Technical Principles and Power Classification
The core function of an AC charging station is to convert mains power (single-phase 220V or three-phase 380V) into a charging signal that the vehicle can recognize. Its power is determined by voltage, current, and the number of phases. Based on output capacity, AC charging stations can be divided into three categories:
Low-power type (3.5kW-7kW): Primarily powered by single-phase 220V, with a current typically of 16A or 32A. Suitable for homes or small parking lots. For example, a 7kW AC charging station can fully charge an electric vehicle with a range of 400km (assuming a battery capacity of 60kWh) in 8 hours, covering daily commuting needs.
Medium-power type (11kW-15kW): Uses three-phase 380V power, with a current reaching 16A or 32A. Commonly found in commercial parking lots or public charging stations. This type of charging station can shorten charging time to 4-6 hours, suitable for short to medium distance travel.
High-power type (22kW): Requires three-phase 380V power supply with a current of 32A or higher. Currently commonly found in high-end models or dedicated fast-charging stations. A 22kW charging pile can charge a 60kWh battery in 3 hours, but the vehicle must support a three-phase charging interface (such as some Tesla models).
Industry Standards and Limiting Factors
Grid Power Supply Capacity: High-power charging piles require transformers and wiring of corresponding capacity. For example, a 22kW charging pile requires at least 10mm² cable. Excessive grid load may cause voltage fluctuations or tripping.
Vehicle Compatibility: The on-board charger (OBC) of an electric vehicle determines its maximum receiving power. Some older models only support 3.3kW AC charging; even with a 22kW charging pile, the actual power is still limited by the vehicle.
Communication Protocol: AC charging piles communicate with vehicles via protocols such as GB/T 18487 or CCS to dynamically adjust the output power. Protocol incompatibility may lead to charging interruptions or power degradation.
Application Scenarios and Selection Recommendations
Home Scenarios: Prioritize 7kW single-phase charging piles to balance cost and efficiency. If grid capacity allows (e.g., in villas or detached houses), upgrade to 11kW three-phase charging piles to reserve space for future models.
Public Scenarios: Commercial parking lots are recommended to deploy 11kW-15kW charging piles to balance user demand and return on investment. Highway service areas or large charging stations can deploy a small number of 22kW charging piles to meet rapid charging needs.
Special Environments: In low-temperature areas, choose charging piles with heating functions to prevent decreased battery activity and reduced charging efficiency; in high-humidity environments, IP55 or higher protection ratings are required to ensure equipment safety.
