Search

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.

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]

Synchronous vibration and gyroscopic effect are the key factors affecting the global stability of flywheel batteries in the full speed region. The existing control methods generally treat them as two separate problems; however, they have something in common that can be exploited. In this article, a novel stability control method based on golden frequency section point is proposed for gyroscopic effect and synchronous vibration. The golden frequency section point is the bifurcation point of the nutation and precession of gyroscopic effect, and it is also the switching point of the control method with synchronous vibration at low and high speed. A case study of the centripetal force magnetic bearing-rotor (CFT-MB-R) system is taken as an example to verify it. First, the dynamic model of magnetic bearing rotor system is established. Then, the golden frequency section point is designed, and on this basis, the stability in the low-speed region and the high speed region are analyzed, respectively. Finally, simulations show that the vibration amplitude is reduced by nearly 50% at low speed and 66.6% at high speed. Moreover, the vehicle condition simulation results show the robustness of the system can also be improved. The experimental results further indicate that the method is an effective in suppressing the synchronous vibration and gyroscopic effect of the rotor system, and the stability and even robustness of the system can be greatly improved.

This paper presents methods of increasing the energy storage density of flywheel with superconducting magnetic bearing. The working principle of the flywheel energy storage system based on the superconducting magnetic bearing is studied. The circumferential and radial stresses of composite flywheel rotor at high velocity are analyzed. The optimization methods of the thickness distribution of the flywheel rim and the material selection of the flywheel in the multi-layer interference assembly with a certain size are given and used to maximize the energy storage density. Finally, the improved flywheel model is established, and the maximum energy storage density of the flywheel is increased by combining the above methods.

Conventional suspension forces modeling methods are usually only focused on the computation of the internal magnetic field of the magnetic bearing itself. However, the modeling accuracy is also affected by its actual application, especially for the magnetic bearing in moving situation, such as magnetic suspended flywheel battery system for electric vehicles. In this article, taking the centripetal force type-magnetic bearing as an example, a dynamic correction model considering influence of foundation motions is proposed, which has several submodels to cover as many driving conditions as possible. First, a universal static model based on spherical coordinate system is established. Then, the dynamic model is derived, which includes the control current, offset, and variables of foundation. Given the complexity and diversity of real-time operating conditions of vehicles will affect the calculation accuracy of variables of foundation, resulting in the increase of the error in single dynamic model. Therefore, the idea of foundational weight factor is brought up and fitted by analyzing the dynamic response laws of rotor under different foundation motions. Finally, the dynamic stiffness experiments and performance tests are carried out. The good experiment results show that the proposed model is more practical and has higher precision than traditional model.

This article proposes a topology of special axial split phase (ASP) bearingless switched reluctance (BSR) machine for flywheel applications named ASP-bearingless flywheel (ASP-BF) machine, which adopts hybrid-inner-stator permanent magnet (PM) structure and exhibits complete decoupling of torque and radial suspension force, four degrees-of-freedom (DOF) actively controlled suspension, high torque and radial force density. The topologies of conventional radial split phase (RSP)-BSR machines and the proposed ASP-BF machine are comparatively investigated. It is found that problems of conventional RSP-BSR machines, i.e., the radial suspension force generation dead zone and strong coupling of radial suspension force and torque, can be solved in ASP-BF machines and the suspension DOF can be doubled. Electromagnetic performances, including magnetic field distribution, inductance, torque, radial force are comprehensively investigated. Further, the concept of degree-of-coupling (DOC) is introduced, and the DOCs of the proposed machine and conventional machines are quantitatively analyzed and compared. It shows that the DOC of ASP-BF machine in two cases are 3.41% and 4.05%, less than a quarter of the conventional 8/10 pole machine (22% and 16%) and less than half of the 12/14 pole machine (8.57% and 11.3%). Finally, a 3 kW/100 Wh prototype is built and the experiments proved the validity.

Optimization of kinematic and power characteristics of the drive of the executive body of the machine unit is solved in various ways, among which the most common is the use of additional flywheels, which causes an increase in the weight of the mechanism. The optimal solution to the corresponding contradiction is a method of selecting such a standard gearbox, the swing torque of which would correspond to the additional flywheel. But in practice it is almost impossible to choose a suitable gearbox, so it is better to design new ones, the moments of inertia of the rotating masses of which could perform the function of a flywheel, with mandatory conditions for the uniformity of mechanical gears. The tasks of designing step gears are many criteria, as there is a need to take into account the parameters that are interdependent. In this case, on the one hand, it is necessary to select the appropriate mass of mechanical transmission units that would act as a flywheel, and on the other hand, the gear stage must meet the condition of uniformity, which will ensure uniform durability and reliability of the respective transmission elements. This approach is the most cost-effective, as it significantly reduces the cost of manufacturing and especially maintenance of the respective gearboxes. This paper considers the problem of designing step gears which must satisfy the condition of uniformity, which will ensure their uniform durability and level of reliability. Based on the dependences obtained from the mathematical model of a two-speed gearbox, the problem of designing step gears, the stages of which satisfy the condition of uniformity, is solved. According to the obtained results, it can be stated that the introduced ratio of gear ratios of the gearbox allows at the preliminary design stage to select gear ratios for the respective gearbox gears in such a way as to provide a condition for optimizing step gears by strength criteria.

Homopolar inductor machine (HIM) has been applied in the field of flywheel energy storage system (FESS) due to its merits of simple structure, brushless exciting, and low idling losses. The rotor of HIM not only plays the role of energy conversion but also serves as a flywheel to store kinetic energy, which is different from other electrical machines used in FESS. Meanwhile, the HIM usually operates at high speed to improve the power density and storage energy. To obtain good performance and high reliability, the design and optimization of HIM should consider multiphysics, including storage energy, electromagnetic performance, rotor stress and dynamics, and so on. However, the existing researches mainly focus on the analysis of electromagnetic performance and lack multidisciplinary design. To solve this problem, a multidisciplinary design method of HIM is proposed and investigated. First, the operation principle of HIM is illustrated, and the multidisciplinary design method is proposed. Then, the storage energy, electromagnetic performance (including no-load air-gap flux density, saliency ratio, torque, and electromagnetic power), rotor stress, and modal of HIM are deeply analyzed according to the proposed design flow. Finally, a prototype of HIM is manufactured and tested. The results calculated by finite-element analysis are validated by experiments. The design method proposed in this article provides a straightforward procedure for the multidisciplinary design of HIM.

Due to the low radial restoring force stiffness of the radial high-Tc superconducting maglev bearing (SMB) in high-Tc superconducting flywheel energy storage system (SFESS), it is difficult to provide enough radial constraint when the rotation speed is high. The dynamic simulation analysis of the SFESS rotor was carried out based on the testing and analysis of the static force results of the SMB. On the one hand, according to the results of dynamic analysis, the flywheel rotor would be eccentric when it is subjected to an unbalanced force. On the other hand, because of the special operation mechanism of the SFESS, the flywheel rotor would be prone to be eccentric before rotation. These two types of eccentricity will affect the operating performance of SFESS. Therefore, the research on the working condition of SFESS under eccentric state not only can predict the operating performance of SFESS in extreme cases in advance but also judge whether the SFESS has eccentric operation by comparing the real-time speed value with the preset value, which is of great significance to the further research of the SFESS.

Based on the principle of Lagrange mechanics, especially considering the effects of rotation damping and nonsynchronous damping, a radial 4-dimensional dynamic model of the flywheel bearing rotor system is proposed. Applying the Laplace eigenvalue method, the stability effects of rotational damping, nonsynchronous damping, and their coupling effects are investigated by means of root locus method. Under the control of the linear quadratic regulator, dynamical characteristics of the flywheel bearing rotor system with varied rotational damping and nonsynchronous damping are also studied. The results show that the rotation damping, nonsynchronous damping, and their coupling effects have vast and complex instability effects on high-speed flywheel bearing rotor system. However, there are three exceptions. The tiny proportional rotational damping, remaining below 12%, and the minuscule proportional co-nonsynchronous damping; the product of the nonsynchronous damping and the speed ratio below 5% both can enhance the stability of the system. Furthermore, in the situation that the counter-nonsynchronous damping is coupled with the large proportion of rotational damping, the stability of the system can also be boosted distinctly. On the other hand, the numerical experimental results show that the rotational damping and nonsynchronous damping have a beneficial effect on the flywheel system controlled by linear quadratic regulator. In addition, under the control of linear quadratic regulator, the transient dynamical behavior of the flywheel rotor system with rotational damping or co-nonsynchronous damping performed better than the flywheel rotor system with the coupled damping. The numerical simulations of the transient response of the flywheel rotor system under active control are consistent with some of the derived stability analysis results. The results about the stability analysis and the performance in vibration control give the suggestions for the instability control and fault detection of the system.

Flywheel energy storage systems (FESS) are devices that are used in short duration grid-scale energy storage applications such as frequency regulation and fault protection. The energy storage component of the FESS is a flywheel rotor, which can store mechanical energy as the inertia of a rotating disk. This article explores the interdependence of key rotor design parameters, i.e., shape, operating speed, rotor radius, standby losses, and choice of material, and their influence on the energy storage characteristics of the FESS. Two commercially manufactured metal flywheels with distinct energy storage characteristics are used as case studies to examine the potential benefit of using shape optimization in combination with operating speed, size, and material selection for rotor design. A sequential hybrid optimization strategy that combines a global genetic algorithm with a gradient-based local method is used to solve the rotor shape optimization problem. The choice of an optimal combination of operating speed and rotor radius, together with shape optimization, is demonstrated to provide 21–46% improvements in the energy capacity of two existing commercial FESS designs. Results show that self discharge losses in the rotor can be reduced by designing optimally shaped rotors with large radii operating at low speeds. It is advantageous, on an “energy-per-cost of material” basis, to use steel as the rotor material for optimally shaped flywheels with large radii operated at low speeds. Conversely, aluminium is a better choice of material for flywheels with smaller radii operated at high speeds.

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.

The production of a ferrofluid container, intended for use in the KRAKsat (CubeSat type) satellite in space conditions, is presented. Mechanized laser beam welding for AISI 316L stainless steel test joint and container prototype was developed and tested. The welded test joints were examined by non-destructive visual, penetration and radiographic testing and destructive testing by macro- and microscopic examination, static tensile test, static bending test, and hardness measurements. The welded container prototype was examined by leak test, temperature-vacuum test and vibration test. Test joints’ evaluation showed a proper selection of welding parameters and expected quality of joints. Austenitic microstructure with small δ-ferrite content in base materials, heat-affected zones, and welds guarantees sufficient mechanical properties for this part geometry. The tensile strength range of test joints was 687–729 MPa, hardness range was 140–200 HV3, and the bending angle was 180°. Welding of the prototype container and testing of tightness, resistance to temperature changes, and vibration were successful. Compliance with flywheel design and manufacturing requirements will enable the launch of a research satellite into orbit with such a wheel.

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.

Flywheel energy storage has a wide range of applications in energy grids and transportation. The adoption of high-performance components has made this technology a viable alternative for substituting or complementing other storage devices. Flywheel energy storage systems are subject to passive discharge attributed primarily to electrical machine losses, bearing rolling friction, and aerodynamic drag of the flywheel rotor. In the present study, measurements are presented for complete discharge experiments using a flywheel system featuring a vacuum enclosure. Best-fit equations were applied to the test data and compared to analytical models. Analysis of the best-fit equations indicates that they may serve as empirical models for approximating passive discharge under given conditions. Bearing losses, which varied linearly with velocity but were otherwise unaffected throughout the experiments, were larger than aerodynamic drag at low air pressures and low velocities. Aerodynamic drag became significant as velocity exceeded approximately 3400 rpm. The electrical machine was found to be the most significant source of passive discharge at all velocities and pressures. Based on these findings, it is recommended to maintain a low-pressure environment in the flywheel enclosure and to decouple the electrical machine from the rotor whenever possible to eliminate associated losses.

Bearingless switched reluctance motor (BSRM) has the advantages of high integration and low loss, and is especially suitable for flywheel batteries. In order to enhance the reliability and fault tolerance ability of BSRM, a novel dual-channel BSRM is proposed in this paper. This motor has the combined merits of switched reluctance motor and magnetic bearing, and can realize dual-channel fault-tolerant operation. The scalloped rotor poles are evenly distributed on the inner and outer walls of the rotor. All rotor poles are specially widened, which is benefit for raising the continuity of radial suspension force. Through the dual-phase-conduction decoupling control rules, the electromagnetic torque and suspension force can be generated simultaneously without serious coupling problem. The basic topology, operation principle, control method, and electromagnetic characteristics are analyzed. Field-circuit coupling joint simulation results of Simplorer and Maxwell confirm the feasibility of the proposed novel motor and the validity of decoupling control method.

Rolling bearings are widely used in rotating machinery and their failures may result in machine breakdown. Cage failure is of great concern because it may cause disassembly of bearing components. Since fault features of rolling bearing cage have characteristics of low frequency and small amplitude, which are often overwhelmed by strong noise and other irrelevant vibration components, there are a few research works about fault diagnosis of bearing cage, especially fault diagnosis of space bearing cage. Therefore, fault feature extraction of space bearing cage is a challenging topic. Toward this topic, a time-varying envelope filtering (TVEF) method is proposed in this article to extract the weak fault features of space bearing cage. Novel TVEF kernel functions are deduced by solving an envelope signal model, in which instantaneous frequencies (IFs) and instantaneous amplitudes (IAs) of signal components are modeled as redundant Fourier series. Fault characteristic components and their IFs and IAs can be accurately extracted by using TVEF kernel functions, which improve the signal-to-noise ratio of raw vibration signals. Based on the extracted IFs and IAs, a high-resolution time–frequency distribution is reconstructed to precisely extract the fault features of space bearing cage. Experiments designed in a flywheel test rig have verified the potential and effectiveness of the proposed TVEF method in exhibiting space bearing cage fault features than other existing methods.

Vernier-gimballing magnetically suspended flywheel is often used for attitude control and interference suppression of spacecrafts. Due to the special structure of the conical magnetic bearing, the radial component generated by the axial magnetic force and the change of the magnetic air gap will cause the nonlinearity of stiffness and disturbance. That will lead to not only poor stability of the suspension control system but also unsatisfactory tracking accuracy of the rotor position. To solve the nonlinear problem of the system, this article proposes a proportional–integral–derivative neural network control scheme. First, the rotor model considering the nonlinear variation of disturbance and stiffness parameters is established. Then, the weight of neural network is adjusted by the gradient descent method online to ensure the accurate output of magnetic force. Finally, the convergence analysis is carried out based on the Lyapunov stability theory. Compared with the general proportional–integral–derivative control and the radial basis function neural network control, the simulation results demonstrate that the proposed method has the highest tracking accuracy and excellent performance in improving stability. The experimental results prove the correctness of the theoretical analysis and the validity of the proposed method.

Undesired vibration force caused by harmonic currents is a common problem in a magnetically suspended flywheel (MSFW) rotor system. It poses a potential threat to system stability and performance degradation. In this work, multiple different phase-shift notch filters are connected in parallel mode to suppress the vibration harmonics. First, the multi-frequency vibrations in the MSFW is modelled and analysed. Then multiple different notch filters in parallel mode are proposed to plug into the baseline magnetically suspension system. The performance comparison with the conventional multiple notch filters is investigated. The parameters design and calculation for the proposed method are analysed in details. Moreover, the closed-loop stability of the overall system is given in the full speed range. Finally, simulation and experimental results for the MSFW demonstrate the superiority of the proposed method on both harmonics suppression and stability preservation.

The dual mass flywheel especially used in diesel engines has a structure in which the single- mass flywheel is divided into two parts and these two parts are combined with a curved helical spring. The flywheel is a part that reduces the speed fluctuations in the crankshaft of the internal combustion engines. In addition to this function, the dual mass flywheel dampens the torsional vibrations better than the clutch disc springs thanks to the spring system found in its structure. There are no torsional springs in the disc of the clutch system where dual mass flywheel is used. The dual mass flywheel is used with a rigid clutch disc without torsion springs. From this point of view, it is thought that the clutch dynamics of both systems are different. For this purpose, mathematical models of both systems were formed. The obtained models were solved after the appropriate transformations. As a result, it was seen the clutch engagement times are almost same in both systems. However in the clutch system where the dual mass flywheel is used the clutching process is performed more smoothly.

As the heavy-duty combustion engine development goes towards lower rotational speeds and higher cylinder pressures, the torsional vibrations increase. There is therefore a need to identify and study new types of vibration absorbers that can reduce the level of torsional vibrations transmitted from the engine to the gearbox. In this work, the concept of a dual-mass flywheel combined with a tuned vibration absorber is analysed. The tuned vibration absorber efficiently reduces the vibration amplitudes for engine load frequencies near the tuning frequency, but it also introduces an additional resonance into the system. By placing the tuned vibration absorber on an intermediate flange between the two dual-mass flywheels, the introduced resonance frequency will be lower than the tuning frequency and a resonance in operating engine speed range can be avoided. Numerical simulations are used to show how the torsional vibration amplitudes in a heavy-duty truck powertrain are affected by the tuned vibration absorber and how the different parameters of the tuned vibration absorber and the dual-mass flywheel affect the torsional vibrations and the resonance frequencies.

It is known that the synthesis of the relevant control law is performed and appropriate control devices are selected for specific tasks of controlling relative spacecraft motion. Flywheels, control moment gyroscopes, electromagnetic devices with permanent magnets and micro-jet engines are used as actuators in controlling the orientation and stabilizing the spacecraft. For example, flywheel motors together with electromagnets are most often used to ensure precise spacecraft stabilization in remote Earth monitoring (REM) problems. At the same time, there is a series of problems pertaining to the control over the relative motion of spacecraft where there is no need for precise spacecraft stabilization and ensuring minimal errors in orientation. These problems may include spacecraft orientation for charging solar batteries or orientation control for research and meteorological spacecraft. The study's purpose is to synthesize a law for spacecraft orientation control algorithm when using executive devices with permanent magnets (EDPM). EDPMs are the devices controlling spacecraft orientation. They consist of rotary permanent magnets, stepper motors, and capsule-screens with shutter flaps. Opening and closure of the capsule-screen flaps and rotation of permanent magnets in a certain way ensure the generation of a discrete control magnetic moment. It should be noted that EDPMs do not provide accurate spacecraft stabilization and hence they are not suitable for the REM purpose. However, EDPMs consume less on-board energy than other spacecraft orientation control systems and are useful in problems requiring less accurate stabilization. A control law was synthesized for controlling spacecraft equipped with EDPM using a nonlinear controller and a pulse-width modulator. Areas of effective EDPM application for various space-related problems including orientation and stabilization of aerodynamic elements perpendicular to the dynamic flow of the incoming atmosphere were determined. Advantages of using EDPMs in comparison with electromagnetic executive devices in the problems pertaining aerodynamic element stabilization in aerodynamic systems of deorbiting worked-out spacecraft from low Earth orbits were shown

A flywheel-like sensitive diaphragm, which breaks the sensitivity limitations imposed by the increased thickness and the decreased radius in edge-clamped circular structure, has been proposed and analyzed in fiber Fabry-Perot (FP) acoustic sensor. A new model is built around the effect of diaphragm's structure parameters on sensitivity of a fiber FP acoustic sensor with common ductile material. The proposed sensor based on flywheel-like stainless diaphragm in 5mm diameter and 0.035mm thickness has been fabricated and its acoustic performances were tested. The test results show that our acoustic sensor can realize acoustic measurement from 0.1 kHz to 19 kHz. The sensor exhibits an acoustic pressure sensitivity of 1.525nm/Pa at the frequency of 4.5 kHz. The noise-limited minimum detectable pressure (MDP) level of ~13.06μPa/√Hz@4.5kHz and the acoustic pressure signal-to-noise ratio (SNR) of 70.42dB@4.5kHz are achieved, respectively. And the mean SNR of cavity length variation of 62.43dB can be acquired over the entire frequency range. Comparing with the edge-clamped circular structure, the flywheel-like structure endows the common ductile sheet material the ability to response to acoustic pressure. Cost-effective and compact size give the proposed acoustic sensor a competitive edge, something of crucial importance to commercial applications.

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.

Flywheel Energy Storage Systems (FESSs) are commonly integrated with wind farms to help them to provide many grid services, including frequency control, voltage control, and power smoothing. Although such systems are not concerned by the severe grid code requirements, their ability to ride-through voltage dips is important to ensure better stability of the power grid. In this paper, the authors propose a robust H∞ current controller for a Wound Rotor Induction Machine (WRIM) based FESS during grid voltage dips. The proposed H∞ controller decreases the negative effects of voltage dips in the WRIM system, such as the rotor over-currents and the active power oscillations. On the other hand, it also guarantees the robustness in the presence of parameter perturbation. The proposed controller is designed using a modified mixed-sensitivity H∞ technique to take into consideration grid disturbances and parameter perturbation. Finally, simulations are made in MATLAB/Simulink using SimPowerSystems to verify the effectiveness of the H∞ controller under grid voltage dips with WRIM parameter perturbation. The simulation results show that the proposed H∞ controller can improve the stability of the WRIM based FESS subject to grid voltage dips and guarantee the robustness with parameter perturbation.

Generally the transmission can be considered as a mechanical system formed by a set of rigid links, the position and speed of which are determined by the problem of the law of motion of the engine crankshaft. The transmission of the car consists of a large number of flywheels which are interconnected by shafts, clutches and other elastic elements with different angular stiffness. These assembly units form a rather complex torsional oscillatory system with scattered parameters. Loads acting on the transmission of the car are due to environmental influences (macro- and micro-profile of the bearing surface, physical and mechanical properties of the soil, etc.) and fluctuations of the car itself, and are random.To determine the actual loads in its elements and the degree of non-uniformity of their motion, as well as finding the laws of this motion, it is necessary to take into account their elasticity and the impact of these processes on fuel consumption.The method of determining losses in the transmission of the car on the basis of the energy approach taking into account the operating conditions of armored vehicles of the NGU is proposed. The method should be based on a mathematical model of fuel consumption as the main source of energy, which takes into account the variety of operating conditions and follows from the theory of the car. Mechanical losses in the engine can be expressed through the magnitude of the piston stroke and crankshaft speed. The average effective pressure is determined by the force lost in the transmission and the force applied to the wheels of the car. The total moment of resistance of transmission given to driving wheels is presented in the form of two components: the moment caused by friction losses in knots transferring loadings (gearboxes, a transfer case, reducers of leading axles, cardan transfers), and the moment taking into account expenses energy for oil spraying in units (hydraulic losses). The total transmission losses consist of two main components: idling losses and torque transmission losses. Losses in transmission separately on units are defined by means of the special stands equipped with braking and loading devices. An important advantage of the method is the ability to obtain the equation of engine power balance and determine the efficiency of the transmission as a system with distributed parameters. Further research should be aimed at improving the mathematical model of fuel consumption, taking into account the calculated values of the transmission efficiency depending on the operating conditions of armored vehicles of the NGU., Пропонується метод визначення втрат у трансмісії автомобілів на основі енергетичного підходу з урахуванням умов експлуатації автобронетанкової техніки НГУ. Основою методу є математична модель витрати пального як основного джерела енергії, що враховує різноманіття умов експлуатації і випливає з теорії автомобіля. Важливою перевагою методу є можливість отримання рівняння балансу потужності двигуна та визначення коефіцієнта корисної дії трансмісії як системи з розподіленими параметрами.

In this paper, the reduction of vibration of dual mass flywheel (DMF) torsional damper under multiple working conditions is studied. Firstly, a 6DOF non-linear transmission system model including engine, DMF, gear pair of gearbox and clutch friction model is established. Secondly, a comprehensive multi-condition simulation strategy including ignition condition, idle condition, startup condition, drive condition, uniform speed condition and coast condition is designed to study the vibration reduction performance of DMF under different conditions. Then, the accuracy of the 6DOF non-linear transmission system model is verified. The simulation and test results showed that the accuracy of the model meets the engineering requirements. Finally, the effects of the performance parameters of the DMF on the torsional vibration of the transmission system under various operation conditions are studied. The results show that the performance of DMFs varies significantly under different conditions, and under drive condition the DMF has the best performance of vibration reduction. The free angle has less impact on the damping performance of the DMF, but other parameters have greater influence. The influence trend of the same parameter on the vibration reduction performance of DMF is different under different working conditions. Therefore, the parameter matching of the DMF cannot be based on one driving condition. It is necessary to comprehensively consider the vibration damping performance of the vehicle powertrain under multi-condition to match the parameters.

Due to the capacity of outputting both the high precision torque and the instantaneous large torque, the vernier-gimballing magnetically suspended flywheel (VGMSFW) is regarded as the key actuator for spacecraft. In this paper, a 5-DOF active VGMSFW is presented. The 3-DOF translation and 2-DOF deflection motions of the rotor are respectively realized by the spherical magnetic resistance magnetic bearings and the Lorentz magnetic bearing. The mathematical model of the deflection torque is established, and the decoupling between the 2-DOF deflections is demonstrated by the numerical analysis method. Compared with the conventional cylindrical magnetic bearings-rotor system, the spherical system is proven to eliminate the coupling between the rotor translation and deflection. In addition, a set of spherical magnetic resistance magnetic bearings with six-channel decoupling magnetic circuit are adopted to achieve the 3-DOF translation decoupling. The rotor dynamic model is derived, and the control system is established. The decoupling experiments and the torque experiments of the prototype are carried out. The results show that the decoupling among 5-DOF motions is realized and the instantaneous large torque can be obtained, which indicates that the requirements of the spacecraft can be highly satisfied by the spherical VGMSFW.

In this paper, a novel method to actively damp the powertrain vibration by utilizing a flywheel integrated starter generator (FISG) is proposed and validated on the testbench. A more light-weighted, economical, and compact hybrid powertrain devoid of clutches or dampers is built by replacing its flywheel with the ISG rotor. Motor torque having the opposite phase of the engine torque is applied to reduce the vibration. As opposed to the passive methods, which usually make use of the inertial and/or the damping properties of the components to absorb the vibration, this active approach is defined as active damping. Firstly, active damping is proved to be theoretically feasible by simulation based on an engine torque observer. To get the practical-application-oriented motor torque waveform, the observer torque is then processed by considering some realistic factors, such as the motor's response delay and the torque demand limit at MCU (Motor Control Unit), and is finally simplified as the rectangular waveform by off-line simulation. Secondly, an algorithm operating on the original resolver aimed at calculating the real-time crank position is proposed and programmed directly in the MCU. Finally, active damping is realized online utilizing a feedforward method by programming the crank-torque table in MCU. Experiments in both stable and transient conditions are conducted. Results show that active damping can attenuate the vibration effectively, especially over low speed and load ranges. The speed fluctuation range and the cyclic squared angular acceleration can be reduced by 79.7% and 89.7% respectively at 700 rpm when cranking. The crank vibration in transient conditions, including dragging and free deceleration, can also be suppressed, showing potential to realize fast and quiet engine start and halt.

We study a thermomechanical system comprising an alpha Stirling engine and a flywheel from the perspective of dynamical systems theory. Thermodynamics establishes a static relation between the flyw...

Power technology has long been the main problem that has plagued the realization of ocean exploration by autonomous underwater vehicles (AUVs). This paper introduces a new wave energy conversion device for AUV, which is sealed inside a closed floating body to avoid interaction with the marine environment. The system uses the gyroscopic effect to continuously convert the pitching motion of waves into electrical energy through flywheel rotation, and thus theoretically extend the endurance time of AUVs. In this paper, a mathematical model of the power generation device is established, and the effects caused by different parameters on the system behavior and energy output are analyzed. In order to reduce the cost of experiments, the energy conversion device is installed on an experimental platform that can simulate wave motion to observe its energy generation performance. The experimental results show that the established mathematical model can accurately reflect the real behavior of the power generation device on the platform under different wave conditions, and the energy output error is only 9.91%.

A novel dual‐phase‐conducted type bearingless switched reluctance flywheel motor is proposed, which has a hybrid outer rotor comprising circular segment and scalloped lamination segment, and only one set of winding is placed on each stator pole. In order to drive the flywheel to accelerate or slow down, two phases of windings in this motor conduct simultaneously. One phase provides radial suspension force, and the other phase provides electromagnetic torque. There exits satisfying decoupling between torque and suspension force. With the circular segment of the rotor, the continuity and stability of radial force can be enhanced. Finite element analysis results confirm the feasibility of the theoretical scheme.

Vertical rotors are often used as components of energy machines or flywheels for energy storage. Application of the contactless bearings makes it possible to minimize resistance against their rotation, wear, and energy losses. The advanced technological solution consists in utilization of permanent magnetic bearings or magnetic rings lifting the vertical rotors mounted in rolling element bearings to reduces their axial loading. The carried out research was focused on investigation of a rigid rotor supported at its upper end by a rolling element bearing inserted in a squeeze film damper and coupled with the stationary part by a shear magnetic bearing at its lower end. The bearaing is composed of two permanent magnets, one is attached to the stationary part and one to the rotor. The magnets are mutually attracted, which returns the rotor always to the equilibrium position during its vibration. In the developed computational procedure the rotor is represented by an absolutely rigid body and the permanent magnets by electric coils powered by equivalent current. The frequency response shows that application of the proposed magnetic bearing reduces amplitude of the rotor vibration in the range of lower velocities.

One important aspect of gait stability is the control of whole-body centroidal angular momentum H. We recently showed that if sensory-motor impairments affect a person's balance control, control of H can be assisted by control moment gyroscopes (CMGs). However, the effect of CMG technology inherently depends on the size and weight of these actuators, and on the speed of the flywheels they contain. These factors all pose challenges for wearable applications. Here, we show that it is possible to design CMGs light enough for wearable applications, while generating meaningful output torques. Our CMG, weighing 1.187 kg, can exert a peak torque of 15 N m with a torque-tracking bandwidth of 18 Hz. These results are partly due to an integrated model of components and partly to advancements in flywheel velocity control, allowing the speed to safely reach 20 000 rpm. These actuators open up new pathways of building wearable assistive devices for clinical applications.

This paper introduces an induction machine-based flywheel energy storage system (FESS) for direct integration with a variable-speed wind generator (VSWG). The aim is to connect the FESS at the DC bus level of a permanent magnet synchronous generator-based VSWG in order to stabilize the DC bus voltage as well as the power flowing into the grid. A rotor flux-oriented control strategy is proposed for the FESS converter based on the actual speed of the flywheel rotor. Since mechanical speed sensors are prone to failure and increase the maintenance cost of the system, a sensorless technique is proposed to estimate the rotor speed through a specially synthesized high-gain observer (HGO). The proposed observer achieves accurate tracking of the flywheel speed and flux and reduces the adverse effects of variations in the rated rotor resistance. Simulation results obtained using the MATLAB-Simulink environment are presented to illustrate the theoretical synthesis and analysis of the proposed FOC and sensorless HGO control strategies.

In this study, an improved centripetal force type-magnetic bearing (CFT-MB) for a flywheel battery system is proposed, which is easy to process and it has better performance with superior stiffness and anti-interference characteristics than that of the pure spherical CFT-MB. First, the configuration, magnetic circuits, working principle and mathematical model of the improved CFT-MB are analyzed in detail. The electromagnetic characteristics are then analyzed. In comparison with the analysis results of the pure spherical CFT-MB, the improved CFT-MB has less cost, less force–displacement and force–deflection stiffness, and higher force-current stiffness, which verify its preferable design concept. Related comparative experiments based on the prototype are also conducted. The stiffness tests results verify the accuracy of the previously presented electromagnetic characteristic analysis results. Performance tests results show that the proposed improved CFT-MB is superior to that of the original CFT-MB in resisting to the disturbance or the gyroscopic effect, which verifies the accuracy of the theoretical analysis.

Flywheel energy storage system (FESS) is new advanced machinery which is intended for electric power storage and release. A FESS, which is suitable for the small flywheel, was developed with a permanent magnet bearing (PMB) and a single point flexible support, and its friction loss is very low. By means of the Lagrange theory, a dynamic model was established. The Campbell diagram, mode shapes, modal damping ratios and critical speeds were designed after the flywheel data at different operating speeds was obtained by numerical simulation. Based on the excitation test and single freedom vibration theory, the stiffness and damping coefficient of the upper and lower damper was measured. The influences of damper dynamic parameters on modes of flywheel rotor bearing system were discussed in detail. The comparison between the calculated unbalance response and the experimental response indicates that the dynamic model is appropriate. The results showed that the lower damper absorbed vibration energy of the flywheel rotor, which increased vibration of the damping body. And the bigger damping coefficient had better vibration absorption effect. The developed FESS is simple, stable and efficient in structure.

To achieve high-precision position control for the active magnetic bearing high-speed flywheel rotor system (AMB-HFRS), a novel control strategy based on inverse system method and extended two-degree-of-freedom (2-DOF) proportional–integral–derivative (PID) controller is proposed in this study. First, the inverse system method is employed to decouple the AMB flywheel rotor system with strong non-linear and coupling, into four independent subsystems. Subsequently, extended 2-DOF PID controllers are used to regulate the decoupled subsystems, to obtain good performances of disturbance rejection and tracking simultaneously. In the extended 2-DOF PID controller, a differential signal is produced by a velocity observer to improve the ability of against noise. Finally, the characteristics of stability, tracking, disturbance rejection and robustness of the control strategy proposed are analysed in theory, and its ability and effectiveness to control the radial position of the AMB-HFRS are further studied by simulations and experiments. It is shown that the control strategy proposed can keep the AMB-HFRS suspending stably from static state to the speed of 24,000 rpm, has the advantages of good tracking, high disturbance rejection, strong robustness and good ability of against noise.

The aim of our project is to generate free energy using flywheel. A mains motor of two horsepower capacity is used to drive a series of belt and pulley drive which form a gear-train and produces over twice rpm at the shaft of an alternator. The intriguing thing about this system is that greater electrical output power can be obtained from the output of the alternator than appears to be drawn from the input motor. This is done with the help of Flywheel. The gravity wheel or flywheel is coupled with the gear-train in order to produce more excess energy or free energy. Detail study is done with various parameters of flywheel to obtain the maximum free energy out of the system.

This paper presents a new rotor design with assembled permeable retaining sleeve (APRS) to improve performances of a high speed permanent magnet synchronous machine (PMSM). The APRS consists of equal number of permeable and nonmagnetic parts, which are alternately arranged and assembled together circumferentially via keyways. Electromagnetic and mechanical characteristics of the rotor applied to a high speed flywheel PMSM are analyzed using finite element method. Machine performances are compared to an original design with commonly used rotor structure. It shows that phase inductance of the high speed machine increases dramatically due to smaller effective air gap, which may benefit suppressing inverter current harmonics. Also, permanent magnet usage reduces by 9.4 % to obtain identical back electromotive force and torque constant. In addition, a smaller skin depth owing to high-permeability material and the circumferential segmentation of the retaining sleeve effectively reduce rotor eddy current. Associated loss decreases by 40.7 % under open-circuit condition. A prototype rotor is fabricated and preliminary experimental tests are performed to confirm the analysis results.

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.

In this paper, a bipedal walking with push recovery balance control is proposed which involves posture correction of the robot. The biped robot could become unstable when it is under the influence of an external force. The method is proposed to achieve balance under such influence. Specifically, a set of force sensors are used to calculate the zero moment point, while a gyroscope and an accelerometer are used to estimate the inclination angle of the robot. Then, this sensor feedback is used to adjust the standing posture so that the robot can maintain the upright and stable state. Finally, an integral control for the static standing posture correction and a linear inverted pendulum with a flywheel model are developed for dynamic walking balance. The experimental results show that the proposed method enables the biped robot to achieve self-balance.

Our research goal is to construct a general predictive model for the design and control of a flywheel energy storage system (FESS) that utilizes a superconductor-permanent magnetic levitation bearing. The FESS machine design is a hubless field-regulated reluctance machine for which the rotor of the machine is also the rotating mass for the flywheel. Reported are the results of several experiments that show the oscillatory reactions of the levitated systems. For these experiments, the levitation height and the amount of flux penetrating the superconductor is controlled by adding mass to the levitated Halbach array and by the initial cooling conditions. A small impulsive force is delivered to the levitated array, which is then allowed to freely oscillate until it has completely decayed. From this we can find an effective spring constant and damping coefficient for the levitated system as a function of the magnetic field densities and levitation height. The goal of the experiments reported is to understand the dynamic behaviors of a levitation system and incorporate those properties into the control model for the flywheel. Initial experiments have demonstrated near critically damped harmonic behavior when a magnet array levitated by a superconductor is delivered an impulsive force. Using the data from our experiments we aim to gain knowledge of the underlying physics of the forces of interaction and to create a predictive macroscopic model based on magnetic array and YBCO properties. We compare our measured results to those obtained by using the advanced image mirror method and finite element magnetic modeling.

The hybrid energy storage system (HESS) plays an essential role in the shipboard medium-voltage dc (MVdc) system to provide backup power, buffer large load change, as well as improve power quality. In this paper, a novel virtual resistor and capacitor droop (VRCD) control is first proposed for HESS including battery, supercapacitor, and flywheel. It enables the generator and multiple types of energy storages (ESs) with different characteristics to respond to multiple-frequency unbalanced power instead of simple high-frequency and low-frequency power sharing by the conventional droop control method. A detailed design procedure for the VRCD control is presented. Also, the secondary state of charge recovery control is proposed to maintain high energy reserve of ESs for further power demand. Simulations are conducted to demonstrate the effectiveness of the control scheme proposed in a shipboard MVdc under particular loads fluctuation, such as the propulsion motor and the pulsed load.

As an efficient actuator for microvibration applications, a magnetically suspended rotor (MSR) system is always stymied by rotor mass imbalance and sensor runout, which will result in a harmonic disturbance in control current and further lead to severe periodic vibrations. In this paper, an odd-harmonic fractional repetitive control strategy is investigated for MSR systems to suppress odd-harmonic current with pertinence at low rotation speed. In contrast with conventional repetitive control (RC), only half of the delay units are required in the proposed control scheme. Therefore, it can achieve less computational burden and a faster convergence rate. Additionally, suppression accuracy of RC is vastly improved by adopting fractional delay filters, especially in fractional scenarios. The inset mode of RC is also modified for a simple system structure. Experimental results on a magnetically suspended flywheel are provided to validate the effectiveness of the proposed method.

Aiming at the heat fade of the continuous braking and low power density of traditional eddy current retarder (ECR) for heavy vehicles, a new liquid-cooled and flywheel-type eddy current retarder is proposed. The new ECR can keep a low working temperature because of the cooling type. It is assembled between the engine and the clutch, which can effectively improve the braking power density. The transient electromagnetic field of the ECR is solved by the finite-element method, and the braking torque characteristic curve is obtained. The thermal-fluid coupling field is analyzed using the computational fluid dynamics method. Finally, the structure parameters optimization of the rotor tooth is carried out. The braking torque increases by 14.8% and the weight of rotor tooth decreases by 9.5% after optimization. The test results show that the heat fade ratio of the new ECR braking torque is only 8.6%, but that of the traditional ECR is 46.7%.

In the magnetically suspended rotor (MSR) system of the flywheel, harmonic current produced mainly by mass imbalance and sensor runout would cause undesirable harmonic vibration. Resonant control (RSC) is one of the remarkable performance alternatives for rejecting a set of selected frequency components of the periodic disturbance in a control system. Based on the intrinsic relationship between RSC and repetitive control, which is deduced and clarified, this paper proposes a novel quasi-resonant control (QRSC) scheme for a baseline prestable MSR system to suppress the harmonic current. By introducing a damping factor, QRSC achieves a good balance between stability and dynamic performance. With hybrid phase compensation, it provides system absolute stability and expands the stability margin of the MSR system. Further, as the domination of harmonic current, low-order frequency components are suppressed by parallel QRSCs (PQRSC). A stability criterion with rigorous proof for the plug-in PQRSC-controlled MSR system is addressed as well. Experimental results obtained with a magnetically suspended flywheel prototype corroborate the theoretical approach.