Concurrent and Non-Concurrent Pulse-Current Charging for Electric Vehicle Lithium-Ion Batteries

By the end of 2030, a large electric vehicle (EV) adoption on the roads will overburden the power grid for EV charging. Therefore, in order to divert EV loads from the grid, a grid-free EV battery charger is proposed in this article. The charger consists of a photovoltaic (PV) panel as a source with parallel sets of four-switch-buck-boost (FSBB) converters and Lithium-ion (Li-ion) batteries. The main theme of the control method is to harvest maximum PV power while delivering energy to the battery with contemplating battery life extension. In order to fulfill these two control objectives, an accurate 4-point PV-MPPT combined with pulse current battery charging methods are employed. In a simulation study of the parallel configuration with a 250 W PV panel and two 48 V Li-ion batteries, the concurrent operation of converters (COC) and non-concurrent operation of converters (NOC) are examined. In the COC pulse charging, two batteries simultaneously receive half PV power, whilst in the NOC pulse charging, two batteries alternately receive full PV power. It has been established that the NOC delivers continuous PV power and charges both batteries at a faster rate than the COC. Further, the simulation analysis is illustrated with a 20 kW PV parking shed for workplace for charging ten e-cars' batteries possessing different initial SoCs in NOC. Finally, an experimental proof of the concept is validated through a laboratory-scale hardware design of a 250 W PV panel charging two 48 V Li-ion batteries.