Communication Between Plug-In Vehicles and Off-Board DC Chargers
This SAE Recommended Practice SAE J2847-2 establishes requirements and specifications for communication between Plug-in Electric Vehicle (PEV) and the DC Off-board charger. Where relevant, this document notes, but does not formally specify, interactions between the vehicle and vehicle operator.
This document applies to the off-board DC charger for conductive charging, which supplies DC current to the Rechargable Energy Storage System (RESS) of the electric vehicle through a SAE J1772™ coupler. Communications will be on the SAE J1772 Pilot line for PLC communication. The details of PowerLine Communications (PLC) are found in SAE J2931/4.
The specification supports DC energy transfer via Forward Power Flow (FPF) from source to vehicle.
SAE has published multiple documents relating to PEV and vehicle-to-grid interfaces. The various document series are listed below, with a brief explanation of each.
Figure 1.1 shows the sequencing of these documents and their primary function (e.g., the J2836 and J2847/1 documents start with Smart Charging, J2836 and J2847/2 then adds DC charging, etc.). The intent is to have subsequent slash sheets complement each other as more functions and features are included. The /6 series of documents add wireless charging items not already included in the proceeding slash sheets. These are all then included in Interoperability in SAE J2953 and security in SAE J2931/7. J3072 then includes the PEV to grid requirements for Vehicle to Grid (V2G) power and communication to match J2836/3 Use Cases.
The summary of documents for DC Charging is then as follows:
SAE J1772™ is the PEV to EVSE systems document and includes the system and timing diagrams for DC Charging
SAE J2836/2™ starts with the Use Cases for DC Charging communications
SAE J2847/2 then transforms these Use Case requirements into the signals and messages
SAE J2931/1 is where the Protocol requirements are placed for all PEV communications
SAE J2931/4 is used for the PLC communication requirements for DC Charging since it is only a wired median
SAE J2953/1 is the Interoperability requirements
SAE J2953/2 is the Interoperability procedure and plan
SAE J2847/2 provides messages for DC energy transfer. The updated version in August, 2012 was aligned with the DIN SPEC 70121 Candidate 2 and additions to J1772™ for DC charging, published October, 2012. This revision will include results from implementation and changes not included in the previous version. This will also include effects from DC discharging or Reverse Power Flow to off-board equipment that expands on J2847/3 for AC energy flow off the vehicle, and other Distributed Energy Resource functions that is being developed from the use cases in J2836/3™, published January, 2013.
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