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Energy Efficient Actuators and Systems

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

Deadline for manuscript submissions: closed (31 January 2016) | Viewed by 91344

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Special Issue Editors

Prof. Dr. Timothy Gordon

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Guest Editor

School of Engineering, University of Lincoln, Lincoln LN6 7TS, UK
Interests: vehicle control systems; vehicle dynamics; active safety; collision avoidance; autonomous systems including self-driving cars
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Jihong Wang

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Guest Editor

School of Engineering, University of Warwick, Coventry CV4 7AL, UK
Interests: Power system modelling, control and monitoring, including large scale power plant modelling and control; energy efficient actuators and systems; nonlinear system control theory with industrial applications

Dr. Jacek Wojcik

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Guest Editor

School of Engineering, University of Warwick, Coventry CV4 7AL, UK
Interests: Supercritical Power Plants—simulation and control; Power System Analysis, Modelling, Control and Monitoring; Renewable Energy Sources integration with the Grid

Special Issue Information

Dear Colleagues,

It is well recognized that saving energy through efficient design and operation of engineering systems is as important as developing clean and renewable energy sources. Both types of technologies contribute to emission reductions and sustainable economic development. Energy saving can be achieved through optimal design and control of actuators and systems, ranging from improved components to large-scale systems integration and use of “big data”. This Special Issue is dedicated to new research findings and development in this broad area of energy efficiency in engineering systems. Topics for publication include, but are not limited to:

design of energy-efficient electrical, hydraulic and pneumatic actuators/drives
energy-efficient control of electrical, hydraulic and pneumatic actuator systems
energy efficient control of power generation systems (both conventional and novel)
control and management of thermal systems
design and operation of energy storage systems
innovative design in actuators
analysis tools for evaluating and improving energy efficiency
energy saving in large-scale systems (manufacturing, transportation, etc.)

Prof.Dr. Jihong Wang
Prof. Dr. Timothy Gordon
Dr. Jacek Wojcik
Guest Editors

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Keywords

energy efficient actuators
energy efficient systems
energy optimal control
optimization
energy storage
power generation
renewable energy
thermal systems
modelling and simulation

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Published Papers (12 papers)

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Research

5467 KiB

Open AccessArticle

Dynamic Energy Management of Hybrid Energy Storage Systems with a Hierarchical Structure

by Chang Ye, Shihong Miao, Qi Lei and Yaowang Li

Energies 2016, 9(6), 395; https://doi.org/10.3390/en9060395 - 24 May 2016

Cited by 20 | Viewed by 5271

Abstract

In power system control unicontrol with single storage units or centralized control with multiple storage units to meet different level targets is challenging. Considering the charge and discharge characteristics of storage devices, this paper proposes a hierarchical configuration structure of a battery and supercapacitor mixed storage scenario, and develops a convenient control method for accessing various DC loads and can central manage mass batteries in one place. Aiming at the optimal management of large scale battery storage, the paper proposes a three-layer battery hierarchical control structure and the control objects and control circuits are discussed. Simulation studies are used to verify the control effect of the hierarchical storage system and the results show that the strategy can effectively decrease photovoltaic output fluctuation. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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5852 KiB

Open AccessArticle

Numerical Study of Solidification in a Plate Heat Exchange Device with a Zigzag Configuration Containing Multiple Phase-Change-Materials

by Peilun Wang, Dacheng Li, Yun Huang, Xingang Zheng, Yi Wang, Zhijian Peng and Yulong Ding

Energies 2016, 9(6), 394; https://doi.org/10.3390/en9060394 - 24 May 2016

Cited by 22 | Viewed by 5464

Abstract

Latent heat thermal energy storage (TES) plays an important role in the advocation of TES in contrast to sensible energy storage because of the large storage energy densities per unit mass/volume possible at a nearly constant thermal energy. In the current study, a heat exchange device with a zigzag configuration containing multiple phase-change-materials (m-PCMs) was considered, and an experimental system was built to validate the model for a single PCM. A two-dimensional numerical model was developed using the ANSYS Fluent 14.0 software program. The energy fractions method was put forward to calculate the average Ste number and the influence of Re and Ste numbers on the discharge process were studied. The influence of phase change temperature among m-PCMs on the solidification process has also been studied. A new boundary condition was defined to determine the combined effect of the Re and Ste numbers on the discharging process. The modelling results show that for a given input power, the Ste (or Re) number has a significant impact on the discharging process; however, the period value of inlet velocity has almost no impact on it. Besides, the zigzag plate with m-PCMs has a good impact on the temperature shock as “filter action” in the discharging process. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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4609 KiB

Open AccessArticle

Modeling for Three-Pole Radial Hybrid Magnetic Bearing Considering Edge Effect

by Huangqiu Zhu, Shuling Ding and Jintao Jv

Energies 2016, 9(5), 345; https://doi.org/10.3390/en9050345 - 6 May 2016

Cited by 14 | Viewed by 4552

Abstract

In order to overcome the shortcoming of magnetic bearings whereby general mathematical models of the radial suspension forces cannot be accurately established, a mathematical model considering the edge effect is set up. The configuration, operation principle and flux distribution features of a three-pole radial hybrid magnetic bearing (HMB) are analyzed in this paper. The magnetic field division method is employed to calculate the permeance of different regions around the end portion of poles. The total permeance of a single pole is composed of the permeance of the regions. Then, an accurate mathematical model of the radial suspension forces considering the edge effect is deduced by the equivalent magnetic circuit method. From the modeling procedures, it can be seen that the edge effect calculation is only related to the configuration and parameters of the magnetic poles, and is isolated with the other configurations and parameters of the three-pole radial HMB, therefore, the mathematical model is proved universal for calculating different suspension forces of hybrid magnetic bearings. A finite element analysis (FEA) simulation and three-pole radial HMB experiments are performed. The error between the theoretical calculation values and the FEA simulation values of the suspension forces is less than 5%, and the error between theoretical calculation value and experimental value of suspension forces is less than 7%. The comparison between the results of the theoretical calculation, FEA simulation and experiments has verified that the established mathematical model can accurately calculate the suspension forces. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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4755 KiB

Open AccessArticle

Energy Transformations in a Self-Excited Switched Reluctance Generator

by Abelardo Martinez-Iturbe, Francisco Jose Perez-Cebolla, Bonifacio Martín-del-Brío, Carlos Bernal and Antonio Bono-Nuez

Energies 2016, 9(5), 321; https://doi.org/10.3390/en9050321 - 28 Apr 2016

Cited by 3 | Viewed by 5600

Abstract

Wind generation systems require mechanisms that allow optimal adaptation of the generator to varying wind speed and to extract maximum energy from the wind. Robust and affordable high-performance methods are also needed for isolated sites. This paper takes this approach, in which an AC switched reluctance generator is used as a generator with a variable rotor speed. Although the voltage obtained is of insufficient quality to connect the generator directly to the power grid, this kind of generator can be used in isolated sites to charge a battery bank with a simple bridge rectifier. Due to the nonlinear behavior of the machine with the position and current, along with the alternating nature of the current that circulates through its phases, the machine experiences cyclical energy transformations of a mechanical, electrical and magnetic nature. This paper analyzes these transformations for the purpose of providing guidelines for machine design and optimization as a wind turbine in isolated sites. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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5119 KiB

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A Transformerless Medium Voltage Multiphase Motor Drive System

by Dan Wang, Jiawei Yang, Zhu Chen, Chengxiong Mao and Jiming Lu

Energies 2016, 9(5), 323; https://doi.org/10.3390/en9050323 - 27 Apr 2016

Cited by 4 | Viewed by 7354

Abstract

A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV) multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP), a complete improved Phase Disposition Pulse Width Modulation (PD-PWM) method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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1625 KiB

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A New Approach of Modeling an Ultra-Super-Critical Power Plant for Performance Improvement

by Guolian Hou, Yu Yang, Zhuo Jiang, Quan Li and Jianhua Zhang

Energies 2016, 9(5), 310; https://doi.org/10.3390/en9050310 - 26 Apr 2016

Cited by 14 | Viewed by 4887

Abstract

A suitable model of coordinated control system (CCS) with high accuracy and simple structure is essential for the design of advanced controllers which can improve the efficiency of the ultra-super-critical (USC) power plant. Therefore, with the demand of plant performance improvement, an improved T-S fuzzy model identification approach is proposed in this paper. Firstly, the improved entropy cluster algorithm is applied to identify the premise parameters which can automatically determine the cluster numbers and initial cluster centers by introducing the concept of a decision-making constant and threshold. Then, the learning algorithm is used to modify the initial cluster center and a new structure of concluding part is discussed, the incremental data around the cluster center is used to identify the local linear model through a weighted recursive least-square algorithm. Finally, the proposed approach is employed to model the CCS of a 1000 MW USC one-through boiler power plant by using on-site measured data. Simulation results show that the T-S fuzzy model built in this paper is accurate enough to reflect the dynamic performance of CCS and can be treated as a foundation model for the overall optimizing control of the USC power plant. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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3777 KiB

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Feasibility Study of a Scroll Expander for Recycling Low-Pressure Exhaust Gas Energy from a Vehicle Gasoline Engine System

by Xing Luo, Jihong Wang, Christopher Krupke and Hongming Xu

Energies 2016, 9(4), 231; https://doi.org/10.3390/en9040231 - 24 Mar 2016

Cited by 9 | Viewed by 7915

Abstract

The growing number of vehicles on the road has led to a rapid increase in fuel consumption and toxic gas emissions, so the challenges in fuel efficiency improvement and reduction of CO₂ and NO_x emissions have always been on the top agenda of the automotive industry. The paper presents a feasibility study of recovering the low-pressure exhaust gas energy via by-pass connection of a scroll expander to the engine system exhaust. The paper starts with the description of the proposed new exhaust energy recycling scheme and the mathematical modelling of the system. A feasibility study is carried out to investigate whether this new scheme can work with the engine operation conditions specified by the engine test data. The initial study indicated that the scroll expander structure needs to be modified; otherwise, it cannot be used for exhaust energy recovery. The experimental test and simulation results presented in this paper indicate that it is feasible to recover the low-pressure exhaust gas energy using a scroll expander with a modified structure. The proposed energy recovery system has the potential to produce over 400 W power output with over 90% of engine exhaust flow recycling. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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4912 KiB

Open AccessArticle

Application of Breathing Architectural Members to the Natural Ventilation of a Passive Solar House

by Kyung-Soon Park, Sang-Woo Kim and Seong-Hwan Yoon

Energies 2016, 9(3), 214; https://doi.org/10.3390/en9030214 - 17 Mar 2016

Cited by 9 | Viewed by 5803

Abstract

The efficient operation of a passive solar house requires an efficient ventilation system to prevent the loss of energy and provide the required ventilation rates. This paper proposes the use of “breathing architectural members” (BAMs) as passive natural ventilation devices to achieve much improved ventilation and insulation performance compared to mechanical ventilation. Considering the importance of evaluating the ventilation and insulation performances of the members, we also propose numerical models for predicting the heat and air movements afforded by the members. The numerical model was validated by comparison with experimental results. The effectiveness of the BAMs was also verified by installation in houses located in an area with warm climate. For this purpose, chamber experiments were performed using samples of the BAMs, as well as numerical simulations to assess natural ventilation and heat load. The main findings of the study are as follows: (1) the one-dimensional chamber experiments confirmed the validity of the numerical models for predicting the heat and air movements afforded by the BAMs. Comparison of the experimental and calculated values for the temperature of air that flowed into the room from outside revealed a difference of less than 5%; (2) observations of the case studies in which BAMs were installed in the ceilings and exterior walls of Tokyo model houses revealed good annual ventilation and energy-saving effects. When BAMs with an opening area per unit area of A = 0.002 m²/m² were applied to three surfaces, the required ventilation rate was 0.5 ACH (air changes per hour), and this was achieved consistently. Compared to a house with general insulation and conventional mechanical ventilation, heating load was reduced by 15.3%–40.2% depending on the BAM installation points and the differing areas of the house models. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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1814 KiB

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An Efficiency Enhancement Technique for a Wireless Power Transmission System Based on a Multiple Coil Switching Technique

by Vijith Vijayakumaran Nair and Jun Rim Choi

Energies 2016, 9(3), 156; https://doi.org/10.3390/en9030156 - 3 Mar 2016

Cited by 37 | Viewed by 10561

Abstract

For magnetic-coupled resonator wireless power transmission (WPT) systems, higher power transfer efficiency can be achieved over a greater range in comparison to inductive-coupled WPT systems. However, as the distance between the two near-field resonators varies, the coupling between them changes. The change in coupling would in turn vary the power transfer efficiency. Generally, to maintain high efficiency for varying distances, either frequency tuning or impedance matching are employed. Frequency tuning may not limit the tunable frequency within the Industrial Scientific Medical (ISM) band, and the impedance matching network involves bulky systems. Therefore, to maintain higher transfer efficiency over a wide range of distances, we propose a multiple coil switching wireless power transmission system. The proposed system includes several loop coils with different sizes. Based on the variation of the distance between the transmitter and receiver side, the power is switched to one of the loop coils for transmission and reception. The system enables adjustment of the coupling coefficient with selective switching of the coil loops at the source and load end and, thus, aids achieving high power transfer efficiency over a wide range of distances. The proposed technique is analyzed with an equivalent circuit model, and simulations are performed to evaluate the performance. The system is validated through experimental results that indicate for a fixed frequency (13.56 MHz) that the switched loop technique achieves high efficiency over a wider range of distances. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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425 KiB

Open AccessArticle

Diesel-Minimal Combustion Control of a Natural Gas-Diesel Engine

by Florian Zurbriggen, Richard Hutter and Christopher Onder

Energies 2016, 9(1), 58; https://doi.org/10.3390/en9010058 - 19 Jan 2016

Cited by 20 | Viewed by 6211

Abstract

This paper investigates the combustion phasing control of natural gas-diesel engines. In this study, the combustion phasing is influenced by manipulating the start and the duration of the diesel injection. Instead of using both degrees of freedom to control the center of combustion only, we propose a method that simultaneously controls the combustion phasing and minimizes the amount of diesel used. Minimizing the amount of diesel while keeping the center of combustion at a constant value is formulated as an optimization problem with an equality constraint. A combination of feedback control and extremum seeking is used to solve this optimization problem online. The necessity to separate the different time scales is discussed and a structure is proposed that facilitates this separation for this specific example. The proposed method is validated by experiments on a test bench. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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3043 KiB

Open AccessArticle

Optimal Design of an Axial-Flux Permanent-Magnet Middle Motor Integrated in a Cycloidal Reducer for a Pedal Electric Cycle

by Yee-Pien Yang and Jia-Ming Jiang

Energies 2015, 8(12), 14151-14167; https://doi.org/10.3390/en81212421 - 16 Dec 2015

Cited by 9 | Viewed by 21459

Abstract

This paper proposes an optimal design of a middle motor integrated into a mid-drive unit for pedal electric cycles. This middle motor is an axial-flux permanent magnet brushless DC motor with a stator plate. Facing this plate is a rotor plate that acts as an eccentric component of a cycloidal reducer next to the stator. Both the middle motor and cycloidal reducer are easily installed on the same axle of the bike crankset. In the preliminary design, driving requirements are used to make the middle motor specifications. The numbers of stator slots and magnet poles on the rotor were chosen to achieve the best winding factor, and the winding layout was determined accordingly. A one-dimensional magnetic circuit model of the middle motor was built, and its shape was optimized utilizing a multifunctional optimization system tool. Finally, the resulting design was verified and refined by a finite element analysis. A prototype of the middle motor was fabricated with a stator made of a soft magnetic composite and integrated with a cycloidal reducer. Experimental results show that the motor has a sinusoidal back electromotive force. Additionally, it is easily controlled by sinusoidal currents with acceptable torque and speed curves. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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5779 KiB

Open AccessArticle

Electromagnetic Performance Analysis of Novel Flux-Regulatable Permanent Magnet Machines for Wide Constant-Power Speed Range Operation

by Yunchong Wang, Shuangxia Niu and Weinong Fu

Energies 2015, 8(12), 13971-13984; https://doi.org/10.3390/en81212407 - 10 Dec 2015

Cited by 9 | Viewed by 5375

Abstract

Two novel structures of permanent magnet (PM) machine, namely a hybrid excitation flux modulation machine (HEFMM) and a variable flux memory machine (VFMM), which have excellent field-weakening capability, are presented in this paper. The HEFMM incorporates the advantages of parallel hybrid excitation structure and flux modulation structure, so as to increase the torque density as well as increase the constant-power speed range. Inspired by the HEFMM, aiming to further improve the efficiency of machine, the VFMM with aluminum-nickel-cobalt (AlNiCo) PMs in the inner stator which can be magnetized by the current pulse of the direct current (DC) windings is developed. With double-stator structure, flux modulation effect in both machines can be employed to realize the hybrid excitation and regulate the air-gap flux density readily. The operation principle is illustrated and the static and steady performances of the machines are analyzed and compared with time stepping finite element analysis, which validates the effectiveness of the proposed designs. Full article

(This article belongs to the Special Issue Energy Efficient Actuators and Systems)

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