Considering the nonlinear, multifunctional properties of double-flywheel with closed- loop control, a two-step method including clustering and principal component analysis is proposed to detect the two faults in the m...Considering the nonlinear, multifunctional properties of double-flywheel with closed- loop control, a two-step method including clustering and principal component analysis is proposed to detect the two faults in the multifunctional flywheels. At the first step of the proposed algorithm, clustering is taken as feature recognition to check the instructions of ＂integrated power and attitude control＂ system, such as attitude control, energy storage or energy discharge. These commands will ask the flywheel system to work in different operation modes. Therefore, the relationship of parameters in different operations can define the cluster structure of training data. Ordering points to identify the clustering structure （OPTICS） can automatically identify these clusters by the reachability-plot. K-means algorithm can divide the training data into the corresponding operations according to the teachability-plot. Finally, the last step of proposed model is used to define the rela- tionship of parameters in each operation through the principal component analysis （PCA） method. Compared with the PCA model, the proposed approach is capable of identifying the new clusters and learning the new behavior of incoming data. The simulation results show that it can effectively detect the faults in the multifunctional flywheels system.展开更多
Traditional PID controllers are no longer suitable formagnetic-bearing-supported high-speed flywheels with significant gyroscopic effects. Becausegyroscopic effects greatly influence the stability of the flywheel roto...Traditional PID controllers are no longer suitable formagnetic-bearing-supported high-speed flywheels with significant gyroscopic effects. Becausegyroscopic effects greatly influence the stability of the flywheel rotor, especially at highrotational speeds. Velocity cross feedback and displacement cross feedback are used to overcomeharmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects. A control platform based on RTLinut and a PCis built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, theflywheel successfully runs at over 20000 r/min.展开更多
The centrifugal flywheel governor （CFG） is a mechanical device that automatically controls the speed of an engine and avoids the damage caused by sudden change of load torque. It has been shown that this system exhi...The centrifugal flywheel governor （CFG） is a mechanical device that automatically controls the speed of an engine and avoids the damage caused by sudden change of load torque. It has been shown that this system exhibits very rich and complex dynamics such as chaos. This paper investigates the problem of robust finite-time synchronization of non-autonomous chaotic CFGs. The effects of unknown parameters, model uncertainties and external disturbances are fully taken into account. First, it is assumed that the parameters of both master and slave CFGs have the same value and a suitable adaptive finite-time controller is designed. Second, two CFGs are synchronized with the parameters of different values via a robust adaptive finite-time control approach. Finally, some numerical simulations are used to demonstrate the effectiveness and robustness of the proposed finite-time controllers.展开更多
The existing research of the integrated power and attitude control system（IPACS） in satellites mainly focuses on the IPACS concept,which aims at solving the coupled problem between the attitude control and power tra...The existing research of the integrated power and attitude control system（IPACS） in satellites mainly focuses on the IPACS concept,which aims at solving the coupled problem between the attitude control and power tracking.In the IPACS,the configuration design of IPACS is usually not considered,and the coupled problem between two flywheels during the attitude control and energy storage has not been resolved.In this paper,an integrated power and single axis attitude control system using two counter rotating magnetically suspended flywheels mounted to an air table is designed.The control method of power and attitude control using flywheel is investigated and the coupling problem between energy storage and attitude control is resolved.A computer simulation of an integrated power and single axis attitude control system with two flywheels is performed,which consists of two counter rotating magnetically suspended flywheels mounted to an air rotary table.Both DC bus and a single axis attitude are the regulation goals.An attitude ＆ DC bus coordinator is put forward to separate DC bus regulation and attitude control problems.The simulation results of DC bus regulation and attitude control are presented respectively with a DC bus regulator and a simple PD attitude controller.The simulation results demonstrate that it is possible to integrate power and attitude control simultaneously for satellite using flywheels.The proposed research provides theory basis for design of the IPACS.展开更多
The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vecto...The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vector-based hybrid pulse width modulation） for a reduced harmonic distortion and switching loss. Associated electromagnetic interference mitigation and cooling requirements are significantly reduced. Voltage source inverter drives a three-phase MLC200 flywheel. The modularity of the proposed topology also simplifies overall system design and manufacturability. The system topology and control strategy are discussed. Simulation results are presented to illustrate the harmonic distortion and switching loss reduction and reduced line current ripple.展开更多
In this paper, the dynamic behavior analysis of the electromechanical coupling characteristics of a flywheel energy storage system （FESS） with a permanent magnet （PM） brushless direct-current （DC） motor （BLDCM...In this paper, the dynamic behavior analysis of the electromechanical coupling characteristics of a flywheel energy storage system （FESS） with a permanent magnet （PM） brushless direct-current （DC） motor （BLDCM） is studied. The Hopf bifurcation theory and nonlinear methods are used to investigate the generation process and mechanism of the coupled dynamic behavior for the average current controlled FESS in the charging mode. First, the universal nonlinear dynamic model of the FESS based on the BLDCM is derived. Then, for a 0.01 kWh/1.6 kW FESS platform in the Key Laboratory of the Smart Grid at Tianjin University, the phase trajectory of the FESS from a stable state towards chaos is presented using numerical and stroboscopic methods, and all dynamic behaviors of the system in this process are captured. The characteristics of the low-frequency oscillation and the mechanism of the Hopf bifurcation are investigated based on the Routh stability criterion and nonlinear dynamic theory. It is shown that the Hopf bifurcation is directly due to the loss of control over the inductor current, which is caused by the system control parameters exceeding certain ranges. This coupling nonlinear process of the FESS affects the stability of the motor running and the efficiency of energy transfer. In this paper, we investigate into the effects of control parameter change on the stability and the stability regions of these parameters based on the averaged-model approach. Furthermore, the effect of the quantization error in the digital control system is considered to modify the stability regions of the control parameters. Finally, these theoretical results are verified through platform experiments.展开更多
The latching control represents an attractive alternative to increase the power absorption of wave energy converters(WECs)by tuning the phase of oscillator velocity to the wave excitation phase.However,increasing the ...The latching control represents an attractive alternative to increase the power absorption of wave energy converters(WECs)by tuning the phase of oscillator velocity to the wave excitation phase.However,increasing the amplitude of motion of the floating body is not the only challenge to obtain a good performance of the WEC.It also depends on the efficiency of the power take-off system(PTO).This study aims to address the actual power performance and operation of a heaving point absorber with a direct mechanical drive PTO system controlled by latching.The PTO characteristics,such as the gear ratio,the flywheel inertia,and the electric generator,are analyzed in the WEC performance.Three cylindrical point absorbers are also considered in the present study.A wave-to-wire model is developed to simulate the coupled hydro-electro-mechanical system in regular waves.The wave energy converter(WEC)performance is analyzed using the potential linear theory but considering the viscous damping effect according to the Morison equation to avoid the overestimated responses of the linear theory near resonance when the latching control system is applied.The latching control system increases the mean power.However,the increase is not significant if the parameters that characterize the WEC provide a considerable mean power.The performance of the proposed mechanical power take-off depends on the gear ratio and flywheel.However,the gear ratio shows a more significant influence than the flywheel inertia.The operating range of the generator and the diameter/draft ratio of the buoy also influence the PTO performance.展开更多
This paper presents a theoretical and experimental study on controller design for the AMBs in a small-scale flywheel energy storage system,where the main goals are to achieve low energy consumption and improved rotord...This paper presents a theoretical and experimental study on controller design for the AMBs in a small-scale flywheel energy storage system,where the main goals are to achieve low energy consumption and improved rotordynamic stability.A H-infinity optimal control synthesis procedure is defined for the permanent-magnet-biased AMB-rotor system with 4 degrees of freedom.Through the choice of design weighting functions,notch filter characteristics are incorporated within the controller to reduce AMB current components caused by rotor vibration at the synchronous frequency and higher harmonics.Experimental tests are used to validate the controller design methodology and provide comparative results on performance and efficiency.The results show that the H-infinity controller is able to achieve stable rotor levitation and reduce AMB power consumption by more than 40%(from 4.80 to 2.64 Watts)compared with the conventional PD control method.Additionally,the H-infinity controller can prevent vibrational instability of the rotor nutation mode,which is prone to occur when operating with high rotational speeds.展开更多
Permanent magnet homopolar inductor machine(PMHIM) has attracted much attention in the field of flywheel energy storage system(FESS) due to its merits of simple structure,brushless excitation, and rotor flywheel integ...Permanent magnet homopolar inductor machine(PMHIM) has attracted much attention in the field of flywheel energy storage system(FESS) due to its merits of simple structure,brushless excitation, and rotor flywheel integration. However, the air-gap flux generated by the PM cannot be adjusted, which would cause large electromagnetic losses in the standby operation state of FESS. To solve this problem, a novel mechanically adjusted variable flux permanent magnet homopolar inductor machine with rotating magnetic poles(RMP-PMHIM) is proposed in this paper. The permanent magnet poles are rotated by an auxiliary rotating device and the purpose of changing the air-gap flux is achieved. First, the structure and operation principle of the proposed RMP-PMHIM are explained. Second,the flux weakening principle of the RMP-PMHIM is analyzed and the equivalent magnetic circuit models under different flux weakening states are built. Third, the parameters of the PM and its fixed structure are optimized to obtain the good electromagnetic performance. Fourth, the electromagnetic performance, including the air-gap flux density, back-EMF, flux weakening ability, loss, etc. of the proposed RMP-PMHIM are investigated and compared. Compared with the non-rotating state of the PM of RPM-PMHIM, the air-gap flux density amplitude can be weakened by 99.95% when the PM rotation angle is 90 degrees, and the no-load core loss can be suppressed by 99.98%,which shows that the proposed RPM-PMHIM is a good candidate for the application of FESS.展开更多
To extend the operating speed range of a conventional configuration of FESS （flywheel energy storage system）, an additional DC-DC boost converter is required between the machine and grid side converters to regulate ...To extend the operating speed range of a conventional configuration of FESS （flywheel energy storage system）, an additional DC-DC boost converter is required between the machine and grid side converters to regulate the output voltage. This paper presents a new FESS based on three-phase boost inverter topology. The proposed system facilitates voltage boost capability directly in a single-stage. The main advantage of the three-phase boost inverter is the deployment of only six switches and undersized passive elements to obtain a boosted AC output voltage weighed against the input DC supply. In this paper, FESS based on boost inverter topology is modeled and simulated using MATLAB/S1MULINK. An experimental setup has been built for the three-phase boost inverter to present its boosting capability. The simulation and experimental results sustain the proposed configuration.展开更多
This paper investigates the problem of two-stage extended Kalman filter （TSEKF）-based fault estimation for reaction flywheels in satellite attitude control systems （ACSs）. Firstly, based on the separate-bias princ...This paper investigates the problem of two-stage extended Kalman filter （TSEKF）-based fault estimation for reaction flywheels in satellite attitude control systems （ACSs）. Firstly, based on the separate-bias principle, a satellite ACSs with actuator fault is transformed into an augmented nonlinear discrete stochastic model; then, a novel TSEKF is suggested such that it can simultane- ously estimate satellite attitude information and actuator faults no matter they are additive or mul- tiplicative; finally, the proposed approach is respectively applied to estimating bias faults and loss of effectiveness for reaction flywheels in satellite ACSs, and simulation results demonstrate the effec- tiveness of the proposed fault estimation approach.展开更多
A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit. There are three identical flywheels orthogonally mounted on board. Each rotor is driven by a brushless DC motor ...A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit. There are three identical flywheels orthogonally mounted on board. Each rotor is driven by a brushless DC motor （BLDCM）. Models of spacecraft attitude dynamics and flywheel rotor driving motor electromechanics are discussed in detail. The controller design is similar to saturation limit linear assignment. An auxiliary parameter and a boundary coefficient are imported into the controller to guaran- tee system stability and improve control performance. A time-varying and state-dependent flywheel output torque saturation limit model is established. Stability of the closed-loop control system and asymptotic convergence of system states are proved via Lyapunov methods and LaSalle invariance principle. Boundedness of the auxiliary parameter ensures that the control objective can be achieved, while the boundary parameter＇s value makes a balance between system control performance and flywheel utilization efficiency. Compared with existing controllers, the newly developed controller with variable torque saturation limit can bring smoother control and faster system response. Numerical simulations validate the effectiveness of the controller.展开更多
Flywheel energy storage(FES) can have energy fed in the rotational mass of a flywheel,store it as kinetic energy,and release out upon demand.The superconducting energy storage flywheel comprising of magnetic and super...Flywheel energy storage(FES) can have energy fed in the rotational mass of a flywheel,store it as kinetic energy,and release out upon demand.The superconducting energy storage flywheel comprising of magnetic and superconducting bearings is fit for energy storage on account of its high efficiency,long cycle life,wide operating temperature range and so on.According to the high temperature superconducting(HTS) cooling mode,there are zero field cooling(ZFC) bearings and field cooling(FC) bearings.In practice,the superconducting bearings are formed by field-cooled superconductors and permanent magnets(PMs) generally.With respect to the forces between a permanent magnet and a superconductor,there are axial(thrust) bearings and radial(journal) bearings.Accordingly,there are two main types of high-temperature superconducting energy storage flywheels,and if a system comprising both the thrust bearing and the radial bearing will have the characteristics of both types of bearings.Magnetic force,magnetic stiffness and damping are these three main parameters to describe the levitation characteristics.Arrangement and shape of superconductors,thickness of superconductor,superconducting flux creep and critical current density of the superconductor affect the magnetic levitation force of these superconducting bearings.The key factors of FES technology,such as flywheel material,geometry,length and its support system were described,which directly influence the amount of energy storage and flywheel specific energy.All these results presented in this paper indicate that the superconducting energy storage flywheel is an ideal form of energy storage and an attractive technology for energy storage.展开更多
The control law of the flywheel in an integrated power and attitude control system （IPACS） for a spacecraft is investigated. The flywheels are used as attitude control actuators as well as energy storage device. A f...The control law of the flywheel in an integrated power and attitude control system （IPACS） for a spacecraft is investigated. The flywheels are used as attitude control actuators as well as energy storage device. A feedback control law for attitude tracking is firstly developed by using Lyapunov approach, and then a torque based control law of the flywheel is studied. The control torque vector of the flywheel is decomposed into three parts which are orthogonal to one another by using the method of singularity value decomposition （SVD）. One part is used to provide the attitude control torque, another part is used to store energy with given power, and the last part is used to accomplish wheel speed equalization to avoid wheel saturation caused by large difference among the wheel spin rates. A management scheme for energy storage power using kinetic energy feedback is proposed to keep energy balance, which can avoid wheel saturation caused by superfluous energy. Numerical simulation results demonstrate the effectiveness of the control scheme.展开更多
In the aerospace industry,the low-mass ultra-high-speed flywheel system play a critical role.In this paper,a kW-level Ultra-High Speed Permanent Magnet Synchronous Motor(UHSPMSM)as the core component of flywheel syste...In the aerospace industry,the low-mass ultra-high-speed flywheel system play a critical role.In this paper,a kW-level Ultra-High Speed Permanent Magnet Synchronous Motor(UHSPMSM)as the core component of flywheel system is proposed and analyzed with consideration of multiple physical fields,including electromagnetic characteristics,mechanical strength and rotor dynamics.The integrated support structure is put forward to improve rotation accuracy and operation stability of the UHSPMSM.Further,influence of the integrated support structure on critical speed is explored,and the key parameters such as support position and support stiffness are designed.Moreover,the rotor strength is analyzed by analytical model developed of rotor stress that can deal with multiple boundary types.Material and thickness of the sleeve are optimized,and range of interference value is accurately limited based on four extreme operating conditions.The 3-D Finite Element Model(FEM)is used to validate the strength characteristics and stress distribu-tion of rotor.A 1.5 kW-150000 r/min UHSPMSM with integrated support system is manufactured and tested.The feasibility of UHSPMSM proposed and the accuracy of analysis method are verified through electromagnetic,temperature rise and vibration characteristics test.The machine prototype realizes the load operation at rated speed and the multi-physical-field characteristics achieve the design specification.展开更多
Flywheel Energy Storage System (FESS) is used as an energy regeneration system to help with reducing peak power requirements on RTG cranes that are used to load or unload container ships. Nevertheless, with the use of...Flywheel Energy Storage System (FESS) is used as an energy regeneration system to help with reducing peak power requirements on RTG cranes that are used to load or unload container ships. Nevertheless, with the use of FESS, Port Operator can deploy undersized generator for new RTG as this will further reduce fuel consumption. This paper presents the investigation of the amount of energy and fuel consumption that can be reduced in Rubber Tyred Gantry (RTG) cranes in container terminals by the use of simulation. In addition, Variable Speed Generator is integrated to the simulation-hybridized RTG. Simulation results reveal that the total energy saving exceeded 30% relatively to conventional RTG. A hardware-in-loop system is introduced for the purpose of validating the simulation results. The hardware components procured include a FESS, a Variable Frequency Drive (VFD) and brake resistors.展开更多
Reaction flywheel is a significant actuator for satellites＇ attitude control. To improve output torque and rotational speed accuracy for reaction flywheel, this paper reviews the modeling and control approaches of DC...Reaction flywheel is a significant actuator for satellites＇ attitude control. To improve output torque and rotational speed accuracy for reaction flywheel, this paper reviews the modeling and control approaches of DC-DC converters and presents an application of the variable structure system theory with associated sliding regimes. Firstly, the topology of reaction flywheel is constructed. The small signal linearization process for a buck converter is illustrated. Then, based on the state averaging models and reaching qualification expressed by the Lee derivative, the general results of the sliding mode control （SMC） are analyzed. The analytical equivalent control laws for reaction flywheel are deduced detailedly by selecting various sliding surfaces at electromotion, energy consumption braking, reverse connection braking stages. Finally, numerical and experimental examples are presented for illustrative purposes. The results demonstrate that favorable agreement is established between the simulations and experiments. The proposed control strategy achieves preferable rotational speed regulation, strong rejection of modest disturbances, and high-precision output torque and rotational speed tracking abilities.展开更多
基金supported by the National Basic Research Program of China(No.2012CB720003)
文摘Considering the nonlinear, multifunctional properties of double-flywheel with closed- loop control, a two-step method including clustering and principal component analysis is proposed to detect the two faults in the multifunctional flywheels. At the first step of the proposed algorithm, clustering is taken as feature recognition to check the instructions of ＂integrated power and attitude control＂ system, such as attitude control, energy storage or energy discharge. These commands will ask the flywheel system to work in different operation modes. Therefore, the relationship of parameters in different operations can define the cluster structure of training data. Ordering points to identify the clustering structure （OPTICS） can automatically identify these clusters by the reachability-plot. K-means algorithm can divide the training data into the corresponding operations according to the teachability-plot. Finally, the last step of proposed model is used to define the rela- tionship of parameters in each operation through the principal component analysis （PCA） method. Compared with the PCA model, the proposed approach is capable of identifying the new clusters and learning the new behavior of incoming data. The simulation results show that it can effectively detect the faults in the multifunctional flywheels system.
文摘Traditional PID controllers are no longer suitable formagnetic-bearing-supported high-speed flywheels with significant gyroscopic effects. Becausegyroscopic effects greatly influence the stability of the flywheel rotor, especially at highrotational speeds. Velocity cross feedback and displacement cross feedback are used to overcomeharmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects. A control platform based on RTLinut and a PCis built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, theflywheel successfully runs at over 20000 r/min.
文摘The centrifugal flywheel governor （CFG） is a mechanical device that automatically controls the speed of an engine and avoids the damage caused by sudden change of load torque. It has been shown that this system exhibits very rich and complex dynamics such as chaos. This paper investigates the problem of robust finite-time synchronization of non-autonomous chaotic CFGs. The effects of unknown parameters, model uncertainties and external disturbances are fully taken into account. First, it is assumed that the parameters of both master and slave CFGs have the same value and a suitable adaptive finite-time controller is designed. Second, two CFGs are synchronized with the parameters of different values via a robust adaptive finite-time control approach. Finally, some numerical simulations are used to demonstrate the effectiveness and robustness of the proposed finite-time controllers.
基金supported by National Natural Science Foundation of China (Grant No. 60704025)
文摘The existing research of the integrated power and attitude control system（IPACS） in satellites mainly focuses on the IPACS concept,which aims at solving the coupled problem between the attitude control and power tracking.In the IPACS,the configuration design of IPACS is usually not considered,and the coupled problem between two flywheels during the attitude control and energy storage has not been resolved.In this paper,an integrated power and single axis attitude control system using two counter rotating magnetically suspended flywheels mounted to an air table is designed.The control method of power and attitude control using flywheel is investigated and the coupling problem between energy storage and attitude control is resolved.A computer simulation of an integrated power and single axis attitude control system with two flywheels is performed,which consists of two counter rotating magnetically suspended flywheels mounted to an air rotary table.Both DC bus and a single axis attitude are the regulation goals.An attitude ＆ DC bus coordinator is put forward to separate DC bus regulation and attitude control problems.The simulation results of DC bus regulation and attitude control are presented respectively with a DC bus regulator and a simple PD attitude controller.The simulation results demonstrate that it is possible to integrate power and attitude control simultaneously for satellite using flywheels.The proposed research provides theory basis for design of the IPACS.
文摘The operation of a motor drive for high-power, high-speed applications, especially for the permanent-magnet synchronous AC motors with regeneration capability is presented. Power system utilizes a SVHPWM （space-vector-based hybrid pulse width modulation） for a reduced harmonic distortion and switching loss. Associated electromagnetic interference mitigation and cooling requirements are significantly reduced. Voltage source inverter drives a three-phase MLC200 flywheel. The modularity of the proposed topology also simplifies overall system design and manufacturability. The system topology and control strategy are discussed. Simulation results are presented to illustrate the harmonic distortion and switching loss reduction and reduced line current ripple.
基金supported by the National Basic Research Program of China (Grant No. 2009CB2197)the National Natural Science Foundation of China (Grant No. 51177108)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110032110066)
文摘In this paper, the dynamic behavior analysis of the electromechanical coupling characteristics of a flywheel energy storage system （FESS） with a permanent magnet （PM） brushless direct-current （DC） motor （BLDCM） is studied. The Hopf bifurcation theory and nonlinear methods are used to investigate the generation process and mechanism of the coupled dynamic behavior for the average current controlled FESS in the charging mode. First, the universal nonlinear dynamic model of the FESS based on the BLDCM is derived. Then, for a 0.01 kWh/1.6 kW FESS platform in the Key Laboratory of the Smart Grid at Tianjin University, the phase trajectory of the FESS from a stable state towards chaos is presented using numerical and stroboscopic methods, and all dynamic behaviors of the system in this process are captured. The characteristics of the low-frequency oscillation and the mechanism of the Hopf bifurcation are investigated based on the Routh stability criterion and nonlinear dynamic theory. It is shown that the Hopf bifurcation is directly due to the loss of control over the inductor current, which is caused by the system control parameters exceeding certain ranges. This coupling nonlinear process of the FESS affects the stability of the motor running and the efficiency of energy transfer. In this paper, we investigate into the effects of control parameter change on the stability and the stability regions of these parameters based on the averaged-model approach. Furthermore, the effect of the quantization error in the digital control system is considered to modify the stability regions of the control parameters. Finally, these theoretical results are verified through platform experiments.
基金The authors acknowledge the support from the Brazilian Research Council(CNPq),contract numbers 380950/2018-9(INEOF-National Institute for Ocean and River Energy)and 305657/2017-8,respectivelySpecial thanks to FAPERJ for the support of the wave energy research at the Subsea Technology Lab(COPPE),contract number E-26/202.600/2019。
文摘The latching control represents an attractive alternative to increase the power absorption of wave energy converters(WECs)by tuning the phase of oscillator velocity to the wave excitation phase.However,increasing the amplitude of motion of the floating body is not the only challenge to obtain a good performance of the WEC.It also depends on the efficiency of the power take-off system(PTO).This study aims to address the actual power performance and operation of a heaving point absorber with a direct mechanical drive PTO system controlled by latching.The PTO characteristics,such as the gear ratio,the flywheel inertia,and the electric generator,are analyzed in the WEC performance.Three cylindrical point absorbers are also considered in the present study.A wave-to-wire model is developed to simulate the coupled hydro-electro-mechanical system in regular waves.The wave energy converter(WEC)performance is analyzed using the potential linear theory but considering the viscous damping effect according to the Morison equation to avoid the overestimated responses of the linear theory near resonance when the latching control system is applied.The latching control system increases the mean power.However,the increase is not significant if the parameters that characterize the WEC provide a considerable mean power.The performance of the proposed mechanical power take-off depends on the gear ratio and flywheel.However,the gear ratio shows a more significant influence than the flywheel inertia.The operating range of the generator and the diameter/draft ratio of the buoy also influence the PTO performance.
基金supported by Thailand Science Research and Innovation and the National Research Council of Thailand under Grant RGU6280014.
文摘This paper presents a theoretical and experimental study on controller design for the AMBs in a small-scale flywheel energy storage system,where the main goals are to achieve low energy consumption and improved rotordynamic stability.A H-infinity optimal control synthesis procedure is defined for the permanent-magnet-biased AMB-rotor system with 4 degrees of freedom.Through the choice of design weighting functions,notch filter characteristics are incorporated within the controller to reduce AMB current components caused by rotor vibration at the synchronous frequency and higher harmonics.Experimental tests are used to validate the controller design methodology and provide comparative results on performance and efficiency.The results show that the H-infinity controller is able to achieve stable rotor levitation and reduce AMB power consumption by more than 40%(from 4.80 to 2.64 Watts)compared with the conventional PD control method.Additionally,the H-infinity controller can prevent vibrational instability of the rotor nutation mode,which is prone to occur when operating with high rotational speeds.
基金supported in part by the National Natural Science Foundation of China under Grant 52007055in part by the Natural Science Foundation of Hunan Province of China under Grant 2021JJ40099。
文摘Permanent magnet homopolar inductor machine(PMHIM) has attracted much attention in the field of flywheel energy storage system(FESS) due to its merits of simple structure,brushless excitation, and rotor flywheel integration. However, the air-gap flux generated by the PM cannot be adjusted, which would cause large electromagnetic losses in the standby operation state of FESS. To solve this problem, a novel mechanically adjusted variable flux permanent magnet homopolar inductor machine with rotating magnetic poles(RMP-PMHIM) is proposed in this paper. The permanent magnet poles are rotated by an auxiliary rotating device and the purpose of changing the air-gap flux is achieved. First, the structure and operation principle of the proposed RMP-PMHIM are explained. Second,the flux weakening principle of the RMP-PMHIM is analyzed and the equivalent magnetic circuit models under different flux weakening states are built. Third, the parameters of the PM and its fixed structure are optimized to obtain the good electromagnetic performance. Fourth, the electromagnetic performance, including the air-gap flux density, back-EMF, flux weakening ability, loss, etc. of the proposed RMP-PMHIM are investigated and compared. Compared with the non-rotating state of the PM of RPM-PMHIM, the air-gap flux density amplitude can be weakened by 99.95% when the PM rotation angle is 90 degrees, and the no-load core loss can be suppressed by 99.98%,which shows that the proposed RPM-PMHIM is a good candidate for the application of FESS.
文摘To extend the operating speed range of a conventional configuration of FESS （flywheel energy storage system）, an additional DC-DC boost converter is required between the machine and grid side converters to regulate the output voltage. This paper presents a new FESS based on three-phase boost inverter topology. The proposed system facilitates voltage boost capability directly in a single-stage. The main advantage of the three-phase boost inverter is the deployment of only six switches and undersized passive elements to obtain a boosted AC output voltage weighed against the input DC supply. In this paper, FESS based on boost inverter topology is modeled and simulated using MATLAB/S1MULINK. An experimental setup has been built for the three-phase boost inverter to present its boosting capability. The simulation and experimental results sustain the proposed configuration.
文摘This paper investigates the problem of two-stage extended Kalman filter （TSEKF）-based fault estimation for reaction flywheels in satellite attitude control systems （ACSs）. Firstly, based on the separate-bias principle, a satellite ACSs with actuator fault is transformed into an augmented nonlinear discrete stochastic model; then, a novel TSEKF is suggested such that it can simultane- ously estimate satellite attitude information and actuator faults no matter they are additive or mul- tiplicative; finally, the proposed approach is respectively applied to estimating bias faults and loss of effectiveness for reaction flywheels in satellite ACSs, and simulation results demonstrate the effec- tiveness of the proposed fault estimation approach.
基金National Natural Science Foundation of China(10902003)
文摘A new attitude controller is proposed for spacecraft whose actuator has variable input saturation limit. There are three identical flywheels orthogonally mounted on board. Each rotor is driven by a brushless DC motor （BLDCM）. Models of spacecraft attitude dynamics and flywheel rotor driving motor electromechanics are discussed in detail. The controller design is similar to saturation limit linear assignment. An auxiliary parameter and a boundary coefficient are imported into the controller to guaran- tee system stability and improve control performance. A time-varying and state-dependent flywheel output torque saturation limit model is established. Stability of the closed-loop control system and asymptotic convergence of system states are proved via Lyapunov methods and LaSalle invariance principle. Boundedness of the auxiliary parameter ensures that the control objective can be achieved, while the boundary parameter＇s value makes a balance between system control performance and flywheel utilization efficiency. Compared with existing controllers, the newly developed controller with variable torque saturation limit can bring smoother control and faster system response. Numerical simulations validate the effectiveness of the controller.
基金the Postdoctoral Foundation of China(No. 20060400389)the National High Technology Research and Development Program (863) of China(No. 2006AA05Z241)
文摘Flywheel energy storage(FES) can have energy fed in the rotational mass of a flywheel,store it as kinetic energy,and release out upon demand.The superconducting energy storage flywheel comprising of magnetic and superconducting bearings is fit for energy storage on account of its high efficiency,long cycle life,wide operating temperature range and so on.According to the high temperature superconducting(HTS) cooling mode,there are zero field cooling(ZFC) bearings and field cooling(FC) bearings.In practice,the superconducting bearings are formed by field-cooled superconductors and permanent magnets(PMs) generally.With respect to the forces between a permanent magnet and a superconductor,there are axial(thrust) bearings and radial(journal) bearings.Accordingly,there are two main types of high-temperature superconducting energy storage flywheels,and if a system comprising both the thrust bearing and the radial bearing will have the characteristics of both types of bearings.Magnetic force,magnetic stiffness and damping are these three main parameters to describe the levitation characteristics.Arrangement and shape of superconductors,thickness of superconductor,superconducting flux creep and critical current density of the superconductor affect the magnetic levitation force of these superconducting bearings.The key factors of FES technology,such as flywheel material,geometry,length and its support system were described,which directly influence the amount of energy storage and flywheel specific energy.All these results presented in this paper indicate that the superconducting energy storage flywheel is an ideal form of energy storage and an attractive technology for energy storage.
文摘The control law of the flywheel in an integrated power and attitude control system （IPACS） for a spacecraft is investigated. The flywheels are used as attitude control actuators as well as energy storage device. A feedback control law for attitude tracking is firstly developed by using Lyapunov approach, and then a torque based control law of the flywheel is studied. The control torque vector of the flywheel is decomposed into three parts which are orthogonal to one another by using the method of singularity value decomposition （SVD）. One part is used to provide the attitude control torque, another part is used to store energy with given power, and the last part is used to accomplish wheel speed equalization to avoid wheel saturation caused by large difference among the wheel spin rates. A management scheme for energy storage power using kinetic energy feedback is proposed to keep energy balance, which can avoid wheel saturation caused by superfluous energy. Numerical simulation results demonstrate the effectiveness of the control scheme.
基金supported in part by the National Natural Science Foundation of China(No.52177048)the Natural Science Foundation of Jiangsu Province,China(No.BK20201297)+1 种基金the University Science Research Project of Jiangsu Province,China(No.21KJB120003)the Industry University Research Cooperation Project of Jiangsu Province,China(No.BY2021358).
文摘In the aerospace industry,the low-mass ultra-high-speed flywheel system play a critical role.In this paper,a kW-level Ultra-High Speed Permanent Magnet Synchronous Motor(UHSPMSM)as the core component of flywheel system is proposed and analyzed with consideration of multiple physical fields,including electromagnetic characteristics,mechanical strength and rotor dynamics.The integrated support structure is put forward to improve rotation accuracy and operation stability of the UHSPMSM.Further,influence of the integrated support structure on critical speed is explored,and the key parameters such as support position and support stiffness are designed.Moreover,the rotor strength is analyzed by analytical model developed of rotor stress that can deal with multiple boundary types.Material and thickness of the sleeve are optimized,and range of interference value is accurately limited based on four extreme operating conditions.The 3-D Finite Element Model(FEM)is used to validate the strength characteristics and stress distribu-tion of rotor.A 1.5 kW-150000 r/min UHSPMSM with integrated support system is manufactured and tested.The feasibility of UHSPMSM proposed and the accuracy of analysis method are verified through electromagnetic,temperature rise and vibration characteristics test.The machine prototype realizes the load operation at rated speed and the multi-physical-field characteristics achieve the design specification.
文摘Flywheel Energy Storage System (FESS) is used as an energy regeneration system to help with reducing peak power requirements on RTG cranes that are used to load or unload container ships. Nevertheless, with the use of FESS, Port Operator can deploy undersized generator for new RTG as this will further reduce fuel consumption. This paper presents the investigation of the amount of energy and fuel consumption that can be reduced in Rubber Tyred Gantry (RTG) cranes in container terminals by the use of simulation. In addition, Variable Speed Generator is integrated to the simulation-hybridized RTG. Simulation results reveal that the total energy saving exceeded 30% relatively to conventional RTG. A hardware-in-loop system is introduced for the purpose of validating the simulation results. The hardware components procured include a FESS, a Variable Frequency Drive (VFD) and brake resistors.
基金supported by the National Natural Science Foundation of China(No.61121003)
文摘Reaction flywheel is a significant actuator for satellites＇ attitude control. To improve output torque and rotational speed accuracy for reaction flywheel, this paper reviews the modeling and control approaches of DC-DC converters and presents an application of the variable structure system theory with associated sliding regimes. Firstly, the topology of reaction flywheel is constructed. The small signal linearization process for a buck converter is illustrated. Then, based on the state averaging models and reaching qualification expressed by the Lee derivative, the general results of the sliding mode control （SMC） are analyzed. The analytical equivalent control laws for reaction flywheel are deduced detailedly by selecting various sliding surfaces at electromotion, energy consumption braking, reverse connection braking stages. Finally, numerical and experimental examples are presented for illustrative purposes. The results demonstrate that favorable agreement is established between the simulations and experiments. The proposed control strategy achieves preferable rotational speed regulation, strong rejection of modest disturbances, and high-precision output torque and rotational speed tracking abilities.
