In an electric vehicle, a battery pack with many series-connected cells suffers from charge imbalances caused by manufacturing and varying operating conditions. The battery balancing system overcomes ...the cell imbalance while providing the required capacity maximization, prolonging the battery life, and safe operation. Various balancing topologies and control algorithms have been developed based on the difference in energy transfer methods. Among these, the passive balancing method is to convert the energy of the highly charged cell into heat. The active balancing method transfers the excessive energy of the high-charged cell to the low-charged cell through an electronic circuit. This type of balancing has high conversion efficiency compared to passive balancing and provides a noticeable improvement in increasing the useable capacity of the battery pack, thus increasing the range of the EVs. In this study, an optimal balancing control strategy for the active cell-to-pack balancing system has been developed. A unidirectional common flyback as a DC-DC converter has been used as a balancing circuit for transferring the excessive energy of the cells to the battery pack. The proposed optimal control algorithm eliminates the imbalances among battery packs in the minimum balancing time that ensures maximizing energy efficiency.
•NNLS- based optimal control for common flyback converter-based cell-to-pack battery balancing topology.•First study for balancing current control of common flyback converter-based balancing circuit.•Balancing time minimization has been achieved by optimal control strategy.•Efficient energy transfers for non-dissipative battery balancing circuit.•Compared with mean-differences control strategy, it has been obtained more better balancing performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mechanical balancing system driven by the motor can cause wrong adjustment and long balancing time in the controlling process, which will result in lower accuracy of rotation. In order to solve this ...problem and achieve more efficient online dynamic balance, the optimal moving path of the built-in mass block of balancing device can be determined by us. Four kinds of moving paths for mass block are designed by using for balancing to make experimental verification of spindle dynamic balance movement. By comparing experimental results of balance accuracy and balance efficiency, the optimal dynamic balancing strategy is determined. The results show that the designed moving strategy is reasonable, and the moving optimized path can carry out more accurate control precision and shorter adjustment time to achieve the expected effect. The better control strategy of dynamic balance lays the foundation for the high-precision operation of the spindle system.
A circuit for balancing Li-ion battery cells is proposed. This circuit requires one small transformer and N + 3 bilateral switches to equalize the charging states of N serially connected battery ...cells. The transformer works as an energy carrier, and the switches select two unbalanced cells that require an energy transfer from one to the other cell. The circuit was tested for a 12-cell Li-ion battery under static, cyclic, and dynamic charging/discharging conditions. Under static condition, the power-transfer efficiency was measured as 80.4% at a balancing power of 0.78 W; two 4400-mA·h battery cells at a state of charge (SOC) = 70 and 80% were equalized after 78 min. The results of cyclic and dynamic charging/discharging conditions show that the circuit is appropriate for balancing the Li-ion battery cells for vehicles and energy storage systems.
A disassembly line is an industrialized and automated production line which should be scheduled with high production efficiency. Although many disassembly line balancing optimization studies are ...contributed recently, they increase or reduce the number of workstations to balance the disassembly line. From real-world managerial settings, an increase or decrease workstations, is too expensive and not realistic. The bucket brigades' disassembly line is self-balancing and self-organizing, which is not constrained by the workstation beat time and only needs to distribute workers on the line according to certain rules to achieve line balancing after a period of time. In this paper, a bucket brigades disassembly line balancing optimization method considering uncertainty is proposed, in which a cloud model is used to represent the uncertain disassembly time. The proposed model handles multiple objectives including smoothness, disassembly cost and disassembly energy consumption to be minimized. To solve this complex problem, this study innovates a new heuristic method based on the social engineering optimizer as an enhanced local search metaheuristic. Finally, a ball collector is used to verify the effectiveness of the proposed method and extensive analysis is done to compare the performance of proposed model with other recent algorithms.
•Perfect static balancing using a geared mechanism with springs is presented.•Solutions are general, i.e., the key properties of springs are all considered.•Applications to balancing decoupled ...robotic manipulators are illustrated.•A mechanical prototype was built and experimentally tested.
This paper presents the static balancing designs (i.e., gravity compensation) for a rotating link by using a special straight-line geared mechanism with springs. The design scenario is to attach the rotating link yet to balance onto an inverted Cardan gear mechanism which has linear springs installed for balancing the weight of the links. It is found that the whole mechanism can be perfectly balanced in theory through either one or two linear springs. The significance of the proposed designs is that the derived solutions for perfect balancing are general. That is, (1) all the masses of the mechanism links are taken into account in the calculation for balancing, (2) the geometry of the design is formulated through the real-spring model (i.e., not zero-free-length springs), (3) the use of compression or extension springs is thoughtfully discussed, and (4) the installation points, preloaded lengths, initial tensions, and stiffness of the springs are considered altogether in the design process. Based on the original design, several design variations are suggested as well. Applications of the design for balancing two special robotic manipulators are illustrated. Last, an experimental test on a prototyped one-DoF balancer was performed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•First, the mathematical modelling of a manned two-wheeled vehicle is derived by using state space equation and the included perturbations are described in detail. Perturbation estimation technique ...is further adopted to provide with online estimations for perturbations.•Second, a hierarchical sliding mode control (HSMC) is used to handle the coupling effects and uncertainties of the underactuated two-wheeled vehicle, thus both balancing and velocity control purposes are achieved. Also, since most of the underactuated control systems only discuss the regulation not tracking problems, it is the first time that the HSMC is developed for the vehicle to achieve velocity tracking while balancing the chassis with driver around the upright position. The stability proof of the proposed scheme with PE is presented in detail.•Third, a group of experimental results for different driving situation (regulation task with slight and vigorous push, velocity tracking and balancing control on flat and inclined surfaces) are given to show the robust control performance of the proposed scheme, with convincing comparisons with the HSMC, adaptive HSMC and conventional linear feedback control. The readers can clearly see the significant improvements on balancing and velocity tracking performances by the proposed control.
This paper presents the design and implementation of hierarchical sliding mode control (HSMC) with perturbation estimation (PE) technique on a two-wheeled self-balancing vehicle (TWSBV), to simultaneously realize real-time balancing and velocity tracking control purposes. Considering the fact that the TWSBV system is a typical second-order underactuated system with one controlled actuator and two required control objectives, two sliding surfaces constructed by the velocity and tilt angle information are first designed and an HSMC is proposed to simultaneously achieve both balancing control and velocity control. In order to further enhance the ability of disturbance rejection of the HSMC control, the PE is used to assist with the proposed control for estimating the perturbations online such that the uncertainty bound information is not required in the control design. The excellent balancing and velocity tracking performance can be well achieved even under external disturbances. The effectiveness of the proposed control is verified by a group of comparative experimental investigations on a real TWSBV.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
New advanced power conversion systems play an essential role in the extension of range and life of batteries. This paper proposes a new modular multilevel converter with embedded electrochemical ...cells that achieves very low cell unbalancing without traditional balancing circuits and a negligible harmonic content of the output currents. In this new topology, the cells are connected in series by means of half-bridge converters, allowing high flexibility for the discharge and recharge of the battery. The converter features a cell balancing control that operates on each individual arm of the converter to equalize the state of charge of the cells. The paper shows that the proposed control does not affect the symmetry of the three-phase voltage output, even for significantly unbalanced cells. The viability of the proposed converter for battery electric vehicles and the effectiveness of the cell balancing control are confirmed by numerical simulations and experiments on a kilowatt-size prototype.
An active balancing circuit based on a buck--boost converter is proposed to deal with unbalanced states of battery packs. The proposed circuit has low-frequency bidirectional switches to control the ...states of inductors, including the connection, disconnection, and short-circuit states. By controlling the states of inductors, many kinds of buck-boost converters can be constructed between adjacent cells or groups of several adjacent cells. The proposed circuit has multiple balancing modes with flexible equalization paths, and different equalization processes can occur simultaneously to shorten equalization time. To improve the equalization performance of the proposed circuit, theoretical calculations are carried out to explore the relationship among different equalization parameters. A balancing strategy is presented to illustrate the sequence of equalization processes. Experiments are performed with a six-cell lithium iron phosphate battery pack under different operating conditions to verify the theoretical analysis.
This article presents a reduced switch hybrid multilevel converter (RSHMC). The proposed RSHMC is attractive for medium voltage industrial applications as it can work in a wide range of voltages, and ...lower switch count compared with other multilevel topologies. Nevertheless, the RSHMC faces challenges of neutral-point (NP) voltage, flying capacitor (FC) voltage balancing and input current distortion mitigation. Therefore, a four-layer coordinated control (FLCC) method is presented for the RSHMC in this article. Firstly, the relationship between voltage vector and current polarity of the RSHMC is analyzed in details, and the improper vectors are removed. Secondly, calculate the reference voltage in the αβ orthogonal coordinates frame. The voltage vectors are rotated to the first sector to reduce computational burden, and the optimal voltage vector is selected by cost function considering the current tracking. Thirdly, the redundant switching states of the optimal voltage vector are restored to the original sector of the reference voltage. Fourthly, the optimized switching state is selected for NP voltage and FC voltages balancing by the cost function considering voltage control. Through the aforementioned FLCC method, fast current tracking, input current distortion mitigation, NP voltage and FC voltage balancing can be realized simultaneously for the RSHMC. Finally, experiments and simulations verify that the proposed FLCC can effectively balance capacitor voltages and mitigate current distortions. Compared to the conventional MPC method, the current THD value and the computational time are reduced by 45% and 83% respectively.
This review is dedicated to balancing methods that are used to solve the rotor-balancing problem. To ensure a stable operation over an operating speed range, it is necessary to balance a rotor. The ...traditional methods, including the influence coefficient method (ICM) and the modal balancing method (MBM) are introduced, and the research progress, operation steps, advantages and disadvantages of these methods are elaborated. The classification of new balancing methods is reviewed. Readers are expected to obtain an overview of the research progress of existing balancing methods and the directions for future studies.
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