Three major standards for charging piles: national standards, energy bureau standards and national grid standards

"Without rules, there is no order." With the rapid popularization of electric vehicles, the number of charging piles is also increasing rapidly. In order to ensure the safety and consistency of charging, the state and the Energy Bureau and other units and departments have issued a series of standard regulations and are constantly updating them.

At present, the standards for new energy vehicle charging piles can be roughly divided into three levels: national standards, energy bureau standards, and state grid standards. The following are detailed classifications and standards:

1. National Standard: my country formulated a series of basic standards for electric vehicle charging piles in 2011, including general rules for charging piles, technical requirements for AC and DC charging, and communication guidelines between charging equipment and battery management system (BMS). In particular, based on the initial version of the standard in 2006, the 2011 standard further improved the interface design and DC charging protocol, making it compatible with most new energy vehicles and charging piles on the market. In addition, in order to solve the compatibility and safety issues between vehicles and charging piles, the 2015 standard revised and expanded the 2011 standard.

2. Energy Bureau standards: also known as industry standards, mainly focus on the testing rules and requirements of charging piles in terms of charging efficiency, communication means, safety protection and electromagnetic compatibility. All charging piles that wish to be put into operation on the market must comply with this authoritative standard of the Energy Bureau.

3. National Grid Standard: This standard is more specific and strict, especially for the CAN communication compatibility test of DC charging piles. It adds physical layer and link layer test items to ensure that charging piles under the State Grid have stronger stability and anti-interference ability in communication. This standard is the key technical criterion for the State Grid when purchasing and accepting charging piles.

At present, the relevant standards for charging piles are mainly divided into three types: national standards, national grid standards and energy bureau standards.

National Standards

The 2011 national standard is mainly divided into three aspects: general requirements, AC and DC, and charger and BMS communication, as follows:

GBT 18487.1-2011 Electric vehicle conductive charging system Part 1: General requirements;

GBT 20234.1-2011 Connection devices for conductive charging of electric vehicles Part 1: General requirements;

GBT 27930-2011 Communication protocol between off-board conductive charger and battery management system of electric vehicles.

The 2011 standard is based on the 2006 charging pile standard GBT 20234-2006. It improves the interface description and unifies the DC charging protocol. It is the current standard for charging piles and electric vehicles in operation.

The 2015 national standard is the same as the 2011 standard, and also stipulates from the following three aspects: general requirements, AC and DC, and charger and BMS communication. However, the 2015 standard corrects and supplements the deficiencies of the 2011 standard, mainly to solve the compatibility problem between the car and the charging pile, and to solve the safety problem in use. It ensures that the charging process is "unique" so that each charging pile and electric vehicle can charge safely and reliably.

At the same time, in order to ensure the consistency of interconnection and avoid different understandings among testing institutions, the following two national standards will be released:

GB Electric Vehicle Conductive Charging Interoperability Test Specification (has been submitted to the Standardization Committee);

GB Communication protocol consistency test between off-board conductive charger and battery management system of electric vehicles (has been submitted to the Standardization Committee).

Energy Bureau Standards

The Energy Bureau standards, also known as industry standards, mainly include the following two:

"NBT 33008.1-2013 Electric Vehicle Charging Equipment Inspection and Test Specification Part 1: Off-board Charger";

"NBT 33008.2-2013 Electric Vehicle Charging Equipment Inspection and Test Specification Part 2: AC Charging Pile".

It mainly stipulates the testing methods and requirements for the charging function, communication method, safety protection, electromagnetic compatibility, etc. of AC/DC charging piles. It is an authoritative standard that all charging piles currently put into operation on the market must pass.

3. National Grid Standards

The State Grid standards, also known as enterprise standards, mainly include the following two:

"QGDW 1591-2014 Technical Specifications for Inspection of Non-on-board Chargers for Electric Vehicles";

"QGDW 1592-2014 Technical Specifications for Inspection of Electric Vehicle AC Charging Piles".

The content of the standard is similar to the industry standard, but the testing requirements are more stringent, especially in terms of the compatibility of DC charging pile CAN communication, which adds physical layer and link layer test items to ensure the robustness of the CAN communication of the State Grid charging piles. It is the acceptance standard for the State Grid charging pile bidding.

To charge an electric vehicle, the AC power from the power grid needs to be converted into DC power, and the voltage range of the DC power should be consistent with the voltage range of the battery. The current can be large or small. A large current will charge faster, and a small current will charge slower. To convert AC power into DC power, a switching power supply based on power electronics technology is required. This switching power supply is made of high power and has a large charging current. It is installed outside the vehicle, which is a charging device called a "DC charging pile". This charging device is connected to the "fast charging port" on the electric vehicle; it can also be made into a low-power on-board charger (OBC) and arranged inside the vehicle. The power grid sends the AC power from the power grid to the "slow charging port" on the vehicle through an external charging device called an "AC charging pile". The vehicle sends the AC power from the "slow charging port" to the input end of the OBC. The AC charging pile only plays a role in monitoring and billing, and does not perform power conversion. There are four main power sizes of OBC: 3.3kW and 6.6kW based on single-phase 220V input, 11kW and 22kW based on three-phase 380V input, of which 6.6kW is the most mainstream.

The current mainstream electric vehicle charging system is constructed according to the above ideas, as shown in Figure 1.

Most electric vehicles have two charging ports: AC charging port, commonly known as slow charging; DC charging port, commonly known as fast charging. There is only one total positive interface and total negative interface on the battery. Both the fast charging port and the slow charging port need to be transferred to the copper bus (battery bus) through the high-voltage distribution box (PDU, Power Distribution Unit), and then connected to the total positive and total negative connectors of the battery. The battery needs to be connected to multiple components such as electronic control, DC/DC, OBC, fast charging, air conditioning, heater, etc. at the same time, and PDU seems indispensable.