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High performance control of AC drives with MATLAB/Simulink models
A comprehensive guide to understanding AC machines with exhaustive simulation models to practice design and controlNearly seventy percent of the electricity generated worldwide is used by electrical motors. Worldwide, huge research efforts are being made to develop commercially viable three- and multi-phase motor drive systems that are economically and technically feasible.Focusing on the most popular AC machines used in industry - induction machine and permanent magnet synchronous machine - this book illustrates advanced control techniques and topologies in practice and recently deployed. Examples are drawn from important techniques including Vector Control, Direct Torque Control, Nonlinear Control, Predictive Control, multi-phase drives and multilevel inverters.Key features include:systematic coverage of the advanced concepts of AC motor drives with and without output filter;discussion on the modelling, analysis and control of three- and multi-phase AC machine drives, including the recently developed multi-phase-phase drive system and double fed induction machine;description of model predictive control applied to power converters and AC drives, illustrated together with their simulation models;end-of-chapter questions, with answers and PowerPoint slides available on the companion website www.wiley.com/go/aburub_controlThis book integrates a diverse range of topics into one useful volume, including most the latest developments. It provides an effective guideline for students and professionals on many vital electric drives aspects. It is an advanced textbook for final year undergraduate and graduate students, and researchers in power electronics, electric drives and motor control. It is also a handy tool for specialists and practicing engineers wanting to develop and verify their own algorithms and techniques.
eBook
Modern power electronics and AC drives
\"A clear understanding of power electronics and AC drives is crucially important in a wide range of modern systems, from household appliances to automated factories and it requires cross-disciplinary expertise that many engineers lack. Now, in Modern Power Electronics and AC Drives, one of the world's leading experts covers every aspect of the topic, including crucial innovations such as artificial intelligence, advanced estimation, and sensorless control. This book is not only important as an advanced reference but also covers the material for one senior-level and two graduate-level courses.\"--Jacket.
Book
High-voltage output triboelectric nanogenerator with DC/AC optimal combination method
The high-voltage power source is one of the important research directions of triboelectric nanogenerator (TENG). In this paper, a high-voltage output TENG (HVO-TENG) is proposed with direct current/alternating current (DC/AC) optimal combination method for wind energy harvesting. Through the optimal design of a direct current generation unit (DCGU) and an alternating current generation unit (ACGU), the HVO-TENG can produce DC voltage of 21.5 kV and AC voltage of 200 V, simultaneously. The HVO-TENG can continuously illuminate more than 6,000 light emitting diodes (LEDs), which is enough to drive more possible applications of TENG. Besides, this paper explored application experiments on HVO-TENG. Demonstrative experiments indicate that the high-voltage DC output is used for producing ozone, while the AC output can light up ultraviolet (UV) LEDs. The HVO-TENG can increase the ozone concentration (
C
) in an airtight container to 3 parts per million (ppm) after 7 h and continuously light up UV LEDs. All these demonstrations verify that the HVO-TENG has important guiding significance for designing high performance TENG.
Journal Article
Disruption and rescue of interareal theta phase coupling and adaptive behavior
Rescuing executive functions in people with neurological and neuropsychiatric disorders has been a major goal of psychology and neuroscience for decades. Innovative computer-training regimes for executive functions have made tremendous inroads, yet the positive effects of training have not always translated into improved cognitive functioning and often take many days to emerge. In the present study, we asked whether it was possible to immediately change components of executive function by directly manipulating neural activity using a stimulation technology called high-definition transcranial alternating current stimulation (HD-tACS). Twenty minutes of inphase stimulation over medial frontal cortex (MFC) and right lateral prefrontal cortex (lPFC) synchronized theta (∼6 Hz) rhythms between these regions in a frequency and spatially specific manner and rapidly improved adaptive behavior with effects lasting longer than 40 min. In contrast, antiphase stimulation in the same individuals desynchronized MFC-lPFC theta phase coupling and impaired adaptive behavior. Surprisingly, the exogenously driven impairments in performance could be instantly rescued by reversing the phase angle of alternating current. The results suggest executive functions can be rapidly upor down-regulated by modulating theta phase coupling of distant frontal cortical areas and can contribute to the development of tools for potentially normalizing executive dysfunction in patient populations.
Journal Article
Development of intelligent hybrid controller for torque ripple minimization in electric drive system with adaptive flux estimator: An experimental case study
In order to ensure optimal performance of permanent magnet synchronous motors (PMSMs) across many technical applications, it is imperative to minimize torque fluctuations and reduce total harmonic distortion (THD) in stator currents. Hence, this study proposes the utilization of an adaptive flux estimator (AFE) in conjunction with an Intelligent Hybrid Controller (IHC) to mitigate the ripples and total harmonic distortion (THD). The IHC system is constructed by integrating PI and fuzzy logic controllers (FLC) in a cascade configuration, alongside a new switching unit that facilitates automatic switching between the two controllers during various operations of the PMSM. AFE estimates accurate flux which is required to achieve ripple free high dynamic performance of the PMSM drive by using a limiter to fix the flux at reference flux value of the drive. The proposed controller with AFE has achieved its originality through the refinement of membership functions located at the center of the universe of discourse (UOD) and the enhancement of the switching function. These improvements have resulted in increased sensitivity in the proximity to the reference speed. The Fuzzy Logic Controller (FLC) demonstrates superior performance when operating in a transient state, whereas the Proportional-Integral (PI) controller of the proposed system exhibits satisfactory performance under steady-state situations. The efficacy of AFE with IHC is substantiated by the simulation and experimental analysis reported in this study. A significant reduction in both total harmonics distortion (THD) and torque ripples are found.
Journal Article
Investigating the Fuel Cell Performance Tradeoffs of Thick Catalyst Layers
Platinum group metal‐free (PGM‐free) catalysts are showing increasing performance and durability and are considered as viable candidates for replacing precious metal‐based catalysts for the oxygen reduction reaction (ORR) in fuel cells. Due to the low intrinsic activity and low active site density, large quantities of the PGM‐free catalysts are needed to obtain high performance. Consequently, the resulting high catalyst loadings induce several interesting and opposing phenomena, namely, lower ORR kinetic losses due to an increase in the number of active sites and much higher mass and charge transport losses. In this work, Fourier‐transformed alternating current voltammetry (FTacV) and electrochemical impedance spectroscopy (EIS) measurements are employed to systematically deconvolute the gains and losses to the activity due to the high loading of PGM‐free catalysts and relate the underlying processes to the observed fuel cell performance. EIS is analyzed via extraction of the distribution of relaxation times, obtaining a model‐free analysis of the physical processes in the cell. Combined with FTacV measurements, the obtained catalyst loading optimum from a mechanistic point of view is explained. The combined use of advanced alternating current techniques for the analysis of operating fuel cells is an important step toward the rational design of the catalyst layer. Understanding the impact of platinum group metal‐free oxygen reduction reaction catalyst layer thickness on fuel cells performance requires a combination of catalyst performance indicators and mass transport indicators, done in this work with combination of Fourier‐transformed alternating current voltammetry and distribution of relaxation times, showing the optimal catalyst loading for a Pajarito powder catalyst.
Journal Article
AC-induced coexisting asymmetric bursters in the improved Hindmarsh–Rose model
In this paper, an external alternating current (AC) is injected into the Hindmarsh–Rose (HR) neuron model to imitate the periodic stimulus effect on the membrane potential in the axon of a neuron and then an improved HR model is proposed. The AC equilibrium point and its stability in the proposed model are investigated theoretically, and the AC-induced coexisting behaviors of asymmetric bursters are revealed by MATLAB numerical simulations. Due to the injection of the AC item, the stability distribution of the unique AC equilibrium point in the improved HR model varies between unstable and stable intervals with the periodic evolution of the time, which leads to the emergence of various types of coexisting asymmetric bursters under different initial conditions of the bursting variable, such as hyperchaotic and periodic bursters, chaotic and periodic bursters, quasiperiodic and periodic bursters, two periodic bursters with different periodicities, and so on. Additionally, a simulated circuit model is designed and PSIM circuit simulations are performed to exhibit coexisting behaviors of asymmetric bursters, which effectively confirm the numerically simulated results.
Journal Article
Friends, not foes: Magnetoencephalography as a tool to uncover brain dynamics during transcranial alternating current stimulation
Brain oscillations are supposedly crucial for normal cognitive functioning and alterations are associated with cognitive dysfunctions. To demonstrate their causal role on behavior, entrainment approaches in particular aim at driving endogenous oscillations via rhythmic stimulation. Within this context, transcranial electrical stimulation, especially transcranial alternating current stimulation (tACS), has received renewed attention. This is likely due to the possibility of defining oscillatory stimulation properties precisely. Also, measurements comparing pre-tACS with post-tACS electroencephalography (EEG) have shown impressive modulations. However, the period during tACS has remained a blackbox until now, due to the enormous stimulation artifact. By means of application of beamforming to magnetoencephalography (MEG) data, we successfully recovered modulations of the amplitude of brain oscillations during weak and strong tACS. Additionally, we demonstrate that also evoked responses to visual and auditory stimuli can be recovered during tACS. The main contribution of the present study is to provide critical evidence that during ongoing tACS, subtle modulations of oscillatory brain activity can be reconstructed even at the stimulation frequency. Future tACS experiments will be able to deliver direct physiological insights in order to further the understanding of the contribution of brain oscillations to cognition and behavior.
Journal Article
Feasibility Study of Using Alternating Current Excitation to Obtain Electrodermal Activity with a Wearable System
This study investigates the feasibility of using a wearable system with full-wave alternating current (AC) excitation to measure electrodermal activity (EDA). Typically measured using direct current (DC) excitation, EDA is often affected by signal drift due to electrode–skin polarisation. To address this, a portable device was developed that applies fixed-amplitude, full-wave AC signals and records EDA under controlled conditions. The electrical behaviour of the skin was also simulated using a multilayer model to analyse current propagation at different frequencies. The experimental procedure was conducted with ten healthy participants under controlled conditions. Two stages were carried out: the first compared the similarity of the skin conductance level (SCL) between DC and half-wave alternating current (AC) signals; the second analysed signal stability and skin response at full-wave AC excitation. Compared to DC, full-wave AC excitation demonstrated reduced signal drift, greater temporal stability, and enhanced measurement of the skin’s capacitive response. These findings support the adoption of AC excitation for EDA measurement, especially in ambulatory and real-time biomechanical applications where signal reliability and stability are essential.
Journal Article