Search

Low-cost electric vehicles (EVs) prefer induction motor (IM) based drive systems which are mostly operated with 2-level inverters (2LIs) because they require fewer component counts and minimum control complexity. While an IM operated with 2LI has a higher total harmonic distortion (THD) and lower efficiency. An indirect current vector control (ICVC) scheme is an effective and simplest control scheme used for IM of EVs. This ICVC scheme required one speed sensor and three current sensors which increased its cost and control complexity. Therefore, in this paper, a cascaded H-bridge 3-level inverter (CHB-3LI) fed IM drive (IMD) is presented. A modified ICVC scheme having only one speed sensor is presented and used to control the CHB-3LI fed IMD. The steady-state and transient performances of CHB-3LI fed IMD with the modified ICVC scheme are analyzed through simulation in MATLAB Simulink and validated through experiments on a developed laboratory setup.

Vector controlled induction motors (IMs) are used in electric vehicles (EVs) for effective speed control. The use of three-level inverter (3LI) offers the advantage of reduced switch stress along with lower total harmonic distortion in voltage (THDv) over two-level inverters. An indirect current vector control (ICVC) scheme has one proportional-integral (PI) controller for speed control of EV. The selection of controller coefficients affects the performance of complete drive. Therefore, this paper uses particle swarm optimisation technique for optimum selection of controller coefficients used for the control of CHB3LI fed IM drive. This drive is tested under CBD, COMMUTER, and EU driving cycles on three torque loadings through simulation in MATLAB Simulink and validated experimentally on a reduced scale laboratory setup. The obtained results are presented to demonstrate desired performance under all the driving cycles for optimised controller coefficients along with improved THDv and reduced losses in the IM.

Electric Vehicle is the future of sustainable road transport. One of the important issues with electric vehicles is their inverter failure. This paper presents a fault-tolerant technique with phase fault detection and fault removal for a three-phase cascaded H-bridge three-level inverter. The phase fault-detection and fault-removal techniques are based on the switch voltage, switch current and switching signal detection. The cascaded H-bridge three-level inverter is made fault-tolerant by using an additional H-bridge and three bidirectional IGBT switches. The logic of phase fault detection and fault removal is investigated in the MATLAB-Simulink environment and validated in OPAL RT-LAB.

In this paper, a nine-level inverter topology is proposed with the least number of switches and other components for fault tolerant (FT) operation. The proposed fault tolerant topology requires only one additional switch to execute the fault tolerant operation. The proposed topology also results in reduced total harmonic distortion (THD) as compared with other reported fault tolerant topologies for a 9-level output. A detailed analysis of the topology is presented and the fault tolerant operation is demonstrated under any single, double, triple, and quadruple switch faults using MATLAB/ Simulation and OPALRT hardware in loop (HIL) real time simulator. The proposed concept is validated for single and multiple switch faults and R-L load variation on a low scale laboratory hardware set-up.

This work presents a cross-connected sources asymmetric T-type multilevel inverter (CCSATT-MLI) for single-phase operation with fault tolerant (FT) capabilities. The presented topology uses only one extra power semiconductor switch in the CCSATT 13-level (13L) inverter for fully FT operation. The paper uses two control schemes namely phase opposition disposition sinusoidal pulse width modulation (POD-SPWM) and nearest level control (NLC) for achieving the desired results under single switch open circuit (SSOC) fault. The obtained simulation results of proposed topology using MATLAB/Simulink are presented to show FT operation of the MLI under any SSOC fault. The simulation validations are validated under each switch fault using OpalRT hardware in loop (HIL) platform. The presented topology is also compared with recently reported MLI topologies for reduced number of count claim and effective FT operation in symmetric as well as asymmetric configurations.

Linear Motors are potential candidates for replacing traditional rotary motors in high-speed transit systems. Linear Switched Reluctance Motor (LSRM) is the widely researched motor for such applications. This paper presents a design for linear switched reluctance motor (LSRM) with an improved propulsion force profile. The proposed motor consists of moving translator for direct drive transmission, without the use of mechanical gears. The stator contains a split-teethed stator structure. The proposed motor has more translator teeth than stator teeth. This paper includes a new design methodology for the proposed combination of stator and translator. The motor is designed and analyzed using 3-D finite-element method (FEM). The proposed motor has been optimized using a parameter-based cumulative deterministic optimization algorithm (PBCDOA) for further improving the force profile. The FEM results demonstrate the effectiveness of the design procedure and better force performance of the proposed topology.

Maladaptive consumption represents potentially uncontrollable and self- and others-harming consumer choices to fulfill a desire for rewarding substances and behaviors. More recently, maladaptive consumption has emerged as a pivotal interest within consumer research, and a deliberation of current developments regarding consumers’ misuse of substances and their repetitive engagement in certain behaviors highlights its acute importance. After summarizing both long-standing and emerging types of maladaptive consumption, we review mounting evidence and provide a working definition and an integrative theoretical framework for understanding antecedents, types, explanations, and consequences of maladaptive consumption. Finally, we close with a limited identification of propositions and research themes that suggest avenues for future research.

Perfectionism has been conceptualized as a multidimensional construct, and two of its key dimensions entail striving for high performance standards and focusing on the discrepancy between one’s standards and actual performance. Our investigation examines the role of these two dimensions in maladaptive consumption. Results across six studies investigating both trait and state perfectionism across various maladaptive domains support our account that discrepancy-based perfectionism is associated with higher levels of maladaptive consumption than standards-based perfectionism. Additionally, results indicate that feelings of shame and guilt explain these differential effects, with discrepancy perfectionism associated with higher levels of shame and standards perfectionism associated with higher levels of guilt.

Implicit theories are the beliefs that individuals hold regarding the nature of human and nonhuman attributes, as well as more global phenomena. Over the past three decades, social and consumer psychologists have garnered a rich set of findings from investigating the processing and judgmental impact of implicit theories on various facets of people's day‐to‐day lives. This review begins with a brief summary of the history of implicit theory research before explicating its current state in consumer psychology. The review categorizes the current, and rather fragmented, landscape of the consumer psychology of implicit theories into three broad areas: brands, persuasion, and consumption behaviors. We conclude our review by contributing to an expanding dialogue regarding the future of consumer research pertaining to implicit theories.

Consistently rising environmental concerns and depleting petroleum resources have accentuated the need of sustainable, energy efficient and clean means of transport. This has provided the impetus to the research and development of clean alternatives for existing public transportation systems. Development of linear motor-propelled, contact-less maglev systems is considered a promising alternative to conventional on-wheel rail transport technology. Maglev technology primarily focuses on improving the performance, speed, fuel economy, driving range and operating cost of the transit system. These parameters vary with the design and efficiency of the electrical system used in maglev-based transportation systems. To present this study, firstly, a detailed survey of the important constituents of a maglev electrical system has been carried out with techno-economic perspectives. Contemporary maglev technologies have then explored along with their respective advantages and limitations. Electrical systems form the heart of maglev systems and, therefore, this paper presents the components of a standard electrical system together with the comparative analysis in terms of present trends, on-going technological advancements and future challenges.

ABSTRACTRecently, multilevel inverter (MLI) is gaining immense popularity due to reduced total harmonic distortion, lower electromagnetic interference, and high quality output waveform in high/medium voltage applications. The reduced part count (RPC)-MLI has attracted the researchers by providing higher number of output voltage level with reduced part count as compared to the classical topologies (cascaded H-bridge, neutral point clamped, and flying capacitor). But the discussion over their suitability for particular application is not yet explored completely. In this paper, some of the recently proposed RPC-MLI topologies are reviewed and analysed. RPC-MLI topologies are compared on the basis of number of switches, driver circuits, diodes, standing/blocking voltage across the switches, and switching losses for grid interfacing application. These topologies are simulated here under the same load and input source condition using real time simulator.

ABSTRACTIn this paper, an improvisation of cross-connected sources based multilevel inverter (CCS-MLI) topology is presented in terms of maximization of levels. The proposed modified CCS-MLI will boost the output levels with the addition of one bidirectional switch in the existing CCS-MLI. The proposed modified topology lowers the switches number, diodes, gate drivers, dc power supplies, size, installation area and the cost of the system in comparison with conventional topologies and existing CCS-MLI. Working of the proposed topology is presented through a mathematical modelling and switching table. Finally, to confirm the effective performance of the proposed topology, simulation results by MATLAB/simulation and experimental results are given.

ABSTRACTAdaptive control involves modifying the control law used by the controller to cope with the fact that the parameters of the system being controlled change drastically owing to change in environmental conditions or in the system itself. The adaptive control process continuously and automatically measures the dynamic behaviour of plant, compares it with the desired output and uses the difference to vary adjustable system parameters or to generate an actuating signal in such a way that optimal performance can be maintained regardless of system changes. This paper deals with the application of different adaptive schemes in the control system and provides a detailed comparison between the schemes on the basis of their approach to deal with the control problem. A comparative analysis is presented to show the effectiveness of adaptive control techniques during transients in the area of power quality improvement with a shunt active power filter. A classified list of more than 90 publications on this topic is also given for quick reference.

Three-level diode clamped inverter is a proven technology nowadays in medium and high power applications. Despite of its several advantages such as harmonic reduction and achieving high voltage and high power capabilities without series and parallel connections of switching devices, neutral point potential (NPP) variation is the inherent problem with this topology. This paper presents a simple NPP regulator based on addition of offset voltage to the reference sinusoidal voltages. This not only regulates the NPP, but also reduces the output voltage and current harmonics of the inverter. Simultaneously, second harmonic get reduced which may otherwise produce torque pulsations, harmonic currents and power losses. Simulation and experimental results have been presented to validate the concept.

The increasing energy demands, insufficient availability of power generation and increasing global environmental problems, need alternate/green power sources. Among the different green power technologies such as wind power, photovoltaic, gas turbine and fuel cell, the fuel cell-based distributed generation is considered as one of the most promising solutions for stand-alone/grid applications due to its cleanliness, modularity and higher potential capability. The selection of a power conditioning unit plays an important role to maintain the stability of the system and to improve the performance of fuel cell system. While using a single-stage DC/AC inverter with step up transformer for stand-alone/gird applications, the major issue is high current flow through the inverter and primary side of the transformer. This paper presents a two-stage power conditioning unit, a DC/DC boost converter combined with a DC/AC inverter for fuel cell system to reduce the current level at the DC/AC inverter.

The TCSC is a form of FACTS compensator that improves power transfer capability by regulating transmission line reactance. Proper tuning of TCSC results in the variation of inductive/capacitive reactance along with resonance region. A difficulty is observed on tuning the TCSC device; large change in TCSC reactance at critical region (nearby resonance region) prohibits possible fine control of power transfer over the transmission line. This paper therefore investigates the difficulties in tuning of single TCSC in critical region and alternatively proposes split TCSC operation which offers micro tuning of the line reactance. The micro tuning allows for wider degree of compensation over single TCSC operation. The study is carried out on a MATLAB platform and split TCSC results are compared with single TCSC. The simulated reactance characteristic and power angle curve over varied range of firing angles establishes wider degree of possible compensation; a striking benefit of Split TCSC operation.

AbstractDistribution Static Compensator is an important device in correcting power factor, maintaining constant distribution voltage, and mitigating harmonics in a distribution network. This paper focuses on the comparative study of the control techniques for voltage source converter based Distribution Static Compensator, broadly classified as voltage controlled and current controlled. Under the former, phase shift control is compared with the latter, considering indirect decoupled current control and regulation of AC bus and Dc link voltage with hysteresis current control. The first two schemes have been successfully implemented for Static Compensator control at the transmission level for reactive power compensation and voltage support, and are recently being incorporated to control a Distribution Static Compensator employed at the distribution end. The following indices are considered for comparison - measurement and signal conditioning requirement, performance with varying linear/nonlinear load, total harmonic distortion, DC link voltage variation and switching frequency. The paper briefly describes the salient features of each strategy, with their merits and demerits. A dynamic simulation model of the Distribution Static Compensator has been developed for various control strategies, in Matlab/SimPower System environment.

AbstractUse of conventional two-level pulse width modulation (PWM) inverters provide less distorted current and voltage but at the cost of higher switching losses due to high switching frequencies. Multilevel inverters are emerging as a viable alternative for high power, medium voltage applications. This paper compares total harmonic distortion and switching losses in conventional two-level inverters with multilevel inverters (three-level and five-level) at different switching frequencies. An optimized switching frequency has been obtained for a lower level of total harmonic distortion and switching losses. Diode-clamped, three-phase topology is considered for study. A sinusoidal PWM technique is used to control the switches of the inverter. Simulation study confirms the reduction in harmonic distortion and switching losses as the number of the levels increases.

The article profiles technology company Hewlett-Packard (HP). It offers information focusing on the company's decision sciences solutions. HP includes three business groups which are Personal Systems Group, Imaging & Prining Group, and Technology Solutions Group. It also explores the role of the HP Decision Techonolgy Team and HP Laboratories (HPL) which delivers breakthrough and advanced technologies. The team addresses product portfolio management, marketing mix modeling, and enterprise risk management.

Non–heart-beating donor (NHBD) livers are an untapped source with the potential to provide relief to the current donor shortage problem. Hypothermic machine perfusion (MP) has the potential to reclaim and preserve these marginal donor organs.

The 'disintermediation' hypothesis remains a provocative proposition emerging from early literature on electronic commerce. Considerable anecdotal evidence supports the 'disintermediation' hypothesis, but limited empirical data on electronic commerce makes it difficult to test. Transaction cost analysis, search cost analysis and product characteristic analysis have been used as conceptual frameworks, with the main focus of these analyses being changes in market efficiency, prices and distribution of surplus among consumers and producers. Our analysis indicates that electronic commerce provides a nearly costless and fast alternative to coordination, communication and exchange functions. Until suitable institutions emerge to replace functions provided by middlemen, complete 'disintermediation' is not expected. We narrate five case studies to counter the 'disintermediation' hypothesis.

Islanding is a condition in which a microgrid or a portion of power grid, consisting of distributed generation (DG) sources, converter, and load, gets disconnected from the utility grid. Under this condition the DG sources in a microgrid must switch to a voltage control mode, in order to provide constant voltage to local loads. In grid connected mode, the microgrid works as current controller and injects power to the main grid, depending on the power generation and local load with suitable market policies. Providing constant voltage at a stable frequency with proper synchronization amongst each DG in a microgrid is a challenge. The complexity of such grid requires careful study and analysis before actual implementation. These challenges of microgrid are addressed using real time OPAL-RT simulation technology. Thus the paper describes an islanded microgrid with master slave controller for power balance, voltage/frequency regulation, and synchronization. Based on an advanced real-time platform named Real-Time Laboratory (RT-LAB), the impacts of the micro sources, load, and converters in an islanded microgrid is studied in this paper. The effectiveness of the proposed controller is analyzed through experimental results under balanced/unbalanced nonlinear loads condition.

Static excitation system (SES) has been implemented in a specially designed synchronous machine installed in a testing laboratory. This is a large capacity single machine operated in dual mode (i.e., motor or generator) with the help of static sources. It is well known that bearings of the rotating machines are vulnerable to the effects of the shaft voltages caused by the static sources. Shaft voltage is the prime concern for this special machine too due to SES. To find out the exact cause of the shaft voltage, SES of this machine has been modelled with Power Systems software. Various waveforms drawn from the model are validated through computer simulations and actual laboratory tests. Sources of shaft voltages are also analysed thereafter with the FFT analysis of the rotor voltage and current waveforms.

Provides information on a man-made biodegradable textile fiber called birla viscose. Trend in shifting of the production base of viscose staple fiber; Popularity of spun-shade; Development of a Central Export Marketing Cell in Bangkok, Thailand.