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Hydraulic transient is a flow situation where the velocity of the flow and the pressure change rapidly with time in pipes networks filled with fluid. Water hammer is one of the consequences that may occur accidentally in the reactors cooling system. The pressure level can exceed the limits given by the manufacturer, and it leads to the failure of the pipes integrity or nuclear fuel elements fixation in the core. Cooling system involves many components, and when a flow control component changes abruptly its status (for example, a valve closing or pump trip), it causes rapid changes in velocity and propagates pressure pulses in short time. The cooling system is equipped with flapper valve and flywheel which overcomes the transient issues. A pump or check valve may be stopped or closed abruptly and may cause bad impacts on the system which is simulated with soft trip using flywheel and without flywheel in case of its failure for any accidental reasons. In addition the abrupt valve closure is deemed as a major issue in the system if occurred. AFT Impulse 5.0 software is used to simulate and study the transient of each case. The simulation appears that the reactor cooling system may suffer from surge that may occur during the sudden closure of check valve but in other hand it can be avoided by regular maintenance of flapper valve to open in timely manner.

Recently, researchers have devoted more attention to supercapacitors (SCs) to integrate with batteries in energy storage systems (ESSs) for vehicle applications. In this study, we attempted to characterize the use of SCs in the ESS for a PEM fuel cell vehicle equipped with an alternator to maximize the performance of regenerative braking. We applied lithium-ion batteries (LIBs) and SCs as energy storage devices to examine their effect on ESS. Then we used a hysteresis brake to apply controllable braking force on the flywheel to form hybrid braking (HB) and made efforts to study its behavior to suggest a braking control strategy. We also ran the whole system over the rotational speed to cover the range of driving speed. At last, we sized the SCs for the most commonly used fuel cell electric vehicle (FCEV) in Korea, i.e., Hyundai NEXO, based on the results obtained from the above study by alternator efficiencies.

The practical feasibility and productive viability of a Human-powered flywheel machine (HPFM) system having the capacity to produce 3 to 5 Horse Power (H.P) is preferred over motorized machines for rural-based applications. The present work deals to establish precise dimensionless equations for four parameters i.e. Duration of Energy consumption, Quantity of Material Processed/Time, Quality of shredding parts, Process Horse Power (H.P), and Instantaneous Load Torque using the Buckingham Pi-theorem technique for the waste monomer plastic shredding operation using HPFM. The independent and dependent variables affecting the shredding operation have been identified to form the experimental data-based model equations for the above-mentioned response variables. These equations will further help to understand the phenomenon of shredding plastic using HPFM in the rural sector and they will also help in developing the capacity of the machine according to the various requirements. A distinct experimental plan has been established for calculating the kinetic energy of the system and the different variables identified for the process.

A significant part of an automobile is the gear box (tractor) casing. The primary objective of using the Gearbox casing is to embrace and allow the transmission of the Gearbox. The Gearbox is a mechanism that regulates speed or torque between the flywheel and the differential. The main shaft and lay shaft with gears equipped embraces the gear box. This paper deals with the modeling and study as an alternative material of the gear box casing for a tractor with E-Glass. Through the development of the simulation software platform ANSYS, it is analyzed statically with different design parameters such as web thickness, gear box housing depth and gear box housing thickness. In order to determine the stress produced and deformation degree, the gear box with traditional Grey cast iron is analyzed; it is then compared with the housing of the E-Glass Gear box. The outcome will be studied and evaluated after study, various combinations of design parameters were used to achieve the design that minimum output in failure at higher load s has better deformation characteristics. Finally, in order to design the gear box housing, an optimized design parameter is obtained.[1]

The sharp inclination in the emissions from conventional vehicles contribute to a significant increase in environmental issues, besides the energy crises and low conversion efficiency leads to the evolution of electric vehicles (EV). Hybrid electric vehicles (HEV) have efficient fuel economy and reduce the overall running cost, but the ultimate goal is to shift completely to the pure electric vehicle. Despite this, the main obstruction of HEV is energy storage capability. An EV requires high specific power (W/kg) and high specific energy (W·h/kg) to increase the distance travelled and reduce the time required for charging. The main focus of this paper is on the energy sources as these are the main components in EVs towards making them eco-friendly and cost-effective. Various topologies of EV technology such as HEVs, plug-in HEVs, and many more have been discussed. These topologies of EVs are based on the diverse combination of batteries, fuel cells, super-capacitor, flywheels, regenerative braking systems, which are used as energy sources and energy storage devices.

The present review paper aims to shed lights on the concept of fully green energy system which includes both the source of energy and the storage system. The objective is to propose an energy label “Green to Green” (G2G) that identifies systems involving simultaneously green source and green storage, as an efficient solution to achieve a significant reduction in the dangerous level of pollution that most countries have reached today. Green sources include mainly renewable energy systems such as solar, wind, geothermal and wave energy systems. In its turns green storage includes pumped hydroelectric, flywheel, hydrogen and compressed air. Moreover, and as a case investigation on G2G concept, the paper reviews the main solar-hydrogen coupling systems, that are categorized within four categories parabolic trough-hydrogen, solar tower-hydrogen, photovoltaic-hydrogen and solar chimney-hydrogen.

The CFRP/metal co-cured material which possesses the outstanding properties of both lightweight and high strength has become one of the commonly used materials in the design and manufacture of attitude control flywheel. However, few studies are reported concerning the mechanical drilling operation of this newly developed structural material. To cover the gap and enrich the scientific field of this topic, the present work was performed to specially evaluate the drilling performances of a co-cured material composed of carbon fiber reinforced plastic (CFRP) and invar alloy. The significance of the present work aims to on the one hand, reveal the evolution of vital cutting phenomena including thrust forces, cutting temperatures and surface quality of drilling holes as function of cutting parameters, and on the other hand address the mechanism of controlling the interfacial drilling response. The results indicate that both the thrust forces and cutting temperatures during drilling of the invar phase are relatively higher compared to that of the CFRP phases while it presents elevation for the lower CFRP phase than the upper one due to the effect of chip ejection. The evolution of thrust forces and drilling temperatures present common regularity, in which the feed rate and cutting speed play an essential role, respectively. It is worth noting that the hole size indicates disparities for all the involved layers regardless of the machining parameters, of which the hole size exceeds the nominal diameter for the upper CFRP phase while it presents lower magnitudes for the lower CFRP phase and close gap between the invar phase and expected value. Surface cavity and fiber pullout dominate the hole surface morphology for the upper CFRP phase, matrix degradation and micro-cracks appear on the hole wall of the lower CFRP phase, and chip adhesion and oxidation are the cases for the invar layer. The mechanical effect induces the notch and the thermal effect causes the matrix degradation, which controls the cutting response for the upper and lower interface, respectively.

Several latching control strategies have been proposed to improve the power performance of wave energy converters (WECs). However, the benefits and challenges vary for different WECs and PTO systems. This paper addresses the power performance of a specific direct mechanical-drive power take-off (DMDPTO) system considering the application of a non-predictive latching control. The WEC is a heaving point absorber (PA) that consists of a cylindrical buoy and a bottom-mounted support structure. A pulley converts the vertical motion of the buoy into rotational motion, and a freewheel system rectifies the rotation direction for the power generation. A speed multiplier amplifies the velocity delivered by the buoy to drive a flywheel, which is rigidly connected to the electrical generator. A time-domain model is developed to simulate the interaction of the wave-buoy-DMDPTO in each time interval calculating hydrodynamic and electro-mechanical forces. An exhaustive optimization strategy is applied to maximize power production, optimizing the DMDPTO parameters. The sensitivity of power production to the wave height and wave period are presented considering the generator’s operational limit. Additionally, the capture width ratio and peak-to-average power ratio are calculated for the controlled PA, and the results are compared to the control-free WEC and linear PTO systems.

This paper is devoted to developing a closed-loop vibration suppression controller for a satellite with large flexible appendages based on component synthesis vibration suppression (CSVS) method. The dynamics model of a flexible satellite is firstly established by using the Newton–Euler methodology, and the dynamics model of the flywheel is also developed. A novel CSVS method is presented based on zero-vibration differentiator (ZVD), which can guarantee multi-order vibration suppression. Combined with the proposed CSVS method, traditional closed-loop controllers such as PD or sliding mode controllers can be applied to active vibration suppression. The stability of the proposed closed-loop CSVS controller is proved by the Lyapunov theory. Subsequently, the dynamic optimal control allocation algorithm is proposed for six flywheels, and a novel nonsingular fast terminal sliding mode controller is developed to obtain practical voltage control input for the flywheel drive control system. Finally, numerical simulations are carried out to validate the effectiveness of the proposed method.

The usage of Banana fibers is a best replacement for synthetic materials that are used in the present days. The banana fibers are natural products, bio-degradable and eco-friendly. In India, there are about 5 lakh hectares of banana cultivation areas. The extraction of banana fibers is long time process and also quality of the product varies according to the extraction method. To make the time requirement less and also to improve the quality of the product, the banana fiber extracting machine is designed and fabricated. This machine is a commercial product which can be used by all category people including the rural areas and also by the farmers which will provide an additional income to them. This product is particularly designed for extracting banana fibre from the banana pseudo stem. The machine mechanism is designed in a very modest way which can be used by everyone. The major components used are frame, paddle, bearing, chain, sprocket, flywheel, hard chromed blades with blunt edges roller and shaft.

Inertial mass simulation system is widely used in inertia load simulation of space mechanisms. The error of the inertia mass has a great influence on the mechanism performance test. In this paper, the in-situ measurement technology of flywheel inertial mass is studied: firstly, the theory of in-situ inertial mass measurement is analyzed by use of mass-spring model; secondly, the simulation models of the flywheel before or after attaching counterweights are established based on Sim-Mechanics of MATLAB; at last, according to the simulation test and analysis of the model, the correctness of the theoretical derivation of in-situ measurement is verified, which lays a theoretical foundation for in-situ inertial mass measurement of the flywheel.

The modern world is continuously focusing on a carbon-free atmosphere to improve environmental sustainability. In the last two decades, Human Powered Flywheel Motor has been applied to design numerous rural-based applications. The functional feasibility and economic viability of Pedal-powered process machines of 3 to 5 Horse Power capacity over motorized machines have increased the utility for rural-based applications. The present work deals with the review of various research investigations done on the Human Powered Flywheel Motor system. Further, the conversion of the Human Powered Flywheel Motor into the electromechanical analog circuit and the generation of design data for Human Powered Flywheel Motor through the establishment of generalized experimental data-based models have also been discussed. It is concluded that the Human Powered Flywheel Motor can generate a maximum of 3 to 5 Horse Power, which can be utilized against the various motorized machines in rural applications where intermittent power supply does not affect the end quality of the product.

Variable valve timing (VVT) enables the valve events to vary with RPM for optimum engine performance. It alters the timing on the camshaft using pneumatic, hydraulic or electromechanical means. The Cameless Stepping Valve system uses software controlled valve events. Here, VVT is achieved by advancing/retarding valve events using only the direction of the piston and interpolated virtual angles on the flywheel. The engine model used has an optimum RPM of 24000, which translates to a period of 2.5mS. A 10 angle increment on the flywheel corresponds to 6.9µS. As a result, a retardation/advance of 10 would mean that the valve will open/close 6.9µS after the current/previous TDC. A 9bit real-time digital counter was triggered to count the calculated angles at every Otto Cycle so that advance/retard is updated at every RPM. In this project, it was demonstrated that valve event control is possible using interpolation of virtual angles on the flywheel, replacing a multi-tooth timing wheel. The proposed technique is more accurate and robust.

Motivated by the work of Cai and Hu (2018), this paper considers the dual objective control problem of a flywheel energy storage system targeting simultaneous state-of-energy balancing and reference power tracking. It is first shown that, in the presence of flywheel damping, the steady state solution subject to the dual control objective exists and is defined by a virtual dynamic system. Second, under the identical damping condition, it is proven that the control law proposed in Cai and Hu (2018) can still solve the dual objective control problem.

In this work, a 370-W small wind turbine was developed which is equipped to a controllable nuzzle-diffuser duct. The developed duct is consisting of a fixed ring and a two-piece diffuser which can rotate on each other and so the diffuser wall opening will have altered from 0 to 180°. This mechanism is developed to control speed-up ratio and drag forces acting on the turbine structure in high ranges of wind speeds. The rotor is designed using BEM algorithm and the duct geometry is reached by CFD works considering the atheistic aspect of view. As the turbine is designed for a comprehensive research project, so it contains several a subsystems like an electromagnetic brake, external electric starter motor, electromagnetic flywheel, variable nacelle, etc. The designed mechanism fabricated using several machining processes as turning, milling, boring, drilling, welding and rolling works. The turbine performance implemented in a low-speed wind tunnel. Experimental results show a comprehensive raise in power generation and rotor speed by shrouded wind turbines. In the 180-degree diffuser wall opening, the augmentation ratio in average is 39.75% while the ratio is 28.5% for a complete diffuser augmented wind turbine. The rotor speed-up ratio for them is 53 and 74% respectively.

The alloy steel 42CrMo and the cast Ni-based superalloy K418 were successfully joined by inertia friction welding. The effects of the initial flywheel kinetic energy on the microstructure and mechanical properties of the joints were investigated. The results showed that inertia friction welding is a rapid and efficient way to achieve metallurgical bonding between 42CrMo and K418. Intermetallic compounds Fe0.64Ni0.36, Ni–Fe–Cr, Ni3 (Al, Ti) and MC-type carbides like NbC and TiC were observed at the interface containing a diffusion layer because of element diffusion. Elemental distribution analysis indicated that Fe and Ni were intermixed at the interface. The maximum tensile strength of the dissimilar 42CrMo/K418 joint was 772.19 MPa. Tensile fracture was identified to have occurred on the K418 side with brittle fracture features at an initial flywheel kinetic energy of 50.6 kJ. The origin and expansion of the cracks were mainly attributed to the MC carbides.

In this paper, a novel semi-active variable admittance (VA) concept is proposed, and a seat suspension prototype with a magnetorheological fluid damper based rotary VA device is designed, manufactured, and experimentally validated. The conventional inerter with a single flywheel has a constant inertance, which can effectively improve the suspension performance by being integrated into a mechanical network with springs and dampers. The proposed rotary VA device comprises a gear reducer, two flywheels and a variable damping (VD) device which is used to connect the two flywheels. With carefully designing, the rotary VA device is compacted and is similar with a VD device in size. The rotary VA device is installed in the centre of a seat suspension's scissors structure to form a VA seat suspension. According to the test results, the equivalent inertance of the seat suspension can vary from 11.3 Kg–76.6 Kg with a 3 Hz frequency and 5 mm amplitude sinusoidal movement by changing the current from 0 A–1 A. By analysing the system characteristics, a hybrid controller with two acceleration feedbacks is proposed. Thereafter, the seat suspension and controller are validated in experiments by comparing the performance with a conventional passive seat suspension. The random vibration test shows the excellent performance of the proposed seat suspension; the frequency weighted root mean square acceleration of the seat is reduced by 43.6%, which indicates a great improvement of the ride comfort. The VA device shows great prospect in the suspension application.

Low-cost solar sailing CubeSats for deep-space exploration are relatively inexpensive, have a short development time, and can be launched more often. However, attitude control of a solar sailing CubeSat is challenging due to the low controllability of the CubeSat itself. In this paper, a new attitude control method for the solar sailing CubeSat where solar radiation pressure torque, which is a torque generated by the satellite's center of mass offset with respect to its center of pressure, is used as the controlling torque. In this study, a mechanical structure to adjust the center of mass with the CubeSat as a movable mass is presented. The CubeSat's position on the solar sail's surface plane can be adjusted to control the attitude about the roll and pitch axes. Therefore, a dynamics model for the solar sailing CubeSat is derived and an attitude controller is developed. The method is demonstrated for the case of a 10 × 10 m2 sail with a 12-U CubeSat. The simulation results show that the solar sail attitude maneuver and sun pointing stability control are feasible when the initial and desired states satisfy the constraints. As a semi-active control method, the system can be combined with a micro flywheel control system for the attitude stability control of the CubeSat.

The task of Integrated Power and Attitude Control (IPAC) of a spacecraft can be implemented by Variable Speed Control Moment Gyros (VSCMGs). The Integrated Power and Attitude Control System (IPACS) singularity problem is the key factor for the spacecraft to successfully perform IPAC task, which can be overcome by rational designing steering law. The singularity characteristic and the steering law should be considered during the process of design parameters for the VSCMG cluster with IPACS task. There is no research report in this area at present. The steering results of weighted pseudo-inverse and null motion of Weighted Pseudo-Inverse with Null Motion (WPINM) can be canceled by each other under some certain condition. So the flywheel torque requirement of the WPINM steering law can be greatly increased, which is contradictory to the original design intention of the weighted matrix. A steering law with minimum requirement of flywheel power and torque is introduced from existing research result. Then, the constraint of the IPACS singularity problem and the SGCMGs singularity problem cannot be encountered during the whole process of IPAC task is given. At last, the parameters design problem of VSCMGs for the IPAC task is cast as a multi-objective optimization problem with minimum whole system power and maximum utilization ratio of flywheel momentum under the condition of consideration of the steering. The intelligent algorithm of Non-dominated Sorting Genetic Algorithm (NSGA) is used to solve the nonlinear multi-objective problem. The flywheel power can be greatly reduced by the new parameters design method.

Solar energy is globally promoted as an effective alternative power source to fossil fuels because of its easy accessibility and environmental benefit. Solar photovoltaic applications are promising alternative approaches for power supply to buildings, which dominate energy consumption in most urban areas. To compensate for the fluctuating and unpredictable features of solar photovoltaic power generation, electrical energy storage technologies are introduced to align power generation with the building demand. This paper mainly focuses on hybrid photovoltaic-electrical energy storage systems for power generation and supply of buildings and comprehensively summarizes findings of authorized reports and academic research outputs from literatures. The global installation capacity of hybrid photovoltaic-electrical energy storage systems is firstly examined to show the significant progress in emerging markets. Particularly, the latest installation status of photovoltaic-battery energy storage in the leading markets is highlighted as the most popular hybrid photovoltaic-electrical energy storage technology for building applications. The research progress on photovoltaic integrated electrical energy storage technologies is categorized by mechanical, electrochemical and electric storage types, and then analyzed according to the technical, economic and environmental performances. Moreover, extensive research on hybrid photovoltaic-electrical energy storage systems is analyzed and discussed based on the adopted optimization criteria for improving future applications in buildings. It is indicated that the lithium-ion battery, supercapacitor and flywheel storage technologies show promising prospects in storing photovoltaic energy for power supply to buildings. Potential research topics on the performance analysis and optimization evaluation of hybrid photovoltaic-electrical energy storage systems in buildings are identified in aspects of the local adaption, flexible control, grid integration, as well as building resilience and intelligence. This study provides an insight of the current development, research scope and design optimization of hybrid photovoltaic-electrical energy storage systems for power supply to buildings and can serve as an explicit guide for further research in the related area.

This article deals with the design of a test bench and its dynamic testing. The test bench is composed of a rotor levitated by radial active magnetic bearings and axially by a permanent magnet bearing. The rotor housing is mounted in a passive gimbal and the foundation can translate and rotate to emulate a vehicle accelerating, manoeuvring, and subject to outer perturbations such as waves. The work is motivated by a lack of publically available experimental designs and experimental data for magnetically suspended flywheels on moving foundations. The article will describe the test rig design and subcomponents, present experimental results, and afterwards the test rig will be used to experimentally validate a mathematical model governing the dynamics of the system. It is found that the model successfully captures the dynamics of rotor and housing both in a gimballed and non-gimballed flywheel energy storage system when subject to accelerations of the foundation. The simulated maximum housing accelerations are found to deviate 2% from the experiments while the maximum rotor displacements are found to deviate 37%, but only for rotor displacements larger than 100 μm where the linear approximation to the magnetic forces is no longer accurate.

The present work investigates the advantages of integrating a hybrid energy storage system in a residential micro-grid, coupled to a PV plant. Specifically, battery hybridization with mechanical flywheel is considered. A suitable code, implementing a dedicated logic of power management, is developed to investigate several design conditions and features, simulating the behavior of both storage devices along one year of operation with 1 min time step. The energy performances of the different micro-grid configurations are presented and discussed. Moreover, based on the simulated yearly trends of the battery state of charge, the effects of flywheel on the battery life are determined resulting in a significant improvement with respect to non-hybrid configurations. In particular, life battery almost triples in the case lead-gel technology is adopted, while the life gain reaches a mean value of 3.6 for lithium-ion battery packs. This result is validated through suitable aging tests on LiFePO4 cells over three equivalent years of operation.

A free piston linear alternator (FPLA) can convert the fuel’s chemical energy to electrical energy efficiently via a linear alternator. Since the piston motion in the FPLA is not constrained, there are significant cyclic variabilities in the FPLA’s operation; thus, advanced control methods are essential for prolonged stable operation. In this paper, an FPLA with a high-stiffness helix spring is proposed, called a spring-assisted FPLA. The spring can work as a flywheel to stabilize the engine operation and reduce the cyclic variabilities. The steady-state thermodynamic performance of the engine is studied. Homogeneous charge compression ignition (HCCI) is used for combustion due to its high thermal efficiency and low exhaust emissions. This research is the first focusing on spring-assisted HCCI FPLA with a fully functional system-level model, with accurate predictions of combustion, gas exchange, friction, etc. with each submodel validated. A zero-dimensional system-level model is built in MATLAB/Simulink with a predictive combustion model developed by experimental data on a crank-slider engine. Since the thermodynamics and piston dynamics are highly coupled in FPLAs, a decoupling algorithm called Piston Motion Generator (PMG) is developed to remove the need for controls over the model predictions so that the current study can focus on the thermodynamic performance. A parametric sweep is performed with changing compression ratio, scavenging efficiency, and spring energy ratio β , i.e., spring stiffness. The simulation results show that the free piston motion is distorted with higher acceleration near top dead center (TDC), especially with low energy ratio springs, which can significantly reduce the heat transfer losses. Low energy ratio springs can also delay the ignition timing and enable the use of a low octane rating fuel with high compression ratio to achieve high thermal efficiency. As a result, the maximum brake efficiency (electrical conversion efficiency) and thermal efficiency are 41.1% and 46.7%, respectively, achieved with a high compression ratio, high scavenging efficiency, and low spring energy ratio β .

A magnetically suspended flywheel (MSFW) always suffers from rotor mass imbalance disturbances, which result in synchronous vibration forces and affect the high precision control. The synchronous vibration forces in MSFW are mainly comprised of current stiffness forces and displacement stiffness forces. In this paper, a lead feedforward compensation method is proposed to simultaneously suppress the two stiffness forces. First, the dynamical model of the synchronous vibration forces and the phase lag influence of the power amplifier on the displacement stiffness forces are given. Then, the principle and implementation of the proposed method used for synchronous vibration forces complete suppression are analyzed. The performance comparison between the conventional scale compensation method and the proposed lead feedforward method is investigated. Simulation and experimental results on a MSFW demonstrate the effectiveness and superiority of the proposed synchronous vibration forces suppression method.

This paper presents the theoretical development and performance of novel Input–Output Linearization (IOL) AC voltage controllers applied to Dynamic Voltage Restorers (DVR) with Flywheel Energy Storage (FES). IOL performance is compared to decoupled proportional integral (PI) controllers, both relying on a backward Euler predictive current controlled AC–AC matrix converter. The critical load AC decoupled voltage control using IOL or PI is detailed as well as the backward Euler predictive current control. The matrix input and output current tracking control uses a backward Euler predictive current control minimizing a weighted cost functional. The stable backward Euler matrix vector estimation enables the AC–AC matrix to perform as a current tracking converter. Experimental results are obtained using a laboratory level DVR fitted with FES device made from a vertical axis rotating seamless steel hollow cylinder (flywheel) storing kinetic energy. The flywheel is coupled to a Permanent Magnet Synchronous Machine (PMSM) motor/generator, which is driven by the AC–AC matrix converter. The DVR was tested to mitigate voltage sags in isolated neutral critical loads, using IOL and PI controllers. The DVR is able to compensate the critical load voltage without noticeable delays, voltage undershoots or overshoots, overcoming the input/output coupling problem of matrix converters. IOL controller proves to be faster and more aggressive than the PI controller, which is softer introducing less voltage distortion.

In this work, we analyze the application potential of adequate FRPs for the storage and handling of mechanical energy and power. We demonstrate that the elastic deformation of certain FRPs in adequate shapes can give rise to energy storage and power handling systems with similar or even better technical and economic performance as other systems as flywheels and supercapacitors in terms of energy, power density and cost per cycle. The concept leads to additional advantages as robustness, simplicity, long service life, high depth of discharge and low self-discharge. Fiber reinforcements as high strength carbon, glass, aramid or PBO, with high specific strength and low specific stiffness, are analyzed in terms of energy, power density and cost, showing some of them an interesting applicability potential. Finally, the hypothesis is demonstrated by the operation of two prototypes based on glass and carbon fiber-epoxy spiral springs.

In recent years, application of energy storage technologies in smart grids has attracted huge attention. In this paper a cost-benefit analysis is carried out to evaluate and quantify the benefit of installing an energy storage system (ESS) in a typical Microgrid (MG). The model aims to yield the optimal ESS size by finding the least cost energy scheduling over a year under an uncertain environment. Therefore, a two-stage stochastic programming (SP) is defined to address the probabilistic nature of the parameters. The moment matching method is incorporated to create samples form probability distribution functions (PDFs) as nodes of a scenario tree. Furthermore, the fast forward selection (FFS) approach is utilized for scenario reduction. Lead acid battery (LAB), flywheel (FW) and pumped hydro energy storage (PHES) are chosen as ESS candidates. Simulation results demonstrate that whether operating as islanded or grid-connected, favorable yearly cost savings are achieved by optimal ESS planning. In this regard, the scheduled load responses and signed bilateral contracts (BCs) play important roles. The effectiveness of the proposed approaches is verified through comparisons with the deterministic and common stochastic methods. Finally, a sensitivity analysis is carried out on ESS cost to examine its effect on optimal sizing.

Because of the launch vibration and shock, magnetically suspended flywheels (MSFWs) are equipped with an additional launch locking protective device (LLPD), and the LLPD performance has great influence on the attitude control precision of the flywheel system. In this paper, a LLPD that takes the carbon fiber bracket as the key clamped and releasable mechanism was presented. And the configuration, operating principle and functional performance requirements were introduced. The locking/unlocking force, maximum stress and contact force of the carbon fiber bracket were analyzed. The dynamic analysis of the single carbon fiber bracket equivalent to the cantilever beam model was carried out. Subsequently, the sensitivity of the constraint variables vs the structural parameters was calculated. The lower and upper parts of the carbon fiber bracket were separately optimized. The result shows that the mass of the carbon fiber bracket can reach to the minimum of 60.5 g when the number of the upper carbon fiber bracket slices is 12. Finally, the LLPD prototype was manufactured and its locking protection for the flywheel system was verified by the swept-sine vibration and the random vibration.

Control moment gyros (CMG) have been widely used in spacecraft attitude control and large angle slewing maneuvers over the years. Understanding and suppressing high-frequency disturbances in CMG’s output torques is a crucial factor to achieving the desired level of payload performance. Output torque modeling of a single gimbal CMG (SGCMG) with nonlinear rolling bearing supports is conducted in this paper. Taking the installation errors and micro-vibrations of the flywheel into account, three axis output torques of a SGCMG are derived based on Newton-Euler approach and theorem of moment of momentum. Dynamic model is then constructed to obtain the micro-vibration responses of the rotary flywheel. Mass imbalances of the flywheel, flexibility of supporting structures and nonlinearity induced by one pair of angular contact ball bearings are considered in the dynamic model. Especially for the rolling bearing, an improved load distribution analysis is proposed to more accurately obtain the contact deformations and angles between the rolling balls and raceways. Various factors, including the preload condition, surface waviness, Hertz contact and elastohydrodynamic lubrication, are included in the analysis. The bearing restoring forces are then obtained through iteratively solving the load distribution equations at every time step. Dynamic tests on a typical SGCMG supported by angular contact ball bearings are conducted to verify the output torque model. The effects of flywheel dynamic/static eccentricities, inner/outer surface waviness amplitudes, bearing axial preload and installation skew angles on the dynamic output torques are discussed. The obtained results would be useful for the optimal design and vibration control of the SGCMG system.

Flywheels are one of the promising energy storage devices for stabilizing the power quality of reusable energy, owing to their fast response time and high cycle lifetime. However, it can be catastrophic when they fail, because they store kinetic energy that can be released in a short amount of time. Data-driven monitoring techniques have been proposed to solve fault detection tasks in several types of rotation machinery with ball bearings. In contrast to traditional approaches using human-engineered features that require a high level of expertise, a data-driven approach requires no such prior knowledge. However, flywheels differ from typical rotation machinery because they use a magnetic or pivot bearing, and it is unclear whether a data-driven method can be used to detect a fault. In the present study, the effectiveness of a data-driven fault detection system for flywheels that use pivot bearings is evaluated. A flywheel fault progresses in several stages, and vibration data were collected for a flywheel running at each of those stages. A convolutional neural network (CNN) was exploited to detect a fault of the flywheel and identify a mode of the fault. Experimental comparisons conducted using vibration signals from an actual flywheel demonstrated that faulty operational state observed at an end of the flywheel’s life can be detected with high accuracy using a data-driven method.

Quality of the casting is affected by various factors which the designer need to take during the development process of the product. The residual stress is often not examined in applied computations, so residual stresses are the unremembered part in designing of the machine parts. The work is focused on experimental inspection of residual stresses in a high pressured die casted fly wheel, with the aim of increase its efficacy, by taking results as a feedback. In inspecting the residual stresses in the component, one method is adopted that is physical measurement method. The physical measurements were carried out in the Hole Drilling Method. The values obtained from this study show the results with small deviations are seen, which shows the hole drilling methods reliability when stress levels are less. It is also initiated that the compressive residual stresses influence in the component with respect to residual stresses.

The article deals with the issue of a test facility for the experimental research of the friction properties of the brake systems of rolling stock. The article presents the individual parts of the UIC flywheel brake test bench and the possibility of measuring the individual quantities according to UIC requirements. The article presents a calculation of the normal and tangential force generated by braking of the brake disc. The main goal is the calibration of the tangential force sensor and the detection of the possible hysteresis of the braking system, the determination of the characteristics and linearity of the tangential force sensor and results measured by flywheel brake test bench must be relevant and usable for further scientific research into the brake systems of rolling stock.

Flywheel energy storage systems (FESSs) store kinetic energy in the form of Jω2⁄2, where J is the moment of inertia and ω is the angular frequency. Although conventional FESSs vary ω to charge and discharge the stored energy, in this study a fixed-speed FESS, in which J is changed actively while maintaining ω, was demonstrated. A fixed-speed FESS has the advantage of being capable of direct grid-connection without requiring a power electronic interface. A prototype with an output power of several hundred watts and a charge/discharge period of several seconds has been developed and discharge/charge operations have been conducted while mechanically measuring the output energy E m from the flywheel and mechanical work E c , to vary J. Theoretical analysis suggests a ratio of 2.2 for E m / E c , and experimental values of E m / E c show high reproducibility, approximately 1.8 and 2.7 in discharge and charge operations, respectively. The reason for the errors can be explained by the loss incurred in varying J.

The microvibrations that affect the output performance of control moment gyroscopes (CMGs) are important in spacecraft attitude control systems. To reduce the influence of vibrations, researchers have done much work to isolate the vibrations between the CMG and the satellite. However, the deformation of the flexibility isolator affects the direction of the angular momentum, which affects the dynamic performance of the CMG inverse. In this research, using the Lagrange’s equation, the dynamic model of the CMG-isolator coupling system with the exciting force of the dynamic unbalance torque, the CMG’s gyro torque and the gimbal motor torque is developed. Based on this model, the coupling relationship between the gimbal rotation and the isolator deformation is established. For this CMG-isolator coupling system, we conduct the simulations to study the influence of the flywheel speed and the isolator stiffness on the CMG’s output performance and its gimbal’s rotation. Finally, the experiments on a CMG prototype are conducted, which verify the dynamic model and the simulation results of the CMG-isolator coupling system.

Flywheel energy storage system (FESS) is an energy conversion device designed for energy transmission between mechanical energy and electrical energy. There are high requirements on the power capacity, the charging efficiency and the output precision of FESS. Active magnetic bearings are used to suspend the flywheel (FW) rotor of the FESS in air to eliminate friction. A high rotating speed of the flywheel can increase the power capacity but it also increases the disturbance load torque on the FW rotor. An observation control model of load torque is therefore proposed to mitigate the disturbance load torque acting on magnetically suspended FESS (MS-FESS) during the charging process. Moreover, for the discharging process of MS-FESS, a compound control model combing the sliding model control and the extend state observer is proposed to improve the response speed and the output voltage precision. Simulations and experiments are conducted to testify the control performances of proposed control models during the charging and discharging processes of a MS-FESS. The charging efficiency is improved by 17.6% with 46.6% reduction of the output voltage error after using the proposed control models for the charging and discharging process control. The proposed control method has high potential to be applied for process control of charging and discharging of practical MS-FESS.

This study investigates the dynamic force transmissibility (DFT) of angular contact ball bearings (ACBB) supported flywheel rotor systems (FRS) considering the clearance fit. By introducing the influences of combined load and contact angle variation in the Jones formula, the internal load distribution and nonlinear stiffness of ACBBs are accurately solved. The rigid inner/outer ring contact model is adopted to characterize the clearance fit between the ACBB outer ring and mounting sleeve. Based on the Hertzian contact theory, the discontinuous and nonlinear support stiffness caused by the clearance fit is obtained analytically. The lateral vibration model of the FRS considering the fit clearance and ACBB nonlinear support stiffness is established. Combined with the harmonic balance method and alternative time/frequency technique, the DFT of the system is determined, and the stability of the results is proved. Numerical integration and dynamic tests are used to verify the accuracy of the analytical model and solution method. Based on these, the effects of unbalanced mass, fit clearance, axial preload, and rotor damping on the DFT are discussed. The support stiffness of the FRS is nonlinear after considering the ACBB and fit clearance. The amplitude of the unbalanced mass determines the nonlinear characteristics of the system. Increasing the fit clearance decreases the speed corresponding to the peak of the DFT curve. The resonant peak of the DFT curve shifts to the high-speed region with an increase in axial preload. In addition to increasing the peak value of the DFT curve, reducing the damping coefficient causes a soft-to-stiff alternation phenomenon in the system DFT curve. The results provide an important reference for designing a reasonable vibration isolation system to reduce the transmission of micro vibrations of the FRS to a spacecraft platform.

As an external combustion engine, the Stirling engine has low noise and can also easily use renewable and modern energies, such as solar energy. In this study, the dynamic synthesis of the alpha-type Stirling engine will be discussed. By combining the Stirling engine's thermodynamic and dynamic models, it is possible to predict the thermal efficiency, output power, and output velocity of the engine. It can be seen that the output angular velocity of the engine has some undesirable fluctuations. The main goal here is to reduce or eliminate the oscillatory behavior of the output angular velocity by optimizing the links' lengths and their mass distribution in the engine's mechanism. Three optimization methods, namely the Genetic algorithm, the Particle swarm optimization, and the Imperialist competition algorithm, are used for searching the optimum design based on minimizing the output velocity fluctuations. Results show that if the flywheel's mass moment of inertia is fixed, the angular velocity fluctuations have decreased by 24.18 %, 19.20 %, and 24.48 % using GA, PSO, ICA, respectively. Moreover, at the same time, the efficiency has been improved by 38 % approximately. For the best design in this case, which was extracted from Imperialist competition algorithm, the fluctuation has reduced to 133.72 rpm, while the average output velocity is 2620 rpm. Furthermore, as a second case, increasing the flywheel's mass moment of inertia directly affects reducing the velocity fluctuations.

Flywheel energy storage system is widely used in train braking energy recovery, and has achieved excellent energy-saving effect. As a key component of the flywheel energy storage system, the health of the bearing is greatly significant to realize the effective recovery of train braking energy. The vibration signal of the bearing presents complex nonlinear and non-stationary characteristics, which makes it difficult to diagnose the fault of the bearing. To solve this problem, a fault diagnosis method for bearing of flywheel energy storage system based on parameter optimization Variational Mode Decomposition (VMD) energy entropy is proposed. Firstly, the improved Sparrow Search Algorithm is used to optimize VMD parameters with the dispersion entropy as the fitness value. Then, the original signal is decomposed into a series of intrinsic mode components by using the optimized VMD algorithm, and the energy entropy of each component is calculated to construct the feature vector. Finally, an Inverted Residual Convolutional Neural Network (IRCNN) is used as feature vector input model for fault diagnosis. The experimental results show that the proposed method can effectively extract the bearing fault characteristics and realize accurate fault diagnosis, and the recognition rate reaches 97.5%, which is better than the comparison method.

This research deals with an optimization of a dual mass flywheel (DMF) with centrifugal pendulum vibration absorbers (CPVAs) used in a single-shaft parallel hybrid electric vehicle (HEV) powertrain for the reduction of the torsional vibration at the rotor of the electric motor and the total moment of inertia of the DMF and CPVAs. Unlike the previous studies, this research considers the overall behavior of an entire powertrain with an in-line four-cylinder engine and a five-speed automatic transmission for the optimization of the DMF with CPVAs. For this purpose, the multibody dynamics model of the HEV powertrain is constructed and used to analyze the transient response of the system for a given gas pressure map and acceleration condition of the vehicle. Then, a multi-objective genetic algorithm is applied to determine the Pareto optimal front that yields the design parameter values of the DMF and CPVAs effective in the torsional vibration reduction and inertia minimization. The result of the optimization is compared with the HEV powertrain system with a flywheel only, and shows that the vibrations transmitted to the motor are significantly reduced in all the solutions of the Pareto front. By using the method proposed in this research, various parameter combinations of the DMF and CPVAs can be considered in the early design process.

This paper presents design, optimization, and analysis of a flywheel energy storage system (FESS) used as a Dynamic Voltage Restorer (DVR). The first purpose of the study was to design a flywheel with a natural resonance frequency outside the operating frequency range of the FESS. The second purpose of the study was to show that a matrix converter structure can be used for a FESS. The matrix converter can bidirectionally convert the power between the grid and the flywheel due to its natural property. The matrix converter needs a special motor/generator design, because of the voltage utilization ratio of the matrix converter. Therefore, a Permanent Magnet Synchronous Motor (PMSM) being compatible with the matrix converter voltage level was designed and optimized as the third purpose of this study. The motor was optimized to achieve low torque ripple and as high torque as possible by using multi-objective optimization algorithm. Input/output voltages of the FESS are analyzed for grid interruption and 50% voltage sag operation conditions. The frequency analysis study was performed by using SolidWorks, the PMSM was designed and optimized by using MAGNET-Infolytica, and all the other results are performed by using MATLAB-Simscape.

A nonlinear centrifugal pendulum vibration absorber (CPVA) with normal-force dependant friction loss is investigated in a torsional model of a downspeeded powertrain of a heavy-truck. The engine model includes gas-pressure excitation and the existing pendulum model is extended to include a continuous formulation of end-stops at the end of the pendulum-path. Furthermore, the friction loss of the pendulum is experimentally determined. A pendulum-path parameter-study in the complete powertrain model is conducted to consider the effects of the system dynamics on the CPVA. It is shown that the performance of the CPVA is affected by the powertrain system-dynamics and thus important to consider in the design of the CPVA. Downspeeding of the engine by appropriate gearing of the driveline is a measure to decrease the CO 2 emissions. However, downspeeding increases the torsional vibration and noise of the powertrain with conventional torsional vibration reduction methods. The CPVA can be used to reduce the torsional vibration and thus facilitate to reach environmental goals.

The main challenge in today’s power grid management is the inclusion of renewable energy sources with inconstant energy production such as wind and solar plants and modern high technology fabrication or electric transportation with their uneven power consumption. For that purpose energy storage systems, such as high efficiency flywheels, with extraordinary cycle stability and charging-discharging rates are needed. Here carbon fibre reinforced composites play an important role as rotor material. In this study the cracking behaviour of helical layers of a cylindrical flywheel rotor is analysed under consideration of fabrication induced residual stresses and their viscoelastic reduction over long term storage. Based on static and fatigue experiments with crack counting inspections a finite fracture model is identified and calibrated for modelling the damage behaviour of flywheel rotors under cyclic loading.

Energy harvesting from the shock absorbers is now becoming an important technology in developing the electrical vehicles. Compared with other kinetic energy sources such as engine and brake systems which are continuous or periodic, the shock absorber is subjected to the fluctuated linear motion with relatively small displacement. This paper presents a novel indirect-drive regenerative shock absorber system that utilizes an arm-teeth mechanism to achieve linear to rotary motion conversion and to amplify its input speed for increasing energy harvesting output. The fluctuation of road randomness can be smoothed out through the flywheel. The proposed design has the advance of achieving all the targets with less number of components. Two prototypes of the direct-drive and indirect-drive regenerative shock absorbers have been built. The simulation models have been developed and validated by experimental results. The performance of this new indirect-drive system has been compared, through experimental testing and analytical modeling, with that of a conventional direct-drive system of the same generator configuration. The results show that this indirect-drive system can achieve greater peak power output and broader frequency bandwidth than the conventional direct-drive system. The indirect-drive system also presents a better ride comfort up to 13 Hz. Using Monte Carlo simulation, a parameter sensitivity analysis of both the indirect-drive and direct-drive systems has been carried out to compare their energy harvesting performances in terms of increasing the peak power output and broadening the energy harvesting frequency bandwidth. In both the systems, choosing the right tyre stiffness and electromechanical coupling constant is beneficial to increasing the peak power output ratio and the harvesting frequency bandwidth. The right choice of the gear ratio can further improve the peak power output ratio of the indirect-drive system. The variation of these parameters will allow for possibility of achieving higher power output when vehicle is driven on random road surfaces.

Most recent research on flywheel rotors has focused on high-speed composite rotors as the storage element of the flywheel energy storage system (FESS). Literature research indicates that this is primarily due to the high specific energy of composites compared to metals. However, a quantitative comparison of the performance of flywheels made from these materials has not been conducted. This paper aims to answer the question - ‘Are composite flywheels better suited for energy storage than metal flywheels?’. This study uses three different performance indices: kinetic energy; specific energy; and, energy per cost, to compare the corresponding rotor designs. A plain-stress, linear elastic mathematical model of the flywheel rotor described by Krack et al. (2010) is used for analysis. Different optimization formulations corresponding to performance indices chosen based on the FESS application are then solved to study optimal FESS designs. The study indicates that for applications where the energy-per-cost is to be maximized, metals are superior to composite rotor materials. On a total energy basis, metals and composites are on par with each other. Composite rotors are however, superior for applications requiring high specific energy. A hybrid rotor, with a metallic energy storage element and a thin composite burst-rim, is also optimally designed and found to be a viable solution, because it offers the cost benefit of metal rotors, as well as the burst-safety provided by composites. Keywords: Flywheel energy storage, Optimization, Rotor materials, Kinetic energy, Specific energy, Energy per cost

Flywheel energy storage systems (FESSs) with active and passive magnetic bearings are generating interest due to their increasing energy-storing potential caused by advances in motor, bearing and fibre-composite technology. Magnetically suspended FESS are used commercially on static foundations while vehicle applications pose challenges due to manoeuvring, impacts, and other outer perturbations and have thus only seen successful experimental application in a few research projects where the FESS has been mounted in a passive gimbal to avoid gyroscopic forces. Although experimentally implemented, a mathematical model is still missing that determines motions and forces when the FESS is suspended in magnetic bearings, gimbal-mounted, and subject to outer perturbations. This work thoroughly describes how to set up a mathematical model that couples the multi-body dynamics of a flywheel rotor, housing, and gimbal-mount with the magnetic forces of the bearings. The model is used to simulate the behaviour of a FESS with and without gimbal and subject to various perturbations. The results demonstrate how the gimbal mount effectively removes gyroscopic forces but introduces other potential challenges such as large rotor and housing displacements due to dynamical interactions between the rotor, active magnetic bearings, housing, and gimbal.

Because one-shot launch locking/unlocking device (OSLLUD) cannot repeat locking/unlocking, and repeatable launch locking/unlocking device (RLLUD) has an insufficient reliability of implementing unlocking, a novel RLLUD consisting of a motor, wire rope and several same flexible brackets was proposed. The composition, operating principle and functional performance requirements were introduced. A single flexible bracket was equivalent to a cantilever beam-mass model, and its static and dynamic performances were analyzed. Design variables were selected according to the sensitivity analysis method. Unlocking force, the maximum stress and the first resonance frequency were concerned, and the flexible brackets were optimized through the comparison and the sequential quadratic programming methods. The RLLUD was manufactured according to the optimization results. The environmental mechanics tests of tri-axial swept-sine and random vibration were carried out to verify the protective effect of the novel RLLUD for magnetically suspended momentum flywheel (MSMFW) during launch. The results show that the maximum macroscopic vibration is less than the protection gap of the flywheel, and its locking protective effect is valid and sufficient.

Three Dimensional Magnetically Suspended Wheel (3-DMSW) is a new kind of inertia actuator for spacecraft attitude control, which can provide a 3 degrees of freedom torque. On account of the constraint characteristics of 3-DMSW such as a small deflection saturation angle of rotor shaft and the saturation of rotor's variable rotational speed, an anti-saturation steering law based on weighted pseudo inverse is proposed for 3-DMSW cluster. A new weight adjustment method is proposed to adjust the weights of shaft deflections dynamically. A specially designed exponential function with current deflection angle and angular velocity information on the exponent position is adopted as the evaluation criterion of current torque output ability of shaft deflection. Thus the torque command can be distributed dynamically with no angle saturation. The weight adjustment method is demonstrated theoretically and the effectiveness of the anti-saturation steering law is validated by conducting several numerical simulations of attitude agile maneuver. Comparing with the 3-DMSW cluster and flywheel cluster using the traditional steering law, the results show that the 3-DMSW cluster using the proposed method makes the process of agile maneuver more rapid and accurate and the saturation angles of 3-DMSW cluster will not be reached.

A truck engine crankshaft fractured during the service. The fracture occurred on the crankshaft big-end on which the timing-gear and the flywheel flange were coupled and the fracture location was just situated at the assembling gap between them. The short cracks inclined at about 45° to the shaft axis initiated from the surface of the crankshaft journal at the timing-gear side and mainly extended to the timing-gear side, leading to a zigzag cracking morphology on the journal surface. A complicated ratchet or star-shaped pattern of fracture typical of multiple fatigue cracks occurred on the fracture surface. The journal surface was locally induction-hardened. The surface hardness and the effective case depth on the hardened journal at the flywheel flange side corresponded to the specification. At the timing-gear side the surface hardness on the hardened journal was much lower than the specified lower limit and a low hardness region of 0.4 mm occurred on the most-surface of the hardened journal within which the hardness values were lower than the specified lower limit. The low surface hardness on the induction-hardened journal made fatigue resistance of the crankshaft decrease to lead to initiation and propagation of fatigue cracks in the weaker region. The assembling gap at which the fracture occurred was structure stress concentration site of the assembly constituted of the crankshaft, the timing-gear and the flywheel flange, equivalent to the deep notch. The excessive tightening of the timing-gear on the journal surface also contributed for the increasing of stress concentration. The fatigue crack origins were easy to initiate due to large stress concentration.