scholarly journals Research on Equalization Control Strategy of Marine Lithium Battery Pack

2021 ◽  
Vol 2137 (1) ◽  
pp. 012020
Author(s):  
Qi Sun ◽  
Yi Quo

Abstract With the widespread use of clean energy in ship electric power systems, marine lithium battery systems are becoming more and more popular. Aiming at the problems between the individual cells in the lithium battery pack, such as inconsistency in voltage, capacity, and internal resistance, the state of charge (SOC) of battery is selected as the equalization control variable, an equalization topology structure based on SOC for battery connecting or bypassing is designed. The equilibrium control strategy fusing model predictive control (MPC) algorithm and time-sequence control algorithm is adopted. The simulation model is built on the MATLAB/Simulink platform, and the different value combinations of two equalization parameters (i.e., equalization period T and number of batteries connected to the battery pack q) were simulated and analyzed. The results show that the designed equalization control strategy can quickly and accurately achieve SOC equalization, by optimizing two key parameters, the equalization accuracy and equalization speed of the marine lithium battery pack can be improved, also the energy loss in the equalization process can be reduced.

2019 ◽  
Vol 9 (7) ◽  
pp. 1484 ◽  
Author(s):  
Xiangwu Yan ◽  
Weichao Zhang

Due to the irreversible energy substitution from fossil fuels to clean energy, the development trend of future power systems is based on renewable energy generation. However, due to the incompatibility of converter-based non-dispatchable renewable energy generation, the stability and reliability of traditional power systems deteriorate as more renewables are introduced. Since conventional power systems are dominated by synchronous machines (SM), it is natural to utilize a virtual synchronous generator (VSG) control strategy that intimates SM characteristics on integrated converters. The VSG algorithm developed in this paper originates from mimicking mathematic models of synchronous machines. Among the different models of implementation, the second-order model is simple, stable, and compatible with the control schemes of current converters in traditional power systems. The VSG control strategy is thoroughly researched and case studied for various converter-interfaced systems that include renewable generation, energy storage, electric vehicles (EV), and other energy demands. VSG-based integration converters can provide grid services such as spinning reserves and inertia emulation to the upper grids of centralized plants, distributed generation networks, and microgrids. Thus, the VSG control strategy has paved a feasible way for an evolutionary transition to a power electronics-based future power grid. By referring to the knowledge of traditional grids, a hierarchical system of operations can be established. Finally, generation and loads can be united in universal compatibility architecture under consolidated synchronous mechanisms.


2021 ◽  
Vol 23 (3) ◽  
pp. 221-228
Author(s):  
Raaed Faleh Hassan ◽  
Suha Sabah Shyaa

In recent decades, multi-level converters have become popular and used in many power systems applications. Compared with conventional converters, multi-level converters contribute to reducing the voltage stress on the switching devices and enhancing the power quality delivered to the load. In this paper, the study of the five-level diode clamped multilevel converter based static synchronous compensator has been accomplished. Model Predictive current control strategy which a type of modern control algorithms was employed for driving the proposed compensator. The suggested five level converter controlled by model predictive current control is firstly examined to verify that this control algorithm is appropriate for achieving the desired performance. Then the proposed converter and control combination is employed and simulated as a static synchronous compensator in distributed power system. Moreover, in order to examine the robustness of this compensator, the load status is suggested to be heavy inductive. Simulation process has been performed using MATLAB – SIMULINK software package. The results show that the implemented configuration (converter and control algorithm) provides high power quality improvement with adequate reactive power compensation.


2014 ◽  
Vol 721 ◽  
pp. 20-23
Author(s):  
Liang Chu ◽  
Chong Guo ◽  
Yi Yang ◽  
Zi Cheng Fu ◽  
Yuan Jian Zhang

In order to avoid the nonreversible damage to the batteries because of over discharge when the pure electric vehicle is moving, this article proposes a driving control strategy in limp mode due to under voltage. Firstly, research the discharge characteristics of the lithium battery pack. Secondly research and develop the control strategy that limit the motor torque by the closed-loop control of voltage. Finally develop the strategy model using MATLAB/Simulink, and finish the verification test and prove the control strategy effectiveness by offline simulation.


Electronics ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1448
Author(s):  
Nam-Gyu Lim ◽  
Jae-Yeol Kim ◽  
Seongjun Lee

Battery applications, such as electric vehicles, electric propulsion ships, and energy storage systems, are developing rapidly, and battery management issues are gaining attention. In this application field, a battery system with a high capacity and high power in which numerous battery cells are connected in series and parallel is used. Therefore, research on a battery management system (BMS) to which various algorithms are applied for efficient use and safe operation of batteries is being conducted. In general, maintenance/replacement of multi-series/multiple parallel battery systems is only possible when there is no load current, or the entire system is shut down. However, if the circulating current generated by the voltage difference between the newly added battery and the existing battery pack is less than the allowable current of the system, the new battery can be connected while the system is running, which is called hot swapping. The circulating current generated during the hot-swap operation is determined by the battery’s state of charge (SOC), the parallel configuration of the battery system, temperature, aging, operating point, and differences in the load current. Therefore, since there is a limit to formulating a circulating current that changes in size according to these various conditions, this paper presents a circulating current estimation method, using an artificial neural network (ANN). The ANN model for estimating the hot-swap circulating current is designed for a 1S4P lithium battery pack system, consisting of one series and four parallel cells. The circulating current of the ANN model proposed in this paper is experimentally verified to be able to estimate the actual value within a 6% error range.


Author(s):  
Guang Xia ◽  
Yan Xia ◽  
Xiwen Tang ◽  
Linfeng Zhao ◽  
Baoqun Sun

Fluctuations in operation resistance during the operating process lead to reduced efficiency in tractor production. To address this problem, the project team independently developed and designed a new type of hydraulic mechanical continuously variable transmission (HMCVT). Based on introducing the mechanical structure and transmission principle of the HMCVT system, the priority of slip rate control and vehicle speed control is determined by classifying the slip rate. In the process of vehicle speed control, the driving mode of HMCVT system suitable for the current resistance state is determined by classifying the operation resistance. The speed change rule under HMT and HST modes is formulated with the goal of the highest production efficiency, and the displacement ratio adjustment surfaces under HMT and HST modes are determined. A sliding mode control algorithm based on feedforward compensation is proposed to address the problem that the oil pressure fluctuation has influences on the adjustment accuracy of hydraulic pump displacement. The simulation results of Simulink show that this algorithm can not only accurately follow the expected signal changes, but has better tracking stability than traditional PID control algorithm. The HMCVT system and speed control strategy models were built, and simulation results show that the speed control strategy can restrict the slip rate of driving wheels within the allowable range when load or road conditions change. When the tractor speed is lower than the lower limit of the high-efficiency speed range, the speed change law formulated in this paper can improve the tractor speed faster than the traditional rule, and effectively ensure the production efficiency. The research results are of great significance for improving tractor’s adaptability to complex and changeable working environment and promoting agricultural production efficiency.


2021 ◽  
Vol 1055 (1) ◽  
pp. 012153
Author(s):  
D Sarathkumar ◽  
M Srinivasan ◽  
Albert Alexander Stonier ◽  
Ravi Samikannu ◽  
Narasimha Rao Dasari ◽  
...  

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