Electric vehicle charging methods
The charging methods for electric vehicles mainly include conventional AC charging, fast DC charging, wireless charging, mobile charging, and battery replacement charging.
1. Conventional AC charging method
This charging method uses the traditional charging method of constant voltage and constant current to charge electric vehicles, that is, it uses the portable EV charger equipped with the vehicle for charging, and can use household power supply or dedicated charging station power supply. It’s what we use in passenger cars now,on-board chargers and home wall-mounted EV chargers. The charging current is as small as 16-32A, and the current can be direct current or two-phase alternating current or three-phase alternating current. Therefore, the charging time is 5 to 8 hours depending on the capacity of the battery pack.
The shortcomings of the AC charging mode are very obvious. The charging time is long, but its charging requirements are not high, and the charger and installation costs are low. It can make full use of low power periods for charging and reduce charging costs. The more important advantage is that it can Deeply charge the battery, improve battery charging and discharging efficiency, and extend battery life. Because the charging time is long, it can greatly satisfy vehicles that operate during the day and rest at night.
2. Fast DC charging method
As the name suggests, this is a charging method that can quickly fully charge the battery. It uses a large current to directly charge the battery through an off-board charger, so that the battery can be charged to about 80% of the power in a short time, so it is also called emergency charging. The representative of the fast charging mode is the Tesla Super Charging Station. The current and voltage of the fast charging mode are 150~400A and 200~750V, and the charging power is greater than 50kW. This method is mostly DC power supply. The charger on the ground has high power and a wide range of output current and voltage.
3. Wireless charging method
Wireless charging mode does not require the transmission of energy through cables, but uses electromagnetic induction, electric field coupling, magnetic resonance and radio waves to transmit energy, as shown in Figure 5-4. To use wireless charging mode, you first need to install an on-board induction charger in the car. There is no mechanical link between the power receiving part and the power supply part of the vehicle, but the power receiving body and the power supply body need to be connected more accurately.
Due to limitations in technological maturity and infrastructure, wireless charging facilities and equipment are currently unable to be mass-produced and applied. The mainstream wireless charging technology in the industry mainly uses electromagnetic induction and magnetic resonance to transfer electric energy. The magnetic resonance method has higher charging efficiency and lower electromagnetic radiation intensity. It is less intense than when talking on a mobile phone. More importantly, the power transmitting coil and the power receiving coil There is no need to be perfectly aligned, something that electromagnetic induction cannot achieve.
The future application prospects of wireless charging mode are immeasurable. In the future, it will be possible to charge while traveling. The electric energy may come from the power supply system of the road pavement, or from the electromagnetic wave energy received by the car.
4. Mobile charging method
This is the most ideal charging method. The main way is to charge the car while the car is cruising. Customers don’t have to look for charging piles and spend time charging. This charging method requires a MAC system and is buried under a section of road in advance, that is, the charging area. Both contact and induction MAC can be implemented. This charging method costs a lot and is still in the theoretical research stage, but it has broad prospects.
5. Replace the battery
In addition to conventional direct charging of the vehicle, the battery can also be charged by replacing the power battery. That is, when the power battery is exhausted, replace the battery pack with low power with a fully charged battery pack. There are three ways to replace the battery pack from the vehicle: manual, semi-automatic and robotic.
The replacement battery integrates the advantages of conventional charging mode and fast charging mode. The biggest limitation of battery replacement charging mode is that major manufacturers need to unify battery specifications, sizes and other standards, and cannot guarantee the consistent performance of each battery pack, thus restricting its development.
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