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Hybrid-EV Committee Publishes SAE J3072 on Interconnection Requirements for Onboard, Grid Support Inverter Systems

Guest Post By Hank McGlynn
Posted: June 19, 2024

Questions about grid support for vehicles abound across the U.S.

The California Public Utility Commission (CPUC) directed its utilities to work with industry and standards development organizations (SDO) to develop standards to support AC Vehicle to Grid (V2G-AC).

SAE J3072 was identified by the CPUC as a standard to be considered for the vehicle.

As part of this utility-led activity, UL is working on an EV Supply Equipment (EVSE) standard, “UL 1741 Supplement SC” that aligns with an EV certified to SAE J3072. This UL standard is expected to be published in 2024. The SunSpec Alliance published the “IEEE 2030.5 V2G-AC Profile Implementation Guide for SAE J3072” in June 2022.  This 2024 revision of SAE J3072 corrects errors and omissions identified during the development of these documents as well as including other enhancements.

SAE J3072 establishes requirements for a grid support inverter system function which is integrated into a Plug-in Electric Vehicle (PEV) which connects in parallel with an electric power system (EPS) by way of conductively coupled, EVSE. This standard also defines the communication between the PEV and the EVSE required for the PEV onboard inverter function to be configured and authorized by the EVSE for discharging at a site.

J3072 is required to be used in conjunction with IEEE 1547-2018 and IEEE 1547.1-2020 or later versions.  Optional certification to IEEE 1547-2003 and IEEE 1547.1-2005 have been deleted and a four-quadrant converter is now mandatory.  This elimination resulted in many of the changes to section 4.6 between this version and the previous March 2021 version of the Standard. 

Utility grid codes in the United States and Canada are generally based on IEEE 1547 and this limits J3072 to these regions.  The IEEE 1547 documents are not generally used in other regions of the world and grid codes may be more local which is a challenge for a roaming V2G-AC inverter.   SAE could consider future regional versions for J3072, but there are no compelling regional grid code standards at this time. For V2G-DC the EVSE inverter is fixed to a specific location and the roaming V2G-DC vehicle is not impacted by local grid codes.

The original J3072 introduced the concept of “System Type” which designated a communication protocol stack for all layers and a specific physical charging connector.  System Type A1 was defined as a J1772 connector and protocol stack starting with a PLC physical layer to IEEE 2030.5 application layer.  System Type B1 used a J3068 connector and a protocol stack ending with a SunSpec Modbus application layer.  The letter and number were just an arbitrary pairing. 

This version defines a new system type concept while retaining types A1 and B1 for legacy equipment.   A “System Type” shall be assigned to the PEV onboard inverter system based on the charging receptacle installed on the PEV and the complete communication protocol stack from the physical layer through the application layer.  These are shown in the table below:

The new system type uses a letter to designate a protocol stack and a number to designate a connector.  So, system type “C1” pairs the IEEE 2030.5 stack with the J1772 connector and is equivalent to the legacy type A1.  And type C3 uses IEEE 2030.5 with the J3400 connector.

Because of interest in using ISO 15118, a type E[*] is being introduced for technical demonstrations.  It is not yet capable of meeting the requirements of J3072 4.6 and there are conformance issues with IEEE 1547-2018 10.7, but these issues are being worked. 

Hank McGlynn continued to lead the J3072 effort and this version, J3072-2024, is a major step on the way to achieving V2G-AC since it also aligns with the release of the SunSpec Alliance Implementation Guide, along with IEEE and UL updates.

Want to learn more? Buy SAE J3072 today.