Today’s electric vehicles (EVs) are slowly taking over the automotive industry and will replace traditional gasoline vehicles. The driver of this change is the increasing need to conserve fossil fuels and protect the environment.
Currently, conventional gasoline vehicles are responsible for 17% of total greenhouse gas emissions. Electric vehicles not only help reduce the use of fossil fuels by harnessing renewable energy, but also help protect the environment as they emit almost no emissions. They provide high efficiency and clean energy, thus paving the way for the growing electric vehicle industry.
While EVs are a great option, it’s important to consider potential hurdles they face, such as limited driving range and longer charging times. The lower cruising range means a limitation in driving distance compared to conventional vehicles. This poses a major problem for the growing number of customers, as current infrastructure and grids are insufficient to keep up with this surge.
Even if all gas stations were replaced with EV charging stations, the problem would only be partially solved. While refueling takes about a few minutes, the wait time for charging an EV can vary from 15 minutes to several hours, depending on the technology and power level of the charger. As a solution, charging times need to be drastically reduced.
Battery optimization for fast charging
Since the battery is a major component of a fast charging system, understanding how the battery will perform under fast charging is important to improve efficiency. The US National Renewable Energy Laboratory (NREL) has given some electrochemical models of lithium-ion batteries to optimize electrode and battery design.
These advanced electrochemical models accelerate the development of next-generation batteries that will be able to deliver fast charging, high energy, low cost and extended lifetime.
The macroscopic homogeneous model tests the movement of lithium in the battery and analyzes its reaction rate through the thickness of the electrode. These models are used to express rate limits and identify new ways to achieve fast charging.
The microstructural model is based on the three-dimensional geometry of the active material particles. They provide information on how the particles are packed into the electrodes. The microstructural model describes the distance the ions must travel and the obstacles they face as they move around the electrodes.
A degradation model is used to measure how degradation methods such as lithium leaching or cathode cracking affect the overall performance of the battery. They compare various reactions in batteries to evaluate new battery materials for improved performance.
Circuits for increased power density
This circuit describes the GaN active-clamp phase-shifted full-bridge architecture, a DC/DC converter capable of transferring energy from a 400V vehicle traction battery in an EV to power a 12V electrical system. Its soft switching, combined with GaN transistors, enables significantly higher switching frequencies up to 500kHz. This in turn helps to increase power density.
In this circuit, low conduction and low switching energy are achieved by using silicon carbide (SiC) or GaN transistors which are far superior to silicon devices. The circuit is also capable of delivering significantly increased levels of power density while maintaining the existing high efficiency. Its prototype achieved an efficiency of over 95% and a power density of 12.5kW/L.
Enhanced fast charging mechanism
While DC fast chargers can significantly reduce charging times, DC charging stations are very expensive to install. In addition, they put pressure on the grid due to high electricity demand.
One potential solution is to integrate DC chargers with battery energy storage systems (BESS). The purpose of integrating the BESS with a DC charger is to be able to supply power from the grid and battery storage system. When the EV is not connected, the BESS charges and stores energy from the grid. Then, once the EV is connected, it receives power from both the grid and the battery system to withstand fast charging while reducing the load on the grid.
Considering that one of the main problems of DC fast charging is the short distance, there is an urgent need to shorten the charging time and increase the compatible infrastructure. Therefore, the integration of BESS with DC chargers significantly reduces grid infrastructure costs. In addition, the development of new technologies for batteries, large-scale production (especially Li-ion batteries), and the reduction of battery costs have made the implementation of stationary BESSs more feasible.
Also read: What is energy storage BMS
Relationship between fast charging and environmental protection
On the one hand, fast charging can reduce endurance anxiety, reduce the capacity of the power battery, reduce the weight of the vehicle and reduce the power consumption per kilometer, which can achieve both energy saving and environmental protection.
On the another hand, fast charging will reduce charging efficiency, and excess electric energy will become useless heat. In addition, it will accelerate battery aging, reduce battery life, accelerate the formation of lithium dendrites, and cause the risk of spontaneous combustion. In addition, super fast charging will greatly increase the load on the power grid, requiring the use of a lot of social resources to build infrastructure.
Therefore, fast charging cannot directly refer to environmental protection, it has two sides of environmental protection and non-environmental protection.
Many battery manufacturers previously speculated on the environmental protection characteristics of V2G reverse charging. In fact, this solution that consumes the cycle life of power batteries is not environmentally friendly at all, because heavy pollution will be generated during the production and recycling of power batteries. There are basically no winners in grid energy storage solutions.
The biggest weakness of electric vehicles is that the bottleneck of battery technology cannot be broken through, and the habit of using cars (refueling in 3 minutes) developed by the automobile society for more than 100 years is not compatible with it. Another possible solution. EV manufacture companies that talk about the future of electric vehicles without energy density and fast charging are basically untrustworthy.