Electric Vehicle Charging Inlet (EVI): Components and Interfaces

Electric Vehicle Charging Inlet (EVI): Components and Interfaces

Read an interesting article of History of EV Charging to gain more details on evolution of EV charging.

The EV charging inlet is the port on the vehicle that connects to the charging cable (charging gun). It serves as the physical and electrical interface through which the vehicle receives power from an external source. Beyond simply transferring electricity, the inlet also facilitates communication between the vehicle and the charging station, ensuring that the charging process is safe, efficient, and compatible with various charging systems.

Electric vehicle inlets come in various standard types, each featuring unique interfaces and components. Before diving into the details of which components are present in each type of inlet, let us first explore the general interfaces and components across these systems. This foundational understanding will provide clarity when examining the variations between different inlets. Below is a general and simple representation of the interfaces found in an Electric Vehicle Charging Inlet (EVI).

General representation of Components and Interfaces in EVI
Typical Combined Charging Standard-2 (CCS2) Inlet

Let’s look into the differences interfaces and components of EVI:

Power Lines:

Power lines are the primary pathways for transferring electricity to the vehicle’s battery or OBC, and they include the following types:

  • AC Lines:
    • Carry alternating current (AC) to OBC.
    • Can support single-phase or three-phase charging.
    • Example:
      • In the USA, single-phase AC charging is standard.
      • In Europe and many other regions, three-phase AC charging is common.
  • DC Lines:
    • Deliver direct current (DC) for fast charging, bypassing the vehicle’s onboard AC-DC converter.

Signal Lines:

Signal lines serve multiple critical purposes:

  • Detect the connection of the charge cord (or charging gun) to the vehicle.
  • Facilitate the exchange of hardwired signals between the Electric Vehicle Communication Controller (EVCC) and the charging station to manage the charging process

Communication Lines:

  • These lines enable advanced data exchange between the EVCC and the charging station.

Protective Earth:

  • Provides a reference for all signal measurements to ensure consistent and accurate measurement.
  • Provides a reference for communication signals.
  • Serves as the return path for ground fault currents, enhancing the safety of the charging system.

Auxiliary Power Lines:

  • These low-voltage lines supply power from the charging station to the vehicle.
  • Use Case: Serve as a backup power source if the vehicle’s low-voltage battery is depleted.
  • Modern Trend: Rarely used in newer EVs as onboard battery systems have improved.

Temperature Sensing:

  • Purpose: To monitor the temperature at key connection points, preventing overheating and potential damage to EVI.
  • Temperature sensors are present on both DC lines.
  • One or more temperature sensors may be placed on the AC lines.
  • Typically, NTC (Negative Therma Coefficient) thermistors are used due to their high sensitivity to temperature changes, compact size, and reliability over a wide operating temperature range.
Mesaurement setup for temperature sensing (shown only for one sensor)
Position of the temperature sensors in EVI

Unlock Button:

  • Located near the charging inlet for convenience.
  • Typically a push button is used.
  • Function:
    • Allows users to stop charging and release the charging cord manually.
    • Monitoring the status of this button is essential for system reliability.
Unlock button status (Pressed / not pressed) detection
Unlock button on EVI

Charging Status LED:

  • Purpose: To visually indicate the progress and status of the charging process.
  • Features:
    • The number of interfaces between the LED and the EVCC depends on the chosen design. A simple LED setup requires fewer interfaces, whereas a more advanced or complex LED system demands additional interfaces to support its functionality.
    • Typical indications include (Example):
      • Blinking Green: Charging in progress.
      • Green: Charging completed.
      • Red: Error or fault detected.
    • The status LED consists of a group of Red, Green, and Blue LEDs. 
    • By adjusting the PWM signals to the Red, Green, and Blue LEDs, various colors can be generated.
Charging status LED control (with only one LED)
Simple chargig status LED
Complex charging status LED

Locking Motor:

  • Ensures the charging gun is securely locked into the EVI during charging.
  • Mechanism: EVCC drives the locking motor pin to locked position to secure the connection, preventing accidental disconnection.
  • Emergency Feature: Includes a manual release wire to unlock the connector in case of motor failure, ensuring the vehicle remains operational.
  • Interfaces for Locking motor position status is provided to EVCC.
  • Some types of EVIs do not include a locking motor. In such cases, the locking mechanism is integrated into the charging gun instead.
  • The following is an example of locking motor control and status sensing. When S1 and S4 are closed, the motor locks, and when S2 and S3 are closed, it unlocks. The position of the locking pin is detected by sensing the variation in resistance, which changes based on the pin’s position.
Locking motor control and position sensing
Locking motor in EVI

Protective Cover:

  • A protective cover in an EV inlet shields the charging port from dust, moisture, and debris when not in use, ensuring reliable operation and extending the lifespan of the connectors.
Example Protective Covers

Interfaces and Components of Standard Inlet Types:

Let’s explore the interfaces and components in standard inlet types. Since the Unlock Button and Charging Status LED are common to all inlets, we will focus on the remaining elements.

1. J1772 (IEC 62196 Type 1) Inlet:

J1772 (IEC 62196 Type 1) Inlet
  • It is only for AC single phase charging.
  • Used mainly in Plugin Hybrids where DC charging is not necessary.
  • Used in North Americal region and few other parts of the world.
  • AC Power Lines:
    • L1: Phase-1
    • N: Neutral
  • Signal Lines:
    • PP: Proximity Pilot (to detect the Chargin cable (charge gun) connection status.
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There may be one sensor on Phase or Neutral
  • Locking Motor:
    • The locking motor is integrated into the EVI.
    • When the charging gun is connected to the EVI, the mechanical latch locks the charging gun in place.
    • Subsequently, the locking motor pin engages with the mechanical latch, preventing the release of the charging gun even when the Release Button is pressed. This mechanism ensures that accidental disconnection of the charging gun is not possible.
    • Locking motor status (locked or unlocked) is sensed by EVCC.

2. IEC 62196 Type 2 Inlet:

IEC 62196 Type 2 Inlet
  • It is only for AC charging.
  • Used mainly in Plugin Hybrids where DC charging is not necessary.
  • Used in Europe region and few other parts of the world.
  • AC Power Lines:
    • L1: Phase-1
    • L2: Phase-2
    • L3: Phase-3
    • N: Neutral
  • Signal Lines:
    • PP: Proximity Pilot (to detect the Chargin cable (charge gun) connection status.
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There may be one or more sensors on AC power lines
  • Locking Motor:
    • The locking motor is integrated into the EVI.
    • The locking motor pin engages into the slot on the charge gun, to ensures that accidental disconnection of the charging gun is not possible.
    • Locking motor status (locked or unlocked) is sensed by EVCC.

3. Combined Charging Standard-1 (CCS1) Inlet:

Combined Charging Standard-1 (CCS1) Inlet
  • It is a combined inlet for both AC and DC charging.
  • Used in North Americal region and few other parts of the world.
  • AC Power Lines:
    • L1: Phase-1
    • N: Neutral
  • DC Power Lines:
    • DC+
    • DC-
  • Signal Lines:
    • PP: Proximity Pilot (to detect the Chargin cable (charge gun) connection status.
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There will be one temperature sensor on each DC power line, for a total of two sensors.
    • There may be one sensor on Phase or Neutral
  • Locking Motor:
    • Same as J1772 Type-1 inlet.

4. Combined Charging Standard-2 (CCS2) Inlet:

Combined Charging Standard-2 (CCS2) Inlet
  • It is a combined inlet for both AC and DC charging.
  • Used in Europe region and few other parts of the world.
  • AC Power Lines:
    • L1: Phase-1
    • L2: Phase-2
    • L3: Phase-3
    • N: Neutral
  • DC Power Lines:
    • DC+
    • DC-
  • Signal Lines:
    • PP: Proximity Pilot (to detect the Chargin cable (charge gun) connection status.
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There will be one temperature sensor on each DC power line, for a total of two sensors.
    • There may be one or more sensors on AC power lines
  • Locking Motor:
    • Same as IEC 62196 Type-2 inlet

5. GB/T AC (GB/T 20234.2) Inlet:

GB/T AC (GB/T 20234.2) Inlet
  • It is only for AC charging.
  • Used in China region and few other parts of the world.
  • AC Power Lines:
    • L1: Phase-1
    • L2: Phase-2
    • L3: Phase-3
    • N: Neutral
  • Signal Lines:
    • PP: Proximity Pilot (to detect the Chargin cable (charge gun) connection status.
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There may be one or more sensors on AC power lines
  • Locking Motor:
    • Same as IEC 62196 Type-2 inlet

6. GB/T DC (GB/T 20234.3) Inlet:

GB/T DC (GB/T 20234.3) Inlet
  • It is only for DC charging.
  • Used in China region and few other parts of the world.
  • DC Power Lines:
    • DC+
    • DC-
  • Signal Lines:
    • CC1: Connection confirmtion-1
    • CC2: Connection confirmtion-2
  • Communicatin Lines:
    • S+: CAN-H
    • S-: CAN-L
  • Auxiliary Power:
    • A+, A-: Auxiliary DC power
  • PE: Protective Earth
  • Temperature Sensing:
    • There will be one temperature sensor on each DC power line, for a total of two sensors.
  • Locking Motor:
    • Locking motor is positioned inside the charge gun. Once the charge gun is connected to EVI, it will not allow to press the Release Button.
    • EVCC does not sense the locking motor status.

In China region, Inlet with both AC and DC charging looks as below:

Inlet with GBT-DC and GBT-AC integrated

7. CHAdeMO Inlet:

CHAdeMO Inlet
Pins in the CHAdeMO Inlet
  • It is only for DC charging.
  • Used in Japan region and few other parts of the world.
  • DC Power Lines:
    • DC+
    • DC-
  • Signal Lines:
    • SS1 / SS2: Charge sequence signal
    • DCP: Charging enable
    • PP: Proximity Pilot
  • Communicatin Lines:
    • C-H: CAN-H
    • C-L: CAN-L
  • Auxiliary Power:
    • A+, A-: Auxiliary DC power
  • FG: Protective Earth
  • N/C: Not connected (Not used)
  • Temperature Sensing:
    • There will be one temperature sensor on each DC power line, for a total of two sensors.
  • Locking Motor:
    • Locking motor is positioned inside the charge gun. Once the charge gun is connected to EVI, it will not allow to press the Release Button.
    • EVCC does not sense the locking motor status.

In Japan region, CHAdeMO is used for DC charging and J1772 Type-1 is used for AC charging. the integrated Inlet looks as below:

Integrated CHAdeMO and Type-1 Inlet

8. North Americal Charging Standard (NACS) or Tesla Inlet:

North Americal Charging Standard (NACS) or Tesla Inlet
  • It is a combined inlet for both AC and DC charging.
  • It uses same lines for AC and DC charging which is unique compared to all other inlets.
  • Used in North Americal region.
  • Power Lines:
    • DC+/L1 : DC+ and Phase-1
    • DC-/L2 : : DC- and Neutral
  • Signal Lines:
    • PP: Proximity Pilot
  • Communicatin Lines:
    • CP: Control Pilot
  • PE: Protective Earth
  • Temperature Sensing:
    • There will be one temperature sensor on each power line, for a total of two sensors.
  • Locking Motor:
    • Same as IEC 62196 Type-2 inlet.

Below picture shows, how AC and DC power lines are used in NACS.

Simple representation of charging architecture with NACS

In addition to the standard inlets mentioned above, two more inlets are currently under development: the Megawatt Charging System (MCS) and ChaoJi.

The EVI is a crucial component enabling safe and efficient energy transfer between an EV and a charging station. Its design seamlessly integrates power lines for energy transfer, signal interfaces for communication and control, and safety mechanisms such as locking systems and temperature sensors to ensure reliable and secure operation under various conditions. The EVI’s robust design is engineered to handle diverse power levels and charging environments, making it an importanct component of modern electric mobility.

Amar Reddy Avatar
Amar Reddy, a seasoned professional in EV Charging with more than a decade of expertise in the Electric Vehicles domain. With a Master’s degree in Electrical Engineering, he is eager to share valuable insights into EV charging, catering to enthusiasts and fostering a deeper understanding of the field.

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