EV Charging Ports

1. What is an EV Charging Port?

An electric vehicle (EV) charging port serves as the physical interface connecting the vehicle to charging equipment, acting as the critical conduit through which electrical energy flows from the power grid to the traction battery pack. A complete charging setup comprises two primary elements: the charging connector/gun (the plug end connected to the EV charger) and the vehicle inlet (the socket mounted onto the vehicle's body).

Electrified vehicles are typically equipped with two distinct charging ports—an alternating current (AC) port (commonly referred to as slow charging) and a direct current (DC) port (known as fast charging). Both differ noticeably in exterior design, pin count, and functionality: the AC port features a 7-pin layout, whereas the DC port utilises a 9-pin configuration.

2. Why Are Two Types of Charging Ports Needed?

An EV's traction battery pack operates as a direct current (DC) reservoir and can only accept DC electricity; conversely, the utility grid supplies alternating current (AC). Consequently, regardless of the charging method used, AC power must always be converted into DC—with the only key difference being  the location of the conversion unit:

• AC Charging (Slow Charging) : Once AC electricity enters the vehicle via the charging connector, the car's built-in On-Board Charger (OBC) converts it into DC. Due to the limited output capacity of the on-board charger (typically 3.3 kW to 22 kW), charging times are comparatively longer.

• DC Charging (Fast Charging) : The AC-to-DC conversion is handled externally by a dedicated DC fast charger, which feeds high-voltage DC electricity directly into the traction battery pack. Because DC fast chargers deliver substantially higher power outputs (typically 60 kW to 400 kW, reaching up to 800 kW), they charge significantly faster than AC chargers.

3. AC Charging Port (7-Pin)

The GB/T AC charging port features a 7-pin configuration, with each pin assigned a dedicated function:

In terms of electrical specifications, the GB/T AC interface supports up to three-phase 440V AC with a maximum current of 63A AC. Actual charging output varies depending on the electrical supply infrastructure: a 220V single-phase supply delivers between 2.2 kW and 7 kW, whereas a 380V three-phase supply provides between 11 kW and 40 kW.

4. DC Charging Port (9-Pin)

The GB/T DC charging port utilises a 9-pin layout. Compared to an AC port, the pin assignments and functions on a DC interface are substantially more intricate:

Regarding electrical ratings, the DC interface is rated for 750V / 1,000V / 1,500V DC. Under natural passive cooling, rated current levels span from 10A up to 300A across multiple tiers; with active cooling (liquid cooling), current capacity can reach 200A to 800A, enabling a theoretical maximum charging power of up to 1.2 MW.

5. The GB/T Standard Framework and Technical Evolution

China's new energy vehicle charging interface framework is built around the GB/T 20234 series of standards. Its technical progression clearly reflects ongoing engineering advancements and evolving market demands:

• 2006: The first charging interface standard was introduced; however, physical dimensions and pin definitions were not strictly specified, leading to widespread vehicle-to-charger incompatibility.

• 2011: Initial standardisation was established, defining the foundational architecture of 7-pin AC and 9-pin DC ports.

• 2015: The comprehensive GB/T 20234-2015 standard was released, achieving full charging port unification across the Chinese domestic market.

• 2023: The updated GB/T 20234.1-2023 and GB/T 20234.3-2023 (colloquially termed the "2015+" standard) were published. While retaining backward compatibility with existing sockets, these updates raised the maximum charging current from 250A to 800A and elevated the peak output to 800 kW, alongside introducing mandates for active liquid cooling and thermal monitoring.

• GB/T 20234.4-2023: A dedicated ultra-high-power DC charging standard capable of supporting up to 900 kW; however, it adopts an all-new physical interface and is incompatible with the standard 2023 edition.

Furthermore, China is spearheading the development of next-generation charging architecture via the ChaoJi standard. Entirely led by China with full proprietary intellectual property, this standard supports charging outputs of up to 900 kW while delivering significant improvements across mechanical safety, electrical insulation, electric shock mitigation, and thermal management. Having received unanimous approval from the IEC, the ChaoJi DC charging interface aims to offer unified compatibility across the four major global DC fast-charging protocols.

6. Mainstream Global Charging Port Standards

Worldwide charging standards remain ununified, with five primary protocols operating concurrently across different regions:

NACS (North American Charging Standard), developed by Tesla and opened to the wider industry in 2022, is rapidly establishing itself as the de facto benchmark in North America thanks to its high-power charging efficiency and extensive Supercharger network. Major automotive marques including Ford, GM, and Volkswagen have confirmed the adoption of NACS connectors on their production vehicles from 2024 onwards. The SAE has since codified this under the SAE J3400 standard, with the upgraded NACS protocol engineered to support 1,000V architectures and peak outputs of up to 1 MW (1,000 kW).

7. Built-In Safety Architecture

Modern EV charging interfaces incorporate multi-layered safety mechanisms:

• High-Voltage Interlock Loop (HVIL) : Connects all high-voltage connectors in series via a low-voltage monitoring circuit. If any component, such as the charging inlet, becomes unseated or loose, the low-voltage loop instantly disconnects, prompting the system to cut high-voltage power typically within 0.05 seconds.

• Electronic Locking Mechanism: When charging current exceeds 16A, the vehicle inlet must engage an electronic lock. Should the connection confirmation circuit disconnect, the vehicle is required to terminate charging and drop the current to 1A or less within 100 ms.

• Drive-Off Interlock (Drive Inhibitor): While the vehicle is plugged in and actively charging, the high-voltage management system prevents the powertrain from engaging, eliminating the risk of accidental drive-away cable damage.

• Poka-Yoke (Foolproof Keying): Both AC and DC charging connectors and vehicle inlets feature strict geometric keying, ensuring they can only be inserted in the single, correct orientation.

Summary

The charging port serves as the vital nexus connecting electric vehicles to modern power infrastructure, and its degree of standardisation directly dictates consumer convenience and EV industry scalability. China has established a highly unified domestic market via the GB/T 20234 ecosystem and continues to shape the future of global charging technology through the "2015+" standard and the rollout of the next-generation ChaoJi architecture. From 7-pin AC to 9-pin DC, 250A to 800A, and conventional unidirectional charging to V2X bidirectional capability, the ongoing evolution of charging interfaces perfectly exemplifies the rapid advancement of the global new energy vehicle landscape.