Abstract
Charging performance affects the commercial application of electric vehicles (EVs) significantly. This paper presents an optimal charging strategy for Li-ion batteries based on the voltage-based multistage constant current (VMCC) charging strategy. In order to satisfy the different charging demands of the EV users for charging time, charged capacity and energy loss, the multi-objective particle swarm optimization (MOPSO) algorithm is employed and the influences of charging stage number, charging cut-off voltage and weight factors of different charging goals are analyzed. Comparison experiments of the proposed charging strategy and the traditional normal and fast charging strategies are carried out. The experimental results demonstrate that the traditional normal and fast charging strategies can only satisfy a small range of EV users’ charging demand well while the proposed charging strategy can satisfy the whole range of the charging demand well. The relative increase in charging performance of the proposed charging strategy can reach more than 80% when compared to the normal and fast charging dependently.
Highlights
Electric vehicles have been the new development point of the motor industry because of the advantages of zero pollution and high energy efficiency [1,2,3]
In a constant current constant voltage (CC-CV) charging process, the battery is first charged with constant current, and when the battery voltage reaches the cut-off value, the battery is charged with constant voltage
Optimizations of three, five and seven charging stages are conducted to analyze the influence of Optimizations of three, five and seven charging stages are conducted to analyze the influence of charging stage numbers
Summary
Electric vehicles have been the new development point of the motor industry because of the advantages of zero pollution and high energy efficiency [1,2,3]. Li-ion batteries with high energy density, good life cycle performance, and low self-discharge rate [4,5,6,7] are being more widely used in electric vehicles. The Li-ion battery charging strategy has become the bottleneck of their application, due to the slow charging speed and uncertain effects on battery life. Li-ion battery charging optimization technology has become one of the central difficult issues [8]. In a CC-CV charging process, the battery is first charged with constant current, and when the battery voltage reaches the cut-off value, the battery is charged with constant voltage. The constant voltage process extends the charging time. Gao [12] proposed a boundary-curve based optimum charging current strategy. The temperature rise and polarization voltage were used to obtain the boundary curves during the charging process. The charging time was Energies 2017, 10, 709; doi:10.3390/en10050709 www.mdpi.com/journal/energies decreased decreasedand andbattery batterycapacity capacity was was increased
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