Evolution of Electric Vehicle Charging Equipment Technology: Grid Compatibility and Efficiency Optimization from Slow Charging to Supercharging

Keywords: electric vehicle charging equipment, slow charging, fast charging, overcharging, grid compatibility

abstract

Charging efficiency and grid compatibility are key factors in the popularization of electric vehicles. This article analyzes the technological evolution and grid coordination solutions from charging protocols, power semiconductors to V2G technology.

2.1 Limitations of Traditional Slow Charging Technology

Slow charging speed: It takes 7 hours to fully charge a 50kWh battery with a 7kW AC charging station, which cannot meet users' fast energy replenishment needs.

Large impact on the power grid: Disorderly charging may lead to local power grid overload (such as a 300% increase in load during peak charging periods in a residential area in Beijing).

2.2 Breakthroughs in Fast Charging and Supercharging Technologies

Liquid cooled high-power charging: Huawei's 600kW supercharging station uses a liquid cooled gun cable with a current of 1000A. It can charge for 5 minutes and has a range of 200 kilometers, but it needs to solve cable heating (temperature<60 ℃) and electromagnetic interference (EMI<50dB μ V).

Application of SiC power devices: By using Cree 1200V SiC MOSFET, the efficiency of the charging module is increased from 95% to 97%, and the loss is reduced by 40%.

2.3 Charging Protocol and Standardization

CCS（Combined Charging System）： The DC fast charging standard dominated by Europe and America supports a maximum power of 350kW and is compatible with AC/DC dual-mode.

GB/T 20234.3： The Chinese national standard requires the temperature sensor of the charging gun to have an accuracy of ± 1 ℃ and an insulation resistance greater than 100M Ω to ensure charging safety.

2.4 Grid Collaboration and V2G Technology

Ordered charging scheduling: By using AI algorithms to predict user charging demand, the fluctuation of grid load can be reduced by 50% (such as Tesla Powerwall home energy storage system).

V2G（Vehicle-to-Grid）： The BYD Han EV achieves bidirectional charging and discharging, with a discharge power of 6.6kW, which can supply power to households for 4 hours and participate in grid peak shaving with a profit of 0.5 yuan/kWh.

2.5 Wireless Charging and Automation

Magnetic resonance wireless charging: WiTricity technology achieves 11kW wireless charging with an efficiency of 93% and a positioning accuracy of ± 10cm, suitable for shared electric vehicles.

Robot automatic gun insertion: NIO's second replacement power station uses a six axis robot, with a success rate of 99.9% for gun insertion and a shortened battery replacement time to 3 minutes.

conclusion

Charging technology needs to shift from "one-way energy replenishment" to "grid synergy". By integrating overcharging, V2G, and wireless charging, an efficient and flexible charging network can be constructed.