Charging Control Strategy Research Articles

Analog One-Cycle Control Strategy for Stable Battery Charging in Photovoltaic Systems

The growing adoption of photovoltaic systems for direct electricity generation from solar radiation has underscored the importance of efficient energy storage solutions. Batteries are the predominant method for storing energy from photovoltaic systems, especially for applications such as electric vehicle (EV) charging. However, these systems face significant challenges, particularly regarding battery longevity, as fluctuations in solar irradiation can lead to harmful voltage spikes. This paper introduces an Analog One-Cycle Control (OCC) strategy designed to mitigate these issues by stabilizing the battery voltage against varying input voltages. The proposed control scheme aims to enhance battery life by preventing damage caused by voltage overshoots. Experimental results demonstrate the effectiveness of the OCC strategy in maintaining steady-state conditions and optimizing power management.

A charge and discharge control strategy of gravity energy storage system for peak load Cutting

Gravity energy storage is a type of energy storage method that utilizes gravitational potential energy to store energy. In recent years, it has been widely concerned by scholars and enterprises at home and abroad for its unique advantages. From the perspective of long-term profit, the economic analysis of the gravity energy storage system is essential. In previous studies, only some specific economic models are available for describing the gravity energy storage system. This article proposes a revenue model for the gravity energy storage system first. Then, suggest a method for operating and scheduling a decentralized slope-based gravity energy storage system based on peak valley electricity prices. This method aligns with the current business model of using user-side energy storage to participate in power system auxiliary services. Last, verify the feasibility of the process through analysis. This study will make a beneficial attempt for the market promotion and application of gravity energy storage.

Study on charge and discharge control strategy of improved PSO for EV

In view of the negative influence of electric vehicle (EV) random charging on power grid load stability and charging cost of users, on the premise of guaranteeing users' travel demand, in this paper, an improved PSO model is proposed with the objective function of optimizing the daily load variance of the power grid and minimizing the charge cost of the vehicle owner. In this model, chaotic mapping is used to initialize the position of particles so that the particles are uniformly distributed in space and the diversity of particle solutions is increased, based on the global search ability and local search ability of the improved algorithm, combined with the analysis of a numerical example, the results show that the improved multi-objective PSO algorithm converges quickly and can jump out of the local optimum, better multi-objective optimization to reduce the peak-valley load difference and charging costs.

Optimal Bivariate Control Strategy of Multistage Constant Current Charging for IPT-Based Wireless Electric Vehicle Charging

Optimal Bivariate Control Strategy of Multistage Constant Current Charging for IPT-Based Wireless Electric Vehicle Charging

Research on Energy Storage Flywheel Motor Drive Control Technology

Currently there is a way to use for energy storage: batteries for chemical energy storage, super for electric field energy storage, and flywheel batteries for mechanical energy storage. Flywheel energy storage has the advantages of high energy storage density, high efficiency, short charging time, no pollution, wide applicability, no noise, long service life, easy maintenance and continuous operation. Recently the most promising and competitive new energy storage technology - flywheel energy storage technology, relative to other forms of energy storage, by domestic and foreign experts unanimously optimistic. This paper will focus on the composition and operation principle of flywheel energy storage system, the classification of drive control strategy, charging control strategy, discharge control strategy and other aspects.

Researches on Operation Optimization of Charging Device Participating in Demand Response of Power Grid

The application of electric vehicles has been an important mean to solve crisis of oil supplies and environment protection pressure. The number of charging devices has increased rapidly due to the orientation of policy and market in recent years. As a result, the load peak-to-valley difference will be aggravated and the electricity cost of residents will be increased. The purpose of the paper is researching the path to achieve the demand response with orderly charging of electric vehicles when a large number of electric vehicles are connected to the grid. Firstly, technological development trends of electric vehicles are analyzed. Secondly, a scheme that can uniformly manage and regulate load resources is designed by considering the charging needs of users in a comprehensive way. The core devices such as energy controller and energy router are applied in the scheme. Thirdly, a series of experiments are conducted in a residential district with 660 households and 24 charging piles in Beijing. Finally, the results indicate that the load peak-trough difference of the residential district has reduced by 58% if all of users choose to participate in demand response based on the control strategy of orderly charging.

Soft-switching dual active bridge converter-based bidirectional on-board charger for electric vehicles under vehicle-to-grid and grid-to-vehicle control optimization

Electric vehicles (EVs) are rapidly replacing conventional fuel vehicles, offering powerful, emission-free performance. This paper introduces an innovative three-phase bidirectional charger for grid-to-vehicle (G2V) and vehicle-to-grid (V2G) applications, strengthening the connection between EVs and the power grid. The charger employs a two-stage power conversion approach with advanced converters and a simplified dq-based charging control strategy. An efficient AC-DC converter facilitates smooth transitions between modes, responding to grid directives for active and reactive power. A soft-switching dual active bridge (SS-DAB) DC-DC converter optimally interfaces with the EV battery pack, while dual active LCL filters suppress harmonics, enhancing system performance. Simulated results confirm the charger’s effectiveness in a 3.5-kW prototype using MATLAB/Simulink. The proposed SS-DAB converter-based bidirectional on-board charger introduces a groundbreaking unified Voltage Source Converter (VSC) control approach, enabling efficient power transfer in both vehicle-to-grid (V2G) and grid-to-vehicle (G2V) modes. This innovation ensures rapid dynamic response, exceptional steady-state performance, and robustness against grid demand changes, optimizing EV integration.

Soft-switching dual Active Bridge Converter-based Bidirectional On-Board Charger for Electric Vehicles under Vehicle-to-Grid and Grid-to-Vehicle Control Optimization

Electric Vehicles (EVs) are rapidly replacing conventional fuel vehicles, offering powerful, emission-free performance. This paper introduces an innovative three-phase bidirectional charger for Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) applications, strengthening the connection between EVs and the power grid. The charger employs a two-stage power conversion approach with advanced converters and a simplified dq-based charging control strategy. An efficient AC-DC converter facilitates smooth transitions between modes, responding to grid directives for active and reactive power. A Soft Switching Dual Active Bridge (SS-DAB) DC-DC converter optimally interfaces with the EV battery pack, while dual active LCL filters suppress harmonics, enhancing system performance. Simulated results confirm the charger’s effectiveness in a 3.5kW prototype using MATLAB/Simulink.

AI enabled fast charging of lithium-ion batteries of electric vehicles during their life cycle: review, challenges and perspectives

This review presents a thorough investigation of factors affecting fast charging, battery modeling, key state estimation and fast charging control strategies and provides a forward-looking perspective on AI enabled fast charging technology of LIBs.

An efficient hierarchical electric vehicle charging control strategy

AbstractElectric vehicle (EV) has emerged as a crucial component in addressing both energy and environmental problems, and has become an essential part of nowadays' intelligent transportation systems. However, the charging demands of large amounts of EVs can put substantial pressure on power grid systems and cause potential grid congestion problems. In this article, we propose a hierarchical EV charging control strategy that considers the network‐wide communication overheads, computational complexity, total energy cost, EV user preferences, and data privacy protection. The hierarchical charging structure contains two phases, that is, a centralized control for EV aggregators and a distributed control for EVs within an aggregator. We prove that the centralized control with the objective to minimize the total energy cost of the power system constitutes a convex quadratic programming problem. Then a unique global optimum for the energy consumption profiles of EV aggregators can be achieved. The distributed charging control for EVs within an aggregator is studied using a generalized Nash equilibrium problem (GNEP). We show that the solution of the GNEP can be obtained via a variational inequality. Then the Solodov and Svaiter hyperplane projection method is employed to iteratively approach the variational equilibrium while ensuring the protection of EV users' data privacy. Extensive simulation studies are conducted to verify the correctness and effectiveness of our proposed hierarchical charging control algorithm for EVs.

Analysis and mitigation of the impact of electric vehicle charging on service disruption of distribution transformers

The transition to electric mobility could overload distribution transformers to unprecedented levels. Sustained overloads produce excessive heat within the transformer and hasten insulation deterioration. As EV deployment rises and the severity of overloads increases, the focus shifts from long-term effects that reduce transformer life to more immediate impacts that can disrupt normal functioning. The latter typically manifest as the blowing of protection fuse, the triggering of pressure relief device, or the breakdown of winding insulation, each of which could result in transformer outage. The transformer’s vulnerability can be monitored in terms of its apparent power flow, top-oil temperature and hottest-spot temperature. The IEEE C57.91 standard specifies the permissible range for these parameters, beyond which the transformer operation could get interrupted. A study to determine the range of EV penetration that can be accommodated by a distribution transformer without any discontinuity in its operation is presented in this paper. The non-linear nature of EV charging is incorporated in the analysis to account for the effect of higher-order harmonics on the transformer’s internal temperature. The effectiveness of a controlled charging strategy, which seeks to regulate transformer loading by minimizing its variance, in preventing service disruption is also validated in this simulation study.

A SOC Correction Method Based on Unsynchronized Full Charge and Discharge Control Strategy in Multi-Branch Battery System

LiFePO4 batteries exhibit voltage plateau and voltage hysteresis characteristics during charging and discharging processes; however, the estimation of state-of-charge relies on voltage detection. Thus, the estimation accuracy of SOC is low in a traditional method. In this paper, a full charge and discharge SOC correction method is proposed; i.e., the SOC is corrected to 100% when the battery is fully charged and to 0% when fully discharged, and the actual usable capacity is corrected using the fully discharged capacity after being fully charged. Thereby, the cumulative error of the ampere-hour integration method is dynamically corrected. In engineering applications, however, the battery systems do not always undergo full charge and discharge cycling due to the operating conditions. By making full use of the distributed control characteristics of the multi-branch topology battery system, the present work proposes an optimized system control strategy to realize the unsynchronized full charge and discharge cluster by cluster, which extends the application of the full charge and discharge SOC correction method. The experimental results verify the accuracy of the proposed SOC correction method and the feasibility of the control strategy. A more reliable and efficient battery management scheme is provided for LFP battery system, which has high practical value in engineering.

Mobility‐aware optimal trade planning and mean field game‐based decentralized charging control for large‐scale electric vehicles

AbstractThe uncertainty mobility characteristics of electric vehicles (EVs) are a key factor that influence the charging station trade income with the power grid. In this paper, a hierarchical energy management strategy is proposed for charging stations when large‐scale EVs are considered. The traveling and parking mobility characteristics of EVs are first extracted by analyzing historical real‐world traveling data. Then, a day‐ahead power trade planning strategy between the grid and charging station to maximize incomes is developed by solving a mixed‐integer linear programming problem. Furthermore, based on EV mobility characteristics, clusters are generated to classify different parking behaviors, where a mean field game‐based decentralized charging control scheme for individual EVs in each cluster is employed. The target of the proposed optimal charging controller is to guarantee the charging power tracking performance and the power demand of individual EV at the terminal time for subsequent travel. Finally, simulations on MATLAB/Simulink platform are conducted to show the effectiveness of the proposed hierarchical energy management strategy.

Adaptive Constant-Current/Constant-Voltage Charging of a Battery Cell Based on Cell Open-Circuit Voltage Estimation

This paper presents the novel design of a constant-current/constant-voltage charging control strategy for a battery cell. The proposed control system represents an extension of the conventional constant-current/constant-voltage charging based on the so-called cascade control system arrangement with the adaptation of the battery charging current based on the open-circuit voltage parameter estimation. The proposed control strategy features two feedback controllers of the proportional-integral type responsible for: (i) controlling the battery open-circuit voltage towards its fully charged state, and (ii) simultaneously limiting the battery terminal voltage to avoid the battery terminal voltage constraint violation. The open-circuit voltage on-line estimation is implemented by using the system reference adaptive model approach to estimate the linear time-invariant battery equivalent circuit model parameters, whose asymptotic convergence is guaranteed according to Lyapunov stability theory. The proposed concept of the battery charging control is verified by means of simulations using the experimentally obtained model of a lithium iron phosphate battery cell, and it is also compared to other charging methods with respect to charging speed-up potential compared to conventional charging. The proposed method, which can be easily extended to conventional chargers, results in 23.9% faster charging compared to conventional charging, thus representing an inexpensive and straightforward upgrade to conventional battery charging systems.

Integration of EVs through RES with Controlled Interfacing

Abstract Electric cars have a lot of promise in future energy markets as a manageable load. A popular vehicle-to-grid control interface, which enables the aggregation of the charging mechanism for energy management in the distribution grid, is one of the most significant road blocks to realize this opportunity. Understanding the ecology of electric transportation and integrating it in local communities to alleviate the energy shortage at peak hours is very complicated. In this research paper, recent standardization initiatives aimed at overcoming obstacles such as the integration of electric cars into smart grids are discussed. A charge control scheme focused on vehicle-to-grid connectivity is implemented. It is observed that the rise of environmentally sustainable energy sources, such as photovoltaic (PV) and wind energy, is straining the power network and their infrequent power generation is causing problems in power system operation, regulation and planning. The introduction of electric vehicles (EVs) into the electricity grid has been proposed to overcome grid load variations. Finally, the article discusses the incorporation of renewable energy sources and latest potential solutions involving electric vehicles.

Novel approach for liquid-heating lithium-ion battery pack to shorten low temperature charge time

The charging time for Li-ion power battery in hybrid electric vehicles (HEVs) and pure electric vehicles (EVs) is elongated at low temperature compared to that at the room temperature, which will deteriorate the customer using experience. Therefore, shortening the low-temperature charging time of battery is the critical technology to promote the popularization of electric vehicles. Many techniques have been proposed to shorten the low-temperature charging time, but these technologies often lead to problems such as the increase of vehicle energy consumption, the high temperature of the battery pack system (BPS) at the end of charging and the poor BPS temperature uniformity during charging. To tackle these problems, this paper proposes an optimization simulation model for charging control strategy combined with thermal model (SCCS-ThM) and BPS offline parameters based on a liquid heating thermal management system (LHTMS). The BPS offline parameters determine the charging power threshold under different ambient temperature and the different state of capacity (SoC). The temperature rise and the temperature differences of the BPS during charging are calculated with the thermal model. The optimization model obtains the optimal charging strategy by simulating the potential feasible charging strategies. The battery pack charge time is reduced by introducing a pre-heating stage prior to charging. The pre-heating period which minimizes overall charge time, including the pre-heating time, is determined using the thermal model. The experimental results show that for an initial battery pack temperature of −10 °C, overall charge time is minimized by starting to charge after the battery pack has been heated to 1 °C. With the same charging energy, the optimal charging strategy shortens the charging time by 16 % and reduces battery coolant heater energy consumption by 15 %. Besides, the maximum temperature at the end of charging and the maximum temperature difference during the whole charging process are 36 °C and 6 °C respectively, which are better than the original charging strategy.

An adaptive charge control strategy for participation of neighbourhood battery energy storage systems in frequency stability

Neighbourhood Battery Energy Storage System (N-BESS) is a new scale of energy storage that is expected to have a potential role in modern power systems stability. In the literature, there is a lack of studies that proposed a smart engagement of N-BESS in the frequency stability. In this paper, an adaptive charge control strategy for the N-BESS has been proposed to enhance the frequency stability while maintaining a fair State-of-Charge (SOC) levels for N-BESS. Also, a collaborative framework for large-scale Battery Energy Storage System (L-BESS) with N-BESS has been introduced, in which the N-BESS play an auxiliary role in frequency stability. In this study, a number of system uncertainties, including N-BESS SOC, load consumption, wind farm generation, and contingency size and location, have been considered. The simulation has been carried out in the Simplified 14-Generator Model of the South East Australian Power System over one-year simulation using DIgSILENT/PowerFactory software and Python interface. The results have demonstrated that a higher SOC levels of N-BESS under the proposed strategy have been maintained compared to that of the conventional strategy. Moreover, when the L-BESS collaborated with the N-BESS under the proposed framework, the best frequency stability with highest SOC levels of N-BESS have been obtained; at the same time less discharged power by the L-BESS was noted compared to that when the L-BESS participated individually which indicated that a smaller L-BESS size would be required if it collaborated with N-BESS in frequency stability service.

State-Flow Control Based Multistage Constant-Current Battery Charger for Electric Two-Wheeler

Battery charging is a greater challenge in the emerging electric vehicle domain. A newer multistage constant-current (MSCC) charging technique encompassing state-flow control tool-based design is implemented for charging the battery of an electric two-wheeler. MSCC method allows for faster charging and reduced battery degradation per charge. The designed controller incorporates line current power factor correction, thereby limiting the total harmonic distortion (THD) in line current and reactive power. The control strategy for battery charging has been developed using the state flow chart approach for implementing MSCC. The model has been formulated and implemented in MATLAB/Simulink. The proposed control monitors the state-of-charge (SOC) of the battery, age, and thermal behavior due to the charging strategy. The results show that the proposed charging technique with a state flow control approach gives effective and efficient output with reduced THD. Simulation results disclose that the desired parameters are controllable, stable, and effective within the operational limits.

A Study and Implementation of Inductive Power Transfer System Using Hybrid Control Strategy for CC-CV Battery Charging

In this paper, a hybrid control strategy is studied and implemented on an Inductive Power Transfer (IPT) system to simultaneously realize zero-voltage switching (ZVS) and constant current (CC) and constant voltage (CV) battery charging. A steady-state analysis of pulse frequency modulation was conducted, based on the characteristic of voltage gain versus switching frequency, and CC and CV charging modes were promised. The ZVS of the inverter was obtained by satisfying the minimum requirement of full discharge of the junction capacitor on the MOSFETs using a commutation current during the dead-time interval. Two control degrees of freedom are needed to realize the two control targets. This hybrid control strategy adopts a self-oscillating (SO) control to achieve ZVS and phase shift (PS) control and a constant output for the series–series (SS)-compensated IPT system. To validate the hybrid control strategy, a 1.6 kW prototype with 360–440 V input voltage and 250–400 V output voltage was built and the experimental results show that the peak efficiency can reach 96.1%. Compared with the conventional variable frequency (VF) control, the hybrid control method proves that an additional control variable can fulfill the control target in a more flexible manner, which makes the switching frequency close to the resonant frequency during the charging process, minimizing the reactive current in the resonant tank and improving system efficiency.

Modeling of bidirectional electric vehicle charger for grid ancillary services

Abstract This paper presents the evolution of bidirectional electric vehicle charger for G2V (i.e., Grid-to-Vehicle) and V2G (i.e., Vehicle-to-Grid) utility. Electric vehicle are growing day by day in the area of transportation. As more electric vehicles hit the road to maintain the need for charging, bidirectional charging becomes essential. Bidirectional charging in electrical vehicles facilitates users to either make energy flow to the vehicle or flow from the vehicle. The proposed design allows users to make economic gains from electric vehicle with other exciting advantages. Particularly unidirectional charging solution restricts the user to use energy for charging only applications whereas, this paper proposed a control strategy for bidirectional charging of electric vehicles. Hence electric vehicles could be potentially used as a source during an emergency like power outages, grid failure, or whenever there is an excess load on grid and user needs more energy. Additionally, this paper uses an integration of buck and boost converter to develop a bidirectional vehicle charger. The performance of bidirectional converter with control algorithm is verified by simulation on MATLAB Simulink.