, AC and DC voltage amplitudes.

更新日期：2019-02-14
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-13
Tianzhi Fang; Xianyun Zhang; Chun Huang; Wei He; Le Shen; Xinbo Ruan

Input-series-output-parallel (ISOP) inverter system is very suitable for high DC input voltage and large AC output current power conversion applications. If this topology is applied to the grid-connected occasion, a bulky-capacity grid-connected inverter can be built with multiple small-capacity standardized inverter modules, which could significantly improve the reliability of the system operation and facilitate system design. This paper investigates on ISOP LCL-type grid-connected inverter system, and it put forward an optimized way for the topology of combined LCL filters firstly. Then the inverter-side inductor current is carefully chosen as the controlled variable and thus a concise distributed control method is proposed to achieve multiple control objectives. On the basis of the presented distributed control, the redundant control technique is also provided to heighten the reliability of the grid-tied ISOP inverter indeed. Finally, a three-module prototype is built and the experimental results validate the effectiveness of the raised strategy.

更新日期：2019-02-14
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-13
Gab-Su Seo; Hanh-Phuc Le

This paper presents a new highly integrable hybrid step-down converter that merges switched-inductor (SI) and switched-capacitor (SC) 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.

更新日期：2019-02-14
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Stijn Kerst; Barys Shyrokau; Edward Holweg

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Kuo-Ching Tseng; I.-Chien Li; Chun-An Cheng

This paper proposes a novel isolated high step-down conversion circuit, called an integrated buck and modified push-pull (IBMPP) converter, which is able to lower the voltage level on the primary side of the ideal transformer, resulting in a lower turns-ratio and decreased leakage inductance. The IBMPP converter is able to prevent the duty cycle from operating in extremely low conditions. Furthermore, the proposed converter adopts active-clamp techniques to recycle leakage energy and to suppress voltage spikes, so that the conversion efficiency can be effectively improved. The advantages of the IBMPP converter are its simple topology, easy control mechanism (which requires only two signals with a 180-degree phase shift), high conversion ratio, low component counts for power switches, and less voltage stress on some of the switches on the high-voltage side. The operation principle, steady-state analysis, design considerations, and experimental results of the proposed IBMPP converter are presented in detail. The feasibility of the IBMPP is verified by hardware implementation. The full-load efficiency at 250W is 81.44%, and the input and output voltage are 380V and 5V, respectively.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Zhi Geng; Lihua Liu; Jutao Li; Fubo Liu; Qimao Zhang; Xiaojun Liu; Guangyou Fang

In complex terrain, Semi-airborne transient electromagnetic surveying can effectively solve the detailed exploration problems to replace ground manual operation. This method has the advantages of high efficiency, deep exploration depth and high signal-to-noise ratio. As the core component of the system, the constant-current transmission converter determines the primary field source of the surveying system. High-accurate and stable-output electromagnetic transmission technology is the key issues of the surveying equipment development. In this paper the converter circuit topology is designed in detail and a novel model reference adaptive Proportional-Integral (PI) control algorithm is put forward. The rising overshoot of current is eliminated and falling edge is linear. Finally, the 20kW high-power transmitting instrument has been completed and used for field experiments. A large number of experimental results show that the transmitting instrument can achieve high-power constant-current emission, stable output, and good dynamic performance. And the steady-state accuracy is better than the traditional transmitter. The converter successfully improved the semi-airborne transient electromagnetic system detection capability and achieved satisfactory results in field experiments.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Pok Wang Kwan; Xun Huang

Active flow control by means of plasma actuators has potential advantages over conventional strategies, e.g., mechanical or hydraulic components may be replaced by lightweight, compact, fast response plasma actuators. In this tutorial paper, several designs of dielectric barrier discharge (DBD) plasma actuators are presented for aerospace applications and the focus is on the associated feedback control implementation. The interdisciplinary nature of aerodynamic feedback control with plasma, however, makes direct experimental demonstration an outstanding challenge. Here we propose a realistic experimental control implementation afforded by commercial off-theshelf electric products and the major achievement is the detailed instruction (in both electricity and aerodynamics) and the successful demonstration of the closed-loop design in controlling the dominant modes from a cylinder flow set-up. The essence of our approach is to drive DBD plasma actuations by a downstream sensor and excite aerodynamic velocity perturbations, which are further amplified on the shear flow from the cylinder, leading to airflow structures such as vortex roll-up and randomization, which are measured by the downstream sensor to complete the whole loop. We benchmark our control approach by comparing to the predicted dominant frequencies of the controlled flow system, which can be achieved by Barkhausen stability criterion after establishing the corresponding transfer function of the whole flow control system. Overall, the current study shall assist a host of new applications in aerospace applications in the near future.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Jing Na; Yunpeng Li; Yingbo Huang; Guanbin Gao; Qiang Chen

Most of the existing control methods for servo systems driven by hydraulic actuators have been developed by using backstepping scheme and assuming that all system states (including internal hydraulic signals) are measurable. In this paper, we propose a new control design method for high-order servo systems with hydraulic actuator dynamics, where the backstepping scheme is avoided and only the system output (e.g., motion displacement) is required for the control implementation. For this purpose, the system model is first transformed into a canonical form, where the unknown dynamics in the system are lumped as one term. Then, we introduce a simple robust unknown dynamics estimator (UDE) that has only one tuning parameter but achieves exponential error convergence to accommodate the lumped uncertainties. Therefore, the function approximators (e.g., neural network and fuzzy systems) can be avoided, leading to reduced computational costs, simpler parameter tuning and improved convergence as compared to backstepping methods. Extensive simulations and experiments based on a realistic test-rig are conducted to show the efficacy of the proposed control.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Zaixing He; Zhiwei Jiang; Xinyue Zhao; Shuyou Zhang; Chenrui Wu

The 6D pose estimation of smooth metal parts is a common and important task in intelligent manufacturing. CAD-based monocular vision methods offer more advantages than other methods. However, they are subject to several drawbacks such as high complexity, low robustness, and unsatisfactory accuracy, which hinder their application in industry. In this paper, a new approach with corresponding practical algorithms is proposed to solve these problems. The proposed approach uses high-level geometric features, correlation of the straight contours, to represent the part. Moreover, it further exploits the matched special location points on the geometric features, which are the endpoints of the straight contours, to accurately estimate the 6D pose. Practical algorithms based on the modification of existing line feature descriptors are proposed to implement the approach. The experimental results revealed that the proposed approach and algorithms can achieve higher accuracy and robustness with fewer templates.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Feng Zhang; Yunxiang Xie; Yanshen Hu; Gang Chen; Xuemei Wang

For photovoltaic applications, the flyback micro-inverter with pseudo-dc-link is popular as a simple topology but brings large transformer turns ratio and thus large leakage inductance, which would deteriorate the converter efficiency. To solve this issue, based on the non-isolated pseudo-dc-link structure, this paper proposed a hybrid boost-flyback/flyback (BF/F) mirco-inverter. This new topology is operated at BF mode for the most segment of a half grid cycle and F mode for the rest. During the BF mode, high voltage gain with low voltage stress is easily available in minimized transformer turns ratio. Besides, the leakage energy is recycled and the turn-off voltage spike of main switch is clamped, as a result of a passive snubber inherently contained in this mode. Given that the BF mode is lack of step-down function, the F mode is developed to regulate the output voltage even for values lower than the input voltage. The operation and characteristic of the hybrid BF/F mirco-inverter in boundary conduction mode (BCM) are analyzed in detail, and the mathematical expression of reference current is derived theoretically to guarantee high power quality. Finally, a 240W prototype was implemented to validate the theoretical analysis and the benefits of the proposed topology.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Yunjia Li; Yuzhu Wang; Qi Cao; Jianan Cao; Dayong Qiao

A self-powered vibration sensor based on electromagnetic induction is presented in this work. The vibration sensor is implemented with stacked flexible coils and polymeric springs. The stacked flexible coil enables large output signal, while long and flexible springs enable high sensitivity and wide linear range of the sensor. At resonance, the sensor has a sensitivity of 1.83 V/g and a maximum resolution of 0.002g. In the high frequency range where the sensor output is frequency-independent (100 Hz-3000 Hz), the sensor has a sensitivity of 66.5 mV/g, a maximum resolution of 0.05g, and a measurement range up to 8.5g.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Xin Tong; Yan Su; Zhaofeng Li; Chaowei Si; Guowei Han; Jin Ning; Fuhua Yang

In this paper, we propose a novel method for pedestrian dead reckoning (PDR) using MEMS MARG (magnetic, angular rate, and gravity) sensors, which includes a double-step unscented Kalman filter (DUKF) and Hidden Markov Model (HMM) based zero-velocity-update (ZVU) algorithm. The DUKF divides the measurement-updates of gravity vector and magnetic field vector into two steps in order to avoid the unwanted correction for Euler angle error. The HMM-based ZVU algorithm is developed to recognize the ZVU efficiently. Thus, the proposed PDR method can reduce the position drift caused by heading error and fault zero velocity measurement. Experimental results demonstrate that the proposed method achieves better yaw estimate as well as zero velocity measurement and obtains more accurate dead-reckoning position than other methods in literature.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Jun Yik Lau; Wenyu Liang; Kok Kiong Tan

This paper presents a robust neural network with extended state observer control methodology for a piezoelectric actuator-based surgical device. This control methodology is proposed for tracking of desired motion trajectories in the presence of unknown or uncertain system parameters, nonlinearities including friction, hysteresis, and disturbances in the motion system. In particular, the radial basis function neural network, which serves as a function approximator, aims to create a model for an unknown function to find a relationship between input and output data. An extended state observer is utilised to assist in cancelling disturbances and uncertainties of the system dynamically. The stability of the control approach is analysed. The convergence of position and velocity tracking errors is proven theoretically. Experiments are conducted to demonstrate the performance with improved accuracy can be attained by the proposed control scheme. With the motion tracking capability, the control methodology helps the novel surgical device to achieve higher success rate in operation, which is also suitable for similar piezoelectric ultrasonic actuator applications.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date :
Pankaj Saha; Satadru Dey; Munmun Khanra

Supercapacitors are receiving significant interest in Wireless Sensor Network (WSN) applications due to their high power density and longer life-span. In such applications, consideration of leakage effect is crucial for online control and management of supercapacitors. Motivated by this fact, we propose an online scheme to estimate supercapacitor SOC, taking leakage effect into account. First, we propose a completely observable supercapacitor Equivalent Circuit Model (ECM) that captures the leakage effect. Then, we design an Unscented Kalman Filter (UKF) based SOC estimator on the proposed ECM. To illustrate the proposed scheme, we consider a commercially available 5 F supercapacitor (Maxwell BCAP0005) and conduct experimental studies to identify the ECM parameters. We also perform simulation and experimental studies to test the effectiveness of the proposed estimation scheme. Finally, we evaluate the robustness of the proposed scheme under parametric and measurement uncertainties.

更新日期：2019-02-11
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-07
Paolo Sassi; Paolo Tripicchio; Carlo Alberto Avizzano

This work introduces an intelligent system able to perform quality control assessment in an industrial production line. Deep learning techniques have been employed and proved successful in a real application for the inspection of welding defects on an assembly line of fuel injectors. Starting from state-of-the-art deep architectures and using the transfer learning technique, it has been possible to train a network with about 7 millions parameters using a reduced number of injectors images, obtaining an accuracy of 97,22%. The system has also been configured in order to exploit new data, collected during operation, to extend the existing dataset and to improve further its performance. The developed system showed that deep neural networks can successfully perform quality inspection tasks which are usually demanded to humans.

更新日期：2019-02-08
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-07
Sohrab Mirsaeidi; Xinzhou Dong

Failure of commutation process is a serious malfunction in line-commutated High Voltage Direct Current (HVDC) converters which mainly occurs due to inverter AC faults and may lead to outage of the HVDC system. In this paper, an improved strategy is developed that functions based on the SIEMENS HVDC control system under normal conditions and switches to a designed Commutation Failure Inhibition Module (CFIM) during an inverter AC fault. From the response speed point of view, since the designed CFIM does not require any PI controller, the inverter control system has a quick performance in prevention of the commutation failure. This is achieved by direct measurement of the overlap area using the waveforms of the valves anodecathode and commuting voltages. In addition, from the accuracy aspect, the proposed method has a superior performance in comparison with the existing strategies. It is because of the fact that by direct measurement of the overlap area, variations of both direct current and the commutation inductance are considered, and hence, the unnecessary increase of the inverter reactive power consumption during the fault and the repetitive commutation failures are prevented. The practical performance and feasibility of the proposed strategy is validated through laboratory testing, using the real-time Opal-RT hardware prototyping platform. The experimental results demonstrate that the proposed strategy can effectively inhibit the commutation failure or repetitive commutation failures under different fault types by considering the lowest possible reactive power consumption.

更新日期：2019-02-08
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01

This paper presents an analytical method for the design and power optimization of vacuum-packaged piezoelectric energy harvesters. It is shown that the maximum power point of a vacuum-packaged energy harvester is different from the conventional one which occurs when the electrical damping ratio equals to its mechanical counterpart. Also, it is shown that the captured power by a vacuum-packaged energy harvester is highly sensitive to the vibration frequency due to very low-mechanical damping ratio, e.g., up to 50% power drops corresponding to 2% deviations in the frequency. The analysis and design are performed in the context of an ac-line magnetic field energy harvester in which the line frequency is also fixed and this energy harvester is useful for developing the self-powered wireless monitoring devices. Furthermore, the vacuum-packaged devices are inherently robust against dust storm and icing phenomenon, which occur for overhead power lines. The proposed analytical method is established based on simplified assumptions and then an accurate method is developed for the analysis of vacuum-packaged devices. Obtained theoretical results are verified in the laboratory through a prototype of the vacuum-packaged piezoelectric device, which captures up to 90 $\mu$ W from a 10-A line current.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01
Xiaoyan Li; Xiangyang Xing; Chenghui Zhang; Alian Chen; Changwei Qin; Guangxian Zhang

The improved LCL filter is used in transformerless three-level photovoltaic inverter system for leakage current suppression. However, the common-mode (CM) resonance circulating current (CMRCC) is generated, which causes inverter-side current oscillation, leakage current increment, and system instability. To overcome these issues, an improved CM circulating current model with detailed analyses of CMRCC is proposed in this paper. Based on above theories, the CMRCC is influenced by filter parameters, zero-sequence duty ratio, and number of switching transitions. To suppress CMRCC, a hybrid control strategy composed of proportional integral (PI) and feedforward control is presented. It is realized by real-time adjusting zero-sequence duty ratio in space vector modulation technique. Compared with the conventional damping resistor techniques, the CMRCC and leakage current are effectively suppressed with the proposed method. Thus, the performance of inverter-side currents and leakage current suppression is greatly improved. Besides, the capacitor-voltage-feedforward control is adopted to eliminate resonance peak in the differential-mode circuit. Simulation and experimental results are given to demonstrate the effectiveness of theoretical analyses and the proposed method.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01
Osama M. Hebala; Ahmed A. Aboushady; Khaled H. Ahmed; Ibrahim Abdelsalam

This paper presents a comprehensive and generalized analysis of the bidirectional dual active bridge (DAB) dc–dc converter using triple phase shift (TPS) control to enable closed-loop power regulation while minimizing current stress. The key new achievements are a generic analysis in terms of possible conversion ratios/converter voltage gains (i.e., Buck/Boost/Unity), per unit based equations regardless of DAB ratings, and a new simple closed-loop controller implementable in real time to meet desired power transfer regulation at minimum current stress. Per unit based analytical expressions are derived for converter ac rms current as well as power transferred. An offline particle swarm optimization (PSO) method is used to obtain an extensive set of TPS ratios for minimizing the rms current in the entire bidirectional power range of –1 to 1 per unit. The extensive set of results achieved from PSO presents a generic data pool, which is carefully analyzed to derive simple useful relations. Such relations enable a generic closed-loop controller design that can be implemented in real time avoiding the extensive computational capacity that iterative optimization techniques require. A detailed Simulink DAB switching model is used to validate the precision of the proposed closed-loop controller under various operating conditions. An experimental prototype also substantiates the results achieved.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15
Jun Zeng; Qiaoqiao Wang; Junfeng Liu; Jianlong Chen; Haoyong Chen

In view of Internet of Energy, advanced operational optimization in microgrid energy management system (MEMS) is expected to be scalable to accommodate various participants, support plug-and-play, and optimize energy utilization. Based on potential game, this paper presents a fully distributed operational optimization for MEMS with high penetration of renewable energy and demand response. After analyzing the microgrid and potential game, the establishment and proof of an exact potential game model is presented in detail. Then the best-strategy-response iterative algorithm is proposed to find the game Nash equilibrium in a distributed way. Finally, the proposed approach is simulated in an islanded microgrid to verify its efficiency and feasibility. The significances of this paper are as follows. First, the scheme and algorithm are fully distributed. All heterogeneous individuals are treated as independent decision-making entities without a central coordinator/processor. Second, the optimization process is open and dynamic. The convergence is achieved with no limits to type or number of players, even if the process of execution is corrupted with delay or losses in communication information. Third, the consistency between individual rationality and overall importance is guaranteed, and individual best-strategy-response behaviors necessarily improve overall optimality.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01
Shreelakshmi M P; Moumita Das; Vivek Agarwal

A novel bidirectional dc–dc converter having high voltage gain capability with high efficiency is proposed in this paper for interfacing storage in a range of applications. The proposed converter steps up (boost) the voltage in one direction while stepping it down (buck) in the other direction of operation. An attractive feature of the proposed converter is the symmetry of its operating modes. It also has inherent soft-switching capability during turn on of the switches, enabling high switching frequency operation. This, coupled with the fact that the proposed converter uses only one coupled inductor for both boost and buck modes, leads to a compact system. A clamped capacitor network is used to recover the leakage energy. Circuit description, design, and loss calculations for both buck and boost modes are explained. The bidirectional converter is designed for a voltage gain of 10 and (1/10) in the boost and buck modes, respectively. A 500 W laboratory prototype of the proposed converter has been developed and tested under rated conditions. Even for a large voltage gain of 10, a peak efficiency in excess of 94% is achieved, which is not possible with conventional converters. All the results of this work are included.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15
Hanzhen Xiao; C. L. Philip Chen

In this paper, an incremental centralized formation system is developed for controlling the multirobot formation with joining robots, and a nonlinear model predictive control (NMPC) method is implemented as the controller. The incremental updating method is used to update the system's state in real time, when there is a new robot joining during the formation process. Then, an NMPC approach is developed to reformulate the formation system into a convex nonlinear minimization problem, which can be further transformed into a quadratic programming (QP) with constraints. Then, a general projection neural network (GPNN) is implemented for solving this QP problem online to get the optimal inputs. In the end, two examples of incremental multirobot formation are demonstrated to verify the effectiveness of this method.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01
Qing Guo; Qiang Wang; Xiaochai Li

The disturbances suppression is one common control problem in electrohydraulic systems (EHSs) since both unknown external load and hydraulic parametric uncertainty often obviously degrade the tracking performance and bias the load pressure of EHS. In this paper, a finite-time convergent controller (FTCC) is tried to use in EHS to address this problem. Different from the asymptotic convergent controller, this FTCC not only improve the dynamic and steady tracking performance of the velocity servo system but also guarantee the system state error convergent to zero in a finite time. According to the finite-time stable principle, the FTCC is derived by backstepping and fractional-type Lyapunov techniques. The effectiveness of the proposed controller is verified by comparative simulation and experimental results with the other traditional and advanced controllers.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09
Zhe Li; Ling Zheng; Wenyun Gao; Zhenfei Zhan

This paper presents a control methodology for solving the vibration issues emerged in in-wheel motor electric vehicles (IWM-EVs). Unlike existing techniques and methods, the proposed investigation focuses on the electromechanical coupling effects between the subsystems in IWM-EV, which were considered as another negative effects bought by power integration. To this aim, an integrated model which describes the dynamic coupling process between electromagnetic excitation in motor and transient dynamics in vehicle is established and developed. The characteristics of the electromechanically motivated harassment are discussed and its coupling mechanism is analyzed. The key factors are extracted and adopted as the feedback signals in the design of control methods. The effectiveness verification is conducted within numerous practical scenario of vehicle dynamics. Theoretical analysis and simulation results reveal that the proposed approaches can prevent further enlargement of air-gap deformation and unbalanced electromagnetic excitation by cutting off the electromagnetic force outputting periodically, which are benefitted to attenuate the negative issues arisen by electromechanical coupling in IWM-EV. In addition, a more balanced outcome in vehicle dynamics is achieved by the independent-phase chopping method with a less side effect on output torque and speed tracking ability.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-09-03
Andres San-Millan; Sumeet S. Aphale; Vicente Feliu

Parameter uncertainty is a key challenge in the real-time control of nanopositioners employed in scanning probe microscopy. Changes in the sample to be scanned introduces changes in system resonances, requiring instantaneous online tuning of controller parameters to ensure stable, optimal scanning performance. This paper presents a method based on the frequency-domain algebraic derivative approach for the accurate online identification of the nanopositioner's parameters. The parameter estimates are produced within a fraction of one period of the resonant mode frequency, allowing almost instantaneous tuning of controller parameters. Experimental results show that the proposed method can be utilized to automatically tune an integral resonant control scheme that combines both damping and tracking actions, and consequently deliver positioning performance far superior to that achieved solely due to the scheme's inherent robustness properties. It is further shown that the achieved performance compares favorably with an optimally designed control scheme of the same type.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15
Weiwei Shang; Bingyuan Zhang; Bin Zhang; Fei Zhang; Shuang Cong

Cable-driven parallel robots (CDPRs) have low moving inertia and provide high-speed motion over a large workspace. The main challenges of CDPRs stem from the fact that cables should be in tension during motion control. Cable tension is closely related to the synchronization motion relation between cables which is often omitted in the existing controllers for CDPRs. To solve it, this paper proposes two synchronization controllers in the cable space to realize the synchronization motion between cables, and finally increase the tracking accuracy of the moving platform. The two synchronization controllers are proven to guarantee asymptotic convergence to zero of both tracking error and synchronization error. The trajectory tracking experiments are implemented on a self-built three-DOF CDPR, and the experiments are compared with the traditional augmented proportional-derivative controllers neglecting synchronization. The experimental results indicate that the tracking error and the synchronization error of the moving platform decrease greatly by using the synchronization controllers.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-24
Hongseok Cheon; Byung Kook Kim

In this paper, we propose a computationally efficient online local motion planning algorithm for mobile robots in unknown cluttered dynamic environments. The algorithm plans a trajectory incrementally up to the finite horizon in state-time space. Incremental planning method is capable of fast computation but has poor obstacle avoidance performance. To compensate for the drawbacks of incremental planning, a partial trajectory modification scheme is used that sets an interim goal and then plans a trajectory to pass through the interim goal. The interim goal is a temporary desired goal to prevent the robot from falling into the inevitable collision state. By using incremental planning and partial trajectory modification, it is possible to plan collision-free trajectory with small computation even in cluttered dynamic environment. To generate smooth trajectories around given waypoints and goal, we systematize bidirectional trajectory planning with three kinds of trajectories: 1) a forward trajectory from the current robot state; 2) a backward trajectory from the state of current target waypoint; 3) and a connecting trajectory between the forward and backward trajectories. A smooth trajectory is generated around the way point and goal by setting the state of the current target waypoint (or goal), while taking into account the positional relationship among the planned forward trajectory, the target waypoint and the next waypoint. Performances of the proposed algorithm are validated through extensive simulations and experiment with two types of mobile robots: 1) a holonomic mobile robot and 2) a differential drive mobile robot.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Mohamed Hassan Ahmed; Chao Fei; Fred Lee; Qiang Li

A high-efficiency, high-power-density Sigma converter for a 48V rack architecture in data centers is proposed in this paper. The Sigma converter is a quasi-parallel converter that uses a high-efficiency unregulated converter to deliver the bulk power to the load. A small buck converter is responsible for regulating the output voltage with prescribed dynamic responses. A design guideline for Sigma converter is provided in this paper. The unregulated converter is an LLC converter designed with a printed circuit board (PCB) winding matrix transformer, structure which integrates four elemental transformers into one core. The buck converter is designed with discrete gallium nitride (GaN) devices and a PCB winding inductor. The proposed Sigma converter operates at 48V input and 1V-80A output and can achieve a power density of 420 $W/in^3$ as well as a peak efficiency of 94 percent.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Lei Gan; Yulong Pei; Feng Chai

This paper proposes a novel tiered type permanent magnet spherical motor (T-PMSPM) of which the output torque is relatively higher than that of the most existing spherical motors. The proposed T-PMSPM has three stators along axial direction, each of the stator is consisted of an iron core and a three-phase winding. An analytical method is developed in order to calculate the tilting torque based on the air-gap magnetic field distribution generated with the specific pole-slot combinations. For performance verification and accurate calculation, three-dimensional finite-element analysis (FEA) is adopted. Two typical rotor configurations are compared and analyzed, focusing on the ability of large torque production, especially for the tilting torque. Finally, a prototype motor as well as the auxiliary apparatus used for experimental measurements has been manufactured. Considering that the friction torque is non-negligible, a test procedure of torque measurement and separation is designed and performed. The tilting torque obtained from the experiments is compared with the FEA results after friction compensation.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Minfan Fu; Chao Fei; Yuchen Yang; Qiang Li; Fred Lee

This paper develops a 200W two-stage rail grade dc/dc module based on gallium-nitride devices. It converts a wide input voltage (64V-160V) to a constant output voltage (24 V). Different devices and topologies are evaluated for the target application, based on which a two-stage configuration is proposed. The first stage is a two-phase regulated buck converter working under critical mode (>400 kHz), which is followed by an unregulated 48V/24V LLC converter (2 MHz) for 3000-V dc isolation. The voltage regulation is discussed for the buck converter when the inductors are negatively coupled, and then the ZVS extension is explored. However, due to the limitation of the digital controller, a trade-off is made between the dynamic response and the footprint. The compromise solution is to use a small and slow micro controller for high frequency control (including voltage regulation, critical mode operation, phase interleaving) and various demands (including soft start-up, external communication, and various protections). Finally, all the required functions are verified in a standalone quarter-brick prototype module. It can achieve 95.1% peak efficiency and $130W/in^3$ power density.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Hacy Bodur; Erdem Akboy; Huseyin Yesilyurt

In this paper, a new modular and active snubber cell, easily applicable and attractive for converters especially have many switches, is proposed. This snubber cell is implemented to single phase of grid connected three phase T-type three level inverter (T-3LI). At this new converter, the main switches turn on under Zero Voltage Transition (ZVT) and turn off under Zero Voltage Switching (ZVS). Also, auxiliary switches turn on under Zero Current Switching (ZCS) and turn off under ZVS. All snubber diodes operate under Soft Switching (SS). There are no additional current and voltage stresses on the main switches. During SS operation, the switching energies are transferred to a DC voltage source. Then, these energies are processed to input with independent DC-DC converter. Thus, all switching energies are recycled. In this study, principle operation and steady state analysis of modular and active snubber cell for single phase T-3LI are presented and experimental results, rated 1 kW and 100 kHz, are provided to verify theoretical analysis.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Yong Li; Jiefeng Hu; Xiaofei Li; Feibin Chen; Qiaodi Xu; Ruikun Mai; Zhengyou He

Current imbalance in multistring LEDs is a critical issue. It may cause overcurrent in one or more LED strings, leading to rapid degradation. In this paper, a mixed high order compensation networks based wireless power transfer (WPT) system is proposed to generate multiple constant current outputs. It is composed of an LCC resonant network in the transmitting side, a series resonant network and multiple CLC resonant rectifiers in the receiving side. The CLC resonant rectifiers are connected in parallel to form multiple independent output channels, and each channel is then connected to a LED string. Based on the analysis of the T resonant circuit and the modeling of coupling coils, multiple constant output currents can be derived. As a result, current balance can be achieved, which is very suitable for driving multistring LEDs. The proposed system also offers a modular, scalable and maintenance-free design, which can significantly reduce the construction cost and the control complexity. In addition, the inverter in the transmitting side can achieve zero phase angle (ZPA). A laboratory prototype with dual independent output currents is built to verify the proposed method. The experimental results agree well with the theoretical analysis.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Xiuxing Yin; Xiaowei Zhao

With the fast development of tidal turbines for sustainable energy generations, reliable and efficient tidal pitch systems are highly demanded. This paper presents a systematic design for a novel tidal pitch system based on hydraulic servo and bevel geared transmission. This system holds the characteristics of compact and triangular structure, making it easy to be installed in a narrow turbine hub. The pitch system dynamics are modelled by taking account of model uncertainties and external disturbances. An uncertainty and disturbance estimator (UDE)-based robust pitch control algorithm is developed to achieve effective pitch angle regulation, disturbance rejection and generator power smoothing. The UDE controller is designed in a composite hierarchical manner that includes an upper level power smoothing controller and a low level pitch angle tracking controller. The performance of the proposed pitch system and the UDE control is demonstrated through extensive simulation studies based on a 600 kW tidal turbine under varying tidal speeds. Compared with the conventional controller, the UDE based pitch controller can achieve more reliable power smoothing and pitch angle tracking with higher accuracy.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Jiadong Lu; Yihua Hu; Guipeng Chen; Zheng Wang; Jinglin Liu

This paper proposes a mutual calibration strategy for multiple current sensors in an electric vehicle motor drive. The motor drive usually consists of three current sensors, i.e., a DC-bus current sensor and two phase current sensors. Due to the aging effect and harsh operating environment, the accuracy uncertainty issue is inevitable in these crucial sensors, which results in poor driving performance. In this paper, the detection voltage injection (DV-Injection) method is proposed for mutual calibration of the aforementioned current sensors. Two opposite basic vectors are set together to detect and eliminate the offset error of the DC-bus current sensor. Then, both the directly measured phase-current values by the phase-current sensors and the indirectly measured values by the DC-bus current sensor are sampled. These values are utilized for mutual calibration of the phase-current sensor offset errors and scaling error differences among all the current sensors. Meanwhile, the DV-Injection process is only applied in the period of calibration process, whereas in the remaining intervals the space vector pulse width modulation (SVPWM) technology is utilized. Finally, the effectiveness of the proposed scheme is verified by simulation study in Matlab/Simulink and experimental results on a 5kW IPMSM motor prototype.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Zhiwei Zhu; Hanheng Du; Rongjing Zhou; Peng Huang; Wule Zhu; Ping Guo

This paper reports on the development of a piezo-actuated nanometric ultra-fast tool servo (NU-FTS) for nanocutting. For motion guidance, a flexure mechanism is especially designed using a novel kind of generalized flexure hinges with the notch profiles described by a rational Bezier curve. Both kinematics and dynamics properties of the mechanism are comprehensively modeled through a novel finite beam modeling method. With this model, the hinge is divided into a set of serially connected beams with constant cross-sections. The equivalent stiffness and lumped moving mass of the mechanism are derived based on the Euler-Bernoulli beam theory. Taking advantage of the structure and performance model, the notch shape as well as the dimensions is optimized to achieve the specified criteria for conducting nanocutting. Performance of the designed mechanism is verified through both finite element analysis and practical testing on a prototype. overall, the NU-FTS is demonstrated to have a stroke of 6 $\mu m$ and 1.2 $\mu m$ for the quasi-static and 10 kHz driving conditions, respectively. Through dynamics inversion based trajectory pre-shaping, a maximum tracking error around 25 nm and 50 nm is obtained for a simple harmonic and a complicated trajectory, respectively.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Xiaoxiao Mi; Yuanyuan Zou; Shaoyuan Li; Hamid Reza Karimi

This paper considers the cooperation control problem for a team of dynamically decoupled agents with resource constraints. A co-design of self-triggered mechanism and distributed model predictive control (DMPC) is proposed to achieve the cooperative objectives while efficiently exploiting communication network. The proposed self-triggered DMPC (ST-DMPC) possesses three important features: (1) The communication cost is explicitly incorporated in the cost function. In this way, the triggering instant and control inputs are simultaneously optimized, and a desired trade-off between control performance and communication cost is achieved. (2) At triggering instants, the first element of the optimal control input sequence along with the current state instead of the whole trajectory is broadcast to neighbors for cooperation, which further reduces communication load. (3) Sufficient conditions on design parameters related to predictive states of neighbor agents are constructed to ensure stability of the overall system. The application of the proposed ST-DMPC to four robot manipulators validates the effectiveness.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Yueshi Guan; Yijie Wang; Wei Wang; Dianguo Xu

This paper proposes a 20MHz low profile DC/DC converter with magnetic-free characteristics based on aircore planar inductors. The switch and diode of the proposed converter operate in soft-switching modes, which significantly reduces the switching loss. Further, the parasitic capacitances are taken as part of corresponding resonant capacitors. A high performance aircore inductor with a variable width and an optimal connecting angle is analyzed. The optimal parameters design method to achieve minimum winding resistance is derived in detail. The resonant driving method is adopted to reduce driving loss in a high frequency condition. A 20MHz prototype is built to verify the feasibility of the proposed converter.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Guan-Ren Chen; Shih-Chin Yang

This paper improves the position sensorless drive by sensing actual machine phase voltages. A high-bandwidth phase voltage measurement is developed for pulse width modulation (PWM) voltage inverters. On the basis, the actual phase voltage is obtained based on the digital integration of PWM voltage using the capture modulator in existing drive microcontrollers (MCU's). Comparing to existing phase voltage measurement, no separated A/D converter and communication hardware are required because PWM pulses are directly measured using MCUs. However for standard machines without neutral points, only line-to-line AC PWM voltages can be measured for the phase voltage reconstruction. Since the capture based on TTL logics receives only digital signals, a preprocess circuit to convert AC PWM line voltages to equivalent digital signals is proposed. This paper clearly explains the voltage sensing hardware using MCU capture modulator. According to experimental results, a 150MHz sampling rate for phase voltage measurement is achieved based on the proposed capture-based voltage measurement. Although the physical limitation of back electromotive force (EMF) estimation still appears, the proposed phase voltage measurement substantially enhances the sensorless drive performance at low speed.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Guangyuan Liu; Tommaso Caldognetto; Paolo Mattavelli; Paolo Magnone

Droop-controlled distributed energy resource converters in dc microgrids usually show low output impedances. When coupled with ac systems, second-order harmonics typically appear on the dc-bus voltage, causing significant harmonic currents at the converters resource side. This paper shows how to reduce such undesired currents by means of notch filters and resonant regulators included in the converters control loops. The main characteristics of these techniques in terms of harmonic attenuation and stability are systematically investigated. In particular, it is shown that the voltage control-loop bandwidth is limited to be below twice the line frequency to avoid instability. Then, a modified notch filter and a modified resonant regulator are proposed, allowing to remove the constraint on the voltage loop bandwidth. The resulting methods (i.e., the notch filter, the resonant regulator, and their corresponding modified versions) are evaluated in terms of output impedance and stability. Experimental results from a dc microgrid prototype composed of three dc-dc converters and one dc-ac converter, all with a rated power of 5 k W, are reported.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Amad Ud Din; Jae-Hun Lee; Nguyen Xuan Hieu; Jong-Wook Lee

A ultrahigh-frequency (UHF) band passive RFID tag integrated circuit (IC) supporting both Gen-2 and visible RFID modes is proposed. Two sources can be used to provide modulated data for the dual-mode tag IC: a radio frequency (RF) or visible light (VL) source. When a modulated RF signal is used, the tag IC operates in Electronic Product Code (EPC) Generation-2 (Gen-2) mode. In the visible RFID mode, modulated VL delivers data and continuous-wave RF provides power for the tag IC. In both modes, power is provided by RF. For the tag IC, a self-calibrating clock generator robust to process variation is proposed. Without a battery, the clock generator has an accuracy of ±4% by continuously calibrating its frequency using downlink pulse-interval encoding (PIE) symbols from a reader. In the core of the clock generator, there is a new PIE decoder that reliably distinguishes between data-0 and data-1 under process, voltage, and temperature (PVT) variations. The tag IC has been fabricated using a 0.18 μm CMOS process with a chip area of 1.4 ~ 1.7 mm2. The power consumption of the tag IC is 64 μW. Experiments are conducted using a photodiode in the visible RFID mode. With 0.34 mW power from a VL source, the tag IC shows successful detection of VL signal at distances up to 15 m.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Yanfeng Chen; Wenxun Xiao; Zhipeng Guan; Bo Zhang; Dongyuan Qiu; Meiyu Wu

Magnetic resonant wireless power transfer (WPT) system with class E inverter has wide application in mid-range power transmission, especially for several-megahertz(MHz) scenario. However, it is cumbersome for the existing modeling and analysis methods to obtain the analytical solution to the system variables, which limits the evaluation of system characteristic. This paper proposes a nonlinear mathematical model for WPT system with class E inverter. The Equivalent Small Parameter Method (ESPM) is first adopted to solve the proposed six-order nonlinear model, and symbolic-form steady-state periodic solutions are yielded. During the whole solving process only three iteration steps are needed for the proposed method. Compared with other existing modeling and analysis methods, the symbolic periodic results acquired by the ESPM exhibit sufficient accuracy by virtue of the combination of more higher harmonics. Meanwhile, the calculation complexity is simplified remarkably. Simulation and available experiments validate the effectiveness and accuracy of the proposed method.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Haitao Hu; Pengyu Pan; Yitong Song; Zheng-You He

The accurate information of the wide-bandwidth impedance versus frequency is urgently needed for evaluating the system resonances, instabilities and operations of the railway traction power system (TPS), and to avoid/control the harmonic resonance and oscillation issues. As the system topology and detailed parameters of the TPS are not fully known even timely varying, we have to obtain the detailed wide-bandwidth impedance information through exciting harmonic disturbance into the system and then calculating the response information. Therefore, a controlled wide-bandwidth impedance measurement approach is presented here. In which, a butterfly-type disturbance circuit and chirp-pulse width modulation (PWM) signal model are cooperated to generate the desired controlled-bandwidth harmonics with a high aggregation as well as the average amplitude. Impedance measurement results of the proposed approach have been validated through both simulation and experiment. Considering the measured errors, the proposed method is efficient in testing the wide-bandwidth impedance of the single-phase railway traction system.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Peng Liu; Changsong Chen; Shanxu Duan

Compared with the conventional two-level dual-active-bridge (DAB) dc-dc converter, the three-level DAB converter could operate with lower voltage rated switching devices and provide more control degrees of freedom, which enhances the control flexibility. This paper proposes a modulation strategy with five control degrees of freedom. In the previous work with multi control degrees, the optimization strategies for efficiency or inductor current minimization are investigated, however, these strategies all need detailed mode analysis and complex mathematical optimization tools to obtain the optimal duty cycles. In this paper, an optimization strategy for the root-mean-square (RMS) value of the inductor current is proposed. This method extracts the fundamental and 3rd harmonic components from the high-frequency voltages on both sides, and adjusts the amplitude of the bridge voltages by the vector diagram to obtain the optimal duty cycles. The inductor current can be reduced significantly at light loads with the proposed strategy, so the efficiency of the converter can be improved. Moreover, the optimization process does not need the detailed operation analysis of the converter, nor does it require the complex mathematical optimization tools. Finally, the performance of the three-level DAB and the optimization strategy are verified by the experimental results.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Masahiro Sato; Masayoshi Toda

This paper proposes adaptive algorithms of gain tuning for Kalman filters and switching Kalman and H∞filters for discrete systems. Both of the gain tuning and switching rely on square means of innovations. The paper also provides stability analyses on time-varying Kalman filters and derives a sufficient condition for their asymptotic stability, on which our gain-tuning algorithm is based. It should be noted that the stability condition is available for even nonstabilizable systems having their uncontrollable poles on the unit circle. To illustrate those algorithms, we perform simulations using a harmonic oscillator model which is nonstabilizable and has its poles on the unit circle. Further, we apply the algorithms to estimation of ship oscillation, particularly, with time-varying frequencies by simulations and model experiments. Consequently, all the results of stability analyses, simulations, and experiments have convinced that the algorithms are solid and effective.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Arun Kumar Paul

Metallic joints are created in multivariable GMAW process by maintaining a balance between the quantum of heat generated and the feeding rate of electrode metal to the weld gap. The wire feeding control is often independently handled. The wire feeder unit should be simple, low cost and capable of producing accurate speed. Arc welding controllers are often kept in clumsy conditions and the wire feeder unit is located close to the welder, could be much away from the controller. To reduce interconnections separate sensing element for speed feedback should be avoided. Due to their negligible electrical and mechanical time constant, the pancake type PMDC motor is suitable for wire feeding where sensing of back-emf for feedback is easy. When high frequency PWM controller is used the sensing of back-emf gets complicated. This article explores the constraints on the choice of PWM frequency along with its maximum pulse width for different type of DC motors. It further elaborates comparatively on the choice of suitable control function for generating accurate speed control of wire feeding using back-emf as feedback. Finally, the article also details the experimental results using the proposed control function.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Sergio Busquets-Monge; Alber Filba-Martinez; Salvador Alepuz; Joan Nicolas-Apruzzese; Adria Luque; Alfonso Conesa Roca; Josep Bordonau

This paper studies a multilevel multiphase dc-ac conversion system configured by a neutral-point-clamped converter fed by multiple battery packs connected in series. A virtual-vector modulation is selected and a state-of-charge (SoC) balancing control is designed to be able to employ the full battery bank capacity, even under different battery initial SoC values or different battery nominal capacities. The SoC balancing among battery packs is accomplished through the multilevel converter operation in a lossless manner, by simply distributing the dc-to-ac power flow among the batteries according to their SoC. A simple average system model is also presented, which allows performing very fast system simulations over long periods of time and serves as a convenient tool to tune the compensator parameters. The satisfactory performance of the proposed system configuration and control, which can be applied with any number of levels and phases, has been verified through simulations and experiments in a four-level three-phase dc-ac converter fed by three Lithium-ion battery packs. The results prove the feasibility and advantages of the proposed system configuration, which can be used to implement conversion systems with different specifications combining several instances of a standard battery pack and a standard power semiconductor device.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Hui Chen; Xinke Wu; Shuai Shao

A current sharing method for an interleaved high frequency LLC converter with partial energy processing is presented in this paper. A small transformer and an auxiliary low power dc-dc converter are added in each phase and the current sharing between phases is achieved by controlling the duty cycle of the auxiliary converter. Only partial energy is processed by the auxiliary converter, hence the power losses of the added auxiliary converters are minimized and overall high efficiency is maintained. By transforming the current sharing of the resonant converter into PWM control of a dc-dc converter, the proposed method is simple to implement and easy to extend to multiple phases. The frequency of the auxiliary converter is independent of the main LLC, so the LLC can operate at a fixed switching frequency and duty cycle, and it is suitable for high frequency applications. The operating principle, design considerations and the control schemes are presented and a 1MHz two-phase interleaved LLC prototype was built to verify the theoretical analysis.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Teng Wang; Guoliang Lu; Peng Yan

The key function of rotating machine condition monitoring is to detect structural changes during machine operations.This paper presents a novel statistical time-frequency analysis method for this purpose. In particular, frequency spectrum is extracted from the machine condition signals based on periodogram estimation. Undirected weighted graph (UWG) is then constructed from the resulting periodograms, where the so-called median graph is introduced and adopted to describe the normal machine status. Statistical analysis is performed to investigate newly observed data with respect to the median graph for change decision making. The proposed method has been applied to three different engineering applications to evaluate its effectiveness: load condition monitoring, early bearing failure detection and speed condition monitoring. The results demonstrate significant performance improvement than state-of-the-art methods reported in the literature, indicating its good potentials in engineering applications.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Kapil Upamanyu; G Narayanan

The accuracy of a power hardware in loop (PHIL) simulation is influenced by factors including dynamics of the power amplifier (PA) and discretization of the real-time simulated part of the system. Open-loop voltage source inverter (VSI) without output filter is demonstrated to be a good choice for power amplification in terms of cost, size, design effort, bandwidth and accuracy when the load on the PA is significantly inductive. Open-loop VSI based PA is shown to be accurate in emulating a synchronous generator, including the fast transients in the excitation control system. The discretization effects of the real-time simulator (RTS) are captured effectively by the discrete-time (DT) modelling approach proposed in the paper. The DT model is shown to replicate fast transients in the PHIL simulation better than the existing continuous-time based model. Stability of the PHIL simulation of a benchmark circuit is analyzed using the proposed DT modelling. The stability analysis is validated through simulations and experiments. The stability limits derived, based on the proposed analysis, are capable of suggesting maximum and minimum values of certain circuit parameters as required for stability.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Seung-Hwan Lee; Myung-Yong Kim; Byung-Song Lee; Jaehong Lee

Steel-reinforced concrete has been widely used in the construction of railways because of its robustness and low maintenance cost. This study focuses on the analysis of unwanted losses in a reinforced concrete track when a high-power on-line wireless power transfer system is installed on it. Induced dielectric loss in the concrete, and eddy-current and hysteresis losses in the reinforcing steel bar were calculated using analytic equations and finite element analysis. Among the three sources of loss, a dominant one was identified in the first three sections of this paper. It was shown that the dielectric loss in the concrete and the hysteresis loss in the reinforcing bar did not have a critical impact on the efficiency. However, it was found that the eddy-current loss of the reinforcing bar was dominant over the other two losses. Furthermore, the eddy-current loss of the reinforcing bar overwhelmed the Ohmic loss of a transmitter coil if the transmitter coil was not located in a proper position on the concrete track. The theoretical results were evaluated experimentally using a 7-m-long test bed. When the transmitter coil was located 0.14 m above the reinforcing bar, the measured eddy-current loss of the steel bar was 3 kW while the Ohmic loss of the transmitter coil was 1.5 kW. As the distance between the transmitter coil and the steel bar increased, the eddy-current loss of the bar decreased rapidly. From the simulation and the experimental evaluation of the loss, guidelines for installing a transmitter coil on a reinforcing bar for an in-motion wireless power transfer system were suggested.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Kai Jiang; Fengjun Yan; Hui Zhang

Selective catalytic reduction (SCR) systems have been widely used to meet the emission regulations and two-cell SCR systems have shown the advantages of high $\rm NO_{x}$ conversion efficiency and low $\rm NH_{3}$ slip simultaneously. However, it is noteworthy that the catalyst performance of SCR device would degrade over the service time gradually. If the performance degrading is not well compensated, the $\rm NO_{x}$ conversion efficiency would reduce significantly. Different from detecting the aging issue in the laboratory, a practical method is to design an observer to estimate the aging factor online such that the urea injection can be modified accordingly. In this work, we aim to construct an aging-factor observer for two-cell SCR systems. In order to reduce the algorithm computational load and guarantee the implementation performance, we propose a dual time-scale algorithm based on two-cell SCR model and unscented Kalman filter (UKF). There is a fast time scale and a slow time scale in the algorithm. Two simulation studies of constant aging factor and time-varying aging factor are investigated in the simulation environment of MATLAB/SIMULINK. The simulation results indicate that the proposed dual time-scale observer works well under different conditions and the calculational load is reduced significantly.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Hui Yang; Heyun Lin; Z.Q. Zhu; Shukang Lyu; Yangyang Liu

This paper proposes a novel flux reversal permanent magnet (FRPM) machine with asymmetric-stator-pole (ASP) configuration. Different from the conventional FRPM machine with uniform “NS-NS-NS” PM sequence, the proposed ASP-FRPM machine is characterized by a “NSN-S-NSN” magnet arrangement. Hence, the interpolar flux leakage is significantly reduced with the developed design, which can improve the torque capability. The machine topologies, features and operating principle are introduced, respectively. A simplified magnetic circuit model is established to reveal the underlying flux leakage reduction mechanism of the ASP design, and the rotor pole number is analytically optimized as well. The design parameters are then globally optimized so as to improve the torque quality. In addition, the electromagnetic characteristics of the ASP- and conventional FRPM machines are compared. Finally, experiments have been carried out to validate the theoretical results.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2019-02-05
Manel Hammami; Gabriele Grandi

This paper deals with the analysis of the input dc-link voltage ripple in multilevel inverter based on H-bridge and level doubling network (LDN). The LDN is basically a half-bridge fed by a floating capacitor, with voltage self-balancing capability, recalling the concept of a flying capacitor configuration. The amplitude of the LDN voltage ripple is analytically determined considering both the low-order and the switching harmonic components. In particular, peak-to-peak distributions of voltage ripples over the fundamental period are analytically determined, making possible the design of dc-link capacitor relying only on the dc-voltage ripple requirements. The case study makes reference to negligible switching ripple in the output current. It well represents either grid connection or passive load having almost sinusoidal currents. Numerical simulations carried out by Matlab/Simulink and a complete set of experimental verifications are given to confirm the theoretical developments.

更新日期：2019-02-06
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-24
Jiangfeng Wang; Hongfei Wu; Tianyu Yang; Li Zhang; Yan Xing

A bidirectional three-phase dc–ac converter with embedded dc–dc converter for bidirectional storage interface is proposed in this paper. With the help of the embedded dc–dc converter, the voltage of the storage battery can vary in a wide range. To minimize the power rating and power losses of the embedded dc–dc converter, a simple carrier-based pulsewidth modulation (PWM) strategy with zero-sequence injection is proposed. By adopting the proposed PWM strategy, only a small ratio of total power needs to be processed by the embedded dc–dc converter, while most of the power is only processed by the three-phase dc–ac stage within a single conversion stage. As a result, quasi single-stage power conversion is achieved to improve the conversion efficiency of the overall dc–ac power system. Principles, characteristics, and implementations of the proposed three-phase dc–ac converter and its PWM strategy are analyzed in detail. The feasibility and effectiveness of the proposed solutions are verified with experimental results.

更新日期：2019-02-05
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-10
Osman Kukrer; Sertac Bayhan; Hasan Komurcugil

In this paper, a model-based current control strategy with virtual time constant is proposed for three-phase grid-connected LCL -filtered voltage source inverters. The proposed control strategy is based on controlling the inverter currents in the rotating dq frame by using current-oriented proportional-integral (PI) controllers rather than voltage-oriented PI. The PI controllers determine the inverter current references in the d - and q -axes by regulating the grid current. It is shown that the proposed strategy decouples the inverter current from other variables provided that the inverter-side inductance and its resistance values used in the control variable match the actual values in the system. In addition, the virtual time constant is introduced in the control variables to offer flexibility for adjusting the inverter current dynamics as desired. Moreover, the integral gain of PI controller has the ability to keep the LCL -resonance peak below 0 dB. Unlike the existing methods, the proposed strategy does not require a dedicated active damping. Computer simulations and experimental studies show that the proposed control strategy exhibits a good performance in achieving fast dynamic response and sinusoidal grid current with low THD under balanced, unbalanced, and distorted grid conditions.

更新日期：2019-02-05
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09

A trinary multilevel converter uses a few heterogeneous H-bridge submodules (SMs) to synthesize an output voltage with multiple levels. Two major limitations of this converter are that it needs multiple dc sources and it cannot operate under pulsewidth modulation (PWM). This paper addresses these limitations by adding a low-voltage H-bridge SM to this converter and proposing a new switching algorithm. The resulting PWM-based asymmetric cascaded H-bridge converter uses only one dc source and synthesizes a high-quality output voltage. This improved converter can be a potential choice for real and reactive power support in power system applications. This paper also proposes methods for stability analysis and design of this converter. Experimental case studies evaluate the performance of the proposed converter for both standalone and grid-connected modes of operation.

更新日期：2019-02-05
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-03
Kapil Shukla; Ramkrishan Maheshwari

Two parallel interleaved two-level (2L) three-phase voltage source inverters (VSIs) can be analyzed as a single three-level (3L) VSI. A generalized carrier-based method is proposed in this paper for implementing different 3L pulsewidth modulation (PWM) techniques using two parallel interleaved 2L VSIs. The proposed method modifies the given three-phase reference signals of 3L VSI for implementation of the PWM technique using two parallel interleaved 2L VSIs. The influence of nonidealities on the equivalent 3L PWM switching sequences is also discussed. To overcome the effect of nonidealities, a new modified discontinuous PWM technique (MDPWM1) is proposed. The analysis of different performance indices is carried out for different 3L PWM techniques, and the key advantages of different PWM techniques are identified. Simulation and experimental results are also presented.

更新日期：2019-02-05
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15
Linnan Sun; Zhuoran Zhang; Li Yu; Xiangpei Gu

A new hybrid excitation brushless dc generator (HEBLDCG) consisting of structure-parallel permanent magnet machine part and flux modulation machine part is proposed in this paper. Based on the flux modulation effect, the permanent magnet machine and flux modulation machine parts, which have different operating principles, can be combined. In addition, the proposed HEBLDCG features a lower short-circuit current by regulating field current, which increases reliability. The operating modes of flux modulation machine part are fully analyzed under different conditions. Changes in the phase shift factor of the permanent magnet machine part caused by the operating modes of the flux modulation machine part are investigated. Further, the proposed HEBLDCG features constant voltage output at a wide range of speeds. Finally, a prototype HEBLDCG is designed and manufactured. The experimental data agree with the simulated data. Loss breakdown is analyzed and efficiency is measured. An HEBLDCG with a reliable diode rectifier is promising for application in on-board dc power generation systems.

更新日期：2019-02-05
• IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-03
Weijia Shi; Bo Zhao; Xue Qi; Yiran Wang; Hui Zhao; Weishan Chen; Jiubin Tan

This paper presents a high-efficiency inverter with the aid of the soft-switching technology, which is accomplished by the resonance of the in-series inductance with the snubber capacitance. The equivalent circuit of the quarter-phase ultrasonic motor is initially deduced, based on which the topology along with the operations of the novel inverter is subsequently presented. The configuration of the new quarter-phase inverter shows its uniqueness in terms of the shared arms and the especially designed snubber capacitance in comparison with the existing inverters. The circuit analysis infers that the dead time of the inverter is the key factor to arrive at the zero-voltage-switching or the zero-current-switching operations. Experimental measurements have demonstrated that the efficiency of the whole drive increases by a factor of 1.25 after replacing the traditional inverter with the proposed one. It should also be noted that the proposed inverter in association with the design method of the dead time not only can work for the quarter-phase ultrasonic motor, but also can be applicable for other kinds of quarter-phase devices. The soft-switching operations are achieved in the quarter-phase inverter for the first time, whose amplitudes of the output voltage and switching frequency are not required to be constant any more.

更新日期：2019-02-05
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.