As the use of battery electric vehicles becomes more widespread and charging demand grows, the market is placing increasingly stringent requirements on vehicle charging safety and convenience. Convenient, safe, and fast charging has become a universal market expectation for vehicles.

　　1. Electric Vehicle Supply Equipment (EVSE)

　　Refers to external charging equipment for plug-in hybrid electric vehicles and battery electric vehicles, including all power supply devices connected to AC voltage and equipped with a charging plug.

　　2. AC charging

　　This often refers to a method of charging the traction battery pack by rectifying alternating current into direct current using an on-board charger.

　　3. DC charging

　　Refers to a method of charging a power battery using direct current.

　　4. Charging Cut-off Device (CCID)

　　Refers to the leakage protection device in the charging circuit; when a leakage current is detected in the vehicle, the CCID interrupts the current flow between the charging cable and the vehicle.

　　5. Charger

　　A device that converts alternating current (AC) output from electrical equipment or other power supply devices into direct current (DC) for charging. On-board chargers are installed in vehicles, while off-board chargers are part of the EVSE.

　　6. Charge connector

　　Also known as a charging gun, it is a device that plugs into the vehicle’s charging port to charge the traction battery.

　　7. Charging port/Charge inlet

　　Refers to the electrical socket installed on electric vehicles and plug-in hybrid vehicles, typically located behind a protective cover. The technical standard of the charging port or inlet must match the charging plug inserted into the vehicle in order for charging to occur.

　　8. Charging cable

　　A portable charging device with one end plugged into the vehicle and the other into a 220V wall outlet.

　　9. Charging station

　　A stationary device that delivers electrical energy to plug-in hybrid or battery electric vehicles, typically installed in home garages, workplaces, parking lots, or public areas. Depending on the charging duration, they are classified as DC charging stations or AC charging stations.

　　Secondly, we need to clarify what components make up the charging system for new energy vehicles.

　　The function of the charging system for new energy vehicles

　　The charging system for new energy vehicles can promptly supply power to the traction battery, ensuring its normal operation, and can dynamically adjust the charging current based on the battery’s state of charge and ambient conditions during charging.

　　Components of the charging system

　　New energy vehicle charging systems comprise numerous components, including on-board chargers, on-board charging connectors, DC/DC converters, and associated wiring harnesses.

　　1. On-board charger

　　The primary function of an on-board charger is to convert 220V AC mains power into high-voltage DC to charge the traction battery, replenishing its state of charge. (Based on data provided by the Battery Management System (BMS), the charger can dynamically adjust charging current or voltage parameters, execute corresponding control actions, and complete the charging process.)

　　The on-board charger can be divided internally into three parts: the main circuit (power circuit), the control circuit, and the wiring harness and standard components.

　　1) The main circuit is divided into two parts: the front end converts AC to constant DC, primarily using a full-bridge circuit plus a PFC circuit (PFC can be regarded as an AC/DC converter). The rear end is a DC/DC converter that transforms the high-voltage DC output from the front end into appropriate voltage and current levels to supply the traction battery.

　　2) The control circuit, whose core is the controller, manages the switching of MOSFETs, communicates with the BMS, monitors the charger’s status, and performs functions such as handshaking with the charging station.

　　The charger control board primarily performs functions such as controlling, monitoring, metering, calculating, correcting, and protecting the main circuit, as well as communicating with external networks; it serves as the “central brain” of the on-board charger.

　　Once the on-board charger is connected to AC power, it does not immediately deliver electrical energy to the battery. Instead, the Battery Management System (BMS) first collects, analyzes, and assesses the battery’s state of charge, then adjusts the charger’s charging parameters accordingly.

　　3) The function of wire harnesses and standard components is to connect the main circuit and control circuit, and to secure components and circuit boards.

　　2. Vehicle charging port

　　The charging interface refers to the component used to connect a mobile cable to a new energy vehicle. It consists of a charging socket and a charging plug, and is an essential part of conductive charging systems. During charging, the charging plug mechanically couples with the charging socket to enable power transfer.

　　GB/T 20234.2-2015 “Coupling Devices for Conductive Charging of Electric Vehicles – Part 2: AC Charging Interface”

　　Rated values of the AC charging interface:

　　The vehicle interface and the power supply interface for charging mode 3 each comprise seven pairs of contacts, with the following electrical parameters and functional definitions:

　　Control and guidance circuit: a circuit designed for signal transmission or communication between electric vehicles and electric vehicle supply equipment.

　　Control Pilot (CP) Function: A function used to monitor the interaction between an electric vehicle and the electric vehicle supply equipment.

　　Connection Confirmation Function CC: A function that, via electronic or mechanical means, indicates the status of the vehicle plug being connected to the vehicle and/or the supply plug being connected to the charging equipment.

　　Contact arrangement:

　　Charging connection interface:

　　During the charging connection process, the protective earth contact is engaged first, and the control pilot and charging confirmation contacts are engaged last. During disconnection, the control pilot and charging confirmation contacts are disconnected first, and the protective earth contact is disconnected last.

　　The control guidance circuit performs connection verification of the charging connector and determines the rated current parameters. This circuit comprises a power supply control unit, contactors K1 and K2, resistors R1, R2, R3, R4, RC, diodes D1, switches S1, S2, S3, an on-board charger, and a vehicle control unit; the vehicle control unit may be integrated into the on-board charger or another onboard control module. Resistors R4 and RC are mounted on the vehicle plug. Switch S1 is an internal switch within the power supply equipment. Switch S2 is an internal vehicle switch that closes when the vehicle interface is fully connected to the power supply interface and the electronically locked interface is fully engaged, provided the on-board charger has completed self‑diagnostics with no faults and the battery pack is in a chargeable state (if the vehicle features a “charge request” or “charge control” function, the vehicle must also be in the “charge request” or “chargeable” state). Switch S3 is an internal normally closed switch in the vehicle plug, interlocked with the push‑down button on the plug (used to trigger the mechanical locking mechanism); pressing the button releases the mechanical lock while simultaneously opening S3. The control guidance circuit may omit switch S2; vehicles without S2 shall use single‑phase charging with a maximum charging current not exceeding 8 A.