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Special Issue "Techniques of Control for Energy Optimization in Actuators, Motors and Power Generation Systems"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 October 2016).

Special Issue Editor

Guest Editor
Prof. Dr.-Ing. Paolo Mercorelli

Institute of Product and Process Innovation, Leuphana University of Lueneburg, 21339 Lueneburg, Germany
Website 1 | Website 2 | E-Mail
Phone: 0049-(0)4131-677.5571
Fax: 0049-(0)4131-677.5300
Interests: control systems; mechatronics; actuators; engines control; signal processing; wavelets; kalman filter; energy control

Special Issue Information

Dear Colleagues,

It is common sense that an intelligent administration of energy resources represents a unique way to respect the environment, and equally redistribute and reutilize resources. In today’s energy systems, control and optimisation techniques and algorithms play a decisive role. In fact, energy optimisation represents a crucial issue in smart grid/micro-grids energy flow, renewable energy, electrical and hybrid vehicles, as well as in traditional engines, energy storage devices, electrical motors, and in any kind of actuator, including alternative actuators. In term of energy, all these systems, from the biggest to the smallest, play an extremely important role. Any kind of small motors and actuators (electrical, hydraulic, pneumatic, etc.), which are devoted to the transformation of energy into movement, because of their massive application, should be considered in this process of global intelligent energy optimisation. This Special Issue of Energies will explore the latest developments in intelligent control algorithms and techniques dedicated to the optimal management of energy in the systems listed above, or in any kind of system in which an algorithm or a technique plays a decisive role in term of energy optimization and performance.

Prof. Dr.-Ing. Paolo Mercorelli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • control techniques and energy optimization in any kind of motors and actuators (electrical, pneumatic, electro-magnetic, mechanical, etc.);
  • control techniques and algorithms to optimize energy flow in smart/grid;
  • control techniques and algorithms to optimize operational conditions of wind turbines;
  • energetic optimization in intelligent drive assistants for electrical and hybrid vehicles;
  • techniques and algorithms for management in electrical batteries;
  • techniques and algorithms to control combustion engines, such as algorithm for knock control, lambda control, camless systems, etc.

Published Papers (18 papers)

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Research

Open AccessArticle
Hysteresis Analysis and Control of a Metal-Polymer Hybrid Soft Actuator
Energies 2017, 10(4), 508; https://doi.org/10.3390/en10040508
Received: 31 October 2016 / Revised: 11 March 2017 / Accepted: 13 March 2017 / Published: 8 April 2017
Cited by 4 | PDF Full-text (8864 KB) | HTML Full-text | XML Full-text
Abstract
The number of applications of stimulus-responsive polymers is growing at an impressive rate. The motivation of this contribution is to use a commercially available low-budget silver-coated polyamide (PA6) as a thermo-responsive metal-polymer hybrid soft actuator. Polyamide is a hygroscopic polymer; therefore, its mechanical [...] Read more.
The number of applications of stimulus-responsive polymers is growing at an impressive rate. The motivation of this contribution is to use a commercially available low-budget silver-coated polyamide (PA6) as a thermo-responsive metal-polymer hybrid soft actuator. Polyamide is a hygroscopic polymer; therefore, its mechanical and physical-chemical properties are affected by exposition to humidity or immersion in water. The effect of water absorption content on the PA6 and silver-coated PA6 monofilament properties, such as mass change and resistance, were evaluated. Moreover, the influence of swelling and shrinking effects on the surface morphology, caused by variations of moisture and water immersion, was investigated. Based on these variations, the dynamics of the resistance of the hybrid material were analyzed in the context of the proposed hysteresis model. An identification procedure of the hysteresis is presented along with an approximation of the upper and lower bound based on a constrained least square approach. A switching logic algorithm for this hybrid dynamic system is introduced, which makes it possible to structure the non-linear function in a switching mode. Finally, a non-linear integral sliding manifold is proposed and tested to control the resulting force of the actuator.hysteresis model. An identification procedure of the hysteresis is presented along with an approximation of the upper and lower bound based on a constrained least square approach. A switching logic algorithm for this hybrid dynamic system is introduced, which makes it possible to structure the non-linear function in a switching mode. Finally, a non-linear integral sliding manifold is proposed and tested to control the resulting force of the actuator. Full article
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Open AccessArticle
Research on Optimal Planning of Access Location and Access Capacity of Large-Scale Integrated Wind Power Plants
Energies 2017, 10(4), 442; https://doi.org/10.3390/en10040442
Received: 13 December 2016 / Revised: 18 March 2017 / Accepted: 21 March 2017 / Published: 1 April 2017
Cited by 1 | PDF Full-text (888 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a multi-objective optimal planning model of access location and access capacity for large-scale integrated wind power generation considering the mutual restriction between the planning of large-scale wind power plants and the planning of power system network. In this model, the [...] Read more.
This paper proposes a multi-objective optimal planning model of access location and access capacity for large-scale integrated wind power generation considering the mutual restriction between the planning of large-scale wind power plants and the planning of power system network. In this model, the power flow equilibrium degree, investment costs and active network loss are taken as the optimization goals. The improved differential evolution (IDE) algorithm is applied to calculate the Pareto optimal solution set of wind power’s access planning. With the solution results described by the Pareto pattern, all the alternative solutions are then ranked based on the entropy weight method and the final compromised solution is selected by the method of technique for order preference by similarity to ideal (TOPSIS). And the proposed optimal planning model is tested based on a practical planning need of large-scale integrated wind power generation in an actual power grid of China in 2020. The simulation results show that applied with the proposed optimization model and matching algorithm, the planning scheme of large-scale wind power’s access location and access capacity under complex and practical power system circumstances has been successfully optimized. Full article
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Open AccessArticle
Fault Tolerant and Optimal Control of Wind Turbines with Distributed High-Speed Generators
Energies 2017, 10(2), 149; https://doi.org/10.3390/en10020149
Received: 3 October 2016 / Revised: 10 January 2017 / Accepted: 11 January 2017 / Published: 24 January 2017
Cited by 4 | PDF Full-text (2064 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the control scheme of a distributed high-speed generator system with a total amount of 12 generators and nominal generator speed of 7000 min1 is studied. Specifically, a fault tolerant control (FTC) scheme is proposed to keep the turbine [...] Read more.
In this paper, the control scheme of a distributed high-speed generator system with a total amount of 12 generators and nominal generator speed of 7000 min 1 is studied. Specifically, a fault tolerant control (FTC) scheme is proposed to keep the turbine in operation in the presence of up to four simultaneous generator faults. The proposed controller structure consists of two layers: The upper layer is the baseline controller, which is separated into a partial load region with the generator torque as an actuating signal and the full-load operation region with the collective pitch angle as the other actuating signal. In addition, the lower layer is responsible for the fault diagnosis and FTC characteristics of the distributed generator drive train. The fault reconstruction and fault tolerant control strategy are tested in simulations with several actuator faults of different types. Full article
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Open AccessArticle
Modeling and Maximum Power Point Tracking Control of Wind Generating Units Equipped with Permanent Magnet Synchronous Generators in Presence of Losses
Energies 2017, 10(1), 102; https://doi.org/10.3390/en10010102
Received: 27 September 2016 / Revised: 20 December 2016 / Accepted: 3 January 2017 / Published: 15 January 2017
Cited by 14 | PDF Full-text (5737 KB) | HTML Full-text | XML Full-text
Abstract
This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results [...] Read more.
This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results is proposed. Moreover, some analytical assessments are detailed on typical control schemes for fully rated wind turbine generators, thereby highlighting how active power losses play a fundamental role in the effectiveness of the wind generator control algorithm. Finally, the paper proposes analytical criteria to design the structure and the parameters of the regulators of the wind generator control scheme. Simulations performed with Digsilent Power Factory validated the proposed procedure, highlighting the impact of active power losses on the characterization of the initial steady state and that the simplifying assumptions done in order to synthesize the controllers are consistent with the complete modeling performed by the aforementioned power system simulator. Full article
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Open AccessArticle
Tie-Line Bias Control Applicability to Load Frequency Control for Multi-Area Interconnected Power Systems of Complex Topology
Energies 2017, 10(1), 78; https://doi.org/10.3390/en10010078
Received: 14 October 2016 / Revised: 28 December 2016 / Accepted: 28 December 2016 / Published: 11 January 2017
Cited by 5 | PDF Full-text (842 KB) | HTML Full-text | XML Full-text
Abstract
The tie-line bias control (TBC) method has been widely used in the load frequency control (LFC) of multi-area interconnected systems. However, it should be questioned whether the conventional TBC can still apply to LFC when considering the complication of structures of power systems. [...] Read more.
The tie-line bias control (TBC) method has been widely used in the load frequency control (LFC) of multi-area interconnected systems. However, it should be questioned whether the conventional TBC can still apply to LFC when considering the complication of structures of power systems. LFC, in essence, is to stabilize system frequency/tie-line power by controlling controlled outputs’ area control error (ACE). In this paper, relations between LFC control variables and controlled outputs are expressed as a system of equations, based on which an exemplary ring network is studied. Sufficient and necessary conditions for TBC applicability is presented, and a novel LFC mode is proposed for a general ring network where TBC cannot work. Finally, TBC applicability to multi-area systems with general topology is studied, and a general LFC mode is proposed for systems where TBC is not definitely applicable, thus rendering routines that may guide LFC design of future power systems with more complex topologies. Full article
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Open AccessArticle
Power Control of Low Frequency AC Transmission Systems Using Cycloconverters with Virtual Synchronous Generator Control
Energies 2017, 10(1), 34; https://doi.org/10.3390/en10010034
Received: 6 September 2016 / Revised: 28 November 2016 / Accepted: 19 December 2016 / Published: 28 December 2016
Cited by 4 | PDF Full-text (4560 KB) | HTML Full-text | XML Full-text
Abstract
This paper is focused on the application of a multi-terminal line-commutated converter-type low frequency AC transmission system (MTLF) using a cycloconverter by applying a new power control scheme for multi-terminal operation. With the virtual synchronous generator (VSG) control scheme, the transmitting power among [...] Read more.
This paper is focused on the application of a multi-terminal line-commutated converter-type low frequency AC transmission system (MTLF) using a cycloconverter by applying a new power control scheme for multi-terminal operation. With the virtual synchronous generator (VSG) control scheme, the transmitting power among the multi-terminal system can be accomplished without a communication link for frequency synchronization in each terminal. The details of the proposed control scheme are explained in order to understand the advantages of this method. The configuration of a two-phase low frequency AC transmission system (LFAC) is adopted to examine with the proposed control scheme. Simulation results are provided to illustrate the proposed control scheme with respect to the LFAC system’s performance. Full article
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Open AccessArticle
A Causal and Real-Time Capable Power Management Algorithm for Off-Highway Hybrid Propulsion Systems
Energies 2017, 10(1), 10; https://doi.org/10.3390/en10010010
Received: 28 September 2016 / Revised: 8 December 2016 / Accepted: 16 December 2016 / Published: 26 December 2016
PDF Full-text (3359 KB) | HTML Full-text | XML Full-text
Abstract
Hybrid propulsion systems allow for a reduction of fuel consumption and pollutant emissions of future off-highway applications. A challenging aspect of a hybridization is the larger number of system components that further increases both the complexity and the diversification of such systems. Hence, [...] Read more.
Hybrid propulsion systems allow for a reduction of fuel consumption and pollutant emissions of future off-highway applications. A challenging aspect of a hybridization is the larger number of system components that further increases both the complexity and the diversification of such systems. Hence, beside a standardization on the hardware side for off-highway systems, a high flexibility and modularity of the control schemes is required to employ them in as many different applications as possible. In this paper, a causal optimization-based power management algorithm is introduced to control the power split between engine and electric machine in a hybrid powertrain. The algorithm optimizes the power split to achieve the maximum power supply efficiency and, thereby, considers the energy cost for maintaining the battery charge. Furthermore, the power management provides an optional function to control the battery state of charge in such a way that a target value is attained. In a simulation case study, the potential and the benefits of the proposed power management for the hybrid powertrain—aiming at a reduction of the fuel consumption of a DMU (diesel multiple unit train) operated on a representative track—will be shown. Full article
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Open AccessArticle
Simplified Minimum Copper Loss Remedial Control of a Five-Phase Fault-Tolerant Permanent-Magnet Vernier Machine under Short-Circuit Fault
Energies 2016, 9(11), 860; https://doi.org/10.3390/en9110860
Received: 9 July 2016 / Revised: 2 October 2016 / Accepted: 13 October 2016 / Published: 25 October 2016
Cited by 4 | PDF Full-text (4008 KB) | HTML Full-text | XML Full-text
Abstract
A fault-tolerant permanent-magnet vernier (FT-PMV) machine incorporates the merits of high fault-tolerant capability and high torque density. In this paper, a new remedial control is proposed for a five-phase FT-PMV machine with short-circuit fault of stator windings. Based on the principle of copper [...] Read more.
A fault-tolerant permanent-magnet vernier (FT-PMV) machine incorporates the merits of high fault-tolerant capability and high torque density. In this paper, a new remedial control is proposed for a five-phase FT-PMV machine with short-circuit fault of stator windings. Based on the principle of copper loss minimization, the aims of the proposed control strategy are to keep magnetic motive force (MMF) unchanged and minimize torque ripple. The proposed remedial control strategy contains two parts. Firstly, the remedial currents of the healthy phases are used to compensate for the ripple of MMF caused by the short-circuit current. Secondly, an open-circuit fault-tolerant control strategy is used to compensate for the lack of normal torque in the fault phase. Finally, the vector sum of two parts is adopted to derive the remedial currents. The final expression of the proposed remedial current is simpler than that than these previous methods. In addition, the proposed remedial currents are sinusoidal, which can reduce the reactive component in instantaneous power produced by pulsating torque and iron loss of a sine back-EMF machine. A FT-PMV prototype is built. The simulations and the experiments verify the effectiveness of the proposed strategy. Full article
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Open AccessArticle
Cost Analysis Method for Estimating Dynamic Reserve Considering Uncertainties in Supply and Demand
Energies 2016, 9(10), 845; https://doi.org/10.3390/en9100845
Received: 8 August 2016 / Revised: 30 September 2016 / Accepted: 12 October 2016 / Published: 20 October 2016
Cited by 4 | PDF Full-text (3200 KB) | HTML Full-text | XML Full-text
Abstract
The use of appropriate hourly reserve margins can maintain power system security by balancing supply and demand in the presence of errors in the forecast demand, generation outages, or errors in the forecast of wind power generation. Because the cost of unit commitment [...] Read more.
The use of appropriate hourly reserve margins can maintain power system security by balancing supply and demand in the presence of errors in the forecast demand, generation outages, or errors in the forecast of wind power generation. Because the cost of unit commitment increases with larger reserve margins, cost analysis to determine the most economical reserve margin is an important issue in power system operation. Here, we define the “short-term reliability of balance” and describe a method to determine the reserve margin based on the short-term reliability of balance. We describe a case study, in which we calculate the reserve margin using this method with various standards of short-term reliability of balance. A cost analysis is then performed to determine the most economic standard, and a comparison between our method and a conventional method is carried out. The results show that our method with an economic short-term reliability of balance enables more reliable and efficient operation of the power system. Moreover, with an hourly reserve margin, we show that an increase in wind power generation can result in a significant decrease in the operating cost, which makes wind power generation economically viable. Full article
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Open AccessArticle
A Study on Magnetic Decoupling of Compound-Structure Permanent-Magnet Motor for HEVs Application
Energies 2016, 9(10), 819; https://doi.org/10.3390/en9100819
Received: 6 September 2016 / Revised: 28 September 2016 / Accepted: 11 October 2016 / Published: 14 October 2016
Cited by 5 | PDF Full-text (5504 KB) | HTML Full-text | XML Full-text
Abstract
The compound-structure permanent-magnet (CSPM) motor is used for an electrical continuously-variable transmission (E-CVT) in a hybrid electric vehicle (HEV). It can make the internal combustion engine (ICE) independent of the road loads and run in the high efficiency area to improve the fuel [...] Read more.
The compound-structure permanent-magnet (CSPM) motor is used for an electrical continuously-variable transmission (E-CVT) in a hybrid electric vehicle (HEV). It can make the internal combustion engine (ICE) independent of the road loads and run in the high efficiency area to improve the fuel economy and reduce the emissions. This paper studies the magnetic coupling of a new type of CSPM motor used in HEVs. Firstly, through the analysis of the parameter matching with CSPM in the HEV, we receive the same dynamic properties’ design parameters between the CSPM motor and the THS (Toyota Hybrid System) of the Toyota Prius. Next, we establish the equivalent magnetic circuit model of the overall and the secondary model considering the tangential and radial flux distribution in the outer rotor of the CSPM motor. Based on these two models, we explore the internal magnetic coupling rule of the CSPM motor. Finally, finite element method analysis in 2D-ansoft is used to analyze the magnetic field distribution of the CSPM motor in different operation modes. By the result of the finite element method analysis, the internal magnetic decoupling scheme is put forward, laying the theoretical foundation for the further application of the CSPM motor in HEVs. Full article
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Open AccessArticle
Operation Modeling of Power Systems Integrated with Large-Scale New Energy Power Sources
Energies 2016, 9(10), 810; https://doi.org/10.3390/en9100810
Received: 2 August 2016 / Revised: 20 September 2016 / Accepted: 30 September 2016 / Published: 11 October 2016
Cited by 5 | PDF Full-text (1566 KB) | HTML Full-text | XML Full-text
Abstract
In the most current methods of probabilistic power system production simulation, the output characteristics of new energy power generation (NEPG) has not been comprehensively considered. In this paper, the power output characteristics of wind power generation and photovoltaic power generation are firstly analyzed [...] Read more.
In the most current methods of probabilistic power system production simulation, the output characteristics of new energy power generation (NEPG) has not been comprehensively considered. In this paper, the power output characteristics of wind power generation and photovoltaic power generation are firstly analyzed based on statistical methods according to their historical operating data. Then the characteristic indexes and the filtering principle of the NEPG historical output scenarios are introduced with the confidence level, and the calculation model of NEPG’s credible capacity is proposed. Based on this, taking the minimum production costs or the best energy-saving and emission-reduction effect as the optimization objective, the power system operation model with large-scale integration of new energy power generation (NEPG) is established considering the power balance, the electricity balance and the peak balance. Besides, the constraints of the operating characteristics of different power generation types, the maintenance schedule, the load reservation, the emergency reservation, the water abandonment and the transmitting capacity between different areas are also considered. With the proposed power system operation model, the operation simulations are carried out based on the actual Northwest power grid of China, which resolves the new energy power accommodations considering different system operating conditions. The simulation results well verify the validity of the proposed power system operation model in the accommodation analysis for the power system which is penetrated with large scale NEPG. Full article
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Open AccessArticle
Feedback Linearization Controller for a Wind Energy Power System
Energies 2016, 9(10), 771; https://doi.org/10.3390/en9100771
Received: 14 June 2016 / Revised: 10 September 2016 / Accepted: 19 September 2016 / Published: 23 September 2016
Cited by 4 | PDF Full-text (1527 KB) | HTML Full-text | XML Full-text
Abstract
This paper deals with the control of a doubly-fed induction generator (DFIG)-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with back-to-back [...] Read more.
This paper deals with the control of a doubly-fed induction generator (DFIG)-based variable speed wind turbine power system. A system of eight ordinary differential equations is used to model the wind energy conversion system. The generator has a wound rotor type with back-to-back three-phase power converter bridges between its rotor and the grid; it is modeled using the direct-quadrature rotating reference frame with aligned stator flux. An input-state feedback linearization controller is proposed for the wind energy power system. The controller guarantees that the states of the system track the desired states. Simulation results are presented to validate the proposed control scheme. Moreover, further simulation results are shown to investigate the robustness of the proposed control scheme to changes in some of the parameters of the system. Full article
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Open AccessArticle
Curtailment in a Highly Renewable Power System and Its Effect on Capacity Factors
Energies 2016, 9(7), 510; https://doi.org/10.3390/en9070510
Received: 26 April 2016 / Revised: 2 June 2016 / Accepted: 9 June 2016 / Published: 30 June 2016
Cited by 21 | PDF Full-text (17280 KB) | HTML Full-text | XML Full-text
Abstract
The capacity factor of a power plant is the ratio of generation over its potential generation. It is an important measure to describe wind and solar resources. However, the fluctuating nature of renewable power generation makes it difficult to integrate all generation at [...] Read more.
The capacity factor of a power plant is the ratio of generation over its potential generation. It is an important measure to describe wind and solar resources. However, the fluctuating nature of renewable power generation makes it difficult to integrate all generation at times. Whenever generation exceeds the load, curtailment or storage of energy is required. With increasing renewable shares in the power system, the level of curtailment will further increase. In this work, the influence of the curtailment on the capacity factors for a highly renewable German power system is studied. An effective capacity factor is introduced, and the implications for the distribution of renewable power plants are discussed. Three years of highly-resolved weather data were used to model wind and solar power generation. Together with historical load data and a transmission model, a possible future German power system was simulated. It is shown that effective capacity factors for unlimited transmission are strongly reduced by up to 60% (wind) and 70% (photovoltaics) and therefore of limited value in a highly renewable power system. Furthermore, the results demonstrate that wind power benefits more strongly from a reinforced transmission grid than photovoltaics (PV) does. Full article
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Open AccessArticle
Sliding Mode Variable Structure Control of a Bearingless Induction Motor Based on a Novel Reaching Law
Energies 2016, 9(6), 452; https://doi.org/10.3390/en9060452
Received: 12 April 2016 / Revised: 26 May 2016 / Accepted: 27 May 2016 / Published: 13 June 2016
Cited by 8 | PDF Full-text (2904 KB) | HTML Full-text | XML Full-text
Abstract
In order to improve the performance of the Bearingless Induction Motor (BIM) under large disturbances (such as parameter variations and load disturbances), an adaptive variable-rated sliding mode controller (ASMC) is designed to obtain better performance of the speed regulation system. Firstly, the L [...] Read more.
In order to improve the performance of the Bearingless Induction Motor (BIM) under large disturbances (such as parameter variations and load disturbances), an adaptive variable-rated sliding mode controller (ASMC) is designed to obtain better performance of the speed regulation system. Firstly, the L 1 norm of state variables is applied to the conventional exponential reaching law and an adaptive variable-rated exponential reaching law is proposed to reduce system chattering and improve bad convergence performance of the sliding mode variable structure. Secondly, an integral sliding-mode hyper plane is produced according to the speed error in speed regulation system of BIM. Current signal is extracted by the combination of the sliding-mode hyper plane, the electromagnetic torque and the equation of motion. Finally, the feedback speed can adjust operating state adaptively according to speed error and make system chattering-free moving. The simulation and experiment results show that the proposed ASMC can not only enhance the robustness of the system’s uncertainties, but also improve the dynamic performance and suppress system chattering. Full article
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Open AccessArticle
Simultaneous Optimization of Topology and Component Sizes for Double Planetary Gear Hybrid Powertrains
Energies 2016, 9(6), 411; https://doi.org/10.3390/en9060411
Received: 28 February 2016 / Revised: 10 May 2016 / Accepted: 20 May 2016 / Published: 26 May 2016
Cited by 13 | PDF Full-text (5361 KB) | HTML Full-text | XML Full-text
Abstract
Hybrid powertrain technologies are successful in the passenger car market and have been actively developed in recent years. Optimal topology selection, component sizing, and controls are required for competitive hybrid vehicles, as multiple goals must be considered simultaneously: fuel efficiency, emissions, performance, and [...] Read more.
Hybrid powertrain technologies are successful in the passenger car market and have been actively developed in recent years. Optimal topology selection, component sizing, and controls are required for competitive hybrid vehicles, as multiple goals must be considered simultaneously: fuel efficiency, emissions, performance, and cost. Most of the previous studies explored these three design dimensions separately. In this paper, two novel frameworks combining these three design dimensions together are presented and compared. One approach is nested optimization which searches through the whole design space exhaustively. The second approach is called enhanced iterative optimization, which executes the topology optimization and component sizing alternately. A case study shows that the later method can converge to the global optimal design generated from the nested optimization, and is much more computationally efficient. In addition, we also address a known issue of optimal designs: their sensitivity to parameters, such as varying vehicle weight, which is a concern especially for the design of hybrid buses. Therefore, the iterative optimization process is applied to design a robust multi-mode hybrid electric bus under different loading scenarios as the final design challenge of this paper. Full article
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Open AccessArticle
Aerodynamic Analysis and Three-Dimensional Redesign of a Multi-Stage Axial Flow Compressor
Energies 2016, 9(4), 296; https://doi.org/10.3390/en9040296
Received: 14 September 2015 / Revised: 29 March 2016 / Accepted: 11 April 2016 / Published: 16 April 2016
Cited by 3 | PDF Full-text (10477 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes the introduction of three-dimension (3-D) blade designs into a 5-stage axial compressor with multi-stage computational fluid dynamic (CFD) methods. Prior to a redesign, a validation study is conducted for the overall performance and flow details based on full-scale test data, [...] Read more.
This paper describes the introduction of three-dimension (3-D) blade designs into a 5-stage axial compressor with multi-stage computational fluid dynamic (CFD) methods. Prior to a redesign, a validation study is conducted for the overall performance and flow details based on full-scale test data, proving that the multi-stage CFD applied is a relatively reliable tool for the analysis of the follow-up redesign. Furthermore, at the near stall point, the aerodynamic analysis demonstrates that significant separation exists in the last stator, leading to the aerodynamic redesign, which is the focus of the last stator. Multi-stage CFD methods are applied throughout the three-dimensional redesign process for the last stator to explore their aerodynamic improvement potential. An unconventional asymmetric bow configuration incorporated with leading edge re-camber and re-solidity is employed to reduce the high loss region dominated by the mainstream. The final redesigned version produces a 13% increase in the stall margin while maintaining the efficiency at the design point. Full article
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Open AccessArticle
Control and Optimization of a Variable-Pitch Quadrotor with Minimum Power Consumption
Energies 2016, 9(4), 232; https://doi.org/10.3390/en9040232
Received: 15 February 2016 / Revised: 16 March 2016 / Accepted: 18 March 2016 / Published: 24 March 2016
Cited by 2 | PDF Full-text (5215 KB) | HTML Full-text | XML Full-text
Abstract
Recently, there has been a rapid growth of interest in quadrotors with electric variable-pitch propellers. The control and optimization of such propellers are important factors for improving the flight performance of the vehicles. Therefore, the steady-state identification method to estimate the parameters of [...] Read more.
Recently, there has been a rapid growth of interest in quadrotors with electric variable-pitch propellers. The control and optimization of such propellers are important factors for improving the flight performance of the vehicles. Therefore, the steady-state identification method to estimate the parameters of the mathematical model of the electric variable-pitch propeller is developed. The steady-state control and optimization scheme with minimum power consumption and the adaptive compensation scheme for the variable-pitch propeller are then proposed, based on which the response performance of the lift force produced by the variable-pitch propeller can be greatly improved by using a cascade compensation scheme. Furthermore, the direct lift-based flight control strategy is presented, which can significantly contribute to the improvement of the flight performance, precisely because the roll, pitch, yaw and vertical channels of the variable-pitch quadrotor are approximately linearized and completely decoupled from each other in this case. The experimental results demonstrate that both the endurance performance and the positioning accuracy of the variable-pitch quadrotor are improved simultaneously by using the proposed method with minimum power consumption. Full article
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Open AccessArticle
A Multi-Objective Optimization Framework for Offshore Wind Farm Layouts and Electric Infrastructures
Energies 2016, 9(3), 216; https://doi.org/10.3390/en9030216
Received: 2 November 2015 / Revised: 1 March 2016 / Accepted: 4 March 2016 / Published: 18 March 2016
Cited by 11 | PDF Full-text (7441 KB) | HTML Full-text | XML Full-text
Abstract
Current offshore wind farms (OWFs) design processes are based on a sequential approach which does not guarantee system optimality because it oversimplifies the problem by discarding important interdependencies between design aspects. This article presents a framework to integrate, automate and optimize the design [...] Read more.
Current offshore wind farms (OWFs) design processes are based on a sequential approach which does not guarantee system optimality because it oversimplifies the problem by discarding important interdependencies between design aspects. This article presents a framework to integrate, automate and optimize the design of OWF layouts and the respective electrical infrastructures. The proposed framework optimizes simultaneously different goals (e.g., annual energy delivered and investment cost) which leads to efficient trade-offs during the design phase, e.g., reduction of wake losses vs collection system length. Furthermore, the proposed framework is independent of economic assumptions, meaning that no a priori values such as the interest rate or energy price, are needed. The proposed framework was applied to the Dutch Borssele areas I and II. A wide range of OWF layouts were obtained through the optimization framework. OWFs with similar energy production and investment cost as layouts designed with standard sequential strategies were obtained through the framework, meaning that the proposed framework has the capability to create different OWF layouts that would have been missed by the designers. In conclusion, the proposed multi-objective optimization framework represents a mind shift in design tools for OWFs which allows cost savings in the design and operation phases. Full article
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Energies EISSN 1996-1073 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
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