MUSIC-like Algorithm for Source Localization in Electrical Impedance Tomography IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : Narong Borijindargoon; Boon-Poh Ng; Susanto Rahardja
In electrical impedance tomography (EIT), the noise amplified solution caused during matrix inversion can be avoided with non-parametric spectral based estimation when the conductivity variation is bounded and spatially sparse. Among many spectral based algorithms used in direction-of-arrival (DOA) estimation, an algorithm called multiple signal classification (MUSIC) is one of the most well-known that has super resolution performance. However, its dependency on the model order estimation can lead to performance degradation especially for quasi-static environment like EIT application and this is due to source location changes and conductivity variation. In this paper, the relationship between source position, conductivity variation, ill-conditioned array manifold and eigenvalues of the covariance matrix are explored. An algorithm called MUSIClike which has high resolution performance comparable to MUSIC is then proposed for EIT application. It is formulated under the beamforming framework, and therefore does not require an estimation of model order from the covariance matrix. Simulation results show that the proposed method is capable of obtaining high resolution performance under various noise levels. An 8-electrode EIT system prototype was built using the proposed method, and experimental results confirm the high resolution performance capability of the proposed method.
Dynamic distributed monitoring strategy for large-scale nonstationary processes subject to frequently varying conditions under closed-loop control IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-17 Chunhui Zhao; He Sun
Large-scale processes under closed-loop control are commonly subjected to frequently varying conditions due to load changes or other causes, resulting in typical nonstationary characteristics. For closed-loop control processes, the normal changes in operation conditions may distort the static and dynamic variations in a different way from real faults. Traditional monitoring strategies cannot distinguish between normal operation changes and real process faults because they only monitor the static information without considering the dynamic variations. In the present study, a dynamic distributed monitoring strategy is proposed to separate the dynamic variations from the steady states, and concurrently, monitor them to distinguish changes in the normal operating condition and real faults for large-scale nonstationary processes under closed-loop control. First, large-scale nonstationary process variables are decomposed into different blocks to mine the local information. Second, the static and dynamic equilibrium relations are separated by probing into the cointegration analysis solution in each block. Third, the concurrent monitoring models are constructed to supervise both the steady variations and their dynamic counterparts for each block. Finally, the local monitoring results are combined by Bayesian inference to obtain global results. The feasibility and performance of the proposed method are illustrated with a real industrial process, which is a 1000-MW ultra-supercritical thermal power unit.
A Sampled-Data Approach to Nonlinear ESO-Based Active Disturbance Rejection Control for Pneumatic Muscle Actuator Systems with Actuator Saturations IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-17 Yuan Yuan; Yang Yu; Zidong Wang; Lei Guo
In this paper, an active disturbance rejection control (ADRC) scheme with a nonlinear sampled-data extended state observer (NSESO) is proposed for a pneumatic muscle actuator (PMA) system. The phenomenon of the actuator saturation is taken into account in the design procedure. The NSESO is utilized to estimate the so-called total disturbance that reflects the aggregated impacts of unmodeled nonlinearities and disturbances. Then, an NSESO-based composite control strategy is designed where the estimates provided by the designed NSESO serves as the compensation to eliminate the total disturbance. Finally, a number of practical experiments on the PMA systems are conducted to verify the validity and applicability of the proposed design method.
Circular Formation Algorithms for Multiple Nonholonomic Mobile Robots: An Optimization-Based Approach IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Jiahu Qin; Shuai Wang; Yu Kang; Qingchen Liu
This paper revisits the circular formation control problem proposed in , for multiple nonholonomic mobile robots with non-identical constant forward speeds. Specifically, we study two types of circular formations: 1) a circular motion with synchronized/balanced phase configuration; 2) a concentric circular formation with both circular orbits control and phase synchronization/balancing. Existing works on the above problems utilize fixed-gain control input, which increases the workload of the engineers for selecting favourable algorithm parameters. To reduce the corresponding workload, we study the above problems from a new perspective by utilizing optimization methods, based on which two variable-gain control algorithms are proposed such that much greater flexibility on the selection of algorithm parameters is acquired. The global convergence properties of the proposed algorithms are analyzed under some mild assumptions on the proposed objective functions. Both simulations and field experiments are presented to validate the effectiveness of the proposed formation algorithms.
Nonlinear Parity-Time-Symmetric Model for Constant Efficiency Wireless Power Transfer: Application to a Drone-in-Flight Wireless Charging Platform IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Jiali Zhou; Bo Zhang; Wenxun Xiao; Dongyuan Qiu; Yanfeng Chen
A major challenge for practical wireless power transfer (WPT) applications is to attain stable power transfer with high and constant transfer efficiency under a dynamic change of coupling condition. In order to address the issue, this paper proposes a novel nonlinear parity-time-symmetric (PT) model, wherein the nonlinear saturable gain is provided by a self-oscillating controlled inverter. In this paper, the transfer performance and stability criterion of the nonlinear PT-based WPT system are analyzed based on the coupled-mode theory (CMT). The theoretical analysis shows that the proposed system automatically achieves constant output power with constant transfer efficiency against the variation of coupling coefficient. Moreover, based on the gain saturation mechanism, the control strategy for the inverter only need detect the current in the transmitter, which eliminates auxiliary circuits of wireless communication for feedback control from the receiver. As a case study of dynamic charging, a drone-in-flight wireless charging platform is improved by applying the nonlinear PT-symmetric model. Experimental results show that, when the flying drone hovers in a confined 3-D volume of space above the WPT platform, a stable output power is maintained with approximately constant transfer efficiency of 93.6%.
Incremental Updating Multi-Robot Formation Using Nonlinear Model Predictive Control Method with General Projection Neural Network IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Hanzhen Xiao; C. L. Philip Chen
For controlling the multi-robot formation with joining robots, an incremental centralized formation system is developed 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 new robot joining during formation process. Then a NMPC approach is developed to reformulating the formation system into a convex nonlinear minimization problem, which can further be 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 multi-robot formation are performed to verify the effectiveness of this method.
Causal Markov Elman Network for Load Forecasting in Multi Network Systems IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Lalitha Madhavi Konila Sriram; Mostafa Gilanifar; Yuxun Zhou; Eren Erman Ozguven; Reza Arghandeh
This paper proposes a novel causality analysis approach called the Causal Markov Elman Network (CMEN) to characterize the interdependency among heterogeneous time-series in multi-network systems. The CMEN performance, which comprises of inputs filtered by Markov property, successfully characterizes various multivariate dependencies in an urban environment. The paper also proposes a novel hypothesis of characterizing joint information between interconnected systems such as electricity and transportation networks. The proposed methodology and the hypotheses are then validated by Information Theory distance-based metrics. For cross-validation, the CMEN is applied to the electricity load forecasting problem using actual data from the City of Tallahassee, Florida.
Integral-Sliding-Mode Braking Control for Connected Vehicle Platoon: Theory and Application IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Yongfu Li; Chuancong Tang; Srinivas Peeta; Yibing Wang
This paper proposes a distributed integral- sliding-mode (ISM) control strategy for cooperative braking control of a connected vehicle platoon with a focus on the car-following interactions between vehicles. In particular, a linear controller considering the position and velocity of the lead vehicle as well as the braking force is proposed for the leader; while a constant time headway policy based ISM controller incorporating the car-following interactions, the spacing error, velocity difference, and external disturbances is developed for the followers. In addition, the convergence for the ISM controller is rigorously analyzed using the Lyapunov technique. Further, the string stability of the platoon is analyzed using the transfer function method. Finally, extensive analyses are conducted using numerical and field experiments. Results verify the effectiveness of the proposed control strategy with respect to the position, velocity, deceleration, and spacing error profiles.
Development and Analysis of a New Hybrid Excitation Brushless DC Generator with Flux Modulation Effect 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. A HEBLDCG with a reliable diode rectifier is promising for application in onboard DC power generation systems.
Synchronization Control in the Cable Space for Cable-Driven Parallel Robots 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 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 (CS) 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 3-DOF CDPR, and the experiments are compared with the traditional augmented PD (APD) 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.
Stability Analysis of PV Generators with Consideration of P&O Based Power Control IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Yanghong Xia; Wei Wei; Miao Yu; Peng Wang
The photovoltaic (PV) generators are continuously increasing in recent years, whose power is usually controlled through the perturbation and observation (P&O) method. In essence, the P&O method is nonlinear and discontinuous. Hence, the conventional small-signal stability analysis is unsuitable anymore when the influence of the P&O based power control is considered. Focusing on this problem, this paper adopts the nonlinear describing function (DF) method to conduct the accurate stability analysis of PV generators with consideration of P&O based power control. The detailed procedures about the DF method are introduced, then the related influence factors like perturbation size, filters and so on are analyzed quantitatively. Furthermore, the comparison with the conventional stability analysis methods is made, which suggests that the DF method can effectively enhance the accuracy of the stability analysis. All the conclusions are verified by the real-time hardware-in-loop (HIL) tests.
Time Series Classification with Multivariate Convolutional Neural Network IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Chien-Liang Liu; Wen-Hoar Hsaio; Yao-Chung Tu
Time series classification is an important research topic in machine learning and data mining communities, since time series data exists in many application domains. Recent studies have shown that machine learning algorithms could benefit from good feature representation, explaining why deep learning has achieved breakthrough performance in many tasks. In deep learning, the convolutional neural network (CNN) is one of the most well-known approaches, since it incorporates feature representation and classification task in a unified network architecture. Although CNN has been successfully applied to image and text domains, it is still a challenge to apply CNN to time series data. This work proposes a tensor scheme along with a novel deep learning architecture called multivariate convolutional neural network (MVCNN) for time series classification, in which the proposed architecture considers multivariate and lag-features characteristics. We evaluate our proposed method with prognostics and health management (PHM) 2015 challenge data, and compare with several algorithms. The experimental results indicate that the proposed method outperforms the other alternatives using the prediction score, which is the evaluation metric used by the PHM Society 2015 Data Challenge. Besides performance evaluation, we provide detailed analysis about the proposed method.
A Potential Game Approach to Distributed Operational Optimization for Microgrid Energy Management with Renewable Energy and Demand Response IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Jun Zeng; Qiaoqiao Wang; Junfeng Liu; Jianlong Chen; Haoyong Chen
Microgrid is considered as one of the most effective ways to demonstrate and evaluate the challenges of IoE. Advanced operational optimization in MEMS is expected to be scalable to accommodate various participants and support their plug-and-play (PNP) as well as optimize energy utilization of the system before connecting to the power grid as a whole. This paper presents a fully distributed operational optimization for MEMS with high penetration of renewable and demand response. The difficulties involved in a fully distributed manner are the contradictions between intelligent individual interest seeking and overall importance of the whole microgrid and the solution of coupled objective functions with spatially and temporally coupled constraints. This paper formulates the process of a potential game combing with a penalty function and best strategy response iterative method. The framework of potential game ensures three significant points: 1) no need of any central coordinator during the process of execution; 2) consistency between the individual rationality and the overall importance of whole microgrid; and 3) both the optimality and convergence are obtained. Simulations are conducted for a typical microgrid consisting of photovoltaic arrays, wind turbines, diesel engines, batteries and loads. The results show the proposed algorithm is effective and feasible.
A New Modulation Strategy to Reduce Common Mode Current of Indirect Matrix Converter IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Mei Su; Jianheng Lin; Yao Sun; Shiming Xie
This letter presents a new space vector modulation (SVM) strategy adopting new zero vectors to achieve common mode current (CMC) reduction for indirect matrix converter (IMC). By substituting conventional zero vectors by new zero vectors, the impedance of common mode loop increases, which contributes to CMC reduction. Thus, the IMC system with proposed method alleviates the adverse effects of CMC for AC drives. Moreover, additional hardware and complex commutation process are not required. Experiments are conducted to verify the effectiveness of the proposed method.
A methodology to remove Stator Skew in Small-Medium Size Synchronous Generators via innovative damper cage designs IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Stefano Nuzzo; Paolo Bolognesi; Gaurang Vakil; Daniel Fallows; Chris Gerada; Neil L. Brown; Michael Galea
This paper proposes and investigates an innovative methodology that can have a significant impact on the market potential of wound field, small-medium size synchronous generators. The technique proposed here is aimed at removing the need for the traditional stator skewing that is so commonly used in synchronous generators to achieve acceptable values of voltage total harmonic distortion. To do this, a non-standard damper cage configuration is proposed that comprises modulation of the damper bars' positioning. An off-the-shelf, 400kVA generator is used as a benchmark machine. Its rotor is optimized and modified according to the proposed technique. The results of the final machine are then compared to the benchmark machine highlighting the excellent advantages that can be achieved through this technique. A full-scale prototype of the modified generator is then built to experimentally validate the concept. Finally, a detailed analysis on all the performance aspects of the prototype is done, to guarantee that the proposed technique has no negative impact whatsoever on the generator's performance.
Discrete-Time Sliding-Mode Control with Enhanced Power Reaching Law IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Haifeng Ma; Yangmin Li; Zhenhua Xiong
This paper presents the design, analysis, and verification of a novel reaching law for discrete-time sliding-mode control. The control gains of the reaching law are automatically regulated by the power function and the exponential term that dynamically adapts to the variation of the switching function. The reaching law also employs the perturbation estimation and the difference function to redefine the change rate as the second-order difference of the uncertainties. Compared with previous methods, the proposed reaching law has the capability to amend the control gains in a wise manner, further mitigate chattering and guarantee smaller width of the quasi-sliding-mode domain (QSMD). In order to describe the system dynamics in the reaching phase and the sliding phase with respect to control gain values, both the decrement band and the QSMD (ultimate band) of the proposed reaching law are theoretically analyzed. The reaching steps for the switching function to converge toward the sliding surface are also obtained. The effectiveness of the proposed method is verified through numerical simulations and experimental investigations on a piezoelectric actuator.
SPWM-Based Direct Digital Control with Average-Voltage Model and D-Σ Process for Paralleled 3ø3W Grid-Connected Converters to Reduce Circulating Currents IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Tsai-Fu Wu; Ling-Chia Yu; Yen-Hsiang Huang; Ying-Yi Jhang; Bo-Tang Zeng
This paper presents a sinusoidal pulse-width modulation (SPWM) based direct digital control with average-voltage model (AVM) and division-summation (D-Σ) process for paralleled three-phase three-wire (3ø3W) grid-connected converters to reduce circulating currents. With the direct digital control, plant of each single-phase converter can be derived directly, and a controller is then designed to cover the variation effects of filter inductance and grid-voltage. Based on SPWM and AVM over a switching cycle, each 3ø3W converter can be decomposed into three single-phase converters and each converter is controlled individually to track its sinusoidal reference current tightly, reducing circulating currents significantly. Equal current sharing is therefore also achieved. The control laws for achieving grid connection are derived in detail. In the design and implementation, the inductances corresponding to various inductor currents were measured offline and stored in the controller for scheduling loop gain cycle by cycle. Experimental and simulated results from a three-converter system have confirmed the analysis and discussion of the proposed control approaches.
Switching Fault Ride-Through of GSCs Via Observer-Based Bang-Bang Funnel Control IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Yang Liu; Kaishun Xiahou; Xu Lin; Qinghua Wu
This letter proposes a switching fault ride-through controller (SFRTC) for the grid-side converter (GSC) of permanent magnetic synchronous generator-based wind turbines (PMSGWTs). The SFRTC switches between an observer-based bang-bang funnel controller (OBFC) and a vector controller (VC) via a state-dependent switching scheme. The design of OBFC does not rely on accurate system information, and it works with the estimates of high-order dynamics of system outputs obtained with a high-gain observer. The fault ride-through (FRT) control performance of SFRTC was studied with hardware-in-the-loop experiments.
Two-time-scale redesign for anti-lock braking systems of ground vehicles IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-15 Weichao Sun; Jinhua Zhang; Zhiyuan Liu
Anti-lock braking system (ABS) is one of the most effective active safety control systems for ground vehicles, since it can keep the rotational wheel from locking, and consequently guarantee the braking safety and handling stability. There have been a variety of ABS control schemes proposed by many researchers. However, most results employ sundry tire-road friction models, the alleged$\mu\ - \lambda $curves (μ is tire-road friction coefficient, while λ is tire slip ratio, which is mathematically defined with equation (4)), making the ABS controller extremely complicated for the highly non-linear characteristics of$\mu\ - \lambda $relationship. Furthermore, the priori knowledge of road conditions for these ABS controllers restricts their practicability. To circumvent these problems, a two-time-scale ABS control scheme is proposed in this paper, without considering the intricate$\mu\ - \lambda $relationship, making the priori knowledge of road condition no longer a prerequisite, thus the designed ABS controller is rather simple. More than that, a modified fast-time-scale estimator is involved to estimate the road condition, which is significant in vehicle active dynamics control. The effectiveness of the proposed ABS controller is verified via numerical simulations and CarSim-Matlab co-simulations.
A Novel Cross-Capacitive Sensor for Non-Contact Micro Droplet Detection IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-14 Zubair Hassan Zargar; Tarikul Islam
A novel capacitive sensor for non-contact micro droplet detection has been developed and tested successfully. For an accurate and highly repeatable droplet detection, the sensor makes use of a cross-capacitive structure which is an extension of the Thompson and Lampard theorem. The sensor consists of four identical copper electrodes with infinitesimally small gaps etched out of double-sided copper cladded polyimide substrate by screen printing and chemical etching process. The sensor prototype has been tested for different sizes of the droplets as well as the droplets from liquids having different dielectric constants and conductivities. The response characteristics of the presented sensor are very accurate, significant, fast and highly repeatable (± 0.13%) and drift free. The achieved characteristics of the presented sensor are suitable for employing it for the non-contact micro droplet detection.
Soft Switching High Step-Up/Down Bidirectional DC-DC Converter IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-14 Zahra Hosseinzadeh; Navid Molavi; Hosein Farzanehfard
A non-isolated bidirectional DC-DC converter with high voltage gain, low voltage stress, low component count and soft switching features is presented in this paper. In this topology, coupled inductors and voltage multiplier cells are merged to achieve high step-up/down voltage gain. Also, due to using active clamp circuits, the voltage stress of power switches is relatively low and low voltage switches with low on-resistance can be employed to reduce the conduction losses. Furthermore, zero-voltage-switching is accomplished in both high step-up and high step-down modes for all power switches and due to zero current switching operation of all antiparallel diodes, the reverse recovery losses is reduced. In order to verify the theoretical analysis and the converter performance, a 200 W prototype circuit of the proposed converter is implemented in laboratory.
Chance-Constrained Optimization for Multi Energy Hub Systems in a Smart City IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-14 Da Huo; Chenghong Gu; Kang Ma; Wei Wei; Yue Xiang; Simon Le Blond
The Energy Hub is a powerful conceptualisation of how to acquire, convert, and distribute energy resources in the smart city. However, uncertainties such as intermittent renewable energy injection present challenges to energy hub optimisation. This paper solves the optimal energy flow of adjacent energy hubs to minimize the energy costs by utilizing the flexibility of energy resources in a smart city with uncertain renewable generation. It innovatively models the power and gas flows between hubs using chance constraints, thus permitting the temporary overloading acceptable on real energy networks. This novelty not only ensures system security but also helps reduce or defer network investment. By restricting the probability of chance constraints over a specific level, the energy hub optimization is formulated as a multi-period stochastic problem with the total generation cost as the objective. Cornish-Fisher Expansion is utilized to incorporate the chance constraints into the optimization, which transforms the stochastic problem into a deterministic problem. The interior-point method is then applied to resolve the developed model. The proposed chance-constrained optimization is demonstrated on a 3-hub system and results extensively illustrate the impact of chance constraints on power and gas flows. This work can benefit energy hub operators by maximizing renewable energy penetration at the lowest cost in a smart city.
Droop-Controlled Rectifiers that Continuously Take Part in Grid Regulation IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : Qing-Chang Zhong; Zijun Lyu
In this paper, a general framework for a rectifier to continuously take part in the regulation of grid voltage and frequency is proposed. It can automatically change the power consumed to support the grid, without affecting the normal operation of the load. Such a rectifier has a built-in storage port, in addition to the normal AC and DC ports. The flexibility required by the AC port to support the grid is provided by the storage port without affecting the DC port. The grid support of the AC port is achieved through the recently-proposed universal droop controller (UDC). A DC-bus voltage controller is cascaded to the UDC to regulate the DC-bus voltage of the storage port within a wide range to provide the flexibility needed while the DC-port voltage is maintained constant. An illustrative example is presented with the recently-proposed theta-converter, which consists of three ports with only four switches. Experimental results are provided to verify the capability of the rectifier to regulate the grid voltage and frequency without affecting the load.
A Multiple-Input Cascaded DC-DC Converter for Very Small Wind Turbines IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : Yamaan E. Majeed; Iftekhar Ahmad; Daryoush Habibi
Concerns over environmental impact and high infrastructure cost heavily influence the uptake of wind turbine technology. Recently researchers have started to look into wind turbines, which are much smaller in size and capacity. Small wind turbines have less environmental impact and low infrastructure cost. These small turbines have limited power generation capacity, requiring multiple turbines to be connected together to produce useful power. In order to capture power from multiple wind turbines, researchers have proposed numerous topologies in the literature. However, these traditional topologies were designed for high-power wind turbines and cannot be used to connect very small wind turbines since a significant amount of the generated power would be lost in driving the complex electronic circuits used in traditional topologies. In this paper, we present a multiple input non-isolated DC-DC converter design that collects the output power from series-connected very small wind turbines. The proposed system was implemented in our smart energy laboratory and experimental results were gathered, showing a significant improvement over existing converters.
Model-Based Current Control Strategy with Virtual Time Constant for Improved Dynamic Response of Three-Phase Grid-Connected VSI IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-10 Sertac Bayhan; Osman Kukrer; Hasan Komurcugil
A model-based current control strategy with a 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 0dB. Unlike the existing methods, the proposed strategy does not require dedicated active damping. Computer simulations and experimental studies show that the proposed control strategy exhibits good performance in achieving fast dynamic response and sinusoidal grid current with low THD under balanced, unbalanced and distorted grid conditions.
PWM Control Algorithm for a Six-phase PMSM: Reducing the Current in the Inverter Capacitor and Current Sensing with Resistors IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-10 Takashi Suzuki; Yoshitaka Hayashi; Hideki Kabune; Norihisa Ito
Motors and inverters are increasingly being used in vehicles. As more vehicle components are being adopted, requirement for safety and installation space are increasing. Growing attention is being paid to the use of six-phase permanent magnet synchronous motors (PMSM) and their parallel control by two inverters, because of their reduced size and enhanced safety. This paper proposes a PWM control algorithm for a six-phase PMSM. In low-voltage vehicle components such as EPS, the current is usually acquired with resistors placed under the low-side switching devices. In the proposed control algorithm, the neutral voltage of the two inverters is shifted to either a lower or higher voltage within a certain range to allow for the signal conditioning time delay after the switching device turns on or off and the time taken for the phase current to rise or settle. The paper proposes a novel PWM control algorithm that ensures the on-time of the low-side switching devices satisfies the restriction on current sensing with resistors and reduces the current in the capacitor at the same time. The work contributes to reducing the current in a practical configuration involving low-voltage vehicle components.
Data-driven Detection and Diagnosis of Incipient Faults in Electrical Drives of High-Speed Trains IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Hongtian Chen; Bin Jiang; Wen Chen; Hui Yi
Incipient faults in electrical drives can corrupt overall performance of high-speed trains; however, they are difficult to be discovered because of their slight fault symptoms. By sufficiently exploiting the distribution information of incipient faults, this paper presents the reason why incipient faults cannot be detected by the existing fault detection and diagnosis (FDD) methods. Under principal component analysis (PCA) framework, we propose a new data-driven FDD method, named probability-relevant PCA (PRPCA), for electrical drives in high-speed trains. The salient strengths of the PRPCA-based FDD method are: 1) It can greatly improve the fault detectability. 2) It is suitable for non-Gaussian electrical drives. 3) Based on the improved fault detectability, it can achieve accurate fault diagnosis via support vector machine (SVM). 4) It can be easily applied to electrical drives even if neither physical models or parameters nor expert knowledge of drive systems is given. 5) It is of highly computational efficiency that can meet requirements on the real-time FDD. A set of experiments on a dSPACE platform based traction system of the CRH2A-type high-speed train are carried out to demonstrate the effectiveness of the proposed method.
A Compact 16-Way High-Power Combiner Implemented via 3-D Metal Printing Technique for Advanced Radio-Frequency Electronics System Applications IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Guan-Long Huang; Chong-Zhi Han; Wei Xu; Tao Yuan; Xiao Zhang
A size-compact and monolithically integrated millimeter-wave 16-way high-power combiner for advanced radio-frequency (RF) electronics applications is developed featuring a wide operational bandwidth and high isolations between the combiner's adjacent ports. The proposed combiner is operating at X band and is composed of 15 3-dB directional coupler units that are properly configured to achieve the overall structural compactness. The combiner is fast prototyped as a single part by employing metallic 3-D printing technique, which successfully overcomes the difficulty in its monolithic implementation by using conventional subtractive manufacturing techniques. The experimental results demonstrate that the 16-way power combiner achieves an approximately 21% operational bandwidth (8.5−10.5 GHz) at X band with port isolations of over 20 dB, an amplitude imbalance of about ±1 dB, a phase deviation of around ±1°, and good return and insertion losses. The excellent RF performance of the combiner makes it a good candidate for applications in multi-port high-power electronics systems where highly efficient power transmission and conversion among different ports are required.
An Intelligent Outlier Detection Method with One Class Support Tucker Machine and Genetic Algorithm towards Big Sensor Data in Internet of Things IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Xiaowu Deng; Peng Jiang; Xiaoning Peng; Chunqiao Mi
Various types of sensor data can be collected by IoT. Each sensor node has spatial attributes and may also be associated with a large number of measurement data that evolve over time; therefore, these high-dimensional sensor data are inherently large scale. Detecting outliers in large-scale IoT sensor data is a challenging task. Most existing anomaly detection methods are based on a vector representation. However, large-scale IoT sensor data have characteristics that make tensor methods more efficient for extracting information. The vector-based methods can destroy original structural information and correlation within large-scale sensor data, resulting in the problem of the “curse of dimensionality,” and some outliers hence cannot be detected. In this paper, we propose a one-class support Tucker machine (OCSTuM) and an OCSTuM based on tensor Tucker factorization and a genetic algorithm called GA-OCSTuM. These methods extend one-class support vector machines to tensor space. OCSTuM and GA-OCSTuM are unsupervised anomaly detection approaches for big sensor data. They retain the structural information of data while improving the accuracy and efficiency of anomaly detection. The experimental evaluations on real datasets demonstrate that our proposed method improves the accuracy and efficiency of anomaly detection while retaining the intrinsic structure of big sensor data.
Model Predictive Current Control of Modular Multilevel Converters with Phase-Shifted Pulse-Width Modulation IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Dehong Zhou; Shunfeng Yang; Yi Tang
Model predictive current control (MPCC) is a promising candidate for modular multilevel converters (MMCs) control due to its advantages of direct modeling and quick dynamic response. The conventional MPCC, which obtains the optimal control input by evaluating a cost function for all the possible switching states, may make the MPCC impractical due to the exponentially increasing computation burden with the increasing number of submodules (SMs). On the other hand, MPCC experiences high load current and circulating current tracking errors since only one switching state is selected and applied during one control period. To address these issues, this paper proposes an MPCC with phase-shifted pulse-width modulation (PS-PWM) for improving the steady-state control performance. The arm voltages are considered as a whole to implement the proposed MPCC. The optimal duty cycle is obtained based on the load and circulating current tracking error minimization and applied using a PS-PWM. As a result, the computation burden is unrelated to the number of SMs by avoiding the exhaustive evaluation process for all the possible switching states. A better steady-state performance is achieved and the tedious tuning process of weighting factor is eliminated. Experimental results are presented to demonstrate the effectiveness of the proposed MPCC.
Electromechanical coupling mechanism and control strategy for in-wheel motor driven electric vehicles 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 IWM-EVs (in-wheel-motor electric vehicles). Unlike existing techniques and methods, the proposed investigation focus on the electromechanical coupling effects between subsystems in IWM-EV which was considered as another negative effects bought by power integration. To this aim, an integrated model which describing 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 are 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 benefit 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 effects on output torque and speed tracking ability.
Development of a Novel Transverse Flux Tubular Linear Machine with Parallel and Complementary PM Magnetic Circuit for Precision Industrial Processing IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Xing Zhao; Shuangxia Niu
Because of its high torque density and efficiency, transverse-flux permanent-magnet linear machine (TF-PMLM) has attracted much attention for high-performance direct-drive applications. Whereas, caused by its inherent large open-circuit flux leakage, the prominent cogging force makes it difficult to obtain a high position and speed control accuracy, which restricts its potential for precision industrial processing applications. To overcome this problem, a novel transverse-flux linear machine is proposed. The key is by creatively combining a consequent-pole mover design and stator-segment-interlacing configuration, in such a way, a parallel and complementary transverse magnetic circuit is constructed for the moving PMs, which can effectively minimize the open-circuit leakage flux and cogging effect. In this paper, the machine structure, operation principle and theoretical modeling are introduced, with its electromagnetic performance evaluated by using finite element method. A prototype is also built for the experimental verification and relevant test results agree well with the finite element predications.
An Integrated Heater-Equalizer for Lithium-Ion Batteries of Electric Vehicles IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Yunlong Shang; Chong Zhu; Yuhong Fu; Chunting Chris Mi
An automotive onboard heater-equalizer is proposed to heat low-temperature batteries and balance cell voltages without the requirement of external power supplies. The proposed integrated topology only needs one MOSFET for one cell, resulting in a compact size and low cost, which can be easily applied to electric vehicles (EVs). Particularly, all MOSFETs are driven by one high-frequency PWM signal, and the batteries can be heated internally by the ohmic and electrochemical losses and warmed externally by the switching and conduction losses of MOSFETs, leading to a high heating speed and efficiency. Further, a thermoelectric model for the internal and external combined heating is developed to provide a guidance for the optimized design of the proposed heater. In addition, the proposed topology can also realize passive balancing of series-connected battery strings at a higher switching frequency and a smaller duty cycle. Experimental results show that the proposed heater, by generating a periodic ramped discharge current with an RMS value of 1.8 C at a switching frequency of 150 kHz, can heat the lithium-ion batteries from −20 °C to 0 °C within 1.9 mins, consuming about 5% of the cell energy.
Design of a Novel Parallel-Hybrid-Excited Dual-PM Machine Based on Armature Harmonics Diversity for Electric Vehicle Propulsion IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Xing Zhao; Shuangxia Niu; Weinong Fu
A novel parallel-hybrid dual-PM machine topology with both enhanced torque density and improved flux weakening capability, is proposed for electric vehicle propulsion in this paper. The key is to artificially construct the harmonics diversity with a single-layer concentrated armature winding in the stator and thus simultaneously couple the armature field with the excitation field produced by slot PM, rotor PM and stator DC source, respectively. Enhanced torque density is obtained in this new topology due to the symmetrical flux modulation effect between dual PM sources. Moreover, benefiting from a parallel excitation characteristic of hybrid magnetic circuit, the demagnetization risk is significantly mitigated for slot PM source and thus an extended flux weakening range is obtained. In this paper, the proposed new topology and its design mechanism are investigated, along with its electromagnetic performance evaluated based on finite element analysis. Further, some leading design parameters are analyzed and determined to provide a design guideline for the proposed new topology. Finally, a prototype is built and fully tested. Relevant experimental results agree well with the finite element predication.
PWM A-CHB Converter Based on Trinary Multilevel Converter: Topology, Switching Algorithm, and Stability Analysis IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-09 Saleh Ziaeinejad; Ali Mehrizi-Sani
A trinary multilevel converter (TMC) uses a few heterogeneous H-bridge submodules to synthesize an output voltage with multiple levels. Two major limitations of this converter are that (i) it needs multiple DC sources and (ii) it can not operate under PWM. This paper addresses these limitations by adding a low-voltage H-bridge submodule to this converter and proposing a new switching algorithm. The resulting PWM-based asymmetric cascaded H-bridge (A-CHB) 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 standalone and grid-connected modes of operation.
Exact Nonlinear Micro-Modeling for Fine-Grained Parallel EMT Simulation of MTDC Grid Interaction with Wind Farm IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-06 Ning Lin; Venkata Dinavahi
Detailed high-order models of the insulated-gate bipolar transistor (IGBT) and the diode are rarely included in power converters for large-scale system-level electromagnetic transient (EMT) simulation on the CPU, due to the nonlinear characteristics albeit they are more accurate. The massively parallel architecture of the graphics processing unit (GPU) enables a lower computational burden by avoiding the computation of complex devices repetitively in a sequential manner and thus is utilized in this work to simulate the wind farm-integrated multi-terminal DC (MTDC) grid based on the modular multilevel converter (MMC). Fine-grained circuit partitioning is proposed so that the nonlinear switching elements are physically separated with the smallest circuit unit. By implementing these subsystems with the same attributes as a GPU program and computing it in a massively parallel manner, it is demonstrated that the GPU is able to achieve a significant speedup over multi-core CPUs and its computation time incremental is much smaller when the MMC level scales up. The improved insight and accuracy of the proposed modeling methodology and the designed GPU program are validated at the system- and device-level by off-line commercial simulation tools.
Hardware-in-the-Loop Methods for Real-Time Frequency-Response Measurements of on-Board Power Distribution Systems IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-06 Tomi Roinila; Tuomas Messo; Roni Luhtala; Rick Scharrenberg; Erik de Jong; Alejandra Fabian; Yin Sun
The operation of more electric aircraft is dependent on the embedded power grid. Therefore, the on-board power-distribution system must be reliable, having a high level of survivability, and promptly respond to any change in aircraft's operation. Recent studies have presented a number of frequency-response-based tools with which to analyze both single- and multi-converter systems. The methods can be efficiently applied for on-board system analysis, stability assessment and adaptive control design. Most often, wideband measurement techniques have been applied to obtain the frequency response from a specific converter or a subsystem required for the analysis. In the methods, a broadband excitation such as a pseudo-random binary sequence (PRBS) is used as an external injection, and Fourier techniques are applied to extract the spectral information. This paper presents implementation techniques of the wideband methods using power-hardware-in-the-loop measurements based on OPAL-RT real-time simulator. The presented methods make it possible to modify the system characteristics, such as impedance behavior, in real time, thereby providing means for various stability and control design tools for on-board power distribution systems. Experimental measurements are shown from a high-power energy distribution system recently developed at DNV GL, Arnhem, Netherlands.
Discrete-Time Complex Bandpass Filters for Three-Phase Converter Systems IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-03 Emerson Guest; Nenad Mijatovic
A first-order complex bandpass filter (CBF) derived in the discrete frequency domain is proposed as a building block for the complex signal processing unit in three-phase converter systems. The first-order discrete CBF can be directly implemented in a digital system, is stable at all center frequencies and has a low computational burden. The first-order CBF is extended to a pth-order discrete CBF. A normalized frequency-locked loop (FLL) is then developed that allows the frequency adaption to satisfy a desired settling time regardless of the input signal magnitude or discrete CBF form. The pth-order discrete CBF-FLL was tested on an FPGA in the form of two industrial applications: voltage synchronization under grid fault and extraction of an unknown frequency component. The second-order discrete CBF-FLL offered significantly improved stopband attenuation and frequency estimation relative to the first-order discrete CBF-FLL, for a small increase in computational burden.
High Step-up Transformer-less Inverter for AC Module Applications with Active Power Decoupling IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-03 Jinia Roy; Yinglai Xia; Rajapandian Ayyanar
This paper explores a power conversion system for single phase transfomer-less AC module application. A nonisolated high gain dc-dc stage is coupled with a doubly-grounded dynamic dc-link inverter to implement the microinverter topology. The front-end boost stage steps up the single module voltage to a higher dc voltage, typically to 200V or 400V as required for the following inverter stage. It is a hybrid of an interleaved boost and switched capacitor concept capable of achieving high gain while simultaneously maintaining reduced voltage and current stress and thus lower switching and conduction loss for most of the switches. By directly connecting the grid-neutral to the PV negative, the doubly-grounded voltage-swing inverter has the advantage of zero capacitive-coupled common-mode ground currents, critical for transformer-less PV inverters. The two dc-links of the inverter stage share the double line frequency power decoupling with a combination of higher value of mean voltage and relatively large 120Hz ripple component - the dynamic dc-link approach. Through an optimization algorithm, the decoupling capacitance is minimized enabling an all-film capacitor implementation while satisfying the converter's operating constraints over a wide range of power-factor. The simulation as well as experimental results from a GaN based hardware-prototype validate the converter's performance.
Alternative Approach to Analysis and Design of Series Resonant Converter at Steady State IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-03 Mohammad Daryaei; Mohammad Ebrahimi; S. Ali Khajehoddin
A new steady-state analysis is proposed for Series Resonant Converter (SRC) that provides closed-form expressions for converter waveforms. Using the proposed analysis, explicit equations are obtained to design the converter components. It is shown that SRC can be modeled through a nonlinear differential equation with discontinuous inputs. A Laplace Based Theorem (LBT) is provided to obtain the steady-state analytic solution of the resonant converter differential equations. Using the LBT, a flowchart is proposed to analyze the converter where the nonlinearity of differential equation is removed by defining intermediate variables. The variable duty ratio SRC is analyzed using the proposed flowchart. Accurate, closed-form and explicit equations for converter waveforms, voltage gain, current phase lag, ZVS and DCM boundaries are derived. The proposed analysis is compared with conventional methods and its accuracy is validated through simulations and experimental results. Moreover, using the proposed method, a novel procedure is provided for the optimal design of the converter and is compared with conventional design approaches.
Pseudo-full-bridge inverter with soft-switching capability for quarter-phase ultrasonic motor 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 unique in terms of the shared arms and the specially-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.
A Generalized Method to Generate Carrier-Based 3L PWM Techniques using Two Parallel Interleaved 2L VSIs 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 pulse-width modulation (PWM) techniques using two parallel interleaved 2L VSIs. The proposed method modifies the given three-phase reference signals of 3L inverter for implementation of the PWM technique using two parallel interleaved 2L inverters. The influence of non-idealities on the equivalent 3L PWM switching sequences is also discussed. To overcome the effect of non-idealities, 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.
Generic Closed Loop Controller for Power Regulation in Dual Active Bridge DC/DC Converter with Current Stress Minimization IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Osama Mohamed Hebala; Ahmed Aboushady; Khaled Hani Ahmed; Ibrahim Abdallah 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) tool 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 enabled 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 precision of the proposed closed loop controller under various operating conditions. An experimental prototype also substantiates the results achieved.
Power Frequency Harmonic Reduction and its Re-Distribution for Improved Filter Design in Current-fed Switched Inverter IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Anil Gambhir; Santanu K. Mishra; Avinash Joshi
Due to pulsating power at the inverter output terminals, the passive storage elements of boost stage of the Current-fed Switched Inverter (CFSI) contains power frequency harmonic component (100 Hz) apart from DC and switching frequency components. In prior designs, the second harmonic component is suppressed by increasing the size of input filter inductor and capacitor or by using additional circuits. This paper presents the complete characterization of a control based approach to suppress power frequency harmonic component in input inductor current of a CFSI. It also presents a comprehensive characterization of the harmonic power redistribution. Using the proposed approach, it is demonstrated that the inductor value of a CFSI is reduced by 61 % for the same peak-to-peak ripple. This leads to improvement in the conversion ratio, efficiency, and power density of the overall converter. A SiC Mosfet based CFSI with 75 kHz switching frequency is used to verify the proposed design philosophy.
Modelling and Analysis of Inductive Power Transfer System with Passive Matrix Power Repeater IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Rong Hua; Patrick Aiguo Hu
This paper presents a detailed modelling and analysis of an Inductive Power Transfer (IPT) system with a passive matrix power repeater. A high order mathematical model is established to characterise the output power by taking all the mutual inductances between the primary, secondary, and the unit cells of matrix power repeaters into considerations. The model is used to analyse the relationship between the output power and the operating frequency of an IPT system with a 3×3 matrix power repeater. The study shows the optimal operating frequencies corresponding to maximum and minimum power transfer exist owing to the interactions among the magnetic fields generated by the primary current and induced currents of the unit cells of the matrix power repeater. The theoretical optimal frequencies for obtaining the maximum and minimum output power are determined by numerical analysis based on the proposed model, and they are verified by circuit simulation and experimental study within an error of 2%. The results are useful for power flow controller design with enhanced and reduced power regulation range.
Modular Multilevel Converter Based Variable Speed Drive with Reduced Capacitor Ripple Voltage IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Shambhu Sau; B. G. Fernandes
In recent years, modular multilevel converter (MMC) is being considered for medium voltage variable speed drives (VSD) due to its modularity and higher reliability. However, the major drawback of the MMC based VSD is the higher capacitor ripple voltage at lower operating speeds. In literature, this ripple voltage is reduced by injecting a high-frequency circulating current into each arm. This additional circulating current increases the overall current rating of the devices, inductors, and capacitors. Alternatively, the capacitor ripple voltage can be reduced at the lower output frequency by reducing the dc-bus voltage. This paper proposes a new configuration using a multipulse diode-bridge rectifier to reduce the dc-bus voltage when the drive is operated at lower speeds. Therefore, the capacitor ripple voltage decreases without injecting any circulating current. In addition, a new technique is proposed to maintain the peak-to-peak value of the submodule capacitor ripple voltage constant at near zero speed. The proposed converter with 24-pulse rectifier configuration is simulated in MATLAB/Simulink, and the experimental validation is carried out on a prototype with 12-pulse rectifier.
Smartwatch Strap Wireless Power Transfer System with Flexible PCB Coil and Shielding Material IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Seungtaek Jeong; Dong-Hyun Kim; Jinwook Song; Hongseok Kim; Seongsoo Lee; Chiuk Song; Joungho Kim; Jaehak Lee Lee; Joonyub Song
In this paper, we designed and demonstrated a smartwatch strap wireless charging system for the first time. First, we designed a flexible PCB coil, shielding material, and receiver (Rx) circuit in a watchstrap. In the design process, we proposed a model for the flexible PCB coil with a bending radius of 40 mm and shielding materials. We used a flexible PCB coil that has 215 μm thickness with dimensions of 54.5 mm x 16 mm. In addition, ferrite core and sheet are applied on the transmitter (Tx) and Rx coils. We verified the proposed model through a 3D EM simulation and measurement in the frequency and time domains. The proposed flexible PCB coil inductance modeling results showed 7.5% and 3.4% errors when compared to the 3D EM simulation and measurement results, respectively. Furthermore, we demonstrated the smartwatch strap wireless charging system using an LG Watch Urbane. A resonance frequency of 100 kHz with the series-series tuning topology is used in accordance with the Qi specifications. Finally, we achieved 30% dc-dc power transfer efficiency and exposed magnetic field of 270 mG 1 cm away from the system through measurements.
Modeling and Design of Contactless Sliprings for Rotary Applications IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Guangming He; Qianhong Chen; Xiaoyong Ren; Siu-chung Wong; Zhiliang Zhang
Contactless sliprings (CS) based on inductive power transfer (IPT) offer a safe and reliable power transfer solution for rotary applications. An accurate reluctance model for CS is presented in this paper along with the associated parameters identification, considering the partially linking effect of the magnetic flux. Aiming to obtain higher coupling coefficient and lighter weight, a design optimization for CS is also proposed by defining a new design parameter "$\zeta$". Both simulations and experimental measurements are presented to verify the effectiveness of the proposed modeling method. The maximum errors (between the identified results and the measured results) of the mutual inductance, the leakage inductance, and the coupling coefficient are 8.72%, 7.12%, and 5.98%, respectively, when the gap is less than the core window width. Comparative studies among different modeling methods are carried out, which testify that the proposed method has the highest accuracy. Finally, a 1.5kW IPT system employing the designed CS is fabricated for verification.
Charging Area Determining and Power Enhancement Method for Multi-Excitation Unit Configuration of Wirelessly Dynamic Charging EV System IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Xin Dai; Jincheng Jiang; Jianqing Wu
EV dynamical wireless changing is an emerging application area of wireless power transfer technologies. Compared with classical static charging mode, there are two key challenges in dynamical charging process. One is to determine charging area and corresponding excitation unit. The other is to provide large energy in a short time interval. Based on multi-excitation unit configuration for EV dynamical charging, this paper proposes a charging area determining method. The dynamical mutual inductance can be calculated based on DC current input and load detection. A charging area can be figure out based on output power requirement. And a switching mode method is given to control charging process for multi-excitation unit configuration. On the basis, a power and efficiency enhancement method is proposed by utilizing multi-excitation unit in the charging area. This method is beneficial for improve system power capacity without voltage and current stress increasing. Finally, experimental results show this method can realize accurate charging area determining and control. And the output power of dual excitation unit configuration can increase almost 4 times than tradition single excitation unit configuration.
Finite-time Convergent Control of Electro-hydraulic Velocity Servo System under Uncertain Parameter and External Load 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 electro-hydraulic 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 study, a finite-time convergent controller (FTCC) is tried to use in electro-hydraulic system to address this problem. Different from asymptotic convergent controller, this FTCC cannot 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.
Stepwise Magnetization Control Strategy for DC-Magnetized Memory Machine IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Hui Yang; Shukang Lyu; Heyun Lin; Z.Q. Zhu; Fei Peng; Erxing Zhuang; Shuhua Fang; Yunkai Huang
Memory machine (MM) equipped with hybrid permanent magnets (PMs), i.e., NdFeB and low coercive force (LCF) PMs, exhibits acceptable torque capability at low speeds and high efficiency at high speeds. Previous literatures have addressed that the constant power speed range (CPSR) of MMs can be further extended by online PM flux control, and the requirement of flux-weakening (FW) inverter current can be reduced as well. Nevertheless, how to coordinate the d-axis vector FW and PM magnetization control over a whole operating range in a reasonable manner remains unreported. Therefore, this paper proposes and implements a stepwise magnetization control strategy on a DC-magnetized memory machine based on the operating characteristics under various PM magnetization states and speed ranges. The configuration, principle and mathematical model of the investigated machine are introduced first. Then, the proposed control strategy is established by dividing the operating envelop into several FW regions, and an appropriate FW control scheme is utilized at each stage. It demonstrates that the CPSR can be effectively extended by simply applying the demagnetizing current pulses in several steps. This simplifies the control efforts considerably without resorting to continuous PM flux control and frequent actions of the switching devices. The effectiveness of the proposed control strategy is verified by experimental results.
Multi-Objective Coordinated Scheduling of Energy and Flight for Hybrid Electric Unmanned Aircrafts IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Sidun Fang; Yan Xu
A hybrid electric unmanned aircrafts (HEUA) uses the aerial thermal engine and energy storage system (ESS)-driven electric motor to meet the load demand, thus can be viewed as a “mobile multi-energy microgrid”. Conventionally, for a given flight mission, only the energy of a HEUA is optimized while the flight speed is fixed, thus the overall energy efficiency may be limited. This paper aims to coordinately schedule the energy consumption and the flight speed of a HEUA towards optimal economic and environmental objectives. First, a coordinated optimization model is proposed to coordinately schedule the energy consumption (including the power output of the thermal engine and the ESS) and flight speed (i.e., the true air speed) of a HEUA for simultaneously minimizing the fuel consumption (FC) and polluted gas emission (PGE). Second, a decomposition-based solution method is developed to convert the original non-linear multi-objective optimization model into a bi-level programming model which can be solved iteratively. Simulation results demonstrate that, compared with the conventional single energy scheduling, the proposed coordinated scheduling method can achieve much better performance in terms of FC and PGE.
MRAS based Speed Estimation of Induction Motor Drive Utilizing Machine's d- and q- Circuit Impedances IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Sukanta Das; Rakesh Kumar; Abhisek Pal
The present work proposes a new model reference adaptive system (MRAS) for sensorless speed estimation of field oriented induction motor (IM) drive utilizing d- and q- circuit effective impedances. The functional quantity of the MRAS, in this context, is the difference between the stator d- and q- circuit effective working impedances. This unique structure does not require any flux computation while estimating speed. Moreover, the formulation is free from any resistance terms. The proposed estimator performs satisfactorily at all the operating points and exhibits stability in all the four quadrants of drive's operation. The relevant stability and sensitivity studies, in this regard, are done in MATLAB/Simulink. Furthermore, the controller performance is validated experimentally by dSPACE-1103 based IM drive setup.
Fast Estimation of Phase and Frequency for Single Phase Grid Signal IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Hafiz Ahmed; Sid-Ali Amamra; I. Salgado
Accurate and fast estimation of single phase grid voltage phase and frequency has the potential to improve the performances of various control and monitoring techniques used in electric power system. This letter applies an adaptive sliding mode observer for frequency and phase estimation. The observer is simple, easy to tune and suitable for real-time implementation. The proposed adaptive observer can be considered as an alternative to phase-locked loop (PLL) with better performance. dSPACE based experimental results are given to show the effectiveness and performance improvement of the proposed approach with respect to two other advanced PLL techniques namely pseudo linear - enhanced PLL (PL-EPLL) and Second order generalized integrator- frequency locked loop (SOGI-FLL).
Design and Development of a Novel High Voltage Gain, High Efficiency Bi-directional DC-DC Converter for Storage Interface IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Shreelakshmi M P; Moumita Das; Vivek Agarwal
A novel bi-directional dc-dc converter having high voltage gain capability with high efficiency is proposed 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 500W 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.
Development and Analysis of Novel Flux Switching Transverse Flux Permanent Magnet Linear Machine IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Mei Zhao; Yao Wei; Hongyong Yang; Mingming Xu; Fujun Han; Guanlong Deng; Dianli Hou; Ping Zhang
The flux-switching transverse flux permanent magnet linear machine (FSTFPMLM) is proposed in this paper combining the advantages of transverse flux linear machine and flux-switching linear machine. Firstly, the structure and operating principle of FSTFPMLM is presented. Secondly, the magnetic field of a simplified FSTFPMLM is numerically computed by three-dimensional (3-D) finite element method (FEM). Thirdly, the thrust characteristics of the machine, including thrust force, cogging force and force ripple are numerically analyzed. The influence of structure parameters on the thrust characteristics has been analyzed by 3-D FEM. The law of thrust, cogging force and force ripple as the pole pitch ratio between primary and secondary and the ratio between tooth width and pole pitch of secondary variable provides the guidance to design FSTFPMLM, which aims to achieve the larger thrust, smaller cogging and force ripple using less permanent magnet materials. The thrust force capabilities of FSTFPMLM are compared with other topologies of linear machines. Finally, the prototype and experimental setup have been developed, and the calculated results and the measured results are in good agreement.
Multiobjective Two-Dimensional CCA-Based Monitoring for Successive Batch Processes with Industrial Injection Molding Application IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Qingchao Jiang; Furong Gao; Xuefeng Yan; Hui Yi
Successive batch processes generally involve within-batch and batch-to-batch correlations, and monitoring of such batch processes is imperative. This study proposes a multiobjective two-dimensional canonical correlation analysis (M2D-CCA)-based fault detection scheme to achieve efficient monitoring of successive batch processes. First, three-way historical batch process data are unfolded into two-way time-slice data. Second, for each time-slice measurement, CCA is performed between the current measurement and previous measurements from both time and batch directions, which takes the within-batch and batch-to-batch correlations into account. To determine the involved measurements and eliminate the influence of unrelated variables, multiobjective evolutionary optimization is performed, which tries to maximize the preserved canonical correlation coefficients and minimize the number of involved variables. Finally, based on the established M2D-CCA model, an optimal fault detection residual is generated for each time-slice measurement. The M2D-CCA fault detection scheme performs fault detection using the current measurement and the information provided by its previous samples and batches, and therefore exhibits a superior monitoring performance. The M2D-CCA fault detection approach is tested on a numerical example and an industrial injection molding process. Monitoring results verify the feasibility and superiority of the proposed monitoring scheme.
A 300 000-r/min Magnetically Levitated Reaction Wheel Demonstrator IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Arda Tuysuz; Timon Achtnich; Christof Zwyssig; Johann Kolar
Magnetic bearings can be used in reaction wheel systems to avoid several drawbacks of ball bearings, such as limited life time due to mechanical friction and lubricant monitoring/sealing requirements. Therefore, this letter discusses an electrical machine topology with integrated reaction wheel and magnetic bearings. The slotless/ironless structure, together with a new electromagnetic arrangement resulting in a shorter rotor than in earlier works, enables efficient operation at very high speeds, which in turn enables the miniaturization of the system. Measurements taken on a demonstrator prototype at 300 000 r/min show a significant increase of the feasible operational speed range compared to the state-of-the-art reaction wheels for small satellites, which typically run below 10 000 r/min.
Angle tracking adaptive backstepping control for a mechanism of pneumatic muscle actuators via an AESO IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Ling Zhao; Haiyan Cheng; Yuanqing Xia; Bo Liu
This paper presents an adaptive backstepping controller for a mechanism of pneumatic muscle actuators via an adaptive extended state observer. A dynamic model of the mechanism is established with two unknown parameters estimated by using adaptive laws. An adaptive extended state observer is established to estimate total disturbances and states of the mechanism. Moreover, adaptive extended state observer gains are obtained by adaptive laws and parallel D-eigenvalues whose time-varying multiplier n-order derivatives are derived by tracking differentiators. Finally, a nonlinear adaptive backstepping controller is designed and the effectiveness of the proposed method is expressed by experimental results.
Electromagnetic and Thrust Characteristics of Double-sided Permanent Magnet Linear Synchronous Motor Adopting Staggering Primaries Structure IEEE Trans. Ind. Electron. (IF 7.05) Pub Date : 2018-08-01 Xu zhen Huang; Jing Li; Chengming Zhang; Zhenyu Qian; Liyi Li; David Gerada
Traditionally, straggering the primaries of the double-sided permanent magnet linear synchronous motor (DS-PMLSM) is beneficial in helping to reduce the detent force caused by the longitudinal end effect, but leading to a reduction of the average thrust. To overcome this disadvantage, this paper provides a novel DS-PMLSM, which adopts the structure of staggering two primaries and rearranging windings. Firstly, the characteristics of the voltage and detent force are analyzed theoretically and verified by finite element (FEM) simulations. The inductance, thrust and normal forces are then compared with the traditional DS-PMLSM. Furthermore, the geometrical parameters are optimized to improve the thrust. Finally, one DS-PMLSM prototype is tested. The detent force and back EMF tested results verify the effectiveness of the topology proposed in this research.
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