| 1. |
- Huang, Zhifeng, et al.
(författare)
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Three-dimensional posture optimization for biped robot stepping over large ditch based on a ducted-fan propulsion system
- 2020
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Ingår i: IEEE International Conference on Intelligent Robots and Systems. - 2153-0858 .- 2153-0866. ; , s. 3591-3597
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Konferensbidrag (refereegranskat)abstract
- The recent progress of an ongoing project utilizing a ducted-fan propulsion system to improve a humanoid robot's ability to step over large ditches is reported. A novel method (GAS) based on the genetic algorithm with smoothness constraint can effectively minimize the thrust by optimizing the robot's posture during 3D stepping. The significant advantage of the method is that it can realize the continuity and smoothness of the thrust and pelvis trajectories. The method enables the landing point of the robot's swing foot to be not only in the forward but also in a side direction. The methods were evaluated by simulation and by being applied on a prototype robot, JetHR1. By keeping a quasistatic balance, the robot could step over a ditch with a span of 450 mm (as much as 97% of the length of the robot's leg) in 3D stepping.
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| 2. |
- Song, Kai, et al.
(författare)
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An Impedance Decoupling-Based Tuning Scheme for Wireless Power Transfer System under Dual-Side Capacitance Drift
- 2021
-
Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 36:7, s. 7526-7536
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Tidskriftsartikel (refereegranskat)abstract
- High performance of a wireless power transfer system is related to the resonance. However, the capacitance drift caused by temperature variation leads to detuning. In this article, a tuning scheme against dual-side capacitance drift using the impedance decoupling algorithm is investigated. First, the impact of the capacitance drift on transmission efficiency and output power are analyzed. Second, it is difficult to compensate for the dual-side capacitance drift quickly since the primary and secondary sides are coupled. Therefore, the impedance decoupling algorithm is introduced. The primary and secondary reactances are decoupled from the total impedance. The two independent reactances are only determined by the capacitance drift of the corresponding side. Then, by adjusting system frequency and the phase-shift angle of the semiactive rectifier, the reactances of both sides can be eliminated, respectively. Compared with the existing tuning methods focusing on total input impedance, the continuous adjustment on two sides is avoided, so the tuning time is significantly reduced. The experimental results prove that the proposed method can improve the system efficiency by 5%-40% and reduce the tuning time by 67% under different capacitance drift.
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| 3. |
- Yang, Guang, et al.
(författare)
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Improved Interoperability Evaluation Method for Wireless Charging Systems Based on Interface Impedance
- 2021
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 36:8, s. 8588-8592
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Tidskriftsartikel (refereegranskat)abstract
- The interoperability between the vehicle assembly (VA) and ground assembly (GA) of wireless charging systems has been specified in international standards. SAE J2954 first proposed an interoperability evaluation method based on interface impedance. However, the impedance measurement is challenging at high frequency since the phase difference between the voltage and current is not easy to measure accurately, especially when it is close to 90. Small errors in phase angle measurement are amplified in impedance calculation due to the sine/cosine function. This letter proposes an impedance measurement method using the power decomposition algorithm. By decomposing the input power into two orthogonal components, the impedance angle can be calculated without directly measuring the phase difference between the voltage and current. Thus, the measurement results of the impedance angle do not introduce errors. With the proposal, the high-cost probe or complex high-precision phase difference measurement circuit is not needed. The experimental results show that the conventional methods maximum relative error reaches 80%, making interoperability hard to determine. Reversely, with the proposed method, the relative error of impedance measurement is reduced to less than 10%.
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| 4. |
- Cao, Wenjing, et al.
(författare)
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Fuel consumption reduction effect of pre-acceleration before gliding of a vehicle with free-wheeling
- 2022
-
Ingår i: Control Theory and Technology. - : Springer Science and Business Media LLC. - 2198-0942 .- 2095-6983. ; 20:2, s. 235-247
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Tidskriftsartikel (refereegranskat)abstract
- Advanced fuel economy strategies are expected to reduce the fuel consumption of vehicles. An internal combustion engine (ICE) driving vehicle equipped with free-wheeling turns off the fuel injection and decouples the engine from the drivetrain when the driving force is not required. This paper proposes a method to reduce the fuel consumption of a vehicle equipped with free-wheeling. First, an optimization problem is formulated to minimize the fuel consumption of a vehicle with free-wheeling when the traveling distance, the initial and final speed are specified and the vehicle needs to glide before arriving at the end point for fuel economy. The speed profile of the vehicle, engine operating point, and engine on/off timing are obtained as the results of the optimization. The analytical and numerical analyses results demonstrate the effectiveness and the fuel-saving mechanism of the obtained speed profile. The main finding of the analyses is that rather than starting a gliding stage immediately after an acceleration or a constant speed stage, adding a pre-acceleration stage before the gliding stage is more fuel-economic under some conditions independent of the complexity of the vehicle model. The obtained speed profile including a pre-acceleration stage is applied to a driving scenario including traffic congestions. The results demonstrate the effectiveness of the pre-acceleration stage in reducing fuel consumption for a vehicle equipped with free-wheeling.
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| 5. |
- Han, Weiji, 1987, et al.
(författare)
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Analysis and Estimation of the Maximum Switch Current during Battery System Reconfiguration
- 2022
-
Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 69:6, s. 5931-5941
-
Tidskriftsartikel (refereegranskat)abstract
- Batteries are interconnected in series and/or parallel to meet wide-range power or energy demands in various industrial applications. To pursue the benefits of multiple connection structures in one system, reconfigurable battery systems (RBSs) have recently emerged for safe and efficient operation, extended energy storage and delivery, etc. Switches are the essential elements to enable the battery system reconfiguration, but selecting appropriate switches for RBS designs has not been systematically investigated. To bridge this gap, analytical expressions are derived in this paper to estimate the maximum switch current and its upper limit to facilitate the selection of RBS switches. An RBS prototype based on H-bridges is set up and experimental results verify the effectiveness and advantage of the proposed estimation method. These analytical expressions, relying only on resistances of batteries and switches, are readily applicable to practical RBS design and much more efficient than conducting numerous circuit experiments, simulation tests, or circuit analyses, especially for large-scale systems. Moreover, the analysis framework and estimation method proposed for series-parallel mutual conversion can be adaptively extended to other complex system reconfigurations to facilitate various RBS designs.
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| 6. |
- Huang, Xiaoliang, 1985, et al.
(författare)
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A Reconfigurable Battery Supercapacitor Hybrid Energy System with Active Balancing for Vehicle Applications
- 2021
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Ingår i: Proceedings - 2021 IEEE 19th International Power Electronics and Motion Control Conference, PEMC 2021. ; , s. 231-236
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Konferensbidrag (refereegranskat)abstract
- The concept of reconfigurable energy systems has become more and more popular in recent years for electric vehicle applications, which can largely enhance battery performance and extend battery lifetime. Active balancing is an advanced function realized by battery management systems (BMSs) to improve energy efficiencies and avoid potential over-charging risks. This paper proposed a reconfigurable hybrid energy system (HESS) that consists of one supercapacitor module, n lithium-ion modules, one DC/DC converter, and 3n switches, to enhance energy system performance with fast active balancing. The developed algorithms are to find out all possible configurations for a given lithium-ion module number and module section number, and the best configuration is selected based on the fastest balancing speed requirement. The proposed topology and algorithms are finally verified by simulations under standard vehicle driving cycles.
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| 7. |
- Huang, Xiaoliang, 1985, et al.
(författare)
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Experimental evaluation of conductor insulations used in e-mobility traction motors
- 2021
-
Ingår i: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 249-253
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Konferensbidrag (refereegranskat)abstract
- Application of high switching frequency converters providing signals with a high level of dv/dt has resulted in an increased stress on the traction motors insulation system. This paper presents an investigation done on the insulation materials developed for traction motors used in E-mobility applications and built using form or hairpin windings. Since the high dv/dt results in a high voltage difference between the conductors, focus in this paper is placed on the conductor insulation referred as 'primary insulation'. An experimental setup is developed and test samples using different insulation materials are made. A comparison between the life-time of the non-corona resistant and corona-resistant materials are made. Additionally, influence of the temperature, voltage and thickness on the insulation system life-time is evaluated. The test results show that corona resistant Kapton® ECRC materials with different thicknesses may be considered as proper candidates for traction motors designed and produced for electrification market fed by high switching frequency converters.
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| 8. |
- Jiang, Bowen, 1993, et al.
(författare)
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A New Battery Active Balancing Method with Supercapacitor Considering Regeneration Process
- 2020
-
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October:18 October 2020, s. 2364-2369
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Konferensbidrag (refereegranskat)abstract
- Lithium-ion batteries have been widely used in new energy vehicles (NEV) as large energy storage systems (ESS). It is necessary to balance series-connected cells to avoid over-charging or over-discharging as well as to improve the amount of usable energy. This paper starts with a comprehensive review of the existing strategies and gives a battery balancing category. A new balancing topology with its control algorithms is then introduced. A supercapacitor is used in the balancing circuit which replaces the highest state of charge (SOC) cell and is charged during the vehicle regeneration process. The supercapacitor also transfers energy to the lowest SOC cell after it is fully charged. This new strategy can not only improve the balancing efficiency due to fewer times of energy conversion but also reduce the required balancing time compared to single capacitor balancing.
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| 9. |
- Jiang, Bowen, 1993, et al.
(författare)
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A Novel Approach of Electric Powertrain Co-Simulation with High Fidelity Vehicle Model
- 2022
-
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2022-October
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a co-simulation approach for an electric vehicle which combines dynamic models of electric machine, inverter, gearbox in PLECS with high fidelity models of driver, autobody, wheel, road and environment in CarMaker. Lumped parameter thermal networks to model heat dissipation in the electric machine and the inverter are also included. The aim is to demonstrate versatility of the co-simulation method in analyzing effects of driver behaviors on thermal performance of electric machine and inverter. Co-simulation results using two simulation tools are compared to those obtained entirely using a single tool. It is observed that performing co-simulation using low fidelity vehicle model results in underestimation of vehicle speed. Further, the impacts of three different driver models on the temperatures of electric machine windings and semiconductor junctions are analyzed. Differences of 30% and 25% in the maximum temperature are observed respectively between an aggressive and a defensive driver.
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| 10. |
- Jiang, Bowen, 1993, et al.
(författare)
-
Accelerated destructive experiment design of motor stator winding insulation systems
- 2021
-
Ingår i: Proceedings - 2021 IEEE Workshop on Electrical Machines Design, Control and Diagnosis, WEMDCD 2021. ; , s. 225-230
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Konferensbidrag (refereegranskat)abstract
- Electric motors, being as key components in battery electric vehicles (BEVs), need to provide high power and torque to meet people's expectations on vehicles' performance. However, since the electric motors used in vehicles shall be driven by pulse width modulated (PWM) inverters, the high alternating voltages and currents applied to stator windings usually give extremely big electrical stress to their insulation systems, which may bring reductions to motors' lifetimes. Factors, such as environmental temperatures, voltage derivatives (dv/dt), insulation materials, and cover overlap percentages all affect the winding aging speeds in different degrees. To have shorter experimental time, this paper proposed a new method to do accelerated destructive experiments on insulation systems of motor stator windings. This designed method has stable measurements as well as precise detections on insulation failures and can study multiple insulation influencers. The functionalities of this insulation testing system have been finally verified by experiments using stator windings covered with Kapton® FN films.
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| 11. |
- Jiang, Bowen, 1993, et al.
(författare)
-
Real-Time FPGA/CPU-Based Simulation of a Full-Electric Vehicle Integrated with a High-Fidelity Electric Drive Model
- 2022
-
Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 15:5
-
Tidskriftsartikel (refereegranskat)abstract
- Real-time simulations refer to the simulations of a physical system where model equations for one time-step are solved within the same time period as in reality. An FPGA/CPU-based real-time simulation platform is presented in this paper, with a full-electric vehicle model implemented in a central processing unit (CPU) board and an electric drive model implemented in a field programmable gate arrays (FPGA) board. It has been a challenge to interface two models solved with two different processors. In this paper, one open-loop and three closed-loop interfaces are proposed. Real-time simulation results show that the best method is to transmit electric machine speed from the vehicle model to the electric derive model, with feedback electric machine torque calculated in FPGA. In addition, a virtual vehicle testing tool (CarMaker) is used when building the vehicle model, achieving more accurate modeling of vehicle subsystems. The presented platform can be used to verify advanced vehicle control functions during hardware-in-the-loop (HIL) testing. Vehicle anti-slip control is used as an example here. Finally, experiments were performed by connecting the real-time platform with a back-to-back electric machine test bench. Results of torque, rotor speed, and d&q axis currents are all in good agreement between simulations and experiments.
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| 12. |
- Lin, Runzi, et al.
(författare)
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Optimal scheduling management of the parking lot and decentralized charging of electric vehicles based on Mean Field Game
- 2022
-
Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 328
-
Tidskriftsartikel (refereegranskat)abstract
- As an intermediary for the interaction between the grid and electric vehicles (EVs), the parking lot aggregator not only facilitates the exchange of electricity between EVs and the grid, but also brings benefits to all participants. This paper proposes a linear quadratic (LQ) Mean Field Game (MFG) theory with a major player to optimal scheduling management of the parking lot and formulate optimal decentralized charging control strategies for a large number of EVs, to achieve the minimization of EVs charging cost while maximizing the profit of the parking lot, but these two problems are a set of coupled control problems. In addition to modeling the interaction between the parking lot and the EVs as a finite-time dynamic game problem, the Nash Certainty Equivalence (NCE) of related optimization problems is also proposed, and the corresponding solution algorithm is designed. The control effects of the proposed dynamic game problem on the charging cycle, as well as the effects of parameters change and electricity price fluctuations on charging control are illustrated through numerical simulations.
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| 13. |
- Liu, Huayang, et al.
(författare)
-
Cathode Pressure Control of Air Supply System for PEMFC
- 2021
-
Ingår i: IFAC-PapersOnLine. - : Elsevier BV. - 2405-8963 .- 2405-8963. ; 54:10, s. 247-252
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a backstepping method controller for the polymer electrolyte membrane fuel cell (PEMFC)air supply system. The control objective is adjusting the cathode pressure to its reference value quickly, in order to solve the problem of excessive extreme pressure difference between anode and cathode in practice. Considering model uncertainty and some disturbances, we design an extend state observer (ESO) to estimate disturbances. Next, a backstepping method is proposed to adjust control law. Finally, the experiment results demonstrate the effectiveness and robustness of the control strategy.
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| 14. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Circulating Current Reduction in Common DC-Link Power-HIL for Drives using SVM with Zero-Sequence Compensation
- 2020
-
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. ; , s. 4673-4678
-
Konferensbidrag (refereegranskat)abstract
- A new zero-sequence control technique is presented in this paper in order to eliminate the circulating current flowing in power hardware-in-the-loop test benches for electrical machine emulators. The machine emulator studied in this paper is made up of two three-phase inverters with an inductor connecting their ac-side. Both inverters share the same dc-link allowing circulating flow of the electric energy within this loop in order to emulate the operation of high power machine drives. Unfortunately, common-mode voltage is also freely developed within the loop and creates high circulating currents that act as a disturbance for the control of the inverters. Available control techniques have not managed to completely eliminate this current and common-mode filters are used additionally in order to solve the problem. The proposed zero-sequence control utilizes a modified version of the space vector modulation and reduces the circulating current amplitude up to 2.1% of the phase current, eliminating the need for hardware filters. Simulation results from Matlab/PLECS verify the effectiveness of the developed controller.
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| 15. |
- Nie, Linlin, et al.
(författare)
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Improved Nonlinear Extended Observer Based Adaptive Fuzzy Output Feedback Control for a Class of Uncertain Nonlinear Systems With Unknown Input Hysteresis
- 2023
-
Ingår i: IEEE Transactions on Fuzzy Systems. - 1941-0034 .- 1063-6706. ; 31:10, s. 3679-3689
-
Tidskriftsartikel (refereegranskat)abstract
- This study focuses on the problem of adaptive fuzzy dynamic surface output feedback control for a class of uncertain nonlinear systems subjected to unknown input hysteresis. A Prandtl-Ishlinskii (PI) model is applied to the uncertain nonlinear system for describing the unknown input hysteresis, making the controller design feasible. In addition, a nonlinear extended state observer (NESO) is designed for simultaneously estimating the unmeasurable states and generalized disturbances, including the nonlinear hysteresis term of the PI model and external disturbances. In addition, a novel nonlinear function is designed to replace fal(·) function of the general NESO to address a modification that increases the convergence speed. Considering the incorporation of the improved nonlinear extended state observer (INESO), an adaptive output feedback control scheme is proposed based on fuzzy logic system and dynamic surface techniques. A command filter is employed to avoid the 'explosion of complexity' problem inherent in the backstepping technique, while compensating the filtering error caused by adopting the filter. The Lyapunov approach is used to demonstrate the stability of the entire closed-loop system. Experiments regarding a piezoelectric micropositioning stage are conducted, the results of which illustrate that the proposed adaptive fuzzy output feedback control method can guarantee a satisfactory tracking performance.
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| 16. |
- Pehrman, Daniel, 1988, et al.
(författare)
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Loss Reduction by Synchronous Rectification in a 50 kW SiC-based Inductive Power Transfer System
- 2020
-
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October, s. 3907-3912
-
Konferensbidrag (refereegranskat)abstract
- With development in wide band-gap semiconductors, such as silicon carbide (SiC), inductive power transfer (IPT) has become a promising technology for charging electric vehicles (EV). To meet fast charging demands by consumers, higher power levels in IPT is required. The power in IPT is usually limited by thermal stress due to losses at the vehicle side. Synchronous rectification is an efficient way to reduce losses compared to passive rectification. In this paper, the loss reduction accounted to synchronous rectification is quantitatively evaluated. The level of reductions varies depending on the load level, primary voltage, and constant current or constant voltage (CCCV) operation. The analytical results support the simulation results for various operating points. The loss profiles are studied for different dc-link voltages and duty cycles. An 800 V, 50 kW dual-active bridge test setup with series-series compensation is constructed and experiments are done for verification. The setup is arranged in a back-to-back configuration with a common dc-link. Experimental result shows that losses are reduced by up to 60 % on the receiving side with synchronous rectification. At rated operation the losses are reduced by 100 W in the secondary side inverter.
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| 17. |
- Rodionov, Artem, 1990, et al.
(författare)
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Analysis of DC Link Current and Voltage Stress for Motor Drive Application in Dual Three-Phase Configuration
- 2020
-
Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October, s. 1267-1272
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Konferensbidrag (refereegranskat)abstract
- In automotive applications both space and operational safety of the drive-train are important design considerations. In this study a thorough DC link design for a fault tolerant dual three-phase drive train is conducted. PWM interleaving technique is utilized and based on the three-phase reference case DC link sizing maps in terms of both current and voltage stress are obtained for dual-three-phase configurations.It is found that current stress of the DC link capacitor can be reduced by up to 46 % compared to the three phase case. Similarly, the voltage stress can be reduced by up to 45 % while maintaining fault tolerant capability.
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| 18. |
- Sharma, Nimananda, 1988, et al.
(författare)
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Design of a power hardware-in-the-loop test bench for a traction permanent magnet synchronous machine drive
- 2020
-
Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. ; , s. 1765-1771
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Konferensbidrag (refereegranskat)abstract
- The challenges in inverter development for traction applications are low cost, better performance, optimized design and faster time to market. A solution is to use machine emulators whose phase currents and voltages at the terminal resembles a machine connected to a mechanical load for testing. Testing of an inverter for traction applications using permanent magnet synchronous machine (PMSM) emulator is presented. The emulator test bench consists of two identical front-to-front connected 2-level voltage source converters connected via an auxiliary inductor. Verification of the emulator is carried out in MATLAB/PLECS by comparing simulated phase currents, torque and rotor speeds to an equivalent PMSM drive. A common dc-link is used between the emulator and the inverter under test resulting into circulating common-mode currents. A common-mode choke and controller is used to eliminating common-mode currents. It is shown that the emulator can effectively emulate the PMSM drive with reasonable accuracy.
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| 19. |
- Song, Kai, et al.
(författare)
-
Constant Current Charging and Maximum System Efficiency Tracking for Wireless Charging Systems Employing Dual-Side Control
- 2020
-
Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 56:1, s. 622-634
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Tidskriftsartikel (refereegranskat)abstract
- Wireless power transfer (WPT) systems have attracted much attention because of their safety, convenience, and environmental friendliness. For wireless supercapacitor charging, the system efficiency and charging current are highly dependent on the load that varies over a wide range. In this article, a simultaneous maximum system efficiency (MSE) tracking and constant current (CC) charging control scheme for a supercapacitor is proposed. For CC charging, a double-sided LCC topology is chosen due to its characteristic of providing a load-independent output current. Furthermore, the impact of the coil internal resistance on the system characteristics (especially the charging current) is investigated, so a semiactive rectifier is introduced on the secondary side to achieve accurate CC charging and improve the system robustness. Based on the variable-step perturbation and observation algorithm, the MSE is tracked by searching for the minimum system input dc current using a primary-side buck converter on the premise that the charging current reaches its target value. The abovementioned two control loops are independent, and mutual communication is unnecessary when they cooperate; thus, the system is simplified. The simulation and experimental results show great consistency with the theoretical analysis. The experimental system maintains the MSE of 86% during charging the supercapacitor from 20 to 50 V with 2 A.
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| 20. |
- Wang, Yifan, et al.
(författare)
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Composite Data Driven-based Adaptive Control for a Piezoelectric Linear Motor
- 2022
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - 1557-9662 .- 0018-9456. ; 71
-
Tidskriftsartikel (refereegranskat)abstract
- Piezoelectric linear motors play an important role in ultra-precision manufacturing technology. However, the complex nonlinear relationship between the input and output of the piezoelectric linear motors limits their further application. In this paper, to achieve precise motion control for a piezoelectric linear motor, a composite data driven-based adaptive control method is proposed, consisting of a correction controller, model free adaptive controller (MFAC), and low pass filter. The proposed control method addresses the demand for a precise model of the piezoelectric linear motor and solely relies on the linear model and input/output measurement data. First, an experimental test is implemented to analyze the complex nonlinearity between input and output signals of the controlled system, and a correction control is employed based on the dynamic linear sub-model of the piezoelectric linear motor to improve its dynamic and static characteristics. Then, to avoid the influence of unmodeled dynamics, such as inherent nonlinearity and external vibration, a MFAC is established as a feedback controller using data driven technology. In addition, a low pass filter is incorporated into the feedback loop to eliminate high frequency measurement noise in the system, thus improving the transient response of the MFAC method. Finally, the theoretical analysis of the error convergence is presented. The effectiveness of the proposed method is verified via comparisons with a correction control method, correction control-based digital sliding-mode control method, and correction control-based MFAC method. The experimental results indicate that the proposed control method is suitable for engineering applications. In particular, the root-mean-square error (RMSE) for the third-order S-curve tracking using the proposed is reduced by more than 15%, compared with the RMSEs for the cases with contrast control methods.
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| 21. |
- Wang, Yifan, et al.
(författare)
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Time delay recursive neural network-based direct adaptive control for a piezo-actuated stage
- 2023
-
Ingår i: Science China Technological Sciences. - 1869-1900 .- 1674-7321. ; 66:5, s. 1397-1407
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Tidskriftsartikel (refereegranskat)abstract
- Piezo-actuated stage is a core component in micro-nano manufacturing field. However, the inherent nonlinearity, such as rate-dependent hysteresis, in the piezo-actuated stage severely impacts its tracking accuracy. This study proposes a direct adaptive control (DAC) method to realize high precision tracking. The proposed controller is designed by a time delay recursive neural network. Compared with those existing DAC methods designed under the general Lipschitz condition, the proposed control method can be easily generalized to the actual systems, which have hysteresis behavior. Then, a hopfield neural network (HNN) estimator is proposed to adjust the parameters of the proposed controller online. Meanwhile, a modular model consisting of linear submodel, hysteresis submodel, and lumped uncertainties is established based on the HNN estimator to describe the piezo-actuated stage in this study. Thus, the performance of the HNN estimator can be exhibited visually through the modeling results. The proposed control method eradicates the adverse effects on the control performance arising from the inaccuracy in establishing the offline model and improves the capability to suppress the influence of hysteresis on the tracking accuracy of piezo-actuated stage in comparison with the conventional DAC methods. The stability of the control system is studied. Finally, a series of comparison experiments with a dual neural networks-based data driven adaptive controller are carried out to demonstrate the superiority of the proposed controller.
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| 22. |
- Xun, Qian, 1990, et al.
(författare)
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An adaptive power split strategy with a load disturbance compensator for fuel cell/supercapacitor powertrains
- 2021
-
Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X. ; 44
-
Tidskriftsartikel (refereegranskat)abstract
- Electric vehicles powered by fuel cell and supercapacitor hybrid power sources are of great interest. However, the power allocation between each power source is challenging and the DC bus voltage fluctuation is relatively significant in cascaded PI control schemes. This paper develops a power control strategy with an adjustable cut-off frequency, using an artificial potential field, to adaptively split the load current between the fuel cell and the supercapacitor under various load conditions. The adaptive cut-off frequency is calculated by cutting the load frequency spectrum with an allocation ratio that changes with the supercapacitor state of charge. Therefore, the relatively lower frequency portion of the load current is provided by the fuel cell and the supercapacitor handles the higher frequency portion. To enhance the control performance of the DC bus voltage regulation against the load disturbance, a load disturbance compensator is introduced to suppress the DC bus voltage fluctuation when the load variation occurs, which is implemented by a feed-forward controller that can compensate the load current variation in advance. The effectiveness of the proposed strategy is validated by extensive experiments.
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| 23. |
- Xun, Qian, 1990, et al.
(författare)
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Drive Cycle Energy Efficiency of Fuel Cell/Supercapacitor Passive Hybrid Vehicle System
- 2021
-
Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 57:1, s. 894-903
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Tidskriftsartikel (refereegranskat)abstract
- The electric vehicle with passive hybridization of fuel cells and supercapacitors leads to lower cost and compactness due to the absence of DC/DC converters. This paper models such a vehicle and evaluates the energy efficiency of its powertrain system. The powertrain component losses, as functions of electric machine torque, speed and DC-link voltage, are modelled with a high level of detail which are verified against available test data. Compared to a pure fuel cell system, the fuel cell efficiency is higher when supercapacitors are introduced under pulse current load, and it is higher at lower current amplitude. As the pulse current frequency increases, the fuel cell efficiency also increases due to higher proportional current from the high-efficiency supercapacitors. A multiplicity of drive cycles is selected, divided into a low, middle, and high speed category to analyze the powertrain efficiency. The total powertrain energy efficiency varies between 53%-71% during propulsion for the studied drive cycles, whereas it is higher during braking ranging from 84% to 94%. The differences are closely related to the speed, acceleration, and DC-link voltage levels. The lower powertrain efficiency causes higher hydrogen consumption, leading to a reduced fuel cell efficiency at high speed, high acceleration and low DC-link voltage.
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| 24. |
- Xun, Qian, 1990, et al.
(författare)
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Intelligent Power Allocation with Load Disturbance Compensator in Fuel Cell/Supercapacitor System for Vehicle Applications
- 2020
-
Ingår i: ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo. - 9781728146294 ; , s. 489-494
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Konferensbidrag (refereegranskat)abstract
- A fuel cell-based hybrid power system with a supercapacitor can downsize the fuel cell power rating and shows good dynamic characteristics. However, power distribution between fuel cell and supercapacitor is challenging, and inappropriate power allocation strategy will easily cause over-charge or overdischarge of supercapacitor. Also, the DC bus voltage fluctuation is always encountered during the acceleration and deceleration of the vehicle. This paper proposes an intelligent power allocation method based on a low-pass filter. The adaptive cut-off frequency is applied to avoid over-charging and over-discharging the supercapacitor, and the cut-off frequency is calculated by cutting the load spectrum with allocation ratio changing with the state of charge (SoC) of the supercapacitor. A load disturbance compensator is also proposed to suppress the DC bus voltage fluctuation when the load variation occurs. According to the hybrid system model developed with commercially available devices, the feasibility of the strategy is verified by MATLAB/Simulink. The simulation results show that the SoC of the supercapacitor is effectively controlled and the DC bus voltage fluctuation is significantly reduced.
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| 25. |
- Yu, Yewei, et al.
(författare)
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Neural network based iterative learning control for magnetic shape memory alloy actuator with iteration-dependent uncertainties
- 2023
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Ingår i: Mechanical Systems and Signal Processing. - : Elsevier BV. - 0888-3270 .- 1096-1216. ; 187
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic shape memory alloy based actuator (MSMA-BA) is an indispensable component mechanism for high-precision positioning systems as it possesses the advantages of high precision, low energy consumption, and large stroke. However, hysteresis is an intrinsic property of MSMA material, which seriously affects the positioning accuracy of MSMA-BA. In this study, we propose a multi meta-model approach incorporating the nonlinear auto-regressive moving average with exogenous inputs (NARMAX) and Bouc–Wen (BW) models to describe the complex dynamic hysteresis of MSMA-BA. In particular, the BW model is introduced into the NARMAX model as an exogenous variable function, and a wavelet neural network (WNN) is adopted to construct the nonlinear function of the multi meta-model. In addition, iterative learning control is combined with a WNN to improve its convergence speed. A two-valued function is employed in the controller design process, so as to make use of history iteration information in updating control input. The main contribution of this study is the convergence analysis of the proposed iteration learning controller with iteration-dependent uncertainties (non-strict repetition of the initial state and varying iteration length). The experiments conducted on the MSMA-BA illustrate the validity of the proposed control scheme.
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