Control Strategies for Smart Charging of Electric Vehicles from a Grid Perspective: A Review

Electric vehicles have emerged as an alternative way to reduce fossil fuel consumption, which is the cause of increasing environmental, economical and geopolitical problems. This paper reviews the strategies for charging electric vehicles smartly from the viewpoint of the grid. These strategies are classified into three categories. The strategies at the component level discuss the necessary aspects of batteries, their charging methods, and chargers for smart charging purposes. The strategies on the system level are discussed under the heads of unidirectional and bidirectional power flow strategies. Unidirectional power flow strategies manage the power flow from the grid to electric vehicles for their charging. The bidirectional power flow strategies, apart from charging the electric vehicles, also use their battery storage for grid support. Also, the strategies that can be deployed at the operational level are discussed. These strategies, on the one hand, tend to alleviate the stressful impacts of increasing the load of charging the electric vehicles on the grid, and on the other hand, use the energy storage capability of the electric vehicles for grid support.