1. EV Charging Connector Standards

International organizations have been working for many years to enact their connection standards regarding the high-power charging of EVs. The commonly used technologies are (a) AC on-board charging and (b) DC off-board charging. In previous years, European EV manufacturers have rather produced EVs with on-board chargers which are compatible with a high-power AC supply. However, since the company TEPCO introduced a standard Japanese socket for DC connection, namely CHAdeMO, DC off-board charging is becoming more common. CHAdeMO is now available in several European countries, and although it is not internationally standardized yet, it is widely used in the US and Japan^[1]. The SAE also has been developing its own connector standard called Combo. In SAE J1772, the Combo coupler features extra pins compared to the standard version^[2].

1.1. AC Charging Connector

The IEC 62196-2 standard defines three types of connectors for AC supply power in Europe. These types of connectors are described in Table 1.

Table 1. IEC 62196-2 Connector Standard for AC charging^[3].

The IEC 62196-2 Type 1 is not different compared to the SAE J1772 which is widely used in the US and Japan. In China, the IEC 62196-2 Type 1 is also known as GB/T 20234.2-2015 connector. Notice that China has modified it by changing it from an electronic lock into a mechanic lock (with the option of an electronic lock) and the control pilot is using two short pins.

1.2. DC Charging Connector

The most common use of fast charging technologies is to supply direct current to the EV battery. This requires an off-board charging station to supply high levels of current and to transform the AC of the distribution grid to DC for the charging of the EV’s battery. CHAdeMO was the first fast-charging method in the world, specified by the Japan Electric Vehicle Standard (JEVS) G105-1993 from the JARI (Japan Automobile Research Institute), and it has been developed by the Japanese company TEPCO. CHAdeMO is an abbreviation of “CHArge de MOve” or “move by charge”^[4]. The connector includes two large pins for DC power, plus other pins to carry CAN-BUS connections. The CHAdeMO transmits the information by CAN-BUS and analog control lines. This hybrid communication protocol has more advantages compared to pure digital control since it can let the system double-check the digital control system. Once the analog signal is lost, an immediate charging operation shutdown can be performed [28]. The CHAdeMO specifications comply with the international standard IEC 62196-3. The characteristics of CHAdeMO are shown in Table 2.

Table 2. CHAdeMO connector characteristics^[5].

The configuration of CHAdeMO only specifies the necessary and effective parts for connection. A summary and pinout of CHAdeMO are shown in Table 3.

Table 3. CHAdeMO pinout functionalities^[6].

1.3. Combined Charger Connector (J1772-2009 Combo)

In parallel to CHAdeMO, the US and some European EV manufacturers such as Audi, BMW, Daimler, Ford, General Motors, Porsche, or Volkswagen have been developing a new system for fast charging: the Combined Charging System (CCS), i.e., J1772-2009 Combo. The main goal of this standard is to allow the EV to charge in both AC (slow/medium charging) and DC (fast charging), which is different from CHAdeMO as it only allows DC and needs an extra socket for AC charging.

There are two types of Combo CCS currently available. The Combo Type 1 connector for the US has been developed based on the AC Type 1 connector (specified by the standards SAE J1772/UNE EN 62196-2). The Combo Type 2 for Europe integrates a Type 2 connector as defined in the standard UNE EN 62196-2^[7]. The main characteristics of Combo connectors Type 1 and Type 2 are summarized in Table 4.

Table 4. Main characteristics of Combo connectors Type 1 and type 2^[5].

The Combo Type 1 and Type 2 have different pinout configurations based on their different functionalities. Table 5 shows the configuration and the functions of the pins in Combo Type 1 and Type 2.

Table 5. The pin configuration and functionality of Combo connectors Type 1 and Type 2^[6].

Currently, GB/T was giving just 237.5 kW at 950 V and 250 A; thus, this will be about four times more competent in terms of power than other DC charging connectors. Power will be more than twice as high as the new 400 kW CHAdeMO and 350 kW CCS Combo specs, too. However, the V2G features are not supported by GB/T connector standard. The feature comparison among the DC charging connector standards is listed Table 6 below:

Table 6. Specification comparison of different DC charging connector standards^[7].